A Framework for Enterprise Java

A Framework for Enterprise Java
Seam - Contextual Components
A Framework for
Enterprise Java
2.0.2.GA
by Gavin King (Project Lead), Pete Muir, Norman Richards, Shane
Bryzak, Michael Yuan, Mike Youngstrom, Christian Bauer, Jay
Balunas, Dan Allen, Max Rydahl Andersen, and Emmanuel Bernard
edited by Samson Kittoli
and thanks to James Cobb (Graphic Design), Cheyenne
Weaver (Graphic Design), Mark Newton, and Steve Ebersole
Introduction to JBoss Seam .............................................................................................. xv
1. Contribute to Seam ............................................................................................. xix
1. Seam Tutorial .............................................................................................................. 1
1.1. Try the examples ................................................................................................ 1
1.1.1. Running the examples on JBoss AS ......................................................... 1
1.1.2. Running the examples on Tomcat ............................................................. 1
1.1.3. Running the example tests ....................................................................... 2
1.2. Your first Seam application: the registration example ............................................ 2
1.2.1. Understanding the code ........................................................................... 2
1.2.2. How it works .......................................................................................... 14
1.3. Clickable lists in Seam: the messages example .................................................. 15
1.3.1. Understanding the code .......................................................................... 15
1.3.2. How it works .......................................................................................... 21
1.4. Seam and jBPM: the todo list example ............................................................... 21
1.4.1. Understanding the code .......................................................................... 22
1.4.2. How it works .......................................................................................... 29
1.5. Seam pageflow: the numberguess example ........................................................ 29
1.5.1. Understanding the code ..........................................................................
1.5.2. How it works ..........................................................................................
1.6. A complete Seam application: the Hotel Booking example ...................................
1.6.1. Introduction ............................................................................................
1.6.2. Overview of the booking example ............................................................
1.6.3. Understanding Seam conversations .........................................................
1.6.4. The Seam UI control library ....................................................................
1.6.5. The Seam Debug Page ..........................................................................
1.7. A complete application featuring Seam and jBPM: the DVD Store example ...........
1.8. An example of Seam with Hibernate: the Hibernate Booking example ...................
1.9. A RESTful Seam application: the Blog example ..................................................
1.9.1. Using "pull"-style MVC ............................................................................
1.9.2. Bookmarkable search results page ..........................................................
1.9.3. Using "push"-style MVC in a RESTful application .....................................
2. Getting started with Seam, using seam-gen ..............................................................
2.1. Before you start ................................................................................................
2.2. Setting up a new Eclipse project ........................................................................
2.3. Creating a new action .......................................................................................
2.4. Creating a form with an action ...........................................................................
2.5. Generating an application from an existing database ...........................................
2.6. Generating an application from existing JPA/EJB3 entities ...................................
2.7. Deploying the application as an EAR .................................................................
2.8. Seam and incremental hot deployment ...............................................................
2.9. Using Seam with JBoss 4.0 ...............................................................................
2.9.1. Install JBoss 4.0 ....................................................................................
2.9.2. Install the JSF 1.2 RI .............................................................................
3. Getting started with Seam, using JBoss Tools ..........................................................
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3.1. Before you start ................................................................................................
3.2. Setting up a new Seam project ..........................................................................
3.3. Creating a new action .......................................................................................
3.4. Creating a form with an action ...........................................................................
3.5. Generating an application from an existing database ...........................................
3.6. Seam and incremental hot deployment with JBoss Tools .....................................
4. The contextual component model .............................................................................
4.1. Seam contexts ..................................................................................................
4.1.1. Stateless context ....................................................................................
4.1.2. Event context .........................................................................................
4.1.3. Page context ..........................................................................................
4.1.4. Conversation context ..............................................................................
4.1.5. Session context ......................................................................................
4.1.6. Business process context .......................................................................
4.1.7. Application context .................................................................................
4.1.8. Context variables ...................................................................................
4.1.9. Context search priority ............................................................................
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4.1.10. Concurrency model .............................................................................. 98
4.2. Seam components ............................................................................................ 99
4.2.1. Stateless session beans ......................................................................... 99
4.2.2. Stateful session beans ........................................................................... 99
4.2.3. Entity beans ......................................................................................... 100
4.2.4. JavaBeans ........................................................................................... 100
4.2.5. Message-driven beans .......................................................................... 101
4.2.6. Interception .......................................................................................... 101
4.2.7. Component names ............................................................................... 102
4.2.8. Defining the component scope .............................................................. 103
4.2.9. Components with multiple roles ............................................................. 103
4.2.10. Built-in components ............................................................................ 104
4.3. Bijection .......................................................................................................... 104
4.4. Lifecycle methods ........................................................................................... 107
4.5. Conditional installation ..................................................................................... 108
4.6. Logging .......................................................................................................... 109
4.7. The Mutable interface and @ReadOnly ............................................................. 110
4.8. Factory and manager components ................................................................... 113
5. Configuring Seam components ............................................................................... 117
5.1. Configuring components via property settings ................................................... 117
5.2. Configuring components via components.xml ................................................... 117
5.3. Fine-grained configuration files ........................................................................ 121
5.4. Configurable property types ............................................................................. 122
5.5. Using XML Namespaces ................................................................................. 123
6. Events, interceptors and exception handling ........................................................... 129
6.1. Seam events .................................................................................................. 129
6.2. Page actions ................................................................................................... 130
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6.3. Page parameters ............................................................................................
6.3.1. Mapping request parameters to the model .............................................
6.4. Propagating request parameters ......................................................................
6.5. Conversion and Validation ...............................................................................
6.6. Navigation ......................................................................................................
6.7. Fine-grained files for definition of navigation, page actions and parameters ..........
6.8. Component-driven events ................................................................................
6.9. Contextual events ...........................................................................................
6.10. Seam interceptors .........................................................................................
6.11. Managing exceptions .....................................................................................
6.11.1. Exceptions and transactions ................................................................
6.11.2. Enabling Seam exception handling ......................................................
6.11.3. Using annotations for exception handling .............................................
6.11.4. Using XML for exception handling .......................................................
6.11.5. Some common exceptions ..................................................................
7. Conversations and workspace management ...........................................................
7.1. Seam's conversation model .............................................................................
7.2.
7.3.
7.4.
7.5.
7.6.
7.7.
7.8.
7.9.
Nested conversations ......................................................................................
Starting conversations with GET requests .........................................................
Using <s:link> and <s:button> .....................................................................
Success messages .........................................................................................
Natural conversation ids ..................................................................................
Creating a natural conversation .......................................................................
Redirecting to a natural conversation ...............................................................
Workspace management .................................................................................
7.9.1. Workspace management and JSF navigation .........................................
7.9.2. Workspace management and jPDL pageflow ..........................................
7.9.3. The conversation switcher .....................................................................
7.9.4. The conversation list ............................................................................
7.9.5. Breadcrumbs ........................................................................................
7.10. Conversational components and JSF component bindings ...............................
7.11. Concurrent calls to conversational components ...............................................
7.11.1. RichFaces Ajax ..................................................................................
8. Pageflows and business processes .........................................................................
8.1. Pageflow in Seam ...........................................................................................
8.1.1. The two navigation models ...................................................................
8.1.2. Seam and the back button ....................................................................
8.2. Using jPDL pageflows .....................................................................................
8.2.1. Installing pageflows ..............................................................................
8.2.2. Starting pageflows ................................................................................
8.2.3. Page nodes and transitions ...................................................................
8.2.4. Controlling the flow ...............................................................................
8.2.5. Ending the flow ....................................................................................
8.2.6. Pageflow composition ...........................................................................
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8.3. Business process management in Seam ..........................................................
8.4. Using jPDL business process definitions ...........................................................
8.4.1. Installing process definitions ..................................................................
8.4.2. Initializing actor ids ...............................................................................
8.4.3. Initiating a business process .................................................................
8.4.4. Task assignment ..................................................................................
8.4.5. Task lists .............................................................................................
8.4.6. Performing a task .................................................................................
9. Seam and Object/Relational Mapping ......................................................................
9.1. Introduction .....................................................................................................
9.2. Seam managed transactions ............................................................................
9.2.1. Disabling Seam-managed transactions ..................................................
9.2.2. Configuring a Seam transaction manager ...............................................
9.2.3. Transaction synchronization ..................................................................
9.3. Seam-managed persistence contexts ...............................................................
9.3.1. Using a Seam-managed persistence context with JPA ............................
9.3.2. Using a Seam-managed Hibernate session ............................................
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9.3.3. Seam-managed persistence contexts and atomic conversations ..............
9.4. Using the JPA "delegate" ................................................................................
9.5. Using EL in EJB-QL/HQL ................................................................................
9.6. Using Hibernate filters .....................................................................................
JSF form validation in Seam ..................................................................................
Groovy integration .................................................................................................
11.1. Groovy introduction .......................................................................................
11.2. Writing Seam applications in Groovy ..............................................................
11.2.1. Writing Groovy components ................................................................
11.2.2. seam-gen ...........................................................................................
11.3. Deployment ...................................................................................................
11.3.1. Deploying Groovy code .......................................................................
11.3.2. Native .groovy file deployment at development time ..............................
11.3.3. seam-gen ...........................................................................................
The Seam Application Framework .........................................................................
12.1. Introduction ...................................................................................................
12.2. Home objects ................................................................................................
12.3. Query objects ................................................................................................
12.4. Controller objects ..........................................................................................
Seam and JBoss Rules ..........................................................................................
13.1. Installing rules ...............................................................................................
13.2. Using rules from a Seam component ..............................................................
13.3. Using rules from a jBPM process definition .....................................................
Security ..................................................................................................................
14.1. Overview ......................................................................................................
14.1.1. Which mode is right for my application? ...............................................
14.2. Requirements ................................................................................................
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14.3. Disabling Security .........................................................................................
14.4. Authentication ...............................................................................................
14.4.1. Configuration ......................................................................................
14.4.2. Writing an authentication method .........................................................
14.4.3. Writing a login form ............................................................................
14.4.4. Simplified Configuration - Summary .....................................................
14.4.5. Handling Security Exceptions ..............................................................
14.4.6. Login Redirection ................................................................................
14.4.7. HTTP Authentication ...........................................................................
14.4.8. Advanced Authentication Features .......................................................
14.5. Error Messages .............................................................................................
14.6. Authorization .................................................................................................
14.6.1. Core concepts ....................................................................................
14.6.2. Securing components .........................................................................
14.6.3. Security in the user interface ...............................................................
14.6.4. Securing pages ..................................................................................
14.6.5. Securing Entities ................................................................................
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14.7. Writing Security Rules ...................................................................................
14.7.1. Permissions Overview .........................................................................
14.7.2. Configuring a rules file ........................................................................
14.7.3. Creating a security rules file ................................................................
14.8. SSL Security .................................................................................................
14.9. CAPTCHA ....................................................................................................
14.9.1. Configuring the CAPTCHA Servlet .......................................................
14.9.2. Adding a CAPTCHA to a form .............................................................
14.9.3. Customising the CAPTCHA algorithm ..................................................
14.10. Security Events ...........................................................................................
14.11. Run As .......................................................................................................
14.12. Extending the Identity component .................................................................
15. Internationalization, localization and themes .........................................................
15.1. Internationalizing your app .............................................................................
15.1.1. Application server configuration ...........................................................
15.1.2. Translated application strings ..............................................................
15.1.3. Other encoding settings ......................................................................
15.2. Locales .........................................................................................................
15.3. Labels ..........................................................................................................
15.3.1. Defining labels ....................................................................................
15.3.2. Displaying labels ................................................................................
15.3.3. Faces messages ................................................................................
15.4. Timezones ....................................................................................................
15.5. Themes ........................................................................................................
15.6. Persisting locale and theme preferences via cookies .......................................
16. Seam Text ..............................................................................................................
16.1. Basic fomatting .............................................................................................
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16.2. Entering code and text with special characters ................................................
16.3. Links ............................................................................................................
16.4. Entering HTML ..............................................................................................
17. iText PDF generation .............................................................................................
17.1. Using PDF Support .......................................................................................
17.1.1. Creating a document ..........................................................................
17.1.2. Basic Text Elements ...........................................................................
17.1.3. Headers and Footers ..........................................................................
17.1.4. Chapters and Sections ........................................................................
17.1.5. Lists ...................................................................................................
17.1.6. Tables ................................................................................................
17.1.7. Document Constants ..........................................................................
17.1.8. Configuring iText ................................................................................
17.2. Charting ........................................................................................................
17.3. Bar codes .....................................................................................................
17.4. Rendering Swing/AWT components ................................................................
17.5. Further documentation ...................................................................................
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18. Email ......................................................................................................................
18.1. Creating a message ......................................................................................
18.1.1. Attachments .......................................................................................
18.1.2. HTML/Text alternative part ..................................................................
18.1.3. Multiple recipients ...............................................................................
18.1.4. Multiple messages ..............................................................................
18.1.5. Templating .........................................................................................
18.1.6. Internationalisation ..............................................................................
18.1.7. Other Headers ....................................................................................
18.2. Receiving emails ...........................................................................................
18.3. Configuration .................................................................................................
18.3.1. mailSession ......................................................................................
18.4. Meldware ......................................................................................................
18.5. Tags .............................................................................................................
19. Asynchronicity and messaging ..............................................................................
19.1. Asynchronicity ...............................................................................................
19.1.1. Asynchronous methods .......................................................................
19.1.2. Asynchronous methods with the Quartz Dispatcher ...............................
19.1.3. Asynchronous events ..........................................................................
19.2. Messaging in Seam .......................................................................................
19.2.1. Configuration ......................................................................................
19.2.2. Sending messages .............................................................................
19.2.3. Receiving messages using a message-driven bean ..............................
19.2.4. Receiving messages in the client .........................................................
20. Caching ..................................................................................................................
20.1. Using JBossCache in Seam ...........................................................................
20.2. Page fragment caching ..................................................................................
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21. Web Services .........................................................................................................
21.1. Configuration and Packaging .........................................................................
21.2. Conversational Web Services ........................................................................
21.2.1. A Recommended Strategy ..................................................................
21.3. An example web service ................................................................................
22. Remoting ................................................................................................................
22.1. Configuration .................................................................................................
22.2. The "Seam" object ........................................................................................
22.2.1. A Hello World example .......................................................................
22.2.2. Seam.Component ...............................................................................
22.2.3. Seam.Remoting ..................................................................................
22.3. Evaluating EL Expressions ............................................................................
22.4. Client Interfaces ............................................................................................
22.5. The Context ..................................................................................................
22.5.1. Setting and reading the Conversation ID ..............................................
22.5.2. Remote calls within the current conversation scope ..............................
22.6. Batch Requests .............................................................................................
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22.7. Working with Data types ................................................................................
22.7.1. Primitives / Basic Types ......................................................................
22.7.2. JavaBeans .........................................................................................
22.7.3. Dates and Times ................................................................................
22.7.4. Enums ...............................................................................................
22.7.5. Collections .........................................................................................
22.8. Debugging ....................................................................................................
22.9. The Loading Message ...................................................................................
22.9.1. Changing the message .......................................................................
22.9.2. Hiding the loading message ................................................................
22.9.3. A Custom Loading Indicator ................................................................
22.10. Controlling what data is returned ..................................................................
22.10.1. Constraining normal fields .................................................................
22.10.2. Constraining Maps and Collections ....................................................
22.10.3. Constraining objects of a specific type ...............................................
22.10.4. Combining Constraints ......................................................................
22.11. JMS Messaging ...........................................................................................
22.11.1. Configuration ....................................................................................
22.11.2. Subscribing to a JMS Topic ...............................................................
22.11.3. Unsubscribing from a Topic ...............................................................
22.11.4. Tuning the Polling Process ................................................................
23. Seam and the Google Web Toolkit ........................................................................
23.1. Configuration .................................................................................................
23.2. Preparing your component .............................................................................
23.3. Hooking up a GWT widget to the Seam component .........................................
23.4. GWT Ant Targets ..........................................................................................
24. Spring Framework integration ...............................................................................
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24.1. Injecting Seam components into Spring beans ................................................
24.2. Injecting Spring beans into Seam components ................................................
24.3. Making a Spring bean into a Seam component ...............................................
24.4. Seam-scoped Spring beans ...........................................................................
24.5. Using Spring PlatformTransactionManagement ...............................................
24.6. Using a Seam Managed Persistence Context in Spring ....................................
24.7. Using a Seam Managed Hibernate Session in Spring ......................................
24.8. Spring Application Context as a Seam Component ..........................................
24.9. Using a Spring TaskExecutor for @Asynchronous ...........................................
25. Hibernate Search ...................................................................................................
25.1. Introduction ...................................................................................................
25.2. Configuration .................................................................................................
25.3. Usage ...........................................................................................................
26. Configuring Seam and packaging Seam applications ............................................
26.1. Basic Seam configuration ..............................................................................
26.1.1. Integrating Seam with JSF and your servlet container ...........................
26.1.2. Using facelets ....................................................................................
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26.1.3. Seam Resource Servlet ...................................................................... 354
26.1.4. Seam servlet filters ............................................................................. 355
26.1.5. Integrating Seam with your EJB container ............................................ 359
26.1.6. Don't forget! ....................................................................................... 360
26.2. Using Alternate JPA Providers ....................................................................... 360
26.3. Configuring Seam in Java EE 5 ..................................................................... 361
26.3.1. Packaging .......................................................................................... 361
26.4. Configuring Seam in J2EE ............................................................................. 363
26.4.1. Boostrapping Hibernate in Seam ......................................................... 364
26.4.2. Boostrapping JPA in Seam ................................................................. 364
26.4.3. Packaging .......................................................................................... 364
26.5. Configuring Seam in Java SE, without JBoss Embedded ................................. 365
26.6. Configuring Seam in Java SE, with JBoss Embedded ...................................... 366
26.6.1. Installing Embedded JBoss ................................................................. 366
26.6.2. Packaging .......................................................................................... 367
26.7. Configuring jBPM in Seam ............................................................................. 368
26.7.1. Packaging .......................................................................................... 369
26.8. Configuring SFSB and Session Timeouts in JBoss AS ..................................... 370
26.9. Running Seam in a Portlet ............................................................................. 371
27. Seam annotations .................................................................................................. 373
27.1. Annotations for component definition .............................................................. 373
27.2. Annotations for bijection ................................................................................ 376
27.3. Annotations for component lifecycle methods .................................................. 380
27.4. Annotations for context demarcation ............................................................... 381
27.5. Annotations for use with Seam JavaBean components in a J2EE environment... 385
27.6. Annotations for exceptions ............................................................................. 386
27.7. Annotations for Seam Remoting ..................................................................... 386
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27.8. Annotations for Seam interceptors ..................................................................
27.9. Annotations for asynchronicity ........................................................................
27.10. Annotations for use with JSF .......................................................................
27.10.1. Annotations for use with dataTable ...................................................
27.11. Meta-annotations for databinding ..................................................................
27.12. Annotations for packaging ............................................................................
27.13. Annotations for integrating with the servlet container ......................................
28. Built-in Seam components .....................................................................................
28.1. Context injection components ........................................................................
28.2. Utility components .........................................................................................
28.3. Components for internationalization and themes ..............................................
28.4. Components for controlling conversations .......................................................
28.5. jBPM-related components ..............................................................................
28.6. Security-related components ..........................................................................
28.7. JMS-related components ...............................................................................
28.8. Mail-related components ................................................................................
28.9. Infrastructural components .............................................................................
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28.10. Miscellaneous components ..........................................................................
28.11. Special components ....................................................................................
Seam JSF controls .................................................................................................
29.1. Tags .............................................................................................................
29.1.1. Navigation Controls ............................................................................
29.1.2. Converters and Validators ...................................................................
29.1.3. Formatting ..........................................................................................
29.1.4. Seam Text .........................................................................................
29.1.5. Dropdowns .........................................................................................
29.1.6. Other .................................................................................................
29.2. Annotations ...................................................................................................
JBoss EL ................................................................................................................
30.1. Parameterized Expressions ............................................................................
30.1.1. Usage ................................................................................................
30.1.2. Limitations and Hints ..........................................................................
30.2. Projection ......................................................................................................
Testing Seam applications .....................................................................................
31.1. Unit testing Seam components .......................................................................
31.2. Integration testing Seam components .............................................................
31.2.1. Using mocks in integration tests ..........................................................
31.3. Integration testing Seam application user interactions ......................................
31.3.1. Configuration ......................................................................................
31.3.2. Using SeamTest with another test framework .......................................
31.3.3. Integration Testing with Mock Data ......................................................
31.3.4. Integration Testing Seam Mail .............................................................
Seam tools .............................................................................................................
32.1. jBPM designer and viewer .............................................................................
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32.1.1. Business process designer ..................................................................
32.1.2. Pageflow viewer .................................................................................
33. Seam on OC4J .......................................................................................................
33.1. Installation and operation of OC4J .................................................................
33.2. The jee5/booking example .........................................................................
33.2.1. Booking Example Dependencies .........................................................
33.2.2. Configuration file changes ...................................................................
33.2.3. Building the jee5/booking example ...................................................
33.3. Deploying the Seam application to OC4J ........................................................
33.4. Deploying an application created using seam-gen to OC4J ..............................
33.4.1. Generating a basic seam-gen application ............................................
33.4.2. Changes needed for deployment to OC4J ............................................
33.4.3. Building and deploying the seam-gen'd application to OC4J ..................
33.4.4. Extending example with reverse engineered CRUD and Drools .............
33.5. Finishing up ..................................................................................................
34. Seam on BEA's Weblogic ......................................................................................
34.1. Installation and operation of Weblogic ............................................................
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34.1.1. Installing 10.0.MP1 .............................................................................
34.1.2. Creating your Weblogic domain ...........................................................
34.1.3. How to Start/Stop/Access your domain ................................................
34.2. The jee5/booking Example .........................................................................
34.2.1. EJB3 Issues with Weblogic .................................................................
34.2.2. Getting the jee5/booking Working .....................................................
34.3. The jpa booking example ............................................................................
34.3.1. Building and deploying jpa booking example .......................................
34.3.2. What's different with Weblogic 10.x ......................................................
34.4. Deploying an application created using seam-gen on Weblogic 10.x ..................
34.4.1. Running seam-gen setup .....................................................................
34.4.2. What to change for Weblogic 10.X ......................................................
34.4.3. Building and Deploying your application ...............................................
35. Seam on IBM's Websphere ....................................................................................
35.1. Websphere environment and deployment information ......................................
35.1.1. Installation versions and tips ...............................................................
35.1.2. Required custom properties .................................................................
35.2. The jee5/booking example .........................................................................
35.2.1. Configuration file changes ...................................................................
35.2.2. Building the jee5/booking example ....................................................
35.2.3. Deploying the application to Websphere ...............................................
35.3. The jpa booking example ............................................................................
35.3.1. Building the jpa example ....................................................................
35.3.2. Deploying the jpa example .................................................................
35.3.3. Whats different for Websphere 6.1 ......................................................
35.4. Deploying an application created using seam-gen on Websphere 6.1.0.13 .........
35.4.1. Running seam-gen Setup ....................................................................
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xii
35.4.2. Changes needed for deployment to Websphere ....................................
36. Dependencies .........................................................................................................
36.1. Project Dependencies ....................................................................................
36.1.1. Core ..................................................................................................
36.1.2. RichFaces ..........................................................................................
36.1.3. Seam Mail ..........................................................................................
36.1.4. Seam PDF .........................................................................................
36.1.5. JBoss Rules .......................................................................................
36.1.6. JBPM .................................................................................................
36.1.7. GWT ..................................................................................................
36.1.8. Spring ................................................................................................
36.1.9. Groovy ...............................................................................................
36.2. Dependency Management using Maven .........................................................
495
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xiii
xiv
Introduction to JBoss Seam
Seam is an application framework for Enterprise Java. It is inspired by the following principles:
One kind of "stuff"
Seam defines a uniform component model for all business logic in your application. A
Seam component may be stateful, with the state associated with any one of several welldefined contexts, including the long-running, persistent, business process context and the
conversation context, which is preserved across multiple web requests in a user interaction.
There is no distinction between presentation tier components and business logic components
in Seam. You can layer your application according to whatever architecture you devise, rather
than being forced to shoehorn your application logic into an unnatural layering scheme forced
upon you by whatever combination of stovepipe frameworks you're using today.
Unlike plain Java EE or J2EE components, Seam components may simultaneously access
state associated with the web request and state held in transactional resources (without the
need to propagate web request state manually via method parameters). You might object that
the application layering imposed upon you by the old J2EE platform was a Good Thing. Well,
nothing stops you creating an equivalent layered architecture using Seam—the difference is
that you get to architect your own application and decide what the layers are and how they
work together.
Integrate JSF with EJB 3.0
JSF and EJB 3.0 are two of the best new features of Java EE 5. EJB3 is a brand new
component model for server side business and persistence logic. Meanwhile, JSF is a great
component model for the presentation tier. Unfortunately, neither component model is able
to solve all problems in computing by itself. Indeed, JSF and EJB3 work best used together.
But the Java EE 5 specification provides no standard way to integrate the two component
models. Fortunately, the creators of both models foresaw this situation and provided standard
extension points to allow extension and integration with other frameworks.
Seam unifies the component models of JSF and EJB3, eliminating glue code, and letting the
developer think about the business problem.
It is possible to write Seam applications where "everything" is an EJB. This may come as a
surprise if you're used to thinking of EJBs as coarse-grained, so-called "heavyweight" objects.
However, version 3.0 has completely changed the nature of EJB from the point of view of
the developer. An EJB is a fine-grained object—nothing more complex than an annotated
JavaBean. Seam even encourages you to use session beans as JSF action listeners!
On the other hand, if you prefer not to adopt EJB 3.0 at this time, you don't have to. Virtually
any Java class may be a Seam component, and Seam provides all the functionality that you
expect from a "lightweight" container, and more, for any component, EJB or otherwise.
xv
Introduction to JBoss Seam
Integrated AJAX
Seam supports the best open source JSF-based AJAX solutions: JBoss RichFaces and
ICEfaces. These solutions let you add AJAX capability to your user interface without the need
to write any JavaScript code.
Alternatively, Seam provides a built-in JavaScript remoting layer that lets you call components
asynchronously from client-side JavaScript without the need for an intermediate action layer.
You can even subscribe to server-side JMS topics and receive messages via AJAX push.
Neither of these approaches would work well, were it not for Seam's built-in concurrency and
state management, which ensures that many concurrent fine-grained, asynchronous AJAX
requests are handled safely and efficiently on the server side.
Business process as a first class construct
Optionally, Seam provides transparent business process management via jBPM. You
won't believe how easy it is to implement complex workflows, collaboration and and task
management using jBPM and Seam.
Seam even allows you to define presentation tier pageflow using the same language (jPDL)
that jBPM uses for business process definition.
JSF provides an incredibly rich event model for the presentation tier. Seam enhances this
model by exposing jBPM's business process related events via exactly the same event
handling mechanism, providing a uniform event model for Seam's uniform component model.
Declarative state management
We're all used to the concept of declarative transaction management and declarative
security from the early days of EJB. EJB 3.0 even introduces declarative persistence context
management. These are three examples of a broader problem of managing state that is
associated with a particular context, while ensuring that all needed cleanup occurs when the
context ends. Seam takes the concept of declarative state management much further and
applies it to application state. Traditionally, J2EE applications implement state management
manually, by getting and setting servlet session and request attributes. This approach to state
management is the source of many bugs and memory leaks when applications fail to clean
up session attributes, or when session data associated with different workflows collides in
a multi-window application. Seam has the potential to almost entirely eliminate this class of
bugs.
Declarative application state management is made possible by the richness of the
context model defined by Seam. Seam extends the context model defined by the servlet
spec—request, session, application—with two new contexts—conversation and business
process—that are more meaningful from the point of view of the business logic.
You'll be amazed at how many things become easier once you start using conversations. Have
you ever suffered pain dealing with lazy association fetching in an ORM solution like Hibernate
or JPA? Seam's conversation-scoped persistence contexts mean you'll rarely have to see a
LazyInitializationException. Have you ever had problems with the refresh button? The
xvi
back button? With duplicate form submission? With propagating messages across a postthen-redirect? Seam's conversation management solves these problems without you even
needing to really think about them. They're all symptoms of the broken state management
architecture that has been prevalent since the earliest days of the web.
Bijection
The notion of Inversion of Control or dependency injection exists in both JSF and EJB3, as
well as in numerous so-called "lightweight containers". Most of these containers emphasize
injection of components that implement stateless services. Even when injection of stateful
components is supported (such as in JSF), it is virtually useless for handling application
state because the scope of the stateful component cannot be defined with sufficient flexibility,
and because components belonging to wider scopes may not be injected into components
belonging to narrower scopes.
Bijection differs from IoC in that it is dynamic, contextual, and bidirectional. You can think of
it as a mechanism for aliasing contextual variables (names in the various contexts bound to
the current thread) to attributes of the component. Bijection allows auto-assembly of stateful
components by the container. It even allows a component to safely and easily manipulate the
value of a context variable, just by assigning it to an attribute of the component.
Workspace management and multi-window browsing
Seam applications let the user freely switch between multiple browser tabs, each associated
with a different, safely isolated, conversation. Applications may even take advantage of
workspace management, allowing the user to switch between conversations (workspaces) in
a single browser tab. Seam provides not only correct multi-window operation, but also multiwindow-like operation in a single window!
Prefer annotations to XML
Traditionally, the Java community has been in a state of deep confusion about precisely what
kinds of meta-information counts as configuration. J2EE and popular "lightweight" containers
have provided XML-based deployment descriptors both for things which are truly configurable
between different deployments of the system, and for any other kinds or declaration which
can not easily be expressed in Java. Java 5 annotations changed all this.
EJB 3.0 embraces annotations and "configuration by exception" as the easiest way to provide
information to the container in a declarative form. Unfortunately, JSF is still heavily dependent
on verbose XML configuration files. Seam extends the annotations provided by EJB 3.0 with
a set of annotations for declarative state management and declarative context demarcation.
This lets you eliminate the noisy JSF managed bean declarations and reduce the required
XML to just that information which truly belongs in XML (the JSF navigation rules).
Integration testing is easy
Seam components, being plain Java classes, are by nature unit testable. But for complex
applications, unit testing alone is insufficient. Integration testing has traditionally been a messy
and difficult task for Java web applications. Therefore, Seam provides for testability of Seam
applications as a core feature of the framework. You can easily write JUnit or TestNG tests
xvii
Introduction to JBoss Seam
that reproduce a whole interaction with a user, exercising all components of the system apart
from the view (the JSP or Facelets page). You can run these tests directly inside your IDE,
where Seam will automatically deploy EJB components using JBoss Embedded.
The specs ain't perfect
We think the latest incarnation of Java EE is great. But we know it's never going to be perfect.
Where there are holes in the specifications (for example, limitations in the JSF lifecycle for
GET requests), Seam fixes them. And the authors of Seam are working with the JCP expert
groups to make sure those fixes make their way back into the next revision of the standards.
There's more to a web application than serving HTML pages
Today's web frameworks think too small. They let you get user input off a form and into
your Java objects. And then they leave you hanging. A truly complete web application
framework should address problems like persistence, concurrency, asynchronicity, state
management, security, email, messaging, PDF and chart generation, workflow, wikitext
rendering, webservices, caching and more. Once you scratch the surface of Seam, you'll be
amazed at how many problems become simpler...
Seam integrates JPA and Hibernate3 for persistence, the EJB Timer Service and Quartz for
lightweight asychronicity, jBPM for workflow, JBoss Rules for business rules, Meldware Mail
for email, Hibernate Search and Lucene for full text search, JMS for messaging and JBoss
Cache for page fragment caching. Seam layers an innovative rule-based security framework
over JAAS and JBoss Rules. There's even JSF tag libraries for rendering PDF, outgoing
email, charts and wikitext. Seam components may be called synchronously as a Web Service,
asynchronously from client-side JavaScript or Google Web Toolkit or, of course, directly from
JSF.
Get started now!
Seam works in any Java EE application server, and even works in Tomcat. If your environment
supports EJB 3.0, great! If it doesn't, no problem, you can use Seam's built-in transaction
management with JPA or Hibernate3 for persistence. Or, you can deploy JBoss Embedded
in Tomcat, and get full support for EJB 3.0.
It turns out that the combination of Seam, JSF and EJB3 is the simplest way to write a complex
web application in Java. You won't believe how little code is required!
xviii
Contribute to Seam
1. Contribute to Seam
Visit SeamFramework.org [http://www.seamframework.org/Community/Contribute] to find out
how to contribute to Seam!
xix
xx
Chapter 1.
Seam Tutorial
1.1. Try the examples
In this tutorial, we'll assume that you have downloaded JBoss AS 4.2. You should also have a
copy of Seam downloaded and extracted to a work directory.
The directory structure of each example in Seam follows this pattern:
• Web pages, images and stylesheets may be found in examples/registration/view
• Resources such as deployment descriptors and data import scripts may be found in examples/
registration/resources
• Java source code may be found in examples/registration/src
• The Ant build script is examples/registration/build.xml
1.1.1. Running the examples on JBoss AS
First, make sure you have Ant correctly installed, with $ANT_HOME and $JAVA_HOME set correctly.
Next, make sure you set the location of your JBoss AS 4.2 installation in the build.properties
file in the root folder of your Seam installation. If you haven't already done so, start JBoss AS now
by typing bin/run.sh or bin/run.bat in the root directory of your JBoss installation.
Now, build and deploy the example by typing ant deploy in the examples/registration
directory.
Try it out by accessing http://localhost:8080/seam-registration/ [http://localhost:8080/
seam-registration/] with your web browser.
1.1.2. Running the examples on Tomcat
First, make sure you have Ant correctly installed, with $ANT_HOME and $JAVA_HOME set correctly.
Next, make sure you set the location of your Tomcat 6.0 installation in the build.properties file
in the root folder of your Seam installation. You will need to follow the instructions in Section 26.6.1,
“Installing Embedded JBoss” for installing JBoss Embedded on Tomcat 6.0. JBoss Embedded is
required to run the Seam demo applications on Tomcat. (However, it is possible to use Seam on
Tomcat without JBoss Embedded.)
Now, build and deploy the example by typing ant tomcat.deploy in the examples/registration
directory.
Finally, start Tomcat.
Try it out by accessing
http://localhost:8080/jboss-seam-registration/
localhost:8080/jboss-seam-registration/] with your web browser.
[http://
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Chapter 1. Seam Tutorial
When you deploy the example to Tomcat, any EJB3 components will run inside the JBoss
Embeddable EJB3 container, a complete standalone EJB3 container environment.
1.1.3. Running the example tests
Most of the examples come with a suite of TestNG integration tests. The easiest way to run the
tests is to run ant testexample inside the examples/registration directory. It is also possible
to run the tests inside your IDE using the TestNG plugin.
1.2. Your first Seam application: the registration
example
The registration example is a fairly trivial application that lets a new user store his username,
real name and password in the database. The example isn't intended to show off all of the cool
functionality of Seam. However, it demonstrates the use of an EJB3 session bean as a JSF action
listener, and basic configuration of Seam.
We'll go slowly, since we realize you might not yet be familiar with EJB 3.0.
The start page displays a very basic form with three input fields. Try filling them in and then
submitting the form. This will save a user object in the database.
1.2.1. Understanding the code
The example is implemented with two JSP pages, one entity bean and one stateless session bean.
2
Understanding the code
Let's take a look at the code, starting from the "bottom".
1.2.1.1. The entity bean: User.java
We need an EJB entity bean for user data. This class defines persistence and validation
declaratively, via annotations. It also needs some extra annotations that define the class as a
Seam component.
Example 1.1.
@Entity &lt;co id="registration-entity-annotation"/&gt;
@Name("user")
@Scope(SESSION)
@Table(name="users")
public class User implements Serializable
{
private static final long serialVersionUID = 1881413500711441951L;
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Chapter 1. Seam Tutorial
private String username;
private String password;
private String name;
public User(String name, String password, String username)
{
this.name = name;
this.password = password;
this.username = username;
}
public User() {}
@NotNull @Length(min=5, max=15)
public String getPassword()
{
return password;
}
public void setPassword(String password)
{
this.password = password;
}
@NotNull
public String getName()
{
return name;
}
public void setName(String name)
{
this.name = name;
}
@Id @NotNull @Length(min=5, max=15)
public String getUsername()
{
return username;
}
public void setUsername(String username)
4
Understanding the code
{
this.username = username;
}
}
registrationThe EJB3 standard @Entity annotation indicates that the User class is an entity bean.
entityannotation:
???
A Seam component needs a component name specified by the @Name annotation. This
name must be unique within the Seam application. When JSF asks Seam to resolve a context
variable with a name that is the same as a Seam component name, and the context variable
is currently undefined (null), Seam will instantiate that component, and bind the new instance
to the context variable. In this case, Seam will instantiate a User the first time JSF encounters
a variable named user.
Whenever Seam instantiates a component, it binds the new instance to a context variable
in the component's default context. The default context is specified using the @Scope
annotation. The User bean is a session scoped component.
The EJB standard @Table annotation indicates that the User class is mapped to the users
table.
name, password and username are the persistent attributes of the entity bean. All of our
persistent attributes define accessor methods. These are needed when this component is
used by JSF in the render response and update model values phases.
An empty constructor is both required by both the EJB specification and by Seam.
The @NotNull and @Length annotations are part of the Hibernate Validator framework. Seam
integrates Hibernate Validator and lets you use it for data validation (even if you are not using
Hibernate for persistence).
The EJB standard @Id annotation indicates the primary key attribute of the entity bean.
The most important things to notice in this example are the @Name and @Scope annotations. These
annotations establish that this class is a Seam component.
We'll see below that the properties of our User class are bound directly to JSF components and
are populated by JSF during the update model values phase. We don't need any tedious glue
code to copy data back and forth between the JSP pages and the entity bean domain model.
However, entity beans shouldn't do transaction management or database access. So we can't
use this component as a JSF action listener. For that we need a session bean.
1.2.1.2. The stateless session bean class: RegisterAction.java
Most Seam application use session beans as JSF action listeners (you can use JavaBeans instead
if you like).
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Chapter 1. Seam Tutorial
We have exactly one JSF action in our application, and one session bean method attached to it.
In this case, we'll use a stateless session bean, since all the state associated with our action is
held by the User bean.
This is the only really interesting code in the example!
Example 1.2.
@Stateless
@Name("register")
public class RegisterAction implements Register
{
@In
private User user;
@PersistenceContext
private EntityManager em;
@Logger
private Log log;
public String register()
{
List existing = em.createQuery(
"select username from User where username=#{user.username}")
.getResultList();
if (existing.size()==0)
{
em.persist(user);
log.info("Registered new user #{user.username}");
return "/registered.xhtml";
}
else
{
FacesMessages.instance().add("User #{user.username} already exists");
return null;
6
Understanding the code
}
}
}
The EJB standard @Stateless annotation marks this class as a stateless session bean.
The @In annotation marks an attribute of the bean as injected by Seam. In this case, the
attribute is injected from a context variable named user (the instance variable name).
The EJB standard @PersistenceContext annotation is used to inject the EJB3 entity
manager.
The Seam @Logger annotation is used to inject the component's Log instance.
The action listener method uses the standard EJB3 EntityManager API to interact with
the database, and returns the JSF outcome. Note that, since this is a session bean, a
transaction is automatically begun when the register() method is called, and committed
when it completes.
Notice that Seam lets you use a JSF EL expression inside EJB-QL. Under the covers, this
results in an ordinary JPA setParameter() call on the standard JPA Query object. Nice,
huh?
The Log API lets us easily display templated log messages.
JSF action listener methods return a string-valued outcome that determines what page will
be displayed next. A null outcome (or a void action listener method) redisplays the previous
page. In plain JSF, it is normal to always use a JSF navigation rule to determine the JSF view
id from the outcome. For complex application this indirection is useful and a good practice.
However, for very simple examples like this one, Seam lets you use the JSF view id as the
outcome, eliminating the requirement for a navigation rule. Note that when you use a view
id as an outcome, Seam always performs a browser redirect.
Seam provides a number of built-in components to help solve common problems. The
FacesMessages component makes it easy to display templated error or success messages.
Built-in Seam components may be obtained by injection, or by calling an instance() method.
Note that we did not explicitly specify a @Scope this time. Each Seam component type has a default
scope if not explicitly specified. For stateless session beans, the default scope is the stateless
context. Actually, all stateless session beans belong in the stateless context.
Our session bean action listener performs the business and persistence logic for our miniapplication. In more complex applications, we might need to layer the code and refactor
persistence logic into a dedicated data access component. That's perfectly trivial to do. But notice
that Seam does not force you into any particular strategy for application layering.
Furthermore, notice that our session bean has simultaneous access to context associated with
the web request (the form values in the User object, for example), and state held in transactional
resources (the EntityManager object). This is a break from traditional J2EE architectures. Again,
if you are more comfortable with the traditional J2EE layering, you can certainly implement that in
a Seam application. But for many applications, it's simply not very useful.
7
Chapter 1. Seam Tutorial
1.2.1.3. The session bean local interface: Register.java
Naturally, our session bean needs a local interface.
Example 1.3.
@Local
public interface Register
{
public String register();
}
That's the end of the Java code. Now onto the deployment descriptors.
1.2.1.4. The Seam component deployment descriptor: components.xml
If you've used many Java frameworks before, you'll be used to having to declare all your
component classes in some kind of XML file that gradually grows more and more unmanageable
as your project matures. You'll be relieved to know that Seam does not require that application
components be accompanied by XML. Most Seam applications require a very small amount of
XML that does not grow very much as the project gets bigger.
Nevertheless, it is often useful to be able to provide for some external configuration of some
components (particularly the components built in to Seam). You have a couple of options here,
but the most flexible option is to provide this configuration in a file called components.xml, located
in the WEB-INF directory. We'll use the components.xml file to tell Seam how to find our EJB
components in JNDI:
Example 1.4.
<?xml version="1.0" encoding="UTF-8"?>
<components xmlns="http://jboss.com/products/seam/components"
xmlns:core="http://jboss.com/products/seam/core"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation=
"http://jboss.com/products/seam/core http://jboss.com/products/seam/core-2.1.xsd
http://jboss.com/products/seam/components http://jboss.com/products/seam/
components-2.1.xsd">
<core:init jndi-pattern="@[email protected]"/>
</components>
8
Understanding the code
This code configures a property named jndiPattern of a built-in Seam component named
org.jboss.seam.core.init. The funny @ symbols are there because our Ant build script puts
the correct JNDI pattern in when we deploy the application.
1.2.1.5. The web deployment description: web.xml
The presentation layer for our mini-application will be deployed in a WAR. So we'll need a web
deployment descriptor.
Example 1.5.
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.5"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd">
<!-- Seam -->
<listener>
<listener-class>org.jboss.seam.servlet.SeamListener</listener-class>
</listener>
<!-- JSF -->
<listener>
<listener-class>com.sun.faces.config.ConfigureListener</listener-class>
</listener>
<context-param>
<param-name>javax.faces.DEFAULT_SUFFIX</param-name>
<param-value>.xhtml</param-value>
</context-param>
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.seam</url-pattern>
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Chapter 1. Seam Tutorial
</servlet-mapping>
<session-config>
<session-timeout>10</session-timeout>
</session-config>
</web-app>
This web.xml file configures Seam and JSF. The configuration you see here is pretty much
identical in all Seam applications.
1.2.1.6. The JSF configration: faces-config.xml
Most Seam applications use JSF views as the presentation layer. So usually we'll need facesconfig.xml. In our case, we are going to use Facelets for defining our views, so we need to tell
JSF to use Facelets as its templating engine.
Example 1.6.
<?xml version="1.0" encoding="UTF-8"?>
<faces-config version="1.2"
xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/
javaee/web-facesconfig_1_2.xsd">
<!-- Facelets support -->
<application>
<view-handler>com.sun.facelets.FaceletViewHandler</view-handler>
</application>
</faces-config>
Note that we don't need any JSF managed bean declarations! Our managed beans are annotated
Seam components. In Seam applications, the faces-config.xml is used much less often than
in plain JSF.
In fact, once you have all the basic descriptors set up, the only XML you need to write as you
add new functionality to a Seam application is orchestration: navigation rules or jBPM process
definitions. Seam takes the view that process flow and configuration data are the only things that
truly belong in XML.
In this simple example, we don't even need a navigation rule, since we decided to embed the
view id in our action code.
10
Understanding the code
1.2.1.7. The EJB deployment descriptor: ejb-jar.xml
The ejb-jar.xml file integrates Seam with EJB3, by attaching the SeamInterceptor to all
session beans in the archive.
<ejb-jar xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/ejb-jar_3_0.xsd"
version="3.0">
<interceptors>
<interceptor>
<interceptor-class>org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
</interceptor>
</interceptors>
<assembly-descriptor>
<interceptor-binding>
<ejb-name>*</ejb-name>
<interceptor-class>org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
</interceptor-binding>
</assembly-descriptor>
</ejb-jar>
1.2.1.8. The EJB persistence deployment descriptor: persistence.xml
The persistence.xml file tells the EJB persistence provider where to find the datasource, and
contains some vendor-specific settings. In this case, enables automatic schema export at startup
time.
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"
version="1.0">
<persistence-unit name="userDatabase">
<provider>org.hibernate.ejb.HibernatePersistence</provider>
<jta-data-source>java:/DefaultDS</jta-data-source>
<properties>
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<property name="hibernate.hbm2ddl.auto" value="create-drop"/>
</properties>
</persistence-unit>
</persistence>
1.2.1.9. The view: register.xhtml and registered.xhtml
The view pages for a Seam application could be implemented using any technology that supports
JSF. In this example we use Facelets, because we think it's better than JSP.
Example 1.7.
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:s="http://jboss.com/products/seam/taglib"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core">
<head>
<title>Register New User</title>
</head>
<body>
<f:view>
<h:form>
<s:validateAll>
<h:panelGrid columns="2">
Username: <h:inputText value="#{user.username}" required="true"/>
Real Name: <h:inputText value="#{user.name}" required="true"/>
Password: <h:inputSecret value="#{user.password}" required="true"/>
</h:panelGrid>
</s:validateAll>
<h:messages/>
<h:commandButton value="Register" action="#{register.register}"/>
</h:form>
</f:view>
</body>
</html>
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Understanding the code
The only thing here that is specific to Seam is the <s:validateAll> tag. This JSF component tells
JSF to validate all the contained input fields against the Hibernate Validator annotations specified
on the entity bean.
Example 1.8.
<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:f="http://java.sun.com/jsf/core">
<head>
<title>Successfully Registered New User</title>
</head>
<body>
<f:view>
Welcome, #{user.name}, you are successfully registered as #{user.username}.
</f:view>
</body>
</html>
This is a boring old Facelets page using some embedded EL. There is nothing specific to Seam
here.
1.2.1.10. The EAR deployment descriptor: application.xml
Finally, since our application is deployed as an EAR, we need a deployment descriptor there, too.
Example 1.9. registration application
<?xml version="1.0" encoding="UTF-8"?>
<application xmlns="http://java.sun.com/xml/ns/javaee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/javaee
http://java.sun.com/xml/ns/javaee/application_5.xsd"
version="5">
<display-name>Seam Registration</display-name>
<module>
<web>
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<web-uri>jboss-seam-registration.war</web-uri>
<context-root>/seam-registration</context-root>
</web>
</module>
<module>
<ejb>jboss-seam-registration.jar</ejb>
</module>
<module>
<ejb>jboss-seam.jar</ejb>
</module>
<module>
<java>jboss-el.jar</java>
</module>
</application>
This deployment descriptor links modules in the enterprise archive and binds the web application
to the context root /seam-registration.
We've now seen all the files in the entire application!
1.2.2. How it works
When the form is submitted, JSF asks Seam to resolve the variable named user. Since there is no
value already bound to that name (in any Seam context), Seam instantiates the user component,
and returns the resulting User entity bean instance to JSF after storing it in the Seam session
context.
The form input values are now validated against the Hibernate Validator constraints specified on
the User entity. If the constraints are violated, JSF redisplays the page. Otherwise, JSF binds the
form input values to properties of the User entity bean.
Next, JSF asks Seam to resolve the variable named register. Seam finds the RegisterAction
stateless session bean in the stateless context and returns it. JSF invokes the register() action
listener method.
Seam intercepts the method call and injects the User entity from the Seam session context, before
continuing the invocation.
The register() method checks if a user with the entered username already exists. If so, an error
message is queued with the FacesMessages component, and a null outcome is returned, causing
a page redisplay. The FacesMessages component interpolates the JSF expression embedded in
the message string and adds a JSF FacesMessage to the view.
If no user with that username exists, the "/registered.xhtml" outcome triggers a browser
redirect to the registered.xhtml page. When JSF comes to render the page, it asks Seam to
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Clickable lists in Seam: the messages example
resolve the variable named user and uses property values of the returned User entity from Seam's
session scope.
1.3. Clickable lists in Seam: the messages example
Clickable lists of database search results are such an important part of any online application that
Seam provides special functionality on top of JSF to make it easier to query data using EJB-QL
or HQL and display it as a clickable list using a JSF <h:dataTable>. The messages example
demonstrates this functionality.
1.3.1. Understanding the code
The message list example has one entity bean, Message, one session bean, MessageListBean
and one JSP.
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1.3.1.1. The entity bean: Message.java
The Message entity defines the title, text, date and time of a message, and a flag indicating whether
the message has been read:
Example 1.10.
@Entity
@Name("message")
@Scope(EVENT)
public class Message implements Serializable
{
private Long id;
private String title;
private String text;
private boolean read;
private Date datetime;
@Id @GeneratedValue
public Long getId() {
return id;
}
public void setId(Long id) {
this.id = id;
}
@NotNull @Length(max=100)
public String getTitle() {
return title;
}
public void setTitle(String title) {
this.title = title;
}
@NotNull @Lob
public String getText() {
return text;
}
public void setText(String text) {
this.text = text;
}
@NotNull
public boolean isRead() {
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Understanding the code
return read;
}
public void setRead(boolean read) {
this.read = read;
}
@NotNull
@Basic @Temporal(TemporalType.TIMESTAMP)
public Date getDatetime() {
return datetime;
}
public void setDatetime(Date datetime) {
this.datetime = datetime;
}
}
1.3.1.2. The stateful session bean: MessageManagerBean.java
Just like in the previous example, we have a session bean, MessageManagerBean, which defines
the action listener methods for the two buttons on our form. One of the buttons selects a message
from the list, and displays that message. The other button deletes a message. So far, this is not
so different to the previous example.
But MessageManagerBean is also responsible for fetching the list of messages the first time we
navigate to the message list page. There are various ways the user could navigate to the page,
and not all of them are preceded by a JSF action—the user might have bookmarked the page, for
example. So the job of fetching the message list takes place in a Seam factory method, instead
of in an action listener method.
We want to cache the list of messages in memory between server requests, so we will make this
a stateful session bean.
Example 1.11.
@Stateful
@Scope(SESSION)
@Name("messageManager")
public class MessageManagerBean implements Serializable, MessageManager
{
@DataModel
private List<Message> messageList;
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@DataModelSelection
@Out(required=false)
private Message message;
@PersistenceContext(type=EXTENDED)
private EntityManager em;
@Factory("messageList")
public void findMessages()
{
messageList = em.createQuery("from Message msg order by msg.datetime desc")
.getResultList();
}
public void select()
{
message.setRead(true);
}
public void delete()
{
messageList.remove(message);
em.remove(message);
message=null;
}
@Remove
public void destroy() {}
}
The @DataModel annotation exposes an attibute of type java.util.List to the JSF page
as an instance of javax.faces.model.DataModel. This allows us to use the list in a JSF
<h:dataTable> with clickable links for each row. In this case, the DataModel is made
available in a session context variable named messageList.
The @DataModelSelection annotation tells Seam to inject the List element that
corresponded to the clicked link.
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Understanding the code
The @Out annotation then exposes the selected value directly to the page. So ever time a row
of the clickable list is selected, the Message is injected to the attribute of the stateful bean,
and the subsequently outjected to the event context variable named message.
This stateful bean has an EJB3 extended persistence context. The messages retrieved in the
query remain in the managed state as long as the bean exists, so any subsequent method
calls to the stateful bean can update them without needing to make any explicit call to the
EntityManager.
The first time we navigate to the JSP page, there will be no value in the messageList context
variable. The @Factory annotation tells Seam to create an instance of MessageManagerBean
and invoke the findMessages() method to initialize the value. We call findMessages() a
factory method for messages.
The select() action listener method marks the selected Message as read, and updates it
in the database.
The delete() action listener method removes the selected Message from the database.
All stateful session bean Seam components must have a method with no parameters marked
@Remove that Seam uses to remove the stateful bean when the Seam context ends, and
clean up any server-side state.
Note that this is a session-scoped Seam component. It is associated with the user login session,
and all requests from a login session share the same instance of the component. (In Seam
applications, we usually use session-scoped components sparingly.)
1.3.1.3. The session bean local interface: MessageManager.java
All session beans have a business interface, of course.
@Local
public interface MessageManager
{
public void findMessages();
public void select();
public void delete();
public void destroy();
}
From now on, we won't show local interfaces in our code examples.
Let's skip over components.xml, persistence.xml, web.xml, ejb-jar.xml, faces-config.xml
and application.xml since they are much the same as the previous example, and go straight
to the JSP.
1.3.1.4. The view: messages.jsp
The JSP page is a straightforward use of the JSF <h:dataTable> component. Again, nothing
specific to Seam.
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Example 1.12.
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<html>
<head>
<title>Messages</title>
</head>
<body>
<f:view>
<h:form>
<h2>Message List</h2>
<h:outputText value="No messages to display"
rendered="#{messageList.rowCount==0}"/>
<h:dataTable var="msg" value="#{messageList}"
rendered="#{messageList.rowCount>0}">
<h:column>
<f:facet name="header">
<h:outputText value="Read"/>
</f:facet>
<h:selectBooleanCheckbox value="#{msg.read}" disabled="true"/>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText value="Title"/>
</f:facet>
<h:commandLink value="#{msg.title}" action="#{messageManager.select}"/>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText value="Date/Time"/>
</f:facet>
<h:outputText value="#{msg.datetime}">
<f:convertDateTime type="both" dateStyle="medium" timeStyle="short"/>
</h:outputText>
</h:column>
<h:column>
<h:commandButton value="Delete" action="#{messageManager.delete}"/>
</h:column>
</h:dataTable>
<h3><h:outputText value="#{message.title}"/></h3>
<div><h:outputText value="#{message.text}"/></div>
</h:form>
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How it works
</f:view>
</body>
</html>
1.3.2. How it works
The first time we navigate to the messages.jsp page, whether by a JSF postback (faces request)
or a direct browser GET request (non-faces request), the page will try to resolve the messageList
context variable. Since this context variable is not initialized, Seam will call the factory method
findMessages(), which performs a query against the database and results in a DataModel being
outjected. This DataModel provides the row data needed for rendering the <h:dataTable>.
When the user clicks the <h:commandLink>, JSF calls the select() action listener. Seam
intercepts this call and injects the selected row data into the message attribute of the
messageManager component. The action listener fires, marking the selected Message as read. At
the end of the call, Seam outjects the selected Message to the context variable named message.
Next, the EJB container commits the transaction, and the change to the Message is flushed to
the database. Finally, the page is re-rendered, redisplaying the message list, and displaying the
selected message below it.
If the user clicks the <h:commandButton>, JSF calls the delete() action listener. Seam intercepts
this call and injects the selected row data into the message attribute of the messageList
component. The action listener fires, removing the selected Message from the list, and also
calling remove() on the EntityManager. At the end of the call, Seam refreshes the messageList
context variable and clears the context variable named message. The EJB container commits
the transaction, and deletes the Message from the database. Finally, the page is re-rendered,
redisplaying the message list.
1.4. Seam and jBPM: the todo list example
jBPM provides sophisticated functionality for workflow and task management. To get a small taste
of how jBPM integrates with Seam, we'll show you a simple "todo list" application. Since managing
lists of tasks is such core functionality for jBPM, there is hardly any Java code at all in this example.
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1.4.1. Understanding the code
The center of this example is the jBPM process definition. There are also two JSPs and two trivial
JavaBeans (There was no reason to use session beans, since they do not access the database,
or have any other transactional behavior). Let's start with the process definition:
Example 1.13.
<process-definition name="todo">
<start-state name="start">
<transition to="todo"/>
</start-state>
<task-node name="todo">
<task name="todo" description="#{todoList.description}">
<assignment actor-id="#{actor.id}"/>
</task>
<transition to="done"/>
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Understanding the code
</task-node>
<end-state name="done"/>
</process-definition>
The <start-state> node represents the logical start of the process. When the process
starts, it immediately transitions to the todo node.
The <task-node> node represents a wait state, where business process execution pauses,
waiting for one or more tasks to be performed.
The <task> element defines a task to be performed by a user. Since there is only one task
defined on this node, when it is complete, execution resumes, and we transition to the end
state. The task gets its description from a Seam component named todoList (one of the
JavaBeans).
Tasks need to be assigned to a user or group of users when they are created. In this case,
the task is assigned to the current user, which we get from a built-in Seam component named
actor. Any Seam component may be used to perform task assignment.
The <end-state> node defines the logical end of the business process. When execution
reaches this node, the process instance is destroyed.
If we view this process definition using the process definition editor provided by JBossIDE, this
is what it looks like:
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This document defines our business process as a graph of nodes. This is the most trivial possible
business process: there is one task to be performed, and when that task is complete, the business
process ends.
The first JavaBean handles the login screen login.jsp. Its job is just to initialize the jBPM actor
id using the actor component. (In a real application, it would also need to authenticate the user.)
Example 1.14.
@Name("login")
public class Login {
@In
private Actor actor;
private String user;
public String getUser() {
return user;
}
public void setUser(String user) {
this.user = user;
}
public String login()
{
actor.setId(user);
return "/todo.jsp";
}
}
Here we see the use of @In to inject the built-in Actor component.
The JSP itself is trivial:
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h"%>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f"%>
<html>
<head>
<title>Login</title>
</head>
<body>
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Understanding the code
<h1>Login</h1>
<f:view>
<h:form>
<div>
<h:inputText value="#{login.user}"/>
<h:commandButton value="Login" action="#{login.login}"/>
</div>
</h:form>
</f:view>
</body>
</html>
The second JavaBean is responsible for starting business process instances, and ending tasks.
Example 1.15.
@Name("todoList")
public class TodoList {
private String description;
public String getDescription()
{
return description;
}
public void setDescription(String description) {
this.description = description;
}
@CreateProcess(definition="todo")
public void createTodo() {}
@StartTask @EndTask
public void done() {}
}
The description property accepts user input form the JSP page, and exposes it to the process
definition, allowing the task description to be set.
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The Seam @CreateProcess annotation creates a new jBPM process instance for the named
process definition.
The Seam @StartTask annotation starts work on a task. The @EndTask ends the task, and
allows the business process execution to resume.
In a more realistic example, @StartTask and @EndTask would not appear on the same method,
because there is usually work to be done using the application in order to complete the task.
Finally, the meat of the application is in todo.jsp:
Example 1.16.
<%@ taglib uri="http://java.sun.com/jsf/html" prefix="h" %>
<%@ taglib uri="http://java.sun.com/jsf/core" prefix="f" %>
<%@ taglib uri="http://jboss.com/products/seam/taglib" prefix="s" %>
<html>
<head>
<title>Todo List</title>
</head>
<body>
<h1>Todo List</h1>
<f:view>
<h:form id="list">
<div>
<h:outputText value="There are no todo items."
rendered="#{empty taskInstanceList}"/>
<h:dataTable value="#{taskInstanceList}" var="task"
rendered="#{not empty taskInstanceList}">
<h:column>
<f:facet name="header">
<h:outputText value="Description"/>
</f:facet>
<h:inputText value="#{task.description}"/>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText value="Created"/>
</f:facet>
<h:outputText value="#{task.taskMgmtInstance.processInstance.start}">
<f:convertDateTime type="date"/>
</h:outputText>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText value="Priority"/>
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Understanding the code
</f:facet>
<h:inputText value="#{task.priority}" style="width: 30"/>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText value="Due Date"/>
</f:facet>
<h:inputText value="#{task.dueDate}" style="width: 100">
<f:convertDateTime type="date" dateStyle="short"/>
</h:inputText>
</h:column>
<h:column>
<s:button value="Done" action="#{todoList.done}" taskInstance="#{task}"/>
</h:column>
</h:dataTable>
</div>
<div>
<h:messages/>
</div>
<div>
<h:commandButton value="Update Items" action="update"/>
</div>
</h:form>
<h:form id="new">
<div>
<h:inputText value="#{todoList.description}"/>
<h:commandButton value="Create New Item" action="#{todoList.createTodo}"/>
</div>
</h:form>
</f:view>
</body>
</html>
Let's take this one piece at a time.
The page renders a list of tasks, which it gets from a built-in Seam component named
taskInstanceList. The list is defined inside a JSF form.
Example 1.17.
<h:form id="list">
<div>
<h:outputText value="There are no todo items." rendered="#{empty taskInstanceList}"/>
<h:dataTable value="#{taskInstanceList}" var="task"
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rendered="#{not empty taskInstanceList}">
...
</h:dataTable>
</div>
</h:form>
Each element of the list is an instance of the jBPM class TaskInstance. The following code simply
displays the interesting properties of each task in the list. For the description, priority and due
date, we use input controls, to allow the user to update these values.
<h:column>
<f:facet name="header">
<h:outputText value="Description"/>
</f:facet>
<h:inputText value="#{task.description}"/>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText value="Created"/>
</f:facet>
<h:outputText value="#{task.taskMgmtInstance.processInstance.start}">
<f:convertDateTime type="date"/>
</h:outputText>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText value="Priority"/>
</f:facet>
<h:inputText value="#{task.priority}" style="width: 30"/>
</h:column>
<h:column>
<f:facet name="header">
<h:outputText value="Due Date"/>
</f:facet>
<h:inputText value="#{task.dueDate}" style="width: 100">
<f:convertDateTime type="date" dateStyle="short"/>
</h:inputText>
</h:column>
This button ends the task by calling the action method annotated @StartTask @EndTask. It passes
the task id to Seam as a request parameter:
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How it works
<h:column>
<s:button value="Done" action="#{todoList.done}" taskInstance="#{task}"/>
</h:column>
(Note that this is using a Seam <s:button> JSF control from the seam-ui.jar package.)
This button is used to update the properties of the tasks. When the form is submitted, Seam and
jBPM will make any changes to the tasks persistent. There is no need for any action listener
method:
<h:commandButton value="Update Items" action="update"/>
A second form on the page is used to create new items, by calling the action method annotated
@CreateProcess.
<h:form id="new">
<div>
<h:inputText value="#{todoList.description}"/>
<h:commandButton value="Create New Item" action="#{todoList.createTodo}"/>
</div>
</h:form>
There are several other files needed for the example, but they are just standard jBPM and Seam
configuration and not very interesting.
1.4.2. How it works
TODO
1.5. Seam pageflow: the numberguess example
For Seam applications with relatively freeform (ad hoc) navigation, JSF/Seam navigation rules are
a perfectly good way to define the page flow. For applications with a more constrained style of
navigation, especially for user interfaces which are more stateful, navigation rules make it difficult
to really understand the flow of the system. To understand the flow, you need to piece it together
from the view pages, the actions and the navigation rules.
Seam allows you to use a jPDL process definition to define pageflow. The simple number guessing
example shows how this is done.
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1.5.1. Understanding the code
The example is implemented using one JavaBean, three JSP pages and a jPDL pageflow
definition. Let's begin with the pageflow:
Example 1.18.
<pageflow-definition
xmlns="http://jboss.com/products/seam/pageflow"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://jboss.com/products/seam/pageflow
http://jboss.com/products/seam/pageflow-2.1.xsd"
name="numberGuess">
<start-page name="displayGuess" view-id="/numberGuess.jspx">
<redirect/>
<transition name="guess" to="evaluateGuess">
<action expression="#{numberGuess.guess}"/>
</transition>
<transition name="giveup" to="giveup"/>
</start-page>
<decision name="evaluateGuess" expression="#{numberGuess.correctGuess}">
<transition name="true" to="win"/>
<transition name="false" to="evaluateRemainingGuesses"/>
</decision>
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Understanding the code
<decision name="evaluateRemainingGuesses" expression="#{numberGuess.lastGuess}">
<transition name="true" to="lose"/>
<transition name="false" to="displayGuess"/>
</decision>
<page name="giveup" view-id="/giveup.jspx">
<redirect/>
<transition name="yes" to="lose"/>
<transition name="no" to="displayGuess"/>
</page>
<page name="win" view-id="/win.jspx">
<redirect/>
<end-conversation/>
</page>
<page name="lose" view-id="/lose.jspx">
<redirect/>
<end-conversation/>
</page>
</pageflow-definition>
The <page> element defines a wait state where the system displays a particular JSF view
and waits for user input. The view-id is the same JSF view id used in plain JSF navigation
rules. The redirect attribute tells Seam to use post-then-redirect when navigating to the
page. (This results in friendly browser URLs.)
The <transition> element names a JSF outcome. The transition is triggered when a JSF
action results in that outcome. Execution will then proceed to the next node of the pageflow
graph, after invocation of any jBPM transition actions.
A transition <action> is just like a JSF action, except that it occurs when a jBPM transition
occurs. The transition action can invoke any Seam component.
A <decision> node branches the pageflow, and determines the next node to execute by
evaluating a JSF EL expression.
Here is what the pageflow looks like in the JBoss Developer Studio pageflow editor:
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Now that we have seen the pageflow, it is very, very easy to understand the rest of the application!
Here is the main page of the application, numberGuess.jspx:
Example 1.19.
<<?xml version="1.0"?>
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:s="http://jboss.com/products/seam/taglib"
xmlns="http://www.w3.org/1999/xhtml"
version="2.0">
<jsp:output doctype-root-element="html"
doctype-public="-//W3C//DTD XHTML 1.0 Transitional//EN"
doctype-system="http://www.w3c.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"/>
<jsp:directive.page contentType="text/html"/>
<html>
<head>
<title>Guess a number...</title>
<link href="niceforms.css" rel="stylesheet" type="text/css" />
<script language="javascript" type="text/javascript" src="niceforms.js" />
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Understanding the code
</head>
<body>
<h1>Guess a number...</h1>
<f:view>
<h:form styleClass="niceform">
<div>
<h:messages globalOnly="true"/>
<h:outputText value="Higher!"
rendered="#{numberGuess.randomNumber gt numberGuess.currentGuess}"/>
<h:outputText value="Lower!"
rendered="#{numberGuess.randomNumber lt numberGuess.currentGuess}"/>
</div>
<div>
I'm thinking of a number between
<h:outputText value="#{numberGuess.smallest}"/> and
<h:outputText value="#{numberGuess.biggest}"/>. You have
<h:outputText value="#{numberGuess.remainingGuesses}"/> guesses.
</div>
<div>
Your guess:
<h:inputText value="#{numberGuess.currentGuess}" id="inputGuess"
required="true" size="3"
rendered="#{(numberGuess.biggest-numberGuess.smallest) gt 20}">
<f:validateLongRange maximum="#{numberGuess.biggest}"
minimum="#{numberGuess.smallest}"/>
</h:inputText>
<h:selectOneMenu value="#{numberGuess.currentGuess}"
id="selectGuessMenu" required="true"
rendered="#{(numberGuess.biggest-numberGuess.smallest) le 20 and
(numberGuess.biggest-numberGuess.smallest) gt 4}">
<s:selectItems value="#{numberGuess.possibilities}" var="i" label="#{i}"/>
</h:selectOneMenu>
<h:selectOneRadio value="#{numberGuess.currentGuess}" id="selectGuessRadio"
required="true"
rendered="#{(numberGuess.biggest-numberGuess.smallest) le 4}">
<s:selectItems value="#{numberGuess.possibilities}" var="i" label="#{i}"/>
</h:selectOneRadio>
<h:commandButton value="Guess" action="guess"/>
<s:button value="Cheat" view="/confirm.jspx"/>
<s:button value="Give up" action="giveup"/>
</div>
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Chapter 1. Seam Tutorial
<div>
<h:message for="inputGuess" style="color: red"/>
</div>
</h:form>
</f:view>
</body>
</html>
</jsp:root>
Notice how the command button names the guess transition instead of calling an action directly.
The win.jspx page is predictable:
Example 1.20.
<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
xmlns="http://www.w3.org/1999/xhtml"
version="2.0">
<jsp:output doctype-root-element="html"
doctype-public="-//W3C//DTD XHTML 1.0 Transitional//EN"
doctype-system="http://www.w3c.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"/>
<jsp:directive.page contentType="text/html"/>
<html>
<head>
<title>You won!</title>
<link href="niceforms.css" rel="stylesheet" type="text/css" />
</head>
<body>
<h1>You won!</h1>
<f:view>
Yes, the answer was <h:outputText value="#{numberGuess.currentGuess}" />.
It took you <h:outputText value="#{numberGuess.guessCount}" /> guesses.
<h:outputText value="But you cheated, so it doesn't count!"
rendered="#{numberGuess.cheat}"/>
Would you like to <a href="numberGuess.seam">play again</a>?
</f:view>
</body>
</html>
</jsp:root>
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Understanding the code
As is lose.jspx (which I can't be bothered copy/pasting). Finally, the JavaBean Seam
component:
Example 1.21.
@Name("numberGuess")
@Scope(ScopeType.CONVERSATION)
public class NumberGuess implements Serializable {
private int randomNumber;
private Integer currentGuess;
private int biggest;
private int smallest;
private int guessCount;
private int maxGuesses;
private boolean cheated;
@Create
public void begin()
{
randomNumber = new Random().nextInt(100);
guessCount = 0;
biggest = 100;
smallest = 1;
}
public void setCurrentGuess(Integer guess)
{
this.currentGuess = guess;
}
public Integer getCurrentGuess()
{
return currentGuess;
}
public void guess()
{
if (currentGuess>randomNumber)
{
biggest = currentGuess - 1;
}
if (currentGuess<randomNumber)
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Chapter 1. Seam Tutorial
{
smallest = currentGuess + 1;
}
guessCount ++;
}
public boolean isCorrectGuess()
{
return currentGuess==randomNumber;
}
public int getBiggest()
{
return biggest;
}
public int getSmallest()
{
return smallest;
}
public int getGuessCount()
{
return guessCount;
}
public boolean isLastGuess()
{
return guessCount==maxGuesses;
}
public int getRemainingGuesses() {
return maxGuesses-guessCount;
}
public void setMaxGuesses(int maxGuesses) {
this.maxGuesses = maxGuesses;
}
public int getMaxGuesses() {
return maxGuesses;
}
public int getRandomNumber() {
36
Understanding the code
return randomNumber;
}
public void cheated()
{
cheated = true;
}
public boolean isCheat() {
return cheated;
}
public List<Integer> getPossibilities()
{
List<Integer> result = new ArrayList<Integer>();
for(int i=smallest; i<=biggest; i++) result.add(i);
return result;
}
}
The first time a JSP page asks for a numberGuess component, Seam will create a new one
for it, and the @Create method will be invoked, allowing the component to initialize itself.
The pages.xml file starts a Seam conversation (much more about that later), and specifies the
pageflow definition to use for the conversation's page flow.
<?xml version="1.0" encoding="UTF-8"?>
<pages xmlns="http://jboss.com/products/seam/pages"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://jboss.com/products/seam/pages http://jboss.com/products/
seam/pages-2.1.xsd">
<page view-id="/numberGuess.jspx">
<begin-conversation join="true" pageflow="numberGuess"/>
</page>
<page view-id="/confirm.jspx">
<begin-conversation nested="true" pageflow="cheat"/>
</page>
</pages>
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As you can see, this Seam component is pure business logic! It doesn't need to know anything at
all about the user interaction flow. This makes the component potentially more reuseable.
1.5.2. How it works
TODO
1.6. A complete Seam application: the Hotel Booking
example
1.6.1. Introduction
The booking application is a complete hotel room reservation system incorporating the following
features:
• User registration
• Login
• Logout
• Set password
• Hotel search
• Hotel selection
• Room reservation
• Reservation confirmation
• Existing reservation list
38
Introduction
The booking application uses JSF, EJB 3.0 and Seam, together with Facelets for the view. There
is also a port of this application to JSF, Facelets, Seam, JavaBeans and Hibernate3.
One of the things you'll notice if you play with this application for long enough is that it is extremely
robust. You can play with back buttons and browser refresh and opening multiple windows and
entering nonsensical data as much as you like and you will find it very difficult to make the
39
Chapter 1. Seam Tutorial
application crash. You might think that we spent weeks testing and fixing bugs to achive this.
Actually, this is not the case. Seam was designed to make it very straightforward to build robust
web applications and a lot of robustness that you are probably used to having to code yourself
comes naturally and automatically with Seam.
As you browse the sourcecode of the example application, and learn how the application works,
observe how the declarative state management and integrated validation has been used to
achieve this robustness.
1.6.2. Overview of the booking example
The project structure is identical to the previous one, to install and deploy this application, please
refer to Section 1.1, “Try the examples”. Once you've successfully started the application, you
can access it by pointing your browser to http://localhost:8080/seam-booking/ [http://
localhost:8080/seam-booking/]
Just nine classes (plus six session beans local interfaces) where used to implement this
application. Six session bean action listeners contain all the business logic for the listed features.
• BookingListAction retrieves existing bookings for the currently logged in user.
• ChangePasswordAction updates the password of the currently logged in user.
• HotelBookingAction implements the core functionality of the application: hotel room
searching, selection, booking and booking confirmation. This functionality is implemented as a
conversation, so this is the most interesting class in the application.
• RegisterAction registers a new system user.
Three entity beans implement the application's persistent domain model.
• Hotel is an entity bean that represent a hotel
• Booking is an entity bean that represents an existing booking
• User is an entity bean to represents a user who can make hotel bookings
1.6.3. Understanding Seam conversations
We encourage you browse the sourcecode at your pleasure. In this tutorial we'll concentrate
upon one particular piece of functionality: hotel search, selection, booking and confirmation. From
the point of view of the user, everything from selecting a hotel to confirming a booking is one
continuous unit of work, a conversation. Searching, however, is not part of the conversation. The
user can select multiple hotels from the same search results page, in different browser tabs.
Most web application architectures have no first class construct to represent a conversation. This
causes enormous problems managing state associated with the conversation. Usually, Java web
applications use a combination of two techniques: first, some state is thrown into the HttpSession;
second, persistable state is flushed to the database after every request, and reconstructed from
the database at the beginning of each new request.
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Understanding Seam conversations
Since the database is the least scalable tier, this often results in an utterly unacceptable lack of
scalability. Added latency is also a problem, due to the extra traffic to and from the database on
every request. To reduce this redundant traffic, Java applications often introduce a data (secondlevel) cache that keeps commonly accessed data between requests. This cache is necessarily
inefficient, because invalidation is based upon an LRU policy instead of being based upon when
the user has finished working with the data. Furthermore, because the cache is shared between
many concurrent transactions, we've introduced a whole raft of problem's associated with keeping
the cached state consistent with the database.
Now consider the state held in the HttpSession. By very careful programming, we might be able
to control the size of the session data. This is a lot more difficult than it sounds, since web browsers
permit ad hoc non-linear navigation. But suppose we suddenly discover a system requirement
that says that a user is allowed to have mutiple concurrent conversations, halfway through the
development of the system (this has happened to me). Developing mechanisms to isolate session
state associated with different concurrent conversations, and incorporating failsafes to ensure
that conversation state is destroyed when the user aborts one of the conversations by closing a
browser window or tab is not for the faint hearted (I've implemented this stuff twice so far, once
for a client application, once for Seam, but I'm famously psychotic).
Now there is a better way.
Seam introduces the conversation context as a first class construct. You can safely keep
conversational state in this context, and be assured that it will have a well-defined lifecycle. Even
better, you won't need to be continually pushing data back and forth between the application
server and the database, since the conversation context is a natural cache of data that the user
is currently working with.
Usually, the components we keep in the conversation context are stateful session beans. (We can
also keep entity beans and JavaBeans in the conversation context.) There is an ancient canard in
the Java community that stateful session beans are a scalability killer. This may have been true
in 1998 when WebFoobar 1.0 was released. It is no longer true today. Application servers like
JBoss AS have extremely sophisticated mechanisms for stateful session bean state replication.
(For example, the JBoss EJB3 container performs fine-grained replication, replicating only those
bean attribute values which actually changed.) Note that all the traditional technical arguments
for why stateful beans are inefficient apply equally to the HttpSession, so the practice of shifting
state from business tier stateful session bean components to the web session to try and improve
performance is unbelievably misguided. It is certainly possible to write unscalable applications
using stateful session beans, by using stateful beans incorrectly, or by using them for the wrong
thing. But that doesn't mean you should never use them. Anyway, Seam guides you toward a safe
usage model. Welcome to 2005.
OK, I'll stop ranting now, and get back to the tutorial.
The booking example application shows how stateful components with different scopes can
collaborate together to achieve complex behaviors. The main page of the booking application
allows the user to search for hotels. The search results are kept in the Seam session scope. When
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Chapter 1. Seam Tutorial
the user navigates to one of these hotels, a conversation begins, and a conversation scoped
component calls back to the session scoped component to retrieve the selected hotel.
The booking example also demonstrates the use of RichFaces Ajax to implement rich client
behavior without the use of handwritten JavaScript.
The search functionality is implemented using a session-scope stateful session bean, similar to
the one we saw in the message list example above.
Example 1.22.
@Stateful
@Name("hotelSearch")
@Scope(ScopeType.SESSION)
@Restrict("#{identity.loggedIn}")
public class HotelSearchingAction implements HotelSearching
{
@PersistenceContext
private EntityManager em;
private String searchString;
private int pageSize = 10;
private int page;
@DataModel
private List<Hotel> hotels;
public void find()
{
page = 0;
queryHotels();
}
public void nextPage()
{
page++;
queryHotels();
}
private void queryHotels()
{
hotels =
em.createQuery("select h from Hotel h where lower(h.name) like #{pattern} " +
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Understanding Seam conversations
"or lower(h.city) like #{pattern} " +
"or lower(h.zip) like #{pattern} " +
"or lower(h.address) like #{pattern}")
.setMaxResults(pageSize)
.setFirstResult( page * pageSize )
.getResultList();
}
public boolean isNextPageAvailable()
{
return hotels!=null && hotels.size()==pageSize;
}
public int getPageSize() {
return pageSize;
}
public void setPageSize(int pageSize) {
this.pageSize = pageSize;
}
@Factory(value="pattern", scope=ScopeType.EVENT)
public String getSearchPattern()
{
return searchString==null ?
"%" : '%' + searchString.toLowerCase().replace('*', '%') + '%';
}
public String getSearchString()
{
return searchString;
}
public void setSearchString(String searchString)
{
this.searchString = searchString;
}
@Remove
public void destroy() {}
}
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Chapter 1. Seam Tutorial
The EJB standard @Stateful annotation identifies this class as a stateful session bean.
Stateful session beans are scoped to the conversation context by default.
The @Restrict annotation applies a security restriction to the component. It restricts access
to the component allowing only logged-in users. The security chapter explains more about
security in Seam.
The @DataModel annotation exposes a List as a JSF ListDataModel. This makes it easy
to implement clickable lists for search screens. In this case, the list of hotels is exposed to
the page as a ListDataModel in the conversation variable named hotels.
The EJB standard @Remove annotation specifies that a stateful session bean should be
removed and its state destroyed after invocation of the annotated method. In Seam, all
stateful session beans must define a method with no parameters marked @Remove. This
method will be called when Seam destroys the session context.
The main page of the application is a Facelets page. Let's look at the fragment which relates to
searching for hotels:
Example 1.23.
<div class="section">
<span class="errors">
<h:messages globalOnly="true"/>
</span>
<h1>Search Hotels</h1>
<h:form id="searchCriteria">
<fieldset>
<h:inputText id="searchString" value="#{hotelSearch.searchString}"
style="width: 165px;">
<a:support event="onkeyup" actionListener="#{hotelSearch.find}"
reRender="searchResults" />
</h:inputText>
&#160;
<a:commandButton id="findHotels" value="Find Hotels" action="#{hotelSearch.find}"
reRender="searchResults"/>
&#160;
<a:status>
<f:facet name="start">
<h:graphicImage value="/img/spinner.gif"/>
</f:facet>
</a:status>
<br/>
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Understanding Seam conversations
<h:outputLabel for="pageSize">Maximum results:</h:outputLabel>&#160;
<h:selectOneMenu value="#{hotelSearch.pageSize}" id="pageSize">
<f:selectItem itemLabel="5" itemValue="5"/>
<f:selectItem itemLabel="10" itemValue="10"/>
<f:selectItem itemLabel="20" itemValue="20"/>
</h:selectOneMenu>
</fieldset>
</h:form>
</div>
<a:outputPanel id="searchResults">
<div class="section">
<h:outputText value="No Hotels Found"
rendered="#{hotels != null and hotels.rowCount==0}"/>
<h:dataTable id="hotels" value="#{hotels}" var="hot"
rendered="#{hotels.rowCount>0}">
<h:column>
<f:facet name="header">Name</f:facet>
#{hot.name}
</h:column>
<h:column>
<f:facet name="header">Address</f:facet>
#{hot.address}
</h:column>
<h:column>
<f:facet name="header">City, State</f:facet>
#{hot.city}, #{hot.state}, #{hot.country}
</h:column>
<h:column>
<f:facet name="header">Zip</f:facet>
#{hot.zip}
</h:column>
<h:column>
<f:facet name="header">Action</f:facet>
<s:link id="viewHotel" value="View Hotel"
action="#{hotelBooking.selectHotel(hot)}"/>
</h:column>
</h:dataTable>
<s:link value="More results" action="#{hotelSearch.nextPage}"
rendered="#{hotelSearch.nextPageAvailable}"/>
</div>
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Chapter 1. Seam Tutorial
</a:outputPanel>
The RichFaces Ajax <a:support> tag allows a JSF action event listener to be called by
asynchronous XMLHttpRequest when a JavaScript event like onkeyup occurs. Even better,
the reRender attribute lets us render a fragment of the JSF page and perform a partial page
update when the asynchronous response is received.
The RichFaces Ajax <a:status> tag lets us display a cheesy annimated image while we
wait for asynchronous requests to return.
The RichFaces Ajax <a:outputPanel> tag defines a region of the page which can be rerendered by an asynchronous request.
The Seam <s:link> tag lets us attach a JSF action listener to an ordinary (non-JavaScript)
HTML link. The advantage of this over the standard JSF <h:commandLink> is that it preserves
the operation of "open in new window" and "open in new tab". Also notice that we use
a method binding with a parameter: #{hotelBooking.selectHotel(hot)}. This is not
possible in the standard Unified EL, but Seam provides an extension to the EL that lets you
use parameters on any method binding expression.
If you're wondering how navigation occurs, you can find all the rules in WEB-INF/pages.xml;
this is discussed in Section 6.6, “Navigation”.
This page displays the search results dynamically as we type, and lets us choose a hotel and pass
it to the selectHotel() method of the HotelBookingAction, which is where the really interesting
stuff is going to happen.
Now let's see how the booking example application uses a conversation-scoped stateful session
bean to achieve a natural cache of persistent data related to the conversation. The following code
example is pretty long. But if you think of it as a list of scripted actions that implement the various
steps of the conversation, it's understandable. Read the class from top to bottom, as if it were
a story.
Example 1.24.
@Stateful
@Name("hotelBooking")
@Restrict("#{identity.loggedIn}")
public class HotelBookingAction implements HotelBooking
{
@PersistenceContext(type=EXTENDED)
private EntityManager em;
@In
private User user;
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Understanding Seam conversations
@In(required=false) @Out
private Hotel hotel;
@In(required=false)
@Out(required=false)
private Booking booking;
@In
private FacesMessages facesMessages;
@In
private Events events;
@Logger
private Log log;
private boolean bookingValid;
@Begin
public void selectHotel(Hotel selectedHotel)
{
hotel = em.merge(selectedHotel);
}
public void bookHotel()
{
booking = new Booking(hotel, user);
Calendar calendar = Calendar.getInstance();
booking.setCheckinDate( calendar.getTime() );
calendar.add(Calendar.DAY_OF_MONTH, 1);
booking.setCheckoutDate( calendar.getTime() );
}
public void setBookingDetails()
{
Calendar calendar = Calendar.getInstance();
calendar.add(Calendar.DAY_OF_MONTH, -1);
if ( booking.getCheckinDate().before( calendar.getTime() ) )
{
facesMessages.addToControl("checkinDate", "Check in date must be a future date");
bookingValid=false;
}
else if ( !booking.getCheckinDate().before( booking.getCheckoutDate() ) )
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Chapter 1. Seam Tutorial
{
facesMessages.addToControl("checkoutDate",
"Check out date must be later than check in date");
bookingValid=false;
}
else
{
bookingValid=true;
}
}
public boolean isBookingValid()
{
return bookingValid;
}
@End
public void confirm()
{
em.persist(booking);
facesMessages.add("Thank you, #{user.name}, your confimation number " +
" for #{hotel.name} is #{booki g.id}");
log.info("New booking: #{booking.id} for #{user.username}");
events.raiseTransactionSuccessEvent("bookingConfirmed");
}
@End
public void cancel() {}
@Remove
public void destroy() {}
This bean uses an EJB3 extended persistence context, so that any entity instances remain
managed for the whole lifecycle of the stateful session bean.
The @Out annotation declares that an attribute value is outjected to a context variable after
method invocations. In this case, the context variable named hotel will be set to the value
of the hotel instance variable after every action listener invocation completes.
The @Begin annotation specifies that the annotated method begins a long-running
conversation, so the current conversation context will not be destroyed at the end of the
request. Instead, it will be reassociated with every request from the current window, and
destroyed either by timeout due to conversation inactivity or invocation of a matching @End
method.
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The Seam UI control library
The @End annotation specifies that the annotated method ends the current long-running
conversation, so the current conversation context will be destroyed at the end of the request.
This EJB remove method will be called when Seam destroys the conversation context. Don't
forget to define this method!
HotelBookingAction contains all the action listener methods that implement selection, booking
and booking confirmation, and holds state related to this work in its instance variables. We think
you'll agree that this code is much cleaner and simpler than getting and setting HttpSession
attributes.
Even better, a user can have multiple isolated conversations per login session. Try it! Log in, run
a search, and navigate to different hotel pages in multiple browser tabs. You'll be able to work
on creating two different hotel reservations at the same time. If you leave any one conversation
inactive for long enough, Seam will eventually time out that conversation and destroy its state. If,
after ending a conversation, you backbutton to a page of that conversation and try to perform an
action, Seam will detect that the conversation was already ended, and redirect you to the search
page.
1.6.4. The Seam UI control library
If you check inside the WAR file for the booking application, you'll find seam-ui.jar in the WEBINF/lib directory. This package contains a number of JSF custom controls that integrate with
Seam. The booking application uses the <s:link> control for navigation from the search screen
to the hotel page:
<s:link value="View Hotel" action="#{hotelBooking.selectHotel(hot)}"/>
The use of <s:link> here allows us to attach an action listener to a HTML link without breaking
the browser's "open in new window" feature. The standard JSF <h:commandLink> does not work
with "open in new window". We'll see later that <s:link> also offers a number of other useful
features, including conversation propagation rules.
The booking application uses some other Seam and RichFaces Ajax controls, especially on
the /book.xhtml page. We won't get into the details of those controls here, but if you want
to understand this code, please refer to the chapter covering Seam's functionality for JSF form
validation.
1.6.5. The Seam Debug Page
The WAR also includes seam-debug.jar. The Seam debug page will be availabled if this jar is
deployed in WEB-INF/lib, along with the Facelets, and if you set the debug property of the init
component:
<core:init jndi-pattern="@[email protected]" debug="true"/>
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Chapter 1. Seam Tutorial
This page lets you browse and inspect the Seam components in any of the Seam contexts
associated with your current login session. Just point your browser at http://localhost:8080/
seam-booking/debug.seam [http://localhost:8080/seam-booking/debug.seam].
1.7. A complete application featuring Seam and jBPM:
the DVD Store example
The DVD Store demo application shows the practical usage of jBPM for both task management
and pageflow.
The user screens take advantage of a jPDL pageflow to implement searching and shopping cart
functionality.
50
A complete application featuring Seam and
jBPM: the DVD Store example
The administration screens take use jBPM to manage the approval and shipping cycle for
orders. The business process may even be changed dynamically, by selecting a different process
definition!
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Chapter 1. Seam Tutorial
TODO
Look in the dvdstore directory.
1.8. An example of Seam with Hibernate: the Hibernate
Booking example
The Hibernate Booking demo is a straight port of the Booking demo to an alternative architecture
that uses Hibernate for persistence and JavaBeans instead of session beans.
TODO
Look in the hibernate directory.
52
A RESTful Seam application: the Blog example
1.9. A RESTful Seam application: the Blog example
Seam makes it very easy to implement applications which keep state on the server-side.
However, server-side state is not always appropriate, especially in for functionality that serves
up content. For this kind of problem we often need to let the user bookmark pages and have a
relatively stateless server, so that any page can be accessed at any time, via the bookmark. The
Blog example shows how to a implement RESTful application using Seam. Every page of the
application can be bookmarked, including the search results page.
The Blog example demonstrates the use of "pull"-style MVC, where instead of using action listener
methods to retrieve data and prepare the data for the view, the view pulls data from components
as it is being rendered.
1.9.1. Using "pull"-style MVC
This snippet from the index.xhtml facelets page displays a list of recent blog entries:
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Chapter 1. Seam Tutorial
Example 1.25.
<h:dataTable value="#{blog.recentBlogEntries}" var="blogEntry" rows="3">
<h:column>
<div class="blogEntry">
<h3>#{blogEntry.title}</h3>
<div>
<h:outputText escape="false"
value="#{blogEntry.excerpt==null ? blogEntry.body : blogEntry.excerpt}"/>
</div>
<p>
<h:outputLink value="entry.seam" rendered="#{blogEntry.excerpt!=null}">
<f:param name="blogEntryId" value="#{blogEntry.id}"/>
Read more...
</h:outputLink>
</p>
<p>
[Posted on
<h:outputText value="#{blogEntry.date}">
<f:convertDateTime timeZone="#{blog.timeZone}"
locale="#{blog.locale}" type="both"/>
</h:outputText>]
&#160;
<h:outputLink value="entry.seam">[Link]
<f:param name="blogEntryId" value="#{blogEntry.id}"/>
</h:outputLink>
</p>
</div>
</h:column>
</h:dataTable>
If we navigate to this page from a bookmark, how does the data used by the <h:dataTable>
actually get initialized? Well, what happens is that the Blog is retrieved lazily—"pulled"—when
needed, by a Seam component named blog. This is the opposite flow of control to what is usual
in traditional web action-based frameworks like Struts.
Example 1.26.
@Name("blog")
@Scope(ScopeType.STATELESS)
@AutoCreate
public class BlogService
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Bookmarkable search results page
{
@In EntityManager entityManager;
@Unwrap
public Blog getBlog()
{
return (Blog) entityManager.createQuery("select distinct b from Blog b left join fetch
b.blogEntries")
.setHint("org.hibernate.cacheable", true)
.getSingleResult();
}
}
This component uses a seam-managed persistence context. Unlike the other examples
we've seen, this persistence context is managed by Seam, instead of by the EJB3 container.
The persistence context spans the entire web request, allowing us to avoid any exceptions
that occur when accessing unfetched associations in the view.
The @Unwrap annotation tells Seam to provide the return value of the method—the
Blog—instead of the actual BlogService component to clients. This is the Seam manager
component pattern.
This is good so far, but what about bookmarking the result of form submissions, such as a search
results page?
1.9.2. Bookmarkable search results page
The blog example has a tiny form in the top right of each page that allows the user to search for blog
entries. This is defined in a file, menu.xhtml, included by the facelets template, template.xhtml:
Example 1.27.
<div id="search">
<h:form>
<h:inputText value="#{searchAction.searchPattern}"/>
<h:commandButton value="Search" action="/search.xhtml"/>
</h:form>
</div>
To implement a bookmarkable search results page, we need to perform a browser redirect after
processing the search form submission. Because we used the JSF view id as the action outcome,
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Chapter 1. Seam Tutorial
Seam automatically redirects to the view id when the form is submitted. Alternatively, we could
have defined a navigation rule like this:
<navigation-rule>
<navigation-case>
<from-outcome>searchResults</from-outcome>
<to-view-id>/search.xhtml</to-view-id>
<redirect/>
</navigation-case>
</navigation-rule>
Then the form would have looked like this:
<div id="search">
<h:form>
<h:inputText value="#{searchAction.searchPattern}"/>
<h:commandButton value="Search" action="searchResults"/>
</h:form>
</div>
But when we redirect, we need to include the values submitted with the form as
request parameters, to get a bookmarkable URL like http://localhost:8080/seam-blog/
search.seam?searchPattern=seam. JSF does not provide an easy way to do this, but Seam
does. We use a Seam page parameter, defined in WEB-INF/pages.xml:
Example 1.28.
<pages>
<page view-id="/search.xhtml">
<param name="searchPattern" value="#{searchService.searchPattern}"/>
</page>
...
</pages>
This tells Seam to include the value of #{searchService.searchPattern} as a request
parameter named searchPattern when redirecting to the page, and then re-apply the value of
that parameter to the model before rendering the page.
The redirect takes us to the search.xhtml page:
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Bookmarkable search results page
<h:dataTable value="#{searchResults}" var="blogEntry">
<h:column>
<div>
<h:outputLink value="entry.seam">
<f:param name="blogEntryId" value="#{blogEntry.id}"/>
#{blogEntry.title}
</h:outputLink>
posted on
<h:outputText value="#{blogEntry.date}">
<f:convertDateTime timeZone="#{blog.timeZone}" locale="#{blog.locale}" type="both"/>
</h:outputText>
</div>
</h:column>
</h:dataTable>
Which again uses "pull"-style MVC to retrieve the actual search results:
@Name("searchService")
public class SearchService
{
@In
private EntityManager entityManager;
private String searchPattern;
@Factory("searchResults")
public List<BlogEntry> getSearchResults()
{
if (searchPattern==null)
{
return null;
}
else
{
return entityManager.createQuery("select be from BlogEntry be "" +
"where lower(be.title) like :searchPattern " +
"lower(be.body) like :searchPattern order by be.date desc")
.setParameter( "searchPattern", getSqlSearchPattern() )
.setMaxResults(100)
.getResultList();
}
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Chapter 1. Seam Tutorial
}
private String getSqlSearchPattern()
{
return searchPattern==null ? "" :
'%' + searchPattern.toLowerCase().replace('*', '%').replace('?', '_') + '%';
}
public String getSearchPattern()
{
return searchPattern;
}
public void setSearchPattern(String searchPattern)
{
this.searchPattern = searchPattern;
}
}
1.9.3. Using "push"-style MVC in a RESTful application
Very occasionally, it makes more sense to use push-style MVC for processing RESTful pages,
and so Seam provides the notion of a page action. The Blog example uses a page action for the
blog entry page, entry.xhtml. Note that this is a little bit contrived, it would have been easier to
use pull-style MVC here as well.
The entryAction component works much like an action class in a traditional push-MVC actionoriented framework like Struts:
@Name("entryAction")
@Scope(STATELESS)
public class EntryAction
{
@In(create=true)
private Blog blog;
@Out
private BlogEntry blogEntry;
public void loadBlogEntry(String id) throws EntryNotFoundException
{
blogEntry = blog.getBlogEntry(id);
if (blogEntry==null) throw new EntryNotFoundException(id);
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Using "push"-style MVC in a RESTful
application
}
}
Page actions are also declared in pages.xml:
<pages>
...
<page view-id="/entry.xhtml" action="#{entryAction.loadBlogEntry(blogEntry.id)}">
<param name="blogEntryId" value="#{blogEntry.id}"/>
</page>
<page view-id="/post.xhtml" action="#{loginAction.challenge}"/>
<page view-id="*" action="#{blog.hitCount.hit}"/>
</pages>
Notice that the example is using page actions for some other functionality—the login challenge,
and the pageview counter. Also notice the use of a parameter in the page action method binding.
This is not a standard feature of JSF EL, but Seam lets you use it, not just for page actions, but
also in JSF method bindings.
When the entry.xhtml page is requested, Seam first binds the page parameter blogEntryId
to the model, then runs the page action, which retrieves the needed data—the blogEntry—and
places it in the Seam event context. Finally, the following is rendered:
<div class="blogEntry">
<h3>#{blogEntry.title}</h3>
<div>
<h:outputText escape="false" value="#{blogEntry.body}"/>
</div>
<p>
[Posted on&#160;
<h:outputText value="#{blogEntry.date}">
<f:convertDateTime timezone="#{blog.timeZone}"
locale="#{blog.locale}" type="both"/>
</h:outputText>]
</p>
</div>
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Chapter 1. Seam Tutorial
If the blog entry is not found in the database, the EntryNotFoundException exception is thrown.
We want this exception to result in a 404 error, not a 505, so we annotate the exception class:
@ApplicationException(rollback=true)
@HttpError(errorCode=HttpServletResponse.SC_NOT_FOUND)
public class EntryNotFoundException extends Exception
{
EntryNotFoundException(String id)
{
super("entry not found: " + id);
}
}
An alternative implementation of the example does not use the parameter in the method binding:
@Name("entryAction")
@Scope(STATELESS)
public class EntryAction
{
@In(create=true)
private Blog blog;
@In @Out
private BlogEntry blogEntry;
public void loadBlogEntry() throws EntryNotFoundException
{
blogEntry = blog.getBlogEntry( blogEntry.getId() );
if (blogEntry==null) throw new EntryNotFoundException(id);
}
}
<pages>
...
<page view-id="/entry.xhtml" action="#{entryAction.loadBlogEntry}">
<param name="blogEntryId" value="#{blogEntry.id}"/>
</page>
...
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Using "push"-style MVC in a RESTful
application
</pages>
It is a matter of taste which implementation you prefer.
61
62
Chapter 2.
Getting started with Seam, using
seam-gen
The Seam distribution includes a command line utility that makes it really easy to set up an Eclipse
project, generate some simple Seam skeleton code, and reverse engineer an application from a
preexisting database.
This is the easy way to get your feet wet with Seam, and gives you some ammunition for next
time you find yourself trapped in an elevator with one of those tedious Ruby guys ranting about
how great and wonderful his new toy is for building totally trivial applications that put things in
databases.
In this release, seam-gen works best for people with JBoss AS. You can use the generated project
with other J2EE or Java EE 5 application servers by making a few manual changes to the project
configuration.
You can use seam-gen without Eclipse, but in this tutorial, we want to show you how to use it in
conjunction with Eclipse for debugging and integration testing. If you don't want to install Eclipse,
you can still follow along with this tutorial—all steps can be performed from the command line.
Seam-gen is basically just a big ugly Ant script wrapped around Hibernate Tools, together with
some templates. That makes it easy to customize if you need to.
2.1. Before you start
Make sure you have JDK 5 or JDK 6, JBoss AS 4.2 and Ant 1.6, along with recent versions of
Eclipse, the JBoss IDE plugin for Eclipse and the TestNG plugin for Eclipse correctly installed
before starting. Add your JBoss installation to the JBoss Server View in Eclipse. Start JBoss in
debug mode. Finally, start a command prompt in the directory where you unzipped the Seam
distribution.
JBoss has sophisticated support for hot re-deployment of WARs and EARs. Unfortunately,
due to bugs in the JVM, repeated redeployment of an EAR—which is common during
development—eventually causes the JVM to run out of perm gen space. For this reason, we
recommend running JBoss in a JVM with a large perm gen space at development time. If you're
running JBoss from JBoss IDE, you can configure this in the server launch configuration, under
"VM arguments". We suggest the following values:
-Xms512m -Xmx1024m -XX:PermSize=256m -XX:MaxPermSize=512
If you don't have so much memory available, the following is our minimum recommendation:
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Chapter 2. Getting started wi...
-Xms256m -Xmx512m -XX:PermSize=128m -XX:MaxPermSize=256
If you're running JBoss from the command line, you can configure the JVM options in bin/
run.conf.
If you don't want to bother with this stuff now, you don't have to—come back to it later, when you
get your first OutOfMemoryException.
2.2. Setting up a new Eclipse project
The first thing we need to do is configure seam-gen for your environment: JBoss AS installation
directory, Eclipse workspace, and database connection. It's easy, just type:
cd jboss-seam-2.0.x
seam setup
And you will be prompted for the needed information:
~/workspace/jboss-seam$ ./seam setup
Buildfile: build.xml
init:
setup:
[echo] Welcome to seam-gen :-)
[input] Enter your Java project workspace (the directory that contains your Seam projects)
[C:/Projects] [C:/Projects]
/Users/pmuir/workspace
[input] Enter your JBoss home directory [C:/Program Files/jboss-4.2.2.GA] [C:/Program Files/
jboss-4.2.2.GA]
/Applications/jboss-4.2.2.GA
[input] Enter the project name [myproject] [myproject]
helloworld
[echo] Accepted project name as: helloworld
[input] Select a RichFaces skin (not applicable if using ICEFaces) [blueSky] ([blueSky], classic,
ruby, wine, deepMarine, emeraldTown, sakura, DEFAULT)
[input] Is this project deployed as an EAR (with EJB components) or a WAR (with no EJB
support) [ear] ([ear], war, )
[input] Enter the Java package name for your session beans [com.mydomain.helloworld]
[com.mydomain.helloworld]
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Setting up a new Eclipse project
org.jboss.helloworld
[input] Enter the Java package name for your entity beans [org.jboss.helloworld]
[org.jboss.helloworld]
[input] Enter the Java package name for your test cases [org.jboss.helloworld.test]
[org.jboss.helloworld.test]
[input] What kind of database are you using? [hsql] ([hsql], mysql, oracle, postgres, mssql,
db2, sybase, enterprisedb, h2)
mysql
[input] Enter the Hibernate dialect for your database [org.hibernate.dialect.MySQLDialect]
[org.hibernate.dialect.MySQLDialect]
[input] Enter the filesystem path to the JDBC driver jar [lib/hsqldb.jar] [lib/hsqldb.jar]
/Users/pmuir/java/mysql.jar
[input] Enter JDBC driver class for your database [com.mysql.jdbc.Driver]
[com.mysql.jdbc.Driver]
[input] Enter the JDBC URL for your database [jdbc:mysql:///test] [jdbc:mysql:///test]
jdbc:mysql:///helloworld
[input] Enter database username [sa] [sa]
pmuir
[input] Enter database password [] []
[input] skipping input as property hibernate.default_schema.new has already been set.
[input] Enter the database catalog name (it is OK to leave this blank) [] []
[input] Are you working with tables that already exist in the database? [n] (y, [n], )
y
[input] Do you want to drop and recreate the database tables and data in import.sql each time
you deploy? [n] (y, [n], )
n
[input] Enter your ICEfaces home directory (leave blank to omit ICEfaces) [] []
[propertyfile] Creating new property file: /Users/pmuir/workspace/jboss-seam/seam-gen/
build.properties
[echo] Installing JDBC driver jar to JBoss server
[echo] Type 'seam create-project' to create the new project
BUILD SUCCESSFUL
Total time: 1 minute 32 seconds
~/workspace/jboss-seam $
The tool provides sensible defaults, which you can accept by just pressing enter at the prompt.
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Chapter 2. Getting started wi...
The most important choice you need to make is between EAR deployment and WAR deployment
of your project. EAR projects support EJB 3.0 and require Java EE 5. WAR projects do not support
EJB 3.0, but may be deployed to a J2EE environment. The packaging of a WAR is also simpler to
understand. If you installed an EJB3-ready application server like JBoss, choose ear. Otherwise,
choose war. We'll assume that you've chosen an EAR deployment for the rest of the tutorial, but
you can follow exactly the same steps for a WAR deployment.
If you are working with an existing data model, make sure you tell seam-gen that the tables already
exist in the database.
The settings are stored in seam-gen/build.properties, but you can also modify them simply
by running seam setup a second time.
Now we can create a new project in our Eclipse workspace directory, by typing:
seam new-project
C:\Projects\jboss-seam>seam new-project
Buildfile: build.xml
...
new-project:
[echo] A new Seam project named 'helloworld' was created in the C:\Projects directory
[echo] Type 'seam explode' and go to http://localhost:8080/helloworld
[echo] Eclipse Users: Add the project into Eclipse using File > New > Project and select General
> Project (not Java Project)
[echo] NetBeans Users: Open the project in NetBeans
BUILD SUCCESSFUL
Total time: 7 seconds
C:\Projects\jboss-seam>
This copies the Seam jars, dependent jars and the JDBC driver jar to a new Eclipse project, and
generates all needed resources and configuration files, a facelets template file and stylesheet,
along with Eclipse metadata and an Ant build script. The Eclipse project will be automatically
deployed to an exploded directory structure in JBoss AS as soon as you add the project using
New -> Project... -> General -> Project -> Next, typing the Project name (helloworld
in this case), and then clicking Finish. Do not select Java Project from the New Project wizard.
If your default JDK in Eclipse is not a Java SE 5 or Java SE 6 JDK, you will need to select a Java
SE 5 compliant JDK using Project -> Properties -> Java Compiler.
Alternatively, you can deploy the project from outside Eclipse by typing seam explode.
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Creating a new action
Go to http://localhost:8080/helloworld to see a welcome page. This is a facelets page,
view/home.xhtml, using the template view/layout/template.xhtml. You can edit this page,
or the template, in eclipse, and see the results immediately, by clicking refresh in your browser.
Don't get scared by the XML configuration documents that were generated into the project
directory. They are mostly standard Java EE stuff, the stuff you need to create once and then
never look at again, and they are 90% the same between all Seam projects. (They are so easy
to write that even seam-gen can do it.)
The generated project includes three database and persistence configurations. The
persistence-test.xml and import-test.sql files are used when running the TestNG unit
tests against HSQLDB. The database schema and the test data in import-test.sql is always
exported to the database before running tests. The myproject-dev-ds.xml, persistencedev.xmland import-dev.sql files are for use when deploying the application to your
development database. The schema might be exported automatically at deployment, depending
upon whether you told seam-gen that you are working with an existing database. The myprojectprod-ds.xml, persistence-prod.xmland import-prod.sql files are for use when deploying the
application to your production database. The schema is not exported automatically at deployment.
2.3. Creating a new action
If you're used to traditional action-style web frameworks, you're probably wondering how you can
create a simple web page with a stateless action method in Java. If you type:
seam new-action
Seam will prompt for some information, and generate a new facelets page and Seam component
for your project.
C:\Projects\jboss-seam>seam new-action
Buildfile: build.xml
validate-workspace:
validate-project:
action-input:
[input] Enter the Seam component name
ping
[input] Enter the local interface name [Ping]
[input] Enter the bean class name [PingBean]
[input] Enter the action method name [ping]
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Chapter 2. Getting started wi...
[input] Enter the page name [ping]
setup-filters:
new-action:
[echo] Creating a new stateless session bean component with an action method
[copy] Copying 1 file to C:\Projects\helloworld\src\action\org\jboss\helloworld
[copy] Copying 1 file to C:\Projects\helloworld\src\action\org\jboss\helloworld
[copy] Copying 1 file to C:\Projects\helloworld\src\action\org\jboss\helloworld\test
[copy] Copying 1 file to C:\Projects\helloworld\src\action\org\jboss\helloworld\test
[copy] Copying 1 file to C:\Projects\helloworld\view
[echo] Type 'seam restart' and go to http://localhost:8080/helloworld/ping.seam
BUILD SUCCESSFUL
Total time: 13 seconds
C:\Projects\jboss-seam>
Because we've added a new Seam component, we need to restart the exploded directory
deployment. You can do this by typing seam restart, or by running the restart target in the
generated project build.xml file from inside Eclipse. Another way to force a restart is to edit
the file resources/META-INF/application.xml in Eclipse. Note that you do not need to restart
JBoss each time you change the application.
Now go to http://localhost:8080/helloworld/ping.seam and click the button. You can see
the code behind this action by looking in the project src directory. Put a breakpoint in the ping()
method, and click the button again.
Finally, locate the PingTest.xml file in the test package and run the integration tests using the
TestNG plugin for Eclipse. Alternatively, run the tests using seam test or the test target of the
generated build.
2.4. Creating a form with an action
The next step is to create a form. Type:
seam new-form
C:\Projects\jboss-seam>seam new-form
Buildfile: C:\Projects\jboss-seam\seam-gen\build.xml
validate-workspace:
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Generating an application from an existing
database
validate-project:
action-input:
[input] Enter the Seam component name
hello
[input] Enter the local interface name [Hello]
[input] Enter the bean class name [HelloBean]
[input] Enter the action method name [hello]
[input] Enter the page name [hello]
setup-filters:
new-form:
[echo] Creating a new stateful session bean component with an action method
[copy] Copying 1 file to C:\Projects\hello\src\com\hello
[copy] Copying 1 file to C:\Projects\hello\src\com\hello
[copy] Copying 1 file to C:\Projects\hello\src\com\hello\test
[copy] Copying 1 file to C:\Projects\hello\view
[copy] Copying 1 file to C:\Projects\hello\src\com\hello\test
[echo] Type 'seam restart' and go to http://localhost:8080/hello/hello.seam
BUILD SUCCESSFUL
Total time: 5 seconds
C:\Projects\jboss-seam>
Restart the application again, and go to http://localhost:8080/helloworld/hello.seam.
Then take a look at the generated code. Run the test. Try adding some new fields to the form and
Seam component (remember to restart the deployment each time you change the Java code).
2.5. Generating an application from an existing
database
Manually create some tables in your database. (If you need to switch to a different database, just
run seam setup again.) Now type:
seam generate-entities
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Chapter 2. Getting started wi...
Restart the deployment, and go to http://localhost:8080/helloworld. You can browse the
database, edit existing objects, and create new objects. If you look at the generated code, you'll
probably be amazed how simple it is! Seam was designed so that data access code is easy to
write by hand, even for people who don't want to cheat by using seam-gen.
2.6. Generating an application from existing JPA/EJB3
entities
Place your existing, valid entity classes inside the src/model. Now type
seam generate-ui
Restart the deployment, and go to http://localhost:8080/helloworld.
2.7. Deploying the application as an EAR
Finally, we want to be able to deploy the application using standard Java EE 5 packaging. First,
we need to remove the exploded directory by running seam unexplode. To deploy the EAR, we
can type seam deploy at the command prompt, or run the deploy target of the generated project
build script. You can undeploy using seam undeploy or the undeploy target.
By default, the application will be deployed with the dev profile. The EAR will include the
persistence-dev.xml and import-dev.sql files, and the myproject-dev-ds.xml file will be
deployed. You can change the profile, and use the prod profile, by typing
seam -Dprofile=prod deploy
You can even define new deployment profiles for your application. Just add appropriately
named files to your project—for example, persistence-staging.xml, import-staging.sql and
myproject-staging-ds.xml—and select the name of the profile using -Dprofile=staging.
2.8. Seam and incremental hot deployment
When you deploy your Seam application as an exploded directory, you'll get some support for
incremental hot deployment at development time. You need to enable debug mode in both Seam
and Facelets, by adding this line to components.xml:
<core:init debug="true">
Now, the following files may be redeployed without requiring a full restart of the web application:
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Using Seam with JBoss 4.0
• any facelets page
• any pages.xml file
But if we want to change any Java code, we still need to do a full restart of the application. (In JBoss
this may be accomplished by touching the top level deployment descriptor: application.xml for
an EAR deployment, or web.xml for a WAR deployment.)
But if you really want a fast edit/compile/test cycle, Seam supports incremental redeployment
of JavaBean components. To make use of this functionality, you must deploy the JavaBean
components into the WEB-INF/dev directory, so that they will be loaded by a special Seam
classloader, instead of by the WAR or EAR classloader.
You need to be aware of the following limitations:
• the components must be JavaBean components, they cannot be EJB3 beans (we are working
on fixing this limitation)
• entities can never be hot-deloyed
• components deployed via components.xml may not be hot-deployed
• the hot-deployable components will not be visible to any classes deployed outside of WEB-INF/
dev
• Seam debug mode must be enabled and jboss-seam-debug.jar must be in WEB-INF/lib
• You must have the Seam filter installed in web.xml
• You may see errors if the system is placed under any load and debug is enabled.
If you create a WAR project using seam-gen, incremental hot deployment is available out of
the box for classes in the src/action source directory. However, seam-gen does not support
incremental hot deployment for EAR projects.
2.9. Using Seam with JBoss 4.0
Seam 2.0 was developed for JavaServer Faces 1.2. When using JBoss AS, we recommend using
JBoss 4.2, which bundles the JSF 1.2 reference implementation. However, it is still possible to use
Seam 2.0 on the JBoss 4.0 platform. There are two basic steps required to do this: install an EJB3enabled version of JBoss 4.0 and replace MyFaces with the JSF 1.2 reference implementation.
Once you complete these steps, Seam 2.0 applications can be deployed to JBoss 4.0.
2.9.1. Install JBoss 4.0
JBoss 4.0 does not ship a default configuration compatible with Seam. To run Seam, you must
install JBoss 4.0.5 using the JEMS 1.2 installer with the ejb3 profile selected. Seam will not run
with an installation that doesn't include EJB3 support. The JEMS installer can be downloaded
from http://labs.jboss.com/jemsinstaller/downloads.
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Chapter 2. Getting started wi...
2.9.2. Install the JSF 1.2 RI
The web configuration for JBoss 4.0 can be found in the server/default/deploy/jbosswebtomcat55.sar. You'll need to delete myfaces-api.jar any myfaces-impl.jar from the jsflibs directory. Then, you'll need to copy jsf-api.jar, jsf-impl.jar, el-api.jar, and elri.jar to that directory. The JSF JARs can be found in the Seam lib directory. The el JARs can
be obtained from the Seam 1.2 release.
You'll also need to edit the conf/web.xml, replacing myfaces-impl.jar with jsf-impl.jar.
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Chapter 3.
Getting started with Seam, using
JBoss Tools
JBoss Tools is a collection of Eclipse plugins. JBoss Tools a project creation wizard for Seam,
Content Assist for the Unified Expression Language (EL) in both facelets and Java code, a
graphical editor for jPDL, a graphical editor for Seam configuration files, support for running Seam
integration tests from within Eclipse, and much more.
In short, if you are an Eclipse user, then you'll want JBoss Tools!
JBoss Tools, as with seam-gen, works best with JBoss AS, but it's possible with a few tweaks to
get your app running on other application servers. The changes are much like those described
for seam-gen later in this reference manual.
3.1. Before you start
Make sure you have JDK 5, JBoss AS 4.2, Eclipse 3.3, the JBoss Tools plugins (at least Seam
Tools, the Visual Page Editor, jBPM Tools and JBoss AS Tools) and the TestNG plugin for Eclipse
correctly installed before starting.
TODO - detail where the update sites are.
3.2. Setting up a new Seam project
Start up Eclipse and select the Seam perspective.
Go to File -> New -> Seam Web Project.
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Chapter 3. Getting started wi...
First, enter a name for your new project. For this tutorial, we're going to use helloworld .
Now, we need to tell JBoss Tools about JBoss AS. This is a two stage process, first we need to
define a runtime, make sure you select JBoss AS 4.2:
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Setting up a new Seam project
Enter a name for the runtime, and locate it on your hard drive:
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Chapter 3. Getting started wi...
Next, we need to define a server JBoss Tools can deploy the project to. Make sure to again select
JBoss AS 4.2, and also the runtime you just defined:
76
Setting up a new Seam project
On the next screen give the server a name, and hit Finish:
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Chapter 3. Getting started wi...
Make sure the runtime and server you just created are selected, select Dynamic Web Project with
Seam 2.0 (technology preview) and hit Next:
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Setting up a new Seam project
The next 3 screens allow you to further customize your new project, but for us the defaults are
fine. So just hit
<empahsis>Next</empahsis>
until you reach the final screen.
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The first step here is to tell JBoss Tools about the Seam download you want to use. Add a new
Seam Runtime - make sure to give it a name, and select 2.0 as the version:
The most important choice you need to make is between EAR deployment and WAR deployment
of your project. EAR projects support EJB 3.0 and require Java EE 5. WAR projects do not support
EJB 3.0, but may be deployed to a J2EE environment. The packaging of a WAR is also simpler to
understand. If you installed an EJB3-ready application server like JBoss, choose EAR. Otherwise,
choose WAR. We'll assume that you've chosen a WAR deployment for the rest of the tutorial, but
you can follow exactly the same steps for a EAR deployment.
Next, select your database type. We'll assume you have MySQL installed, with an existing
schema. You'll need to tell JBoss Tools about the database, select MySQL as the database, and
create a new connection profile. Select Generic JDBC Connection:
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Setting up a new Seam project
Give it a name:
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Setting up a new Seam project
JBoss Tools doesn't come with drivers for any databases, so you need to tell JBoss Tools where
the MySQL JDBC driver is. Tell it about the driver by clicking ....
Locate MySQL 5, and hit Add...:
Choose the MySQL JDBC Driver template:
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Locate the jar on your computer by choosing Edit Jar/Zip:
Review the username and password used to connect, and if correct, hit Ok.
Finally, choose the newly created driver:
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Setting up a new Seam project
If you are working with an existing data model, make sure you tell JBoss Tools that the tables
already exist in the database.
Review the username and password used to connect, test the connection using the Test
Connection button, and if it works, hit Finish:
Finally, review the package names for your generated beans, and if you are happy, click Finish:
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JBoss has sophisticated support for hot re-deployment of WARs and EARs. Unfortunately,
due to bugs in the JVM, repeated redeployment of an EAR—which is common during
development—eventually causes the JVM to run out of perm gen space. For this reason, we
recommend running JBoss in a JVM with a large perm gen space at development time. We
suggest the following values:
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Setting up a new Seam project
-Xms512m -Xmx1024m -XX:PermSize=256m -XX:MaxPermSize=512
If you don't have so much memory available, the following is our minimum recommendation:
-Xms256m -Xmx512m -XX:PermSize=128m -XX:MaxPermSize=256
Locate the server in the JBoss Server View, right click on the server and select Edit Launch
Configuration:
Then, alter the VM arguements:
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Chapter 3. Getting started wi...
If you don't want to bother with this stuff now, you don't have to—come back to it later, when you
get your first OutOfMemoryException.
To start JBoss, and deploy the project, just right click on the server you created, and click Start,
(or Debug to start in debug mode):
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Creating a new action
Don't get scared by the XML configuration documents that were generated into the project
directory. They are mostly standard Java EE stuff, the stuff you need to create once and then
never look at again, and they are 90% the same between all Seam projects.
3.3. Creating a new action
If you're used to traditional action-style web frameworks, you're probably wondering how you can
create a simple web page with a stateless action method in Java.
First, select New -> Seam Action:
Now, enter the name of the Seam component. JBoss Tools selects sensible defaults for other
fields:
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Finally, hit Finish.
Now go to http://localhost:8080/helloworld/ping.seam and click the button. You can see
the code behind this action by looking in the project src directory. Put a breakpoint in the ping()
method, and click the button again.
Finally, open the helloworld-test project, locate PingTest class, right click on it, and choose
Run As -> TestNG Test:
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Creating a form with an action
3.4. Creating a form with an action
The first step is to create a form. Select New -> Seam Form:
Now, enter the name of the Seam component. JBoss Tools selects sensible defaults for other
fields:
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Go to http://localhost:8080/helloworld/hello.seam. Then take a look at the generated
code. Run the test. Try adding some new fields to the form and Seam component (note, you don't
need to restart the app server each time you change the code in src/action as Seam hot reloads
the component for you Section 3.6, “Seam and incremental hot deployment with JBoss Tools”).
3.5. Generating an application from an existing
database
Manually create some tables in your database. (If you need to switch to a different database, create
a new project, and select the correct database). Then, select New -> Seam Generate Entities:
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Generating an application from an existing
database
JBoss Tools gives you the option to either reverse engineer entities, components and views from a
database schema or to reverse engineer components and views from existing JPA entities. We're
going to do Reverse engieneer from database.
Restart the deployment:
Then go to http://localhost:8080/helloworld. You can browse the database, edit existing
objects, and create new objects. If you look at the generated code, you'll probably be amazed
how simple it is! Seam was designed so that data access code is easy to write by hand, even for
people who don't want to cheat by using reverse engineering.
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3.6. Seam and incremental hot deployment with JBoss
Tools
JBoss Tools supports incremental hot deployment of:
• any facelets page
• any pages.xml file
out of the box.
But if we want to change any Java code, we still need to do a full restart of the application by
doing a Full Publish.
But if you really want a fast edit/compile/test cycle, Seam supports incremental redeployment
of JavaBean components. To make use of this functionality, you must deploy the JavaBean
components into the WEB-INF/dev directory, so that they will be loaded by a special Seam
classloader, instead of by the WAR or EAR classloader.
You need to be aware of the following limitations:
• the components must be JavaBean components, they cannot be EJB3 beans (we are working
on fixing this limitation)
• entities can never be hot-deloyed
• components deployed via components.xml may not be hot-deployed
• the hot-deployable components will not be visible to any classes deployed outside of WEB-INF/
dev
• Seam debug mode must be enabled and jboss-seam-debug.jar must be in WEB-INF/lib
• You must have the Seam filter installed in web.xml
• You may see errors if the system is placed under any load and debug is enabled.
If you create a WAR project using JBoss Tools, incremental hot deployment is available out of
the box for classes in the src/action source directory. However, JBoss Tools does not support
incremental hot deployment for EAR projects.
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Chapter 4.
The contextual component model
The two core concepts in Seam are the notion of a context and the notion of a component.
Components are stateful objects, usually EJBs, and an instance of a component is associated
with a context, and given a name in that context. Bijection provides a mechanism for aliasing
internal component names (instance variables) to contextual names, allowing component trees to
be dynamically assembled, and reassembled by Seam.
Let's start by describing the contexts built in to Seam.
4.1. Seam contexts
Seam contexts are created and destroyed by the framework. The application does not control
context demarcation via explicit Java API calls. Context are usually implicit. In some cases,
however, contexts are demarcated via annotations.
The basic Seam contexts are:
• Stateless context
• Event (or request) context
• Page context
• Conversation context
• Session context
• Business process context
• Application context
You will recognize some of these contexts from servlet and related specifications. However, two of
them might be new to you: conversation context, and business process context. One reason state
management in web applications is so fragile and error-prone is that the three built-in contexts
(request, session and application) are not especially meaningful from the point of view of the
business logic. A user login session, for example, is a fairly arbitrary construct in terms of the
actual application work flow. Therefore, most Seam components are scoped to the conversation
or business process contexts, since they are the contexts which are most meaningful in terms
of the application.
Let's look at each context in turn.
4.1.1. Stateless context
Components which are truly stateless (stateless session beans, primarily) always live in the
stateless context (this is really a non-context). Stateless components are not very interesting, and
are arguably not very object-oriented. Nevertheless, they are important and often useful.
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4.1.2. Event context
The event context is the "narrowest" stateful context, and is a generalization of the notion of the
web request context to cover other kinds of events. Nevertheless, the event context associated
with the lifecycle of a JSF request is the most important example of an event context, and the
one you will work with most often. Components associated with the event context are destroyed
at the end of the request, but their state is available and well-defined for at least the lifecycle of
the request.
When you invoke a Seam component via RMI, or Seam Remoting, the event context is created
and destroyed just for the invocation.
4.1.3. Page context
The page context allows you to associate state with a particular instance of a rendered page.
You can initialize state in your event listener, or while actually rendering the page, and then have
access to it from any event that originates from that page. This is especially useful for functionality
like clickable lists, where the list is backed by changing data on the server side. The state is
actually serialized to the client, so this construct is extremely robust with respect to multi-window
operation and the back button.
4.1.4. Conversation context
The conversation context is a truly central concept in Seam. A conversation is a unit of work from
the point of view of the user. It might span several interactions with the user, several requests,
and several database transactions. But to the user, a conversation solves a single problem. For
example, "book hotel", "approve contract", "create order" are all conversations. You might like to
think of a conversation implementing a single "use case" or "user story", but the relationship is
not necessarily quite exact.
A conversation holds state associated with "what the user is doing now, in this window". A single
user may have multiple conversations in progress at any point in time, usually in multiple windows.
The conversation context allows us to ensure that state from the different conversations does not
collide and cause bugs.
It might take you some time to get used to thinking of applications in terms of conversations. But
once you get used to it, we think you'll love the notion, and never be able to not think in terms
of conversations again!
Some conversations last for just a single request. Conversations that span multiple requests must
be demarcated using annotations provided by Seam.
Some conversations are also tasks. A task is a conversation that is significant in terms of a longrunning business process, and has the potential to trigger a business process state transition when
it is successfully completed. Seam provides a special set of annotations for task demarcation.
Conversations may be nested, with one conversation taking place "inside" a wider conversation.
This is an advanced feature.
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Session context
Usually, conversation state is actually held by Seam in the servlet session between
requests. Seam implements configurable conversation timeout, automatically destroying inactive
conversations, and thus ensuring that the state held by a single user login session does not grow
without bound if the user abandons conversations.
Seam serializes processing of concurrent requests that take place in the same long-running
conversation context, in the same process.
Alternatively, Seam may be configured to keep conversational state in the client browser.
4.1.5. Session context
A session context holds state associated with the user login session. While there are some cases
where it is useful to share state between several conversations, we generally frown on the use of
session context for holding components other than global information about the logged in user.
In a JSR-168 portal environment, the session context represents the portlet session.
4.1.6. Business process context
The business process context holds state associated with the long running business process. This
state is managed and made persistent by the BPM engine (JBoss jBPM). The business process
spans multiple interactions with multiple users, so this state is shared between multiple users, but
in a well-defined manner. The current task determines the current business process instance, and
the lifecycle of the business process is defined externally using a process definition language, so
there are no special annotations for business process demarcation.
4.1.7. Application context
The application context is the familiar servlet context from the servlet spec. Application context
is mainly useful for holding static information such as configuration data, reference data or
metamodels. For example, Seam stores its own configuration and metamodel in the application
context.
4.1.8. Context variables
A context defines a namespace, a set of context variables. These work much the same as session
or request attributes in the servlet spec. You may bind any value you like to a context variable,
but usually we bind Seam component instances to context variables.
So, within a context, a component instance is identified by the context variable name (this is
usually, but not always, the same as the component name). You may programatically access a
named component instance in a particular scope via the Contexts class, which provides access
to several thread-bound instances of the Context interface:
User user = (User) Contexts.getSessionContext().get("user");
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You may also set or change the value associated with a name:
Contexts.getSessionContext().set("user", user);
Usually, however, we obtain components from a context via injection, and put component
instances into a context via outjection.
4.1.9. Context search priority
Sometimes, as above, component instances are obtained from a particular known scope. Other
times, all stateful scopes are searched, in priority order. The order is as follows:
• Event context
• Page context
• Conversation context
• Session context
• Business process context
• Application context
You can perform a priority search by calling Contexts.lookupInStatefulContexts().
Whenever you access a component by name from a JSF page, a priority search occurs.
4.1.10. Concurrency model
Neither the servlet nor EJB specifications define any facilities for managing concurrent requests
originating from the same client. The servlet container simply lets all threads run concurrently
and leaves enforcing threadsafeness to application code. The EJB container allows stateless
components to be accessed concurrently, and throws an exception if multiple threads access a
stateful session bean.
This behavior might have been okay in old-style web applications which were based around finegrained, synchronous requests. But for modern applications which make heavy use of many finegrained, asynchronous (AJAX) requests, concurrency is a fact of life, and must be supported by
the programming model. Seam weaves a concurrency management layer into its context model.
The Seam session and application contexts are multithreaded. Seam will allow concurrent
requests in a context to be processed concurrently. The event and page contexts are by nature
single threaded. The business process context is strictly speaking multi-threaded, but in practice
concurrency is sufficiently rare that this fact may be disregarded most of the time. Finally, Seam
enforces a single thread per conversation per process model for the conversation context by
serializing concurrent requests in the same long-running conversation context.
Since the session context is multithreaded, and often contains volatile state, session scope
components are always protected by Seam from concurrent access. Seam serializes requests to
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Seam components
session scope session beans and JavaBeans by default (and detects and breaks any deadlocks
that occur). This is not the default behaviour for application scoped components however, since
application scoped components do not usually hold volatile state and because synchronization at
the global level is extremely expensive. However, you can force a serialized threading model on
any session bean or JavaBean component by adding the @Synchronized annotation.
This concurrency model means that AJAX clients can safely use volatile session and
conversational state, without the need for any special work on the part of the developer.
4.2. Seam components
Seam components are POJOs (Plain Old Java Objects). In particular, they are JavaBeans or
EJB 3.0 enterprise beans. While Seam does not require that components be EJBs and can even
be used without an EJB 3.0 compliant container, Seam was designed with EJB 3.0 in mind and
includes deep integration with EJB 3.0. Seam supports the following component types.
• EJB 3.0 stateless session beans
• EJB 3.0 stateful session beans
• EJB 3.0 entity beans
• JavaBeans
• EJB 3.0 message-driven beans
4.2.1. Stateless session beans
Stateless session bean components are not able to hold state across multiple invocations.
Therefore, they usually work by operating upon the state of other components in the various
Seam contexts. They may be used as JSF action listeners, but cannot provide properties to JSF
components for display.
Stateless session beans always live in the stateless context.
Stateless session beans can be accessed concurrently as a new instance is used for each
request. Assigning the instance to the request is the responsibility of the EJB3 container (normally
instances will be allocated from a reusable pool meaning that you may find any instance variables
contain data from previous uses of the bean).
Stateless session beans are the least interesting kind of Seam component.
Seam stateless session bean components may be instantiated using Component.getInstance()
or @In(create=true). They should not be directly instantiated via JNDI lookup or the new
operator.
4.2.2. Stateful session beans
Stateful session bean components are able to hold state not only across multiple invocations of
the bean, but also across multiple requests. Application state that does not belong in the database
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should usually be held by stateful session beans. This is a major difference between Seam
and many other web application frameworks. Instead of sticking information about the current
conversation directly in the HttpSession, you should keep it in instance variables of a stateful
session bean that is bound to the conversation context. This allows Seam to manage the lifecycle
of this state for you, and ensure that there are no collisions between state relating to different
concurrent conversations.
Stateful session beans are often used as JSF action listener, and as backing beans that provide
properties to JSF components for display or form submission.
By default, stateful session beans are bound to the conversation context. They may never be
bound to the page or stateless contexts.
Concurrent requests to session-scoped stateful session beans are always serialized by Seam.
Seam stateful session bean components may be instantiated using Component.getInstance()
or @In(create=true). They should not be directly instantiated via JNDI lookup or the new
operator.
4.2.3. Entity beans
Entity beans may be bound to a context variable and function as a seam component. Because
entities have a persistent identity in addition to their contextual identity, entity instances are usually
bound explicitly in Java code, rather than being instantiated implicitly by Seam.
Entity bean components do not support bijection or context demarcation. Nor does invocation of
an entity bean trigger validation.
Entity beans are not usually used as JSF action listeners, but do often function as backing beans
that provide properties to JSF components for display or form submission. In particular, it is
common to use an entity as a backing bean, together with a stateless session bean action listener
to implement create/update/delete type functionality.
By default, entity beans are bound to the conversation context. They may never be bound to the
stateless context.
Note that it in a clustered environment is somewhat less efficient to bind an entity bean directly to
a conversation or session scoped Seam context variable than it would be to hold a reference to
the entity bean in a stateful session bean. For this reason, not all Seam applications define entity
beans to be Seam components.
Seam entity bean components may be instantiated using Component.getInstance(),
@In(create=true) or directly using the new operator.
4.2.4. JavaBeans
Javabeans may be used just like a stateless or stateful session bean. However, they do not provide
the functionality of a session bean (declarative transaction demarcation, declarative security,
efficient clustered state replication, EJB 3.0 persistence, timeout methods, etc).
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Message-driven beans
In a later chapter, we show you how to use Seam and Hibernate without an EJB container. In
this use case, components are JavaBeans instead of session beans. Note, however, that in many
application servers it is somewhat less efficient to cluster conversation or session scoped Seam
JavaBean components than it is to cluster stateful session bean components.
By default, JavaBeans are bound to the event context.
Concurrent requests to session-scoped JavaBeans are always serialized by Seam.
Seam JavaBean components may be instantiated using Component.getInstance() or
@In(create=true). They should not be directly instantiated using the new operator.
4.2.5. Message-driven beans
Message-driven beans may function as a seam component. However, message-driven beans
are called quite differently to other Seam components - instead of invoking them via the context
variable, they listen for messages sent to a JMS queue or topic.
Message-driven beans may not be bound to a Seam context. Nor do they have access to the
session or conversation state of their "caller". However, they do support bijection and some other
Seam functionality.
Message-driven beans are never instantiated by the application. They are instantiated by the EJB
container when a message is received.
4.2.6. Interception
In order to perform its magic (bijection, context demarcation, validation, etc), Seam must intercept
component invocations. For JavaBeans, Seam is in full control of instantiation of the component,
and no special configuration is needed. For entity beans, interception is not required since bijection
and context demarcation are not defined. For session beans, we must register an EJB interceptor
for the session bean component. We could use an annotation, as follows:
@Stateless
@Interceptors(SeamInterceptor.class)
public class LoginAction implements Login {
...
}
But a much better way is to define the interceptor in ejb-jar.xml.
<interceptors>
<interceptor>
<interceptor-class>org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
</interceptor>
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</interceptors>
<assembly-descriptor>
<interceptor-binding>
<ejb-name>*</ejb-name>
<interceptor-class>org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
</interceptor-binding>
</assembly-descriptor>
4.2.7. Component names
All seam components need a name. We can assign a name to a component using the @Name
annotation:
@Name("loginAction")
@Stateless
public class LoginAction implements Login {
...
}
This name is the seam component name and is not related to any other name defined by the EJB
specification. However, seam component names work just like JSF managed bean names and
you can think of the two concepts as identical.
@Name is not the only way to define a component name, but we always need to specify the name
somewhere. If we don't, then none of the other Seam annotations will function.
Just like in JSF, a seam component instance is usually bound to a context variable with the
same name as the component name. So, for example, we would access the LoginAction using
Contexts.getStatelessContext().get("loginAction"). In particular, whenever Seam itself
instantiates a component, it binds the new instance to a variable with the component name.
However, again like JSF, it is possible for the application to bind a component to some other
context variable by programmatic API call. This is only useful if a particular component serves
more than one role in the system. For example, the currently logged in User might be bound to
the currentUser session context variable, while a User that is the subject of some administration
functionality might be bound to the user conversation context variable.
For very large applications, and for built-in seam components, qualified names are often used.
@Name("com.jboss.myapp.loginAction")
@Stateless
public class LoginAction implements Login {
...
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Defining the component scope
}
We may use the qualified component name both in Java code and in JSF's expression language:
<h:commandButton type="submit" value="Login"
action="#{com.jboss.myapp.loginAction.login}"/>
Since this is noisy, Seam also provides a means of aliasing a qualified name to a simple name.
Add a line like this to the components.xml file:
<factory name="loginAction" scope="STATELESS" value="#{com.jboss.myapp.loginAction}"/>
All of the built-in Seam components have qualified names, but most of them are aliased to a simple
name by the components.xml file included in the Seam jar.
4.2.8. Defining the component scope
We can override the default scope (context) of a component using the @Scope annotation. This
lets us define what context a component instance is bound to, when it is instantiated by Seam.
@Name("user")
@Entity
@Scope(SESSION)
public class User {
...
}
org.jboss.seam.ScopeType defines an enumeration of possible scopes.
4.2.9. Components with multiple roles
Some Seam component classes can fulfill more than one role in the system. For example, we often
have a User class which is usually used as a session-scoped component representing the current
user but is used in user administration screens as a conversation-scoped component. The @Role
annotation lets us define an additional named role for a component, with a different scope—it lets
us bind the same component class to different context variables. (Any Seam component instance
may be bound to multiple context variables, but this lets us do it at the class level, and take
advantage of auto-instantiation.)
@Name("user")
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@Entity
@Scope(CONVERSATION)
@Role(name="currentUser", scope=SESSION)
public class User {
...
}
The @Roles annotation lets us specify as many additional roles as we like.
@Name("user")
@Entity
@Scope(CONVERSATION)
@Roles({@Role(name="currentUser", scope=SESSION),
@Role(name="tempUser", scope=EVENT)})
public class User {
...
}
4.2.10. Built-in components
Like many good frameworks, Seam eats its own dogfood and is implemented mostly as a set of
built-in Seam interceptors (see later) and Seam components. This makes it easy for applications
to interact with built-in components at runtime or even customize the basic functionality of Seam
by replacing the built-in components with custom implementations. The built-in components are
defined in the Seam namespace org.jboss.seam.core and the Java package of the same name.
The built-in components may be injected, just like any Seam components, but they also provide
convenient static instance() methods:
FacesMessages.instance().add("Welcome back, #{user.name}!");
4.3. Bijection
Dependency injection or inversion of control is by now a familiar concept to most Java developers.
Dependency injection allows a component to obtain a reference to another component by
having the container "inject" the other component to a setter method or instance variable. In all
dependency injection implementations that we have seen, injection occurs when the component
is constructed, and the reference does not subsequently change for the lifetime of the component
instance. For stateless components, this is reasonable. From the point of view of a client, all
instances of a particular stateless component are interchangeable. On the other hand, Seam
emphasizes the use of stateful components. So traditional dependency injection is no longer a
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Bijection
very useful construct. Seam introduces the notion of bijection as a generalization of injection. In
contrast to injection, bijection is:
• contextual - bijection is used to assemble stateful components from various different contexts (a
component from a "wider" context may even have a reference to a component from a "narrower"
context)
• bidirectional - values are injected from context variables into attributes of the component being
invoked, and also outjected from the component attributes back out to the context, allowing the
component being invoked to manipulate the values of contextual variables simply by setting its
own instance variables
• dynamic - since the value of contextual variables changes over time, and since Seam
components are stateful, bijection takes place every time a component is invoked
In essence, bijection lets you alias a context variable to a component instance variable, by
specifying that the value of the instance variable is injected, outjected, or both. Of course, we use
annotations to enable bijection.
The @In annotation specifies that a value should be injected, either into an instance variable:
@Name("loginAction")
@Stateless
public class LoginAction implements Login {
@In User user;
...
}
or into a setter method:
@Name("loginAction")
@Stateless
public class LoginAction implements Login {
User user;
@In
public void setUser(User user) {
this.user=user;
}
...
}
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By default, Seam will do a priority search of all contexts, using the name of the property or instance
variable that is being injected. You may wish to specify the context variable name explicitly, using,
for example, @In("currentUser").
If you want Seam to create an instance of the component when there is no existing component
instance bound to the named context variable, you should specify @In(create=true). If the value
is optional (it can be null), specify @In(required=false).
For some components, it can be repetitive to have to specify @In(create=true) everywhere they
are used. In such cases, you can annotate the component @AutoCreate, and then it will always
be created, whenever needed, even without the explicit use of create=true.
You can even inject the value of an expression:
@Name("loginAction")
@Stateless
public class LoginAction implements Login {
@In("#{user.username}") String username;
...
}
Injected values are disinjected (i.e, set to null) immediately after method completion and
outjection.
(There is much more information about component lifecycle and injection in the next chapter.)
The @Out annotation specifies that an attribute should be outjected, either from an instance
variable:
@Name("loginAction")
@Stateless
public class LoginAction implements Login {
@Out User user;
...
}
or from a getter method:
@Name("loginAction")
@Stateless
public class LoginAction implements Login {
User user;
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Lifecycle methods
@Out
public User getUser() {
return user;
}
...
}
An attribute may be both injected and outjected:
@Name("loginAction")
@Stateless
public class LoginAction implements Login {
@In @Out User user;
...
}
or:
@Name("loginAction")
@Stateless
public class LoginAction implements Login {
User user;
@In
public void setUser(User user) {
this.user=user;
}
@Out
public User getUser() {
return user;
}
...
}
4.4. Lifecycle methods
Session bean and entity bean Seam components support all the usual EJB 3.0 lifecycle
callback (@PostConstruct, @PreDestroy, etc). But Seam also supports the use of any of these
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callbacks with JavaBean components. However, since these annotations are not available in
a J2EE environment, Seam defines two additional component lifecycle callbacks, equivalent to
@PostConstruct and @PreDestroy.
The @Create method is called after Seam instantiates a component. Components may define only
one @Create method.
The @Destroy method is called when the context that the Seam component is bound to ends.
Components may define only one @Destroy method.
In addition, stateful session bean components must define a method with no parameters annotated
@Remove. This method is called by Seam when the context ends.
Finally, a related annotation is the @Startup annotation, which may be applied to any application
or session scoped component. The @Startup annotation tells Seam to instantiate the component
immediately, when the context begins, instead of waiting until it is first referenced by a
client. It is possible to control the order of instantiation of startup components by specifying
@Startup(depends={....}).
4.5. Conditional installation
The @Install annotation lets you control conditional installation of components that are required
in some deployment scenarios and not in others. This is useful if:
• You want to mock out some infrastructural component in tests.
• You want change the implementation of a component in certain deployment scenarios.
• You want to install some components only if their dependencies are available (useful for
framework authors).
@Install works by letting you specify precedence and dependencies.
The precedence of a component is a number that Seam uses to decide which component to
install when there are multiple classes with the same component name in the classpath. Seam
will choose the component with the higher precendence. There are some predefined precedence
values (in ascending order):
1. BUILT_IN — the lowest precedece components are the components built in to Seam.
2. FRAMEWORK — components defined by third-party frameworks may override built-in
components, but are overridden by application components.
3. APPLICATION — the default precedence. This is appropriate for most application components.
4. DEPLOYMENT — for application components which are deployment-specific.
5. MOCK — for mock objects used in testing.
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Logging
Suppose we have a component named messageSender that talks to a JMS queue.
@Name("messageSender")
public class MessageSender {
public void sendMessage() {
//do something with JMS
}
}
In our unit tests, we don't have a JMS queue available, so we would like to stub out this method.
We'll create a mock component that exists in the classpath when unit tests are running, but is
never deployed with the application:
@Name("messageSender")
@Install(precedence=MOCK)
public class MockMessageSender extends MessageSender {
public void sendMessage() {
//do nothing!
}
}
The precedence helps Seam decide which version to use when it finds both components in the
classpath.
This is nice if we are able to control exactly which classes are in the classpath. But if I'm writing
a reusable framework with many dependecies, I don't want to have to break that framework
across many jars. I want to be able to decide which components to install depending upon
what other components are installed, and upon what classes are available in the classpath. The
@Install annotation also controls this functionality. Seam uses this mechanism internally to
enable conditional installation of many of the built-in components. However, you probably won't
need to use it in your application.
4.6. Logging
Who is not totally fed up with seeing noisy code like this?
private static final Log log = LogFactory.getLog(CreateOrderAction.class);
public Order createOrder(User user, Product product, int quantity) {
if ( log.isDebugEnabled() ) {
log.debug("Creating new order for user: " + user.username() +
" product: " + product.name()
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+ " quantity: " + quantity);
}
return new Order(user, product, quantity);
}
It is difficult to imagine how the code for a simple log message could possibly be more verbose.
There is more lines of code tied up in logging than in the actual business logic! I remain totally
astonished that the Java community has not come up with anything better in 10 years.
Seam provides a logging API that simplifies this code significantly:
@Logger private Log log;
public Order createOrder(User user, Product product, int quantity) {
log.debug("Creating new order for user: #0 product: #1 quantity: #2", user.username(),
product.name(), quantity);
return new Order(user, product, quantity);
}
It doesn't matter if you declare the log variable static or not—it will work either way, except for
entity bean components which require the log variable to be static.
Note that we don't need the noisy if ( log.isDebugEnabled() ) guard, since string
concatenation happens inside the debug() method. Note also that we don't usually need to specify
the log category explicitly, since Seam knows what component it is injecting the Log into.
If User and Product are Seam components available in the current contexts, it gets even better:
@Logger private Log log;
public Order createOrder(User user, Product product, int quantity) {
log.debug("Creating new order for user: #{user.username} product: #{product.name} quantity:
#0", quantity);
return new Order(user, product, quantity);
}
Seam logging automagically chooses whether to send output to log4j or JDK logging. If log4j is in
the classpath, Seam with use it. If it is not, Seam will use JDK logging.
4.7. The Mutable interface and @ReadOnly
Many application servers feature an amazingly broken implementation of HttpSession clustering,
where changes to the state of mutable objects bound to the session are only replicated when the
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The Mutable interface and @ReadOnly
application calls setAttribute() explicitly. This is a source of bugs that can not effectively be
tested for at development time, since they will only manifest when failover occurs. Furthermore,
the actual replication message contains the entire serialized object graph bound to the session
attribute, which is inefficient.
Of course, EJB stateful session beans must perform automatic dirty checking and replication of
mutable state and a sophisticated EJB container can introduce optimizations such as attributelevel replication. Unfortunately, not all Seam users have the good fortune to be working in an
environment that supports EJB 3.0. So, for session and conversation scoped JavaBean and entity
bean components, Seam provides an extra layer of cluster-safe state management over the top
of the web container session clustering.
For session or conversation scoped JavaBean components, Seam automatically forces replication
to occur by calling setAttribute() once in every request that the component was invoked by
the application. Of course, this strategy is inefficient for read-mostly components. You can control
this behavior by implementing the org.jboss.seam.core.Mutable interface, or by extending
org.jboss.seam.core.AbstractMutable, and writing your own dirty-checking logic inside the
component. For example,
@Name("account")
public class Account extends AbstractMutable
{
private BigDecimal balance;
public void setBalance(BigDecimal balance)
{
setDirty(this.balance, balance);
this.balance = balance;
}
public BigDecimal getBalance()
{
return balance;
}
...
}
Or, you can use the @ReadOnly annotation to achieve a similar effect:
@Name("account")
public class Account
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{
private BigDecimal balance;
public void setBalance(BigDecimal balance)
{
this.balance = balance;
}
@ReadOnly
public BigDecimal getBalance()
{
return balance;
}
...
}
For session or conversation scoped entity bean components, Seam automatically forces
replication to occur by calling setAttribute() once in every request, unless the (conversationscoped) entity is currently associated with a Seam-managed persistence context, in which case no
replication is needed. This strategy is not necessarily efficient, so session or conversation scope
entity beans should be used with care. You can always write a stateful session bean or JavaBean
component to "manage" the entity bean instance. For example,
@Stateful
@Name("account")
public class AccountManager extends AbstractMutable
{
private Account account; // an entity bean
@Unwrap
public void getAccount()
{
return account;
}
...
}
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Factory and manager components
Note that the EntityHome class in the Seam Application Framework provides a great example of
managing an entity bean instance using a Seam component.
4.8. Factory and manager components
We often need to work with objects that are not Seam components. But we still want to be able to
inject them into our components using @In and use them in value and method binding expressions,
etc. Sometimes, we even need to tie them into the Seam context lifecycle (@Destroy, for example).
So the Seam contexts can contain objects which are not Seam components, and Seam provides a
couple of nice features that make it easier to work with non-component objects bound to contexts.
The factory component pattern lets a Seam component act as the instantiator for a non-component
object. A factory method will be called when a context variable is referenced but has no value
bound to it. We define factory methods using the @Factory annotation. The factory method binds
a value to the context variable, and determines the scope of the bound value. There are two styles
of factory method. The first style returns a value, which is bound to the context by Seam:
@Factory(scope=CONVERSATION)
public List<Customer> getCustomerList() {
return ... ;
}
The second style is a method of type void which binds the value to the context variable itself:
@DataModel List<Customer> customerList;
@Factory("customerList")
public void initCustomerList() {
customerList = ... ;
}
In both cases, the factory method is called when we reference the customerList context variable
and its value is null, and then has no further part to play in the lifecycle of the value. An even more
powerful pattern is the manager component pattern. In this case, we have a Seam component
that is bound to a context variable, that manages the value of the context variable, while remaining
invisible to clients.
A manager component is any component with an @Unwrap method. This method returns the value
that will be visable to clients, and is called every time a context variable is referenced.
@Name("customerList")
@Scope(CONVERSATION)
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public class CustomerListManager
{
...
@Unwrap
public List<Customer> getCustomerList() {
return ... ;
}
}
The manager component pattern is especially useful if we have an object where you need more
control over the lifecycle of the component. For example, if you have a heavyweight object that
needs a cleanup operation when the context ends you could @Unwrap the object, and perform
cleanup in the @Destroy method of the manager component.
@Name("hens")
@Scope(APPLICATION)
public class HenHouse {
Set<Hen> hens;
@In(required=false) Hen hen;
@Unwrap
public List<Hen> getHens() {
if (hens == null) {
// Setup our hens
}
return hens;
}
@Observer({"chickBorn", "chickenBoughtAtMarket"})
public addHen() {
hens.add(hen);
}
@Observer("chickenSoldAtMarket")
public removeHen() {
hens.remove(hen);
}
@Observer("foxGetsIn")
public removeAllHens() {
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Factory and manager components
hens.clear();
}
...
}
Here the managed component observes many events which change the underlying object. The
component manages these actions itself, and because the object is unwrapped on every access,
a consistent view is provided.
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Chapter 5.
Configuring Seam components
The philosophy of minimizing XML-based configuration is extremely strong in Seam.
Nevertheless, there are various reasons why we might want to configure a Seam component
using XML: to isolate deployment-specific information from the Java code, to enable the creation
of re-usable frameworks, to configure Seam's built-in functionality, etc. Seam provides two basic
approaches to configuring components: configuration via property settings in a properties file or
in web.xml, and configuration via components.xml.
5.1. Configuring components via property settings
Seam components may be provided with configuration properties either via servlet context
parameters, or via a properties file named seam.properties in the root of the classpath.
The configurable Seam component must expose JavaBeans-style property setter methods
for the configurable attributes. If a Seam component named com.jboss.myapp.settings
has a setter method named setLocale(), we can provide a property named
com.jboss.myapp.settings.locale in the seam.properties file or as a servlet context
parameter, and Seam will set the value of the locale attribute whenever it instantiates the
component.
The same mechanism is used to configure Seam itself. For example, to set the conversation
timeout, we provide a value for org.jboss.seam.core.manager.conversationTimeout
in web.xml or seam.properties. (There is a built-in Seam component named
org.jboss.seam.core.manager with a setter method named setConversationTimeout().)
5.2. Configuring components via components.xml
The components.xml file is a bit more powerful than property settings. It lets you:
• Configure components that have been installed automatically—including both built-in
components, and application components that have been annotated with the @Name annotation
and picked up by Seam's deployment scanner.
• Install classes with no @Name annotation as Seam components—this is most useful for certain
kinds of infrastructural components which can be installed multiple times different names (for
example Seam-managed persistence contexts).
• Install components that do have a @Name annotation but are not installed by default because of
an @Install annotation that indicates the component should not be installed.
• Override the scope of a component.
A components.xml file may appear in one of three different places:
• The WEB-INF directory of a war.
• The META-INF directory of a jar.
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• Any directory of a jar that contains classes with an @Name annotation.
Usually, Seam components are installed when the deployment scanner discovers a class
with a @Name annotation sitting in an archive with a seam.properties file or a META-INF/
components.xml file. (Unless the component has an @Install annotation indicating it should not
be installed by default.) The components.xml file lets us handle special cases where we need
to override the annotations.
For example, the following components.xml file installs jBPM:
<components xmlns="http://jboss.com/products/seam/components"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:bpm="http://jboss.com/products/seam/bpm">
<bpm:jbpm/>
</components>
This example does the same thing:
<components>
<component class="org.jboss.seam.bpm.Jbpm"/>
</components>
This one installs and configures two different Seam-managed persistence contexts:
<components xmlns="http://jboss.com/products/seam/components"
xmlns:persistence="http://jboss.com/products/seam/persistence"
<persistence:managed-persistence-context name="customerDatabase"
persistence-unit-jndi-name="java:/customerEntityManagerFactory"/>
<persistence:managed-persistence-context name="accountingDatabase"
persistence-unit-jndi-name="java:/accountingEntityManagerFactory"/>
</components>
As does this one:
<components>
<component name="customerDatabase"
class="org.jboss.seam.persistence.ManagedPersistenceContext">
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<property name="persistenceUnitJndiName">java:/customerEntityManagerFactory</
property>
</component>
<component name="accountingDatabase"
class="org.jboss.seam.persistence.ManagedPersistenceContext">
<property name="persistenceUnitJndiName">java:/accountingEntityManagerFactory</
property>
</component>
</components>
This example creates a session-scoped Seam-managed persistence context (this is not
recommended in practice):
<components xmlns="http://jboss.com/products/seam/components"
xmlns:persistence="http://jboss.com/products/seam/persistence"
<persistence:managed-persistence-context name="productDatabase"
scope="session"
persistence-unit-jndi-name="java:/productEntityManagerFactory"/>
</components>
<components>
<component name="productDatabase"
scope="session"
class="org.jboss.seam.persistence.ManagedPersistenceContext">
<property name="persistenceUnitJndiName">java:/productEntityManagerFactory</property>
</component>
</components>
It is common to use the auto-create option for infrastructural objects like persistence contexts,
which saves you from having to explicitly specify create=true when you use the @In annotation.
<components xmlns="http://jboss.com/products/seam/components"
xmlns:persistence="http://jboss.com/products/seam/persistence"
<persistence:managed-persistence-context name="productDatabase"
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auto-create="true"
persistence-unit-jndi-name="java:/productEntityManagerFactory"/>
</components>
<components>
<component name="productDatabase"
auto-create="true"
class="org.jboss.seam.persistence.ManagedPersistenceContext">
<property name="persistenceUnitJndiName">java:/productEntityManagerFactory</property>
</component>
</components>
The <factory> declaration lets you specify a value or method binding expression that will be
evaluated to initialize the value of a context variable when it is first referenced.
<components>
<factory
scope="CONVERSATION"/>
name="contact"
method="#{contactManager.loadContact}"
</components>
You can create an "alias" (a second name) for a Seam component like so:
<components>
<factory name="user" value="#{actor}" scope="STATELESS"/>
</components>
You can even create an "alias" for a commonly used expression:
<components>
<factory name="contact" value="#{contactManager.contact}" scope="STATELESS"/>
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Fine-grained configuration files
</components>
It is especially common to see the use of auto-create="true" with the <factory> declaration:
<components>
<factory name="session" value="#{entityManager.delegate}" scope="STATELESS" autocreate="true"/>
</components>
Sometimes we want to reuse the same components.xml file with minor changes during
both deployment and testing. Seam lets you place wildcards of the form @[email protected] in the
components.xml file which can be replaced either by your Ant build script (at deployment time) or
by providing a file named components.properties in the classpath (at development time). You'll
see this approach used in the Seam examples.
5.3. Fine-grained configuration files
If you have a large number of components that need to be configured in XML, it makes much
more sense to split up the information in components.xml into many small files. Seam lets you
put configuration for a class named, for example, com.helloworld.Hello in a resource named
com/helloworld/Hello.component.xml. (You might be familiar with this pattern, since it is the
same one we use in Hibernate.) The root element of the file may be either a <components> or
<component> element.
The first option lets you define multiple components in the file:
<components>
<component class="com.helloworld.Hello" name="hello">
<property name="name">#{user.name}</property>
</component>
<factory name="message" value="#{hello.message}"/>
</components>
The second option only lets you define or configure one component, but is less noisy:
<component name="hello">
<property name="name">#{user.name}</property>
</component>
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In the second option, the class name is implied by the file in which the component definition
appears.
Alternatively, you may put configuration for all classes in the com.helloworld package in com/
helloworld/components.xml.
5.4. Configurable property types
Properties of string, primitive or primitive wrapper type may be configured just as you would expect:
org.jboss.seam.core.manager.conversationTimeout 60000
<core:manager conversation-timeout="60000"/>
<component name="org.jboss.seam.core.manager">
<property name="conversationTimeout">60000</property>
</component>
Arrays, sets and lists of strings or primitives are also supported:
org.jboss.seam.bpm.jbpm.processDefinitions order.jpdl.xml, return.jpdl.xml, inventory.jpdl.xml
<bpm:jbpm>
<bpm:process-definitions>
<value>order.jpdl.xml</value>
<value>return.jpdl.xml</value>
<value>inventory.jpdl.xml</value>
</bpm:process-definitions>
</bpm:jbpm>
<component name="org.jboss.seam.bpm.jbpm">
<property name="processDefinitions">
<value>order.jpdl.xml</value>
<value>return.jpdl.xml</value>
<value>inventory.jpdl.xml</value>
</property>
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Using XML Namespaces
</component>
Even maps with String-valued keys and string or primitive values are supported:
<component name="issueEditor">
<property name="issueStatuses">
<key>open</key> <value>open issue</value>
<key>resolved</key> <value>issue resolved by developer</value>
<key>closed</key> <value>resolution accepted by user</value>
</property>
</component>
Finally, you may wire together components using a value-binding expression. Note that this is
quite different to injection using @In, since it happens at component instantiation time instead of
invocation time. It is therefore much more similar to the dependency injection facilities offered by
traditional IoC containers like JSF or Spring.
<drools:managed-working-memory
base="#{policyPricingRules}"/>
name="policyPricingWorkingMemory"
rule-
<component name="policyPricingWorkingMemory"
class="org.jboss.seam.drools.ManagedWorkingMemory">
<property name="ruleBase">#{policyPricingRules}</property>
</component>
5.5. Using XML Namespaces
Throughout the examples, there have been two competing ways of declaring components: with
and without the use of XML namespaces. The following shows a typical components.xml file
without namespaces:
<?xml version="1.0" encoding="UTF-8"?>
<components xmlns="http://jboss.com/products/seam/components"
xsi:schemaLocation="http://jboss.com/products/seam/components http://jboss.com/
products/seam/components-2.1.xsd">
<component class="org.jboss.seam.core.init">
<property name="debug">true</property>
<property name="jndiPattern">@[email protected]</property>
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</component>
</components>
As you can see, this is somewhat verbose. Even worse, the component and attribute names
cannot be validated at development time.
The namespaced version looks like this:
<?xml version="1.0" encoding="UTF-8"?>
<components xmlns="http://jboss.com/products/seam/components"
xmlns:core="http://jboss.com/products/seam/core"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation=
"http://jboss.com/products/seam/core http://jboss.com/products/seam/core-2.1.xsd
http://jboss.com/products/seam/components http://jboss.com/products/seam/
components-2.1.xsd">
<core:init debug="true" jndi-pattern="@[email protected]"/>
</components>
Even though the schema declarations are verbose, the actual XML content is lean and easy to
understand. The schemas provide detailed information about each component and the attributes
available, allowing XML editors to offer intelligent autocomplete. The use of namespaced elements
makes generating and maintaining correct components.xml files much simpler.
Now, this works great for the built-in Seam components, but what about user components? There
are two options. First, Seam supports mixing the two models, allowing the use of the generic
<component> declarations for user components, along with namespaced declarations for builtin components. But even better, Seam allows you to quickly declare namespaces for your own
components.
Any Java package can be associated with an XML namespace by annotating the package with
the @Namespace annotation. (Package-level annotations are declared in a file named packageinfo.java in the package directory.) Here is an example from the seampay demo:
@Namespace(value="http://jboss.com/products/seam/examples/seampay")
package org.jboss.seam.example.seampay;
import org.jboss.seam.annotations.Namespace;
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That is all you need to do to use the namespaced style in components.xml! Now we can write:
<components xmlns="http://jboss.com/products/seam/components"
xmlns:pay="http://jboss.com/products/seam/examples/seampay"
... >
<pay:payment-home new-instance="#{newPayment}"
created-message="Created a new payment to #{newPayment.payee}" />
<pay:payment name="newPayment"
payee="Somebody"
account="#{selectedAccount}"
payment-date="#{currentDatetime}"
created-date="#{currentDatetime}" />
...
</components>
Or:
<components xmlns="http://jboss.com/products/seam/components"
xmlns:pay="http://jboss.com/products/seam/examples/seampay"
... >
<pay:payment-home>
<pay:new-instance>"#{newPayment}"</pay:new-instance>
<pay:created-message>Created a new payment to #{newPayment.payee}</pay:createdmessage>
</pay:payment-home>
<pay:payment name="newPayment">
<pay:payee>Somebody"</pay:payee>
<pay:account>#{selectedAccount}</pay:account>
<pay:payment-date>#{currentDatetime}</pay:payment-date>
<pay:created-date>#{currentDatetime}</pay:created-date>
</pay:payment>
...
</components>
These examples illustrate the two usage models of a namespaced element. In the first declaration,
the <pay:payment-home> references the paymentHome component:
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package org.jboss.seam.example.seampay;
...
@Name("paymentHome")
public class PaymentController
extends EntityHome<Payment>
{
...
}
The element name is the hyphenated form of the component name. The attributes of the element
are the hyphenated form of the property names.
In the second declaration, the <pay:payment> element refers to the Payment class in the
org.jboss.seam.example.seampay package. In this case Payment is an entity that is being
declared as a Seam component:
package org.jboss.seam.example.seampay;
...
@Entity
public class Payment
implements Serializable
{
...
}
If we want validation and autocompletion to work for user-defined components, we will need a
schema. Seam does not yet provide a mechanism to automatically generate a schema for a set of
components, so it is necessary to generate one manually. The schema definitions for the standard
Seam packages can be used for guidance.
The following are the the namespaces used by Seam:
• components — http://jboss.com/products/seam/components
• core — http://jboss.com/products/seam/core
• drools — http://jboss.com/products/seam/drools
• framework — http://jboss.com/products/seam/framework
• jms — http://jboss.com/products/seam/jms
• remoting — http://jboss.com/products/seam/remoting
• theme — http://jboss.com/products/seam/theme
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Using XML Namespaces
• security — http://jboss.com/products/seam/security
• mail — http://jboss.com/products/seam/mail
• web — http://jboss.com/products/seam/web
• pdf — http://jboss.com/products/seam/pdf
• spring — http://jboss.com/products/seam/spring
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Chapter 6.
Events, interceptors and exception
handling
Complementing the contextual component model, there are two further basic concepts that
facilitate the extreme loose-coupling that is the distinctive feature of Seam applications. The first
is a strong event model where events may be mapped to event listeners via JSF-like method
binding expressions. The second is the pervasive use of annotations and interceptors to apply
cross-cutting concerns to components which implement business logic.
6.1. Seam events
The Seam component model was developed for use with event-driven applications, specifically to
enable the development of fine-grained, loosely-coupled components in a fine-grained eventing
model. Events in Seam come in several types, most of which we have already seen:
• JSF events
• jBPM transition events
• Seam page actions
• Seam component-driven events
• Seam contextual events
All of these various kinds of events are mapped to Seam components via JSF EL method binding
expressions. For a JSF event, this is defined in the JSF template:
<h:commandButton value="Click me!" action="#{helloWorld.sayHello}"/>
For a jBPM transition event, it is specified in the jBPM process definition or pageflow definition:
<start-page name="hello" view-id="/hello.jsp">
<transition to="hello">
<action expression="#{helloWorld.sayHello}"/>
</transition>
</start-page>
You can find out more information about JSF events and jBPM events elsewhere. Let's
concentrate for now upon the two additional kinds of events defined by Seam.
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6.2. Page actions
A Seam page action is an event that occurs just before we render a page. We declare page actions
in WEB-INF/pages.xml. We can define a page action for either a particular JSF view id:
<pages>
<page view-id="/hello.jsp" action="#{helloWorld.sayHello}"/>
</pages>
Or we can use a * wildcard as a suffix to the view-id to specify an action that applies to all view
ids that match the pattern:
<pages>
<page view-id="/hello/*" action="#{helloWorld.sayHello}"/>
</pages>
If multiple wildcarded page actions match the current view-id, Seam will call all the actions, in
order of least-specific to most-specific.
The page action method can return a JSF outcome. If the outcome is non-null, Seam will use the
defined navigation rules to navigate to a view.
Furthermore, the view id mentioned in the <page> element need not correspond to a real JSP or
Facelets page! So, we can reproduce the functionality of a traditional action-oriented framework
like Struts or WebWork using page actions. For example:
TODO: translate struts action into page action
This is quite useful if you want to do complex things in response to non-faces requests (for
example, HTTP GET requests).
Multiple or conditional page actions my be specified using the <action> tag:
<pages>
<page view-id="/hello.jsp">
<action execute="#{helloWorld.sayHello}" if="#{not validation.failed}"/>
<action execute="#{hitCount.increment}"/>
</page>
</pages>
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6.3. Page parameters
A JSF faces request (a form submission) encapsulates both an "action" (a method binding) and
"parameters" (input value bindings). A page action might also needs parameters!
Since GET requests are bookmarkable, page parameters are passed as human-readable request
parameters. (Unlike JSF form inputs, which are anything but!)
You can use page parameters with or without an action method.
6.3.1. Mapping request parameters to the model
Seam lets us provide a value binding that maps a named request parameter to an attribute of a
model object.
<pages>
<page view-id="/hello.jsp" action="#{helloWorld.sayHello}">
<param name="firstName" value="#{person.firstName}"/>
<param name="lastName" value="#{person.lastName}"/>
</page>
</pages>
The <param> declaration is bidirectional, just like a value binding for a JSF input:
• When a non-faces (GET) request for the view id occurs, Seam sets the value of the named
request parameter onto the model object, after performing appropriate type conversions.
• Any <s:link> or <s:button> transparently includes the request parameter. The value of the
parameter is determined by evaluating the value binding during the render phase (when the
<s:link> is rendered).
• Any navigation rule with a <redirect/> to the view id transparently includes the request
parameter. The value of the parameter is determined by evaluating the value binding at the end
of the invoke application phase.
• The value is transparently propagated with any JSF form submission for the page with the given
view id. This means that view parameters behave like PAGE-scoped context variables for faces
requests.
The essential idea behind all this is that however we get from any other page to /hello.jsp (or
from /hello.jsp back to /hello.jsp), the value of the model attribute referred to in the value
binding is "remembered", without the need for a conversation (or other server-side state).
6.4. Propagating request parameters
If just the name attribute is specified then the request parameter is propagated using the PAGE
context (it isn't mapped to model property).
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<pages>
<page view-id="/hello.jsp" action="#{helloWorld.sayHello}">
<param name="firstName" />
<param name="lastName" />
</page>
</pages>
Propagation of page parameters is especially useful if you want to build multi-layer master-detail
CRUD pages. You can use it to "remember" which view you were previously on (e.g. when
pressing the Save button), and which entity you were editing.
• Any <s:link> or <s:button> transparently propagates the request parameter if that parameter
is listed as a page parameter for the view.
• The value is transparently propagated with any JSF form submission for the page with the given
view id. (This means that view parameters behave like PAGE-scoped context variables for faces
requests.
This all sounds pretty complex, and you're probably wondering if such an exotic construct is really
worth the effort. Actually, the idea is very natural once you "get it". It is definitely worth taking the
time to understand this stuff. Page parameters are the most elegant way to propagate state across
a non-faces request. They are especially cool for problems like search screens with bookmarkable
results pages, where we would like to be able to write our application code to handle both POST
and GET requests with the same code. Page parameters eliminate repetitive listing of request
parameters in the view definition and make redirects much easier to code.
6.5. Conversion and Validation
You can specify a JSF converter for complex model propreties:
<pages>
<page view-id="/calculator.jsp" action="#{calculator.calculate}">
<param name="x" value="#{calculator.lhs}"/>
<param name="y" value="#{calculator.rhs}"/>
<param name="op" converterId="com.my.calculator.OperatorConverter"
value="#{calculator.op}"/>
</page>
</pages>
Alternatively:
<pages>
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<page view-id="/calculator.jsp" action="#{calculator.calculate}">
<param name="x" value="#{calculator.lhs}"/>
<param name="y" value="#{calculator.rhs}"/>
<param name="op" converter="#{operatorConverter}" value="#{calculator.op}"/>
</page>
</pages>
JSF validators, and required="true" may also be used:
<pages>
<page view-id="/blog.xhtml">
<param name="date"
value="#{blog.date}"
validatorId="com.my.blog.PastDate"
required="true"/>
</page>
</pages>
Alternatively:
<pages>
<page view-id="/blog.xhtml">
<param name="date"
value="#{blog.date}"
validator="#{pastDateValidator}"
required="true"/>
</page>
</pages>
Even better, model-based Hibernate validator annotations are automatically recognized and
validated.
When type conversion or validation fails, a global FacesMessage is added to the FacesContext.
6.6. Navigation
You can use standard JSF navigation rules defined in faces-config.xml in a Seam application.
However, JSF navigation rules have a number of annoying limitations:
• It is not possible to specify request parameters to be used when redirecting.
• It is not possible to begin or end conversations from a rule.
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• Rules work by evaluating the return value of the action method; it is not possible to evaluate
an arbitrary EL expression.
A further problem is that "orchestration" logic gets scattered between pages.xml and facesconfig.xml. It's better to unify this logic into pages.xml.
This JSF navigation rule:
<navigation-rule>
<from-view-id>/editDocument.xhtml</from-view-id>
<navigation-case>
<from-action>#{documentEditor.update}</from-action>
<from-outcome>success</from-outcome>
<to-view-id>/viewDocument.xhtml</to-view-id>
<redirect/>
</navigation-case>
</navigation-rule>
Can be rewritten as follows:
<page view-id="/editDocument.xhtml">
<navigation from-action="#{documentEditor.update}">
<rule if-outcome="success">
<redirect view-id="/viewDocument.xhtml"/>
</rule>
</navigation>
</page>
But it would be even nicer if we didn't have to pollute our DocumentEditor component with stringvalued return values (the JSF outcomes). So Seam lets us write:
<page view-id="/editDocument.xhtml">
<navigation from-action="#{documentEditor.update}"
evaluate="#{documentEditor.errors.size}">
<rule if-outcome="0">
<redirect view-id="/viewDocument.xhtml"/>
</rule>
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</navigation>
</page>
Or even:
<page view-id="/editDocument.xhtml">
<navigation from-action="#{documentEditor.update}">
<rule if="#{documentEditor.errors.empty}">
<redirect view-id="/viewDocument.xhtml"/>
</rule>
</navigation>
</page>
The first form evaluates a value binding to determine the outcome value to be used by the
subsequent rules. The second approach ignores the outcome and evaluates a value binding for
each possible rule.
Of course, when an update succeeds, we probably want to end the current conversation. We can
do that like this:
<page view-id="/editDocument.xhtml">
<navigation from-action="#{documentEditor.update}">
<rule if="#{documentEditor.errors.empty}">
<end-conversation/>
<redirect view-id="/viewDocument.xhtml"/>
</rule>
</navigation>
</page>
As we've ended conversation any subsequent requests won't know which document we are
interested in. We can pass the document id as a request parameter which also makes the view
bookmarkable:
<page view-id="/editDocument.xhtml">
<navigation from-action="#{documentEditor.update}">
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<rule if="#{documentEditor.errors.empty}">
<end-conversation/>
<redirect view-id="/viewDocument.xhtml">
<param name="documentId" value="#{documentEditor.documentId}"/>
</redirect>
</rule>
</navigation>
</page>
Null outcomes are a special case in JSF. The null outcome is interpreted to mean "redisplay the
page". The following navigation rule matches any non-null outcome, but not the null outcome:
<page view-id="/editDocument.xhtml">
<navigation from-action="#{documentEditor.update}">
<rule>
<render view-id="/viewDocument.xhtml"/>
</rule>
</navigation>
</page>
If you want to perform navigation when a null outcome occurs, use the following form instead:
<page view-id="/editDocument.xhtml">
<navigation from-action="#{documentEditor.update}">
<render view-id="/viewDocument.xhtml"/>
</navigation>
</page>
The view-id may be given as a JSF EL expression:
<page view-id="/editDocument.xhtml">
<navigation>
<rule if-outcome="success">
<redirect view-id="/#{userAgent}/displayDocument.xhtml"/>
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Fine-grained files for definition of navigation,
page actions and parameters
</rule>
</navigation>
</page>
6.7. Fine-grained files for definition of navigation, page
actions and parameters
If you have a lot of different page actions and page parameters, or even just a lot of navigation
rules, you will almost certainly want to split the declarations up over multiple files. You can define
actions and parameters for a page with the view id /calc/calculator.jsp in a resource named
calc/calculator.page.xml. The root element in this case is the <page> element, and the view
id is implied:
<page action="#{calculator.calculate}">
<param name="x" value="#{calculator.lhs}"/>
<param name="y" value="#{calculator.rhs}"/>
<param name="op" converter="#{operatorConverter}" value="#{calculator.op}"/>
</page>
6.8. Component-driven events
Seam components can interact by simply calling each others methods. Stateful components may
even implement the observer/observable pattern. But to enable components to interact in a more
loosely-coupled fashion than is possible when the components call each others methods directly,
Seam provides component-driven events.
We specify event listeners (observers) in components.xml.
<components>
<event type="hello">
<action execute="#{helloListener.sayHelloBack}"/>
<action execute="#{logger.logHello}"/>
</event>
</components>
Where the event type is just an arbitrary string.
When an event occurs, the actions registered for that event will be called in the order they appear
in components.xml. How does a component raise an event? Seam provides a built-in component
for this.
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@Name("helloWorld")
public class HelloWorld {
public void sayHello() {
FacesMessages.instance().add("Hello World!");
Events.instance().raiseEvent("hello");
}
}
Or you can use an annotation.
@Name("helloWorld")
public class HelloWorld {
@RaiseEvent("hello")
public void sayHello() {
FacesMessages.instance().add("Hello World!");
}
}
Notice that this event producer has no dependency upon event consumers. The event listener
may now be implemented with absolutely no dependency upon the producer:
@Name("helloListener")
public class HelloListener {
public void sayHelloBack() {
FacesMessages.instance().add("Hello to you too!");
}
}
The method binding defined in components.xml above takes care of mapping the event to the
consumer. If you don't like futzing about in the components.xml file, you can use an annotation
instead:
@Name("helloListener")
public class HelloListener {
@Observer("hello")
public void sayHelloBack() {
FacesMessages.instance().add("Hello to you too!");
}
}
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Contextual events
You might wonder why I've not mentioned anything about event objects in this discussion. In
Seam, there is no need for an event object to propagate state between event producer and listener.
State is held in the Seam contexts, and is shared between components. However, if you really
want to pass an event object, you can:
@Name("helloWorld")
public class HelloWorld {
private String name;
public void sayHello() {
FacesMessages.instance().add("Hello World, my name is #0.", name);
Events.instance().raiseEvent("hello", name);
}
}
@Name("helloListener")
public class HelloListener {
@Observer("hello")
public void sayHelloBack(String name) {
FacesMessages.instance().add("Hello #0!", name);
}
}
6.9. Contextual events
Seam defines a number of built-in events that the application can use to perform special kinds of
framework integration. The events are:
• org.jboss.seam.validationFailed — called when JSF validation fails
• org.jboss.seam.noConversation — called when there is no long running conversation and
a long running conversation is required
• org.jboss.seam.preSetVariable.<name> — called when the context variable <name> is set
• org.jboss.seam.postSetVariable.<name> — called when the context variable <name> is set
• org.jboss.seam.preRemoveVariable.<name> — called when the context variable <name> is
unset
• org.jboss.seam.postRemoveVariable.<name> — called when the context variable <name>
is unset
• org.jboss.seam.preDestroyContext.<SCOPE> — called before the <SCOPE> context is
destroyed
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• org.jboss.seam.postDestroyContext.<SCOPE> — called after the <SCOPE> context is
destroyed
• org.jboss.seam.beginConversation — called whenever a long-running conversation begins
• org.jboss.seam.endConversation — called whenever a long-running conversation ends
• org.jboss.seam.conversationTimeout— called when a conversation timeout occurs. The
conversation id is passed as a parameter.
• org.jboss.seam.beginPageflow — called when a pageflow begins
• org.jboss.seam.beginPageflow.<name> — called when the pageflow <name> begins
• org.jboss.seam.endPageflow — called when a pageflow ends
• org.jboss.seam.endPageflow.<name> — called when the pageflow <name> ends
• org.jboss.seam.createProcess.<name> — called when the process <name> is created
• org.jboss.seam.endProcess.<name> — called when the process <name> ends
• org.jboss.seam.initProcess.<name> — called when the process <name> is associated
with the conversation
• org.jboss.seam.initTask.<name> — called when the task <name> is associated with the
conversation
• org.jboss.seam.startTask.<name> — called when the task <name> is started
• org.jboss.seam.endTask.<name> — called when the task <name> is ended
• org.jboss.seam.postCreate.<name> — called when the component <name> is created
• org.jboss.seam.preDestroy.<name> — called when the component <name> is destroyed
• org.jboss.seam.beforePhase — called before the start of a JSF phase
• org.jboss.seam.afterPhase — called after the end of a JSF phase
• org.jboss.seam.postInitialization — called when Seam has initialized and started up
all components
• org.jboss.seam.postAuthenticate.<name> — called after a user is authenticated
• org.jboss.seam.preAuthenticate.<name> — called before attempting to authenticate a
user
• org.jboss.seam.notLoggedIn — called there is no authenticated user and authentication is
required
• org.jboss.seam.rememberMe — occurs when Seam security detects the username in a cookie
• org.jboss.seam.exceptionHandled.<type> — called when an uncaught exception is
handled by Seam
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• org.jboss.seam.exceptionHandled — called when an uncaught exception is handled by
Seam
• org.jboss.seam.exceptionNotHandled — called when there was no handler for an uncaught
exception
• org.jboss.seam.afterTransactionSuccess — called when a transaction succeeds in the
Seam Application Framework
• org.jboss.seam.afterTransactionSuccess.<name> — called when a transaction succeeds
in the Seam Application Framework which manages an entity called <name>
Seam components may observe any of these events in just the same way they observe any other
component-driven events.
6.10. Seam interceptors
EJB 3.0 introduced a standard interceptor model for session bean components. To add an
interceptor to a bean, you need to write a class with a method annotated @AroundInvoke and
annotate the bean with an @Interceptors annotation that specifies the name of the interceptor
class. For example, the following interceptor checks that the user is logged in before allowing
invoking an action listener method:
public class LoggedInInterceptor {
@AroundInvoke
public Object checkLoggedIn(InvocationContext invocation) throws Exception {
boolean isLoggedIn = Contexts.getSessionContext().get("loggedIn")!=null;
if (isLoggedIn) {
//the user is already logged in
return invocation.proceed();
}
else {
//the user is not logged in, fwd to login page
return "login";
}
}
}
To apply this interceptor to a session bean which acts as an action listener, we must
annotate the session bean @Interceptors(LoggedInInterceptor.class). This is a somewhat
ugly annotation. Seam builds upon the interceptor framework in EJB3 by allowing you
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to use @Interceptors as a meta-annotation for class level interceptors (those annotated
@Target(TYPE)). In our example, we would create an @LoggedIn annotation, as follows:
@Target(TYPE)
@Retention(RUNTIME)
@Interceptors(LoggedInInterceptor.class)
public @interface LoggedIn {}
We can now simply annotate our action listener bean with @LoggedIn to apply the interceptor.
@Stateless
@Name("changePasswordAction")
@LoggedIn
@Interceptors(SeamInterceptor.class)
public class ChangePasswordAction implements ChangePassword {
...
public String changePassword() { ... }
}
If interceptor ordering is important (it usually is), you can add @Interceptor annotations to your
interceptor classes to specify a partial order of interceptors.
@Interceptor(around={BijectionInterceptor.class,
ValidationInterceptor.class,
ConversationInterceptor.class},
within=RemoveInterceptor.class)
public class LoggedInInterceptor
{
...
}
You can even have a "client-side" interceptor, that runs around any of the built-in functionality
of EJB3:
@Interceptor(type=CLIENT)
public class LoggedInInterceptor
{
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...
}
EJB interceptors are stateful, with a lifecycle that is the same as the component they intercept. For
interceptors which do not need to maintain state, Seam lets you get a performance optimization
by specifying @Interceptor(stateless=true).
Much of the functionality of Seam is implemented as a set of built-in Seam interceptors, including
the interceptors named in the previous example. You don't have to explicitly specify these
interceptors by annotating your components; they exist for all interceptable Seam components.
You can even use Seam interceptors with JavaBean components, not just EJB3 beans!
EJB defines interception not only for business methods (using @AroundInvoke), but also for
the lifecycle methods @PostConstruct, @PreDestroy, @PrePassivate and @PostActive. Seam
supports all these lifecycle methods on both component and interceptor not only for EJB3 beans,
but also for JavaBean components (except @PreDestroy which is not meaningful for JavaBean
components).
6.11. Managing exceptions
JSF is surprisingly limited when it comes to exception handling. As a partial workaround for this
problem, Seam lets you define how a particular class of exception is to be treated by annotating
the exception class, or declaring the exception class in an XML file. This facility is meant to
be combined with the EJB 3.0-standard @ApplicationException annotation which specifies
whether the exception should cause a transaction rollback.
6.11.1. Exceptions and transactions
EJB specifies well-defined rules that let us control whether an exception immediately
marks the current transaction for rollback when it is thrown by a business method of the
bean: system exceptions always cause a transaction rollback, application exceptions do not
cause a rollback by default, but they do if @ApplicationException(rollback=true) is
specified. (An application exception is any checked exception, or any unchecked exception
annotated @ApplicationException. A system exception is any unchecked exception without an
@ApplicationException annotation.)
Note that there is a difference between marking a transaction for rollback, and actually rolling it
back. The exception rules say that the transaction should be marked rollback only, but it may still
be active after the exception is thrown.
Seam applies the EJB 3.0 exception rollback rules also to Seam JavaBean components.
But these rules only apply in the Seam component layer. What about an exception that is uncaught
and propagates out of the Seam component layer, and out of the JSF layer? Well, it is always
wrong to leave a dangling transaction open, so Seam rolls back any active transaction when an
exception occurs and is uncaught in the Seam component layer.
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6.11.2. Enabling Seam exception handling
To enable Seam's exception handling, we need to make sure we have the master servlet filter
declared in web.xml:
<filter>
<filter-name>Seam Filter</filter-name>
<filter-class>org.jboss.seam.servlet.SeamFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>Seam Filter</filter-name>
<url-pattern>*.seam</url-pattern>
</filter-mapping>
You may also need to disable Facelets development mode in web.xml and Seam debug mode in
components.xml if you want your exception handlers to fire.
6.11.3. Using annotations for exception handling
The following exception results in a HTTP 404 error whenever it propagates out of the Seam
component layer. It does not roll back the current transaction immediately when thrown, but the
transaction will be rolled back if it the exception is not caught by another Seam component.
@HttpError(errorCode=404)
public class ApplicationException extends Exception { ... }
This exception results in a browser redirect whenever it propagates out of the Seam component
layer. It also ends the current conversation. It causes an immediate rollback of the current
transaction.
@Redirect(viewId="/failure.xhtml", end=true)
@ApplicationException(rollback=true)
public class UnrecoverableApplicationException extends RuntimeException { ... }
Note that @Redirect does not work for exceptions which occur during the render phase of the
JSF lifecycle.
You can also use EL to specify the viewId to redirect to.
This exception results in a redirect, along with a message to the user, when it propagates out of
the Seam component layer. It also immediately rolls back the current transaction.
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@Redirect(viewId="/error.xhtml", message="Unexpected error")
public class SystemException extends RuntimeException { ... }
6.11.4. Using XML for exception handling
Since we can't add annotations to all the exception classes we are interested in, Seam also lets
us specify this functionality in pages.xml.
<pages>
<exception class="javax.persistence.EntityNotFoundException">
<http-error error-code="404"/>
</exception>
<exception class="javax.persistence.PersistenceException">
<end-conversation/>
<redirect view-id="/error.xhtml">
<message>Database access failed</message>
</redirect>
</exception>
<exception>
<end-conversation/>
<redirect view-id="/error.xhtml">
<message>Unexpected failure</message>
</redirect>
</exception>
</pages>
The last <exception> declaration does not specify a class, and is a catch-all for any exception
for which handling is not otherwise specified via annotations or in pages.xml.
You can also use EL to specify the view-id to redirect to.
You can also access the handled exception instance through EL, Seam places it in the
conversation context, e.g. to access the message of the exception:
...
throw new AuthorizationException("You are not allowed to do this!");
<pages>
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<exception class="org.jboss.seam.security.AuthorizationException">
<end-conversation/>
<redirect view-id="/error.xhtml">
<message severity="WARN">#{org.jboss.seam.handledException.message}</message>
</redirect>
</exception>
</pages>
org.jboss.seam.handledException holds the nested exception that was actually handled
by an exception handler. The outermost (wrapper) exception is also available, as
org.jboss.seam.exception.
6.11.4.1. Suppressing exception logging
For the exception handlers defined in pages.xml, it is possible to declare the logging level at
which the exception will be logged, or to even suppress the exception being logged altogether. The
attributes log and logLevel can be used to control exception logging. By setting log="false" as
per the following example, then no log message will be generated when the specified exception
occurs:
<exception class="org.jboss.seam.security.NotLoggedInException" log="false">
<redirect view-id="/register.xhtml">
<message severity="warn">You must be a member to use this feature</message>
</redirect>
</exception>
If the log attribute is not specified, then it defaults to true (i.e. the exception will be logged).
Alternatively, you can specify the logLevel to control at which log level the exception will be
logged:
<exception class="org.jboss.seam.security.NotLoggedInException" logLevel="info">
<redirect view-id="/register.xhtml">
<message severity="warn">You must be a member to use this feature</message>
</redirect>
</exception>
The acceptable values for logLevel are: fatal, error, warn, info, debug or trace. If the
logLevel is not specified, or if an invalid value is configured, then it will default to error.
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Some common exceptions
6.11.5. Some common exceptions
If you are using JPA:
<exception class="javax.persistence.EntityNotFoundException">
<redirect view-id="/error.xhtml">
<message>Not found</message>
</redirect>
</exception>
<exception class="javax.persistence.OptimisticLockException">
<end-conversation/>
<redirect view-id="/error.xhtml">
<message>Another user changed the same data, please try again</message>
</redirect>
</exception>
If you are using the Seam Application Framework:
<exception class="org.jboss.seam.framework.EntityNotFoundException">
<redirect view-id="/error.xhtml">
<message>Not found</message>
</redirect>
</exception>
If you are using Seam Security:
<exception class="org.jboss.seam.security.AuthorizationException">
<redirect>
<message>You don't have permission to do this</message>
</redirect>
</exception>
<exception class="org.jboss.seam.security.NotLoggedInException">
<redirect view-id="/login.xhtml">
<message>Please log in first</message>
</redirect>
</exception>
And, for JSF:
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<exception class="javax.faces.application.ViewExpiredException">
<redirect view-id="/error.xhtml">
<message>Your session has timed out, please try again</message>
</redirect>
</exception>
A ViewExpiredException occurs if the user posts back to a page once their session has expired.
no-conversation-view-id and conversation-required give you finer grained control over
session expiration if you are inside a conversation.
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Chapter 7.
Conversations and workspace
management
It's time to understand Seam's conversation model in more detail.
Historically, the notion of a Seam "conversation" came about as a merger of three different ideas:
• The idea of a workspace, which I encountered in a project for the Victorian government in 2002.
In this project I was forced to implement workspace management on top of Struts, an experience
I pray never to repeat.
• The idea of an application transaction with optimistic semantics, and the realization that existing
frameworks based around a stateless architecture could not provide effective management of
extended persistence contexts. (The Hibernate team is truly fed up with copping the blame for
LazyInitializationExceptions, which are not really Hibernate's fault, but rather the fault of
the extremely limiting persistence context model supported by stateless architectures such as
the Spring framework or the traditional stateless session facade (anti)pattern in J2EE.)
• The idea of a workflow task.
By unifying these ideas and providing deep support in the framework, we have a powerful construct
that lets us build richer and more efficient applications with less code than before.
7.1. Seam's conversation model
The examples we have seen so far make use of a very simple conversation model that follows
these rules:
• There is always a conversation context active during the apply request values, process
validations, update model values, invoke application and render response phases of the JSF
request lifecycle.
• At the end of the restore view phase of the JSF request lifecycle, Seam attempts to restore
any previous long-running conversation context. If none exists, Seam creates a new temporary
conversation context.
• When an @Begin method is encountered, the temporary conversation context is promoted to
a long running conversation.
• When an @End method is encountered, any long-running conversation context is demoted to
a temporary conversation.
• At the end of the render response phase of the JSF request lifecycle, Seam stores the contents
of a long running conversation context or destroys the contents of a temporary conversation
context.
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• Any faces request (a JSF postback) will propagate the conversation context. By default, nonfaces requests (GET requests, for example) do not propagate the conversation context, but see
below for more information on this.
• If the JSF request lifecycle is foreshortened by a redirect, Seam transparently stores and
restores the current conversation context—unless the conversation was already ended via
@End(beforeRedirect=true).
Seam transparently propagates the conversation context (including the temporary conversation
context) across JSF postbacks and redirects. If you don't do anything special, a non-faces request
(a GET request for example) will not propagate the conversation context and will be processed in
a new temporary conversation. This is usually - but not always - the desired behavior.
If you want to propagate a Seam conversation across a non-faces request, you need to explicitly
code the Seam conversation id as a request parameter:
<a href="main.jsf?conversationId=#{conversation.id}">Continue</a>
Or, the more JSF-ish:
<h:outputLink value="main.jsf">
<f:param name="conversationId" value="#{conversation.id}"/>
<h:outputText value="Continue"/>
</h:outputLink>
If you use the Seam tag library, this is equivalent:
<h:outputLink value="main.jsf">
<s:conversationId/>
<h:outputText value="Continue"/>
</h:outputLink>
If you wish to disable propagation of the conversation context for a postback, a similar trick is used:
<h:commandLink action="main" value="Exit">
<f:param name="conversationPropagation" value="none"/>
</h:commandLink>
If you use the Seam tag library, this is equivalent:
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<h:commandLink action="main" value="Exit">
<s:conversationPropagation type="none"/>
</h:commandLink>
Note that disabling conversation context propagation is absolutely not the same thing as ending
the conversation.
The conversationPropagation request parameter, or the <s:conversationPropagation> tag
may even be used to begin and end conversation, or begin a nested conversation.
<h:commandLink action="main" value="Exit">
<s:conversationPropagation type="end"/>
</h:commandLink>
<h:commandLink action="main" value="Select Child">
<s:conversationPropagation type="nested"/>
</h:commandLink>
<h:commandLink action="main" value="Select Hotel">
<s:conversationPropagation type="begin"/>
</h:commandLink>
<h:commandLink action="main" value="Select Hotel">
<s:conversationPropagation type="join"/>
</h:commandLink>
This conversation model makes it easy to build applications which behave correctly with respect
to multi-window operation. For many applications, this is all that is needed. Some complex
applications have either or both of the following additional requirements:
• A conversation spans many smaller units of user interaction, which execute serially or even
concurrently. The smaller nested conversations have their own isolated set of conversation
state, and also have access to the state of the outer conversation.
• The user is able to switch between many conversations within the same browser window. This
feature is called workspace management.
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7.2. Nested conversations
A nested conversation is created by invoking a method marked @Begin(nested=true) inside
the scope of an existing conversation. A nested conversation has its own conversation context,
and also has read-only access to the context of the outer conversation. (It can read the
outer conversation's context variables, but not write to them.) When an @End is subsequently
encountered, the nested conversation will be destroyed, and the outer conversation will resume,
by "popping" the conversation stack. Conversations may be nested to any arbitrary depth.
Certain user activity (workspace management, or the back button) can cause the outer
conversation to be resumed before the inner conversation is ended. In this case it is possible
to have multiple concurrent nested conversations belonging to the same outer conversation.
If the outer conversation ends before a nested conversation ends, Seam destroys all nested
conversation contexts along with the outer context.
A conversation may be thought of as a continuable state. Nested conversations allow the
application to capture a consistent continuable state at various points in a user interaction, thus
insuring truly correct behavior in the face of backbuttoning and workspace management.
TODO: an example to show how a nested conversation prevents bad stuff happening when you
backbutton.
Usually, if a component exists in a parent conversation of the current nested conversation, the
nested conversation will use the same instance. Occasionally, it is useful to have a different
instance in each nested conversation, so that the component instance that exists in the parent
conversation is invisible to its child conversations. You can achieve this behavior by annotating
the component @PerNestedConversation.
7.3. Starting conversations with GET requests
JSF does not define any kind of action listener that is triggered when a page is accessed via a
non-faces request (for example, a HTTP GET request). This can occur if the user bookmarks the
page, or if we navigate to the page via an <h:outputLink>.
Sometimes we want to begin a conversation immediately the page is accessed. Since there is no
JSF action method, we can't solve the problem in the usual way, by annotating the action with
@Begin.
A further problem arises if the page needs some state to be fetched into a context variable. We've
already seen two ways to solve this problem. If that state is held in a Seam component, we can
fetch the state in a @Create method. If not, we can define a @Factory method for the context
variable.
If none of these options works for you, Seam lets you define a page action in the pages.xml file.
<pages>
<page view-id="/messageList.jsp" action="#{messageManager.list}"/>
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...
</pages>
This action method is called at the beginning of the render response phase, any time the page
is about to be rendered. If a page action returns a non-null outcome, Seam will process any
appropriate JSF and Seam navigation rules, possibly resulting in a completely different page being
rendered.
If all you want to do before rendering the page is begin a conversation, you could use a built-in
action method that does just that:
<pages>
<page view-id="/messageList.jsp" action="#{conversation.begin}"/>
...
</pages>
Note that you can also call this built-in action from a JSF control, and, similarly, you can use
#{conversation.end} to end conversations.
If you want more control, to join existing conversations or begin a nested conversion, to begin a
pageflow or an atomic conversation, you should use the <begin-conversation> element.
<pages>
<page view-id="/messageList.jsp">
<begin-conversation nested="true" pageflow="AddItem"/>
<page>
...
</pages>
There is also an <end-conversation> element.
<pages>
<page view-id="/home.jsp">
<end-conversation/>
<page>
...
</pages>
To solve the first problem, we now have five options:
• Annotate the @Create method with @Begin
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• Annotate the @Factory method with @Begin
• Annotate the Seam page action method with @Begin
• Use <begin-conversation> in pages.xml.
• Use #{conversation.begin} as the Seam page action method
7.4. Using <s:link> and <s:button>
JSF command links always perform a form submission via JavaScript, which breaks the web
browser's "open in new window" or "open in new tab" feature. In plain JSF, you need to
use an <h:outputLink> if you need this functionality. But there are two major limitations to
<h:outputLink>.
• JSF provides no way to attach an action listener to an <h:outputLink>.
• JSF does not propagate the selected row of a DataModel since there is no actual form
submission.
Seam provides the notion of a page action to help solve the first problem, but this does nothing
to help us with the second problem. We could work around this by using the RESTful approach
of passing a request parameter and requerying for the selected object on the server side. In
some cases—such as the Seam blog example application—this is indeed the best approach. The
RESTful style supports bookmarking, since it does not require server-side state. In other cases,
where we don't care about bookmarks, the use of @DataModel and @DataModelSelection is just
so convenient and transparent!
To fill in this missing functionality, and to make conversation propagation even simpler to manage,
Seam provides the <s:link> JSF tag.
The link may specify just the JSF view id:
<s:link view="/login.xhtml" value="Login"/>
Or, it may specify an action method (in which case the action outcome determines the page that
results):
<s:link action="#{login.logout}" value="Logout"/>
If you specify both a JSF view id and an action method, the 'view' will be used unless the action
method returns a non-null outcome:
<s:link view="/loggedOut.xhtml" action="#{login.logout}" value="Logout"/>
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The link automatically propagates the selected row of a DataModel using inside <h:dataTable>:
<s:link view="/hotel.xhtml" action="#{hotelSearch.selectHotel}" value="#{hotel.name}"/>
You can leave the scope of an existing conversation:
<s:link view="/main.xhtml" propagation="none"/>
You can begin, end, or nest conversations:
<s:link action="#{issueEditor.viewComment}" propagation="nest"/>
If the link begins a conversation, you can even specify a pageflow to be used:
<s:link action="#{documentEditor.getDocument}" propagation="begin"
pageflow="EditDocument"/>
The taskInstance attribute if for use in jBPM task lists:
<s:link action="#{documentApproval.approveOrReject}" taskInstance="#{task}"/>
(See the DVD Store demo application for examples of this.)
Finally, if you need the "link" to be rendered as a button, use <s:button>:
<s:button action="#{login.logout}" value="Logout"/>
7.5. Success messages
It is quite common to display a message to the user indicating success or failure of an action. It is
convenient to use a JSF FacesMessage for this. Unfortunately, a successful action often requires
a browser redirect, and JSF does not propagate faces messages across redirects. This makes it
quite difficult to display success messages in plain JSF.
The built in conversation-scoped Seam component named facesMessages solves this problem.
(You must have the Seam redirect filter installed.)
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@Name("editDocumentAction")
@Stateless
public class EditDocumentBean implements EditDocument {
@In EntityManager em;
@In Document document;
@In FacesMessages facesMessages;
public String update() {
em.merge(document);
facesMessages.add("Document updated");
}
}
Any message added to facesMessages is used in the very next render response phase for the
current conversation. This even works when there is no long-running conversation since Seam
preserves even temporary conversation contexts across redirects.
You can even include JSF EL expressions in a faces message summary:
facesMessages.add("Document #{document.title} was updated");
You may display the messages in the usual way, for example:
<h:messages globalOnly="true"/>
7.6. Natural conversation ids
When working with conversations that deal with persistent objects, it may be desirable to use the
natural business key of the object instead of the standard, "surrogate" conversation id:
Easy redirect to existing conversation
It can be useful to redirect to an existing conversation if the user requests the same operation
twice. Take this example: “ You are on ebay, half way through paying for an item you just won as
a Christmas present for your parents. Lets say you're sending it straight to them - you enter your
payment details but you can't remember their address. You accidentally reuse the same browser
window finding out their address. Now you need to return to the payment for the item. ”
With a natural conversation its really easy to have the user rejoin the existing conversation, and
pick up where they left off - just have them to rejoin the payForItem conversation with the itemId
as the conversation id.
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User friendly URLs
For me this consists of a navigable hierarchy (I can navigate by editing the url) and a meaningful
URL (like this Wiki uses - so don't identify things by random ids). For some applications user
friendly URLs are less important, of course.
With a natural conversations, when you are building your hotel booking system (or,
of course, whatever your app is) you can generate a URL like http://seam-hotels/
book.seam?hotel=BestWesternAntwerpen (of course, whatever parameter hotel maps to on
your domain model must be unique) and with URLRewrite easily transform this to http://seamhotels/book/BestWesternAntwerpen.
Much better!
7.7. Creating a natural conversation
Natural conversations are defined in pages.xml:
<conversation name="PlaceBid"
parameter-name="auctionId"
parameter-value="#{auction.auctionId}"/>
The first thing to note from the above definition is that the conversation has a name, in this case
PlaceBid. This name uniquely identifies this particular named conversation, and is used by the
page definition to identify a named conversation to participate in.
The next attribute, parameter-name defines the request parameter that will contain the natural
conversation id, in place of the default conversation id parameter. In this example, the parametername is auctionId. This means that instead of a conversation parameter like cid=123 appearing
in the URL for your page, it will contain auctionId=765432 instead.
The last attribute in the above configuration, parameter-value, defines an EL expression used
to evaluate the value of the natural business key to use as the conversation id. In this example,
the conversation id will be the primary key value of the auction instance currently in scope.
Next, we define which pages will participate in the named conversation. This is done by specifying
the conversation attribute for a page definition:
<page view-id="/bid.xhtml" conversation="PlaceBid" login-required="true">
<navigation from-action="#{bidAction.confirmBid}">
<rule if-outcome="success">
<redirect view-id="/auction.xhtml">
<param name="id" value="#{bidAction.bid.auction.auctionId}"/>
</redirect>
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</rule>
</navigation>
</page>
7.8. Redirecting to a natural conversation
When starting, or redirecting to, a natural conversation there are a number of options for specifying
the natural conversation name. Let's start by looking at the following page definition:
<page view-id="/auction.xhtml">
<param name="id" value="#{auctionDetail.selectedAuctionId}"/>
<navigation from-action="#{bidAction.placeBid}">
<redirect view-id="/bid.xhtml"/>
</navigation>
</page>
From here, we can see that invoking the action #{bidAction.placeBid} from our auction view
(by the way, all these examples are taken from the seamBay example in Seam), that we will be
redirected to /bid.xhtml, which, as we saw previously, is configured with the natural conversation
PlaceBid. The declaration for our action method looks like this:
@Begin(join = true)
public void placeBid()
When named conversations are specified in the <page/> element, redirection to the named
conversation occurs as part of navigation rules, after the action method has already been invoked.
This is a problem when redirecting to an existing conversation, as redirection needs to be occur
before the action method is invoked. Therefore it is necessary to specify the conversation name
when the action is invoked. One way of doing this is by using the s:conversationName tag:
<h:commandButton
id="placeBidWithAmount"
action="#{bidAction.placeBid}">
<s:conversationName value="PlaceBid"/>
</h:commandButton>
styleClass="placeBid"
Another alternative is to specify the conversationName attribute when using either s:link or
s:button:
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<s:link value="Place Bid" action="#{bidAction.placeBid}" conversationName="PlaceBid"/>
7.9. Workspace management
Workspace management is the ability to "switch" conversations in a single window. Seam
makes workspace management completely transparent at the level of the Java code. To enable
workspace management, all you need to do is:
• Provide description text for each view id (when using JSF or Seam navigation rules) or page
node (when using jPDL pageflows). This description text is displayed to the user by the
workspace switchers.
• Include one or more of the standard workspace switcher JSP or facelets fragments in your
pages. The standard fragments support workspace management via a drop down menu, a list
of conversations, or breadcrumbs.
7.9.1. Workspace management and JSF navigation
When you use JSF or Seam navigation rules, Seam switches to a conversation by restoring
the current view-id for that conversation. The descriptive text for the workspace is defined in
a file called pages.xml that Seam expects to find in the WEB-INF directory, right next to facesconfig.xml:
<pages>
<page view-id="/main.xhtml">
<description>Search hotels: #{hotelBooking.searchString}</description>
</page>
<page view-id="/hotel.xhtml">
<description>View hotel: #{hotel.name}</description>
</page>
<page view-id="/book.xhtml">
<description>Book hotel: #{hotel.name}</description>
</page>
<page view-id="/confirm.xhtml">
<description>Confirm: #{booking.description}</description>
</page>
</pages>
Note that if this file is missing, the Seam application will continue to work perfectly! The only
missing functionality will be the ability to switch workspaces.
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7.9.2. Workspace management and jPDL pageflow
When you use a jPDL pageflow definition, Seam switches to a conversation by restoring the
current jBPM process state. This is a more flexible model since it allows the same view-id to have
different descriptions depending upon the current <page> node. The description text is defined
by the <page> node:
<pageflow-definition name="shopping">
<start-state name="start">
<transition to="browse"/>
</start-state>
<page name="browse" view-id="/browse.xhtml">
<description>DVD Search: #{search.searchPattern}</description>
<transition to="browse"/>
<transition name="checkout" to="checkout"/>
</page>
<page name="checkout" view-id="/checkout.xhtml">
<description>Purchase: $#{cart.total}</description>
<transition to="checkout"/>
<transition name="complete" to="complete"/>
</page>
<page name="complete" view-id="/complete.xhtml">
<end-conversation />
</page>
</pageflow-definition>
7.9.3. The conversation switcher
Include the following fragment in your JSP or facelets page to get a drop-down menu that lets you
switch to any current conversation, or to any other page of the application:
<h:selectOneMenu value="#{switcher.conversationIdOrOutcome}">
<f:selectItem itemLabel="Find Issues" itemValue="findIssue"/>
<f:selectItem itemLabel="Create Issue" itemValue="editIssue"/>
<f:selectItems value="#{switcher.selectItems}"/>
</h:selectOneMenu>
<h:commandButton action="#{switcher.select}" value="Switch"/>
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In this example, we have a menu that includes an item for each conversation, together with two
additional items that let the user begin a new conversation.
Only conversations with a description (specified in pages.xml) will be included in the drop-down
menu.
7.9.4. The conversation list
The conversation list is very similar to the conversation switcher, except that it is displayed as
a table:
<h:dataTable value="#{conversationList}" var="entry"
rendered="#{not empty conversationList}">
<h:column>
<f:facet name="header">Workspace</f:facet>
<h:commandLink action="#{entry.select}" value="#{entry.description}"/>
<h:outputText value="[current]" rendered="#{entry.current}"/>
</h:column>
<h:column>
<f:facet name="header">Activity</f:facet>
<h:outputText value="#{entry.startDatetime}">
<f:convertDateTime type="time" pattern="hh:mm a"/>
</h:outputText>
<h:outputText value=" - "/>
<h:outputText value="#{entry.lastDatetime}">
<f:convertDateTime type="time" pattern="hh:mm a"/>
</h:outputText>
</h:column>
<h:column>
<f:facet name="header">Action</f:facet>
<h:commandButton action="#{entry.select}" value="#{msg.Switch}"/>
<h:commandButton action="#{entry.destroy}" value="#{msg.Destroy}"/>
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</h:column>
</h:dataTable>
We imagine that you will want to customize this for your own application.
Only conversations with a description will be included in the list.
Notice that the conversation list lets the user destroy workspaces.
7.9.5. Breadcrumbs
Breadcrumbs are useful in applications which use a nested conversation model. The breadcrumbs
are a list of links to conversations in the current conversation stack:
<ui:repeat value="#{conversationStack}" var="entry">
<h:outputText value=" | "/>
<h:commandLink value="#{entry.description}" action="#{entry.select}"/>
</ui:repeat
7.10. Conversational components and JSF component
bindings
Conversational components have one minor limitation: they cannot be used to hold bindings to
JSF components. (We generally prefer not to use this feature of JSF unless absolutely necessary,
since it creates a hard dependency from application logic to the view.) On a postback request,
component bindings are updated during the Restore View phase, before the Seam conversation
context has been restored.
To work around this use an event scoped component to store the component bindings and inject
it into the conversation scoped component that requires it.
@Name("grid")
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@Scope(ScopeType.EVENT)
public class Grid
{
private HtmlPanelGrid htmlPanelGrid;
// getters and setters
...
}
@Name("gridEditor")
@Scope(ScopeType.CONVERSATION)
public class GridEditor
{
@In(required=false)
private Grid grid;
...
}
Also, you can't inject a conversation scoped component into an event scoped component which
you bind a JSF control to. This includes Seam built in components like facesMessages.
Alternatively, you can access the JSF component tree through the implicit uiComponent handle.
The following example accesses getRowIndex()of the UIData component which backs the data
table during iteration, it prints the current row number:
<h:dataTable id="lineItemTable" var="lineItem" value="#{orderHome.lineItems}">
<h:column>
Row: #{uiComponent['lineItemTable'].rowIndex}
</h:column>
...
</h:dataTable>
JSF UI components are available with their client identifier in this map.
7.11. Concurrent calls to conversational components
A general discussion of concurrent calls to Seam components can be found in Section 4.1.10,
“Concurrency model”. Here we will discuss the most common situation in which you will encounter
concurrency — accessing conversational components from AJAX requests. We're going to
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discuss the options that a Ajax client library should provide to control events originating at the
client — and we'll look at the options RichFaces gives you.
Conversational components don't allow real concurrent access therefore Seam queues each
request to process them serially. This allows each request to be executed in a deterministic
fashion. However, a simple queue isn't that great — firstly, if a method is, for some reason, taking a
very long time to complete, running it over and over again whenever the client generates a request
is bad idea (potential for Denial of Service attacks), and, secondly, AJAX is often to used to provide
a quick status update to the user, so continuing to run the action after a long time isn't useful.
Therefore Seam queues the action event for a period of time (the concurrent request timeout); if
it can't process the event in time, it creates a temporary conversation and prints out a message
to the user to let them know what's going on. It's therefore very important not to flood the server
with AJAX events!
We can set a sensible default for the concurrent request timeout (in ms) in components.xml:
<core:manager concurrent-request-timeout="500" />
So far we've discussed "synchronous" AJAX requests - the client tells the server that an event has
occur, and then rerenders part of the page based on the result. This approach is great when the
AJAX request is lightweight (the methods called are simple e.g. calculating the sum of a column
of numbers). But what if we need to do a complex computation?
For heavy computation we should use a truly asynchronous (poll based) approach — the client
sends an AJAX request to the server, which causes action to be executed asynchronously on
the server (so the the response to the client is immediate); the client then polls the server for
updates. This is useful when you have a long-running action for which it is important that every
action executes (you don't want some to be dropped as duplicates, or to timeout).
How should we design our conversational AJAX application?
Well first, you need to decide whether you want to use the simpler "synchronous" request or
whether you want to add using a poll-style approach.
If you go for a "synchronous" approach, then you need to make an estimate of how long your
AJAX request will take to complete - is it much shorter than the concurrent request timeout? If not,
you probably want to alter the concurrent request timeout for this method (as discussed above).
Next you probably want a queue on the client side to prevent flooding the server with requests. If
the event occurs often (e.g. a keypress, onblur of input fields) and immediate update of the client
is not a priority you should set a request delay on the client side. When working out your request
delay, factor in that the event may also be queued on the server side.
Finally, the client library may provide an option to abort unfinished duplicate requests in favor of
the most recent. You need to be careful with this option as it can lead to flooding of the server with
requests if the server is not able to abort the unfinished request.
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Using a poll-style design requires less fine-tuning. You just mark your action method
@Asynchronous and decide on a polling interval:
int total;
// This method is called when an event occurs on the client
// It takes a really long time to execute
@Asynchronous
public void calculateTotal() {
total = someReallyComplicatedCalculation();
}
// This method is called as the result of the poll
// It's very quick to execute
public int getTotal() {
return total;
}
7.11.1. RichFaces Ajax
RichFaces Ajax is the AJAX library most commonly used with Seam, and provides all the controls
discussed above:
• eventsQueue — provide a queue in which events are placed. All events are queued and
requests are sent to the server serially. This is useful if the request can to the server can take
some time to execute (e.g. heavy computation, retrieving information from a slow source) as
the server isn't flooded.
• ignoreDupResponses — ignore the response produced by the request if a more recent 'similar'
request is already in the queue. ignoreDupResponses="true" does not cancel the the processing
of the request on the server side — just prevents unnecessary updates on the client side.
This option should be used with care with Seam's conversations as it allows multiple concurrent
requests to be made.
• requestDelay — defines the time (in ms.) that the request will be remain on the queue. If
the request has not been processed by after this time the request will be sent (regardless of
whether a response has been received) or discarded (if there is a more recent similar event
on the queue).
This option should be used with care with Seam's conversations as it allows multiple concurrent
requests to be made. You need to be sure that the delay you set (in combination with the
concurrent request timeout) is longer than the action will take to execute.
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• <a:poll reRender="total" interval="1000" /> — Polls the server, and rerenders an area
as needed
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Chapter 8.
Pageflows and business processes
JBoss jBPM is a business process management engine for any Java SE or EE environment. jBPM
lets you represent a business process or user interaction as a graph of nodes representing wait
states, decisions, tasks, web pages, etc. The graph is defined using a simple, very readable, XML
dialect called jPDL, and may be edited and visualised graphically using an eclipse plugin. jPDL
is an extensible language, and is suitable for a range of problems, from defining web application
page flow, to traditional workflow management, all the way up to orchestration of services in a
SOA environment.
Seam applications use jBPM for two different problems:
• Defining the pageflow involved in complex user interactions. A jPDL process definition defines
the page flow for a single conversation. A Seam conversation is considered to be a relatively
short-running interaction with a single user.
• Defining the overarching business process. The business process may span multiple
conversations with multiple users. Its state is persistent in the jBPM database, so it is considered
long-running. Coordination of the activities of multiple users is a much more complex problem
than scripting an interaction with a single user, so jBPM offers sophisticated facilities for task
management and dealing with multiple concurrent paths of execution.
Don't get these two things confused ! They operate at very different levels or granularity. Pageflow,
conversation and task all refer to a single interaction with a single user. A business process spans
many tasks. Futhermore, the two applications of jBPM are totally orthogonal. You can use them
together or independently or not at all.
You don't have to know jDPL to use Seam. If you're perfectly happy defining pageflow using
JSF or Seam navigation rules, and if your application is more data-driven that process-driven,
you probably don't need jBPM. But we're finding that thinking of user interaction in terms of a
well-defined graphical representation is helping us build more robust applications.
8.1. Pageflow in Seam
There are two ways to define pageflow in Seam:
• Using JSF or Seam navigation rules - the stateless navigation model
• Using jPDL - the stateful navigation model
Very simple applications will only need the stateless navigation model. Very complex applications
will use both models in different places. Each model has its strengths and weaknesses!
8.1.1. The two navigation models
The stateless model defines a mapping from a set of named, logical outcomes of an event directly
to the resulting page of the view. The navigation rules are entirely oblivious to any state held by the
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application other than what page was the source of the event. This means that your action listener
methods must sometimes make decisions about the page flow, since only they have access to
the current state of the application.
Here is an example page flow definition using JSF navigation rules:
<navigation-rule>
<from-view-id>/numberGuess.jsp</from-view-id>
<navigation-case>
<from-outcome>guess</from-outcome>
<to-view-id>/numberGuess.jsp</to-view-id>
<redirect/>
</navigation-case>
<navigation-case>
<from-outcome>win</from-outcome>
<to-view-id>/win.jsp</to-view-id>
<redirect/>
</navigation-case>
<navigation-case>
<from-outcome>lose</from-outcome>
<to-view-id>/lose.jsp</to-view-id>
<redirect/>
</navigation-case>
</navigation-rule>
Here is the same example page flow definition using Seam navigation rules:
<page view-id="/numberGuess.jsp">
<navigation>
<rule if-outcome="guess">
<redirect view-id="/numberGuess.jsp"/>
</rule>
<rule if-outcome="win">
<redirect view-id="/win.jsp"/>
</rule>
<rule if-outcome="lose">
<redirect view-id="/lose.jsp"/>
</rule>
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The two navigation models
</navigation>
</page>
If you find navigation rules overly verbose, you can return view ids directly from your action listener
methods:
public String guess() {
if (guess==randomNumber) return "/win.jsp";
if (++guessCount==maxGuesses) return "/lose.jsp";
return null;
}
Note that this results in a redirect. You can even specify parameters to be used in the redirect:
public String search() {
return "/searchResults.jsp?searchPattern=#{searchAction.searchPattern}";
}
The stateful model defines a set of transitions between a set of named, logical application states.
In this model, it is possible to express the flow of any user interaction entirely in the jPDL
pageflow definition, and write action listener methods that are completely unaware of the flow of
the interaction.
Here is an example page flow definition using jPDL:
<pageflow-definition name="numberGuess">
<start-page name="displayGuess" view-id="/numberGuess.jsp">
<redirect/>
<transition name="guess" to="evaluateGuess">
<action expression="#{numberGuess.guess}" />
</transition>
</start-page>
<decision name="evaluateGuess" expression="#{numberGuess.correctGuess}">
<transition name="true" to="win"/>
<transition name="false" to="evaluateRemainingGuesses"/>
</decision>
<decision name="evaluateRemainingGuesses" expression="#{numberGuess.lastGuess}">
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<transition name="true" to="lose"/>
<transition name="false" to="displayGuess"/>
</decision>
<page name="win" view-id="/win.jsp">
<redirect/>
<end-conversation />
</page>
<page name="lose" view-id="/lose.jsp">
<redirect/>
<end-conversation />
</page>
</pageflow-definition>
There are two things we notice immediately here:
• The JSF/Seam navigation rules are much simpler. (However, this obscures the fact that the
underlying Java code is more complex.)
• The jPDL makes the user interaction immediately understandable, without us needing to even
look at the JSP or Java code.
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Seam and the back button
In addition, the stateful model is more constrained. For each logical state (each step in the page
flow), there are a constrained set of possible transitions to other states. The stateless model is
an ad hoc model which is suitable to relatively unconstrained, freeform navigation where the user
decides where he/she wants to go next, not the application.
The stateful/stateless navigation distinction is quite similar to the traditional view of modal/
modeless interaction. Now, Seam applications are not usually modal in the simple sense of
the word - indeed, avoiding application modal behavior is one of the main reasons for having
conversations! However, Seam applications can be, and often are, modal at the level of a particular
conversation. It is well-known that modal behavior is something to avoid as much as possible; it
is very difficult to predict the order in which your users are going to want to do things! However,
there is no doubt that the stateful model has its place.
The biggest contrast between the two models is the back-button behavior.
8.1.2. Seam and the back button
When JSF or Seam navigation rules are used, Seam lets the user freely navigate via the back,
forward and refresh buttons. It is the responsibility of the application to ensure that conversational
state remains internally consistent when this occurs. Experience with the combination of web
application frameworks like Struts or WebWork - that do not support a conversational model and stateless component models like EJB stateless session beans or the Spring framework has
taught many developers that this is close to impossible to do! However, our experience is that
in the context of Seam, where there is a well-defined conversational model, backed by stateful
session beans, it is actually quite straightforward. Usually it is as simple as combining the use
of no-conversation-view-id with null checks at the beginning of action listener methods. We
consider support for freeform navigation to be almost always desirable.
In this case, the no-conversation-view-id declaration goes in pages.xml. It tells Seam to
redirect to a different page if a request originates from a page rendered during a conversation,
and that conversation no longer exists:
<page view-id="/checkout.xhtml"
no-conversation-view-id="/main.xhtml"/>
On the other hand, in the stateful model, backbuttoning is interpreted as an undefined transition
back to a previous state. Since the stateful model enforces a defined set of transitions from the
current state, back buttoning is by default disallowed in the stateful model! Seam transparently
detects the use of the back button, and blocks any attempt to perform an action from a previous,
"stale" page, and simply redirects the user to the "current" page (and displays a faces message).
Whether you consider this a feature or a limitation of the stateful model depends upon your point
of view: as an application developer, it is a feature; as a user, it might be frustrating! You can
enable backbutton navigation from a particular page node by setting back="enabled".
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<page name="checkout"
view-id="/checkout.xhtml"
back="enabled">
<redirect/>
<transition to="checkout"/>
<transition name="complete" to="complete"/>
</page>
This allows backbuttoning from the checkout state to any previous state!
Of course, we still need to define what happens if a request originates from a page rendered
during a pageflow, and the conversation with the pageflow no longer exists. In this case, the
no-conversation-view-id declaration goes into the pageflow definition:
<page name="checkout"
view-id="/checkout.xhtml"
back="enabled"
no-conversation-view-id="/main.xhtml">
<redirect/>
<transition to="checkout"/>
<transition name="complete" to="complete"/>
</page>
In practice, both navigation models have their place, and you'll quickly learn to recognize when
to prefer one model over the other.
8.2. Using jPDL pageflows
8.2.1. Installing pageflows
We need to install the Seam jBPM-related components, and tell them where to find our pageflow
definition. We can specify this Seam configuration in components.xml.
<bpm:jbpm>
<bpm:pageflow-definitions>
<value>pageflow.jpdl.xml</value>
</bpm:pageflow-definitions>
</bpm:jbpm>
The first line installs jBPM, the second points to a jPDL-based pageflow definition.
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Starting pageflows
8.2.2. Starting pageflows
We "start" a jPDL-based pageflow by specifying the name of the process definition using a @Begin,
@BeginTask or @StartTask annotation:
@Begin(pageflow="numberguess")
public void begin() { ... }
Alternatively we can start a pageflow using pages.xml:
<page>
<begin-conversation pageflow="numberguess"/>
</page>
If we are beginning the pageflow during the RENDER_RESPONSE phase—during a @Factory or
@Create method, for example—we consider ourselves to be already at the page being rendered,
and use a <start-page> node as the first node in the pageflow, as in the example above.
But if the pageflow is begun as the result of an action listener invocation, the outcome of the action
listener determines which is the first page to be rendered. In this case, we use a <start-state>
as the first node in the pageflow, and declare a transition for each possible outcome:
<pageflow-definition name="viewEditDocument">
<start-state name="start">
<transition name="documentFound" to="displayDocument"/>
<transition name="documentNotFound" to="notFound"/>
</start-state>
<page name="displayDocument" view-id="/document.jsp">
<transition name="edit" to="editDocument"/>
<transition name="done" to="main"/>
</page>
...
<page name="notFound" view-id="/404.jsp">
<end-conversation/>
</page>
</pageflow-definition>
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8.2.3. Page nodes and transitions
Each <page> node represents a state where the system is waiting for user input:
<page name="displayGuess" view-id="/numberGuess.jsp">
<redirect/>
<transition name="guess" to="evaluateGuess">
<action expression="#{numberGuess.guess}" />
</transition>
</page>
The view-id is the JSF view id. The <redirect/> element has the same effect as <redirect/>
in a JSF navigation rule: namely, a post-then-redirect behavior, to overcome problems with the
browser's refresh button. (Note that Seam propagates conversation contexts over these browser
redirects. So there is no need for a Ruby on Rails style "flash" construct in Seam!)
The transition name is the name of a JSF outcome triggered by clicking a command button or
command link in numberGuess.jsp.
<h:commandButton type="submit" value="Guess" action="guess"/>
When the transition is triggered by clicking this button, jBPM will activate the transition action
by calling the guess() method of the numberGuess component. Notice that the syntax used for
specifying actions in the jPDL is just a familiar JSF EL expression, and that the transition action
handler is just a method of a Seam component in the current Seam contexts. So we have exactly
the same event model for jBPM events that we already have for JSF events! (The One Kind of
Stuff principle.)
In the case of a null outcome (for example, a command button with no action defined), Seam will
signal the transition with no name if one exists, or else simply redisplay the page if all transitions
have names. So we could slightly simplify our example pageflow and this button:
<h:commandButton type="submit" value="Guess"/>
Would fire the following un-named transition:
<page name="displayGuess" view-id="/numberGuess.jsp">
<redirect/>
<transition to="evaluateGuess">
<action expression="#{numberGuess.guess}" />
</transition>
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Controlling the flow
</page>
It is even possible to have the button call an action method, in which case the action outcome will
determine the transition to be taken:
<h:commandButton type="submit" value="Guess" action="#{numberGuess.guess}"/>
<page name="displayGuess" view-id="/numberGuess.jsp">
<transition name="correctGuess" to="win"/>
<transition name="incorrectGuess" to="evaluateGuess"/>
</page>
However, this is considered an inferior style, since it moves responsibility for controlling the flow
out of the pageflow definition and back into the other components. It is much better to centralize
this concern in the pageflow itself.
8.2.4. Controlling the flow
Usually, we don't need the more powerful features of jPDL when defining pageflows. We do need
the <decision> node, however:
<decision name="evaluateGuess" expression="#{numberGuess.correctGuess}">
<transition name="true" to="win"/>
<transition name="false" to="evaluateRemainingGuesses"/>
</decision>
A decision is made by evaluating a JSF EL expression in the Seam contexts.
8.2.5. Ending the flow
We end the conversation using <end-conversation> or @End. (In fact, for readability, use of both
is encouraged.)
<page name="win" view-id="/win.jsp">
<redirect/>
<end-conversation/>
</page>
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Optionally, we can end a task, specify a jBPM transition name. In this case, Seam will signal
the end of the current task in the overarching business process.
<page name="win" view-id="/win.jsp">
<redirect/>
<end-task transition="success"/>
</page>
8.2.6. Pageflow composition
It is possible to compose pageflows and have one pageflow pause pause while another pageflow
executes. The <process-state> node pauses the outer pageflow, and begins execution of a
named pageflow:
<process-state name="cheat">
<sub-process name="cheat"/>
<transition to="displayGuess"/>
</process-state>
The inner flow begins executing at a <start-state> node. When it reaches an <end-state>
node, execution of the inner flow ends, and execution of the outer flow resumes with the transition
defined by the <process-state> element.
8.3. Business process management in Seam
A business process is a well-defined set of tasks that must be performed by users or software
systems according to well-defined rules about who can perform a task, and when it should
be performed. Seam's jBPM integration makes it easy to display lists of tasks to users and
let them manage their tasks. Seam also lets the application store state associated with the
business process in the BUSINESS_PROCESS context, and have that state made persistent via jBPM
variables.
A simple business process definition looks much the same as a page flow definition (One Kind
of Stuff), except that instead of <page> nodes, we have <task-node> nodes. In a long-running
business process, the wait states are where the system is waiting for some user to log in and
perform a task.
<process-definition name="todo">
<start-state name="start">
<transition to="todo"/>
</start-state>
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Using jPDL business process definitions
<task-node name="todo">
<task name="todo" description="#{todoList.description}">
<assignment actor-id="#{actor.id}"/>
</task>
<transition to="done"/>
</task-node>
<end-state name="done"/>
</process-definition>
It is perfectly possible that we might have both jPDL business process definitions and jPDL
pageflow definitions in the same project. If so, the relationship between the two is that a single
<task> in a business process corresponds to a whole pageflow <pageflow-definition>
8.4. Using jPDL business process definitions
8.4.1. Installing process definitions
We need to install jBPM, and tell it where to find the business process definitions:
<bpm:jbpm>
<bpm:process-definitions>
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<value>todo.jpdl.xml</value>
</bpm:process-definitions>
</bpm:jbpm>
As jBPM processes are persistent across application restarts, when using Seam in a production
environment you won't want to install the process definition every time the application starts.
Therefore, in a production environment, you'll need to deploy the process to jBPM outside of
Seam. In other words, only install process definitions from components.xml when developing your
application.
8.4.2. Initializing actor ids
We always need to know what user is currently logged in. jBPM "knows" users by their actor id and
group actor ids. We specify the current actor ids using the built in Seam component named actor:
@In Actor actor;
public String login() {
...
actor.setId( user.getUserName() );
actor.getGroupActorIds().addAll( user.getGroupNames() );
...
}
8.4.3. Initiating a business process
To initiate a business process instance, we use the @CreateProcess annotation:
@CreateProcess(definition="todo")
public void createTodo() { ... }
Alternatively we can initiate a business process using pages.xml:
<page>
<create-process definition="todo" />
</page>
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Task assignment
8.4.4. Task assignment
When a process reaches a task node, task instances are created. These must be assigned to
users or user groups. We can either hardcode our actor ids, or delegate to a Seam component:
<task name="todo" description="#{todoList.description}">
<assignment actor-id="#{actor.id}"/>
</task>
In this case, we have simply assigned the task to the current user. We can also assign tasks to
a pool:
<task name="todo" description="#{todoList.description}">
<assignment pooled-actors="employees"/>
</task>
8.4.5. Task lists
Several
built-in
Seam
components make it easy to display task lists.
pooledTaskInstanceList is a list of pooled tasks that users may assign to themselves:
The
<h:dataTable value="#{pooledTaskInstanceList}" var="task">
<h:column>
<f:facet name="header">Description</f:facet>
<h:outputText value="#{task.description}"/>
</h:column>
<h:column>
<s:link action="#{pooledTask.assignToCurrentActor}" value="Assign" taskInstance="#{task}"/
>
</h:column>
</h:dataTable>
Note that instead of <s:link> we could have used a plain JSF <h:commandLink>:
<h:commandLink action="#{pooledTask.assignToCurrentActor}">
<f:param name="taskId" value="#{task.id}"/>
</h:commandLink>
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The pooledTask component is a built-in component that simply assigns the task to the current
user.
The taskInstanceListForType component includes tasks of a particular type that are assigned
to the current user:
<h:dataTable value="#{taskInstanceListForType['todo']}" var="task">
<h:column>
<f:facet name="header">Description</f:facet>
<h:outputText value="#{task.description}"/>
</h:column>
<h:column>
<s:link action="#{todoList.start}" value="Start Work" taskInstance="#{task}"/>
</h:column>
</h:dataTable>
8.4.6. Performing a task
To begin work on a task, we use either @StartTask or @BeginTask on the listener method:
@StartTask
public String start() { ... }
Alternatively we can begin work on a task using pages.xml:
<page>
<start-task />
</page>
These annotations begin a special kind of conversation that has significance in terms of the
overarching business process. Work done by this conversation has access to state held in the
business process context.
If we end the conversation using @EndTask, Seam will signal the completion of the task:
@EndTask(transition="completed")
public String completed() { ... }
Alternatively we can use pages.xml:
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Performing a task
<page>
<end-task transition="completed" />
</page>
You can also use EL to specify the transition in pages.xml.
At this point, jBPM takes over and continues executing the business process definition. (In more
complex processes, several tasks might need to be completed before process execution can
resume.)
Please refer to the jBPM documentation for a more thorough overview of the sophisticated features
that jBPM provides for managing complex business processes.
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Seam and Object/Relational Mapping
Seam provides extensive support for the two most popular persistence architectures for Java:
Hibernate3, and the Java Persistence API introduced with EJB 3.0. Seam's unique statemanagement architecture allows the most sophisticated ORM integration of any web application
framework.
9.1. Introduction
Seam grew out of the frustration of the Hibernate team with the statelessness typical of the
previous generation of Java application architectures. The state management architecture of
Seam was originally designed to solve problems relating to persistence—in particular problems
associated with optimistic transaction processing. Scalable online applications always use
optimistic transactions. An atomic (database/JTA) level transaction should not span a user
interaction unless the application is designed to support only a very small number of concurrent
clients. But almost all interesting work involves first displaying data to a user, and then, slightly
later, updating the same data. So Hibernate was designed to support the idea of a persistence
context which spanned an optimistic transaction.
Unfortunately, the so-called "stateless" architectures that preceded Seam and EJB 3.0 had no
construct for representing an optimistic transaction. So, instead, these architectures provided
persistence contexts scoped to the atomic transaction. Of course, this resulted in many problems
for users, and is the cause of the number one user complaint about Hibernate: the dreaded
LazyInitializationException. What we need is a construct for representing an optimistic
transaction in the application tier.
EJB 3.0 recognizes this problem, and introduces the idea of a stateful component (a stateful
session bean) with an extended persistence context scoped to the lifetime of the component. This
is a partial solution to the problem (and is a useful construct in and of itself) however there are
two problems:
• The lifecycle of the stateful session bean must be managed manually via code in the web tier
(it turns out that this is a subtle problem and much more difficult in practice than it sounds).
• Propagation of the persistence context between stateful components in the same optimistic
transaction is possible, but tricky.
Seam solves the first problem by providing conversations, and stateful session bean components
scoped to the conversation. (Most conversations actually represent optimistic transactions in the
data layer.) This is sufficient for many simple applications (such as the Seam booking demo)
where persistence context propagation is not needed. For more complex applications, with many
loosly-interacting components in each conversation, propagation of the persistence context across
components becomes an important issue. So Seam extends the persistence context management
model of EJB 3.0, to provide conversation-scoped extended persistence contexts.
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9.2. Seam managed transactions
EJB session beans feature declarative transaction management. The EJB container is able to start
a transaction transparently when the bean is invoked, and end it when the invocation ends. If we
write a session bean method that acts as a JSF action listener, we can do all the work associated
with that action in one transaction, and be sure that it is committed or rolled back when we finish
processing the action. This is a great feature, and all that is needed by some Seam applications.
However, there is a problem with this approach. A Seam application may not perform all data
access for a request from a single method call to a session bean.
• The request might require processing by several loosly-coupled components, each of which is
called independently from the web layer. It is common to see several or even many calls per
request from the web layer to EJB components in Seam.
• Rendering of the view might require lazy fetching of associations.
The more transactions per request, the more likely we are to encounter atomicity and isolation
problems when our application is processing many concurrent requests. Certainly, all write
operations should occur in the same transaction!
Hibernate users developed the "open session in view" pattern to work around this problem. In
the Hibernate community, "open session in view" was historically even more important because
frameworks like Spring use transaction-scoped persistence contexts. So rendering the view would
cause LazyInitializationExceptions when unfetched associations were accessed.
This pattern is usually implemented as a single transaction which spans the entire request. There
are several problems with this implementation, the most serious being that we can never be sure
that a transaction is successful until we commit it—but by the time the "open session in view"
transaction is committed, the view is fully rendered, and the rendered response may already have
been flushed to the client. How can we notify the user that their transaction was unsuccessful?
Seam solves both the transaction isolation problem and the association fetching problem, while
working around the problems with "open session in view". The solution comes in two parts:
• use an extended persistence context that is scoped to the conversation, instead of to the
transaction
• use two transactions per request; the first spans the beginning of the restore view phase (some
transaction managers begin the transaction later at the beginning of the apply request vaues
phase) until the end of the invoke application phase; the second spans the render response
phase
In the next section, we'll tell you how to set up a conversation-scope persistence context. But
first we need to tell you how to enable Seam transaction management. Note that you can use
conversation-scoped persistence contexts without Seam transaction management, and there are
good reasons to use Seam transaction management even when you're not using Seam-managed
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Disabling Seam-managed transactions
persistence contexts. However, the two facilities were designed to work together, and work best
when used together.
Seam transaction management is useful even if you're using EJB 3.0 container-managed
persistence contexts. But it is especially useful if you use Seam outside a Java EE 5 environment,
or in any other case where you would use a Seam-managed persistence context.
9.2.1. Disabling Seam-managed transactions
Seam transaction management is enabled by default for all JSF requests. If you want to disable
this feature, you can do it in components.xml:
<core:init transaction-management-enabled="false"/>
<transaction:no-transaction />
9.2.2. Configuring a Seam transaction manager
Seam provides a transaction management abstraction for beginning, committing, rolling back,
and synchronizing with a transaction. By default Seam uses a JTA transaction component that
integrates with Container Managed and programmatic EJB transactions. If you are working
in a Java EE 5 environment, you should install the EJB synchronization component in
components.xml:
<transaction:ejb-transaction />
However, if you are working in a non EE 5 container, Seam will try auto detect the transaction
synchronization mechanism to use. However, if Seam is unable to detect the correct transaction
synchronization to use, you may find you need configure one of the following:
• JPA RESOURCE_LOCAL transactions with the javax.persistence.EntityTransaction
interface. EntityTransaction begins the transaction at the beginning of the apply request
values phase.
• Hibernate
managed
transactions
with
the
org.hibernate.Transaction
interface.
HibernateTransaction begins the transaction at the beginning of the apply request values
phase.
• Spring
managed
transactions
with
the
org.springframework.transaction.PlatformTransactionManager interface. The Spring
PlatformTransactionManagement manager may begin the transaction at the beginning of the
apply request values phase if the userConversationContext attribute is set.
• Explicitly disable Seam managed transactions
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Configure JPA RESOURCE_LOCAL transaction management by adding the following to your
components.xml where #{em} is the name of the persistence:managed-persistence-context
component. If your managed persistence context is named entityManager, you can opt to leave
out the entity-manager attribute. (see Seam-managed persistence contexts )
<transaction:entity-transaction entity-manager="#{em}"/>
To configure Hibernate managed transactions declare the following in your components.xml where
#{hibernateSession} is the name of the project's persistence:managed-hibernate-session
component. If your managed hibernate session is named session, you can opt to leave out the
session attribute. (see Seam-managed persistence contexts )
<transaction:hibernate-transaction session="#{hibernateSession}"/>
To explicitly disable Seam managed transactions declare the following in your components.xml:
<transaction:no-transaction />
For configuring Spring managed transactions see using Spring PlatformTransactionManagement .
9.2.3. Transaction synchronization
Transaction synchronization provides callbacks for transaction related events such as
beforeCompletion() and afterCompletion(). By default, Seam uses it's own transaction
synchronization component which requires explicit use of the Seam transaction component when
committing a transaction to ensure synchronization callbacks are correctly executed. If in a Java
EE 5 environment the <transaction:ejb-transaction/> component should be be declared
in components.xml to ensure that Seam synchronization callbacks are correctly called if the
container commits a transaction outside of Seam's knowledge.
9.3. Seam-managed persistence contexts
If you're using Seam outside of a Java EE 5 environment, you can't rely upon the container to
manage the persistence context lifecycle for you. Even if you are in an EE 5 environment, you
might have a complex application with many loosly coupled components that collaborate together
in the scope of a single conversation, and in this case you might find that propagation of the
persistence context between component is tricky and error-prone.
In either case, you'll need to use a managed persistence context (for JPA) or a managed session
(for Hibernate) in your components. A Seam-managed persistence context is just a built-in Seam
component that manages an instance of EntityManager or Session in the conversation context.
You can inject it with @In.
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with JPA
Seam-managed persistence contexts are extremely efficient in a clustered environment. Seam
is able to perform an optimization that EJB 3.0 specification does not allow containers to use
for container-managed extended persistence contexts. Seam supports transparent failover of
extended persisence contexts, without the need to replicate any persistence context state between
nodes. (We hope to fix this oversight in the next revision of the EJB spec.)
9.3.1. Using a Seam-managed persistence context with JPA
Configuring a managed persistence context is easy. In components.xml, we can write:
<persistence:managed-persistence-context name="bookingDatabase"
auto-create="true"
persistence-unit-jndi-name="java:/EntityManagerFactories/bookingData"/>
This configuration creates a conversation-scoped Seam component named bookingDatabase
that manages the lifecycle of EntityManager instances for the persistence unit
(EntityManagerFactory instance) with JNDI name java:/EntityManagerFactories/
bookingData.
Of course, you need to make sure that you have bound the EntityManagerFactory into JNDI. In
JBoss, you can do this by adding the following property setting to persistence.xml.
<property name="jboss.entity.manager.factory.jndi.name"
value="java:/EntityManagerFactories/bookingData"/>
Now we can have our EntityManager injected using:
@In EntityManager bookingDatabase;
If you are using EJB3 and mark your class or method @TransactionAttribute(REQUIRES_NEW)
then the transaction and persistence context shouldn't be propagated to method calls on this
object. However as the Seam-managed persistence context is propagated to any component
within the conversation, it will be propagated to methods marked REQUIRES_NEW. Therefore,
if you mark a method REQUIRES_NEW then you should access the entity manager using
@PersistenceContext.
9.3.2. Using a Seam-managed Hibernate session
Seam-managed Hibernate sessions are similar. In components.xml:
<persistence:hibernate-session-factory name="hibernateSessionFactory"/>
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<persistence:managed-hibernate-session name="bookingDatabase"
auto-create="true"
session-factory-jndi-name="java:/bookingSessionFactory"/>
Where java:/bookingSessionFactory is the name of the session factory specified in
hibernate.cfg.xml.
<session-factory name="java:/bookingSessionFactory">
<property name="transaction.flush_before_completion">true</property>
<property name="connection.release_mode">after_statement</property>
<property
property>
<property
property>
<property name="connection.datasource">java:/bookingDatasource</property>
...
</session-factory>
Note
that
Seam
does
not
flush
the
session, so you should always enable
hibernate.transaction.flush_before_completion to ensure that the session is automatically
flushed before the JTA transaction commits.
We can now have a managed Hibernate Session injected into our JavaBean components using
the following code:
@In Session bookingDatabase;
9.3.3. Seam-managed persistence contexts and atomic
conversations
Persistence contexts scoped to the conversation allows you to program optimistic transactions
that span multiple requests to the server without the need to use the merge() operation , without
the need to re-load data at the beginning of each request, and without the need to wrestle with
the LazyInitializationException or NonUniqueObjectException.
As with any optimistic transaction management, transaction isolation and consistency can be
achieved via use of optimistic locking. Fortunately, both Hibernate and EJB 3.0 make it very easy
to use optimistic locking, by providing the @Version annotation.
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Seam-managed persistence contexts and
atomic conversations
By default, the persistence context is flushed (synchronized with the database) at the end of
each transaction. This is sometimes the desired behavior. But very often, we would prefer
that all changes are held in memory and only written to the database when the conversation
ends successfully. This allows for truly atomic conversations. As the result of a truly stupid
and shortsighted decision by certain non-JBoss, non-Sun and non-Sybase members of the EJB
3.0 expert group, there is currently no simple, usable and portable way to implement atomic
conversations using EJB 3.0 persistence. However, Hibernate provides this feature as a vendor
extension to the FlushModeTypes defined by the specification, and it is our expectation that other
vendors will soon provide a similar extension.
Seam lets you specify FlushModeType.MANUAL when beginning a conversation. Currently, this
works only when Hibernate is the underlying persistence provider, but we plan to support other
equivalent vendor extensions.
@In EntityManager em; //a Seam-managed persistence context
@Begin(flushMode=MANUAL)
public void beginClaimWizard() {
claim = em.find(Claim.class, claimId);
}
Now, the claim object remains managed by the persistence context for the rest ot the
conversation. We can make changes to the claim:
public void addPartyToClaim() {
Party party = ....;
claim.addParty(party);
}
But these changes will not be flushed to the database until we explicitly force the flush to occur:
@End
public void commitClaim() {
em.flush();
}
Of course, you could set the flushMode to MANUAL from pages.xml, for example in a navigation
rule:
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<begin-conversation flush-mode="MANUAL" />
9.4. Using the JPA "delegate"
The EntityManager interface lets you access a vendor-specific API via the getDelegate()
method. Naturally, the most interesting vendor is Hibernate, and the most powerful delegate
interface is org.hibernate.Session. You'd be nuts to use anything else. Trust me, I'm not biased
at all. If you must use a different JPA provider see Using Alternate JPA Providers.
But regardless of whether you're using Hibernate (genius!) or something else (masochist, or just
not very bright), you'll almost certainly want to use the delegate in your Seam components from
time to time. One approach would be the following:
@In EntityManager entityManager;
@Create
public void init() {
( (Session) entityManager.getDelegate() ).enableFilter("currentVersions");
}
But typecasts are unquestionably the ugliest syntax in the Java language, so most people avoid
them whenever possible. Here's a different way to get at the delegate. First, add the following
line to components.xml:
<factory name="session"
scope="STATELESS"
auto-create="true"
value="#{entityManager.delegate}"/>
Now we can inject the session directly:
@In Session session;
@Create
public void init() {
session.enableFilter("currentVersions");
}
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Using EL in EJB-QL/HQL
9.5. Using EL in EJB-QL/HQL
Seam proxies the EntityManager or Session object whenever you use a Seammanaged persistence context or inject a container managed persistence context using
@PersistenceContext. This lets you use EL expressions in your query strings, safely and
efficiently. For example, this:
User user = em.createQuery("from User where username=#{user.username}")
.getSingleResult();
is equivalent to:
User user = em.createQuery("from User where username=:username")
.setParameter("username", user.getUsername())
.getSingleResult();
Of course, you should never, ever write it like this:
User user = em.createQuery("from User where username=" + user.getUsername()) //BAD!
.getSingleResult();
(It is inefficient and vulnerable to SQL injection attacks.)
9.6. Using Hibernate filters
The coolest, and most unique, feature of Hibernate is filters. Filters let you provide a restricted view
of the data in the database. You can find out more about filters in the Hibernate documentation.
But we thought we'd mention an easy way to incorporate filters into a Seam application, one that
works especially well with the Seam Application Framework.
Seam-managed persistence contexts may have a list of filters defined, which will be enabled
whenever an EntityManager or Hibernate Session is first created. (Of course, they may only be
used when Hibernate is the underlying persistence provider.)
<persistence:filter name="regionFilter">
<persistence:name>region</persistence:name>
<persistence:parameters>
<key>regionCode</key>
<value>#{region.code}</value>
</persistence:parameters>
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</persistence:filter>
<persistence:filter name="currentFilter">
<persistence:name>current</persistence:name>
<persistence:parameters>
<key>date</key>
<value>#{currentDate}</value>
</persistence:parameters>
</persistence:filter>
<persistence:managed-persistence-context name="personDatabase"
persistence-unit-jndi-name="java:/EntityManagerFactories/personDatabase">
<core:filters>
<value>#{regionFilter}</value>
<value>#{currentFilter}</value>
</core:filters>
</persistence:managed-persistence-context>
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Chapter 10.
JSF form validation in Seam
In plain JSF, validation is defined in the view:
<h:form>
<h:messages/>
<div>
Country:
<h:inputText value="#{location.country}" required="true">
<my:validateCountry/>
</h:inputText>
</div>
<div>
Zip code:
<h:inputText value="#{location.zip}" required="true">
<my:validateZip/>
</h:inputText>
</div>
<h:commandButton/>
</h:form>
In practice, this approach usually violates DRY, since most "validation" actually enforces
constraints that are part of the data model, and exist all the way down to the database schema
definition. Seam provides support for model-based constraints defined using Hibernate Validator.
Let's start by defining our constraints, on our Location class:
public class Location {
private String country;
private String zip;
@NotNull
@Length(max=30)
public String getCountry() { return country; }
public void setCountry(String c) { country = c; }
@NotNull
@Length(max=6)
@Pattern("^\d*$")
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public String getZip() { return zip; }
public void setZip(String z) { zip = z; }
}
Well, that's a decent first cut, but in practice it might be more elegant to use custom constraints
instead of the ones built into Hibernate Validator:
public class Location {
private String country;
private String zip;
@NotNull
@Country
public String getCountry() { return country; }
public void setCountry(String c) { country = c; }
@NotNull
@ZipCode
public String getZip() { return zip; }
public void setZip(String z) { zip = z; }
}
Whichever route we take, we no longer need to specify the type of validation to be used in the
JSF page. Instead, we can use <s:validate> to validate against the constraint defined on the
model object.
<h:form>
<h:messages/>
<div>
Country:
<h:inputText value="#{location.country}" required="true">
<s:validate/>
</h:inputText>
</div>
<div>
Zip code:
<h:inputText value="#{location.zip}" required="true">
<s:validate/>
</h:inputText>
</div>
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<h:commandButton/>
</h:form>
Note: specifying @NotNull on the model does not eliminate the requirement for required="true"
to appear on the control! This is due to a limitation of the JSF validation architecture.
This approach defines constraints on the model, and presents constraint violations in the view—a
significantly better design.
However, it is not much less verbose than what we started with, so let's try <s:validateAll>:
<h:form>
<h:messages/>
<s:validateAll>
<div>
Country:
<h:inputText value="#{location.country}" required="true"/>
</div>
<div>
Zip code:
<h:inputText value="#{location.zip}" required="true"/>
</div>
<h:commandButton/>
</s:validateAll>
</h:form>
This tag simply adds an <s:validate> to every input in the form. For a large form, it can save
a lot of typing!
Now we need to do something about displaying feedback to the user when validation fails.
Currently we are displaying all messages at the top of the form. What we would really like to do is
display the message next to the field with the error (this is possible in plain JSF), highlight the field
and label (this is not possible) and, for good measure, display some image next to the field (also
not possible). We also want to display a little colored asterisk next to the label for each required
form field.
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That's quite a lot of functionality we need for each field of our form. We wouldn't want to have to
specify higlighting and the layout of the image, message and input field for every field on the form.
So, instead, we'll specify the common layout in a facelets template:
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:s="http://jboss.com/products/seam/taglib">
<div>
<s:label styleClass="#{invalid?'error':''}">
<ui:insert name="label"/>
<s:span styleClass="required" rendered="#{required}">*</s:span>
</s:label>
<span class="#{invalid?'error':''}">
<h:graphicImage value="/img/error.gif" rendered="#{invalid}"/>
<s:validateAll>
<ui:insert/>
</s:validateAll>
</span>
<s:message styleClass="error"/>
</div>
</ui:composition>
We can include this template for each of our form fields using <s:decorate>.
<h:form>
<h:messages globalOnly="true"/>
<s:decorate template="edit.xhtml">
<ui:define name="label">Country:</ui:define>
<h:inputText value="#{location.country}" required="true"/>
</s:decorate>
<s:decorate template="edit.xhtml">
196
<ui:define name="label">Zip code:</ui:define>
<h:inputText value="#{location.zip}" required="true"/>
</s:decorate>
<h:commandButton/>
</h:form>
Finally, we can use RichFaces Ajax to display validation messages as the user is navigating
around the form:
<h:form>
<h:messages globalOnly="true"/>
<s:decorate id="countryDecoration" template="edit.xhtml">
<ui:define name="label">Country:</ui:define>
<h:inputText value="#{location.country}" required="true">
<a:support event="onblur" reRender="countryDecoration" bypassUpdates="true"/>
</h:inputText>
</s:decorate>
<s:decorate id="zipDecoration" template="edit.xhtml">
<ui:define name="label">Zip code:</ui:define>
<h:inputText value="#{location.zip}" required="true">
<a:support event="onblur" reRender="zipDecoration" bypassUpdates="true"/>
</h:inputText>
</s:decorate>
<h:commandButton/>
</h:form>
It's better style to define explicit ids for important controls on the page, especially if you want to
do automated testing for the UI, using some toolkit like Selenium. If you don't provide explicit ids,
JSF will generate them, but the generated values will change if you change anything on the page.
<h:form id="form">
<h:messages globalOnly="true"/>
<s:decorate id="countryDecoration" template="edit.xhtml">
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<ui:define name="label">Country:</ui:define>
<h:inputText id="country" value="#{location.country}" required="true">
<a:support event="onblur" reRender="countryDecoration" bypassUpdates="true"/>
</h:inputText>
</s:decorate>
<s:decorate id="zipDecoration" template="edit.xhtml">
<ui:define name="label">Zip code:</ui:define>
<h:inputText id="zip" value="#{location.zip}" required="true">
<a:support event="onblur" reRender="zipDecoration" bypassUpdates="true"/>
</h:inputText>
</s:decorate>
<h:commandButton/>
</h:form>
And what if you want to specify a different message to be displayed when validation fails? You
can use the Seam message bundle (and all it's goodies like el expressions inside the message,
and per-view message bundles) with the Hibernate Validator:
public class Location {
private String name;
private String zip;
// Getters and setters for name
@NotNull
@Length(max=6)
@ZipCode(message="#{messages['location.zipCode.invalid']}")
public String getZip() { return zip; }
public void setZip(String z) { zip = z; }
}
location.zipCode.invalid = The zip code is not valid for #{location.name}
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Chapter 11.
Groovy integration
One aspect of JBoss Seam is its RAD (Rapid Application Development) capability. While not
synonymous with RAD, one interesting tool in this space is dynamic languages. Until recently,
choosing a dynamic language was required choosing a completely different development platform
(a development platform with a set of APIs and a runtime so great that you would no longer want to
use you old legacy Java [sic] APIs anymore, which would be lucky because you would be forced to
use those proprietary APIs anyway). Dynamic languages built on top of the Java Virtual Machine,
and Groovy [http://groovy.codehaus.org] in particular broke this approach in silos.
JBoss Seam now unites the dynamic language world with the Java EE world by seamlessly
integrating both static and dynamic languages. JBoss Seam lets the application developer use
the best tool for the task, without context switching. Writing dynamic Seam components is exactly
like writing regular Seam components. You use the same annotations, the same APIs, the same
everything.
11.1. Groovy introduction
Groovy is an agile dynamic language based on the Java language but with additional features
inspired by Python, Ruby and Smalltalk. The strengths of Groovy are twofold:
• Java syntax is supported in Groovy: Java code is Groovy code, making the learning curve very
smooth
• Groovy objects are Java objects, and Groovy classes are Java classes: Groovy integrates
smoothly with existing Java libraries and frameworks.
TODO: write a quick overview of the Groovy syntax add-on
11.2. Writing Seam applications in Groovy
There is not much to say about it. Since a Groovy object is a Java object, you can virtually write
any Seam component, or any class for what it worth, in Groovy and deploy it. You can also mix
Groovy classes and Java classes in the same application.
11.2.1. Writing Groovy components
As you should have noticed by now, Seam uses annotations heavily. Be sure to use Groovy 1.1 or
above for annotation support. Here are some example of groovy code used in a Seam application.
11.2.1.1. Entity
@Entity
@Name("hotel")
class Hotel implements Serializable
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{
@Id @GeneratedValue
Long id
@Length(max=50) @NotNull
String name
@Length(max=100) @NotNull
String address
@Length(max=40) @NotNull
String city
@Length(min=2, max=10) @NotNull
String state
@Length(min=4, max=6) @NotNull
String zip
@Length(min=2, max=40) @NotNull
String country
@Column(precision=6, scale=2)
BigDecimal price
@Override
String toString()
{
return "Hotel(${name},${address},${city},${zip})"
}
}
Groovy natively support the notion of properties (getter/setter), so there is no need to explicitly
write verbose getters and setters: in the previous example, the hotel class can be accessed from
Java as hotel.getCity(), the getters and setters being generated by the Groovy compiler. This
type of syntactic sugar makes the entity code very concise.
11.2.1.2. Seam component
Writing Seam components in Groovy is in no way different than in Java: annotations are used to
mark the class as a Seam component.
@Scope(ScopeType.SESSION)
@Name("bookingList")
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seam-gen
class BookingListAction implements Serializable
{
@In EntityManager em
@In User user
@DataModel List<Booking> bookings
@DataModelSelection Booking booking
@Logger Log log
@Factory public void getBookings()
{
bookings = em.createQuery('''
select b from Booking b
where b.user.username = :username
order by b.checkinDate''')
.setParameter("username", user.username)
.getResultList()
}
public void cancel()
{
log.info("Cancel booking: #{bookingList.booking.id} for #{user.username}")
Booking cancelled = em.find(Booking.class, booking.id)
if (cancelled != null) em.remove( cancelled )
getBookings()
FacesMessages.instance().add("Booking cancelled for confirmation number
#{bookingList.booking.id}", new Object[0])
}
}
11.2.2. seam-gen
Seam gen has a transparent integration with Groovy. You can write Groovy code in seam-gen
backed projects without any additional infrastructure requirement. When writing a Groovy entity,
simply place your .groovy files in src/model. Unsurprisingly, when writing an action, simply place
your .groovy files in src/action.
11.3. Deployment
Deploying Groovy classes is very much like deploying Java classes (surprisingly, no need to
write nor comply with a 3-letter composite specification to support a multi-language component
framework).
Beyond standard deployments, JBoss Seam has the ability, at development time, to redeploy
JavaBeans Seam component classes without having to restart the application, saving a lot of time
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in the development / test cycle. The same support is provided for GroovyBeans Seam components
when the .groovy files are deployed.
11.3.1. Deploying Groovy code
A Groovy class is a Java class, with a bytecode representation just like a Java class. To deploy,
a Groovy entity, a Groovy Session bean or a Groovy Seam component, a compilation step is
necessary. A common approach is to use the groovyc ant task. Once compiles, a Groovy class
is in no way different than a Java class and the application server will treat them equally. Note
that this allow a seamless mix of Groovy and Java code.
11.3.2. Native .groovy file deployment at development time
JBoss Seam natively supports the deployment of .groovy files (ie without compilation) in
incremental hotdeployment mode (development only). This enables a very fast edit/test cycle. To
set up .groovy deployments, follow the configuration at Section 2.8, “Seam and incremental hot
deployment” and deploy your Groovy code (.groovy files) into the WEB-INF/dev directory. The
GroovyBean components will be picked up incrementally with no need to restart the application
(and obviously not the application server either).
Be aware that the native .groovy file deployment suffers the same limitations as the regular Seam
hotdeployment:
• The components must be JavaBeans or GroovyBeans. They cannot be EJB3 bean
• Entities cannot be hotdeployed
• The hot-deployable components will not be visible to any classes deployed outside of WEB-INF/
dev
• Seam debug mode must be enabled
11.3.3. seam-gen
Seam-gen transparently supports Groovy files deployment and compilation. This includes the
native .groovy file deployment in development mode (compilation-less). If you create a seam-gen
project of type WAR, Java and Groovy classes in src/action will automatically be candidate for
the incremental hot deployment. If you are in production mode, the Groovy files will simply be
compiled before deployment.
You will find a live example of the Booking demo written completely in Groovy and supporting
incremental hot deployment in examples/groovybooking.
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Chapter 12.
The Seam Application Framework
Seam makes it really easy to create applications by writing plain Java classes with annotations,
which don't need to extend any special interfaces or superclasses. But we can simplify some
common programming tasks even further, by providing a set of pre-built components which can
be re-used either by configuration in components.xml (for very simple cases) or extension.
The Seam Application Framework can reduce the amount of code you need to write when doing
basic database access in a web application, using either Hibernate or JPA.
We should emphasize that the framework is extremely simple, just a handful of simple classes
that are easy to understand and extend. The "magic" is in Seam itself—the same magic you use
when creating any Seam application even without using this framework.
12.1. Introduction
The components provided by the Seam application framework may be used in one of two
different approaches. The first way is to install and configure an instance of the component
in components.xml, just like we have done with other kinds of built-in Seam components. For
example, the following fragment from components.xml installs a component which can perform
basic CRUD operations for a Person entity:
<framework:entity-home name="personHome"
entity-class="eg.Person"
entity-manager="#{personDatabase}">
<framework:id>#{param.personId}</framework:id>
</framework:entity-home>
If that looks a bit too much like "programming in XML" for your taste, you can use extension instead:
@Name("personHome")
public class PersonHome extends EntityHome<Person> {
@In EntityManager personDatabase;
public EntityManager getEntityManager() {
return personDatabase;
}
}
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The second approach has one huge advantage: you can easily add extra functionality, and
override the built-in functionality (the framework classes were carefully designed for extension
and customization).
A second advantage is that your classes may be EJB stateful session beans, if you like. (They
do not have to be, they can be plain JavaBean components if you prefer.) If you are using JBoss
AS, you'll need 4.2.2.GA or later:
@Stateful
@Name("personHome")
public class PersonHome extends EntityHome<Person> implements LocalPersonHome {
}
You can also make your classes stateless session beans. In this case you must use injection to
provide the persistence context, even if it is called entityManager:
@Stateless
@Name("personHome")
public class PersonHome extends EntityHome<Person> implements LocalPersonHome {
@In EntityManager entityManager;
public EntityManager getPersistenceContext() {
entityManager;
}
}
At this time, the Seam Application Framework provides four main built-in components:
EntityHome and HibernateEntityHome for CRUD, along with EntityQuery and
HibernateEntityQuery for queries.
The Home and Query components are written so that they can function with a scope of session,
event or conversation. Which scope you use depends upon the state model you wish to use in
your application.
The Seam Application Framework only works with Seam-managed persistence contexts. By
default, the components will look for a persistence context named entityManager.
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Home objects
12.2. Home objects
A Home object provides persistence operations for a particular entity class. Suppose we have our
trusty Person class:
@Entity
public class Person {
@Id private Long id;
private String firstName;
private String lastName;
private Country nationality;
//getters and setters...
}
We can define a personHome component either via configuration:
<framework:entity-home name="personHome" entity-class="eg.Person" />
Or via extension:
@Name("personHome")
public class PersonHome extends EntityHome<Person> {}
A Home object provides the following operations: persist(), remove(), update() and
getInstance(). Before you can call the remove(), or update() operations, you must first set the
identifier of the object you are interested in, using the setId() method.
We can use a Home directly from a JSF page, for example:
<h1>Create Person</h1>
<h:form>
<div>First name: <h:inputText value="#{personHome.instance.firstName}"/></div>
<div>Last name: <h:inputText value="#{personHome.instance.lastName}"/></div>
<div>
<h:commandButton value="Create Person" action="#{personHome.persist}"/>
</div>
</h:form>
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Usually, it is much nicer to be able to refer to the Person merely as person, so let's make that
possible by adding a line to components.xml:
<factory name="person"
value="#{personHome.instance}"/>
<framework:entity-home name="personHome"
entity-class="eg.Person" />
(If we are using configuration.) Or by adding a @Factory method to PersonHome:
@Name("personHome")
public class PersonHome extends EntityHome<Person> {
@Factory("person")
public Person initPerson() { return getInstance(); }
}
(If we are using extension.) This change simplifies our JSF page to the following:
<h1>Create Person</h1>
<h:form>
<div>First name: <h:inputText value="#{person.firstName}"/></div>
<div>Last name: <h:inputText value="#{person.lastName}"/></div>
<div>
<h:commandButton value="Create Person" action="#{personHome.persist}"/>
</div>
</h:form>
Well, that lets us create new Person entries. Yes, that is all the code that is required! Now, if we
want to be able to display, update and delete pre-existing Person entries in the database, we
need to be able to pass the entry identifier to the PersonHome. Page parameters are a great way
to do that:
<pages>
<page view-id="/editPerson.jsp">
<param name="personId" value="#{personHome.id}"/>
</page>
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Home objects
</pages>
Now we can add the extra operations to our JSF page:
<h1>
<h:outputText rendered="#{!personHome.managed}" value="Create Person"/>
<h:outputText rendered="#{personHome.managed}" value="Edit Person"/>
</h1>
<h:form>
<div>First name: <h:inputText value="#{person.firstName}"/></div>
<div>Last name: <h:inputText value="#{person.lastName}"/></div>
<div>
<h:commandButton value="Create Person" action="#{personHome.persist}"
rendered="#{!personHome.managed}"/>
<h:commandButton value="Update Person" action="#{personHome.update}"
rendered="#{personHome.managed}"/>
<h:commandButton value="Delete Person" action="#{personHome.remove}"
rendered="#{personHome.managed}"/>
</div>
</h:form>
When we link to the page with no request parameters, the page will be displayed as a "Create
Person" page. When we provide a value for the personId request parameter, it will be an "Edit
Person" page.
Suppose we need to create Person entries with their nationality initialized. We can do that easily,
via configuration:
<factory name="person"
value="#{personHome.instance}"/>
<framework:entity-home name="personHome"
entity-class="eg.Person"
new-instance="#{newPerson}"/>
<component name="newPerson"
class="eg.Person">
<property name="nationality">#{country}</property>
</component>
Or by extension:
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@Name("personHome")
public class PersonHome extends EntityHome<Person> {
@In Country country;
@Factory("person")
public Person initPerson() { return getInstance(); }
protected Person createInstance() {
return new Person(country);
}
}
Of course, the Country could be an object managed by another Home object, for example,
CountryHome.
To add more sophisticated operations (association management, etc), we can just add methods
to PersonHome.
@Name("personHome")
public class PersonHome extends EntityHome<Person> {
@In Country country;
@Factory("person")
public Person initPerson() { return getInstance(); }
protected Person createInstance() {
return new Person(country);
}
public void migrate()
{
getInstance().setCountry(country);
update();
}
}
The Home object raises an org.jboss.seam.afterTransactionSuccess event when a
transaction succeeds (a call to persist(), update() or remove() succeeds). By observing this
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Home objects
event we can refresh our queries when the underlying entities are changed. If we only want to
refresh certain queries when a particular entity is persited, updated or removed we can observe
the org.jboss.seam.afterTransactionSuccess.<name> event (where <name> is the name of
the entity).
The Home object automatically displays faces messages when an operation is successful. To
customize these messages we can, again, use configuration:
<factory name="person"
value="#{personHome.instance}"/>
<framework:entity-home name="personHome"
entity-class="eg.Person"
new-instance="#{newPerson}">
<framework:created-message>New person #{person.firstName} #{person.lastName} created</
framework:created-message>
<framework:deleted-message>Person #{person.firstName} #{person.lastName} deleted</
framework:deleted-message>
<framework:updated-message>Person #{person.firstName} #{person.lastName} updated</
framework:updated-message>
</framework:entity-home>
<component name="newPerson"
class="eg.Person">
<property name="nationality">#{country}</property>
</component>
Or extension:
@Name("personHome")
public class PersonHome extends EntityHome<Person> {
@In Country country;
@Factory("person")
public Person initPerson() { return getInstance(); }
protected Person createInstance() {
return new Person(country);
}
protected String getCreatedMessage() { return "New person #{person.firstName}
#{person.lastName} created"; }
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protected String getUpdatedMessage() { return "Person #{person.firstName}
#{person.lastName} updated"; }
protected String getDeletedMessage() { return "Person #{person.firstName}
#{person.lastName} deleted"; }
}
But the best way to specify the messages is to put them in a resource bundle known to Seam (the
bundle named messages, by default).
Person_created=New person #{person.firstName} #{person.lastName} created
Person_deleted=Person #{person.firstName} #{person.lastName} deleted
Person_updated=Person #{person.firstName} #{person.lastName} updated
This enables internationalization, and keeps your code and configuration clean of presentation
concerns.
The final step is to add validation functionality to the page, using <s:validateAll> and
<s:decorate>, but I'll leave that for you to figure out.
12.3. Query objects
If we need a list of all Person instance in the database, we can use a Query object. For example:
<framework:entity-query name="people"
ejbql="select p from Person p"/>
We can use it from a JSF page:
<h1>List of people</h1>
<h:dataTable value="#{people.resultList}" var="person">
<h:column>
<s:link view="/editPerson.jsp" value="#{person.firstName} #{person.lastName}">
<f:param name="personId" value="#{person.id}"/>
</s:link>
</h:column>
</h:dataTable>
We probably need to support pagination:
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Query objects
<framework:entity-query name="people"
ejbql="select p from Person p"
order="lastName"
max-results="20"/>
We'll use a page parameter to determine the page to display:
<pages>
<page view-id="/searchPerson.jsp">
<param name="firstResult" value="#{people.firstResult}"/>
</page>
</pages>
The JSF code for a pagination control is a bit verbose, but manageable:
<h1>Search for people</h1>
<h:dataTable value="#{people.resultList}" var="person">
<h:column>
<s:link view="/editPerson.jsp" value="#{person.firstName} #{person.lastName}">
<f:param name="personId" value="#{person.id}"/>
</s:link>
</h:column>
</h:dataTable>
<s:link view="/search.xhtml" rendered="#{people.previousExists}" value="First Page">
<f:param name="firstResult" value="0"/>
</s:link>
<s:link view="/search.xhtml" rendered="#{people.previousExists}" value="Previous Page">
<f:param name="firstResult" value="#{people.previousFirstResult}"/>
</s:link>
<s:link view="/search.xhtml" rendered="#{people.nextExists}" value="Next Page">
<f:param name="firstResult" value="#{people.nextFirstResult}"/>
</s:link>
<s:link view="/search.xhtml" rendered="#{people.nextExists}" value="Last Page">
<f:param name="firstResult" value="#{people.lastFirstResult}"/>
</s:link>
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Real search screens let the user enter a bunch of optional search criteria to narrow the list of
results returned. The Query object lets you specify optional "restrictions" to support this important
usecase:
<component name="examplePerson" class="Person"/>
<framework:entity-query name="people"
ejbql="select p from Person p"
order="lastName"
max-results="20">
<framework:restrictions>
<value>lower(firstName) like lower( concat(#{examplePerson.firstName},'%') )</value>
<value>lower(lastName) like lower( concat(#{examplePerson.lastName},'%') )</value>
</framework:restrictions>
</framework:entity-query>
Notice the use of an "example" object.
<h1>Search for people</h1>
<h:form>
<div>First name: <h:inputText value="#{examplePerson.firstName}"/></div>
<div>Last name: <h:inputText value="#{examplePerson.lastName}"/></div>
<div><h:commandButton value="Search" action="/search.jsp"/></div>
</h:form>
<h:dataTable value="#{people.resultList}" var="person">
<h:column>
<s:link view="/editPerson.jsp" value="#{person.firstName} #{person.lastName}">
<f:param name="personId" value="#{person.id}"/>
</s:link>
</h:column>
</h:dataTable>
To
refresh
the
query
when
the
underlying
org.jboss.seam.afterTransactionSuccess event:
entities
<event type="org.jboss.seam.afterTransactionSuccess">
<action execute="#{people.refresh}" />
</event>
212
change
we
observe
the
Controller objects
Or, to just refresh the query when the person entity is persisted, updated or removed through
PersonHome:
<event type="org.jboss.seam.afterTransactionSuccess.Person">
<action execute="#{people.refresh}" />
</event>
Unfortunately Query objects don't work well with join fetch queries - the use of pagination with
these queries is not recomended, and you'll have to implement your own method of calculating
the total number of results (by overriding getCountEjbql().
The examples in this section have all shown reuse by configuration. However, reuse by extension
is equally possible for Query objects.
12.4. Controller objects
A
totally
optional part of the Seam Application Framework is the class
Controller and its subclasses EntityController HibernateEntityController and
BusinessProcessController. These classes provide nothing more than some convenience
methods for access to commonly used built-in components and methods of built-in components.
They help save a few keystrokes (characters can add up!) and provide a great launchpad for new
users to explore the rich functionality built in to Seam.
For example, here is what RegisterAction from the Seam registration example would look like:
@Stateless
@Name("register")
public class RegisterAction extends EntityController implements Register
{
@In private User user;
public String register()
{
List existing = createQuery("select u.username from User u where u.username=:username")
.setParameter("username", user.getUsername())
.getResultList();
if ( existing.size()==0 )
{
persist(user);
info("Registered new user #{user.username}");
return "/registered.jspx";
}
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else
{
addFacesMessage("User #{user.username} already exists");
return null;
}
}
}
As you can see, its not an earthshattering improvement...
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Chapter 13.
Seam and JBoss Rules
Seam makes it easy to call JBoss Rules (Drools) rulebases from Seam components or jBPM
process definitions.
13.1. Installing rules
The first step is to make an instance of org.drools.RuleBase available in a Seam context
variable. For testing purposes, Seam provides a built-in component that compiles a static set of
rules from the classpath. You can install this component via components.xml:
<drools:rule-base name="policyPricingRules">
<drools:rule-files>
<value>policyPricingRules.drl</value>
</drools:rule-files>
</drools:rule-base>
This component compiles rules from a set of .drl files and caches an instance of
org.drools.RuleBase in the Seam APPLICATION context. Note that it is quite likely that you will
need to install multiple rule bases in a rule-driven application.
If you want to use a Drools DSL, you alse need to specify the DSL definition:
<drools:rule-base name="policyPricingRules" dsl-file="policyPricing.dsl">
<drools:rule-files>
<value>policyPricingRules.drl</value>
</drools:rule-files>
</drools:rule-base>
In most rules-driven applications, rules need to be dynamically deployable, so a production
application will want to use a Drools RuleAgent to manage the RuleBase. The RuleAgent can
connect to a Drools rule server (BRMS) or hot deploy rules packages from a local file repository.
The RulesAgent-managed RuleBase is also configurable in components.xml:
<drools:rule-agent name="insuranceRules"
configurationFile="/WEB-INF/deployedrules.properties" />
The properties file contains properties specific to the RulesAgent. Here is an example
configuration file from the Drools example distribution.
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Chapter 13. Seam and JBoss Rules
newInstance=true
url=http://localhost:8080/drools-jbrms/org.drools.brms.JBRMS/package/org.acme.insurance/
fmeyer
localCacheDir=/Users/fernandomeyer/projects/jbossrules/drools-examples/drools-examplesbrms/cache
poll=30
name=insuranceconfig
It is also possible to configure the options on the component directly, bypassing the configuration
file.
<drools:rule-agent name="insuranceRules"
url="http://localhost:8080/drools-jbrms/org.drools.brms.JBRMS/package/org.acme.insurance/
fmeyer"
local-cache-dir="/Users/fernandomeyer/projects/jbossrules/drools-examples/droolsexamples-brms/cache"
poll="30"
configuration-name="insuranceconfig" />
Next, we need to make an instance of org.drools.WorkingMemory available to each
conversation. (Each WorkingMemory accumulates facts relating to the current conversation.)
<drools:managed-working-memory name="policyPricingWorkingMemory" auto-create="true"
rule-base="#{policyPricingRules}"/>
Notice that we gave the policyPricingWorkingMemory a reference back to our rule base via the
ruleBase configuration property.
13.2. Using rules from a Seam component
We can now inject our WorkingMemory into any Seam component, assert facts, and fire rules:
@In WorkingMemory policyPricingWorkingMemory;
@In Policy policy;
@In Customer customer;
public void pricePolicy() throws FactException
{
policyPricingWorkingMemory.assertObject(policy);
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Using rules from a jBPM process definition
policyPricingWorkingMemory.assertObject(customer);
policyPricingWorkingMemory.fireAllRules();
}
13.3. Using rules from a jBPM process definition
You can even allow a rule base to act as a jBPM action handler, decision handler, or assignment
handler—in either a pageflow or business process definition.
<decision name="approval">
<handler class="org.jboss.seam.drools.DroolsDecisionHandler">
<workingMemoryName>orderApprovalRulesWorkingMemory</workingMemoryName>
<assertObjects>
<element>#{customer}</element>
<element>#{order}</element>
<element>#{order.lineItems}</element>
</assertObjects>
</handler>
<transition name="approved" to="ship">
<action class="org.jboss.seam.drools.DroolsActionHandler">
<workingMemoryName>shippingRulesWorkingMemory</workingMemoryName>
<assertObjects>
<element>#{customer}</element>
<element>#{order}</element>
<element>#{order.lineItems}</element>
</assertObjects>
</action>
</transition>
<transition name="rejected" to="cancelled"/>
</decision>
The <assertObjects> element specifies EL expressions that return an object or collection of
objects to be asserted as facts into the WorkingMemory.
There is also support for using Drools for jBPM task assignments:
<task-node name="review">
<task name="review" description="Review Order">
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Chapter 13. Seam and JBoss Rules
<assignment handler="org.jboss.seam.drools.DroolsAssignmentHandler">
<workingMemoryName>orderApprovalRulesWorkingMemory</workingMemoryName>
<assertObjects>
<element>#{actor}</element>
<element>#{customer}</element>
<element>#{order}</element>
<element>#{order.lineItems}</element>
</assertObjects>
</assignment>
</task>
<transition name="rejected" to="cancelled"/>
<transition name="approved" to="approved"/>
</task-node>
Certain objects are available to the rules as Drools globals, namely the jBPM Assignable, as
assignable and a Seam Decision object, as decision. Rules which handle decisions should call
decision.setOutcome("result") to determine the result of the decision. Rules which perform
assignments should set the actor id using the Assignable.
package org.jboss.seam.examples.shop
import org.jboss.seam.drools.Decision
global Decision decision
rule "Approve Order For Loyal Customer"
when
Customer( loyaltyStatus == "GOLD" )
Order( totalAmount <= 10000 )
then
decision.setOutcome("approved");
end
package org.jboss.seam.examples.shop
import org.jbpm.taskmgmt.exe.Assignable
global Assignable assignable
rule "Assign Review For Small Order"
when
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Using rules from a jBPM process definition
Order( totalAmount <= 100 )
then
assignable.setPooledActors( new String[] {"reviewers"} );
end
219
220
Chapter 14.
Security
The Seam Security API is an optional Seam feature that provides authentication and authorization
features for securing both domain and page resources within your Seam project.
14.1. Overview
Seam Security provides two different modes of operation:
• simplified mode - this mode supports authentication services and simple role-based security
checks.
• advanced mode - this mode supports all the same features as the simplified mode, plus it offers
rule-based security checks using JBoss Rules.
14.1.1. Which mode is right for my application?
That all depends on the requirements of your application. If you have minimal security
requirements, for example if you only wish to restrict certain pages and actions to users who are
logged in, or who belong to a certain role, then the simplified mode will probably be sufficient. The
advantages of this is a more simplified configuration, significantly less libraries to include, and a
smaller memory footprint.
If on the other hand, your application requires security checks based on contextual state or
complex business rules, then you will require the features provided by the advanced mode.
14.2. Requirements
If using the advanced mode features of Seam Security, the following jar files are required to be
configured as modules in application.xml. If you are using Seam Security in simplified mode,
these are not required:
• drools-compiler.jar
• drools-core.jar
• janino.jar
• antlr-runtime.jar
• mvel14.jar
For web-based security, jboss-seam-ui.jar must also be included in the application's war file.
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14.3. Disabling Security
In some situations it may be necessary to disable Seam Security, for example during unit tests.
This can be done by calling the static method Identity.setSecurityEnabled(false) to disable
security checks. Doing this prevents any security checks being performed for the following:
• Entity Security
• Hibernate Security Interceptor
• Seam Security Interceptor
• Page restrictions
14.4. Authentication
The authentication features provided by Seam Security are built upon JAAS (Java Authentication
and Authorization Service), and as such provide a robust and highly configurable API for handling
user authentication. However, for less complex authentication requirements Seam offers a much
more simplified method of authentication that hides the complexity of JAAS.
14.4.1. Configuration
The simplified authentication method uses a built-in JAAS login module, SeamLoginModule, which
delegates authentication to one of your own Seam components. This login module is already
configured inside Seam as part of a default application policy and as such does not require any
additional configuration files. It allows you to write an authentication method using the entity
classes that are provided by your own application. Configuring this simplified form of authentication
requires the identity component to be configured in components.xml:
<components xmlns="http://jboss.com/products/seam/components"
xmlns:core="http://jboss.com/products/seam/core"
xmlns:security="http://jboss.com/products/seam/security"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation=
"http://jboss.com/products/seam/components http://jboss.com/products/seam/
components-2.1.xsd
http://jboss.com/products/seam/security http://jboss.com/products/seam/security2.1.xsd">
<security:identity authenticate-method="#{authenticator.authenticate}"/>
</components>
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Writing an authentication method
If you wish to use the advanced security features such as rule-based permission checks, all you
need to do is include the Drools (JBoss Rules) jars in your classpath, and add some additional
configuration, described later.
The EL expression #{authenticator.authenticate} is a method binding indicating that the
authenticate method of the authenticator component will be used to authenticate the user.
14.4.2. Writing an authentication method
The authenticate-method property specified for identity in components.xml specifies
which method will be used by SeamLoginModule to authenticate users. This method
takes no parameters, and is expected to return a boolean indicating whether
authentication is successful or not. The user's username and password can be obtained
from Identity.instance().getUsername() and Identity.instance().getPassword(),
respectively. Any roles that the user is a member of should be assigned using
Identity.instance().addRole(). Here's a complete example of an authentication method
inside a JavaBean component:
@Name("authenticator")
public class Authenticator {
@In EntityManager entityManager;
public boolean authenticate() {
try
{
User user = (User) entityManager.createQuery(
"from User where username = :username and password = :password")
.setParameter("username", Identity.instance().getUsername())
.setParameter("password", Identity.instance().getPassword())
.getSingleResult();
if (user.getRoles() != null)
{
for (UserRole mr : user.getRoles())
Identity.instance().addRole(mr.getName());
}
return true;
}
catch (NoResultException ex)
{
return false;
}
}
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Chapter 14. Security
}
In the above example, both User and UserRole are application-specific entity beans. The roles
parameter is populated with the roles that the user is a member of, which should be added
to the Set as literal string values, e.g. "admin", "user". In this case, if the user record is not
found and a NoResultException thrown, the authentication method returns false to indicate the
authentication failed.
14.4.2.1. Identity.addRole()
The Identity.addRole() method behaves differently depending on whether the current session
is authenticated or not. If the session is not authenticated, then addRole() should only be called
during the authentication process. When called here, the role name is placed into a temporary
list of pre-authenticated roles. Once authentication is successful, the pre-authenticated roles then
become "real" roles, and calling Identity.hasRole() for those roles will then return true. The
following sequence diagram represents the list of pre-authenticated roles as a first class object to
show more clearly how it fits in to the authentication process.
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Writing a login form
14.4.2.2. Special Considerations
When writing an authenticator method, it is important that it is kept minimal and free from any sideeffects. This is because there is no guarantee as to how many times the authenticator method will
be called by the security API, and as such it may be invoked multiple times during a single request.
Because of this, any special code that should execute upon a successful or failed authentication
should be written by implementing an event observer. See the section on Security Events further
down in this chapter for more information about which events are raised by Seam Security.
To give an example, let's say that upon a successful login that some user
statistics must be updated. We would do this by writing an event observer for the
org.jboss.seam.security.loginSuccessful event, like this:
@In UserStats userStats;
@Observer("org.jboss.seam.security.loginSuccessful")
public void updateUserStats()
{
userStats.setLastLoginDate(new Date());
userStats.incrementLoginCount();
}
14.4.3. Writing a login form
The Identity component provides both username and password properties, catering for the most
common authentication scenario. These properties can be bound directly to the username and
password fields on a login form. Once these properties are set, calling the identity.login()
method will authenticate the user using the provided credentials. Here's an example of a simple
login form:
<div>
<h:outputLabel for="name" value="Username"/>
<h:inputText id="name" value="#{identity.username}"/>
</div>
<div>
<h:outputLabel for="password" value="Password"/>
<h:inputSecret id="password" value="#{identity.password}"/>
</div>
<div>
<h:commandButton value="Login" action="#{identity.login}"/>
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Chapter 14. Security
</div>
Similarly, logging out the user is done by calling #{identity.logout}. Calling this action will
clear the security state of the currently authenticated user.
14.4.4. Simplified Configuration - Summary
So to sum up, there are the three easy steps to configure authentication:
• Configure an authentication method in components.xml.
• Write an authentication method.
• Write a login form so that the user can authenticate.
14.4.5. Handling Security Exceptions
To prevent users from receiving the default error page in response to a security error, it's
recommended that pages.xml is configured to redirect security errors to a more "pretty" page.
The two main types of exceptions thrown by the security API are:
• NotLoggedInException - This exception is thrown if the user attempts to access a restricted
action or page when they are not logged in.
• AuthorizationException - This exception is only thrown if the user is already logged in, and
they have attempted to access a restricted action or page for which they do not have the
necessary privileges.
In the case of a NotLoggedInException, it is recommended that the user is redirected to either
a login or registration page so that they can log in. For an AuthorizationException, it may be
useful to redirect the user to an error page. Here's an example of a pages.xml file that redirects
both of these security exceptions:
<pages>
...
<exception class="org.jboss.seam.security.NotLoggedInException">
<redirect view-id="/login.xhtml">
<message>You must be logged in to perform this action</message>
</redirect>
</exception>
<exception class="org.jboss.seam.security.AuthorizationException">
<end-conversation/>
<redirect view-id="/security_error.xhtml">
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Login Redirection
<message>You do not have the necessary security privileges to perform this action.</
message>
</redirect>
</exception>
</pages>
Most web applications require even more sophisticated handling of login redirection, so Seam
includes some special functionality for handling this problem.
14.4.6. Login Redirection
You can ask Seam to redirect the user to a login screen when an unauthenticated user tries to
access a particular view (or wildcarded view id) as follows:
<pages login-view-id="/login.xhtml">
<page view-id="/members/*" login-required="true"/>
...
</pages>
(This is less of a blunt instrument than the exception handler shown above, but should probably
be used in conjunction with it.)
After the user logs in, we want to automatically send them back where they came from, so they can
retry the action that required logging in. If you add the following event listeners to components.xml,
attempts to access a restricted view while not logged in will be remembered, so that upon the
user successfully logging in they will be redirected to the originally requested view, with any page
parameters that existed in the original request.
<event type="org.jboss.seam.security.notLoggedIn">
<action execute="#{redirect.captureCurrentView}"/>
</event>
<event type="org.jboss.seam.security.postAuthenticate">
<action execute="#{redirect.returnToCapturedView}"/>
</event>
Note that login redirection is implemented as a conversation-scoped mechanism, so don't end the
conversation in your authenticate() method.
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Chapter 14. Security
14.4.7. HTTP Authentication
Although not recommended for use unless absolutely necessary, Seam provides means for
authenticating using either HTTP Basic or HTTP Digest (RFC 2617) methods. To use either form
of authentication, the authentication-filter component must be enabled in components.xml:
<web:authentication-filter url-pattern="*.seam" auth-type="basic"/>
To enable the filter for basic authentication, set auth-type to basic, or for digest authentication,
set it to digest. If using digest authentication, the key and realm must also be set:
<web:authentication-filter url-pattern="*.seam" auth-type="digest" key="AA3JK34aSDlkj"
realm="My App"/>
The key can be any String value. The realm is the name of the authentication realm that is
presented to the user when they authenticate.
14.4.7.1. Writing a Digest Authenticator
If using digest authentication, your authenticator class should extend the abstract class
org.jboss.seam.security.digest.DigestAuthenticator, and use the validatePassword()
method to validate the user's plain text password against the digest request. Here is an example:
public boolean authenticate()
{
try
{
User user = (User) entityManager.createQuery(
"from User where username = :username")
.setParameter("username", identity.getUsername())
.getSingleResult();
return validatePassword(user.getPassword());
}
catch (NoResultException ex)
{
return false;
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Advanced Authentication Features
}
}
14.4.8. Advanced Authentication Features
This section explores some of the advanced features provided by the security API for addressing
more complex security requirements.
14.4.8.1. Using your container's JAAS configuration
If you would rather not use the simplified JAAS configuration provided by the Seam Security API,
you may instead delegate to the default system JAAS configuration by providing a jaas-configname property in components.xml. For example, if you are using JBoss AS and wish to use the
other policy (which uses the UsersRolesLoginModule login module provided by JBoss AS), then
the entry in components.xml would look like this:
<security:identity jaas-config-name="other"/>
Please keep in mind that doing this does not mean that your user will be authenticated in whichever
container your Seam application is deployed in. It merely instructs Seam Security to authenticate
itself using the configured JAAS security policy.
14.5. Error Messages
The security API produces a number of default faces messages for various security-related events.
The following table lists the message keys that can be used to override these messages by
specifying them in a message.properties resource file. To suppress the message, just put the
key with an empty value in the resource file.
Table 14.1. Security Message Keys
Message Key
Description
org.jboss.seam.loginSuccessful This message is produced when a user successfully logs
in via the security API.
org.jboss.seam.loginFailed
This message is produced when the login process fails,
either because the user provided an incorrect username
or password, or because authentication failed in some
other way.
org.jboss.seam.NotLoggedIn
This message is produced when a user attempts to
perform an action or access a page that requires
a security check, and the user is not currently
authenticated.
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Chapter 14. Security
Message Key
Description
org.jboss.seam.AlreadyLoggedIn This message is produced when a user that is already
authenticated attempts to log in again.
14.6. Authorization
There are a number of authorization features provided by the Seam Security API for securing
access to components, component methods, and pages. This section describes each of these. An
important thing to note is that if you wish to use any of the advanced features (such as rule-based
permissions) then your components.xml must be configured to support this - see the Configuration
section above.
14.6.1. Core concepts
Each of the authorization mechanisms provided by the Seam Security API are built upon the
concept of a user being granted roles and/or permissions. A role is a group, or type, of user that
may have been granted certain privileges for performing one or more specific actions within an
application. A permission on the other hand is a privilege (sometimes once-off) for performing a
single, specific action. It is entirely possible to build an application using nothing but permissions,
however roles offer a higher level of convenience when granting privileges to groups of users.
Roles are simple, consisting of only a name such as "admin", "user", "customer", etc. Permissions
consist of both a name and an action, and are represented within this documentation in the form
name:action, for example customer:delete, or customer:insert.
14.6.2. Securing components
Let's start by examining the simplest form of authorization, component security, starting with the
@Restrict annotation.
14.6.2.1. The @Restrict annotation
Seam components may be secured either at the method or the class level, using the @Restrict
annotation. If both a method and it's declaring class are annotated with @Restrict, the
method restriction will take precedence (and the class restriction will not apply). If a method
invocation fails a security check, then an exception will be thrown as per the contract for
Identity.checkRestriction() (see Inline Restrictions). A @Restrict on just the component
class itself is equivalent to adding @Restrict to each of its methods.
An empty @Restrict implies a permission check of componentName:methodName. Take for
example the following component method:
@Name("account")
public class AccountAction {
@Restrict public void delete() {
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Securing components
...
}
}
In this example, the implied permission required to call the delete()
method
is
account:delete.
The
equivalent
of
this
would
be
to
write
@Restrict("#{s:hasPermission('account','delete',null)}"). Now let's look at another
example:
@Restrict @Name("account")
public class AccountAction {
public void insert() {
...
}
@Restrict("#{s:hasRole('admin')}")
public void delete() {
...
}
}
This time, the component class itself is annotated with @Restrict. This means that any methods
without an overriding @Restrict annotation require an implicit permission check. In the case
of this example, the insert() method requires a permission of account:insert, while the
delete() method requires that the user is a member of the admin role.
Before we go any further, let's address the #{s:hasRole()} expression seen in the above
example. Both s:hasRole and s:hasPermission are EL functions, which delegate to the
correspondingly named methods of the Identity class. These functions can be used within any
EL expression throughout the entirety of the security API.
Being an EL expression, the value of the @Restrict annotation may reference any objects that
exist within a Seam context. This is extremely useful when performing permission checks for a
specific object instance. Look at this example:
@Name("account")
public class AccountAction {
@In Account selectedAccount;
@Restrict("#{s:hasPermission('account','modify',selectedAccount)}")
public void modify() {
selectedAccount.modify();
}
}
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Chapter 14. Security
The interesting thing to note from this example is the reference to selectedAccount seen within
the hasPermission() function call. The value of this variable will be looked up from within the
Seam context, and passed to the hasPermission() method in Identity, which in this case can
then determine if the user has the required permission for modifying the specified Account object.
14.6.2.2. Inline restrictions
Sometimes it might be desirable to perform a security check in code, without using the @Restrict
annotation. In this situation, simply use Identity.checkRestriction() to evaluate a security
expression, like this:
public void deleteCustomer() {
Identity.instance().checkRestriction("#{s:hasPermission('customer','delete',selectedCustomer)}");
}
If the expression specified doesn't evaluate to true, either
• if the user is not logged in, a NotLoggedInException exception is thrown or
• if the user is logged in, an AuthorizationException exception is thrown.
It is also possible to call the hasRole() and hasPermission() methods directly from Java code:
if (!Identity.instance().hasRole("admin"))
throw new AuthorizationException("Must be admin to perform this action");
if (!Identity.instance().hasPermission("customer", "create", null))
throw new AuthorizationException("You may not create new customers");
14.6.3. Security in the user interface
One indication of a well designed user interface is that the user is not presented with options for
which they don't have the necessary privileges to use. Seam Security allows conditional rendering
of either 1) sections of a page or 2) individual controls, based upon the privileges of the user,
using the very same EL expressions that are used for component security.
Let's take a look at some examples of interface security. First of all, let's pretend that we
have a login form that should only be rendered if the user is not already logged in. Using the
identity.isLoggedIn() property, we can write this:
<h:form class="loginForm" rendered="#{not identity.loggedIn}">
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Securing pages
If the user isn't logged in, then the login form will be rendered - very straight forward so far. Now let's
pretend there is a menu on the page that contains some actions which should only be accessible
to users in the manager role. Here's one way that these could be written:
<h:outputLink action="#{reports.listManagerReports}" rendered="#{s:hasRole('manager')}">
Manager Reports
</h:outputLink>
This is also quite straight forward. If the user is not a member of the manager role, then the
outputLink will not be rendered. The rendered attribute can generally be used on the control itself,
or on a surrounding <s:div> or <s:span> control.
Now for something more complex. Let's say you have a h:dataTable control on a page listing
records for which you may or may not wish to render action links depending on the user's
privileges. The s:hasPermission EL function allows us to pass in an object parameter which can
be used to determine whether the user has the requested permission for that object or not. Here's
how a dataTable with secured links might look:
<h:dataTable value="#{clients}" var="cl">
<h:column>
<f:facet name="header">Name</f:facet>
#{cl.name}
</h:column>
<h:column>
<f:facet name="header">City</f:facet>
#{cl.city}
</h:column>
<h:column>
<f:facet name="header">Action</f:facet>
<s:link value="Modify Client" action="#{clientAction.modify}"
rendered="#{s:hasPermission('client','modify',cl)"/>
<s:link value="Delete Client" action="#{clientAction.delete}"
rendered="#{s:hasPermission('client','delete',cl)"/>
</h:column>
</h:dataTable>
14.6.4. Securing pages
Page security requires that the application is using a pages.xml file, however is extremely simple
to configure. Simply include a <restrict/> element within the page elements that you wish to
secure. If no explicit restriction is specified by the restrict element, an implied permission of /
viewId.xhtml:render will be checked when the page is accessed via a non-faces (GET) request,
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Chapter 14. Security
and a permission of /viewId.xhtml:restore will be required when any JSF postback (form
submission) originates from the page. Otherwise, the specified restriction will be evaluated as a
standard security expression. Here's a couple of examples:
<page view-id="/settings.xhtml">
<restrict/>
</page>
This page has an implied permission of /settings.xhtml:render required for non-faces
requests and an implied permission of /settings.xhtml:restore for faces requests.
<page view-id="/reports.xhtml">
<restrict>#{s:hasRole('admin')}</restrict>
</page>
Both faces and non-faces requests to this page require that the user is a member of the admin role.
14.6.5. Securing Entities
Seam security also makes it possible to apply security restrictions to read, insert, update and
delete actions for entities.
To secure all actions for an entity class, add a @Restrict annotation on the class itself:
@Entity
@Name("customer")
@Restrict
public class Customer {
...
}
If no expression is specified in the @Restrict annotation, the default security check that is
performed is a permission check of entityName:action, where entityName is the Seam
component name of the entity (or the fully-qualified class name if no @Name is specified), and
the action is either read, insert, update or delete.
It is also possible to only restrict certain actions, by placing a @Restrict annotation on the relevent
entity lifecycle method (annotated as follows):
• @PostLoad - Called after an entity instance is loaded from the database. Use this method to
configure a read permission.
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Securing Entities
• @PrePersist - Called before a new instance of the entity is inserted. Use this method to
configure an insert permission.
• @PreUpdate - Called before an entity is updated. Use this method to configure an update
permission.
• @PreRemove - Called before an entity is deleted. Use this method to configure a delete
permission.
Here's an example of how an entity would be configured to perform a security check for any insert
operations. Please note that the method is not required to do anything, the only important thing
in regard to security is how it is annotated:
@PrePersist @Restrict
public void prePersist() {}
Using /META-INF/orm.xml
You can also specify the call back method in /META-INF/orm.xml:
<?xml version="1.0" encoding="UTF-8"?>
<entity-mappings xmlns="http://java.sun.com/xml/ns/persistence/orm"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm
http://java.sun.com/xml/ns/persistence/orm_1_0.xsd"
version="1.0">
<entity class="Customer">
<pre-persist method-name="prePersist" />
</entity>
</entity-mappings>
Of course, you still need to annotate the prePersist() method on Customer with
@Restrict
And here's an example of an entity permission rule that checks if the authenticated user is allowed
to insert a new MemberBlog record (from the seamspace example). The entity for which the
security check is being made is automatically inserted into the working memory (in this case
MemberBlog):
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Chapter 14. Security
rule InsertMemberBlog
no-loop
activation-group "permissions"
when
check: PermissionCheck(name == "memberBlog", action == "insert", granted == false)
Principal(principalName : name)
MemberBlog(member : member -> (member.getUsername().equals(principalName)))
then
check.grant();
end;
This rule will grant the permission memberBlog:insert if the currently authenticated user
(indicated by the Principal fact) has the same name as the member for which the blog entry is
being created. The "principalName : name" structure that can be seen in the Principal fact
(and other places) is a variable binding - it binds the name property of the Principal to a variable
called principalName. Variable bindings allow the value to be referred to in other places, such
as the following line which compares the member's username to the Principal name. For more
details, please refer to the JBoss Rules documentation.
Finally, we need to install a listener class that integrates Seam security with your JPA provider.
14.6.5.1. Entity security with JPA
Security checks for EJB3 entity beans are performed with an EntityListener. You can install
this listener by using the following META-INF/orm.xml file:
<?xml version="1.0" encoding="UTF-8"?>
<entity-mappings xmlns="http://java.sun.com/xml/ns/persistence/orm"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/persistence/orm http://java.sun.com/
xml/ns/persistence/orm_1_0.xsd"
version="1.0">
<persistence-unit-metadata>
<persistence-unit-defaults>
<entity-listeners>
<entity-listener class="org.jboss.seam.security.EntitySecurityListener"/>
</entity-listeners>
</persistence-unit-defaults>
</persistence-unit-metadata>
</entity-mappings>
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Writing Security Rules
14.6.5.2. Entity security with a Managed Hibernate Session
If you are using a Hibernate SessionFactory configured via Seam, and are using annotations,
or orm.xml, then you don't need to do anything special to use entity security.
14.7. Writing Security Rules
Up to this point there has been a lot of mention of permissions, but no information about how
permissions are actually defined or granted. This section completes the picture, by explaining
how permission checks are processed, and how to implement permission checks for a Seam
application.
14.7.1. Permissions Overview
So how does the security API know whether a user has the customer:modify permission
for a specific customer? Seam Security provides quite a novel method for determining user
permissions, based on JBoss Rules. A couple of the advantages of using a rule engine are 1)
a centralized location for the business logic that is behind each user permission, and 2) speed JBoss Rules uses very efficient algorithms for evaluating large numbers of complex rules involving
multiple conditions.
14.7.2. Configuring a rules file
Seam Security expects to find a RuleBase component called securityRules which it uses to
evaluate permission checks. This is configured in components.xml as follows:
<components xmlns="http://jboss.com/products/seam/components"
xmlns:core="http://jboss.com/products/seam/core"
xmlns:security="http://jboss.com/products/seam/security"
xmlns:drools="http://jboss.com/products/seam/drools"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation=
"http://jboss.com/products/seam/core http://jboss.com/products/seam/core-2.1.xsd
http://jboss.com/products/seam/components http://jboss.com/products/seam/
components-2.1.xsd
http://jboss.com/products/seam/drools http://jboss.com/products/seam/drools-2.1.xsd"
http://jboss.com/products/seam/security http://jboss.com/products/seam/security2.1.xsd">
<drools:rule-base name="securityRules">
<drools:rule-files>
<value>/META-INF/security.drl</value>
</drools:rule-files>
</drools:rule-base>
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Chapter 14. Security
</components>
Once the RuleBase component is configured, it's time to write the security rules.
14.7.3. Creating a security rules file
For this step you need to create a file called security.drl in the /META-INF directory of your
application's jar file. In actual fact this file can be called anything you want, and exist in any location
as long as it is configured appropriately in components.xml.
So what should the security rules file contain? At this stage it might be a good idea to at least
skim through the JBoss Rules documentation, however to get started here's an extremely simple
example:
package MyApplicationPermissions;
import org.jboss.seam.security.PermissionCheck;
import org.jboss.seam.security.Role;
rule CanUserDeleteCustomers
when
c: PermissionCheck(name == "customer", action == "delete")
Role(name == "admin")
then
c.grant();
end;
Let's break this down. The first thing we see is the package declaration. A package in JBoss Rules
is essentially a collection of rules. The package name can be anything you want - it doesn't relate
to anything else outside the scope of the rule base.
The next thing we can notice is a couple of import statements for the PermissionCheck and Role
classes. These imports inform the rules engine that we'll be referencing these classes within our
rules.
Finally we have the code for the rule. Each rule within a package should be given a
unique name (usually describing the purpose of the rule). In this case our rule is called
CanUserDeleteCustomers and will be used to check whether a user is allowed to delete a
customer record.
Looking at the body of the rule definition we can notice two distinct sections. Rules have what is
known as a left hand side (LHS) and a right hand side (RHS). The LHS consists of the conditional
part of the rule, i.e. a list of conditions which must be satisfied for the rule to fire. The LHS is
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Creating a security rules file
represented by the when section. The RHS is the consequence, or action section of the rule that
will only be fired if all of the conditions in the LHS are met. The RHS is represented by the then
section. The end of the rule is denoted by the end; line.
If we look at the LHS of the rule, we see two conditions listed there. Let's examine the first condition:
c: PermissionCheck(name == "customer", action == "delete")
In plain english, this condition is stating that there must exist a PermissionCheck object with a
name property equal to "customer", and an action property equal to "delete" within the working
memory.
So what is the working memory? Also known as a "stateful session" in Drools terminology,
the working memory is a session-scoped object that contains the contextual information that
is required by the rules engine to make a decision about a permission check. Each time the
hasPermission() method is called, a temporary PermissionCheck object, or Fact, is inserted
into the working memory. This PermissionCheck corresponds exactly to the permission that is
being checked, so for example if you call hasPermission("account", "create", null) then
a PermissionCheck object with a name equal to "account" and action equal to "create" will be
inserted into the working memory for the duration of the permission check.
Besides the PermissionCheck facts, there is also a org.jboss.seam.security.Role fact for
each of the roles that the authenticated user is a member of. These Role facts are synchronized
with the user's authenticated roles at the beginning of every permission check. As a consequence,
any Role object that is inserted into the working memory during the course of a permission check
will be removed before the next permission check occurs, if the authenticated user is not a member
of that role. Besides the PermissionCheck and Role facts, the working memory also contains the
java.security.Principal object that was created during the authentication process.
It
into
is
also
the
possible
to
working
memory
insert
by
additional
calling
long-lived
facts
((RuleBasedIdentity)
RuleBasedIdentity.instance()).getSecurityContext().insert(), passing the object as a
parameter. The exception to this is Role objects, which as already discussed are synchronized
at the start of each permission check.
Getting back to our simple example, we can also notice that the first line of our LHS is prefixed
with c:. This is a variable binding, and is used to refer back to the object that is matched by the
condition. Moving onto the second line of our LHS, we see this:
Role(name == "admin")
This condition simply states that there must be a Role object with a name of "admin" within the
working memory. As mentioned, user roles are inserted into the working memory at the beginning
of each permission check. So, putting both conditions together, this rule is essentially saying "I
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Chapter 14. Security
will fire if you are checking for the customer:delete permission and the user is a member of
the admin role".
So what is the consequence of the rule firing? Let's take a look at the RHS of the rule:
c.grant()
The RHS consists of Java code, and in this case is invoking the grant() method of the c object,
which as already mentioned is a variable binding for the PermissionCheck object. Besides the
name and action properties of the PermissionCheck object, there is also a granted property
which is initially set to false. Calling grant() on a PermissionCheck sets the granted property
to true, which means that the permission check was successful, allowing the user to carry out
whatever action the permission check was intended for.
14.7.3.1. Wildcard permission checks
It is possible to implement a wildcard permission check (which allows all actions for a given
permission name), by omitting the action constraint for the PermissionCheck in your rule, like
this:
rule CanDoAnythingToCustomersIfYouAreAnAdmin
when
c: PermissionCheck(name == "customer")
Role(name == "admin")
then
c.grant();
end;
This rule allows users with the admin role to perform any action for any customer permission
check.
14.8. SSL Security
Seam includes basic support for serving sensitive pages via the HTTPS protocol. This is easily
configured by specifying a scheme for the page in pages.xml. The following example shows how
the view /login.xhtml is configured to use HTTPS:
<page view-id="/login.xhtml" scheme="https"/>
This configuration is automatically extended to both s:link and s:button JSF controls, which
(when specifying the view) will also render the link using the correct protocol. Based on the
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CAPTCHA
previous example, the following link will use the HTTPS protocol because /login.xhtml is
configured to use it:
<s:link view="/login.xhtml" value="Login"/>
Browsing directly to a view when using the incorrect protocol will cause a redirect to the same
view using the correct protocol. For example, browsing to a page that has scheme="https" using
HTTP will cause a redirect to the same page using HTTPS.
It is also possible to configure a default scheme for all pages. This is useful if you wish to use
HTTPS for a only few pages. If no default scheme is specified then the normal behavior is to
continue use the current scheme. So once the user accessed a page that required HTTPS, then
HTTPS would continue to be used after the user navigated away to other non-HTTPS pages.
(While this is good for security, it is not so great for performance!). To define HTTP as the default
scheme, add this line to pages.xml:
<page view-id="*" scheme="http" />
Of course, if none of the pages in your application use HTTPS then it is not required to specify
a default scheme.
You may configure Seam to automatically invalidate the current HTTP session each time the
scheme changes. Just add this line to components.xml:
<core:servlet-session invalidate-on-scheme-change="true"/>
This option helps make your system less vulnerable to sniffing of the session id or leakage of
sensitive data from pages using HTTPS to other pages using HTTP.
14.9. CAPTCHA
Though strictly not part of the security API, Seam provides a built-in CAPTCHA (Completely
Automated Public Turing test to tell Computers and Humans Apart) algorithm to prevent
automated processes from interacting with your application.
14.9.1. Configuring the CAPTCHA Servlet
To get up and running, it is necessary to configure the Seam Resource Servlet, which will provide
the Captcha challenge images to your pages. This requires the following entry in web.xml:
<servlet>
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Chapter 14. Security
<servlet-name>Seam Resource Servlet</servlet-name>
<servlet-class>org.jboss.seam.servlet.SeamResourceServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Seam Resource Servlet</servlet-name>
<url-pattern>/seam/resource/*</url-pattern>
</servlet-mapping>
14.9.2. Adding a CAPTCHA to a form
Adding a CAPTCHA challenge to a form is extremely easy. Here's an example:
<h:graphicImage value="/seam/resource/captcha"/>
<h:inputText id="verifyCaptcha" value="#{captcha.response}" required="true">
<s:validate />
</h:inputText>
<h:message for="verifyCaptcha"/>
That's all there is to it. The graphicImage control displays the CAPTCHA challenge, and the
inputText receives the user's response. The response is automatically validated against the
CAPTCHA when the form is submitted.
14.9.3. Customising the CAPTCHA algorithm
You may customize the CAPTCHA algorithm by overriding the built-in component:
@Name("org.jboss.seam.captcha")
@Scope(SESSION)
public class HitchhikersCaptcha extends Captcha
{
@Override @Create
public void init()
{
setChallenge("What is the answer to life, the universe and everything?");
setCorrectResponse("42");
}
@Override
public BufferedImage renderChallenge()
{
BufferedImage img = super.renderChallenge();
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Security Events
img.getGraphics().drawOval(5, 3, 60, 14); //add an obscuring decoration
return img;
}
}
14.10. Security Events
The following table describes a number of events (see Chapter 6, Events, interceptors and
exception handling) raised by Seam Security.
Table 14.2. Security Events
Event Key
Description
org.jboss.seam.security.loginSuccessful
Raised when a login attempt is
successful.
org.jboss.seam.security.loginFailed
Raised when a login attempt fails.
org.jboss.seam.security.alreadyLoggedIn
Raised when a user that is already
authenticated attempts to log in
again.
org.jboss.seam.security.notLoggedIn
Raised when a security check fails
when the user is not logged in.
org.jboss.seam.security.notAuthorized
Raised when a security check fails
when the user is logged in however
doesn't have sufficient privileges.
org.jboss.seam.security.preAuthenticate
Raised
just
authentication.
org.jboss.seam.security.postAuthenticate
Raised just after user authentication.
org.jboss.seam.security.loggedOut
Raised after the user has logged out.
org.jboss.seam.security.credentialsUpdated
Raised when the user's credentials
have been changed.
org.jboss.seam.security.rememberMe
Raised
when
the
Identity's
rememberMe property is changed.
prior
to
user
14.11. Run As
Sometimes it may be necessary to perform certain operations with elevated privileges, such
as creating a new user account as an unauthenticated user. Seam Security supports such a
mechanism via the RunAsOperation class. This class allows either the Principal or Subject,
or the user's roles to be overridden for a single set of operations.
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Chapter 14. Security
The following code example demonstrates how RunAsOperation is used, by overriding its
getRoles() method to specify a set of roles to masquerade as for the duration of the operation.
The execute() method contains the code that will be executed with the elevated privileges.
new RunAsOperation() {
@Override
public String[] getRoles() {
return new String[] { "admin" };
}
public void execute() {
executePrivilegedOperation();
}
}.run();
In a similar way, the getPrincipal() or getSubject() methods can also be overriden to specify
the Principal and Subject instances to use for the duration of the operation. Finally, the run()
method is used to carry out the RunAsOperation.
14.12. Extending the Identity component
Sometimes it might be necessary to extend the Identity component if your application has special
security requirements. For example, users might be required to authenticate using a Company or
Department ID, along with their usual username and password. If permission-based security is
required then RuleBasedIdentity should be extended, otherwise Identity should be extended.
The following example shows an extended Identity component with an additional companyCode
field. The install precendence of APPLICATION ensures that this extended Identity gets installed
in preference to the built-in Identity.
@Name("org.jboss.seam.security.identity")
@Scope(SESSION)
@Install(precedence = APPLICATION)
@BypassInterceptors
@Startup
public class CustomIdentity extends Identity
{
private static final LogProvider log = Logging.getLogProvider(CustomIdentity.class);
private String companyCode;
public String getCompanyCode()
{
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Extending the Identity component
return companyCode;
}
public void setCompanyCode(String companyCode)
{
this.companyCode = companyCode;
}
@Override
public String login()
{
log.info("###### CUSTOM LOGIN CALLED ######");
return super.login();
}
}
245
246
Chapter 15.
Internationalization, localization and
themes
Seam makes it easy to build internationalized applications. First, let's walk through all the stages
needed to internationalize and localize your app. Then we'll take a look at the components Seam
bundles.
15.1. Internationalizing your app
A JEE application consists of many components and all of them must be configured properly for
your application to be localized.
Starting at the bottom, the first step is to ensure that your database server and client is using the
correct character encoding for your locale. Normally you'll want to use UTF-8. How to do this is
outside the scope of this tutorial.
15.1.1. Application server configuration
To ensure that the application server receives the request parameters in the correct encoding
from client requests you have to configure the tomcat connector. If you use Tomcat or JBoss AS,
add the URIEncoding="UTF-8" attribute to the connector configuration. For JBoss AS 4.2 change
${JBOSS_HOME}/server/(default)/deploy/jboss-web.deployer/server.xml:
<Connector port="8080" URIEncoding="UTF-8"/>
There is alternative which is probably better. You can tell JBoss AS that the encoding for the
request parameters will be taken from the request:
<Connector port="8080" useBodyEncodingForURI="true"/>
15.1.2. Translated application strings
You'll also need localized strings for all the messages in your application (for example field labels
on your views). First you need to ensure that your resource bundle is encoded using the desired
character encoding. By default ASCII is used. Although ASCII is enough for many languages, it
doesn't provide characters for all languages.
Resource bundles must be created in ASCII, or use Unicode escape codes to represent Unicode
characters. Since you don't compile a property file to byte code, there is no way to tell the JVM
which character set to use. So you must use either ASCII characters or escape characters not in
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Chapter 15. Internationalizat...
the ASCII character set. You can represent a Unicode character in any Java file using \uXXXX,
where XXXX is the hexidecimal representation of the character.
You can write your translation of labels (
<xlink>Labels</xlink>
) to your messages resource bundle in the native encoding and then convert the content of the file
into the escaped format through the tool native2ascii provided in the JDK. This tool will convert
a file written in your native encoding to one that represents non-ASCII characters as Unicode
escape sequences.
Usage of this tool is described here for Java 5 [http://java.sun.com/j2se/1.5.0/docs/tooldocs/
index.html#intl] or here for Java 6 [http://java.sun.com/javase/6/docs/technotes/tools/#intl]. For
example, to convert a file from UTF-8:
$
native2ascii
-encoding
UTF-8
messages_cs.properties
>
messages_cs_escaped.properties
15.1.3. Other encoding settings
We need to make sure that the view displays your localized data and messages using the correct
character set and also any data submitted uses the correct encoding.
To set the display character encoding, you need to use the <f:view locale="cs_CZ"/> tag (here
we tell JSF to use the Czech locale). You may want to change the encoding of the xml document
itself if you want to embed localized strings in the xml. To do this alter the encoding attribute in
xml declaration <?xml version="1.0" encoding="UTF-8"?> as required.
Also JSF/Facelets should submit any requests using the specified character encoding, but to
make sure any requests that don't specify an encoding you can force the request encoding using
a servlet filter. Configure this in components.xml:
<web:character-encoding-filter encoding="UTF-8"
override-client="true"
url-pattern="*.seam" />
15.2. Locales
Each user login session has an associated instance of java.util.Locale (available to the
application as a component named locale). Under normal circumstances, you won't need to do
any special configuration to set the locale. Seam just delegates to JSF to determine the active
locale:
• If there is a locale associated with the HTTP request (the browser locale), and that locale is in
the list of supported locales from faces-config.xml, use that locale for the rest of the session.
248
Labels
• Otherwise, if a default locale was specified in the faces-config.xml, use that locale for the
rest of the session.
• Otherwise, use the default locale of the server.
It is possible
properties
to
set
the
locale
manually
via
the
Seam
configuration
org.jboss.seam.international.localeSelector.language,
and
org.jboss.seam.international.localeSelector.variant, but we can't think of any good
reason to ever do this.
org.jboss.seam.international.localeSelector.country
It is, however, useful to allow the user to set the locale manually via the application user interface.
Seam provides built-in functionality for overriding the locale determined by the algorithm above.
All you have to do is add the following fragment to a form in your JSP or Facelets page:
<h:selectOneMenu value="#{localeSelector.language}">
<f:selectItem itemLabel="English" itemValue="en"/>
<f:selectItem itemLabel="Deutsch" itemValue="de"/>
<f:selectItem itemLabel="Francais" itemValue="fr"/>
</h:selectOneMenu>
<h:commandButton action="#{localeSelector.select}" value="#{messages['ChangeLanguage']}"/
>
Or, if you want a list of all supported locales from faces-config.xml, just use:
<h:selectOneMenu value="#{localeSelector.localeString}">
<f:selectItems value="#{localeSelector.supportedLocales}"/>
</h:selectOneMenu>
<h:commandButton action="#{localeSelector.select}" value="#{messages['ChangeLanguage']}"/
>
When this use selects an item from the drop-down, and clicks the button, the Seam and JSF
locales will be overridden for the rest of the session.
15.3. Labels
JSF supports internationalization of user interface labels and descriptive text via the use of
<f:loadBundle />. You can use this approach in Seam applications. Alternatively, you can take
advantage of the Seam messages component to display templated labels with embedded EL
expressions.
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Chapter 15. Internationalizat...
15.3.1. Defining labels
Seam
provides
a
java.util.ResourceBundle
(available
to
the
application
as
a
org.jboss.seam.core.resourceBundle). You'll need to make your internationalized labels
available via this special resource bundle. By default, the resource bundle used by Seam is
named messages and so you'll need to define your labels in files named messages.properties,
messages_en.properties, messages_en_AU.properties, etc. These files usually belong in the
WEB-INF/classes directory.
So, in messages_en.properties:
Hello=Hello
And in messages_en_AU.properties:
Hello=G'day
You can select a different name for the resource bundle by setting the Seam configuration property
named org.jboss.seam.core.resourceLoader.bundleNames. You can even specify a list of
resource bundle names to be searched (depth first) for messages.
<core:resource-loader>
<core:bundle-names>
<value>mycompany_messages</value>
<value>standard_messages</value>
</core:bundle-names>
</core:resource-loader>
If you want to define a message just for a particular page, you can specify it in a resource bundle
with the same name as the JSF view id, with the leading / and trailing file extension removed.
So we could put our message in welcome/hello_en.properties if we only needed to display
the message on /welcome/hello.jsp.
You can even specify an explicit bundle name in pages.xml:
<page view-id="/welcome/hello.jsp" bundle="HelloMessages"/>
Then we could use messages defined in
hello.jsp.
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HelloMessages.properties on
/welcome/
Displaying labels
15.3.2. Displaying labels
If you define your labels using the Seam resource bundle, you'll be able to use them without having
to type <f:loadBundle ... /> on every page. Instead, you can simply type:
<h:outputText value="#{messages['Hello']}"/>
or:
<h:outputText value="#{messages.Hello}"/>
Even better, the messages themselves may contain EL expressions:
Hello=Hello, #{user.firstName} #{user.lastName}
Hello=G'day, #{user.firstName}
You can even use the messages in your code:
@In private Map<String, String> messages;
@In("#{messages['Hello']}") private String helloMessage;
15.3.3. Faces messages
The facesMessages component is a super-convenient way to display success or failure messages
to the user. The functionality we just described also works for faces messages:
@Name("hello")
@Stateless
public class HelloBean implements Hello {
@In FacesMessages facesMessages;
public String sayIt() {
facesMessages.addFromResourceBundle("Hello");
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Chapter 15. Internationalizat...
}
}
This will display Hello, Gavin King or G'day, Gavin, depending upon the user's locale.
15.4. Timezones
There
is
also
a
session-scoped
instance
of
java.util.Timezone,
named
org.jboss.seam.international.timezone, and a Seam component for changing the timezone
named org.jboss.seam.international.timezoneSelector. By default, the timezone is the
default timezone of the server. Unfortunately, the JSF specification says that all dates and times
should be assumed to be UTC, and displayed as UTC, unless a timezone is explicitly specified
using <f:convertDateTime>. This is an extremely inconvenient default behavior.
Seam overrides this behavior, and defaults all dates and times to the Seam timezone. In addition,
Seam provides the <s:convertDateTime> tag which always performs conversions in the Seam
timezone.
15.5. Themes
Seam applications are also very easily skinnable. The theme API is very similar to the localization
API, but of course these two concerns are orthogonal, and some applications support both
localization and themes.
First, configure the set of supported themes:
<theme:theme-selector cookie-enabled="true">
<theme:available-themes>
<value>default</value>
<value>accessible</value>
<value>printable</value>
</theme:available-themes>
</theme:theme-selector>
Note that the first theme listed is the default theme.
Themes are defined in a properties file with the same name as the theme. For example,
the default theme is defined as a set of entries in default.properties. For example,
default.properties might define:
css ../screen.css
template /template.xhtml
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Persisting locale and theme preferences via
cookies
Usually the entries in a theme resource bundle will be paths to CSS styles or images and names
of facelets templates (unlike localization resource bundles which are usually text).
Now we can use these entries in our JSP or facelets pages. For example, to theme the stylesheet
in a facelets page:
<link href="#{theme.css}" rel="stylesheet" type="text/css" />
Or, when the page definition resides in a subdirectory:
<link href="#{facesContext.externalContext.requestContextPath}#{theme.css}"
rel="stylesheet" type="text/css" />
Most powerfully, facelets lets us theme the template used by a <ui:composition>:
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://java.sun.com/jsf/facelets"
xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
template="#{theme.template}">
Just like the locale selector, there is a built-in theme selector to allow the user to freely switch
themes:
<h:selectOneMenu value="#{themeSelector.theme}">
<f:selectItems value="#{themeSelector.themes}"/>
</h:selectOneMenu>
<h:commandButton action="#{themeSelector.select}" value="Select Theme"/>
15.6. Persisting locale and theme preferences via
cookies
The locale selector, theme selector and timezone selector all support persistence of locale and
theme preference to a cookie. Simply set the cookie-enabled property in components.xml:
<theme:theme-selector cookie-enabled="true">
<theme:available-themes>
<value>default</value>
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Chapter 15. Internationalizat...
<value>accessible</value>
<value>printable</value>
</theme:available-themes>
</theme:theme-selector>
<international:locale-selector cookie-enabled="true"/>
254
Chapter 16.
Seam Text
Collaboration-oriented websites require a human-friendly markup language for easy entry
of formatted text in forum posts, wiki pages, blogs, comments, etc. Seam provides the
<s:formattedText/> control for display of formatted text that conforms to the Seam Text
language. Seam Text is implemented using an ANTLR-based parser. You don't need to know
anything about ANTLR to use it, however.
16.1. Basic fomatting
Here is a simple example:
It's easy to make *emphasis*, |monospace|,
~deleted text~, super^scripts^ or _underlines_.
If we display this using <s:formattedText/>, we will get the following HTML produced:
<p>
It's easy to make <i>emphasis</i>, <tt>monospace</tt>
<del>deleted text</del>, super<sup>scripts</sup> or <u>underlines</u>.
</p>
We can use a blank line to indicate a new paragraph, and + to indicate a heading:
+This is a big heading
You /must/ have some text following a heading!
++This is a smaller heading
This is the first paragraph. We can split it across multiple
lines, but we must end it with a blank line.
This is the second paragraph.
(Note that a simple newline is ignored, you need an additional blank line to wrap text into a new
paragraph.) This is the HTML that results:
<h1>This is a big heading</h1>
<p>
You <i>must</i> have some text following a heading!
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Chapter 16. Seam Text
</p>
<h2>This is a smaller heading</h2>
<p>
This is the first paragraph. We can split it across multiple
lines, but we must end it with a blank line.
</p>
<p>
This is the second paragraph.
</p>
Ordered lists are created using the # character. Unordered lists use the = character:
An ordered list:
#first item
#second item
#and even the /third/ item
An unordered list:
=an item
=another item
<p>
An ordered list:
</p>
<ol>
<li>first item</li>
<li>second item</li>
<li>and even the <i>third</i> item</li>
</ol>
<p>
An unordered list:
</p>
<ul>
<li>an item</li>
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Entering code and text with special characters
<li>another item</li>
</ul>
Quoted sections should be surrounded in double quotes:
The other guy said:
"Nyeah nyeah-nee
/nyeah/ nyeah!"
But what do you think he means by "nyeah-nee"?
<p>
The other guy said:
</p>
<q>Nyeah nyeah-nee
<i>nyeah</i> nyeah!</q>
<p>
But what do you think he means by <q>nyeah-nee</q>?
</p>
16.2. Entering code and text with special characters
Special characters such as *, | and #, along with HTML characters such as <, > and & may be
escaped using \:
You can write down equations like 2\*3\=6 and HTML tags
like \<body\> using the escape character: \\.
<p>
You can write down equations like 2*3=6 and HTML tags
like &lt;body&gt; using the escape character: \.
</p>
And we can quote code blocks using backticks:
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Chapter 16. Seam Text
My code doesn't work:
`for (int i=0; i<100; i--)
{
doSomething();
}`
Any ideas?
<p>
My code doesn't work:
</p>
<pre>for (int i=0; i&lt;100; i--)
{
doSomething();
}</pre>
<p>
Any ideas?
</p>
Note that inline monospace formatting always escapes (most monospace formatted text is in fact
code or tags with many special characters). So you can, for example, write:
This is a |<tag attribute="value"/>| example.
without escaping any of the characters inside the monospace bars. The downside is that you can't
format inline monospace text in any other way (italics, underscore, and so on).
16.3. Links
A link may be created using the following syntax:
Go to the Seam website at [=>http://jboss.com/products/seam].
Or, if you want to specify the text of the link:
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Entering HTML
Go to [the Seam website=>http://jboss.com/products/seam].
For advanced users, it is even possible to customize the Seam Text parser to understand wikiword
links written using this syntax.
16.4. Entering HTML
Text may even include a certain limited subset of HTML (don't worry, the subset is chosen to be
safe from cross-site scripting attacks). This is useful for creating links:
You might want to link to <a href="http://jboss.com/products/seam">something
cool</a>, or even include an image: <img src="/logo.jpg"/>
And for creating tables:
<table>
<tr><td>First name:</td><td>Gavin</td></tr>
<tr><td>Last name:</td><td>King</td></tr>
</table>
But you can do much more if you want!
259
260
Chapter 17.
iText PDF generation
Seam now includes a component set for generating documents using iText. The primary focus of
Seam's iText document support is for the generation of PDF doucuments, but Seam also offers
basic support for RTF document generation.
17.1. Using PDF Support
iText support is provided by jboss-seam-pdf.jar. This JAR contains the iText JSF controls,
which are used to construct views that can render to PDF, and the DocumentStore component,
which serves the rendered documents to the user. To include PDF support in your application,
included jboss-seam-pdf.jar in your WEB-INF/lib directory along with the iText JAR file. There
is no further configuration needed to use Seam's ciText supportfon.
The Seam iText module requires the use of Facelets as the view technology. Future versions of the
library may also support the use of JSP. Additionally, it requires the use of the seam-ui package.
The examples/itext project contains an example of the PDF support in action. It demonstrates
proper deployment packaging, and it contains a number examples that demonstrate the key PDF
generation features current supported.
17.1.1. Creating a document
<p:document>
Description
Documents are generated by facelet XHTML files using tags in
the http://jboss.com/products/seam/pdf namespace. Documents
should always have the document tag at the root of the document.
The document tag prepares Seam to generate a document into the
DocumentStore and renders an HTML redirect to that stored content.
Attributes
• type — The type of the document to be produced. Valid values
are PDF, RTF and HTML modes. Seam defaults to PDF generation,
and many of the features only work correctly when generating PDF
documents.
• pageSize — The size of the page to be generate. The
most commonly used values would be LETTER and A4.
A full list of supported pages sizes can be found in
com.lowagie.text.PageSize class. Alternatively, pageSize can
provide the width and height of the page directly. The value "612 792",
for example, is equivalent to the LETTER page size.
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Chapter 17. iText PDF generation
• orientation — The orientation of the page. Valid values are
portrait and landscape. In landscape mode, the height and width
page size values are reversed.
• margins — The left, right, top and bottom margin values.
• marginMirroring — Indicates that margin settings should be
reversed an alternating pages.
• disposition — When generating PDFs in a web browser, this
determines the HTTP Content-Disposition of the document. Valid
values are inline, which indicates the document should be displayed
in the browser window if possible, and attachment, which indicates
that the document should be treated as a download. The default value
is inline.
Metadata Attributes
• title
• subject
• keywords
• author
• creator
Usage
<p:document xmlns:p="http://jboss.com/products/seam/pdf">
The document goes here.
</p:document>
17.1.2. Basic Text Elements
Useful documents will need to contain more than just text; however, the standard UI components
are geared towards HTML generation and are not useful for generating PDF content. Instead,
Seam provides a special UI components for generating suitable PDF content. Tags like <p:image>
and <p:paragraph> are the basic foundations of simple documents. Tags like <p:font> provide
style information to all the content surrounging them.
<p:paragraph>
262
Description
Basic Text Elements
Most uses of text should be sectioned into paragraphs so that text
fragments can be flowed, formatted and styled in logical groups.
Attributes
• firstLineIndent
• extraParagraphSpace
• leading
• multipliedLeading
• spacingBefore — The blank space to be inserted before the
element.
• spacingAfter — The blank space to be inserted after the element.
• indentationLeft
• indentationRight
• keepTogether
Usage
<p:paragraph alignment="justify">
This is a simple document. It isn't very fancy.
</p:paragraph>
<p:text>
Description
The text tag allows text fragments to be produced from application
data using normal JSF converter mechanisms. It is very similar to the
outputText tag used when rendering HTML documents.
Attributes
• value — The value to be displayed. This will typically be a value
binding expression.
Usage
<p:paragraph>
The item costs <p:text value="#{product.price}">
<f:convertNumber type="currency" currencySymbol="$"/>
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Chapter 17. iText PDF generation
</p:text>
</p:paragraph>
<p:html>
Description
The html tag renders HTML content into the PDF.
Attributes
• value — The text to be displayed.
Usage
<p:html value="This is HTML with <b>some markup</b>." />
<p:html>
<h1>This is more complex HTML</h1>
<ul>
<li>one</li>
<li>two</li>
<li>three</li>
</ul>
</p:html>
<p:html>
<s:formattedText value="*This* is |Seam Text| as HTML.
very^cool^." />
</p:html>
<p:font>
It's
Description
The font tag defines the default font to be used for all text inside of it.
Attributes
• name — The font name, for example: COURIER, HELVETICA, TIMESROMAN, SYMBOL or ZAPFDINGBATS.
• size — The point size of the font.
• style — The font styles. Any combination of : NORMAL, BOLD, ITALIC,
OBLIQUE, UNDERLINE, LINE-THROUGH
• encoding — The character set encoding.
Usage
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Basic Text Elements
<p:font name="courier" style="bold" size="24">
<p:paragraph>My Title</p:paragraph>
</p:font>
<p:newPage>
Description
p:newPage inserts a page break.
Usage
<p:newPage />
<p:image>
Description
p:image inserts an image into the document. Images can be be loaded
from the classpath or from the web application context using the value
attribute.
Resources can also be dynamically generated by application code.
The imageData attribute can specify a value binding expression whose
value is a java.awt.Image object.
Attributes
• value — A resource name or a method expression binding to an
application-generated image.
• rotation — The rotation of the image in degrees.
• height — The height of the image.
• width — The width of the image.
• alignment— The alignment of the image. (see Section 17.1.7.2,
“Alignment Values” for possible values)
• alt — Alternative text representation for the image.
• indentationLeft
• indentationRight
• spacingBefore — The blank space to be inserted before the
element.
• spacingAfter — The blank space to be inserted after the element.
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Chapter 17. iText PDF generation
• widthPercentage
• initialRotation
• dpi
• scalePercent — The scaling factor (as a percentage) to use for
the image. This can be expressed as a single percentage value or
as two percentage values representing separate x and y scaling
percentages.
• wrap
• underlying
Usage
<p:image value="/jboss.jpg" />
<p:image value="#{images.chart}" />
<p:anchor>
Description
p:anchor defines clickable links from a document. It supports the
following attributes:
Attributes
• name — The name of an in-document anchor destination.
• reference — The destination the link refers to. Links to other points
in the document should begin with a "#". For example, "#link1" to refer
to an anchor postion with a name of link1. Links may also be a full
URL to point to a resource outside of the document.
Usage
<p:listItem><p:anchor reference="#reason1">Reason 1</p:anchor></
p:listItem>
...
<p:paragraph>
<p:anchor name="reason1">It's the quickest way to get "rich"</
p:anchor>
...
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Headers and Footers
</p:paragraph>
17.1.3. Headers and Footers
<p:header>
Description
<p:footer>
The p:header and p:footer components provide the ability to place
header and footer text on each page of a generated document, with
the exception of the first page. Header and footer declarations should
appear near the top of a document.
Attributes
• alignment — The alignment of the header/footer box section. (see
Section 17.1.7.2, “Alignment Values” for alignment values)
• backgroundColor — The background color of the header/footer box.
(see Section 17.1.7.1, “Color Values” for color values)
• borderColor
—
The
border
color
of
the
header/
footer box. Individual border sides can be set using
borderColorLeft, borderColorRight, borderColorTop and
borderColorBottom.(see Section 17.1.7.1, “Color Values” for color
values)
• borderWidth — The width of the border. Inidvidual border sides
can be specified using borderWidthLeft, borderWidthRight,
borderWidthTop and borderWidthBottom.
Usage
<p:facet name="header">
<p:font size="12">
<p:footer borderWidthTop="1" borderColorTop="blue"
borderWidthBottom="0" alignment="center">
Why Seam? [<p:pageNumber />]
</p:footer>
</p:font>
</f:facet>
<p:pageNumber>
Description
The current page number can be placed inside of a header or footer
using the p:pageNumber tag. The page number tag can only be used in
the context of a header or footer and can only be used once.
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Chapter 17. iText PDF generation
Usage
<p:footer borderWidthTop="1" borderColorTop="blue"
borderWidthBottom="0" alignment="center">
Why Seam? [<p:pageNumber />]
</p:footer>
17.1.4. Chapters and Sections
<p:chapter>
Description
<p:section>
If the generated document follows a book/article structure, the
p:chapter and p:section tags can be used to provide the necessary
structure. Sections can only be used inside of chapters, but they may
be nested arbitrarily deep. Most PDF viewers provide easy navigation
between chapters and sections in a document.
Attributes
• alignment — The alignment of the header/footer box section. (see
Section 17.1.7.2, “Alignment Values” for alignment values)
• number — The chapter number. Every chapter should be assigned
a chapter number.
• numberDepth — The depth of numbering for section. All sections are
numbered relative to their surrounding chapter/sections. The fourth
section of of the first section of chapter three would be section 3.1.4,
if displayed at the default number depth of three. To omit the chapter
number, a number depth of 2 should be used. In that case, the section
number would be displayed as 1.4.
Usage
<p:document xmlns:p="http://jboss.com/products/seam/pdf"
title="Hello">
<p:chapter number="1">
<p:title><p:paragraph>Hello</p:paragraph></p:title>
<p:paragraph>Hello #{user.name}!</p:paragraph>
</p:chapter>
<p:chapter number="2">
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Lists
<p:title><p:paragraph>Goodbye</p:paragraph></p:title>
<p:paragraph>Goodbye #{user.name}.</p:paragraph>
</p:chapter>
</p:document>
<p:header>
Description
Any chapter or section can contain a p:title. The title will be displayed
next to the chapter/section number. The body of the title may contain
raw text or may be a p:paragraph.
17.1.5. Lists
List structures can be displayed using the p:list and p:listItem tags. Lists may contain
arbitrarily-nested sublists. List items may not be used outside of a list. he following document uses
the ui:repeat tag to to display a list of values retrieved from a Seam component.
<p:document xmlns:p="http://jboss.com/products/seam/pdf"
xmlns:ui="http://java.sun.com/jsf/facelets"
title="Hello">
<p:list style="numbered">
<ui:repeat value="#{documents}" var="doc">
<p:listItem>#{doc.name}</p:listItem>
</ui:repeat>
</p:list>
</p:document>
<p:list>
Attributes
• style — The ordering/bulleting style of list. One of: NUMBERED,
LETTERED, GREEK, ROMAN, ZAPFDINGBATS, ZAPFDINGBATS_NUMBER. If
no style is given, the list items are bulleted.
• listSymbol — For bulleted lists, specifies the bullet symbol.
• indent — The indentation level of the list.
• lowerCase — For list styles using letters, indicates whether the letters
should be lower case.
• charNumber — For ZAPFDINGBATS, indicates the character code
of the bullet character.
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Chapter 17. iText PDF generation
• numberType — For ZAPFDINGBATS_NUMBER, indicates the
numbering style.
Usage
<p:list style="numbered">
<ui:repeat value="#{documents}" var="doc">
<p:listItem>#{doc.name}</p:listItem>
</ui:repeat>
</p:list>
<p:listItem>
Description
p:listItem supports the following attributes:
Attributes
• alignment — The alignment of the header/footer box section. (see
Section 17.1.7.2, “Alignment Values” for alignment values)
• alignment — The alignment of the list item. (See Section 17.1.7.2,
“Alignment Values” for possible values)
• indentationLeft — The left indentation amount.
• indentationRight — The right indentation amount.
• listSymbol — Overrides the default list symbol for this list item.
Usage
...
17.1.6. Tables
Table structures can be created using the p:table and p:cell tags. Unlike many table structures,
there is no explicit row declaration. If a table has 3 columns, then every 3 cells will automatically
form a row. Header and footer rows can be declared, and the headers and footers will be repeated
in the event a table structure spans multiple pages.
<p:table>
Description
p:table supports the following attributes.
Attributes
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Tables
• columns — The number of columns (cells) that make up a table row.
• widths — The relative widths of each column. There should be one
value for each column. For example: widths="2 1 1" would indicate
that there are 3 columns and the first column should be twice the size
of the second and third column.
• headerRows — The initial number of rows which are considered to
be headers or footer rows and should be repeated if the table spans
multiple pages.
• footerRows — The number of rows that are considered to be
footer rows. This value is subtracted from the headerRows value. If
document has 2 rows which make up the header and one row that
makes up the footer, headerRows should be set to 3 and footerRows
should be set to 1
• widthPercentage — The percentage of the page width that the table
spans.
• horizontalAlignment — The horizontal alignment of the table. (See
Section 17.1.7.2, “Alignment Values” for possible values)
• skipFirstHeader
• runDirection
• lockedWidth
• splitRows
• spacingBefore — The blank space to be inserted before the
element.
• spacingAfter — The blank space to be inserted after the element.
• extendLastRow
• headersInEvent
• splitLate
• keepTogether
Usage
<p:table columns="3" headerRows="1">
<p:cell>name</p:cell>
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<p:cell>owner</p:cell>
<p:cell>size</p:cell>
<ui:repeat value="#{documents}" var="doc">
<p:cell>#{doc.name}</p:cell>
<p:cell>#{doc.user.name}</p:cell>
<p:cell>#{doc.size}</p:cell>
</ui:repeat>
</p:table>
<p:cell>
Description
p:cell supports the following attributes.
Attributes
• colspan — Cells can span more than one column by declaring a
colspan greater than 1. Tables do not have the ability to span across
multiple rows.
• horizontalAlignment — The horizontal alignment of the cell. (see
Section 17.1.7.2, “Alignment Values” for possible values)
• verticalAlignment — The vertical alignment of the cell. (see
Section 17.1.7.2, “Alignment Values” for possible values)
• padding — Padding on a given side can also be specified using
paddingLeft, paddingRight, paddingTop and paddingBottom.
• useBorderPadding
• leading
• multipliedLeading
• indent
• verticalAlignment
• extraParagraphSpace
• fixedHeight
• noWrap
• minimumHeight
• followingIndent
• rightIndent
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Document Constants
• spaceCharRatio
• runDirection
• arabicOptions
• useAscender
• grayFill
• rotation
Usage
<p:cell>...</p:cell>
17.1.7. Document Constants
This section documents some of the constants shared by attributes on multiple tags.
17.1.7.1. Color Values
Seam documents do not yet support a full color specification. Currently, only named colors are
supported. They are: white, gray, lightgray, darkgray, black, red, pink, yellow, green,
magenta, cyan and blue.
17.1.7.2. Alignment Values
Where alignment values are used, the Seam PDF supports the following horizontal alignment
values: left, right, center, justify and justifyall. The vertical alignment values are top,
middle, bottom, and baseline.
17.1.8. Configuring iText
Document generation works out of the box with no additional configuration needed. However,
there are a few points of configuration that are needed for more serious applications.
The default implementation serves PDF documents from a generic URL, /seam-doc.seam.
Many browsers (and users) would prefer to see URLs that contain the actual PDF name like
/myDocument.pdf. This capability requires some configuration. To serve PDF files, all *.pdf
resources should be mapped to the DocumentStoreServlet:
<servlet>
<servlet-name>Document Store Servlet</servlet-name>
<servlet-class>org.jboss.seam.pdf.DocumentStoreServlet</servlet-class>
</servlet>
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<servlet-mapping>
<servlet-name>Document Store Servlet</servlet-name>
<url-pattern>*.pdf</url-pattern>
</servlet-mapping>
The use-extensions option on the document store component completes the functionality by
instructing the document store to generate URLs with the correct filename extension for the
document type being generated.
<components xmlns="http://jboss.com/products/seam/components"
xmlns:pdf="http://jboss.com/products/seam/pdf">
<pdf:document-store use-extensions="true" />
</components>
Generated documents are stored in conversation scope and will expire when the conversation
ends. At that point, references to the document will be invalid. To You can specify a default view to
be shown when a document does not exist using the error-page property of the documentStore.
<pdf:document-store use-extensions="true" error-page="/pdfMissing.seam" />
17.2. Charting
Charting support is also provided with jboss-seam-pdf.jar. Charts can be used in PDF
documents or can be used as images in an HTML page. Charting requires the JFreeChart library
(jfreechart.jar and jcommon.jar) to be added to the WEB-INF/lib directory. Three types of
charts are currently supported: pie charts, bar charts and line charts.
<p:barchart>
Description
Displays a bar chart.
Attributes
• borderVisible — Controls whether or not a border is displayed
around the entire chart.
• borderPaint — The color of the border, if visible;
• borderBackgroundPaint — The default background color of the
chart.
• borderStroke —
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• domainAxisLabel — The text label for the domain axis.
• domainAxisPaint — The color of the domain axis label.
• domainGridlinesVisible— Controls whether or not gridlines for the
domain axis are shown on the chart.
• domainGridlinePaint— The color of the domain gridlines, if visible.
• domainGridlineStroke — The stroke style of the domain gridleines,
if visible.
• height — The height of the chart.
• width — The width of the chart.
• is3D — A boolean value indicating that the chart should be rendered
in 3D instead of 2D.
• legend — A boolean value indicating whether or not the chart should
include a legend.
• legendItemPaint— The default color of the text labels in the legend.
• legendItemBackgoundPaint— The background color for the legend,
if different from the chart background color.
• orientation — The orientation of the plot, either vertical (the
default) or horizontal.
• plotBackgroundPaint— The color of the plot background.
• plotBackgroundAlpha— The alpha (transparency) level of the
plot background. It should be a number between 0 (completely
transparent) and 1 (completely opaque).
• plotForegroundAlpha— The alpha (transparency) level of the plot.
It should be a number between 0 (completely transparent) and 1
(completely opaque).
• plotOutlinePaint— The color of the range gridlines, if visible.
• plotOutlineStroke — The stroke style of the range gridleines, if
visible.
• rangeAxisLabel — The text label for the range axis.
• rangeAxisPaint — The color of the range axis label.
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• rangeGridlinesVisible— Controls whether or not gridlines for the
range axis are shown on the chart.
• rangeGridlinePaint— The color of the range gridlines, if visible.
• rangeGridlineStroke — The stroke style of the range gridleines, if
visible.
• title — The chart title text.
• titlePaint— The color of the chart title text.
• titleBackgroundPaint— The background color around the chart
title.
• width — The width of the chart.
Usage
<p:barchart title="Bar Chart" legend="true"
width="500" height="500">
<p:series key="Last Year">
<p:data columnKey="Joe" value="100" />
<p:data columnKey="Bob" value="120" />
</p:series>
<p:series key="This Year">
<p:data columnKey="Joe" value="125" />
<p:data columnKey="Bob" value="115" />
</p:series>
</p:barchart>
<p:linechart>
Description
Displays a line chart.
Attributes
• borderVisible — Controls whether or not a border is displayed
around the entire chart.
• borderPaint — The color of the border, if visible;
• borderBackgroundPaint — The default background color of the
chart.
• borderStroke —
• domainAxisLabel — The text label for the domain axis.
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Charting
• domainAxisPaint — The color of the domain axis label.
• domainGridlinesVisible— Controls whether or not gridlines for the
domain axis are shown on the chart.
• domainGridlinePaint— The color of the domain gridlines, if visible.
• domainGridlineStroke — The stroke style of the domain gridleines,
if visible.
• height — The height of the chart.
• width — The width of the chart.
• is3D — A boolean value indicating that the chart should be rendered
in 3D instead of 2D.
• legend — A boolean value indicating whether or not the chart should
include a legend.
• legendItemPaint— The default color of the text labels in the legend.
• legendItemBackgoundPaint— The background color for the legend,
if different from the chart background color.
• orientation — The orientation of the plot, either vertical (the
default) or horizontal.
• plotBackgroundPaint— The color of the plot background.
• plotBackgroundAlpha— The alpha (transparency) level of the
plot background. It should be a number between 0 (completely
transparent) and 1 (completely opaque).
• plotForegroundAlpha— The alpha (transparency) level of the plot.
It should be a number between 0 (completely transparent) and 1
(completely opaque).
• plotOutlinePaint— The color of the range gridlines, if visible.
• plotOutlineStroke — The stroke style of the range gridleines, if
visible.
• rangeAxisLabel — The text label for the range axis.
• rangeAxisPaint — The color of the range axis label.
• rangeGridlinesVisible— Controls whether or not gridlines for the
range axis are shown on the chart.
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• rangeGridlinePaint— The color of the range gridlines, if visible.
• rangeGridlineStroke — The stroke style of the range gridleines, if
visible.
• title — The chart title text.
• titlePaint— The color of the chart title text.
• titleBackgroundPaint— The background color around the chart
title.
• width — The width of the chart.
Usage
<p:linechart title="Line Chart"
width="500" height="500">
<p:series key="Prices">
<p:data columnKey="2003" value="7.36" />
<p:data columnKey="2004" value="11.50" />
<p:data columnKey="2005" value="34.625" />
<p:data columnKey="2006" value="76.30" />
<p:data columnKey="2007" value="85.05" />
</p:series>
</p:linechart>
<p:piechart>
Description
Displays a pie chart.
Attributes
• title— The chart title text.
• label— The default label text for pie sections.
• legend— A boolean value indicating whether or not the chart should
include a legend. Default value is true
• is3D—A boolean value indicating that the chart should be rendered
in 3D instead of 2D.
• labelLinkMargin— The link margin for labels.
• labelLinkPaint— The paint used for the label linking lines.
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Charting
• labelLinkStroke— he stroke used for the label linking lines.
• labelLinksVisible— A flag that controls whether or not the label
links are drawn.
• labelOutlinePaint— The paint used to draw the outline of the
section labels.
• labelOutlineStroke— The stroke used to draw the outline of the
section labels.
• labelShadowPaint— The paint used to draw the shadow for the
section labels.
• labelPaint— The color used to draw the section labels
• labelGap— The gap between the labels and the plot as a percentage
of the plot width.
• labelBackgroundPaint— The color used to draw the background of
the section labels. If this is null, the background is not filled.
• startAngle— The starting angle of the first section.
• circular— A boolean value indicating that the chart should be drawn
as a circle. If false, the chart is drawn as an ellipse. The default is true.
• direction— The direction the pie section are drawn. One of:
clockwise or anticlockwise. The default is clockwise.
• sectionOutlinePaint— The outline paint for all sections.
• sectionOutlineStroke— The outline stroke for all sections
• sectionOutlinesVisible— Indicates whether an outline is drawn
for each section in the plot.
• baseSectionOutlinePaint— The base section outline paint.
• baseSectionPaint— The base section paint.
• baseSectionOutlineStroke— The base section outline stroke.
Usage
<p:piechart title="Pie Chart" circular="false" direction="anticlockwise"
startAngle="30" labelGap="0.1" labelLinkPaint="red">
<p:series key="Prices">
<p:data key="2003" columnKey="2003" value="7.36" />
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<p:data key="2004" columnKey="2004" value="11.50" />
<p:data key="2005" columnKey="2005" value="34.625" />
<p:data key="2006" columnKey="2006" value="76.30" />
<p:data key="2007" columnKey="2007" value="85.05" />
</p:series>
</p:piechart>
<p:series>
Description
Category data can be broken down into series. The series tag is used
to categorize a set of data with a series and apply styling to the entire
series.
Attributes
• key — The series name.
• seriesPaint — The color of each item in the series
• seriesOutlinePaint — The outline color for each item in the series.
• seriesOutlineStroke — The stroke used to draw each item in the
series.
• seriesVisible — A boolean indicating if the series should be
displayed.
• seriesVisibleInLegend — A boolean indiciating if the series should
be listed in the legend.
Usage
<p:series key="data1">
<ui:repeat value="#{data.pieData1}" var="item">
<p:data columnKey="#{item.name}" value="#{item.value}" />
</ui:repeat>
</p:series>
<p:data>
Description
The data tag describes each data point to be displayed in the graph.
Attributes
• key — The name of the data item.
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Charting
• series — The series name, when not embedded inside a
<p:series>.
• value — The numeric data value.
• explodedPercent — For pie charts, indicates how exploded a from
the pie a piece is.
• sectionOutlinePaint — For bar charts, the color of the section
outline.
• sectionOutlineStroke — For bar charts, the stroke type for the
section outline.
• sectionPaint — For bar charts, the color of the section.
Usage
<p:data key="foo" value="20" sectionPaint="#111111"
explodedPercent=".2" />
<p:data key="bar" value="30" sectionPaint="#333333" />
<p:data key="baz" value="40" sectionPaint="#555555"
sectionOutlineStroke="my-dot-style" />
<p:color>
Description
The color component declares a color or gradient than can be
referenced when drawing filled shapes.
Attributes
• color — The color value. For gradient colors, this the starting color.
Section 17.1.7.1, “Color Values”
• color2 — For gradient colors, this is the color that ends the gradient.
• point — The co-ordinates where the gradient color begins.
• point2 — The co-ordinates where the gradient color ends.
Usage
<p:color id="foo" color="#0ff00f"/>
<p:color id="bar" color="#ff00ff" color2="#00ff00"
point="50 50" point2="300 300"/>
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<p:stroke>
Description
Describes a stroke used to draw lines in a chart.
Attributes
• width — The width of the stroke.
• cap — The line cap type. Valid values are butt, round and square
• join — The line join type. Valid values are miter, round and bevel
• miterLimit — For miter joins, this value is the limit of the size of
the join.
• dash — The dash value sets the dash pattern to be used to draw
the line. The space separated integers indicate the length of each
alternating drawn and undrawn segments.
• dashPhase — The dash phase indicates the offset into the dash
pattern that the the line should be drawn with.
Usage
<p:stroke id="dot2" width="2" cap="round" join="bevel" dash="2 3" />
17.3. Bar codes
Seam can use iText to generate barcodes in a wide variety of formats. These barcodes can be
embedded in a PDF document or displayed as an image on a web page. Note that when used
with HTML images, barcodes can not currently display barcode text in the barcode.
<p:barCode>
Description
Displays a barcode image.
Attributes
• type — A barcode type supported by iText. Valid values include:
EAN13, EAN8, UPCA, UPCE, SUPP2, SUPP5, POSTNET, PLANET, CODE128,
CODE128_UCC, CODE128_RAW and CODABAR.
• code— The value to be encoded by the barcode.
• xpos— For PDFs, the absolute y position of the barcode on the page.
• ypos— For PDFs, the absolute y position of the barcode on the page.
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Rendering Swing/AWT components
• rotDegrees — For PDFs, the rotation factor of the barcode in
degrees.
• barHeight — The height of the bars in the barCode
• minBarWidth — The minimum bar width.
• barMultiplier — The bar multiplier for wide bars or the distance
between bars for POSTNET and PLANET code.
• barColor — The color to draw the bars.
• textColor — The color of any text on the barcode.
• textSize — The size of the barcode text, if any.
• altText — The alt text for HTML image links.
Usage
<p:barCode type="code128"
barHeight="80"
textSize="20"
code="(10)45566(17)040301"
codeType="code128_ucc"
altText="My BarCode" />
17.4. Rendering Swing/AWT components
Seam now provides experimental support for rendering Swing components to into a PDF image.
Some Swing look and feels supports, notably ones that use native widgets, will not render
correctly.
<p:swing>
Description
Renders a Swing component into a PDF document.
Attributes
• width — The width of the component to be rendered.
• height — ..The height of the component to be rendered.
• component — An expression whose value is a Swing or AWT
component.
Usage
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<p:swing width="310" height="120" component="#{aButton}" />
17.5. Further documentation
For further information on iText, see:
• iText Home Page [http://www.lowagie.com/iText/]
• iText in Action [http://www.manning.com/lowagie/]
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Email
Seam now includes an optional components for templating and sending emails.
Email support is provided by jboss-seam-mail.jar. This JAR contains the mail JSF controls,
which are used to construct emails, and the mailSession manager component.
The examples/mail project contains an example of the email support in action. It demonstrates
proper packaging, and it contains a number of example that demonstrate the key features currently
supported.
You can also test your mail's using Seam's integration testing environment. See Section 31.3.4,
“Integration Testing Seam Mail”.
18.1. Creating a message
You don't need to learn a whole new templating language to use Seam Mail — an email is just
facelet!
<m:message xmlns="http://www.w3.org/1999/xhtml"
xmlns:m="http://jboss.com/products/seam/mail"
xmlns:h="http://java.sun.com/jsf/html">
<m:from name="Peter" address="[email protected]" />
<m:to name="#{person.firstname} #{person.lastname}">#{person.address}</m:to>
<m:subject>Try out Seam!</m:subject>
<m:body>
<p><h:outputText value="Dear #{person.firstname}" />,</p>
<p>You can try out Seam by visiting
<a href="http://labs.jboss.com/jbossseam">http://labs.jboss.com/jbossseam</a>.</p>
<p>Regards,</p>
<p>Pete</p>
</m:body>
</m:message>
The <m:message> tag wraps the whole message, and tells Seam to start rendering an email. Inside
the <m:message> tag we use an <m:from> tag to set who the message is from, a <m:to> tag to
specify a sender (notice how we use EL as we would in a normal facelet), and a <m:subject> tag.
The <m:body> tag wraps the body of the email. You can use regular HTML tags inside the body
as well as JSF components.
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So, now you have your email template, how do you go about sending it? Well, at the end of
rendering the m:message the mailSession is called to send the email, so all you have to do is
ask Seam to render the view:
@In(create=true)
private Renderer renderer;
public void send() {
try {
renderer.render("/simple.xhtml");
facesMessages.add("Email sent successfully");
}
catch (Exception e) {
facesMessages.add("Email sending failed: " + e.getMessage());
}
}
If, for example, you entered an invalid email address, then an exception would be thrown, which
is caught and then displayed to the user.
18.1.1. Attachments
Seam makes it easy to attach files to an email. It supports most of the standard java types used
when working with files.
If you wanted to email the jboss-seam-mail.jar:
<m:attachment value="/WEB-INF/lib/jboss-seam-mail.jar"/>
Seam will load the file from the classpath, and attach it to the email. By default it would be attached
as jboss-seam-mail.jar; if you wanted it to have another name you would just add the fileName
attribute:
<m:attachment value="/WEB-INF/lib/jboss-seam-mail.jar" fileName="this-is-so-cool.jar"/>
You could also attach a java.io.File, a java.net.URL:
<m:attachment value="#{numbers}"/>
Or a byte[] or a java.io.InputStream:
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Attachments
<m:attachment value="#{person.photo}" contentType="image/png"/>
You'll notice that for a byte[] and a java.io.InputStream you need to specify the MIME type
of the attachment (as that information is not carried as part of the file).
And it gets even better, you can attach a Seam generated PDF, or any standard JSF view, just
by wrapping a <m:attachment> around the normal tags you would use:
<m:attachment fileName="tiny.pdf">
<p:document>
A very tiny PDF
</p:document>
</m:attachment>
If you had a set of files you wanted to attach (for example a set of pictures loaded from a database)
you can just use a <ui:repeat>:
<ui:repeat value="#{people}" var="person">
<m:attachment
value="#{person.photo}"
fileName="#{person.firstname}_#{person.lastname}.jpg"/>
</ui:repeat>
contentType="image/jpeg"
And if you want to display an attached image inline:
<m:attachment
value="#{person.photo}"
contentType="image/jpeg"
fileName="#{person.firstname}_#{person.lastname}.jpg"
status="personPhoto"
disposition="inline" />
<img src="cid:#{personPhoto.contentId}" />
You may be wondering what cid:#{...} does. Well, the IETF specified that by putting this as
the src for your image, the attachments will be looked at when trying to locate the image (the
Content-ID's must match) — magic!
You must declare the attachment before trying to access the status object.
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18.1.2. HTML/Text alternative part
Whilst most mail readers nowadays support HTML, some don't, so you can add a plain text
alternative to your email body:
<m:body>
<f:facet name="alternative">Sorry, your email reader can't show our fancy email,
please go to http://labs.jboss.com/jbossseam to explore Seam.</f:facet>
</m:body>
18.1.3. Multiple recipients
Often you'll want to send an email to a group of recipients (for example your users). All of the
recipient mail tags can be placed inside a <ui:repeat>:
<ui:repeat value="#{allUsers} var="user">
<m:to name="#{user.firstname} #{user.lastname}" address="#{user.emailAddress}" />
</ui:repeat>
18.1.4. Multiple messages
Sometimes, however, you need to send a slightly different message to each recipient (e.g. a
password reset). The best way to do this is to place the whole message inside a <ui:repeat>:
<ui:repeat value="#{people}" var="p">
<m:message>
<m:from name="#{person.firstname} #{person.lastname}">#{person.address}</m:from>
<m:to name="#{p.firstname}">#{p.address}</m:to>
...
</m:message>
</ui:repeat>
18.1.5. Templating
The mail templating example shows that facelets templating Just Works with the Seam mail tags.
Our template.xhtml contains:
<m:message>
<m:from name="Seam" address="[email protected]" />
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Internationalisation
<m:to name="#{person.firstname} #{person.lastname}">#{person.address}</m:to>
<m:subject>#{subject}</m:subject>
<m:body>
<html>
<body>
<ui:insert name="body">This is the default body, specified by the template.</ui:insert>
</body>
</html>
</m:body>
</m:message>
Our templating.xhtml contains:
<ui:param name="subject" value="Templating with Seam Mail"/>
<ui:define name="body">
<p>This example demonstrates that you can easily use <i>facelets templating</i> in email!</p>
</ui:define>
You can also use facelets source tags in your email, but you must place them in a jar in WEB-INF/
lib - referencing the .taglib.xml from web.xml isn't reliable when using Seam Mail (if you send
your mail asynchrounously Seam Mail doesn't have access to the full JSF or Servlet context, and
so doesn't know about web.xml configuration parameters).
If you do need more configure Facelets or JSF when sending mail, you'll need to override the
Renderer component and do the configuration programmatically - only for advanced users!
18.1.6. Internationalisation
Seam supports sending internationalised messages. By default, the encoding provided by JSF is
used, but this can be overridden on the template:
<m:message charset="UTF-8">
...
</m:message>
The body, subject and recipient (and from) name will be encoded. You'll need to make sure facelets
uses the correct charset for parsing your pages by setting encoding of the template:
<?xml version="1.0" encoding="UTF-8"?>
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18.1.7. Other Headers
Sometimes you'll want to add other headers to your email. Seam provides support for some (see
Section 18.5, “Tags”). For example, we can set the importance of the email, and ask for a read
receipt:
<m:message xmlns:m="http://jboss.com/products/seam/mail"
importance="low"
requestReadReceipt="true"/>
Otherise you can add any header to the message using the <m:header> tag:
<m:header name="X-Sent-From" value="JBoss Seam"/>
18.2. Receiving emails
If you are using EJB then you can use a MDB (Message Driven Bean) to receive email. JBoss
provides a JCA adaptor — mail-ra.rar — but the version distributed with JBoss AS has a
number of limitations (and isn't bundled in some versions) therefore we recommend using the
mail-ra.rar distributed with Seam is recommended (it's in the extras/ directory in the Seam
bundle). mail-ra.rar should be placed in $JBOSS_HOME/server/default/deploy; if the version
of JBoss AS you use already has this file, replace it.
You can configure it like this:
@MessageDriven(activationConfig={
@ActivationConfigProperty(propertyName="mailServer", propertyValue="localhost"),
@ActivationConfigProperty(propertyName="mailFolder", propertyValue="INBOX"),
@ActivationConfigProperty(propertyName="storeProtocol", propertyValue="pop3"),
@ActivationConfigProperty(propertyName="userName", propertyValue="seam"),
@ActivationConfigProperty(propertyName="password", propertyValue="seam")
})
@ResourceAdapter("mail-ra.rar")
@Name("mailListener")
public class MailListenerMDB implements MailListener {
@In(create=true)
private OrderProcessor orderProcessor;
public void onMessage(Message message) {
// Process the message
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Configuration
orderProcessor.process(message.getSubject());
}
}
Each message received will cause onMessage(Message message) to be called. Most Seam
annotations will work inside a MDB but you musn't access the persistence context.
You
can
find
more
information
Wiki.jsp?page=InboundJavaMail.
onmail-ra.rar
at
http://wiki.jboss.org/wiki/
If you aren't using JBoss AS you can still use mail-ra.rar or you may find your application server
includes a similar adapter.
18.3. Configuration
To include Email support in your application, include jboss-seam-mail.jar in your WEB-INF/
lib directory. If you are using JBoss AS there is no further configuration needed to use Seam's
email support. Otherwise you need to make sure you have the JavaMail API, an implementation
of the JavaMail API present (the API and impl used in JBoss AS are distributed with seam as
lib/mail.jar), and a copy of the Java Activation Framework (distributed with Seam as lib/
activation.jar.
The Seam Email module requires the use of Facelets as the view technology. Future versions
of the library may also support the use of JSP. Additionally, it requires the use of the seam-ui
package.
The mailSession component uses JavaMail to talk to a 'real' SMTP server.
18.3.1. mailSession
A JavaMail Session may be available via a JNDI lookup if you are working in an JEE environment
or you can use a Seam configured Session.
The mailSession component's properties are described in more detail in Section 28.8, “Mailrelated components”.
18.3.1.1. JNDI lookup in JBoss AS
The JBossAS deploy/mail-service.xml configures a JavaMail session binding into JNDI.
The default service configuration will need altering for your network. http://wiki.jboss.org/wiki/
Wiki.jsp?page=JavaMail describes the service in more detail.
<components xmlns="http://jboss.com/products/seam/components"
xmlns:core="http://jboss.com/products/seam/core"
xmlns:mail="http://jboss.com/products/seam/mail">
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<mail:mail-session session-jndi-name="java:/Mail"/>
</components>
Here we tell Seam to get the mail session bound to java:/Mail from JNDI.
18.3.1.2. Seam configured Session
A mail session can be configured via components.xml. Here we tell Seam to use
smtp.example.com as the smtp server:
<components xmlns="http://jboss.com/products/seam/components"
xmlns:core="http://jboss.com/products/seam/core"
xmlns:mail="http://jboss.com/products/seam/mail">
<mail:mail-session host="smtp.example.com"/>
</components>
18.4. Meldware
Seam's mail examples use Meldware (from buni.org [http://buni.org]) as a mail server. Meldware
is a groupware package that provides SMTP, POP3, IMAP, webmail, a shared calendar and an
graphical admin tool; it's written as a JEE application so can be deployed onto JBoss AS alongside
your Seam application.
The version of Meldware distributed with Seam (in the mail/buni-meldware folder) is specially
tailored for development - mailboxes, users and aliases (email addresses) are created every time
the application deploys. If you want to use Meldware in production you should install the latest
release from buni.org [http://buni.org].
To create mailboxes, users and aliases, you can use the meldware component:
<components xmlns="http://jboss.com/products/seam/components"
xmlns:core="http://jboss.com/products/seam/core"
xmlns:mail="http://jboss.com/products/seam/mail">
<mail:mail-session host="smtp.example.com"/>
<mail:meldware>
<mail:users>
<value>#{duke}</value>
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Tags
<value>#{root}</value>
</mail:users>
</mail:meldware>
<mail:meldware-user name="duke" username="duke" password="duke">
<mail:aliases>
<value>[email protected]</value>
<value>[email protected]</value>
</mail:aliases>
<mail:meldware-user name="root" username="root" password="root" administrator="true" />
</components>
Here we've created two users, duke, who has two email addresses and an administrator with the
username root.
18.5. Tags
Emails are generated using tags in the http://jboss.com/products/seam/mail namespace.
Documents should always have the message tag at the root of the message. The message tag
prepares Seam to generate an email.
The standard templating tags of facelets can be used as normal. Inside the body you can use
any JSF tag; if it requires access to external resources (stylesheets, javascript) then be sure to
set the urlBase.
<m:message>
Root tag of a mail message
• importance — low, normal or high. By default normal, this sets the importance of the mail
message.
• precedence — sets the precedence of the message (e.g. bulk).
• requestReadReceipt — by default false, if set, a read receipt request will be will be added,
with the read receipt being sent to the From: address.
• urlBase — If set, the value is prepended to the requestContextPath allowing you to use
components such as <h:graphicImage> in your emails.
<m:from>
Set's the From: address for the email. You can only have one of these per email.
• name — the name the email should come from.
• address — the email address the email should come from.
<m:replyTo>
Set's the Reply-to: address for the email. You can only have one of these per email.
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• address — the email address the email should come from.
<m:to>
Add a recipient to the email. Use multiple <m:to> tags for multiple recipients. This tag can be
safely placed inside a repeat tag such as <ui:repeat>.
• name — the name of the recipient.
• address — the email address of the recipient.
<m:cc>
Add a cc recipient to the email. Use multiple <m:cc> tags for multiple ccs. This tag can be
safely placed inside a iterator tag such as <ui:repeat>.
• name — the name of the recipient.
• address — the email address of the recipient.
<m:bcc>
Add a bcc recipient to the email. Use multiple <m:bcc> tags for multiple bccs. This tag can be
safely placed inside a repeat tag such as <ui:repeat>.
• name — the name of the recipient.
• address — the email address of the recipient.
<m:header>
Add a header to the email (e.g. X-Sent-From: JBoss Seam)
• name — The name of the header to add (e.g. X-Sent-From).
• value — The value of the header to add (e.g. JBoss Seam).
<m:attachment>
Add an attachment to the email.
• value — The file to attach:
• String — A String is interpreted as a path to file within the classpath
• java.io.File — An EL expression can reference a File object
• java.net.URL — An EL expression can reference a URL object
• java.io.InputStream — An EL expression can reference an InputStream. In this case
both a fileName and a contentType must be specified.
• byte[] — An EL expression can reference an byte[]. In this case both a fileName and
a contentType must be specified.
If the value attribute is ommitted:
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Tags
• If this tag contains a <p:document> tag, the document described will be generated and
attached to the email. A fileName should be specfied.
• If this tag contains other JSF tags a HTML document will be generated from them and
attached to the email. A fileName should be specfied.
• fileName — Specify the file name to use for the attached file.
• contentType — Specify the MIME type of the attached file
<m:subject>
Set's the subject for the email.
<m:body>
Set's the body for the email. Supports an alternative facet which, if an HTML email is
generated can contain alternative text for a mail reader which doesn't support html.
• type — If set to plain then a plain text email will be generated otherwise an HTML email
is generated.
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Chapter 19.
Asynchronicity and messaging
Seam makes it very easy to perform work asynchronously from a web request. When most people
think of asynchronicity in Java EE, they think of using JMS. This is certainly one way to approach
the problem in Seam, and is the right way when you have strict and well-defined quality of service
requirements. Seam makes it easy to send and recieve JMS messages using Seam components.
But for many usecases, JMS is overkill. Seam layers a simple asynchronous method and event
facility over your choice of dispatchers:
• java.util.concurrent.ScheduledThreadPoolExecutor (by default)
• the EJB timer service (for EJB 3.0 environments)
• Quartz
19.1. Asynchronicity
Asynchronous events and method calls have the same quality of service expectations
as the underlying dispatcher mechanism. The default dispatcher, based upon a
ScheduledThreadPoolExecutor performs efficiently but provides no support for persistent
asynchronous tasks, and hence no guarantee that a task will ever actually be executed. If you're
working in an environment that supports EJB 3.0, and add the following line to components.xml:
<async:timer-service-dispatcher/>
then your asynchronous tasks will be processed by the container's EJB timer service. If you're not
familiar with the Timer service, don't worry, you don't need to interact with it directly if you want
to use asynchronous methods in Seam. The important thing to know is that any good EJB 3.0
implementation will have the option of using persistent timers, which gives some guarantee that
the tasks will eventually be processed.
Another alternative is to use the open source Quartz library to manage asynchronous method.
You need to bundle the Quartz library JAR (found in the lib directory) in your EAR and declare
it as a Java module in application.xml. In addition, you need to add the following line to
components.xml to install the Quartz dispatcher.
<async:quartz-dispatcher/>
The Seam API for the default ScheduledThreadPoolExecutor, the EJB3 Timer, and the
Quartz Scheduler are largely the same. They can just "plug and play" by adding a line to
components.xml.
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19.1.1. Asynchronous methods
In simplest form, an asynchronous call just lets a method call be processed asynchronously (in a
different thread) from the caller. We usually use an asynchronous call when we want to return an
immediate response to the client, and let some expensive work be processed in the background.
This pattern works very well in applications which use AJAX, where the client can automatically
poll the server for the result of the work.
For EJB components, we annotate the local interface to specify that a method is processed
asynchronously.
@Local
public interface PaymentHandler
{
@Asynchronous
public void processPayment(Payment payment);
}
(For JavaBean components we can annotate the component implementation class if we like.)
The use of asynchronicity is transparent to the bean class:
@Stateless
@Name("paymentHandler")
public class PaymentHandlerBean implements PaymentHandler
{
public void processPayment(Payment payment)
{
//do some work!
}
}
And also transparent to the client:
@Stateful
@Name("paymentAction")
public class CreatePaymentAction
{
@In(create=true) PaymentHandler paymentHandler;
@In Bill bill;
public String pay()
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Asynchronous methods
{
paymentHandler.processPayment( new Payment(bill) );
return "success";
}
}
The asynchronous method is processed in a completely new event context and does not have
access to the session or conversation context state of the caller. However, the business process
context is propagated.
Asynchronous method calls may be scheduled for later execution using the @Duration,
@Expiration and @IntervalDuration annotations.
@Local
public interface PaymentHandler
{
@Asynchronous
public void processScheduledPayment(Payment payment, @Expiration Date date);
@Asynchronous
public void processRecurringPayment(Payment payment,
@Expiration Date date,
@IntervalDuration Long interval)'
}
@Stateful
@Name("paymentAction")
public class CreatePaymentAction
{
@In(create=true) PaymentHandler paymentHandler;
@In Bill bill;
public String schedulePayment()
{
paymentHandler.processScheduledPayment( new Payment(bill), bill.getDueDate() );
return "success";
}
public String scheduleRecurringPayment()
{
paymentHandler.processRecurringPayment( new Payment(bill), bill.getDueDate(),
ONE_MONTH );
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return "success";
}
}
Both client and server may access the Timer object associated with the invocation. The Timer
object shown below is the EJB3 timer when you use the EJB3 dispatcher. For the default
ScheduledThreadPoolExecutor, the returned object is Future from the JDK. For the Quartz
dispatcher, it returns QuartzTriggerHandle, which we will discuss in the next section.
@Local
public interface PaymentHandler
{
@Asynchronous
public Timer processScheduledPayment(Payment payment, @Expiration Date date);
}
@Stateless
@Name("paymentHandler")
public class PaymentHandlerBean implements PaymentHandler
{
@In Timer timer;
public Timer processScheduledPayment(Payment payment, @Expiration Date date)
{
//do some work!
return timer; //note that return value is completely ignored
}
}
@Stateful
@Name("paymentAction")
public class CreatePaymentAction
{
@In(create=true) PaymentHandler paymentHandler;
@In Bill bill;
public String schedulePayment()
{
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Asynchronous methods with the Quartz
Dispatcher
Timer timer = paymentHandler.processScheduledPayment( new Payment(bill),
bill.getDueDate() );
return "success";
}
}
Asynchronous methods cannot return any other value to the caller.
19.1.2. Asynchronous methods with the Quartz Dispatcher
The Quartz dispatcher (see earlier on how to install it) allows you to use the @Asynchronous,
@Duration, @Expiration, and @IntervalDuration annotations as above. But it has some
powerful additional features. The Quartz dispatcher supports three new annotations.
The @FinalExpiration annotation specifies an end date for the recurring task.
// Defines the method in the "processor" component
@Asynchronous
public QuartzTriggerHandle schedulePayment(@Expiration Date when,
@IntervalDuration Long interval,
@FinalExpiration Date endDate,
Payment payment)
{
// do the repeating or long running task until endDate
}
... ...
// Schedule the task in the business logic processing code
// Starts now, repeats every hour, and ends on May 10th, 2010
Calendar cal = Calendar.getInstance ();
cal.set (2010, Calendar.MAY, 10);
processor.schedulePayment(new Date(), 60*60*1000, cal.getTime(), payment);
Note that the method returns the QuartzTriggerHandle object, which you can use later to stop,
pause, and resume the scheduler. The QuartzTriggerHandle object is serializable, so you can
save it into the database if you need to keep it around for extended period of time.
QuartzTriggerHandle handle =
processor.schedulePayment(payment.getPaymentDate(),
payment.getPaymentCron(),
payment);
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Chapter 19. Asynchronicity an...
payment.setQuartzTriggerHandle( handle );
// Save payment to DB
// later ...
// Retrieve payment from DB
// Cancel the remaining scheduled tasks
payment.getQuartzTriggerHandle().cancel();
The @IntervalCron annotation supports Unix cron job syntax for task scheduling. For instance,
the following asynchronous method runs at 2:10pm and at 2:44pm every Wednesday in the month
of March.
// Define the method
@Asynchronous
public QuartzTriggerHandle schedulePayment(@Expiration Date when,
@IntervalCron String cron,
Payment payment)
{
// do the repeating or long running task
}
... ...
// Schedule the task in the business logic processing code
QuartzTriggerHandle handle =
processor.schedulePayment(new Date(), "0 10,44 14 ? 3 WED", payment);
The @IntervalBusinessDay annotation supports invocation on the "nth Business Day" scenario.
For instance, the following asynchronous method runs at 14:00 on the 2nd business day of each
month. By default, it excludes all weekends and US federal holidays until 2010 from the business
days.
// Define the method
@Asynchronous
public QuartzTriggerHandle schedulePayment(@Expiration Date when,
@IntervalBusinessDay NthBusinessDay nth,
Payment payment)
{
// do the repeating or long running task
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Asynchronous methods with the Quartz
Dispatcher
}
... ...
// Schedule the task in the business logic processing code
QuartzTriggerHandle handle =
processor.schedulePayment(new Date(),
new NthBusinessDay(2, "14:00", WEEKLY), payment);
The NthBusinessDay object contains the configuration of the invocation trigger. You can specify
more holidays (e.g., company holidays, non-US holidays etc.) via the additionalHolidays
property.
public class NthBusinessDay implements Serializable
{
int n;
String fireAtTime;
List <Date> additionalHolidays;
BusinessDayIntervalType interval;
boolean excludeWeekends;
boolean excludeUsFederalHolidays;
public enum BusinessDayIntervalType { WEEKLY, MONTHLY, YEARLY }
public NthBusinessDay ()
{
n = 1;
fireAtTime = "12:00";
additionalHolidays = new ArrayList <Date> ();
interval = BusinessDayIntervalType.WEEKLY;
excludeWeekends = true;
excludeUsFederalHolidays = true;
}
... ...
}
The @IntervalDuration, @IntervalCron, and @IntervalNthBusinessDay annotations are
mutually exclusive. If they are used in the same method, a RuntimeException will be thrown.
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19.1.3. Asynchronous events
Component-driven events may also be asynchronous. To raise an event for asynchronous
processing, simply call the raiseAsynchronousEvent() method of the Events class. To
schedule a timed event, call the raiseTimedEvent() method, passing a schedule object (for the
default dispatcher or timer service dispatcher, use TimerSchedule). Components may observe
asynchronous events in the usual way, but remember that only the business process context is
propagated to the asynchronous thread.
19.2. Messaging in Seam
Seam makes it easy to send and receive JMS messages to and from Seam components.
19.2.1. Configuration
To configure Seam's infrastructure for sending JMS messages, you need to tell Seam about
any topics and queues you want to send messages to, and also tell Seam where to find the
QueueConnectionFactory and/or TopicConnectionFactory.
Seam defaults to using UIL2ConnectionFactory which is the usual connection
factory for use with JBossMQ. If you are using some other JMS provider, you
need to set one or both of queueConnection.queueConnectionFactoryJndiName and
topicConnection.topicConnectionFactoryJndiName in seam.properties, web.xml or
components.xml.
You also need to list topics and queues in components.xml to install Seam managed
TopicPublishers and QueueSenders:
<jms:managed-topic-publisher name="stockTickerPublisher"
auto-create="true"
topic-jndi-name="topic/stockTickerTopic"/>
<jms:managed-queue-sender name="paymentQueueSender"
auto-create="true"
queue-jndi-name="queue/paymentQueue"/>
19.2.2. Sending messages
Now, you can inject a JMS TopicPublisher and TopicSession into any component:
@In
private TopicPublisher stockTickerPublisher;
@In
private TopicSession topicSession;
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Receiving messages using a message-driven
bean
public void publish(StockPrice price) {
try
{
stockTickerPublisher.publish( topicSession.createObjectMessage(price) );
}
catch (Exception ex)
{
throw new RuntimeException(ex);
}
}
Or, for working with a queue:
@In
private QueueSender paymentQueueSender;
@In
private QueueSession queueSession;
public void publish(Payment payment) {
try
{
paymentQueueSender.send( queueSession.createObjectMessage(payment) );
}
catch (Exception ex)
{
throw new RuntimeException(ex);
}
}
19.2.3. Receiving messages using a message-driven bean
You can process messages using any EJB3 message driven bean. Message-driven beans may
even be Seam components, in which case it is possible to inject other event and application
scoped Seam components.
19.2.4. Receiving messages in the client
Seam Remoting lets you subscribe to a JMS topic from client-side JavaScript. This is described
in Chapter 22, Remoting.
305
306
Chapter 20.
Caching
In almost all enterprise applications, the database is the primary bottleneck, and the least scalable
tier of the runtime environment. People from a PHP/Ruby environment will try to tell you that
so-called "shared nothing" architectures scale well. While that may be literally true, I don't know of
many interesting multi-user applications which can be implemented with no sharing of resources
between different nodes of the cluster. What these silly people are really thinking of is a "share
nothing except for the database" architecture. Of course, sharing the database is the primary
problem with scaling a multi-user application—so the claim that this architecture is highly scalable
is absurd, and tells you a lot about the kind of applications that these folks spend most of their
time working on.
Almost anything we can possibly do to share the database less often is worth doing.
This calls for a cache. Well, not just one cache. A well designed Seam application will feature a
rich, multi-layered caching strategy that impacts every layer of the application:
• The database, of course, has its own cache. This is super-important, but can't scale like a cache
in the application tier.
• Your ORM solution (Hibernate, or some other JPA implementation) has a second-level cache
of data from the database. This is a very powerful capability, but is often misused. In a clustered
environment, keeping the data in the cache transactionally consistent across the whole cluster,
and with the database, is quite expensive. It makes most sense for data which is shared between
many users, and is updated rarely. In traditional stateless architectures, people often try to use
the second-level cache for conversational state. This is always bad, and is especially wrong
in Seam.
• The Seam conversation context is a cache of conversational state. Components you put into
the conversation context can hold and cache state relating to the current user interaction.
• In particular, the Seam-managed persistence context (or an extended EJB container-managed
persistence context associated with a conversation-scoped stateful session bean) acts as a
cache of data that has been read in the current conversation. This cache tends to have a
pretty high hitrate! Seam optimizes the replication of Seam-managed persistence contexts
in a clustered environment, and there is no requirement for transactional consistency with
the database (optimistic locking is sufficient) so you don't need to worry too much about the
performance implications of this cache, unless you read thousands of objects into a single
persistence context.
• The application can cache non-transactional state in the Seam application context. State kept
in the application context is of course not visible to other nodes in the cluster.
• The application can cache transactional state using the Seam pojoCache component, which
integrates JBossCache into the Seam environment. This state will be visible to other nodes if
you run JBoss cache in a clustered mode.
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Chapter 20. Caching
• Finally, Seam lets you cache rendered fragments of a JSF page. Unlike the ORM second-level
cache, this cache is not automatically invalidated when data changes, so you need to write
application code to perform explicit invalidation, or set appropriate expiration policies.
For more information about the second-level cache, you'll need to refer to the documentation of
your ORM solution, since this is an extremely complex topic. In this section we'll discuss the use
of JBossCache directly, via the pojoCache component, or as the page fragment cache, via the
<s:cache> control.
20.1. Using JBossCache in Seam
The built-in pojoCache component manages an instance of org.jboss.cache.aop.PojoCache.
You can safely put any immutable Java object in the cache, and it will be replicated across the
cluster (assuming that replication is enabled). If you want to keep mutable objects in the cache,
you'll need to run the JBossCache bytecode preprocessor to ensure that changes to the objects
will be automatically detected and replicated.
To use pojoCache, all you need to do is put the JBossCache jars in the classpath, and provide a
resource named treecache.xml with an appropriate cache configuration. JBossCache has many
scary and confusing configuration settings, so we won't discuss them here. Please refer to the
JBossCache documentation for more information.
You can find a sample treecache.xml in examples/blog/resources/treecache.xml.
For an EAR depoyment of Seam, we recommend that the JBossCache jars and configuration
go directly into the EAR. Make sure you place both jboss-cache.jar and jgroups.jar in your
EAR's lib folder.
Now you can inject the cache into any Seam component:
@Name("chatroom")
public class Chatroom {
@In PojoCache pojoCache;
public void join(String username) {
try
{
Set<String> userList = (Set<String>) pojoCache.get("chatroom", "userList");
if (userList==null)
{
userList = new HashSet<String>();
pojoCache.put("chatroom", "userList", userList);
}
userList.put(username);
}
catch (CacheException ce)
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Page fragment caching
{
throw new RuntimeException(ce);
}
}
}
If you want to have multiple JBossCache configurations in your application, use components.xml:
<core:pojo-cache name="myCache" cfg-resource-name="myown/cache.xml"/>
20.2. Page fragment caching
The most interesting user of JBossCache is the <s:cache> tag, Seam's solution to the problem
of page fragment caching in JSF. <s:cache> uses pojoCache internally, so you need to follow
the steps listed above before you can use it. (Put the jars in the EAR, wade through the scary
configuration options, etc.)
<s:cache> is used for caching some rendered content which changes rarely. For example, the
welcome page of our blog displays the recent blog entries:
<s:cache key="recentEntries-#{blog.id}" region="welcomePageFragments">
<h:dataTable value="#{blog.recentEntries}" var="blogEntry">
<h:column>
<h3>#{blogEntry.title}</h3>
<div>
<s:formattedText value="#{blogEntry.body}"/>
</div>
</h:column>
</h:dataTable>
</s:cache>
The key let's you have multiple cached versions of each page fragment. In this case, there is one
cached version per blog. The region determines the JBossCache node that all version will be
stored in. Different nodes may have different expiry policies. (That's the stuff you set up using the
aforementioned scary configuration options.)
Of course, the big problem with <s:cache> is that it is too stupid to know when the underlying
data changes (for example, when the blogger posts a new entry). So you need to evict the cached
fragment manually:
public void post() {
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Chapter 20. Caching
...
entityManager.persist(blogEntry);
pojoCache.remove("welcomePageFragments", "recentEntries-" + blog.getId() );
}
Alternatively, if it is not critical that changes are immediately visible to the user, you could set a
short expiry time on the JbossCache node.
310
Chapter 21.
Web Services
Seam integrates with JBossWS to allow standard JEE web services to take full advantage of
Seam's contextual framework, including support for conversational web services. This chapter
walks through the steps required to allow web services to run within a Seam environment.
21.1. Configuration and Packaging
To allow Seam to intercept web service requests so that the necessary Seam
contexts can be created for the request, a special SOAP handler must be configured;
org.jboss.seam.webservice.SOAPRequestHandler is a SOAPHandler implementation that
does the work of managing Seam's lifecycle during the scope of a web service request.
A special configuration file, standard-jaxws-endpoint-config.xml should be placed into the
META-INF directory of the jar file that contains the web service classes. This file contains the
following SOAP handler configuration:
<jaxws-config xmlns="urn:jboss:jaxws-config:2.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:javaee="http://java.sun.com/xml/ns/javaee"
xsi:schemaLocation="urn:jboss:jaxws-config:2.0 jaxws-config_2_0.xsd">
<endpoint-config>
<config-name>Seam WebService Endpoint</config-name>
<pre-handler-chains>
<javaee:handler-chain>
<javaee:protocol-bindings>##SOAP11_HTTP</javaee:protocol-bindings>
<javaee:handler>
<javaee:handler-name>SOAP Request Handler</javaee:handler-name>
<javaee:handler-class>org.jboss.seam.webservice.SOAPRequestHandler</
javaee:handler-class>
</javaee:handler>
</javaee:handler-chain>
</pre-handler-chains>
</endpoint-config>
</jaxws-config>
21.2. Conversational Web Services
So how are conversations propagated between web service requests? Seam uses a SOAP header
element present in both the SOAP request and response messages to carry the conversation ID
from the consumer to the service, and back again. Here's an example of a web service request
that contains a conversation ID:
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Chapter 21. Web Services
<soapenv:Envelope xmlns:soapenv="http://schemas.xmlsoap.org/soap/envelope/"
xmlns:seam="http://seambay.example.seam.jboss.org/">
<soapenv:Header>
<seam:conversationId
seam:conversationId>
</soapenv:Header>
<soapenv:Body>
<seam:confirmAuction/>
</soapenv:Body>
</soapenv:Envelope>
xmlns:seam='http://www.jboss.org/seam/webservice'>2</
As you can see in the above SOAP message, there is a conversationId element within the
SOAP header that contains the conversation ID for the request, in this case 2. Unfortunately,
because web services may be consumed by a variety of web service clients written in a variety of
languages, it is up to the developer to implement conversation ID propagation between individual
web services that are intended to be used within the scope of a single conversation.
An important thing to note is that the conversationId header element must be qualified with a
namespace of http://www.jboss.org/seam/webservice, otherwise Seam will not be able to
read the conversation ID from the request. Here's an example of a response to the above request
message:
<env:Envelope xmlns:env='http://schemas.xmlsoap.org/soap/envelope/'>
<env:Header>
<seam:conversationId xmlns:seam='http://www.jboss.org/seam/webservice'>2</
seam:conversationId>
</env:Header>
<env:Body>
<confirmAuctionResponse xmlns="http://seambay.example.seam.jboss.org/"/>
</env:Body>
</env:Envelope>
As you can see, the response message contains the same conversationId element as the
request.
21.2.1. A Recommended Strategy
As web services must be implemented as either a stateless session bean or POJO, it is
recommended that for conversational web services, the web service acts as a facade to a
conversational Seam component.
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An example web service
If the web service is written as a stateless session bean, then it is also possible to make it a Seam
component by giving it a @Name. Doing this allows Seam's bijection (and other) features to be used
in the web service class itself.
21.3. An example web service
Let's walk through an example web service. The code in this section all comes from the seamBay
example application in Seam's /examples directory, and follows the recommended strategy as
described in the previous section. Let's first take a look at the web service class and one of its
web service methods:
@Stateless
@WebService(name = "AuctionService", serviceName = "AuctionService")
public class AuctionService implements AuctionServiceRemote
{
@WebMethod
public boolean login(String username, String password)
{
Identity.instance().setUsername(username);
Identity.instance().setPassword(password);
Identity.instance().login();
return Identity.instance().isLoggedIn();
}
// snip
}
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As you can see, our web service is a stateless session bean, and is annotated using the JWS
annotations from the javax.jws package, as defined by JSR-181. The @WebService annotation
tells the container that this class implements a web service, and the @WebMethod annotation on
the login() method identifies the method as a web service method. The name and serviceName
attributes in the @WebService annotation are optional.
As is required by the specification, each method that is to be exposed as a web service method
must also be declared in the remote interface of the web service class (when the web service
is a stateless session bean). In the above example, the AuctionServiceRemote interface must
declare the login() method as it is annotated as a @WebMethod.
As you can see in the above code, the web service implements a login() method that delegates
to Seam's built-in Identity component. In keeping with our recommended strategy, the web
service is written as a simple facade, passing off the real work to a Seam component. This allows
for the greatest reuse of business logic between web services and other clients.
Let's look at another example. This web service method begins a new conversation by delegating
to the AuctionAction.createAuction() method:
@WebMethod
public void createAuction(String title, String description, int categoryId)
{
AuctionAction action = (AuctionAction) Component.getInstance(AuctionAction.class, true);
action.createAuction();
action.setDetails(title, description, categoryId);
}
And here's the code from AuctionAction:
@Begin
public void createAuction()
{
auction = new Auction();
auction.setAccount(authenticatedAccount);
auction.setStatus(Auction.STATUS_UNLISTED);
durationDays = DEFAULT_AUCTION_DURATION;
}
From this we can see how web services can participate in long running conversations, by acting
as a facade and delegating the real work to a conversational Seam component.
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Remoting
Seam provides a convenient method of remotely accessing components from a web page, using
AJAX (Asynchronous Javascript and XML). The framework for this functionality is provided with
almost no up-front development effort - your components only require simple annotating to
become accessible via AJAX. This chapter describes the steps required to build an AJAX-enabled
web page, then goes on to explain the features of the Seam Remoting framework in more detail.
22.1. Configuration
To use remoting, the Seam Resource servlet must first be configured in your web.xml file:
<servlet>
<servlet-name>Seam Resource Servlet</servlet-name>
<servlet-class>org.jboss.seam.servlet.SeamResourceServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Seam Resource Servlet</servlet-name>
<url-pattern>/seam/resource/*</url-pattern>
</servlet-mapping>
The next step is to import the necessary Javascript into your web page. There are a minimum of
two scripts that must be imported. The first one contains all the client-side framework code that
enables remoting functionality:
<script type="text/javascript" src="seam/resource/remoting/resource/remote.js"></script>
The second script contains the stubs and type definitions for the components you wish to call.
It is generated dynamically based on the local interface of your components, and includes type
definitions for all of the classes that can be used to call the remotable methods of the interface.
The name of the script reflects the name of your component. For example, if you have a stateless
session bean annotated with @Name("customerAction"), then your script tag should look like
this:
<script type="text/javascript"
src="seam/resource/remoting/interface.js?customerAction"></script>
If you wish to access more than one component from the same page, then include them all as
parameters of your script tag:
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<script type="text/javascript"
src="seam/resource/remoting/interface.js?customerAction&accountAction"></script>
Alternatively, you may use the s:remote tag to import the required Javascript. Separate each
component or class name you wish to import with a comma:
<s:remote include="customerAction,accountAction"/>
22.2. The "Seam" object
Client-side interaction with your components is all performed via the Seam Javascript object.
This object is defined in remote.js, and you'll be using it to make asynchronous calls against
your component. It is split into two areas of functionality; Seam.Component contains methods for
working with components and Seam.Remoting contains methods for executing remote requests.
The easiest way to become familiar with this object is to start with a simple example.
22.2.1. A Hello World example
Let's step through a simple example to see how the Seam object works. First of all, let's create a
new Seam component called helloAction.
@Stateless
@Name("helloAction")
public class HelloAction implements HelloLocal {
public String sayHello(String name) {
return "Hello, " + name;
}
}
You also need to create a local interface for our new component - take special note of the
@WebRemote annotation, as it's required to make our method accessible via remoting:
@Local
public interface HelloLocal {
@WebRemote
public String sayHello(String name);
}
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A Hello World example
That's all the server-side code we need to write. Now for our web page - create a new page and
import the helloAction component:
<s:remote include="helloAction"/>
To make this a fully interactive user experience, let's add a button to our page:
<button onclick="javascript:sayHello()">Say Hello</button>
We'll also need to add some more script to make our button actually do something when it's clicked:
<script type="text/javascript">
//<![CDATA[
function sayHello() {
var name = prompt("What is your name?");
Seam.Component.getInstance("helloAction").sayHello(name, sayHelloCallback);
}
function sayHelloCallback(result) {
alert(result);
}
// ]]>
</script>
We're done! Deploy your application and browse to your page. Click the button, and enter a
name when prompted. A message box will display the hello message confirming that the call was
successful. If you want to save some time, you'll find the full source code for this Hello World
example in Seam's /examples/remoting/helloworld directory.
So what does the code of our script actually do? Let's break it down into smaller pieces. To start
with, you can see from the Javascript code listing that we have implemented two methods - the first
method is responsible for prompting the user for their name and then making a remote request.
Take a look at the following line:
Seam.Component.getInstance("helloAction").sayHello(name, sayHelloCallback);
The first section of this line, Seam.Component.getInstance("helloAction") returns a proxy,
or "stub" for our helloAction component. We can invoke the methods of our component
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against this stub, which is exactly what happens with the remainder of the line: sayHello(name,
sayHelloCallback);.
What this line of code in its completeness does, is invoke the sayHello method of our component,
passing in name as a parameter. The second parameter, sayHelloCallback isn't a parameter
of our component's sayHello method, instead it tells the Seam Remoting framework that once
it receives the response to our request, it should pass it to the sayHelloCallback Javascript
method. This callback parameter is entirely optional, so feel free to leave it out if you're calling a
method with a void return type or if you don't care about the result.
The sayHelloCallback method, once receiving the response to our remote request then pops
up an alert message displaying the result of our method call.
22.2.2. Seam.Component
The Seam.Component Javascript object provides a number of client-side methods for working
with your Seam components. The two main methods, newInstance() and getInstance() are
documented in the following sections however their main difference is that newInstance() will
always create a new instance of a component type, and getInstance() will return a singleton
instance.
22.2.2.1. Seam.Component.newInstance()
Use this method to create a new instance of an entity or Javabean component. The object
returned by this method will have the same getter/setter methods as its server-side counterpart,
or alternatively if you wish you can access its fields directly. Take the following Seam entity
component for example:
@Name("customer")
@Entity
public class Customer implements Serializable
{
private Integer customerId;
private String firstName;
private String lastName;
@Column public Integer getCustomerId() {
return customerId;
}
public void setCustomerId(Integer customerId} {
this.customerId = customerId;
}
@Column public String getFirstName() {
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Seam.Component
return firstName;
}
public void setFirstName(String firstName) {
this.firstName = firstName;
}
@Column public String getLastName() {
return lastName;
}
public void setLastName(String lastName) {
this.lastName = lastName;
}
}
To create a client-side Customer you would write the following code:
var customer = Seam.Component.newInstance("customer");
Then from here you can set the fields of the customer object:
customer.setFirstName("John");
// Or you can set the fields directly
customer.lastName = "Smith";
22.2.2.2. Seam.Component.getInstance()
The getInstance() method is used to get a reference to a Seam session bean component stub,
which can then be used to remotely execute methods against your component. This method
returns a singleton for the specified component, so calling it twice in a row with the same
component name will return the same instance of the component.
To continue our example from before, if we have created a new customer and we now wish to
save it, we would pass it to the saveCustomer() method of our customerAction component:
Seam.Component.getInstance("customerAction").saveCustomer(customer);
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22.2.2.3. Seam.Component.getComponentName()
Passing an object into this method will return its component name if it is a component, or null
if it is not.
if (Seam.Component.getComponentName(instance) == "customer")
alert("Customer");
else if (Seam.Component.getComponentName(instance) == "staff")
alert("Staff member");
22.2.3. Seam.Remoting
Most of the client side functionality for Seam Remoting is contained within the Seam.Remoting
object. While you shouldn't need to directly call most of its methods, there are a couple of important
ones worth mentioning.
22.2.3.1. Seam.Remoting.createType()
If your application contains or uses Javabean classes that aren't Seam components, you may
need to create these types on the client side to pass as parameters into your component method.
Use the createType() method to create an instance of your type. Pass in the fully qualified Java
class name as a parameter:
var widget = Seam.Remoting.createType("com.acme.widgets.MyWidget");
22.2.3.2. Seam.Remoting.getTypeName()
This method is the equivalent of Seam.Component.getComponentName() but for non-component
types. It will return the name of the type for an object instance, or null if the type is not known.
The name is the fully qualified name of the type's Java class.
22.3. Evaluating EL Expressions
Seam Remoting also supports the evaluation of EL expressions, which provides another
convenient method for retrieving data from the server. Using the Seam.Remoting.eval() function,
an EL expression can be remotely evaluated on the server and the resulting value returned
to a client-side callback method. This function accepts two parameters, the first being the EL
expression to evaluate, and the second being the callback method to invoke with the value of the
expression. Here's an example:
function customersCallback(customers) {
for (var i = 0; i < customers.length; i++) {
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Client Interfaces
alert("Got customer: " + customers[i].getName());
}
}
Seam.Remoting.eval("#{customers}", customersCallback);
In this example, the expression #{customers} is evaluated by Seam, and the value of the
expression (in this case a list of Customer objects) is returned to the customersCallback()
method. It is important to remember that the objects returned this way must have their types
imported (via s:remote) to be able to work with them in Javascript. So to work with a list of
customer objects, it is required to import the customer type:
<s:remote include="customer"/>
22.4. Client Interfaces
In the configuration section above, the interface, or "stub" for our component is imported into our
page either via seam/resource/remoting/interface.js: or using the s:remote tag:
<script type="text/javascript"
src="seam/resource/remoting/interface.js?customerAction"></script>
<s:remote include="customerAction"/>
By including this script in our page, the interface definitions for our component, plus any other
components or types that are required to execute the methods of our component are generated
and made available for the remoting framework to use.
There are two types of client stub that can be generated, "executable" stubs and "type" stubs.
Executable stubs are behavioural, and are used to execute methods against your session bean
components, while type stubs contain state and represent the types that can be passed in as
parameters or returned as a result.
The type of client stub that is generated depends on the type of your Seam component. If the
component is a session bean, then an executable stub will be generated, otherwise if it's an
entity or JavaBean, then a type stub will be generated. There is one exception to this rule; if your
component is a JavaBean (ie it is not a session bean nor an entity bean) and any of its methods
are annotated with @WebRemote, then an executable stub will be generated for it instead of a
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type stub. This allows you to use remoting to call methods of your JavaBean components in a
non-EJB environment where you don't have access to session beans.
22.5. The Context
The Seam Remoting Context contains additional information which is sent and received as part
of a remoting request/response cycle. At this stage it only contains the conversation ID but may
be expanded in the future.
22.5.1. Setting and reading the Conversation ID
If you intend on using remote calls within the scope of a conversation then
you need to be able to read or set the conversation ID in the Seam
Remoting Context. To read the conversation ID after making a remote request call
Seam.Remoting.getContext().getConversationId(). To set the conversation ID before
making a request, call Seam.Remoting.getContext().setConversationId().
If
the
conversation
ID
hasn't
been
explicitly
set
with
Seam.Remoting.getContext().setConversationId(), then it will be automatically assigned
the first valid conversation ID that is returned by any remoting call. If you are working with multiple
conversations within your page, then you may need to explicitly set the conversation ID before
each call. If you are working with just a single conversation, then you don't need to do anything
special.
22.5.2. Remote calls within the current conversation scope
In some circumstances it may be required to make a remote call within the scope of the current
view's conversation. To do this, you must explicitly set the conversation ID to that of the view
before making the remote call. This small snippet of JavaScript will set the conversation ID that
is used for remoting calls to the current view's conversation ID:
Seam.Remoting.getContext().setConversationId( #{conversation.id} );
22.6. Batch Requests
Seam Remoting allows multiple component calls to be executed within a single request. It is
recommended that this feature is used wherever it is appropriate to reduce network traffic.
The method Seam.Remoting.startBatch() will start a new batch, and any component calls
executed after starting a batch are queued, rather than being sent immediately. When all the
desired component calls have been added to the batch, the Seam.Remoting.executeBatch()
method will send a single request containing all of the queued calls to the server, where they will
be executed in order. After the calls have been executed, a single response containining all return
values will be returned to the client and the callback functions (if provided) triggered in the same
order as execution.
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Working with Data types
If you start a new batch via the startBatch() method but then decide you don't want to send
it, the Seam.Remoting.cancelBatch() method will discard any calls that were queued and exit
the batch mode.
To see an example of a batch being used, take a look at /examples/remoting/chatroom.
22.7. Working with Data types
22.7.1. Primitives / Basic Types
This section describes the support for basic data types. On the server side these values are
generally compatible with either their primitive type or their corresponding wrapper class.
22.7.1.1. String
Simply use Javascript String objects when setting String parameter values.
22.7.1.2. Number
There is support for all number types supported by Java. On the client side, number values are
always serialized as their String representation and then on the server side they are converted
to the correct destination type. Conversion into either a primitive or wrapper type is supported for
Byte, Double, Float, Integer, Long and Short types.
22.7.1.3. Boolean
Booleans are represented client side by Javascript Boolean values, and server side by a Java
boolean.
22.7.2. JavaBeans
In general these will be either Seam entity or JavaBean components, or some other noncomponent class. Use the appropriate method (either Seam.Component.newInstance() for Seam
components or Seam.Remoting.createType() for everything else) to create a new instance of
the object.
It is important to note that only objects that are created by either of these two methods should
be used as parameter values, where the parameter is not one of the other valid types mentioned
anywhere else in this section. In some situations you may have a component method where the
exact parameter type cannot be determined, such as:
@Name("myAction")
public class MyAction implements MyActionLocal {
public void doSomethingWithObject(Object obj) {
// code
}
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}
In this case you might want to pass in an instance of your myWidget component, however the
interface for myAction won't include myWidget as it is not directly referenced by any of its methods.
To get around this, MyWidget needs to be explicitly imported:
<s:remote include="myAction,myWidget"/>
This
will
then
allow
a
object
to
be
created
with
which
can
then
be
passed
to
myWidget
Seam.Component.newInstance("myWidget"),
myAction.doSomethingWithObject().
22.7.3. Dates and Times
Date values are serialized into a String representation that is accurate to the millisecond. On the
client side, use a Javascript Date object to work with date values. On the server side, use any
java.util.Date (or descendent, such as java.sql.Date or java.sql.Timestamp class.
22.7.4. Enums
On the client side, enums are treated the same as Strings. When setting the value for an enum
parameter, simply use the String representation of the enum. Take the following component as
an example:
@Name("paintAction")
public class paintAction implements paintLocal {
public enum Color {red, green, blue, yellow, orange, purple};
public void paint(Color color) {
// code
}
}
To call the paint() method with the color red, pass the parameter value as a String literal:
Seam.Component.getInstance("paintAction").paint("red");
The inverse is also true - that is, if a component method returns an enum parameter (or contains
an enum field anywhere in the returned object graph) then on the client-side it will be represented
as a String.
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22.7.5. Collections
22.7.5.1. Bags
Bags cover all collection types including arrays, collections, lists, sets, (but excluding Maps - see
the next section for those), and are implemented client-side as a Javascript array. When calling a
component method that accepts one of these types as a parameter, your parameter should be a
Javascript array. If a component method returns one of these types, then the return value will also
be a Javascript array. The remoting framework is clever enough on the server side to convert the
bag to an appropriate type for the component method call.
22.7.5.2. Maps
As there is no native support for Maps within Javascript, a simple Map implementation is provided
with the Seam Remoting framework. To create a Map which can be used as a parameter to a
remote call, create a new Seam.Remoting.Map object:
var map = new Seam.Remoting.Map();
This Javascript implementation provides basic methods for working with Maps: size(),
isEmpty(), keySet(), values(), get(key), put(key,
value), remove(key) and
contains(key). Each of these methods are equivalent to their Java counterpart. Where the
method returns a collection, such as keySet() and values(), a Javascript Array object will be
returned that contains the key or value objects (respectively).
22.8. Debugging
To aid in tracking down bugs, it is possible to enable a debug mode which will display the contents
of all the packets send back and forth between the client and server in a popup window. To enable
debug mode, either execute the setDebug() method in Javascript:
Seam.Remoting.setDebug(true);
Or configure it via components.xml:
<remoting:remoting debug="true"/>
To turn off debugging, call setDebug(false). If you want to write your own messages to the
debug log, call Seam.Remoting.log(message).
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22.9. The Loading Message
The default loading message that appears in the top right corner of the screen can be modified,
its rendering customised or even turned off completely.
22.9.1. Changing the message
To change the message from the default "Please Wait..." to something different, set the value of
Seam.Remoting.loadingMessage:
Seam.Remoting.loadingMessage = "Loading...";
22.9.2. Hiding the loading message
To completely suppress the display of the loading message, override the implementation of
displayLoadingMessage() and hideLoadingMessage() with functions that instead do nothing:
// don't display the loading indicator
Seam.Remoting.displayLoadingMessage = function() {};
Seam.Remoting.hideLoadingMessage = function() {};
22.9.3. A Custom Loading Indicator
It is also possible to override the loading indicator to display an animated icon, or anything else
that you want. To do this override the displayLoadingMessage() and hideLoadingMessage()
messages with your own implementation:
Seam.Remoting.displayLoadingMessage = function() {
// Write code here to display the indicator
};
Seam.Remoting.hideLoadingMessage = function() {
// Write code here to hide the indicator
};
22.10. Controlling what data is returned
When a remote method is executed, the result is serialized into an XML response that is returned
to the client. This response is then unmarshaled by the client into a Javascript object. For
complex types (i.e. Javabeans) that include references to other objects, all of these referenced
objects are also serialized as part of the response. These objects may reference other objects,
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Constraining normal fields
which may reference other objects, and so forth. If left unchecked, this object "graph" could
potentially be enormous, depending on what relationships exist between your objects. And as
a side issue (besides the potential verbosity of the response), you might also wish to prevent
sensitive information from being exposed to the client.
Seam Remoting provides a simple means to "constrain" the object graph, by specifying the
exclude field of the remote method's @WebRemote annotation. This field accepts a String array
containing one or more paths specified using dot notation. When invoking a remote method, the
objects in the result's object graph that match these paths are excluded from the serialized result
packet.
For all our examples, we'll use the following Widget class:
@Name("widget")
public class Widget
{
private String value;
private String secret;
private Widget child;
private Map<String,Widget> widgetMap;
private List<Widget> widgetList;
// getters and setters for all fields
}
22.10.1. Constraining normal fields
If your remote method returns an instance of Widget, but you don't want to expose the secret
field because it contains sensitive information, you would constrain it like this:
@WebRemote(exclude = {"secret"})
public Widget getWidget();
The value "secret" refers to the secret field of the returned object. Now, suppose that we don't
care about exposing this particular field to the client. Instead, notice that the Widget value that
is returned has a field child that is also a Widget. What if we want to hide the child's secret
value instead? We can do this by using dot notation to specify this field's path within the result's
object graph:
@WebRemote(exclude = {"child.secret"})
public Widget getWidget();
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22.10.2. Constraining Maps and Collections
The other place that objects can exist within an object graph are within a Map or some kind of
collection (List, Set, Array, etc). Collections are easy, and are treated like any other field. For
example, if our Widget contained a list of other Widgets in its widgetList field, to constrain the
secret field of the Widgets in this list the annotation would look like this:
@WebRemote(exclude = {"widgetList.secret"})
public Widget getWidget();
To constrain a Map's key or value, the notation is slightly different. Appending [key] after the Map's
field name will constrain the Map's key object values, while [value] will constrain the value object
values. The following example demonstrates how the values of the widgetMap field have their
secret field constrained:
@WebRemote(exclude = {"widgetMap[value].secret"})
public Widget getWidget();
22.10.3. Constraining objects of a specific type
There is one last notation that can be used to constrain the fields of a type of object no matter
where in the result's object graph it appears. This notation uses either the name of the component
(if the object is a Seam component) or the fully qualified class name (only if the object is not a
Seam component) and is expressed using square brackets:
@WebRemote(exclude = {"[widget].secret"})
public Widget getWidget();
22.10.4. Combining Constraints
Constraints can also be combined, to filter objects from multiple paths within the object graph:
@WebRemote(exclude = {"widgetList.secret", "widgetMap[value].secret"})
public Widget getWidget();
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JMS Messaging
22.11. JMS Messaging
Seam Remoting provides experimental support for JMS Messaging. This section describes the
JMS support that is currently implemented, but please note that this may change in the future. It
is currently not recommended that this feature is used within a production environment.
22.11.1. Configuration
Before you can subscribe to a JMS topic, you must first configure a list
of the topics that can be subscribed to by Seam Remoting. List the topics
under org.jboss.seam.remoting.messaging.subscriptionRegistry.allowedTopics in
seam.properties, web.xml or components.xml.
<remoting:remoting poll-timeout="5" poll-interval="1"/>
22.11.2. Subscribing to a JMS Topic
The following example demonstrates how to subscribe to a JMS Topic:
function subscriptionCallback(message)
{
if (message instanceof Seam.Remoting.TextMessage)
alert("Received message: " + message.getText());
}
Seam.Remoting.subscribe("topicName", subscriptionCallback);
The Seam.Remoting.subscribe() method accepts two parameters, the first being the name of
the JMS Topic to subscribe to, the second being the callback function to invoke when a message
is received.
There are two types of messages supported, Text messages and Object messages. If you
need to test for the type of message that is passed to your callback function you can use
the instanceof operator to test whether the message is a Seam.Remoting.TextMessage or
Seam.Remoting.ObjectMessage. A TextMessage contains the text value in its text field (or
alternatively call getText() on it), while an ObjectMessage contains its object value in its value
field (or call its getValue() method).
22.11.3. Unsubscribing from a Topic
To unsubscribe from a topic, call Seam.Remoting.unsubscribe() and pass in the topic name:
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Seam.Remoting.unsubscribe("topicName");
22.11.4. Tuning the Polling Process
There are two parameters which you can modify to control how polling occurs. The first one is
Seam.Remoting.pollInterval, which controls how long to wait between subsequent polls for
new messages. This parameter is expressed in seconds, and its default setting is 10.
The second parameter is Seam.Remoting.pollTimeout, and is also expressed as seconds. It
controls how long a request to the server should wait for a new message before timing out and
sending an empty response. Its default is 0 seconds, which means that when the server is polled,
if there are no messages ready for delivery then an empty response will be immediately returned.
Caution should be used when setting a high pollTimeout value; each request that has to wait for
a message means that a server thread is tied up until a message is received, or until the request
times out. If many such requests are being served simultaneously, it could mean a large number
of threads become tied up because of this reason.
It is recommended that you set these options via components.xml, however they can be overridden
via Javascript if desired. The following example demonstrates how to configure the polling to occur
much more aggressively. You should set these parameters to suitable values for your application:
Via components.xml:
<remoting:remoting poll-timeout="5" poll-interval="1"/>
Via JavaScript:
// Only wait 1 second between receiving a poll response and sending the next poll request.
Seam.Remoting.pollInterval = 1;
// Wait up to 5 seconds on the server for new messages
Seam.Remoting.pollTimeout = 5;
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Chapter 23.
Seam and the Google Web Toolkit
For those that prefer to use the Google Web Toolkit (GWT) to develop dynamic AJAX applications,
Seam provides an integration layer that allows GWT widgets to interact directly with Seam
components.
To use GWT, we assume that you are already familiar with the GWT tools - more information
can be found at http://code.google.com/webtoolkit/. This chapter does not attempt to explain how
GWT works or how to use it.
23.1. Configuration
There is no special configuration required to use GWT in a Seam application, however the Seam
resource servlet must be installed. See Chapter 26, Configuring Seam and packaging Seam
applications for details.
23.2. Preparing your component
The first step in preparing a Seam component to be called via GWT, is to create both synchronous
and asynchronous service interfaces for the methods you wish to call. Both of these interfaces
should extend the GWT interface com.google.gwt.user.client.rpc.RemoteService:
public interface MyService extends RemoteService {
public String askIt(String question);
}
The asynchronous interface should be identical, except that it also contains an additional
AsyncCallback parameter for each of the methods it declares:
public interface MyServiceAsync extends RemoteService {
public void askIt(String question, AsyncCallback callback);
}
The asynchronous interface, in this example MyServiceAsync, will be implemented by GWT and
should never be implemented directly.
The next step, is to create a Seam component that implements the synchronous interface:
@Name("org.jboss.seam.example.remoting.gwt.client.MyService")
public class ServiceImpl implements MyService {
@WebRemote
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public String askIt(String question) {
if (!validate(question)) {
throw new IllegalStateException("Hey, this shouldn't happen, I checked on the client, " +
"but its always good to double check.");
}
return "42. Its the real question that you seek now.";
}
public boolean validate(String q) {
ValidationUtility util = new ValidationUtility();
return util.isValid(q);
}
}
The methods that should be made accessible via GWT need to be annotated with the @WebRemote
annotation, which is required for all web-remoteable methods.
23.3. Hooking up a GWT widget to the Seam component
The next step, is to write a method that returns the asynchronous interface to the component.
This method can be located inside the widget class, and will be used by the widget to obtain a
reference to the asynchronous client stub:
private MyServiceAsync getService() {
String endpointURL = GWT.getModuleBaseURL() + "seam/resource/gwt";
MyServiceAsync svc = (MyServiceAsync) GWT.create(MyService.class);
((ServiceDefTarget) svc).setServiceEntryPoint(endpointURL);
return svc;
}
The final step is to write the widget code that invokes the method on the client stub. The following
example creates a simple user interface with a label, text input and a button:
public class AskQuestionWidget extends Composite {
private AbsolutePanel panel = new AbsolutePanel();
public AskQuestionWidget() {
Label lbl = new Label("OK, what do you want to know?");
panel.add(lbl);
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Hooking up a GWT widget to the Seam
component
final TextBox box = new TextBox();
box.setText("What is the meaning of life?");
panel.add(box);
Button ok = new Button("Ask");
ok.addClickListener(new ClickListener() {
public void onClick(Widget w) {
ValidationUtility valid = new ValidationUtility();
if (!valid.isValid(box.getText())) {
Window.alert("A question has to end with a '?'");
} else {
askServer(box.getText());
}
}
});
panel.add(ok);
initWidget(panel);
}
private void askServer(String text) {
getService().askIt(text, new AsyncCallback() {
public void onFailure(Throwable t) {
Window.alert(t.getMessage());
}
public void onSuccess(Object data) {
Window.alert((String) data);
}
});
}
...
When clicked, the button invokes the askServer() method passing the contents of the input
text (in this example, validation is also performed to ensure that the input is a valid question).
The askServer() method acquires a reference to the asynchronous client stub (returned by the
getService() method) and invokes the askIt() method. The result (or error message if the call
fails) is shown in an alert window.
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The complete code for this example can be found in the Seam distribution in the examples/
remoting/gwt directory.
23.4. GWT Ant Targets
For deployment of GWT apps, there is a compile-to-Javascript step (which compacts and
obfuscates the code). There is an ant utility which can be used instead of the command line or GUI
utility that GWT provides. To use this, you will need to have the ant task jar in your ant classpath,
as well as GWT downloaded (which you will need for hosted mode anyway).
Then, in your ant file, place (near the top of your ant file):
<taskdef uri="antlib:de.samaflost.gwttasks"
resource="de/samaflost/gwttasks/antlib.xml"
classpath="./lib/gwttasks.jar"/>
<property file="build.properties"/>
Create a build.properties file, which has the contents:
gwt.home=/gwt_home_dir
This of course should point to the directory where GWT is installed. Then to use it, create a target:
<!-- the following are are handy utilities for doing GWT development.
To use GWT, you will of course need to download GWT seperately -->
<target name="gwt-compile">
<!-- in this case, we are "re homing" the gwt generated stuff, so in this case
we can only have one GWT module - we are doing this deliberately to keep the URL short -->
<delete>
<fileset dir="view"/>
</delete>
<gwt:compile outDir="build/gwt"
gwtHome="${gwt.home}"
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GWT Ant Targets
classBase="${gwt.module.name}"
sourceclasspath="src"/>
<copy todir="view">
<fileset dir="build/gwt/${gwt.module.name}"/>
</copy>
</target>
This target when called will compile the GWT application, and copy it to the specified directory
(which would be in the webapp part of your war - remember GWT generates HTML and Javascript
artifacts). You never edit the resulting code that gwt-compile generates - you always edit in the
GWT source directory.
Remember that GWT comes with a hosted mode browser - you should be using that if you are
developing with GWT. If you aren't using that, and are just compiling it each time, you aren't getting
the most out of the toolkit (in fact, if you can't or won't use the hosted mode browser, I would go
far as to say you should NOT be using GWT at all - it's that valuable!).
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Chapter 24.
Spring Framework integration
The Spring integration module allows easy migration of Spring-based projects to Seam and allows
Spring applications to take advantage of key Seam features like conversations and Seam's more
sophisticated persistence context management.
Note! The Spring integration code is included in the jboss-seam-ioc library. This dependency is
required for all seam-spring integration techniques covered in this chapter.
Seam's support for Spring provides the ability to:
• inject Seam component instances into Spring beans
• inject Spring beans into Seam components
• turn Spring beans into Seam components
• allow Spring beans to live in any Seam context
• start a spring WebApplicationContext with a Seam component
• Support for Spring PlatformTransactionManagement
• provides a Seam managed replacement for Spring's OpenEntityManagerInViewFilter and
OpenSessionInViewFilter
• Support for Spring TaskExecutors to back @Asynchronous calls
24.1. Injecting Seam components into Spring beans
Injecting Seam component instances into Spring beans is accomplished using the
<seam:instance/> namespace handler. To enable the Seam namespace handler, the Seam
namespace must be added to the Spring beans definition file:
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:seam="http://jboss.com/products/seam/spring-seam"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-2.0.xsd
http://jboss.com/products/seam/spring-seam
http://jboss.com/products/seam/spring-seam-2.1.xsd">
Now any Seam component may be injected into any Spring bean:
<bean id="someSpringBean" class="SomeSpringBeanClass" scope="prototype">
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Chapter 24. Spring Framework ...
<property name="someProperty">
<seam:instance name="someComponent"/>
</property>
</bean>
An EL expression may be used instead of a component name:
<bean id="someSpringBean" class="SomeSpringBeanClass" scope="prototype">
<property name="someProperty">
<seam:instance name="#{someExpression}"/>
</property>
</bean>
Seam component instances may even be made available for injection into Spring beans by a
Spring bean id.
<seam:instance name="someComponent" id="someSeamComponentInstance"/>
<bean id="someSpringBean" class="SomeSpringBeanClass" scope="prototype">
<property name="someProperty" ref="someSeamComponentInstance">
</bean>
Now for the caveat!
Seam was designed from the ground up to support a stateful component model with multiple
contexts. Spring was not. Unlike Seam bijection, Spring injection does not occur at method
invocation time. Instead, injection happens only when the Spring bean is instantiated. So the
instance available when the bean is instantiated will be the same instance that the bean uses for
the entire life of the bean. For example, if a Seam CONVERSATION-scoped component instance
is directly injected into a singleton Spring bean, that singleton will hold a reference to the same
instance long after the conversation is over! We call this problem scope impedance. Seam bijection
ensures that scope impedance is maintained naturally as an invocation flows through the system.
In Spring, we need to inject a proxy of the Seam component, and resolve the reference when
the proxy is invoked.
The <seam:instance/> tag lets us automatically proxy the Seam component.
<seam:instance id="seamManagedEM" name="someManagedEMComponent" proxy="true"/>
<bean id="someSpringBean" class="SomeSpringBeanClass">
<property name="entityManager" ref="seamManagedEM">
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Injecting Spring beans into Seam components
</bean>
This example shows one way to use a Seam-managed persistence context from a Spring bean.
(For a more robust way to use Seam-managed persistence contexts as a replacement for the
Spring OpenEntityManagerInView filter see section on Using a Seam Managed Persistence
Context in Spring)
24.2. Injecting Spring beans into Seam components
It is even easier to inject Spring beans into Seam component instances. Actually, there are two
possible approaches:
• inject a Spring bean using an EL expression
• make the Spring bean a Seam component
We'll discuss the second option in the next section. The easiest approach is to access the Spring
beans via EL.
The Spring DelegatingVariableResolver is an integration point Spring provides for integrating
Spring with JSF. This VariableResolver makes all Spring beans available in EL by their bean
id. You'll need to add the DelegatingVariableResolver to faces-config.xml:
<application>
<variable-resolver>
org.springframework.web.jsf.DelegatingVariableResolver
</variable-resolver>
</application>
Then you can inject Spring beans using @In:
@In("#{bookingService}")
private BookingService bookingService;
The use of Spring beans in EL is not limited to injection. Spring beans may be used anywhere that
EL expressions are used in Seam: process and pageflow definitions, working memory assertions,
etc...
24.3. Making a Spring bean into a Seam component
The <seam:component/> namespace handler can be used to make any Spring bean a Seam
component. Just place the <seam:component/> tag within the declaration of the bean that you
wish to be a Seam component:
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Chapter 24. Spring Framework ...
<bean id="someSpringBean" class="SomeSpringBeanClass" scope="prototype">
<seam:component/>
</bean>
By default, <seam:component/> will create a STATELESS Seam component with class and name
provided in the bean definition. Occasionally, such as when a FactoryBean is used, the class of
the Spring bean may not be the class appearing in the bean definition. In such cases the class
should be explicitly specified. A Seam component name may be explicitly specified in cases where
there is potential for a naming conflict.
The scope attribute of <seam:component/> may be used if you wish the Spring bean to be
managed in a particular Seam scope. The Spring bean must be scoped to prototype if the
Seam scope specified is anything other than STATELESS. Pre-existing Spring beans usually have
a fundamentally stateless character, so this attribute is not usually needed.
24.4. Seam-scoped Spring beans
The Seam integration package also lets you use Seam's contexts as Spring 2.0 style custom
scopes. This lets you declare any Spring bean in any of Seam's contexts. However, note once
again that Spring's component model was never architected to support statefulness, so please
use this feature with great care. In particular, clustering of session or conversation scoped Spring
beans is deeply problematic, and care must be taken when injecting a bean or component from
a wider scope into a bean of a narrower scope.
By specifying <seam:configure-scopes/> once in a Spring bean factory configuration, all of the
Seam scopes will be available to Spring beans as custom scopes. To associate a Spring bean
with a particular Seam scope, specify the Seam scope in the scope attribute of the bean definition.
<!-- Only needs to be specified once per bean factory-->
<seam:configure-scopes/>
...
<bean
id="someSpringBean"
scope="seam.CONVERSATION"/>
class="SomeSpringBeanClass"
The prefix of the scope name may be changed by specifying the prefix attribute in the
configure-scopes definition. (The default prefix is seam.)
By default an instance of a Spring Component registered in this way is not automatically
created when referenced using @In. To have an instance auto-created you must either specify
@In(create=true) at the injection point to identify a specific bean to be auto created or you can
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Using Spring PlatformTransactionManagement
use the default-auto-create attribute of configure-scopes to make all spring beans who use
a seam scope auto created.
Seam-scoped Spring beans defined this way can be injected into other Spring beans without
the use of <seam:instance/>. However, care must be taken to ensure scope impedance is
maintained. The normal approach used in Spring is to specify <aop:scoped-proxy/> in the bean
definition. However, Seam-scoped Spring beans are not compatible with <aop:scoped-proxy/>.
So if you need to inject a Seam-scoped Spring bean into a singleton, <seam:instance/> must
be used:
<bean
id="someSpringBean"
scope="seam.CONVERSATION"/>
class="SomeSpringBeanClass"
...
<bean id="someSingleton">
<property name="someSeamScopedSpringBean">
<seam:instance name="someSpringBean" proxy="true"/>
</property>
</bean>
24.5. Using Spring PlatformTransactionManagement
Spring provides an extensible transaction management abstraction with support for many
transaction APIs (JPA, Hibernate, JDO, and JTA) Spring also provides tight integrations
with many application server TransactionManagers such as Websphere and Weblogic. Spring
transaction management exposes support for many advanced features such as nested
transactions and supports full Java EE transaction propagation rules like REQUIRES_NEW
and NOT_SUPPORTED. For more information see the spring documentation here [http://
static.springframework.org/spring/docs/2.0.x/reference/transaction.html].
To configure Seam to use Spring transactions enable the SpringTransaction component like so:
<spring:spring-transaction platform-transaction-manager="#{transactionManager}"/>
The spring:spring-transaction component will utilize Springs transaction synchronization
capabilities for synchronization callbacks.
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Chapter 24. Spring Framework ...
24.6. Using a Seam Managed Persistence Context in
Spring
One of the most powerful features of Seam is its conversation scope and the ability
to have an EntityManager open for the life of a conversation. This eliminates many of
the problems associated with the detachment and re-attachment of entities as well as
mitigates occurrences of the dreaded LazyInitializationException. Spring does not provide
a way to manage an persistence context beyond the scope of a single web request
(OpenEntityManagerInViewFilter). So, it would be nice if Spring developers could have access
to a Seam managed persistence context using all of the same tools Spring provides for integration
with JPA(e.g. PersistenceAnnotationBeanPostProcessor, JpaTemplate, etc.)
Seam provides a way for Spring to access a Seam managed persistence context with Spring's
provided JPA tools bringing conversation scoped persistence context capabilities to Spring
applications.
This integration work provides the following functionality:
• transparent access to a Seam managed persistence context using Spring provided tools
• access to Seam conversation scoped persistence contexts in a non web request (e.g.
asynchronous quartz job)
• allows for using Seam managed persistence contexts with Spring managed transactions (will
need to flush the persistence context manually)
Spring's persistence context propagation model allows only one open EntityManager per
EntityManagerFactory so the Seam integration works by wrapping an EntityManagerFactory
around a Seam managed persistence context.
<bean
id="seamEntityManagerFactory"
class="org.jboss.seam.ioc.spring.SeamManagedEntityManagerFactoryBean">
<property name="persistenceContextName" value="entityManager"/>
</bean>
Where 'persistenceContextName' is the name of the Seam managed persistence context
component. By default this EntityManagerFactory has a unitName equal to the Seam component
name or in this case 'entityManager'. If you wish to provide a different unitName you can do so
by providing a persistenceUnitName like so:
<bean
id="seamEntityManagerFactory"
class="org.jboss.seam.ioc.spring.SeamManagedEntityManagerFactoryBean">
<property name="persistenceContextName" value="entityManager"/>
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Using a Seam Managed Persistence Context in
Spring
<property name="persistenceUnitName" value="bookingDatabase:extended"/>
</bean>
This EntityManagerFactory can then be used in any Spring provided tools. For example, using
Spring's PersistenceAnnotationBeanPostProcessor is the exact same as before.
<bean
class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor"/>
If you define your real EntityManagerFactory in Spring but wish to use a Seam managed
persistence context you can tell the PersistenceAnnotationBeanPostProcessor which
persistenctUnitName you wish to use by default by specifying the defaultPersistenceUnitName
property.
The applicationContext.xml might look like:
<bean
id="entityManagerFactory"
class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean">
<property name="persistenceUnitName" value="bookingDatabase"/>
</bean>
<bean
id="seamEntityManagerFactory"
class="org.jboss.seam.ioc.spring.SeamManagedEntityManagerFactoryBean">
<property name="persistenceContextName" value="entityManager"/>
<property name="persistenceUnitName" value="bookingDatabase:extended"/>
</bean>
<bean
class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor">
<property name="defaultPersistenceUnitName" value="bookingDatabase:extended"/>
</bean>
The component.xml might look like:
<persistence:managed-persistence-context name="entityManager"
auto-create="true" entity-manager-factory="#{entityManagerFactory}"/>
JpaTemplate and JpaDaoSupport are configured the same way for a Seam managed persistence
context as they would be fore a Seam managed persistence context.
<bean id="bookingService" class="org.jboss.seam.example.spring.BookingService">
<property name="entityManagerFactory" ref="seamEntityManagerFactory"/>
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Chapter 24. Spring Framework ...
</bean>
24.7. Using a Seam Managed Hibernate Session in
Spring
The Seam Spring integration also provides support for complete access to a Seam managed
Hibernate session using spring's tools. This integration is very similar to the JPA integration.
Like Spring's JPA integration spring's propagation model allows only one open EntityManager per
EntityManagerFactory per transaction??? to be available to spring tools. So, the Seam Session
integration works by wrapping a proxy SessionFactory around a Seam managed Hibernate
session context.
<bean
id="seamSessionFactory"
class="org.jboss.seam.ioc.spring.SeamManagedSessionFactoryBean">
<property name="sessionName" value="hibernateSession"/>
</bean>
Where 'sessionName' is the name of the persistence:managed-hibernate-session
component. This SessionFactory can then be used in any Spring provided tools. The integration
also provides support for calls to SessionFactory.getCurrentInstance() as long as you call
getCurrentInstance() on the SeamManagedSessionFactory.
24.8. Spring Application Context as a Seam Component
Although it is possible to use the Spring ContextLoaderListener to start your application's Spring
ApplicationContext there are a couple of limitations.
• the Spring ApplicationContext must be started after the SeamListener
• it can be tricky starting a Spring ApplicationContext for use in Seam unit and integration tests
To overcome these two limitations the Spring integration includes a Seam component that will
start a Spring ApplicationContext. To use this Seam component place the <spring:contextloader/> definition in the components.xml. Specify your Spring context file location in the
config-locations attribute. If more than one config file is needed you can place them in the
nested <spring:config-locations/> element following standard components.xml multi value
practices.
<components xmlns="http://jboss.com/products/seam/components"
xmlns:spring="http://jboss.com/products/seam/spring"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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Using a Spring TaskExecutor for
@Asynchronous
xsi:schemaLocation="http://jboss.com/products/seam/components
http://jboss.com/products/seam/components-2.1.xsd
http://jboss.com/products/seam/spring
http://jboss.com/products/seam/spring-2.1.xsd">
<spring:context-loader config-locations="/WEB-INF/applicationContext.xml"/>
</components>
24.9. Using a Spring TaskExecutor for @Asynchronous
Spring provides an abstraction for executing code asynchronously called a TaskExecutor.
The Spring Seam integration allows for the use of a Spring TaskExecutor for
executing immediate @Asynchronous method calls. To enable this functionality install the
SpringTaskExecutorDispatchor and provide a spring bean defined taskExecutor like so:
<spring:task-executor-dispatcher task-executor="#{springThreadPoolTaskExecutor}"/>
Because a Spring TaskExecutor does not support scheduling of an asynchronous event a fallback
Seam Dispatcher can be provided to handle scheduled asynchronous event like so:
<!-- Install a ThreadPoolDispatcher to handle scheduled asynchronous event -->
<core:thread-pool-dispatcher name="threadPoolDispatcher"/>
<!-- Install the SpringDispatcher as default -->
<spring:task-executor-dispatcher
task-executor="#{springThreadPoolTaskExecutor}"
schedule-dispatcher="#{threadPoolDispatcher}"/>
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Chapter 25.
Hibernate Search
25.1. Introduction
Full text search engines like Apache Lucene™ are a very powerful technology that bring full text
and efficient queries to applications. Hibernate Search, which uses Apache Lucene under the
covers, indexes your domain model with the addition of a few annotations, takes care of the
database / index synchronization and returns regular managed objects that are matched by full
text queries. Keep in mind, thought, that there are mismatches that arise when dealing with an
object domain model over a text index (keeping the index up to date, mismatch between the index
structure and the domain model, and querying mismatch). But the benefits of speed and efficiency
far outweigh these limitations.
Hibernate Search has been designed to integrates nicely and as naturally as possible with JPA
and Hibernate. As a natural extension, JBoss Seam provides an Hibernate Search integration.
Please refer to the Hibernate Search documentation [http://www.hibernate.org/hib_docs/search/
reference/en/html_single/] for information specific to the Hibernate Search project.
25.2. Configuration
Hibernate Search is configured either in the META-INF/persistence.xml or hibernate.cfg.xml
file.
Hibernate Search configuration has sensible defaults for most configuration parameters. Here is
a minimal persistence unit configuration to get started.
<persistence-unit name="sample">
<jta-data-source>java:/DefaultDS</jta-data-source>
<properties>
[...]
<!-- use a file system based index -->
<property name="hibernate.search.default.directory_provider"
value="org.hibernate.search.store.FSDirectoryProvider"/>
<!-- directory where the indexes will be stored -->
<property name="hibernate.search.default.indexBase"
value="/Users/prod/apps/dvdstore/dvdindexes"/>
</properties>
</persistence-unit>
If you plan to target Hibernate Annotations or EntityManager 3.2.x (embedded into JBoss AS
4.2.GA), you also need to configure the appropriate event listeners.
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Chapter 25. Hibernate Search
<persistence-unit name="sample">
<jta-data-source>java:/DefaultDS</jta-data-source>
<properties>
[...]
<!-- use a file system based index -->
<property name="hibernate.search.default.directory_provider"
value="org.hibernate.search.store.FSDirectoryProvider"/>
<!-- directory where the indexes will be stored -->
<property name="hibernate.search.default.indexBase"
value="/Users/prod/apps/dvdstore/dvdindexes"/>
<property name="hibernate.ejb.event.post-insert"
value="org.hibernate.search.event.FullTextIndexEventListener"/>
<property name="hibernate.ejb.event.post-update"
value="org.hibernate.search.event.FullTextIndexEventListener"/>
<property name="hibernate.ejb.event.post-delete"
value="org.hibernate.search.event.FullTextIndexEventListener"/>
</properties>
</persistence-unit>
Note
This step is no longer necessary if Hibernate Annotation or EntityManager 3.3.x
are used.
In addition to the configuration file, the following jars have to be deployed:
• hibernate-search.jar
• hibernate-commons-annotations.jar
• lucene-core.jar
Note
If you deploy those in a EAR, don't forget to update application.xml
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Usage
25.3. Usage
Hibernate Search uses annotations to map entities to a Lucene index, check the reference
documentation [http://www.hibernate.org/hib_docs/search/reference/en/html_single/] for more
informations.
Hibernate Search is fully integrated with the API and semantic of JPA / Hibernate. Switching from
a HQL or Criteria based query requires just a few lines of code. The main API the application
interacts with is the FullTextSession API (subclass of Hibernate's Session).
When Hibernate Search is present, JBoss Seam injects a FullTextSession.
@Stateful
@Name("search")
public class FullTextSearchAction implements FullTextSearch, Serializable {
@In FullTextSession session;
public void search(String searchString) {
org.apache.lucene.query.Query luceneQuery = getLuceneQuery();
org.hibernate.Query query session.createFullTextQuery(luceneQuery, Product.class);
searchResults = query
.setMaxResults(pageSize + 1)
.setFirstResult(pageSize * currentPage)
.list();
}
[...]
}
Note
FullTextSession extends org.hibernate.Session so that it can be used as a
regular Hibernate Session
If the Java Persistence API is used, a smoother integration is proposed.
@Stateful
@Name("search")
public class FullTextSearchAction implements FullTextSearch, Serializable {
@In FullTextEntityManager em;
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Chapter 25. Hibernate Search
public void search(String searchString) {
org.apache.lucene.query.Query luceneQuery = getLuceneQuery();
javax.persistence.Query query = em.createFullTextQuery(luceneQuery, Product.class);
searchResults = query
.setMaxResults(pageSize + 1)
.setFirstResult(pageSize * currentPage)
.getResultList();
}
[...]
}
When
Hibernate
Search is present, a FulltextEntityManager is injected.
FullTextEntityManager extends EntityManager with search specific methods, the same way
FullTextSession extends Session.
When an EJB 3.0 Session or Message Driven Bean injection is used (i.e. via the
@PersistenceContext annotation), it is not possible to replace the EntityManager interface by
the FullTextEntityManager interface in the declaration statement. However, the implementation
injected will be a FullTextEntityManager implementation: downcasting is then possible.
@Stateful
@Name("search")
public class FullTextSearchAction implements FullTextSearch, Serializable {
@PersistenceContext EntityManager em;
public void search(String searchString) {
org.apache.lucene.query.Query luceneQuery = getLuceneQuery();
FullTextEntityManager ftEm = (FullTextEntityManager) em;
javax.persistence.Query query = ftEm.createFullTextQuery(luceneQuery, Product.class);
searchResults = query
.setMaxResults(pageSize + 1)
.setFirstResult(pageSize * currentPage)
.getResultList();
}
[...]
}
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Usage
Caution
For people accustomed to Hibernate Search out of Seam, note that using
Search.createFullTextSession is not necessary.
Check the DVDStore or the blog examples of the JBoss Seam distribution for a concrete use of
Hibernate Search.
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352
Chapter 26.
Configuring Seam and packaging
Seam applications
Configuration is a very boring topic and an extremely tedious pastime. Unfortunately, several
lines of XML are required to integrate Seam into your JSF implementation and servlet container.
There's no need to be too put off by the following sections; you'll never need to type any of this
stuff yourself, since you can just copy and paste from the example applications!
26.1. Basic Seam configuration
First, let's look at the basic configuration that is needed whenever we use Seam with JSF.
26.1.1. Integrating Seam with JSF and your servlet container
Of course, you need a faces servlet!
<servlet>
<servlet-name>Faces Servlet</servlet-name>
<servlet-class>javax.faces.webapp.FacesServlet</servlet-class>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>Faces Servlet</servlet-name>
<url-pattern>*.seam</url-pattern>
</servlet-mapping>
(You can adjust the URL pattern to suit your taste.)
In addition, Seam requires the following entry in your web.xml file:
<listener>
<listener-class>org.jboss.seam.servlet.SeamListener</listener-class>
</listener>
This listener is responsible for bootstrapping Seam, and for destroying session and application
contexts.
Some JSF implementations have a broken implementation of server-side state saving that
interferes with Seam's conversation propagation. If you have problems with conversation
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Chapter 26. Configuring Seam ...
propagation during form submissions, try switching to client-side state saving. You'll need this in
web.xml:
<context-param>
<param-name>javax.faces.STATE_SAVING_METHOD</param-name>
<param-value>client</param-value>
</context-param>
26.1.2. Using facelets
If you want follow our advice and use facelets instead of JSP, add the following lines to facesconfig.xml:
<application>
<view-handler>com.sun.facelets.FaceletViewHandler</view-handler>
</application>
And the following lines to web.xml:
<context-param>
<param-name>javax.faces.DEFAULT_SUFFIX</param-name>
<param-value>.xhtml</param-value>
</context-param>
26.1.3. Seam Resource Servlet
The Seam Resource Servlet provides resources used by Seam Remoting, captchas (see the
security chapter) and some JSF UI controls. Configuring the Seam Resource Servlet requires the
following entry in web.xml:
<servlet>
<servlet-name>Seam Resource Servlet</servlet-name>
<servlet-class>org.jboss.seam.servlet.SeamResourceServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>Seam Resource Servlet</servlet-name>
<url-pattern>/seam/resource/*</url-pattern>
</servlet-mapping>
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26.1.4. Seam servlet filters
Seam doesn't need any servlet filters for basic operation. However, there are several features
which depend upon the use of filters. To make things easier, Seam lets you add and configure
servlet filters just like you would configure other built-in Seam components. To take advantage of
this feature, we must first install a master filter in web.xml:
<filter>
<filter-name>Seam Filter</filter-name>
<filter-class>org.jboss.seam.servlet.SeamFilter</filter-class>
</filter>
<filter-mapping>
<filter-name>Seam Filter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
The Seam master filter must be the first filter specified in web.xml. This ensures it is run first.
The Seam filters share a number of common attributes, you can set these in components.xml in
addition to any parameters discussed below:
• url-pattern — Used to specify which requests are filtered, the default is all requests. urlpattern is a Tomcat style pattern which allows a wildcard suffix.
• regex-url-pattern — Used to specify which requests are filtered, the default is all requests.
regex-url-pattern is a true regular expression match for request path. It's worth noting when
composing the regular expression that the request path does not contain the server or request
context path.
• disabled — Used to disable a built in filter.
Adding the master filter enables the following built-in filters.
26.1.4.1. Exception handling
This filter provides the exception mapping functionality in pages.xml (almost all applications will
need this). It also takes care of rolling back uncommitted transactions when uncaught exceptions
occur. (According to the Java EE specification, the web container should do this automatically, but
we've found that this behavior cannot be relied upon in all application servers. And it is certainly
not required of plain servlet engines like Tomcat.)
By default, the exception handling filter will process all requests, however this behavior may
be adjusted by adding a <web:exception-filter> entry to components.xml, as shown in this
example:
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<components xmlns="http://jboss.com/products/seam/components"
xmlns:web="http://jboss.com/products/seam/web">
<web:exception-filter url-pattern="*.seam"/>
</components>
26.1.4.2. Conversation propagation with redirects
This filter allows Seam to propagate the conversation context across browser redirects. It
intercepts any browser redirects and adds a request parameter that specifies the Seam
conversation identifier.
The redirect filter will process all requests by default, but this behavior can also be adjusted in
components.xml:
<web:redirect-filter url-pattern="*.seam"/>
26.1.4.3. Multipart form submissions
This feature is necessary when using the Seam file upload JSF control. It detects multipart form
requests and processes them according to the multipart/form-data specification (RFC-2388). To
override the default settings, add the following entry to components.xml:
<web:multipart-filter create-temp-files="true"
max-request-size="1000000"
url-pattern="*.seam"/>
• create-temp-files — If set to true, uploaded files are written to a temporary file (instead of
held in memory). This may be an important consideration if large file uploads are expected. The
default setting is false.
• max-request-size — If the size of a file upload request (determined by reading the ContentLength header in the request) exceeds this value, the request will be aborted. The default
setting is 0 (no size limit).
26.1.4.4. Character encoding
Sets the character encoding of submitted form data.
This filter is not installed by default and requires an entry in components.xml to enable it:
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<web:character-encoding-filter encoding="UTF-16"
override-client="true"
url-pattern="*.seam"/>
• encoding — The encoding to use.
• override-client — If this is set to true, the request encoding will be set to whatever is
specified by encoding no matter whether the request already specifies an encoding or not. If
set to false, the request encoding will only be set if the request doesn't already specify an
encoding. The default setting is false.
26.1.4.5. RichFaces
If RichFaces is used in your project, Seam will install the RichFaces Ajax filter for you, making
sure to install it before all other built-in filters. You don't need to install the RichFaces Ajax filter
in web.xml yourself.
The RichFaces Ajax filter is only installed if the RichFaces jars are present in your project.
To override the default settings, add the following entry to components.xml. The options are the
same as those specified in the RichFaces Developer Guide:
<web:ajax4jsf-filter force-parser="true"
enable-cache="true"
log4j-init-file="custom-log4j.xml"
url-pattern="*.seam"/>
• force-parser — forces all JSF pages to be validated by Richfaces's XML syntax checker. If
false, only AJAX responses are validated and converted to well-formed XML. Setting forceparser to false improves performance, but can provide visual artifacts on AJAX updates.
• enable-cache — enables caching of framework-generated resources (e.g. javascript, CSS,
images, etc). When developing custom javascript or CSS, setting to true prevents the browser
from caching the resource.
• log4j-init-file — is used to setup per-application logging. A path, relative to web application
context, to the log4j.xml configuration file should be provided.
26.1.4.6. Identity Logging
This filter adds the authenticated user name to the log4j mapped diagnostic context so that it can
be included in formatted log output if desired, by adding %X{username} to the pattern.
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By default, the logging filter will process all requests, however this behavior may be adjusted by
adding a <web:logging-filter> entry to components.xml, as shown in this example:
<components xmlns="http://jboss.com/products/seam/components"
xmlns:web="http://jboss.com/products/seam/web">
<web:logging-filter url-pattern="*.seam"/>
</components>
26.1.4.7. Context management for custom servlets
Requests sent direct to some servlet other than the JSF servlet are not processed through the
JSF lifecycle, so Seam provides a servlet filter that can be applied to any other servlet that needs
access to Seam components.
This filter allows custom servlets to interact with the Seam contexts. It sets up the Seam contexts
at the beginning of each request, and tears them down at the end of the request. You should make
sure that this filter is never applied to the JSF FacesServlet. Seam uses the phase listener for
context management in a JSF request.
This filter is not installed by default and requires an entry in components.xml to enable it:
<web:context-filter url-pattern="/media/*"/>
The context filter expects to find the conversation id of any conversation context in a request
parameter named conversationId. You are responsible for ensuring that it gets sent in the
request.
You are also responsible for ensuring propagation of any new conversation id back to the client.
Seam exposes the conversation id as a property of the built in component conversation.
26.1.4.8. Adding custom filters
Seam can install your filters for you, allowing you to specify where in the chain your filter is
placed (the servlet specification doesn't provide a well defined order if you specify your filters in
a web.xml). Just add the @Filter annotation to your Seam component (which must implement
javax.servlet.Filter):
@Startup
@Scope(APPLICATION)
@Name("org.jboss.seam.web.multipartFilter")
@BypassInterceptors
@Filter(within="org.jboss.seam.web.ajax4jsfFilter")
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public class MultipartFilter extends AbstractFilter {
Adding the @Startup annotation means thar the component is available during Seam startup;
bijection isn't available here (@BypassInterceptors); and the filter should be further down the
chain than the RichFaces filter (@Filter(within="org.jboss.seam.web.ajax4jsfFilter")).
26.1.5. Integrating Seam with your EJB container
We need to apply the SeamInterceptor to our Seam components. The simplest way to do this
across an entire application is to add the following interceptor configuration in ejb-jar.xml:
<interceptors>
<interceptor>
<interceptor-class>org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
</interceptor>
</interceptors>
<assembly-descriptor>
<interceptor-binding>
<ejb-name>*</ejb-name>
<interceptor-class>org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
</interceptor-binding>
</assembly-descriptor>
Seam needs to know where to go to find session beans in JNDI. One way to do this is specify
the @JndiName annotation on every session bean Seam component. However, this is quite
tedious. A better approach is to specify a pattern that Seam can use to calculate the JNDI
name from the EJB name. Unfortunately, there is no standard mapping to global JNDI defined
in the EJB3 specification, so this mapping is vendor-specific. We usually specify this option in
components.xml.
For JBoss AS, the following pattern is correct:
<core:init jndi-name="myEarName/#{ejbName}/local" />
Where myEarName is the name of the EAR in which the bean is deployed.
Outside the context of an EAR (when using the JBoss Embeddable EJB3 container), the following
pattern is the one to use:
<core:init jndi-name="#{ejbName}/local" />
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You'll have to experiment to find the right setting for other application servers. Note that some
servers (such as GlassFish) require you to specify JNDI names for all EJB components explicitly
(and tediously). In this case, you can pick your own pattern ;-)
In an EJB3 environment, we recommend the use of a special built-in component for transaction
management, that is fully aware of container transactions, and can correctly process transaction
success events registered with the Events component. If you don't add this line to your
components.xml file, Seam won't know when container-managed transactions end:
<transaction:ejb-transaction/>
26.1.6. Don't forget!
There is one final item you need to know about. You must place a seam.properties, METAINF/seam.properties or META-INF/components.xml file in any archive in which your Seam
components are deployed (even an empty properties file will do). At startup, Seam will scan any
archives with seam.properties files for seam components.
In a web archive (WAR) file, you must place a seam.properties file in the WEB-INF/classes
directory if you have any Seam components included here.
That's why all the Seam examples have an empty seam.properties file. You can't just delete
this file and expect everything to still work!
You might think this is silly and what kind of idiot framework designers would make an empty file
affect the behavior of their software?? Well, this is a workaround for a limitation of the JVM—if
we didn't use this mechanism, our next best option would be to force you to list every component
explicitly in components.xml, just like some other competing frameworks do! I think you'll like our
way better.
26.2. Using Alternate JPA Providers
Seam comes packaged and configured with Hibernate as the default JPA provider. If you require
using a different JPA provider you must tell seam about it.
This is a workaround
Configuration of the JPA provider will be easier in the future and will not require
configuration changes, unless you are adding a custom persistence provider
implementation.
Telling seam about a different JPA provider can be be done in one of two ways:
Update your application's components.xml so that the generic PersistenceProvider takes
precedence over the hibernate version. Simply add the following to the file:
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Configuring Seam in Java EE 5
<component name="org.jboss.seam.persistence.persistenceProvider"
class="org.jboss.seam.persistence.PersistenceProvider"
scope="stateless">
</component>
If you want to take advantage of your JPA provider's non-standard features you will need to write
you own implementation of the PersistenceProvider. Use HibernatePersistenceProvider
as a starting point (don't forget to give back to the community :). Then you will need to tell seam
to use it as before.
<component name="org.jboss.seam.persistence.persistenceProvider"
class="org.your.package.YourPersistenceProvider">
</component>
All that is left is updating the persistence.xml file with the correct provider class, and what
ever properties your provider needs. Don't forget to package your new provider's jar files in the
application if they are needed.
26.3. Configuring Seam in Java EE 5
If you're running in a Java EE 5 environment, this is all the configuration required to start using
Seam!
26.3.1. Packaging
Once you've packaged all this stuff together into an EAR, the archive structure will look something
like this:
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my-application.ear/
jboss-seam.jar
lib/
jboss-el.jar
META-INF/
MANIFEST.MF
application.xml
my-application.war/
META-INF/
MANIFEST.MF
WEB-INF/
web.xml
components.xml
faces-config.xml
lib/
jsf-facelets.jar
jboss-seam-ui.jar
login.jsp
register.jsp
...
my-application.jar/
META-INF/
MANIFEST.MF
persistence.xml
seam.properties
org/
jboss/
myapplication/
User.class
Login.class
LoginBean.class
Register.class
RegisterBean.class
...
You should declare jboss-seam.jar as an ejb module in META-INF/application.xml; jbossel.jar should be placed in the EAR's lib directory (putting it in the EAR classpath.
If you want to use jBPM or Drools, you must include the needed jars in the EAR's lib directory.
If you want to use facelets (our recommendation), you must include jsf-facelets.jar in the
WEB-INF/lib directory of the WAR.
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If you want to use the Seam tag library (most Seam applications do), you must include jbossseam-ui.jar in the WEB-INF/lib directory of the WAR. If you want to use the PDF or email tag
libraries, you need to put jboss-seam-pdf.jar or jboss-seam-mail.jar in WEB-INF/lib.
If you want to use the Seam debug page (only works for applications using facelets), you must
include jboss-seam-debug.jar in the WEB-INF/lib directory of the WAR.
Seam ships with several example applications that are deployable in any Java EE container that
supports EJB 3.0.
I really wish that was all there was to say on the topic of configuration but unfortunately we're only
about a third of the way there. If you're too overwhelmed by all this tedious configuration stuff, feel
free to skip over the rest of this section and come back to it later.
26.4. Configuring Seam in J2EE
Seam is useful even if you're not yet ready to take the plunge into EJB 3.0. In this case you would
use Hibernate3 or JPA instead of EJB 3.0 persistence, and plain JavaBeans instead of session
beans. You'll miss out on some of the nice features of session beans but it will be very easy to
migrate to EJB 3.0 when you're ready and, in the meantime, you'll be able to take advantage of
Seam's unique declarative state management architecture.
Seam JavaBean components do not provide declarative transaction demarcation like session
beans do. You could manage your transactions manually using the JTA UserTransaction or
declaratively using Seam's @Transactional annotation. But most applications will just use Seam
managed transactions when using Hibernate with JavaBeans.
The Seam distribution includes a version of the booking example application that uses Hibernate3
and JavaBeans instead of EJB3, and another version that uses JPA and JavaBeans. These
example applications are ready to deploy into any J2EE application server.
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26.4.1. Boostrapping Hibernate in Seam
Seam will bootstrap a Hibernate SessionFactory from your hibernate.cfg.xml file if you install
a built-in component:
<persistence:hibernate-session-factory name="hibernateSessionFactory"/>
You will also need to configure a managed session if you want a Seam managed Hibernate
Session to be available via injection.
<persistence:managed-hibernate-session name="hibernateSession"
session-factory="#{hibernateSessionFactory}"/>
26.4.2. Boostrapping JPA in Seam
Seam will bootstrap a JPA EntityManagerFactory from your persistence.xml file if you install
this built-in component:
<persistence:entity-manager-factory name="entityManagerFactory"/>
You will also need to configure a managed persistence context if you want a Seam managed JPA
EntityManager to be available via injection.
<persistence:managed-persistence-context name="entityManager"
entity-manager-factory="#{entityManagerFactory}"/>
26.4.3. Packaging
We can package our application as a WAR, in the following structure:
my-application.war/
META-INF/
MANIFEST.MF
WEB-INF/
web.xml
components.xml
faces-config.xml
lib/
jboss-seam.jar
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Configuring Seam in Java SE, without JBoss
Embedded
jboss-seam-ui.jar
jboss-el.jar
jsf-facelets.jar
hibernate3.jar
hibernate-annotations.jar
hibernate-validator.jar
...
my-application.jar/
META-INF/
MANIFEST.MF
seam.properties
hibernate.cfg.xml
org/
jboss/
myapplication/
User.class
Login.class
Register.class
...
login.jsp
register.jsp
...
If we want to deploy Hibernate in a non-EE environment like Tomcat or TestNG, we need to do
a little bit more work.
26.5. Configuring Seam in Java SE, without JBoss
Embedded
It is possible to use Seam completely outside of an EE environment. In this case, you need to tell
Seam how to manage transactions, since there will be no JTA available. If you're using JPA, you
can tell Seam to use JPA resource-local transactions, ie. EntityTransaction, like so:
<transaction:entity-transaction entity-manager="#{entityManager}"/>
If you're using Hibernate, you can tell Seam to use the Hibernate transaction API like this:
<transaction:hibernate-transaction session="#{session}"/>
Of course, you'll also need to define a datasource.
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A better alternative is to use JBoss Embedded to get access to the EE APIs.
26.6. Configuring Seam in Java SE, with JBoss
Embedded
JBoss Embedded lets you run EJB3 components outside the context of the Java EE 5 application
server. This is especially, but not only, useful for testing.
The Seam booking example application includes a TestNG integration test suite that runs on
JBoss Embedded via SeamTest.
The booking example application may even be deployed to Tomcat.
26.6.1. Installing Embedded JBoss
Embedded JBoss must by installed into Tomcat for Seam applications to run correctly on it.
Embedded JBoss only runs on JDK 1.5 (not JDK 1.6). Embedded JBoss can be downloaded
here [http://sourceforge.net/project/showfiles.php?group_id=22866&package_id=228977]. The
process for installing Embedded JBoss into Tomcat 6 is quite simple. First, you should copy the
Embedded JBoss JARs and configuration files into Tomcat.
• Copy all files and directories under the Embedded JBoss bootstrap and lib directories, except
for the jndi.properties file, into the Tomcat lib directory.
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• Remove the annotations-api.jar file from the Tomcat lib directory.
Next, two configuration files need to be updated to add Embedded JBoss-specific functionality.
• Add the Embedded JBoss listener to conf/server.xml. It should appear after all other listeners
in the file.
<Listener className="org.jboss.embedded.tomcat.EmbeddedJBossBootstrapListener"/>
• WAR file scanning should be enabled by adding a listener to conf/context.xml.
<Listener className="org.jboss.embedded.tomcat.WebinfScanner"/>
For more configuration options, please see the Embedded JBoss Tomcat integration wiki entry
[http://wiki.jboss.org/wiki/Wiki.jsp?page=EmbeddedAndTomcat].
26.6.2. Packaging
The archive structure of a WAR-based deployment on an servlet engine like Tomcat will look
something like this:
my-application.war/
META-INF/
MANIFEST.MF
WEB-INF/
web.xml
components.xml
faces-config.xml
lib/
jboss-seam.jar
jboss-seam-ui.jar
jboss-el.jar
jsf-facelets.jar
jsf-api.jar
jsf-impl.jar
...
my-application.jar/
META-INF/
MANIFEST.MF
persistence.xml
seam.properties
org/
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jboss/
myapplication/
User.class
Login.class
LoginBean.class
Register.class
RegisterBean.class
...
login.jsp
register.jsp
...
Most of the Seam example applications may be deployed to Tomcat by running ant
deploy.tomcat.
26.7. Configuring jBPM in Seam
Seam's jBPM integration is not installed by default, so you'll need to enable jBPM by installing
a built-in component. You'll also need to explicitly list your process and pageflow definitions. In
components.xml:
<bpm:jbpm>
<bpm:pageflow-definitions>
<value>createDocument.jpdl.xml</value>
<value>editDocument.jpdl.xml</value>
<value>approveDocument.jpdl.xml</value>
</bpm:pageflow-definitions>
<bpm:process-definitions>
<value>documentLifecycle.jpdl.xml</value>
</bpm:process-definitions>
</bpm:jbpm>
No further special configuration is needed if you only have pageflows. If you do have business
process definitions, you need to provide a jBPM configuration, and a Hibernate configuration for
jBPM. The Seam DVD Store demo includes example jbpm.cfg.xml and hibernate.cfg.xml
files that will work with Seam:
<jbpm-configuration>
<jbpm-context>
<service name="persistence">
<factory>
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<bean class="org.jbpm.persistence.db.DbPersistenceServiceFactory">
<field name="isTransactionEnabled"><false/></field>
</bean>
</factory>
</service>
<service name="tx" factory="org.jbpm.tx.TxServiceFactory" />
<service name="message" factory="org.jbpm.msg.db.DbMessageServiceFactory" />
<service name="scheduler" factory="org.jbpm.scheduler.db.DbSchedulerServiceFactory" />
<service name="logging" factory="org.jbpm.logging.db.DbLoggingServiceFactory" />
<service name="authentication"
factory="org.jbpm.security.authentication.DefaultAuthenticationServiceFactory" />
</jbpm-context>
</jbpm-configuration>
The most important thing to notice here is that jBPM transaction control is disabled. Seam or EJB3
should control the JTA transactions.
26.7.1. Packaging
There is not yet any well-defined packaging format for jBPM configuration and process/pageflow
definition files. In the Seam examples we've decided to simply package all these files into the root
of the EAR. In future, we will probably design some other standard packaging format. So the EAR
looks something like this:
my-application.ear/
jboss-seam.jar
lib/
jboss-el.jar
jbpm-3.1.jar
META-INF/
MANIFEST.MF
application.xml
my-application.war/
META-INF/
MANIFEST.MF
WEB-INF/
web.xml
components.xml
faces-config.xml
lib/
jsf-facelets.jar
jboss-seam-ui.jar
login.jsp
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register.jsp
...
my-application.jar/
META-INF/
MANIFEST.MF
persistence.xml
seam.properties
org/
jboss/
myapplication/
User.class
Login.class
LoginBean.class
Register.class
RegisterBean.class
...
jbpm.cfg.xml
hibernate.cfg.xml
createDocument.jpdl.xml
editDocument.jpdl.xml
approveDocument.jpdl.xml
documentLifecycle.jpdl.xml
26.8. Configuring SFSB and Session Timeouts in JBoss
AS
It is very important that the timeout for Stateful Session Beans is set higher than the timeout
for HTTP Sessions, otherwise SFSB's may time out before the user's HTTP session has ended.
JBoss Application Server has a default session bean timeout of 30 minutes, which is configured
in server/default/conf/standardjboss.xml (replace default with your own configuration).
The default SFSB timeout can be adjusted by modifying the value of max-bean-life in the
LRUStatefulContextCachePolicy cache configuration:
<container-cache-conf>
<cache-policy>org.jboss.ejb.plugins.LRUStatefulContextCachePolicy</cache-policy>
<cache-policy-conf>
<min-capacity>50</min-capacity>
<max-capacity>1000000</max-capacity>
<remover-period>1800</remover-period>
<!-- SFSB timeout in seconds; 1800 seconds == 30 minutes -->
<max-bean-life>1800</max-bean-life>
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<overager-period>300</overager-period>
<max-bean-age>600</max-bean-age>
<resizer-period>400</resizer-period>
<max-cache-miss-period>60</max-cache-miss-period>
<min-cache-miss-period>1</min-cache-miss-period>
<cache-load-factor>0.75</cache-load-factor>
</cache-policy-conf>
</container-cache-conf>
The default HTTP session timeout can be modified in server/default/deploy/jbosswebtomcat55.sar/conf/web.xml for JBoss 4.0.x, or in server/default/deploy/jbossweb.deployer/conf/web.xml for JBoss 4.2.x. The following entry in this file controls the default
session timeout for all web applications:
<session-config>
<!-- HTTP Session timeout, in minutes -->
<session-timeout>30</session-timeout>
</session-config>
To override this value for your own application, simply include this entry in your application's own
web.xml.
26.9. Running Seam in a Portlet
If you want to run your Seam application in a portlet, take a look at the JBoss Portlet Bridge,
an implementation of JSR-301 that supports JSF within a portlet, with extensions for Seam and
RichFaces. See http://labs.jboss.com/portletbridge for more.
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Chapter 27.
Seam annotations
When you write a Seam application, you'll use a lot of annotations. Seam lets you use annotations
to achieve a declarative style of programming. Most of the annotations you'll use are defined by the
EJB 3.0 specification. The annotations for data validation are defined by the Hibernate Validator
package. Finally, Seam defines its own set of annotations, which we'll describe in this chapter.
All of these annotations are defined in the package org.jboss.seam.annotations.
27.1. Annotations for component definition
The first group of annotations lets you define a Seam component. These annotations appear on
the component class.
@Name
@Name("componentName")
Defines the Seam component name for a class. This annotation is required for all Seam
components.
@Scope
@Scope(ScopeType.CONVERSATION)
Defines the default context of the component. The possible values are defined by the
ScopeType enumeration: EVENT, PAGE, CONVERSATION, SESSION, BUSINESS_PROCESS,
APPLICATION, STATELESS.
When no scope is explicitly specified, the default depends upon the component type. For
stateless session beans, the default is STATELESS. For entity beans and stateful session
beans, the default is CONVERSATION. For JavaBeans, the default is EVENT.
@Role
@Role(name="roleName", scope=ScopeType.SESSION)
Allows a Seam component to be bound to multiple contexts variables. The @Name/@Scope
annotations define a "default role". Each @Role annotation defines an additional role.
• name — the context variable name.
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• scope — the context variable scope. When no scope is explicitly specified, the default
depends upon the component type, as above.
@Roles
@Roles({
@Role(name="user", scope=ScopeType.CONVERSATION),
@Role(name="currentUser", scope=ScopeType.SESSION)
})
Allows specification of multiple additional roles.
@BypassInterceptors
@BypassInterceptors
Disables Seam all interceptors on a particular component or method of a component.
@JndiName
@JndiName("my/jndi/name")
Specifies the JNDI name that Seam will use to look up the EJB component. If
no JNDI name is explicitly specified, Seam will use the JNDI pattern specified by
org.jboss.seam.core.init.jndiPattern.
@Conversational
@Conversational
Specifies that a conversation scope component is conversational, meaning that no method of
the component may be called unless a long-running conversation is active.
@PerNestedConversation
@PerNestedConversation
Limits the scope of a CONVERSATION-scoped component to just the parent conversation
in which it was instantiated. The component instance will not be visible to nested child
conversations, which will get their own instance.
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Annotations for component definition
Warning: this is ill-defined, since it implies that a component will be visible for some part of a
request cycle, and invisible after that. It is not recommended that applications use this feature!
@Startup
@Scope(APPLICATION) @Startup(depends="org.jboss.seam.bpm.jbpm")
Specifies that an application scope component is started immediately at initialization time.
This is mainly used for certain built-in components that bootstrap critical infrastructure such
as JNDI, datasources, etc.
@Scope(SESSION) @Startup
Specifies that a session scope component is started immediately at session creation time.
• depends — specifies that the named components must be started first, if they are installed.
@Install
@Install(false)
Specifies whether or not a component should be installed by default. The lack of an @Install
annotation indicates a component should be installed.
@Install(dependencies="org.jboss.seam.bpm.jbpm")
Specifies that a component should only be stalled if the components listed as dependencies
are also installed.
@Install(genericDependencies=ManagedQueueSender.class)
Specifies that a component should only be installed if a component that is implemented by a
certain class is installed. This is useful when the dependency doesn't have a single well-known
name.
@Install(classDependencies="org.hibernate.Session")
Specifies that a component should only be installed if the named class is in the classpath.
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@Install(precedence=BUILT_IN)
Specifies the precedence of the component. If multiple components with the same name exist,
the one with the higher precedence will be installed. The defined precendence values are (in
ascending order):
• BUILT_IN — Precedence of all built-in Seam components
• FRAMEWORK — Precedence to use for components of frameworks which extend Seam
• APPLICATION — Predence of application components (the default precedence)
• DEPLOYMENT — Precedence to use for components which override application components
in a particular deployment
• MOCK — Precedence for mock objects used in testing
@Synchronized
@Synchronized(timeout=1000)
Specifies that a component is accessed concurrently by multiple clients, and that Seam should
serialize requests. If a request is not able to obtain its lock on the component in the given
timeout period, an exception will be raised.
@ReadOnly
@ReadOnly
Specifies that a JavaBean component or component method does not require state replication
at the end of the invocation.
@AutoCreate
@AutoCreate
Specifies that a component will be automatically created, even if the client does not specify
create=true.
27.2. Annotations for bijection
The next two annotations control bijection. These attributes occur on component instance
variables or property accessor methods.
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Annotations for bijection
@In
@In
Specifies that a component attribute is to be injected from a context variable at the beginning
of each component invocation. If the context variable is null, an exception will be thrown.
@In(required=false)
Specifies that a component attribute is to be injected from a context variable at the beginning
of each component invocation. The context variable may be null.
@In(create=true)
Specifies that a component attribute is to be injected from a context variable at the beginning
of each component invocation. If the context variable is null, an instance of the component
is instantiated by Seam.
@In(value="contextVariableName")
Specifies the name of the context variable explicitly, instead of using the annotated instance
variable name.
@In(value="#{customer.addresses['shipping']}")
Specifies that a component attribute is to be injected by evaluating a JSF EL expression at
the beginning of each component invocation.
• value — specifies the name of the context variable. Default to the name of the component
attribute. Alternatively, specifies a JSF EL expression, surrounded by #{...}.
• create — specifies that Seam should instantiate the component with the same name as
the context variable if the context variable is undefined (null) in all contexts. Default to false.
• required — specifies Seam should throw an exception if the context variable is undefined
in all contexts.
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@Out
@Out
Specifies that a component attribute that is a Seam component is to be outjected to its context
variable at the end of the invocation. If the attribute is null, an exception is thrown.
@Out(required=false)
Specifies that a component attribute that is a Seam component is to be outjected to its context
variable at the end of the invocation. The attribute may be null.
@Out(scope=ScopeType.SESSION)
Specifies that a component attribute that is not a Seam component type is to be outjected to
a specific scope at the end of the invocation.
Alternatively, if no scope is explicitly specified, the scope of the component with the @Out
attribute is used (or the EVENT scope if the component is stateless).
@Out(value="contextVariableName")
Specifies the name of the context variable explicitly, instead of using the annotated instance
variable name.
• value — specifies the name of the context variable. Default to the name of the component
attribute.
• required — specifies Seam should throw an exception if the component attribute is null
during outjection.
Note that it is quite common for these annotations to occur together, for example:
@In(create=true) @Out private User currentUser;
The next annotation supports the manager component pattern, where a Seam component that
manages the lifecycle of an instance of some other class that is to be injected. It appears on a
component getter method.
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Annotations for bijection
@Unwrap
@Unwrap
Specifies that the object returned by the annotated getter method is the thing that is injected
instead of the component instance itself.
The next annotation supports the factory component pattern, where a Seam component is
responsible for initializing the value of a context variable. This is especially useful for initializing
any state needed for rendering the response to a non-faces request. It appears on a component
method.
@Factory
@Factory("processInstance") public void createProcessInstance() { ... }
Specifies that the method of the component is used to initialize the value of the named context
variable, when the context variable has no value. This style is used with methods that return
void.
@Factory("processInstance",
createProcessInstance() { ... }
scope=CONVERSATION)
public
ProcessInstance
Specifies that the method returns a value that Seam should use to initialize the value of
the named context variable, when the context variable has no value. This style is used with
methods that return a value. If no scope is explicitly specified, the scope of the component with
the @Factory method is used (unless the component is stateless, in which case the EVENT
context is used).
• value — specifies the name of the context variable. If the method is a getter method, default
to the JavaBeans property name.
• scope — specifies the scope that Seam should bind the returned value to. Only meaningful
for factory methods which return a value.
• autoCreate — specifies that this factory method should be automatically called whenever
the variable is asked for, even if @In does not specify create=true.
This annotation lets you inject a Log:
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@Logger
@Logger("categoryName")
Specifies
that
a
component field is to be injected with an instance
org.jboss.seam.log.Log. For entity beans, the field must be declared as static.
of
• value — specifies the name of the log category. Default to the name of the component
class.
The last annotation lets you inject a request parameter value:
@RequestParameter
@RequestParameter("parameterName")
Specifies that a component attribute is to be injected with the value of a request parameter.
Basic type conversions are performed automatically.
• value — specifies the name of the request parameter. Default to the name of the
component attribute.
27.3. Annotations for component lifecycle methods
These annotations allow a component to react to its own lifecycle events. They occur on methods
of the component. There may be only one of each per component class.
@Create
@Create
Specifies that the method should be called when an instance of the component is instantiated
by Seam. Note that create methods are only supported for JavaBeans and stateful session
beans.
@Destroy
@Destroy
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Annotations for context demarcation
Specifies that the method should be called when the context ends and its context variables are
destroyed. Note that destroy methods are only supported for JavaBeans and stateful session
beans.
Destroy methods should be used only for cleanup. Seam catches, logs and swallows any
exception that propagates out of a destroy method.
@Observer
@Observer("somethingChanged")
Specifies that the method should be called when a component-driven event of the specified
type occurs.
@Observer(value="somethingChanged",create=false)
Specifies that the method should be called when an event of the specified type occurs but
that an instance should not be created if one doesn't exist. If an instance does not exist and
create is false, the event will not be observed. The default value for create is true.
27.4. Annotations for context demarcation
These annotations provide declarative conversation demarcation. They appear on methods of
Seam components, usually action listener methods.
Every web request has a conversation context associated with it. Most of these conversations
end at the end of the request. If you want a conversation that span multiple requests, you must
"promote" the current conversation to a long-running conversation by calling a method marked
with @Begin.
@Begin
@Begin
Specifies that a long-running conversation begins when this method returns a non-null
outcome without exception.
@Begin(join=true)
Specifies that if a long-running conversation is already in progress, the conversation context
is simply propagated.
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@Begin(nested=true)
Specifies that if a long-running conversation is already in progress, a new nested conversation
context begins. The nested conversation will end when the next @End is encountered, and the
outer conversation will resume. It is perfectly legal for multiple nested conversations to exist
concurrently in the same outer conversation.
@Begin(pageflow="process definition name")
Specifies a jBPM process definition name that defines the pageflow for this conversation.
@Begin(flushMode=FlushModeType.MANUAL)
Specify
the
flush
mode
of
any
Seam-managed
persistence
contexts.
flushMode=FlushModeType.MANUAL supports the use of atomic conversations where all write
operations are queued in the conversation context until an explicit call to flush() (which
usually occurs at the end of the conversation).
• join — determines the behavior when a long-running conversation is already in progress.
If true, the context is propagated. If false, an exception is thrown. Default to false. This
setting is ignored when nested=true is specified.
• nested — specifies that a nested conversation should be started if a long-running
conversation is already in progress.
• flushMode — set the flush mode of any Seam-managed Hibernate sessions or JPA
persistence contexts that are created during this conversation.
• pageflow — a process definition name of a jBPM process definition deployed via
org.jboss.seam.bpm.jbpm.pageflowDefinitions.
@End
@End
Specifies that a long-running conversation ends when this method returns a non-null outcome
without exception.
• beforeRedirect — by default, the conversation will not actually be destroyed until after
any redirect has occurred. Setting beforeRedirect=true specifies that the conversation
should be destroyed at the end of the current request, and that the redirect will be processed
in a new temporary conversation context.
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Annotations for context demarcation
@StartTask
@StartTask
"Starts" a jBPM task. Specifies that a long-running conversation begins when this method
returns a non-null outcome without exception. This conversation is associated with the jBPM
task specified in the named request parameter. Within the context of this conversation, a
business process context is also defined, for the business process instance of the task
instance.
• The jBPM TaskInstance will be available in a request context variable named
taskInstance. The jPBM ProcessInstance will be available in a request context variable
named processInstance. (Of course, these objects are available for injection via @In.)
• taskIdParameter — the name of a request parameter which holds the id of the task. Default
to "taskId", which is also the default used by the Seam taskList JSF component.
• flushMode — set the flush mode of any Seam-managed Hibernate sessions or JPA
persistence contexts that are created during this conversation.
@BeginTask
@BeginTask
Resumes work on an incomplete jBPM task. Specifies that a long-running conversation
begins when this method returns a non-null outcome without exception. This conversation is
associated with the jBPM task specified in the named request parameter. Within the context
of this conversation, a business process context is also defined, for the business process
instance of the task instance.
• The jBPM org.jbpm.taskmgmt.exe.TaskInstance will be available in a request context
variable named taskInstance. The jPBM org.jbpm.graph.exe.ProcessInstance will be
available in a request context variable named processInstance.
• taskIdParameter — the name of a request parameter which holds the id of the task. Default
to "taskId", which is also the default used by the Seam taskList JSF component.
• flushMode — set the flush mode of any Seam-managed Hibernate sessions or JPA
persistence contexts that are created during this conversation.
@EndTask
@EndTask
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"Ends" a jBPM task. Specifies that a long-running conversation ends when this method
returns a non-null outcome, and that the current task is complete. Triggers a jBPM transition.
The actual transition triggered will be the default transition unless the application has called
Transition.setName() on the built-in component named transition.
@EndTask(transition="transitionName")
Triggers the given jBPM transition.
• transition — the name of the jBPM transition to be triggered when ending the task.
Defaults to the default transition.
• beforeRedirect — by default, the conversation will not actually be destroyed until after
any redirect has occurred. Setting beforeRedirect=true specifies that the conversation
should be destroyed at the end of the current request, and that the redirect will be processed
in a new temporary conversation context.
@CreateProcess
@CreateProcess(definition="process definition name")
Creates a new jBPM process instance when the method returns a non-null outcome without
exception. The ProcessInstance object will be available in a context variable named
processInstance.
• definition
—
the
name
of
the
jBPM
process
definition
deployed
via
org.jboss.seam.bpm.jbpm.processDefinitions.
@ResumeProcess
@ResumeProcess(processIdParameter="processId")
Re-enters the scope of an existing jBPM process instance when the method returns a nonnull outcome without exception. The ProcessInstance object will be available in a context
variable named processInstance.
• processIdParameter — the name a request parameter holding the process id. Default to
"processId".
@Transition
@Transition("cancel")
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Annotations for use with Seam JavaBean
components in a J2EE environment
Marks a method as signalling a transition in the current jBPM process instance whenever the
method returns a non-null result.
27.5. Annotations for use with Seam JavaBean
components in a J2EE environment
Seam provides an annotation that lets you force a rollback of the JTA transaction for certain action
listener outcomes.
@Transactional
@Transactional
Specifies that a JavaBean component should have a similar transactional behavior to the
default behavior of a session bean component. ie. method invocations should take place in
a transaction, and if no transaction exists when the method is called, a transaction will be
started just for that method. This annotation may be applied at either class or method level.
Do not use this annotation on EJB 3.0 components, use @TransactionAttribute!
@ApplicationException
@ApplicationException
Synonym for javax.ejb.ApplicationException, for use in a pre Java EE 5 environment. Applied
to an exception to denote that it is an application exception and should be reported to the
client directly(i.e., unwrapped).
Do
not
use
this
annotation
on
EJB
3.0
components,
use
@javax.ejb.ApplicationException instead.
• rollback — by default false, if true this exception should set the transaction to rollback
only
• end — by default false, if true this exception should end the current long-running
conversation
@Interceptors
@Interceptors({DVDInterceptor, CDInterceptor})
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Synonym for javax.interceptors.Interceptors, for use in a pre Java EE 5 environment. Note
that this may only be used as a meta-annotation. Declares an ordered list of interceptors for
a class or method.
Do
not
use
this
annotations
on
@javax.interceptor.Interceptors instead.
EJB
3.0
components,
use
These annotations are mostly useful for JavaBean Seam components. If you use EJB 3.0
components, you should use the standard Java EE5 annotation.
27.6. Annotations for exceptions
These annotations let you specify how Seam should handle an exception that propagates out of
a Seam component.
@Redirect
@Redirect(viewId="error.jsp")
Specifies that the annotated exception causes a browser redirect to a specified view id.
• viewId — specifies the JSF view id to redirect to. You can use EL here.
• message — a message to be displayed, default to the exception message.
• end — specifies that the long-running conversation should end, default to false.
@HttpError
@HttpError(errorCode=404)
Specifies that the annotated exception causes a HTTP error to be sent.
• errorCode — the HTTP error code, default to 500.
• message — a message to be sent with the HTTP error, default to the exception message.
• end — specifies that the long-running conversation should end, default to false.
27.7. Annotations for Seam Remoting
Seam Remoting requires that the local interface of a session bean be annotated with the following
annotation:
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Annotations for Seam interceptors
@WebRemote
@WebRemote(exclude="path.to.exclude")
Indicates that the annotated method may be called from client-side JavaScript. The exclude
property is optional and allows objects to be excluded from the result's object graph (see the
Remoting chapter for more details).
27.8. Annotations for Seam interceptors
The following annotations appear on Seam interceptor classes.
Please refer to the documentation for the EJB 3.0 specification for information about the
annotations required for EJB interceptor definition.
@Interceptor
@Interceptor(stateless=true)
Specifies that this interceptor is stateless and Seam may optimize replication.
@Interceptor(type=CLIENT)
Specifies that this interceptor is a "client-side" interceptor that is called before the EJB
container.
@Interceptor(around={SomeInterceptor.class, OtherInterceptor.class})
Specifies that this interceptor is positioned higher in the stack than the given interceptors.
@Interceptor(within={SomeInterceptor.class, OtherInterceptor.class})
Specifies that this interceptor is positioned deeper in the stack than the given interceptors.
27.9. Annotations for asynchronicity
The following annotations are used to declare an asynchronous method, for example:
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@Asynchronous public void scheduleAlert(Alert alert, @Expiration Date date) { ... }
@Asynchronous public Timer scheduleAlerts(Alert alert,
@Expiration Date date,
@IntervalDuration long interval) { ... }
@Asynchronous
@Asynchronous
Specifies that the method call is processed asynchronously.
@Duration
@Duration
Specifies that a parameter of the asynchronous call is the duration before the call is processed
(or first processed for recurring calls).
@Expiration
@Expiration
Specifies that a parameter of the asynchronous call is the datetime at which the call is
processed (or first processed for recurring calls).
@IntervalDuration
@IntervalDuration
Specifies that an asynchronous method call recurs, and that the annotationed parameter is
duration between recurrences.
27.10. Annotations for use with JSF
The following annotations make working with JSF easier.
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Annotations for use with dataTable
@Converter
Allows a Seam component to act as a JSF converter. The annotated class must be a Seam
component, and must implement javax.faces.convert.Converter.
• id — the JSF converter id. Defaults to the component name.
• forClass — if specified, register this component as the default converter for a type.
@Validator
Allows a Seam component to act as a JSF validator. The annotated class must be a Seam
component, and must implement javax.faces.validator.Validator.
• id — the JSF validator id. Defaults to the component name.
27.10.1. Annotations for use with dataTable
The following annotations make it easy to implement clickable lists backed by a stateful session
bean. They appear on attributes.
@DataModel
@DataModel("variableName")
Outjects a property of type List, Map, Set or Object[] as a JSF DataModel into the scope
of the owning component (or the EVENT scope if the owning component is STATELESS). In the
case of Map, each row of the DataModel is a Map.Entry.
• value — name of the conversation context variable. Default to the attribute name.
• scope — if scope=ScopeType.PAGE is explicitly specified, the DataModel will be kept in the
PAGE context.
@DataModelSelection
@DataModelSelection
Injects the selected value from the JSF DataModel (this is the element of the underlying
collection, or the map value). If only one @DataModel attribute is defined for a component, the
selected value from that DataModel will be injected. Otherwise, the component name of each
@DataModel must be specified in the value attribute for each @DataModelSelection.
If PAGE scope is specified on the associated @DataModel, then, in addition to the DataModel
Selection being injected, the associated DataModel will also be injected. In this case, if the
property annotated with @DataModel is a getter method, then a setter method for the property
must also be part of the Business API of the containing Seam Component.
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• value — name of the conversation context variable. Not needed if there is exactly one
@DataModel in the component.
@DataModelSelectionIndex
@DataModelSelectionIndex
Exposes the selection index of the JSF DataModel as an attribute of the component (this is the
row number of the underlying collection, or the map key). If only one @DataModel attribute is
defined for a component, the selected value from that DataModel will be injected. Otherwise,
the component name of each @DataModel must be specified in the value attribute for each
@DataModelSelectionIndex.
• value — name of the conversation context variable. Not needed if there is exactly one
@DataModel in the component.
27.11. Meta-annotations for databinding
These meta-annotations make it possible to implement similar functionality to @DataModel and
@DataModelSelection for other datastructures apart from lists.
@DataBinderClass
@DataBinderClass(DataModelBinder.class)
Specifies that an annotation is a databinding annotation.
@DataSelectorClass
@DataSelectorClass(DataModelSelector.class)
Specifies that an annotation is a dataselection annotation.
27.12. Annotations for packaging
This annotation provides a mechanism for declaring information about a set of components that
are packaged together. It can be applied to any Java package.
@Namespace
@Namespace(value="http://jboss.com/products/seam/example/seampay")
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Annotations for integrating with the servlet
container
Specifies that components in the current package are associated with the given namespace.
The declared namespace can be used as an XML namespace in a components.xml file to
simplify application configuration.
@Namespace(value="http://jboss.com/products/seam/core", prefix="org.jboss.seam.core")
Specifies a namespace to associate with a given package. Additionally, it specifies a
component name prefix to be applied to component names specified in the XML file. For
example, an XML element named init that is associated with this namespace would be
understood to actually refer to a component named org.jboss.seam.core.init.
27.13. Annotations for integrating with the servlet
container
These annotations allow you to integrate your Seam components with the servlet container.
@Filter
Use the Seam component (which implements javax.servlet.Filter) annotated with
@Filter as a servlet filter. It will be executed by Seam's master filter.
•
@Filter(around={"seamComponent", "otherSeamComponent"})
Specifies that this filter is positioned higher in the stack than the given filters.
•
@Filter(within={"seamComponent", "otherSeamComponent"})
Specifies that this filter is positioned deeper in the stack than the given filters.
391
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Chapter 28.
Built-in Seam components
This chapter describes Seam's built-in components, and their configuration properties. The builtin components will be created even if they are not listed in your components.xml file, but if
you need to override default properties or specify more than one component of a certain type,
components.xml is used.
Note that you can replace any of the built in components with your own implementations simply
by specifying the name of one of the built in components on your own class using @Name.
Note also that even though all the built in components use a qualified name, most of them are
aliased to unqualified names by default. These aliases specify auto-create="true", so you do
not need to use create=true when injecting built-in components by their unqualified name.
28.1. Context injection components
The first set of built in components exist purely to support injection of various contextual objects.
For example, the following component instance variable would have the Seam session context
object injected:
@In private Context sessionContext;
org.jboss.seam.core.contexts
Component
that
provides
access
to
Seam
Context
org.jboss.seam.core.contexts.sessionContext['user'].
objects,
for
example
org.jboss.seam.faces.facesContext
Manager component for the FacesContext context object (not a true Seam context)
All of these components are always installed.
28.2. Utility components
These components are merely useful.
org.jboss.seam.faces.facesMessages
Allows faces success messages to propagate across a browser redirect.
• add(FacesMessage facesMessage) — add a faces message, which will be displayed
during the next render response phase that occurs in the current conversation.
• add(String messageTemplate) — add a faces message, rendered from the given
message template which may contain EL expressions.
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• add(Severity severity, String messageTemplate) — add a faces message, rendered
from the given message template which may contain EL expressions.
• addFromResourceBundle(String
key) — add a faces message, rendered from a
message template defined in the Seam resource bundle which may contain EL expressions.
• addFromResourceBundle(Severity severity, String key) — add a faces message,
rendered from a message template defined in the Seam resource bundle which may contain
EL expressions.
• clear() — clear all messages.
org.jboss.seam.faces.redirect
A convenient API for performing redirects with parameters (this is especially useful for
bookmarkable search results screens).
• redirect.viewId — the JSF view id to redirect to.
• redirect.conversationPropagationEnabled — determines whether the conversation
will propagate across the redirect.
• redirect.parameters — a map of request parameter name to value, to be passed in the
redirect request.
• execute() — perform the redirect immediately.
• captureCurrentRequest() — stores the view id and request parameters of the current
GET request (in the conversation context), for later use by calling execute().
org.jboss.seam.faces.httpError
A convenient API for sending HTTP errors.
org.jboss.seam.core.events
An API for raising events that can be observed via @Observer methods, or method bindings
in components.xml.
• raiseEvent(String type) — raise an event of a particular type and distribute to all
observers.
• raiseAsynchronousEvent(String
type) — raise an event to be processed
asynchronously by the EJB3 timer service.
• raiseTimedEvent(String type, ....) — schedule an event to be processed
asynchronously by the EJB3 timer service.
• addListener(String type, String methodBinding) — add an observer for a particular
event type.
org.jboss.seam.core.interpolator
An API for interpolating the values of JSF EL expressions in Strings.
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Components for internationalization and themes
• interpolate(String template) — scan the template for JSF EL expressions of the form
#{...} and replace them with their evaluated values.
org.jboss.seam.core.expressions
An API for creating value and method bindings.
• createValueBinding(String expression) — create a value binding object.
• createMethodBinding(String expression) — create a method binding object.
org.jboss.seam.core.pojoCache
Manager component for a JBoss Cache PojoCache instance.
• pojoCache.cfgResourceName — the name of the configuration file. Default to
treecache.xml.
All of these components are always installed.
28.3. Components for internationalization and themes
The next group of components make it easy to build internationalized user interfaces using Seam.
org.jboss.seam.core.locale
The Seam locale.
org.jboss.seam.international.timezone
The Seam timezone. The timezone is session scoped.
org.jboss.seam.core.resourceBundle
The Seam resource bundle. The resource bundle is stateless. The Seam resource bundle
performs a depth-first search for keys in a list of Java resource bundles.
org.jboss.seam.core.resourceLoader
The resource loader provides access to application resources and resource bundles.
• resourceLoader.bundleNames — the names of the Java resource bundles to search when
the Seam resource bundle is used. Default to messages.
org.jboss.seam.international.localeSelector
Supports selection of the locale either at configuration time, or by the user at runtime.
• select() — select the specified locale.
• localeSelector.locale — the actual java.util.Locale.
• localeSelector.localeString — the stringified representation of the locale.
• localeSelector.language — the language for the specified locale.
• localeSelector.country — the country for the specified locale.
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• localeSelector.variant — the variant for the specified locale.
• localeSelector.supportedLocales — a list of SelectItems representing the supported
locales listed in jsf-config.xml.
• localeSelector.cookieEnabled — specifies that the locale selection should be persisted
via a cookie.
org.jboss.seam.international.timezoneSelector
Supports selection of the timezone either at configuration time, or by the user at runtime.
• select() — select the specified locale.
• timezoneSelector.timezone — the actual java.util.TimeZone.
• timezoneSelector.timeZoneId — the stringified representation of the timezone.
• timezoneSelector.cookieEnabled — specifies that the timezone selection should be
persisted via a cookie.
org.jboss.seam.international.messages
A map containing internationalized messages rendered from message templates defined in
the Seam resource bundle.
org.jboss.seam.theme.themeSelector
Supports selection of the theme either at configuration time, or by the user at runtime.
• select() — select the specified theme.
• theme.availableThemes — the list of defined themes.
• themeSelector.theme — the selected theme.
• themeSelector.themes — a list of SelectItems representing the defined themes.
• themeSelector.cookieEnabled — specifies that the theme selection should be persisted
via a cookie.
org.jboss.seam.theme.theme
A map containing theme entries.
All of these components are always installed.
28.4. Components for controlling conversations
The next group of components allow control of conversations by the application or user interface.
org.jboss.seam.core.conversation
API for application control of attributes of the current Seam conversation.
• getId() — returns the current conversation id
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jBPM-related components
• isNested() — is the current conversation a nested conversation?
• isLongRunning() — is the current conversation a long-running conversation?
• getId() — returns the current conversation id
• getParentId() — returns the conversation id of the parent conversation
• getRootId() — returns the conversation id of the root conversation
• setTimeout(int timeout) — sets the timeout for the current conversation
• setViewId(String outcome) — sets the view id to be used when switching back to the
current conversation from the conversation switcher, conversation list, or breadcrumbs.
• setDescription(String
description) — sets the description of the current
conversation to be displayed in the conversation switcher, conversation list, or
breadcrumbs.
• redirect() — redirect to the last well-defined view id for this conversation (useful after
login challenges).
• leave() — exit the scope of this conversation, without actually ending the conversation.
• begin() — begin a long-running conversation (equivalent to @Begin).
• beginPageflow(String pageflowName) — begin a long-running conversation with a
pageflow (equivalent to @Begin(pageflow="...")).
• end() — end a long-running conversation (equivalent to @End).
• pop() — pop the conversation stack, returning to the parent conversation.
• root() — return to the root conversation of the conversation stack.
• changeFlushMode(FlushModeType
conversation.
flushMode) — change the flush mode of the
org.jboss.seam.core.conversationList
Manager component for the conversation list.
org.jboss.seam.core.conversationStack
Manager component for the conversation stack (breadcrumbs).
org.jboss.seam.faces.switcher
The conversation switcher.
All of these components are always installed.
28.5. jBPM-related components
These components are for use with jBPM.
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org.jboss.seam.pageflow.pageflow
API control of Seam pageflows.
• isInProcess() — returns true if there is currently a pageflow in process
• getProcessInstance() — returns jBPM ProcessInstance for the current pageflow
• begin(String
conversation
pageflowName) — begin a pageflow in the context of the current
• reposition(String nodeName) — reposition the current pageflow to a particular node
org.jboss.seam.bpm.actor
API for application control of attributes of the jBPM actor associated with the current session.
• setId(String actorId) — sets the jBPM actor id of the current user.
• getGroupActorIds() — returns a Set to which jBPM actor ids for the current users groups
may be added.
org.jboss.seam.bpm.transition
API for application control of the jBPM transition for the current task.
• setName(String transitionName) — sets the jBPM transition name to be used when the
current task is ended via @EndTask.
org.jboss.seam.bpm.businessProcess
API for programmatic control of the association between the conversation and business
process.
• businessProcess.taskId — the id of the task associated with the current conversation.
• businessProcess.processId — the id of the process associated with the current
conversation.
• businessProcess.hasCurrentTask() — is a task instance associated with the current
conversation?
• businessProcess.hasCurrentProcess() — is a process instance associated with the
current conversation.
• createProcess(String name) — create an instance of the named process definition and
associate it with the current conversation.
• startTask() — start the task associated with the current conversation.
• endTask(String
conversation.
transitionName) — end the task associated with the current
• resumeTask(Long id) — associate the task with the given id with the current conversation.
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Security-related components
• resumeProcess(Long id) — associate the process with the given id with the current
conversation.
• transition(String transitionName) — trigger the transition.
org.jboss.seam.bpm.taskInstance
Manager component for the jBPM TaskInstance.
org.jboss.seam.bpm.processInstance
Manager component for the jBPM ProcessInstance.
org.jboss.seam.bpm.jbpmContext
Manager component for an event-scoped JbpmContext.
org.jboss.seam.bpm.taskInstanceList
Manager component for the jBPM task list.
org.jboss.seam.bpm.pooledTaskInstanceList
Manager component for the jBPM pooled task list.
org.jboss.seam.bpm.taskInstanceListForType
Manager component for the jBPM task lists.
org.jboss.seam.bpm.pooledTask
Action handler for pooled task assignment.
org.jboss.seam.bpm.processInstanceFinder
Manager for the process instance task list.
org.jboss.seam.bpm.processInstanceList
The process instance task list.
All of these components are installed whenever the component org.jboss.seam.bpm.jbpm is
installed.
28.6. Security-related components
These components relate to web-tier security.
org.jboss.seam.web.userPrincipal
Manager component for the current user Principal.
org.jboss.seam.web.isUserInRole
Allows JSF pages to choose to render a control, depending upon the
roles available to the current principal. <h:commandButton
value="edit"
rendered="#{isUserInRole['admin']}"/>.
28.7. JMS-related components
These components are for use with managed TopicPublishers and QueueSenders (see below).
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org.jboss.seam.jms.queueSession
Manager component for a JMS QueueSession .
org.jboss.seam.jms.topicSession
Manager component for a JMS TopicSession .
28.8. Mail-related components
These components are for use with Seam's Email support
org.jboss.seam.mail.mailSession
Manager component for a JavaMail Session. The session can be either looked up in the JNDI
context (by setting the sessionJndiName property) or it can created from the configuration
options in which case the host is mandatory.
• org.jboss.seam.mail.mailSession.host — the hostname of the SMTP server to use
• org.jboss.seam.mail.mailSession.port — the port of the SMTP server to use
• org.jboss.seam.mail.mailSession.username — the username to use to connect to the
SMTP server.
• org.jboss.seam.mail.mailSession.password — the password to use to connect to the
SMTP server
• org.jboss.seam.mail.mailSession.debug — enable JavaMail debugging (very
verbose)
• org.jboss.seam.mail.mailSession.ssl — enable SSL connection to SMTP (will default
to port 465)
org.jboss.seam.mail.mailSession.tls — by default true, enable TLS support in the
mail session
• org.jboss.seam.mail.mailSession.sessionJndiName — name under which
javax.mail.Session is bound to JNDI. If supplied, all other properties will be ignored.
a
28.9. Infrastructural components
These components provide critical platform infrastructure. You can install a component which isn't
installed by default by setting install="true" on the component in components.xml.
org.jboss.seam.core.init
Initialization settings for Seam. Always installed.
• org.jboss.seam.core.init.jndiPattern — the JNDI pattern used for looking up
session beans
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Infrastructural components
• org.jboss.seam.core.init.debug — enable Seam debug mode. This should be set to
false when in production. You may see errors if the system is placed under any load and
debug is enabled.
• org.jboss.seam.core.init.clientSideConversations — if set to true, Seam will save
conversation context variables in the client instead of in the HttpSession.
• org.jboss.seam.core.init.userTransactionName — the JNDI name to use when
looking up the JTA UserTransaction object.
org.jboss.seam.core.manager
Internal component for Seam page and conversation context management. Always installed.
• org.jboss.seam.core.manager.conversationTimeout — the conversation context
timeout in milliseconds.
• org.jboss.seam.core.manager.concurrentRequestTimeout — maximum wait time for
a thread attempting to gain a lock on the long-running conversation context.
• org.jboss.seam.core.manager.conversationIdParameter — the request parameter
used to propagate the conversation id, default to conversationId.
• org.jboss.seam.core.manager.conversationIsLongRunningParameter
—
the
request parameter used to propagate information about whether the conversation is longrunning, default to conversationIsLongRunning.
org.jboss.seam.navigation.pages
Internal component for Seam workspace management. Always installed.
• org.jboss.seam.navigation.pages.noConversationViewId — global setting for the
view id to redirect to when a conversation entry is not found on the server side.
• org.jboss.seam.navigation.pages.loginViewId — global setting for the view id to
redirect to when an unauthenticated user tries to access a protected view.
• org.jboss.seam.navigation.pages.httpPort — global setting for the port to use when
the http scheme is requested.
• org.jboss.seam.navigation.pages.httpsPort — global setting for the port to use when
the https scheme is requested.
• org.jboss.seam.navigation.pages.resources — a list of resources to search for
pages.xml style resources. Defaults to WEB-INF/pages.xml.
org.jboss.seam.bpm.jbpm
Bootstraps a JbpmConfiguration. Install as class org.jboss.seam.bpm.Jbpm.
• org.jboss.seam.bpm.jbpm.processDefinitions — a list of resource names of jPDL files
to be used for orchestration of business processes.
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• org.jboss.seam.bpm.jbpm.pageflowDefinitions — a list of resource names of jPDL
files to be used for orchestration of conversation page flows.
org.jboss.seam.core.conversationEntries
Internal session-scoped component recording the active long-running conversations between
requests.
org.jboss.seam.faces.facesPage
Internal page-scoped component recording the conversation context associated with a page.
org.jboss.seam.persistence.persistenceContexts
Internal component recording the persistence contexts which were used in the current
conversation.
org.jboss.seam.jms.queueConnection
Manages a JMS QueueConnection. Installed whenever managed managed QueueSender is
installed.
• org.jboss.seam.jms.queueConnection.queueConnectionFactoryJndiName — the
JNDI name of a JMS QueueConnectionFactory. Default to UIL2ConnectionFactory
org.jboss.seam.jms.topicConnection
Manages a JMS TopicConnection. Installed whenever managed managed TopicPublisher
is installed.
• org.jboss.seam.jms.topicConnection.topicConnectionFactoryJndiName — the
JNDI name of a JMS TopicConnectionFactory. Default to UIL2ConnectionFactory
org.jboss.seam.persistence.persistenceProvider
Abstraction layer for non-standardized features of JPA provider.
org.jboss.seam.core.validators
Caches instances of Hibernate Validator ClassValidator.
org.jboss.seam.faces.validation
Allows the application to determine whether validation failed or was successful.
org.jboss.seam.debug.introspector
Support for the Seam Debug Page.
org.jboss.seam.debug.contexts
Support for the Seam Debug Page.
org.jboss.seam.exception.exceptions
Internal component for exception handling.
org.jboss.seam.transaction.transaction
API for controlling transactions and abstracting the underlying transaction management
implementation behind a JTA-compatible interface.
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Miscellaneous components
org.jboss.seam.faces.safeActions
Decides if an action expression in an incoming URL is safe. This is done by checking that the
action expression exists in the view.
28.10. Miscellaneous components
These components don't fit into
org.jboss.seam.async.dispatcher
Dispatcher stateless session bean for asynchronous methods.
org.jboss.seam.core.image
Image manipulation and interrogation.
org.jboss.seam.core.pojoCache
Manager component for a PojoCache instance.
org.jboss.seam.core.uiComponent
Manages a map of UIComponents keyed by component id.
28.11. Special components
Certain special Seam component classes are installable multiple times under names specified in
the Seam configuration. For example, the following lines in components.xml install and configure
two Seam components:
<component name="bookingDatabase"
class="org.jboss.seam.persistence.ManagedPersistenceContext">
<property name="persistenceUnitJndiName">java:/comp/emf/bookingPersistence</property>
</component>
<component name="userDatabase"
class="org.jboss.seam.persistence.ManagedPersistenceContext">
<property name="persistenceUnitJndiName">java:/comp/emf/userPersistence</property>
</component>
The Seam component names are bookingDatabase and userDatabase.
<entityManager>, org.jboss.seam.persistence.ManagedPersistenceContext
Manager component for a conversation scoped managed EntityManager with an extended
persistence context.
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• <entityManager>.entityManagerFactory — a value binding expression that evaluates to an
instance of EntityManagerFactory.
<entityManager>.persistenceUnitJndiName — the JNDI name of the entity manager
factory, default to java:/<managedPersistenceContext>.
<entityManagerFactory>, org.jboss.seam.persistence.EntityManagerFactory
Manages a JPA EntityManagerFactory. This is most useful when using JPA outside of an
EJB 3.0 supporting environment.
• entityManagerFactory.persistenceUnitName — the name of the persistence unit.
See the API JavaDoc for further configuration properties.
<session>, org.jboss.seam.persistence.ManagedSession
Manager component for a conversation scoped managed Hibernate Session.
• <session>.sessionFactory — a value binding expression that evaluates to an instance of
SessionFactory.
<session>.sessionFactoryJndiName — the JNDI name of the session factory, default to
java:/<managedSession>.
<sessionFactory>, org.jboss.seam.persistence.HibernateSessionFactory
Manages a Hibernate SessionFactory.
• <sessionFactory>.cfgResourceName — the path to the configuration file. Default to
hibernate.cfg.xml.
See the API JavaDoc for further configuration properties.
<managedQueueSender>, org.jboss.seam.jms.ManagedQueueSender
Manager component for an event scoped managed JMS QueueSender.
• <managedQueueSender>.queueJndiName — the JNDI name of the JMS queue.
<managedTopicPublisher>, org.jboss.seam.jms.ManagedTopicPublisher
Manager component for an event scoped managed JMS TopicPublisher.
• <managedTopicPublisher>.topicJndiName — the JNDI name of the JMS topic.
<managedWorkingMemory>, org.jboss.seam.drools.ManagedWorkingMemory
Manager component for a conversation scoped managed Drools WorkingMemory.
• <managedWorkingMemory>.ruleBase — a value expression that evaluates to an instance
of RuleBase.
<ruleBase>, org.jboss.seam.drools.RuleBase
Manager component for an application scoped Drools RuleBase. Note that this is not really
intended for production usage, since it does not support dynamic installation of new rules.
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Special components
• <ruleBase>.ruleFiles — a list of files containing Drools rules.
<ruleBase>.dslFile — a Drools DSL definition.
<entityHome>, org.jboss.seam.framework.EntityHome
<hibernateEntityHome>, org.jboss.seam.framework.HibernateEntityHome
<entityQuery>, org.jboss.seam.framework.EntityQuery
<hibernateEntityQuery>, org.jboss.seam.framework.HibernateEntityQuery
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Seam JSF controls
Seam includes a number of JSF controls that are useful for working with Seam. These are
intended to complement the built-in JSF controls, and controls from other third-party libraries. We
recommend JBoss RichFaces, and Apache MyFaces Trinidad tag libraries for use with Seam. We
do not recommend the use of the Tomahawk tag library.
29.1. Tags
To use these tags, define the "s" namespace in your page as follows (facelets only):
<html xmlns="http://www.w3.org/1999/xhtml"
xmlns:s="http://jboss.com/products/seam/taglib">
The ui example demonstrates the use of a number of these tags.
29.1.1. Navigation Controls
29.1.1.1. <s:button>
Description
A button that supports invocation of an action with control over conversation propagation. Does
not submit the form.
Attributes
• value — the label.
• action — a method binding that specified the action listener.
• view — the JSF view id to link to.
• fragment — the fragment identifier to link to.
• disabled — is the link disabled?
• propagation — determines the conversation propagation style: begin, join, nest, none or
end.
• pageflow — a pageflow definition to begin. (This is only useful when propagation="begin"
or propagation="join" is used).
Usage
<s:button id="cancel"
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value="Cancel"
action="#{hotelBooking.cancel}"/>
You can specify both view and action on <s:link />. In this case, the action wil be called once
the redirect to the specified view has occured.
29.1.1.2. <s:conversationId>
Description
Add the conversation id to JSF link or button (e.g. <h:commandLink /> , <s:button />).
Attributes
None
29.1.1.3. <s:taskId>
Description
Add the task id to an output link (or similar JSF control), when the task is available via #{task}.
Attributes
None.
29.1.1.4. <s:link>
Description
A link that supports invocation of an action with control over conversation propagation. Does not
submit the form.
Attributes
• value — the label.
• action — a method binding that specified the action listener.
• view — the JSF view id to link to.
• fragment — the fragment identifier to link to.
• disabled — is the link disabled?
• propagation — determines the conversation propagation style: begin, join, nest, none or
end.
• pageflow — a pageflow definition to begin. (This is only useful when using
propagation="begin" or propagation="join".)
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Usage
<s:link id="register" view="/register.xhtml"
value="Register New User"/>
You can specify both view and action on <s:link />. In this case, the action will be called once
the redirect to the specified view has occured.
29.1.1.5. <s:conversationPropagation>
Description
Customize the conversation propagation for a command link or button (or similar JSF control).
Facelets only.
Attributes
• type — determines the conversation propagation style: begin, join, nest, none or end.
• pageflow — a pageflow definition to begin. (This is only useful when using
propagation="begin" or propagation="join".)
Usage
<h:commandButton value="Apply" action="#{personHome.update}">
<s:conversationPropagation type="join" />
</h:commandButton>
29.1.1.6.
<s:defaultAction>
Description
Specify the default action to run when the form is submitted using the enter key.
Currently you can only nest it inside buttons (e.g. <h:commandButton />, <a:commandButton />
or <tr:commandButton />).
You must specify an id on the action source. You can only have one default action per form.
Attributes
None.
Usage
<h:commandButton id="foo" value="Foo" action="#{manager.foo}">
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<s:defaultAction />
</h:commandButton>
29.1.2. Converters and Validators
29.1.2.1. <s:convertDateTime>
Description
Perform date or time conversions in the Seam timezone.
Attributes
None.
Usage
<h:outputText value="#{item.orderDate}">
<s:convertDateTime type="both" dateStyle="full"/>
</h:outputText>
29.1.2.2. <s:convertEntity>
Description
Assigns an entity converter to the current component. This is primarily useful for radio button and
dropdown controls.
The converter works with any managed entity which has an @Id annotation - either simple or
composite.
Attributes
None.
Configuration
You must use Seam managed transactions (see Section 9.2, “Seam managed transactions”) with
<s:convertEntity />.
If your Managed Persistence Context isn't called entityManager, then you need to set it in
components.xml:
<component name="org.jboss.seam.ui.EntityConverter">
<property name="entityManager">#{em}</property>
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</component>
If you are using a Managed Hibernate Session then you need to set it in components.xml:
<component name="org.jboss.seam.ui.EntityConverter">
<property name="session">#{hibernateSession}</property>
</component>
If you want to use more than one entity manager with the entity converter, you can create a copy
of the entity converter for each entity manager in components.xml:
<component name="myEntityConverter" class="org.jboss.seam.ui.converter.EntityConverter">
<property name="entityManager">#{em}</property>
</component>
<h:selectOneMenu value="#{person.continent}">
<s:selectItems value="#{continents.resultList}" var="continent"
label="#{continent.name}" />
<f:converter converterId="myEntityConverter" />
</h:selectOneMenu>
Usage
<h:selectOneMenu value="#{person.continent}" required="true">
<s:selectItems value="#{continents.resultList}" var="continent"
label="#{continent.name}"
noSelectionLabel="Please Select..."/>
<s:convertEntity />
</h:selectOneMenu>
29.1.2.3. <s:convertEnum>
Description
Assigns an enum converter to the current component. This is primarily useful for radio button and
dropdown controls.
Attributes
None.
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Usage
<h:selectOneMenu value="#{person.honorific}">
<s:selectItems value="#{honorifics}" var="honorific"
label="#{honorific.label}"
noSelectionLabel="Please select" />
<s:convertEnum />
</h:selectOneMenu>
29.1.2.4. <s:validate>
Description
A non-visual control, validates a JSF input field against the bound property using Hibernate
Validator.
Attributes
None.
Usage
<h:inputText id="userName" required="true"
value="#{customer.userName}">
<s:validate />
</h:inputText>
<h:message for="userName" styleClass="error" />
29.1.2.5. <s:validateAll>
Description
A non-visual control, validates all child JSF input fields against their bound properties using
Hibernate Validator.
Attributes
None.
Usage
<s:validateAll>
<div class="entry">
<h:outputLabel for="username">Username:</h:outputLabel>
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Formatting
<h:inputText id="username" value="#{user.username}"
required="true"/>
<h:message for="username" styleClass="error" />
</div>
<div class="entry">
<h:outputLabel for="password">Password:</h:outputLabel>
<h:inputSecret id="password" value="#{user.password}"
required="true"/>
<h:message for="password" styleClass="error" />
</div>
<div class="entry">
<h:outputLabel for="verify">Verify Password:</h:outputLabel>
<h:inputSecret id="verify" value="#{register.verify}"
required="true"/>
<h:message for="verify" styleClass="error" />
</div>
</s:validateAll>
29.1.3. Formatting
29.1.3.1. <s:decorate>
Description
"Decorate" a JSF input field when validation fails or when required="true" is set.
Attributes
• template — the facelets template to use to decorate the component
#{invalid} and #{required} are available inside s:decorate; #{required} evaluates to true
if you have set the input component being decorated as required, and #{invalid} evaluates to
true if a validation error occurs.
Usage
<s:decorate template="edit.xhtml">
<ui:define name="label">Country:</ui:define>
<h:inputText value="#{location.country}" required="true"/>
</s:decorate>
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
xmlns:ui="http://java.sun.com/jsf/facelets"
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xmlns:h="http://java.sun.com/jsf/html"
xmlns:f="http://java.sun.com/jsf/core"
xmlns:s="http://jboss.com/products/seam/taglib">
<div>
<s:label styleClass="#{invalid?'error':''}">
<ui:insert name="label"/>
<s:span styleClass="required" rendered="#{required}">*</s:span>
</s:label>
<span class="#{invalid?'error':''}">
<s:validateAll>
<ui:insert/>
</s:validateAll>
</span>
<s:message styleClass="error"/>
</div>
</ui:composition>
29.1.3.2. <s:div>
Description
Render a HTML <div>.
Attributes
None.
Usage
<s:div rendered="#{selectedMember == null}">
Sorry, but this member does not exist.
</s:div>
29.1.3.3. <s:span>
Description
Render a HTML <span>.
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Formatting
Attributes
None.
Usage
<s:span styleClass="required" rendered="#{required}">*</s:span>
29.1.3.4. <s:fragment>
Description
A non-rendering component useful for enabling/disabling rendering of it's children.
Attributes
None.
Usage
<s:fragment rendered="#{auction.highBidder ne null}">
Current bid:
</s:fragment>
29.1.3.5. <s:label>
Description
"Decorate" a JSF input field with the label. The label is placed inside the HTML <label> tag, and
is associated with the nearest JSF input component. It is often used with <s:decorate>.
Attributes
• style — The control's style
• styleClass — The control's style class
Usage
<s:label styleClass="label">
Country:
</s:label>
<h:inputText value="#{location.country}" required="true"/>
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29.1.3.6. <s:message>
Description
"Decorate" a JSF input field with the validation error message.
Attributes
None.
Usage
<f:facet name="afterInvalidField">
<s:span>
&#160;Error:&#160;
<s:message/>
</s:span>
</f:facet>
29.1.4. Seam Text
29.1.4.1. <s:validateFormattedText>
Description
Checks that the submitted value is valid Seam Text
Attributes
None.
29.1.4.2. <s:formattedText>
Description
Outputs Seam Text, a rich text markup useful for blogs, wikis and other applications that might
use rich text. See the Seam Text chapter for full usage.
Attributes
• value — an EL expression specifying the rich text markup to render.
Usage
<s:formattedText value="#{blog.text}"/>
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Example
29.1.5. Dropdowns
29.1.5.1. <s:enumItem>
Description
Creates a SelectItem from an enum value.
Attributes
• enumValue — the string representation of the enum value.
• label — the label to be used when rendering the SelectItem.
Usage
<h:selectOneRadio id="radioList"
layout="lineDirection"
value="#{newPayment.paymentFrequency}">
<s:convertEnum />
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<s:enumItem enumValue="ONCE"
label="Only Once" />
<s:enumItem enumValue="EVERY_MINUTE" label="Every Minute" />
<s:enumItem enumValue="HOURLY"
label="Every Hour" />
<s:enumItem enumValue="DAILY"
label="Every Day" />
<s:enumItem enumValue="WEEKLY"
label="Every Week" />
</h:selectOneRadio>
29.1.5.2. <s:selectItems>
Description
Creates a List<SelectItem> from a List, Set, DataModel or Array.
Attributes
• value — an EL expression specifying the data that backs the List<SelectItem>
• var— defines the name of the local variable that holds the current object during iteration
• label — the label to be used when rendering the SelectItem. Can reference the var variable.
• itemValue — Value to return to the server if this option is selected. Optional, by default the var
object is used. Can reference the var variable.
• disabled — if true the SelectItem will be rendered disabled. Can reference the var variable.
• noSelectionLabel — specifies the (optional) label to place at the top of list (if
required="true" is also specified then selecting this value will cause a validation error).
• hideNoSelectionLabel — if true, the noSelectionLabel will be hidden when a value is
selected
Usage
<h:selectOneMenu value="#{person.age}"
converter="ageConverter">
<s:selectItems value="#{ages}" var="age" label="#{age}" />
</h:selectOneMenu>
29.1.6. Other
29.1.6.1. <s:cache>
Description
Cache the rendered page fragment using JBoss Cache. Note that <s:cache> actually uses the
instance of JBoss Cache managed by the built-in pojoCache component.
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Other
Attributes
• key — the key to cache rendered content, often a value expression. For example, if we
were caching a page fragment that displays a document, we might use key="Document#{document.id}".
• enabled — a value expression that determines if the cache should be used.
• region — a JBoss Cache node to use (different nodes can have different expiry policies).
Usage
<s:cache key="entry-#{blogEntry.id}" region="pageFragments">
<div class="blogEntry">
<h3>#{blogEntry.title}</h3>
<div>
<s:formattedText value="#{blogEntry.body}"/>
</div>
<p>
[Posted on&#160;
<h:outputText value="#{blogEntry.date}">
<f:convertDateTime timezone="#{blog.timeZone}" locale="#{blog.locale}"
type="both"/>
</h:outputText>]
</p>
</div>
</s:cache>
29.1.6.2. <s:fileUpload>
Description
Renders a file upload control. This control must be used within a form with an encoding type of
multipart/form-data, i.e:
<h:form enctype="multipart/form-data">
For multipart requests, the Seam Multipart servlet filter must also be configured in web.xml:
<filter>
<filter-name>Seam Filter</filter-name>
<filter-class>org.jboss.seam.servlet.SeamFilter</filter-class>
</filter>
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<filter-mapping>
<filter-name>Seam Filter</filter-name>
<url-pattern>/*</url-pattern>
</filter-mapping>
Configuration
The following configuration options for multipart requests may be configured in components.xml:
• createTempFiles — if this option is set to true, uploaded files are streamed to a temporary
file instead of in memory.
• maxRequestSize — the maximum size of a file upload request, in bytes.
Here's an example:
<component class="org.jboss.seam.web.MultipartFilter">
<property name="createTempFiles">true</property>
<property name="maxRequestSize">1000000</property>
</component>
Attributes
• data — this value binding receives the binary file data. The receiving field should be declared
as a byte[] or InputStream (required).
• contentType — this value binding receives the file's content type (optional).
• fileName — this value binding receives the filename (optional).
• fileSize — this value binding receives the file size (optional).
• accept — a comma-separated list of content types to accept, may not be supported by the
browser. E.g. "images/png,images/jpg", "images/*".
• style — The control's style
• styleClass — The control's style class
Usage
<s:fileUpload id="picture" data="#{register.picture}"
accept="image/png"
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Other
contentType="#{register.pictureContentType}" />
29.1.6.3. <s:graphicImage>
Description
An extended <h:graphicImage> that allows the image to be created in a Seam Component;
further transforms can be applied to the image.
All attributes for <h:graphicImage> are supported, as well as:
Attributes
• value — image to display. Can be a path String (loaded from the classpath), a byte[],
a java.io.File, a java.io.InputStream or a java.net.URL. Currently supported image
formats are image/png, image/jpeg and image/gif.
• fileName — if not specified the served image will have a generated file name. If you want to
name your file, you should specify it here. This name should be unique
Transformations
To apply a transform to the image, you would nest a tag specifying the transform to apply. Seam
currently supports these transforms:
<s:transformImageSize>
• width — new width of the image
• height — new height of the image
• maintainRatio — if true, and one of width/height are specified, the image will be resized
with the dimension not specified being calculated to maintain the aspect ratio.
• factor — scale the image by the given factor
<s:transformImageBlur>
• radius — perform a convolution blur with the given radius
<s:transformImageType>
• contentType — alter the type of the image to either image/jpeg or image/png
It's easy to create your own transform - create a UIComponent which implements
org.jboss.seam.ui.graphicImage.ImageTransform. Inside the applyTransform()method
use image.getBufferedImage() to get the original image and image.setBufferedImage() to
set your transformed image. Transforms are applied in the order specified in the view.
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Usage
<s:graphicImage rendered="#{auction.image ne null}"
value="#{auction.image.data}">
<s:transformImageSize width="200" maintainRatio="true"/>
</s:graphicImage>
29.1.6.4. <s:remote>
Description
Generates the Javascript stubs required to use Seam Remoting.
Attributes
• include — a comma-separated list of the component names (or fully qualified class names)for
which to generate Seam Remoting Javascript stubs. See Chapter 22, Remoting for more details.
Usage
<s:remote include="customerAction,accountAction,com.acme.MyBean"/>
29.2. Annotations
Seam also provides annotations to allow you to use Seam components as JSF converters and
validators:
@Converter
@Name("itemConverter")
@BypassInterceptors
@Converter
public class ItemConverter implements Converter {
@Transactional
public Object getAsObject(FacesContext context, UIComponent cmp, String value) {
EntityManager
entityManager
=
(EntityManager)
Component.getInstance("entityManager");
entityManager.joinTransaction();
// Do the conversion
}
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Annotations
public String getAsString(FacesContext context, UIComponent cmp, Object value) {
// Do the conversion
}
}
<h:inputText value="#{shop.item}" converter="itemConverter" />
Registers the Seam component as a JSF converter. Shown here is a converter which is able
to access the JPA EntityManager inside a JTA transaction, when converting the value back
to it's object representation.
@Validator
@Name("itemValidator")
@BypassInterceptors
@Validator
public class ItemValidator implements Validator {
public void validate(FacesContext context, UIComponent cmp, Object value)
throws ValidatorException {
ItemController ItemController = (ItemController) Component.getInstance("itemController");
return itemController.validate(value);
}
}
<h:inputText value="#{shop.item}" validator="itemValidator" />
Registers the Seam component as a JSF validator. Shown here is a validator which injects
another Seam component; the injected component is used to validate the value.
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Chapter 30.
JBoss EL
Seam uses JBoss EL which provides an extension to the standard Unified Expression Language
(EL). JBoss EL provides a number of enhancements that increase the expressiveness and power
of EL expressions.
30.1. Parameterized Expressions
Standard EL does not allow you to use a method with user defined parameters — of course, JSF
listener methods (e.g. a valueChangeListener) take parameters provided by JSF.
JBoss EL removes this restriction. For example:
<h:commandButton action="#{hotelBooking.bookHotel(hotel)}" value="Book Hotel"/>
@Name("hotelBooking")
public class HotelBooking {
public String bookHotel(Hotel hotel) {
// Book the hotel
}
}
30.1.1. Usage
Just as in calls to method from Java, parameters are surrounded by parentheses, and separated
by commas:
<h:commandButton action="#{hotelBooking.bookHotel(hotel, user)}" value="Book Hotel"/>
The parameters hotel and user will be evaluated as value expressions and passed to the
bookHotel() method of the component.
Any value expression may be used as a parameter:
<h:commandButton
action="#{hotelBooking.bookHotel(hotel.id, user.username)}"
value="Book Hotel"/>
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It's important to fully understand how this extension to EL works. When the page is rendered, the
parameter names are stored (for example, hotel.id and user.username), and evaluated (as
value expressions) when the page is submitted. You can't pass objects as parameters!
You must ensure that the parameters are available not only when the page is rendered, but also
when it is submittedIf the arguments can not be resolved when the page is submitted the action
method will be called with null arguments!
You can also pass literal strings using single quotes:
<h:commandLink action="#{printer.println('Hello world!')}" value="Hello"/>
Unified EL also supports value expressions, used to bind a field to a backing bean. Value
expressions use JavaBean naming conventions and expect a getter/setter pair. Often JSF expects
a value expression where only retrieval (get) is needed (e.g. the rendered attribute). Many objects,
however, don't have appropriately named property accessors or require parameters.
JBoss EL removes this restriction by allowing values to be retrieved using the method syntax.
For example:
<h:outputText value="#{person.name}" rendered="#{person.name.length() > 5}" />
You can access the size of a collection in a similar manner:
#{searchResults.size()}
In general any expression of the form #{obj.property} would be identical to the expression
#{obj.getProperty()}.
Parameters are also allowed. The following example calls the productsByColorMethod with a
literal string argument:
#{controller.productsByColor('blue')}
30.1.2. Limitations and Hints
When using JBoss EL you should keep the following points in mind:
• Incompatibility with JSP 2.1 — JBoss EL can't currently be used with JSP 2.1 as the compiler
rejects expressions with parameters in. So, if you want to use this extension with JSF 1.2, you
will need to use Facelets. The extension works correctly with JSP 2.0.
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Projection
• Use inside iterative components — Components like <c:forEach /> and <ui:repeat />iterate
over a List or array, exposing each item in the list to nested components. This works great if
you are selecting a row using a <h:commandButton /> or <h:commandLink />:
@Factory("items")
public List<Item> getItems() {
return entityManager.createQuery("select ...").getResultList();
}
<h:dataTable value="#{items}" var="item">
<h:column>
<h:commandLink value="Select #{item.name}" action="#{itemSelector.select(item})" />
</h:column>
</h:dataTable>
However if you want to use <s:link /> or <s:button /> you must expose the items
as a DataModel, and use a <dataTable /> (or equivalent from a component set like
<rich:dataTable /> ). Neither <s:link /> or <s:button /> submit the form (and therefore
produce a bookmarkable link) so a "magic" parameter is needed to recreate the item when the
action method is called. This magic parameter can only be added when a data table backed
by a DataModel is used.
• Calling a MethodExpression from Java code — Normally, when a MethodExpression is
created, the parameter types are passed in by JSF. In the case of a method binding, JSF
assumes that there are no parameters to pass. With this extension, we can't know the parameter
types until after the expression has been evaluated. This has two minor consequences:
• When you invoke a MethodExpression in Java code, parameters you pass may be ignored.
Parameters defined in the expression will take precedence.
• Ordinarily, it is safe to call methodExpression.getMethodInfo().getParamTypes() at any
time. For an expression with parameters, you must first invoke the MethodExpression before
calling getParamTypes().
Both of these cases are exceedingly rare and only apply when you want to invoke the
MethodExpression by hand in Java code.
30.2. Projection
JBoss EL supports a limited projection syntax. A projection expression maps a sub-expression
across a multi-valued (list, set, etc...) expression. For instance, the expression:
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Chapter 30. JBoss EL
#{company.departments}
might return a list of departments. If you only need a list of department names, your only option is
to iterate over the list to retrieve the values. JBoss EL allows this with a projection expression:
#{company.departments.{d|d.name}}
The subexpression is enclosed in braces. In this example, the expression d.name is evaluated
for each department, using d as an alias to the department object. The result of this expression
will be a list of String values.
Any valid expression can be used in an expression, so it would be perfectly valid to write the
following, assuming you had a use for the lengths of all the department names in a company:
#{company.departments.{d|d.size()}}
Projections can be nested. The following expression returns the last names of every employee
in every department:
#{company.departments.{d|d.employees.{emp|emp.lastName}}}
Nested projections can be slightly tricky, however. The following expression looks like it returns
a list of all the employees in all the departments:
#{company.departments.{d|d.employees}}
However, it actually returns a list containing a list of the employees for each individual department.
To combine the values, it is necessary to use a slightly longer expression:
#{company.departments.{d|d.employees.{e|e}}}
It is important to note that this syntax cannot be parsed by Facelets or JSP and thus cannot be
used in xhtml or JSP files. We anticipate that the projection syntax will change in future versions
of JBoss EL.
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Chapter 31.
Testing Seam applications
Most Seam applications will need at least two kinds of automated tests: unit tests, which test
a particular Seam component in isolation, and scripted integration tests which exercise all Java
layers of the application (that is, everything except the view pages).
Both kinds of tests are very easy to write.
31.1. Unit testing Seam components
All Seam components are POJOs. This is a great place to start if you want easy unit testing.
And since Seam emphasises the use of bijection for inter-component interactions and access
to contextual objects, it's very easy to test a Seam component outside of its normal runtime
environment.
Consider the following Seam Component which creates a statement of account for a customer:
@Stateless
@Scope(EVENT)
@Name("statementOfAccount")
public class StatementOfAccount {
@In(create=true) EntityManager entityManager
private double statementTotal;
@In
private Customer customer;
@Create
public void create() {
List<Invoice> invoices = entityManager
.createQuery("select invoice from Invoice invoice where invoice.customer = :customer")
.setParameter("customer", customer)
.getResultList();
statementTotal = calculateTotal(invoices);
}
public double calculateTotal(List<Invoice> invoices) {
double total = 0.0;
for (Invoice invoice: invoices)
{
double += invoice.getTotal();
}
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return total;
}
// getter and setter for statementTotal
}
We could write a unit test for the calculateTotal method (which tests the business logic of the
component) as follows:
public class StatementOfAccountTest {
@Test
public testCalculateTotal {
List<Invoice> invoices = generateTestInvoices(); // A test data generator
double statementTotal = new StatementOfAccount().calculateTotal(invoices);
assert statementTotal = 123.45;
}
}
You'll notice we aren't testing retrieving data from or persisting data to the database; nor are we
testing any functionality provided by Seam. We are just testing the logic of our POJOs. Seam
components don't usually depend directly upon container infrastructure, so most unit testing as
as easy as that!
However, if you want to test the entire application, read on.
31.2. Integration testing Seam components
Integration testing is slightly more difficult. In this case, we can't eliminate the container
infrastructure; indeed, that is part of what is being tested! At the same time, we don't want to be
forced to deploy our application to an application server to run the automated tests. We need to
be able to reproduce just enough of the container infrastructure inside our testing environment to
be able to exercise the whole application, without hurting performance too much.
The approach taken by Seam is to let you write tests that exercise your components while
running inside a pruned down container environment (Seam, together with the JBoss Embedded
container; n.b. JBoss Embedded requires JDK 1.5 and does not work with JDK 1.6).
public class RegisterTest extends SeamTest
{
@Test
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Using mocks in integration tests
public void testRegisterComponent() throws Exception
{
new ComponentTest() {
protected void testComponents() throws Exception
{
setValue("#{user.username}", "1ovthafew");
setValue("#{user.name}", "Gavin King");
setValue("#{user.password}", "secret");
assert invokeMethod("#{register.register}").equals("success");
assert getValue("#{user.username}").equals("1ovthafew");
assert getValue("#{user.name}").equals("Gavin King");
assert getValue("#{user.password}").equals("secret");
}
}.run();
}
...
}
31.2.1. Using mocks in integration tests
Occasionally, we need to be able to replace the implementation of some Seam component that
depends upon resources which are not available in the integration test environment. For example,
suppose we have some Seam component which is a facade to some payment processing system:
@Name("paymentProcessor")
public class PaymentProcessor {
public boolean processPayment(Payment payment) { .... }
}
For integration tests, we can mock out this component as follows:
@Name("paymentProcessor")
@Install(precedence=MOCK)
public class MockPaymentProcessor extends PaymentProcessor {
public boolean processPayment(Payment payment) {
return true;
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}
}
Since the MOCK precedence is higher than the default precedence of application components,
Seam will install the mock implementation whenever it is in the classpath. When deployed into
production, the mock implementation is absent, so the real component will be installed.
31.3. Integration testing Seam application user
interactions
An even harder problem is emulating user interactions. A third problem is where to put
our assertions. Some test frameworks let us test the whole application by reproducing user
interactions with the web browser. These frameworks have their place, but they are not appropriate
for use at development time.
SeamTest lets you write scripted tests, in a simulated JSF environment. The role of a scripted test
is to reproduce the interaction between the view and the Seam components. In other words, you
get to pretend you are the JSF implementation!
This approach tests everything except the view.
Let's consider a JSP view for the component we unit tested above:
<html>
<head>
<title>Register New User</title>
</head>
<body>
<f:view>
<h:form>
<table border="0">
<tr>
<td>Username</td>
<td><h:inputText value="#{user.username}"/></td>
</tr>
<tr>
<td>Real Name</td>
<td><h:inputText value="#{user.name}"/></td>
</tr>
<tr>
<td>Password</td>
<td><h:inputSecret value="#{user.password}"/></td>
</tr>
</table>
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interactions
<h:messages/>
<h:commandButton type="submit" value="Register" action="#{register.register}"/>
</h:form>
</f:view>
</body>
</html>
We want to test the registration functionality of our application (the stuff that happens when the
user clicks the Register button). We'll reproduce the JSF request lifecycle in an automated TestNG
test:
public class RegisterTest extends SeamTest
{
@Test
public void testRegister() throws Exception
{
new FacesRequest() {
@Override
protected void processValidations() throws Exception
{
validateValue("#{user.username}", "1ovthafew");
validateValue("#{user.name}", "Gavin King");
validateValue("#{user.password}", "secret");
assert !isValidationFailure();
}
@Override
protected void updateModelValues() throws Exception
{
setValue("#{user.username}", "1ovthafew");
setValue("#{user.name}", "Gavin King");
setValue("#{user.password}", "secret");
}
@Override
protected void invokeApplication()
{
assert invokeMethod("#{register.register}").equals("success");
}
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@Override
protected void renderResponse()
{
assert getValue("#{user.username}").equals("1ovthafew");
assert getValue("#{user.name}").equals("Gavin King");
assert getValue("#{user.password}").equals("secret");
}
}.run();
}
...
}
Notice that we've extended SeamTest, which provides a Seam environment for our components,
and written our test script as an anonymous class that extends SeamTest.FacesRequest, which
provides an emulated JSF request lifecycle. (There is also a SeamTest.NonFacesRequest for
testing GET requests.) We've written our code in methods which are named for the various JSF
phases, to emulate the calls that JSF would make to our components. Then we've thrown in
various assertions.
You'll find plenty of integration tests for the Seam example applications which demonstrate more
complex cases. There are instructions for running these tests using Ant, or using the TestNG
plugin for eclipse:
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interactions
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31.3.1. Configuration
If you used seam-gen to create your project you are ready to start writing tests. Otherwise you'll
need to setup the testing environment in your favorite build tool (e.g. ant, maven, eclipse).
First, lets look at the dependencies you need at a minimum:
Table 31.1.
Group Id
Artifact Id
Location in Seam
org.jboss.seam.embedded
hibernate-all
lib/test/hibernateall.jar
org.jboss.seam.embedded
jboss-embedded-all
lib/test/jboss-embeddedall.jar
org.jboss.seam.embedded
thirdparty-all
lib/test/thirdpartyall.jar
org.jboss.seam.embedded
jboss-embedded-api
lib/jboss-embeddedapi.jar
org.jboss.seam
jboss-seam
lib/jboss-seam.jar
org.jboss.el
jboss-el
lib/jboss-el.jar
javax.faces
jsf-api
lib/jsf-api.jar
javax.activation
javax.activation
lib/activation.jar
It's very important you don't put the compile time JBoss AS dependencies from lib/ (e.g. jbosssystem.jar) on the classpath, these will cause Embedded JBoss to not boot. So, just add the
dependencies (e.g. Drools, jBPM)you need as you go.
You also need to include the bootstrap/ directory on the classpath; bootstrap/ contains the
configuration for Embedded JBoss.
And, of course you need to put your built project and tests onto the classpath. Don't forget to put all
the correct configuration files for JPA and Seam onto the classpath as well.Seam asks Embedded
JBoss to deploy any resource (jar or directory) which has seam.properties in it's root. Therefore,
if you don't assemble a directory structure that resembles a deployable archive containing your
built project, you must put a seam.properties in each resource.
By default, a generated project will use the java:/DefaultDS (a built in HSQL datasource in
Embedded JBoss) for testing. If you want to use another datasource place the foo-ds.xml into
bootstrap/deploy directory.
31.3.2. Using SeamTest with another test framework
Seam provides TestNG support out of the box, but you can also use another test framework, such
as JUnit, if you want.
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You'll need to provide an implementation of AbstractSeamTest which does the following:
• Calls super.begin() before every test method.
• Calls super.end() after every test method.
• Calls super.setupClass() to setup integration test environment. This should be called before
any test methods are called.
• Calls super.cleanupClass() to clean up the integration test environment.
• Calls super.startSeam() to start Seam at the start of integration testing.
• Calls super.stopSeam() to cleanly shut down Seam at the end of integration testing.
31.3.3. Integration Testing with Mock Data
If you need to insert or clean data in your database before each test you can use Seam's integration
with DBUnit. To do this, extend DBUnitSeamTest rather than SeamTest.
You need to provide a dataset for DBUnit. IMPORTANT NOTE: DBUnit supports two formats for
dataset files, flat and XML. Seam's DBUnitSeamTest assumes the flat format is used, so please
ensure that your dataset is in this format also.
<dataset>
<ARTIST
id="1"
dtype="Band"
name="Pink Floyd" />
<DISC
id="1"
name="Dark Side of the Moon"
artist_id="1" />
</dataset>
and tell Seam about it by overriding prepareDBUnitOperations():
protected void prepareDBUnitOperations() {
beforeTestOperations.add(
new DataSetOperation("my/datasets/BaseData.xml")
);
}
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DataSetOperation defaults to DatabaseOperation.CLEAN_INSERT if no other operation is
specified as a constructor argument. The above example cleans all tables defined BaseData.xml,
then inserts all rows declared in BaseData.xml before each @Test method is invoked.
If
you
require
extra cleanup
afterTestOperations list.
after
a
test
method
executes,
add
operations
to
You need to tell DBUnit about the datasource you are using by setting a TestNG test parameter
named datasourceJndiName:
<parameter name="datasourceJndiName" value="java:/seamdiscsDatasource"/>
DBUnitSeamTest only works out of the box with HSQL as a datasource. If you want to use
another database, then you'll need to implement some extra methods. Read the javadoc on
DBUnitSeamTest for more.
31.3.4. Integration Testing Seam Mail
Warning! This feature is still under development.
It's very easy to integration test your Seam Mail:
public class MailTest extends SeamTest {
@Test
public void testSimpleMessage() throws Exception {
new FacesRequest() {
@Override
protected void updateModelValues() throws Exception {
setValue("#{person.firstname}", "Pete");
setValue("#{person.lastname}", "Muir");
setValue("#{person.address}", "[email protected]");
}
@Override
protected void invokeApplication() throws Exception {
MimeMessage renderedMessage = getRenderedMailMessage("/simple.xhtml");
assert renderedMessage.getAllRecipients().length == 1;
InternetAddress to = (InternetAddress) renderedMessage.getAllRecipients()[0];
assert to.getAddress().equals("[email protected]");
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}
}.run();
}
}
We create a new FacesRequest as normal. Inside the invokeApplication hook we render the
message using getRenderedMailMessage(viewId);, passing the viewId of the message to
render. The method returns the rendered message on which you can do your tests. You can of
course also use any of the standard JSF lifecycle methods.
There is no support for rendering standard JSF components so you can't test the content body
of the mail message easily.
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Chapter 32.
Seam tools
32.1. jBPM designer and viewer
The jBPM designer and viewer will let you design and view in a nice way your business processes
and your pageflows. This convenient tool is part of JBoss Eclipse IDE and more details can be
found in the jBPM's documentation (http://docs.jboss.com/jbpm/v3/gpd/)
32.1.1. Business process designer
This tool lets you design your own business process in a graphical way.
32.1.2. Pageflow viewer
This tool let you design to some extend your pageflows and let you build graphical views of them
so you can easily share and compare ideas on how it should be designed.
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Chapter 33.
Seam on OC4J
OC4J (Oracle Containers for Java) 11g (currently a "Technology Preview" release) is Oracle's
JEE5 application server. Seam application can be deployed to OC4J, but require some additional
configuration changes, and dependencies. This chapter will show you exactly what must be done.
We will start by looking at the building and deploying the JEE5 Hotel Booking example application
which comes with Seam. Then we will deploy a project generated by seam-gen . First a basic seamgen application with RichFaces ajax components, and facelets. Then expand that application to
include Seam security with Drools, JPA provided with hibernate, and automatic CRUD reverse
engineering of a MySQL database.
33.1. Installation and operation of OC4J
First we need to install the target container - OC4j. This chapter requires you to use OC4J 11g
Technology Preview (not OC4J 10g). You can download OC4J 11g from http://www.oracle.com/
technology/tech/java/oc4j/11/ [http://www.oracle.com/technology/tech/java/oc4j/11/] Below are
instructions to install. launch, access, and shutdown the 11g release. For further information on
installing OC4J, consult the readme.txt distributed with OC4J, or the OC4J installation guide and
release notes.
1. Download and unzip OC4J
2. Make sure you have $JAVA_HOME and $ORACLE_HOME set as environment variables (
$ORACLE_HOME is the directory to which you unzip OC4J). For further information on installing
OC4J, consult the readme.txt distributed with OC4J
3. Applications (ear/war) are deployed to the $ORACLE_HOME/j2ee/home/applications
directory.
Note that OC4J does not support hot deployment by default. This means every time you deploy
the application you must restart the server.
4. Start OC4J: $ORACLE_HOME/j2ee/home/java -jar -XX:MaxPermSize=256M oc4j.jar
You must override the default PermGen memory settings using above command. See
OC4J release notes [http://www.oracle.com/technology/tech/java/oc4j/11/oc4j-relnotes.html]
for details.
You will be asked to set the admin password if this is the first time you have started OC4J
5. Once deployed you can check out your applications at http://localhost:8888/<your-apppath>
6. You can stop the server by pressing CTRL-C in the console on which the server is running.
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33.2. The jee5/booking example
The jee5/booking example is based on the Hotel Booking example (which runs on JBoss AS).
Out of the box it is designed to run on Glassfish, but it's easy to build it for OC4J. It is located in
the $SEAM_DIST/examples/jee5/booking directory.
33.2.1. Booking Example Dependencies
First, lets look at the basic dependencies of the booking example. Armed with this knowledge we
can look at the extra dependencies requirements that OC4J adds.
We will show you how to get these dependencies into the application in Section 33.2.3, “ Building
the jee5/booking example ” below.
33.2.1.1. Core Seam dependencies
• jboss-seam.jar — We declare this as an EJB3 module (why? well Seam needs to be able to
interact with container managed transactions; this is implemented as an EJB3 Stateful Session
Bean)
• jboss-el.jar
• jboss-seam-ui.jar — Seam's JSF controls depend on Apache's commons-beanutils
• jboss-seam-debug.jar
• jsf-facelets.jar
• richfaces-api.jar , richfaces-impl.jar and richfaces-ui.jar — which requires
Apache commons-digester and commons-beanutils
33.2.1.2. Extra dependencies
• Hibernate — of course, we decided to use Hibernate as the JPA provider (rather than TopLink
Essentials which ships with OC4J).
To use Hibernate as your JPA provider you need the following jars:
• hibernate.jar
• hibernate-annotations.jar
• hibernate-entitymanager.jar
• hibernate-validator.jar
• jboss-common-core.jar
• commons-logging.jar
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Booking Example Dependencies
• commons-collections.jar
• Third party jars — various jars needed for seam and this example to run.
• javaasist.jar
• dom4j.jar
• cglib.jar
• asm.jar
• commons-beanutils.jar
• commons-digester.jar
• log4j.jar — This can be left out if you are not going to configure log4j. If it is packaged but
not configured logging will be hidden in oc4j.
• Extra OC4J jars — Running Seam on most application servers (such as JBoss AS or Glassfish)
you only need to include the dependencies for those bits of Seam you actually use (e.g. if you
use Seam Text you need to include ANTLR); but, on OC4J, due to its "interesting" classloading
you must always include them:
• hibernate-search.jar
• hibernate-common-annotations.jar — needed for hibernate search
• lucene-core.jar — needed for hibernate search
• antlr.jar — needed for Seam Text
• jbpm-jpdl.jar — needed for Seam's JBPM
• quartz.jar
• dbunit.jar — needed for some testing classes
• jboss-embedded-api.jar — needed for some testing classes
• Drools — needed for Seam Security. We aren't using Seam security with Drools, but have
to include it. Drools consists of 6 jars:
• drools-core.jar
• drools-compiler.jar
• janino.jar
• mvel141.jar
• core.jar
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• antlr-runtime.jar
Drools integration is not used in the example.
33.2.2. Configuration file changes
There are just a few changes to be made:
web.xml
You need to declare all your ejb's in the web.xml . This is a silly requirement of a number of
JEE5 application servers - for example OC4J and Glassfish.
This is already done in the example's web.xml file, below is an example.
<ejb-local-ref>
<ejb-ref-name>
jboss-seam-jee5/AuthenticatorAction/local
</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local>
org.jboss.seam.example.booking.Authenticator
</local>
<ejb-link>AuthenticatorAction</ejb-link>
</ejb-local-ref>
persistence.xml
You need to provide the correct configuration for your JPA implementation. We are using
Hibernate and due to OC4J bundling an old ANTLR, we need to use an alternative query
factory, we also want to use the OC4J transaction manager:
For our example modify the resources/META-INF/persistence.xml file. Comment out the
Glassfish properties and un-comment the OC4J properties.
<property name="hibernate.dialect"
value="org.hibernate.dialect.HSQLDialect"/>
<property name="hibernate.query.factory_class"
value="org.hibernate.hql.classic.ClassicQueryTranslatorFactory"/>
<property name="hibernate.transaction.manager_lookup_class"
value="org.hibernate.transaction.OrionTransactionManagerLookup"/>
33.2.3. Building the jee5/booking example
1. Modify the build.xml file in the example:
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• Un-comment the labeled OC4J-related library properties. This will include all the extra
dependencies discussed above.
It should look like the following:
<!-- add libs for oc4j (eager classloading) -->
<property name="jbpm.lib" value="true"/>
<property name="drools.lib" value="true"/>
<property name="quartz.lib" value="true" />
<property name="search.lib" value="true" />
<property name="dbunit.lib" value="true" />
<property name="jboss-embedded-api.lib" value="true" />
2. Build the demo app by running ant in the examples/jee5/booking directory. The build target
is dist/jboss-seam-jee5.ear
3. Copy dist/jboss-seam-jee5.ear following the instructions below.
33.3. Deploying the Seam application to OC4J
This mini-tutorial describes the (fairly tedious) steps required to deploy a JEE 5 application to
OC4J. It assumes you have already downloaded and installed it following the instructions in
Section 33.1, “Installation and operation of OC4J”. It also assumes you are deploying the jee5/
booking example, using the embedded hsqldb database. To deploy another application you would
need to alter the datasource and application name.
1. Copy hsqldb.jar to OC4J shared library directory: cp ../../seam-gen/lib/hsqldb.jar
$ORACLE_HOME/j2ee/home/applib/ (OC4J doesn't come with an embedded database so we
decided to use HSQLDB)
2. Edit the OC4J datasource file $ORACLE_HOME/j2ee/home/config/data-sources.xml and,
inside <data-sources> , add
<managed-data-source
connection-pool-name="jee5-connection-pool"
jndi-name="jdbc/__default"
name="jee5-managed-data-source" />
<connection-pool name="jee5-connection-pool">
<connection-factory
factory-class="org.hsqldb.jdbcDriver"
user="sa"
password=""
url="jdbc:hsqldb:." />
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</connection-pool>
The jndi-name is used as the jta-data-source in persistence.xml .
3. Edit $ORACLE_HOME/j2ee/home/config/server.xml and, inside <application-server> ,
add
<application name="jboss-seam-jee5"
path="../../home/applications/jboss-seam-jee5.ear"
parent="default"
start="true" />
To keep things simple use the same names as you used for project.
4. Edit $ORACLE_HOME/j2ee/home/config/default-web-site.xml , and, inside <web-site>
, add
<web-app application="jboss-seam-jee5"
name="jboss-seam-jee5"
load-on-startup="true"
root="/seam-jee5" />
The root is the context path you will put into your web browser to access the application.
5. Copy the application to OC4J: cp dist/jboss-seam-jee5.ear $ORACLE_HOME/j2ee/home/
applications/
6. Start/stop OC4J following instructions in Section 33.1, “Installation and operation of OC4J”
above.
7. Checkout the app at: http://localhost:8888/seam-jee5
33.4. Deploying an application created using seam-gen to
OC4J
seam-gen is a great tool for developers that can quickly get you up and running with a full Seam
application. However the project that it created is configured to run on JBoss AS. This means there
are some extra steps needed to have it execute on OC4j. The following explanation assumes you
are using the command line and a simple text editor, but of course you can use your favorite IDE.
seam-gen projects come with support for Eclipse and Netbeans.
We will start by creating and deploying a pretty simple application using seam-gen . Then
we'll show you how easy it is to use seam-gen and Hibernate Tools to reverse engineer a
database schema into a functional CRUD application. seam-gen will create JPA entity beans,
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Generating a basic seam-gen application
Seam Application Framework components and JSF views for you. We will also add Seam security
using Drools.
This tutorial uses MySQL (but of course you could use any database, altering the SQL and
datasources as appropriate); install, configure and run MySQL, then create a database with some
sample data. Don't forget to also download the mysql-connector-java-X.jar for jdbc support.
When setting up Seam security this tutorial will assume there is a table named User with columns
username and password with at least one entry. Beyond that you can set up any type of sample
data and tables you would like.
33.4.1. Generating a basic seam-gen application
First we need to tell the seam-gen what we want, run ./seam setup in the seam distribution
directory. Follow the settings example below based on your system and setup (ex. use your
database name instead of oc4jexample ).
> ./seam setup
Buildfile: build.xml
init:
setup:
[echo] Welcome to seam-gen :-)
[input] Enter your Java project workspace (the directory that contains your
Seam projects) [C:/Projects] [C:/Projects]
/home/jbalunas/workspace
[input] Enter your JBoss home directory [C:/Program Files/jboss-4.2.2.GA]
[C:/Program Files/jboss-4.2.2.GA]
/home/jbalunas/jboss/jboss-4.2.2.GA
[input] Enter the project name [myproject] [myproject]
oc4j_example
[echo] Accepted project name as: oc4j_example
[input] Select a RichFaces skin (not applicable if using ICEFaces) [blueSky]
([blueSky], classic, ruby, wine, deepMarine, emeraldTown, sakura, DEFAULT)
[input] Is this project deployed as an EAR (with EJB components) or a WAR
(with no EJB support) [ear] ([ear], war, )
[input] Enter the Java package name for your session beans [com.mydomain.
oc4j_example] [com.mydomain.oc4j_example]
org.jboss.seam.tutorial.oc4j.action
[input] Enter the Java package name for your entity beans [org.jboss.seam.
tutorial.oc4j.action] [org.jboss.seam.tutorial.oc4j.action]
org.jboss.seam.tutorial.oc4j.model
[input] Enter the Java package name for your test cases [org.jboss.seam.
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tutorial.oc4j.action.test] [org.jboss.seam.tutorial.oc4j.action.test]
org.jboss.seam.tutorial.oc4j.test
[input] What kind of database are you using? [hsql] ([hsql], mysql, oracle,
postgres, mssql, db2, sybase, enterprisedb, h2)
mysql
[input] Enter the Hibernate dialect for your database [org.hibernate.
dialect.MySQLDialect] [org.hibernate.dialect.MySQLDialect]
[input] Enter the filesystem path to the JDBC driver jar [lib/hsqldb.jar]
[lib/hsqldb.jar]
lib/mysql-connector.jar
[input] Enter JDBC driver class for your database [com.mysql.jdbc.Driver]
[com.mysql.jdbc.Driver]
[input] Enter the JDBC URL for your database [jdbc:mysql:///test]
[jdbc:mysql:///test]
jdbc:mysql:///oc4jexample
[input] Enter database username [sa] [sa]
username
[input] Enter database password [] []
password
[input] skipping input as property hibernate.default_schema.new has already
been set.
[input] Enter the database catalog name (it is OK to leave this blank) [] []
[input] Are you working with tables that already exist in the database? [n]
(y, [n], )
y
[input] Do you want to drop and recreate the database tables and data in
import.sql each time you deploy? [n] (y, [n], )
n
[input] Enter your ICEfaces home directory (leave blank to omit ICEfaces) [] []
[propertyfile] Creating new property file:
/home/jbalunas/workspace/jboss-seam/seam-gen/build.properties
[echo] Installing JDBC driver jar to JBoss server
[copy] Copying 1 file to /home/jbalunas/jboss/jboss-4.2.2.GA/server/default/lib
[echo] Type 'seam create-project' to create the new project
BUILD SUCCESSFUL
Type ./seam
new-project to create your project and cd
oc4j_example to the newly created project.
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Changes needed for deployment to OC4J
33.4.2. Changes needed for deployment to OC4J
We now need to make some changes to the generated project.
33.4.2.1. Configuration file changes
Let's start with the configuration files:
build.xml
• Change the default target to archive (we aren't going to cover automatic deployment to
OC4J).
<project name="oc4j_example" default="archive" basedir=".">
• OC4J looks for the drools file /security.drl file in the root of the war file instead of the root
of the ear file so we need to have the build.xml move it to the correct location at build time.
The following must be added at the top of the <target name="war" depends="compile"
description="Build the distribution .war file"> target.
<copy todir="${war.dir}">
<fileset dir="${basedir}/resources" >
<include name="*.drl" />
</fileset>
</copy>
resources/META-INF/persistence-dev.xml
• Alter the jta-data-source to be jdbc/__oc4jexample (and use this as the jndi-name
when creating the data source in data-sources.xml later during deployment).
• Add the properties (described in jee5/booking example):
<property name="hibernate.query.factory_class"
value="org.hibernate.hql.classic.ClassicQueryTranslatorFactory" />
<property name="hibernate.transaction.manager_lookup_class"
value="org.hibernate.transaction.OrionTransactionManagerLookup" />
<property name="hibernate.transaction.flush_before_completion"
value="true"/>
<property name="hibernate.cache.provider_class"
value="org.hibernate.cache.HashtableCacheProvider"/>
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• Remove the JBoss AS specific method of exposing the EntityManagerFactory:
<property
name="jboss.entity.manager.factory.jndi.name"
value="java:/oc4j_exampleEntityManagerFactory">
• You'll need to alter persistence-prod.xml as well if you want to deploy to OC4J using
the prod profile.
resources/META-INF/jboss-app.xml
You can delete this file as we aren't deploying to JBoss AS ( jboss-app.xml is used to enable
classloading isolation in JBoss AS)
resources/*-ds.xml
You can delete these file as we aren't deploying to JBoss AS (these files define datasources
in JBoss AS, in OC4J you have to edit the master data-sources.xml file)
resources/WEB-INF/components.xml
• Enable container managed transaction integration - add the
<transaction:ejbtransaction
/>
component,
and
it's
namespace
declaration
xmlns:transaction="http://jboss.com/products/seam/transaction"
• Alter the jndi-pattern to java:comp/env/oc4j_example/#{ejbName}/local
• We want to use a Seam Managed Persistence Context in our application. Unfortunately
OC4J doesn't expose the EntityManagerFactory in JNDI, but Seam provides a built-in
manager component. To activate add the following entry:
<persistence:entity-manager-factory
auto-create="true"
name="oc4jEntityManagerFactory"
persistence-unit-name="oc4j_example" />
We then need to tell Seam to use it, so we alter the managed-persistence-context
injecting the Entity Manager Factory into the existing element:
<persistence:managed-persistence-context
name="entityManager"
auto-create="true"
entity-manager-factory="#{oc4jEntityManagerFactory}" />
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Changes needed for deployment to OC4J
resources/WEB-INF/web.xml
You must add the Seam container managed transaction integration EJB entry below.
Remember for OC4j you need to declare all your EJBs here if you modify the application
further.
<ejb-local-ref>
<ejb-ref-name>
oc4j_example/EjbSynchronizations/local
</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local>
org.jboss.seam.transaction.LocalEjbSynchronizations
</local>
<ejb-link>EjbSynchronizations</ejb-link>
</ejb-local-ref>
resources/META-INF/orion-application.xml
• This is a file that you must create so that RichFaces and Ajax4Jsf stylesheets will work with
OC4J. This file basically tells OC4J not force its own inherited URL settings.
<?xml version = '1.0' encoding = 'utf-8'?>
<orion-application
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="http://xmlns.oracle.com/oracleas/schema/
orion-application-10_0.xsd"
schema-major-version="10"
schema-minor-version="0"
component-classification="internal">
<imported-shared-libraries>
<remove-inherited name="oracle.xml"/>
</imported-shared-libraries>
</orion-application>
• Now you need to tell the build.xml file that it needs to copy this file to the ear archive.
Find the <target name="ear" description="Build the EAR"> target and modify the
<copy todir="${ear.dir}/META-INF"> section to look like the following:
<copy todir="${ear.dir}/META-INF">
<fileset dir="${basedir}/resources/META-INF">
<include name="application.xml" />
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<include name="orion-application.xml"/>
<include name="jboss-app.xml" />
</fileset>
</copy>
33.4.2.2. Extra jar dependencies
This application has similar requirements as the jee5/booking example above.
The build.xml must be modified to add the jars listed below to the generated archive files. Look
for the <fileset dir="${basedir}"> section below and add the imports underneath the other
libraries being imported.
<target name="ear" description="Build the EAR">
<copy todir="${ear.dir}">
<fileset dir="${basedir}/resources">
<include name="*jpdl.xml" />
<include name="*hibernate.cfg.xml" />
<include name="jbpm.cfg.xml" />
<include name="*.drl" />
</fileset>
<fileset dir="${lib.dir}">
<include name="jboss-seam.jar" />
</fileset>
<fileset dir="${basedir}">
<include name="lib/jbpm*.jar" />
<include name="lib/jboss-el.jar" />
<include name="lib/drools-*.jar"/>
<include name="lib/janino*.jar"/>
<include name="lib/antlr-*.jar"/>
<include name="lib/mvel*.jar"/>
<include name="lib/richfaces-api*.jar" />
</fileset>
</copy>
<copy todir="${ear.dir}/META-INF">
<fileset dir="${basedir}/resources/META-INF">
<include name="application.xml" />
<include name="jboss-app.xml" />
</fileset>
</copy>
</target>
• Hibernate:
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Changes needed for deployment to OC4J
<include name="lib/hibernate.jar"/>
<include name="lib/hibernate-annotations.jar"/>
<include name="lib/hibernate-commons-annotations.jar"/>
<include name="lib/hibernate-entitymanager.jar"/>
<include name="lib/hibernate-search.jar"/>
<include name="lib/hibernate-validator.jar"/>
<include name="lib/commons-logging.jar"/>
<include name="lib/commons-collections.jar"/>
<include name="lib/jboss-common-core.jar"/>
• Drools — because we are using Drools to provide Seam Security rules, we need to add
in Eclipse JDT compiler (you don't need this on JBoss AS; again this is due to OC4J's
classloading):
<include name="lib/core.jar"/>
• Third party jars — most of these are only needed because of OC4J's classloading:
<include name="lib/javassist.jar"/>
<include name="lib/quartz.jar"/>
<include name="lib/dbunit.jar"/>
<include name="lib/jboss-embedded-api.jar"/>
<include name="lib/dom4j.jar"/>
<include name="lib/lucene-core.jar"/>
<include name="lib/cglib.jar"/>
<include name="lib/asm.jar"/>
<include name="lib/commons-beanutils.jar"/>
<include name="lib/commons-digester.jar"/>
<include name="lib/antlr.jar"/>
You should end up with something like:
<fileset dir="${basedir}">
<include name="lib/jbpm*.jar" />
<include name="lib/jboss-el.jar" />
<include name="lib/drools-*.jar"/>
<include name="lib/janino*.jar"/>
<include name="lib/antlr-*.jar"/>
<include name="lib/mvel*.jar"/>
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<include name="lib/richfaces-api*.jar" />
<include name="lib/hibernate.jar"/>
<include name="lib/hibernate-annotations.jar"/>
<include name="lib/hibernate-commons-annotations.jar"/>
<include name="lib/hibernate-entitymanager.jar"/>
<include name="lib/hibernate-search.jar"/>
<include name="lib/hibernate-validator.jar"/>
<include name="lib/commons-logging.jar"/>
<include name="lib/commons-collections.jar"/>
<include name="lib/jboss-common-core.jar"/>
<include name="lib/core.jar"/>
<include name="lib/javassist.jar"/>
<include name="lib/quartz.jar"/>
<include name="lib/dbunit.jar"/>
<include name="lib/jboss-embedded-api.jar"/>
<include name="lib/dom4j.jar"/>
<include name="lib/lucene-core.jar"/>
<include name="lib/cglib.jar"/>
<include name="lib/asm.jar"/>
<include name="lib/commons-beanutils.jar"/>
<include name="lib/commons-digester.jar"/>
<include name="lib/antlr.jar"/>
</fileset>
33.4.3. Building and deploying the seam-gen'd application to
OC4J
These instructions are very similar to the ones in Section 33.3, “Deploying the Seam application
to OC4J” but with the correct references for the oc4j_example application.
• Build your application by calling ant in the base directory of your project (ex. /home/jbalunas/
workspace/oc4j_example ). The target of the build will be dist/oc4j_example.ear .
• Copy the mysql-connector.jar file to the $ORACLE_HOME/j2ee/home/applib directory so that
jdbc drivers are available.
• $ORACLE_HOME/j2ee/home/config/data-sources.xml
<managed-data-source
connection-pool-name="oc4j-example-connection-pool"
jndi-name="jdbc/__oc4jexample"
name="oc4j-example-managed-data-source" />
<connection-pool
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Extending example with reverse engineered
CRUD and Drools
name="oc4j-example-connection-pool">
<connection-factory
factory-class="com.mysql.jdbc.Driver"
user="username"
password="password"
url="jdbc:mysql:///oc4j" />
</connection-pool>
• $ORACLE_HOME/j2ee/home/config/server.xml
<application name="oc4j_example"
path="../../home/applications/oc4j_example.ear"
parent="default"
start="true" />
• $ORACLE_HOME/j2ee/home/config/default-web-site.xml
<web-app application="oc4j_example"
name="oc4j_example"
load-on-startup="true"
root="/oc4j_example" />
• Start/stop OC4J following instructions in the Installation and operation of OC4J section
above.
• Checkout the app at: http://localhost:8888/oc4j_example
33.4.4. Extending example with reverse engineered CRUD and
Drools
In this section we extend the basic seam-gen application into a full blown CRUD application based
on an existing database. Plus we will add Drools based security as well.
33.4.4.1. Have seam-gen generate your CRUD applications
Type ./seam generate-entities in the base directory of your seam distribution. This will create
the entities, the Seam Application Framework classes and the relevant views for the CRUD
application.
That's it...no really...that's it. Build and deploy as before and see for yourself.
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33.4.4.2. Hook up drools authentication using your new CRUD
application
As stated above this section assumes your database had a User table with username and
password columns with at least one entry. If you don't have this you may need to modify the
authenticate method below.
Lets link our User entity into Seam Security by making our authenticator class a Stateless Session
Bean (OC4J is a EJB3 container after all!):
1. • Add the @Stateless annotation to the Authenticator class.
• Rename the class to AuthenticatorAction
• Create an interface called Authenticator which AuthenticatorAction implements (EJB3
requires session beans to have a local interface). Annotate the interface with @Local , and
add a single method with same signature as the authenticate in AuthenticatorAction .
@Name("authenticator") @Stateless public class
AuthenticatorAction implements Authenticator {
@Local public interface Authenticator {
public boolean authenticate();
}
2. Use @PersistenceContext to inject an EntityManager by adding this line the
AuthenticatorAction class:
@PersistenceContext private EntityManager entityManager;
3. Implement authenticate:
public boolean authenticate() {
List <User> users = entityManager .createQuery("select u from User u where
u.username = #{identity.username} and
u.password = #{identity.password}") .getResultList();
if (users.size() == 1) {
identity.addRole("admin");
return true;
} else {
return false;
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Finishing up
}
}
4. And then add the EJB3 reference to web.xml :
<ejb-local-ref>
<ejb-ref-name>
oc4j_example/AuthenticatorAction/local
</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local>
org.jboss.seam.tutorial.oc4j.action.Authenticator
</local>
<ejb-link>AuthenticatorAction</ejb-link>
</ejb-local-ref>
Build and deploy as before and notice that now only actual username and passwords are
accepted.
33.5. Finishing up
That's it, we're through. You now have a great starting point for any Seam based application
deployed to OC4J.
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Seam on BEA's Weblogic
Weblogic 10.X is BEA's JEE5 server offering, currently 10.0.MP1 is their stable release, and
10.3.TP is their latest tech preview release. Seam applications can be deployed and developed
on Weblogic servers, and this chapter will show you how. There are some known issues with the
Weblogic servers that will need to be worked around, and configuration changes that are needed.
First step is to get Weblogic downloaded, installed and running (no small feat). Then we'll talk
about Seam's JEE5 example and the hurdles to getting it running. After that, the JPA example will
be modified and deployed to the server. Then finally we will create a seam-gen application and
get it up and running to provide a jump start to your own application.
34.1. Installation and operation of Weblogic
First things first we need to get the server installed - and there is a choice to be made. Weblogic
10.0.MP1 is the most recent stable release, while 10.3.TP is a technical preview version that fixes
some things and breaks others.
• Weblogic
10.0.MP1
—
Download
showproduct.jsp?family=WLS&major=10&minor=1]
page
[http://commerce.bea.com/
10.0.MP1 has a known issue with EJBs that use varargs in their methods (it confuses them
as transient ). This causes exceptions when Weblogic attempts to compile the Seam EJBs.
There is a BEA support patch available to fix this issue, but BEA is currently working on a second
issue related to the EJBs. See the jee5/booking example for more details.
• Weblogic
10.3.TP
—
Download
page
[http://commerce.bea.com/
showproduct.jsp?family=WLS&major=10.3Tech&minor=-1&DL=www_WLS_103TechPreview_icon&WT.ac=DL_www_WLS_10.3_TechPreviewicon]
This version still has not fixed the varargs bug, and there is a new issue with EJBs that do not
use kodo (BEA's implementation of JPA). BEA has said that the varargs issue will be resolved
in the final version of 10.3, but the kodo issue is a blocker for getting the jee5/booking working.
Special jboss-seam.jar for Weblogic EJB Support
Starting with Seam 2.0.2.CR2 a special Weblogic specific jar has been created
that does not contain the TimerServiceDispatcher . This is the EJB that uses
varargs and exposes the second EJB issue. We will be using this jar for the jee5/
booking example, as it avoids both known BEA issues.
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34.1.1. Installing 10.0.MP1
Here are the quick steps to installing Weblogic 10.1.MP1. For more details or if you are having any
issues please check with the BEA docs at the Weblogic 10.0 Doc Center [http://e-docs.bea.com/
wls/docs100/index.html] . Here we install the RHEL 5 version using the graphical installer:
1. Follow the link given above for 10.0.MP1 and download the correct version for your
environment. You will need to sign up for an account with BEA in order to do this.
2. You may need to change the the server1001_XX.bin file to be executable:
chmod a+x server1001_XX.bin
3. Execute the install:
./server1001_XX.bin
4. When the graphical install loads, you need to set the BEA home location. This is where all BEA
applications are installed. This location will be known as $BEA_HOME in this document e.g.:
/jboss/apps/bea
5. Select Complete as the installation type. You do not need all the extras of the complete install
(such as struts and beehive libraries), but it will not hurt.
6. Then you need to tell it where to install the server components:
$BEA_HOME/wlserver_10.0
34.1.2. Creating your Weblogic domain
A Weblogic domain is similar to a JBoss server configuration - it is a self contained server instance.
The Weblogic server you just installed has some example domains, but we are going to create one
just for the seam examples. You can use the existing domains if you wish (modify the instructions
as needed).
1. Start up the Weblogic configuration wizard:
$BEA_HOME/wlserver_10.0/common/bin/config.sh
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2. Choose to create a new domain, configured to support Weblogic Server. Note that this is the
default domain option.
3. Set a username and password for this domain.
4. Next choose Development Mode and the default JDK when given the option.
5. The next screen asks if you want to customize any setting. Select No.
6. Finally set the name of the domain to seam_examples and leave the default domain location.
34.1.3. How to Start/Stop/Access your domain
Now that the server is installed and the domain is created you need to know how to start and stop
it, plus how to access its configuration console.
• Starting the domain:
This is the easy part - go to the $BEA_HOME/user_projects/domains/seam_examples/bin
directory and run the ./startWeblogic.sh script.
• Accessing the configuration console:
Launch http://127.0.0.1:7001/console in your web browser. It will ask for your username
and password that you entered before. We won't get into this much now, but this is the starting
point for a lot of the various configurations that are needed later.
• Stopping the domain:
There are a couple of options here:
• The recommended way is through the configuration console:
1. Select seam_examples on the left hand side of the console.
2. Choose the Control tab in the middle of the page.
3. Select the check box AdminServer in the table.
4. Choose Shutdown just above the table, and select either When work completes or Force
shutdown now as appropriate.
5. Then finally confirm that you want to shut this server down.
• Hitting Ctrl-C in the terminal where you started the domain.
No negative effects have been seen, but we would not recommend doing this while in the
middle of configuration changes in the console.
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•
A note on Weblogic classloading
When using the @DOMAIN/autodeploy directory as described in this chapter you
may see NoClassDefFound exceptions. If you see this try restarting the Weblogic
server. If you still see it remove the auto-deployed EAR/WAR files, restart the
server, and redeploy. We could not find a specific reason for this, but others
seem to be having this issue as well.
34.2. The jee5/booking Example
Do you want to run Seam using EJB's on Weblogic? If so there are some obstacles that you
will have to avoid. This section describes those obstacles and what changes are needed to the
jee5/booking example to get it deployed and functioning.
34.2.1. EJB3 Issues with Weblogic
For several releases of Weblogic there has been an issue with how Weblogic compiles EJB's
that use variable arguments in their methods. This is confirmed in the Weblogic 9.X and 10.X
versions. Seam uses variable arguments in one of its internal EJB's ( TimerServiceDispatcher
). So Seam will not function correctly without modifications.
The basic explanation of the issue is that the Weblogic EJB compiler believes that methods that
use varargs are transient and the deployment will fail with exceptions like below:
java.io.IOException: Compiler failed executable.exec:
/jboss/apps/bea/wlserver_10.0/user_projects/domains/seam_examples/servers/AdminServer
/cache/EJBCompilerCache/5yo5dk9ti3yo/org/jboss/seam/async/
TimerServiceDispatcher_qzt5w2_LocalTimerServiceDispatcherImpl.java:194: modifier transient
not allowed here
public transient javax.ejb.Timer scheduleAsynchronousEvent(java.lang.String arg0,
java.lang.Object[] arg1)
^
/jboss/apps/bea/wlserver_10.0/user_projects/domains/seam_examples/servers/AdminServer
/cache/EJBCompilerCache/5yo5dk9ti3yo/org/jboss/seam/async/
TimerServiceDispatcher_qzt5w2_LocalTimerServiceDispatcherImpl.java:275: modifier transient
not allowed here
public transient javax.ejb.Timer scheduleTimedEvent(java.lang.String arg0,
org.jboss.seam.async.TimerSchedule arg1, java.lang.Object[] arg2)
BEA has created a patch ( CR327275 ) for this issue that can be requested from their support. It
is rumored that it will be included in the final release of Weblogic 10.3, although not confirmed.
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Unfortunately a second issue has been reported and verified by BEA ( CR363182 ). This issue has
to do with certain EJB methods incorrectly left out of Weblogic's generated internal stub classes.
At the time of this writing the status of this issue is not known. When this issue has been patched,
and tested with Seam this reference guide chapter will be updated.
So that Seam's users can deploy an EJB application to Weblogic a special Weblogic specific
jar has been created, starting with Seam 2.0.2.CR2. It is located in the $SEAM/lib/interop
directory and is called jboss-seam-wls-compatible.jar . The only difference between this jar
and the jboss-seam.jar is that it does not contain the TimerServiceDispatcher EJB. To use
this jar simply rename the jboss-seam-wls-compatible.jar to jboss-seam.jar and replace
the original in your applications EAR file. The jee5/booking example demonstrates this.
34.2.2. Getting the jee5/booking Working
In this section we will go over the steps needed to get the jee5/booking example to up and
running.
34.2.2.1. Setting up the hsql datasource
This example uses the in memory hypersonic database, and the correct data source needs to be
set up. The admin console uses a wizard like set of pages to configure it.
1. Copy hsqldb.jar to the Weblogic domain's shared library directory:
cp ../../../lib/
hsqldb.jar /jboss/apps/bea/user_projects/domains/seam_examples/lib
2. Start up the server and navigate to the administration console following Section 34.1.3, “How
to Start/Stop/Access your domain”
3. On the left side tree navigate seam_examples - Services- JDBC - Data Sources.
4. You must lock the domain configuration using the button in the upper left box.
5. Then select the New button at the top of the data source table
6. Fill in the following:
a. Name: seam-jee5-ds
b. JNDI Name: seam-jee5-ds
c. Database Type and Driver: other
d. Select Next button
7. Select Next button on the Transaction Options page
8. Fill in the following on the Connection Properties page:
a. Database Name: hsqldb
b. Host Name: 127.0.0.1
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c. Port: 9001
d. Username: sa will empty password fields.
e. Select Next button
9. Fill in the following on the Connection Properties page:
a. Driver Class Name: org.hsqldb.jdbcDriver
b. URL: jdbc:hsqldb:.
c. Username: sa will empty password fields.
d. Leave the rest of the fields as is.
e. Select Next button
10.Choose the target domain for the data source in our case the only one AdminServer. Click Next.
11.Finally - apply the changes by selecting the Apply Changes button in the upper left corner.
34.2.2.2. Setting up Weblogics JSF Support
These are the instructions to deploy and configure Weblogic's JSF 1.2 libraries. Out of the box
Weblogic does not come with its own JSF libraries active, and unfortunately when deploying an
EAR based application Weblogic requires its own JSF libraries to function. This appears to be
caused by classloader issues. The assumption being that JSF libraries in the application are not
visible to Weblogic during deployment of the EAR application. Why this does not effect WAR based
applications is not known.
1. In the administration console navigate to the Deployments page using the left hand menu.
2. You must lock the domain configuration using the button in the upper left box.
3. Then select the Install button at the top of the deployments table
4. Using the directory browser navigate to the /jboss/apps/bea/wlserver_10.0/common/
deployable-libraries directory. Then select the jsj-1.2.war archive, and click the Next
button.
5. Make sure that the Install this deployment as a library is selected. Click the Next
button on the Install Application Assistant page.
6. Click the Next button on the Optional Settings page.
7. Make sure that the Yes, take me to the deployment's configuration screen. is selected.
Click the Finish button on the Review your choices and click Finish page.
8. On the Settings for jsf(1.2,1.2.3.1) page set the Deployment Order to 99 so that it is
deployed prior to autodeployed applications. Then click the Save button.
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9. Then activate the changes by clicking the green button in the upper left.
There is another step that is needed for this to work. For some reason, even with the steps above
classes in the jsf-api.jar are not found during application deployment. The only way I found
for this to work is to put the jsf-api.jar from $SEAM/lib directory in the domains shared library
/jboss/apps/bea/user_projects/domains/seam_domain/lib
1. Shutdown the server following Section 34.1.3, “How to Start/Stop/Access your domain”
2. Then execute
cp
../../../lib/jsf-api.jar
/jboss/apps/bea/user_projects/
domains/seam_examples/lib . Verify the jar was copied correctly.
3. Start up the server and navigate to the administration console following Section 34.1.3, “How
to Start/Stop/Access your domain”
4. Then verify a clean start up of the server.
34.2.2.3. Configuration and Build changes
OK - now we are ready to finally begin adjusting the seam application for deployment to the
Weblogic server.
resources/META-INF/persistence.xml
• Change the jta-data-source to what you entered above :
<jta-data-source>seam-jee5-ds</jta-data-source>
• Then comment out the glassfish properties.
• Then add these two properties for weblogic support.
<property name="hibernate.dialect"
value="org.hibernate.dialect.HSQLDialect"/>
<property name="hibernate.transaction.manager_lookup_class"
value="org.hibernate.transaction.WeblogicTransactionManagerLookup"/>
resources/META-INF/weblogic-application.xml
• This file needs to be created and should contain the following:
<?xml version="1.0" encoding="ISO-8859-1"?>
<weblogic-application>
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<library-ref>
<library-name>jsf</library-name>
<specification-version>1.2</specification-version>
<implementation-version>1.2</implementation-version>
<exact-match>false</exact-match>
</library-ref>
<prefer-application-packages>
<package-name>antlr.*</package-name>
</prefer-application-packages>
</weblogic-application>
• These changes do two two different things. The first element library-ref tells weblogic
that this application will be using the deployed JSF libraries. The second element preferapplication-packages tells weblogic that the antlr jars take precedence. This avoids
a conflict with hibernate.
resources/META-INF/ejb-jar.xml
• The changes described here work around an issue where Weblogic is only using a single
instance of the sessionBeanInterceptor for all session beans. Seam's interceptor caches
and stores some component specific attributes, so when a call comes in - the interceptor is
primed for a different component and an error is seen. To solve this problem you must define
a separate interceptor binding for each EJB you wish to use. When you do this Weblogic
will use a separate instance for each EJB.
Modify the assembly-descriptor element to look like this:
<assembly-descriptor>
<interceptor-binding>
<ejb-name>AuthenticatorAction</ejb-name>
<interceptor-class >org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
</interceptor-binding>
<interceptor-binding>
<ejb-name>BookingListAction</ejb-name>
<interceptor-class >org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
</interceptor-binding>
<interceptor-binding>
<ejb-name>RegisterAction</ejb-name>
<interceptor-class >org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
</interceptor-binding>
<interceptor-binding>
<ejb-name>ChangePasswordAction</ejb-name>
<interceptor-class >org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
</interceptor-binding>
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<interceptor-binding>
<ejb-name>HotelBookingAction</ejb-name>
<interceptor-class >org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
</interceptor-binding>
<interceptor-binding>
<ejb-name>HotelSearchingAction</ejb-name>
<interceptor-class >org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
</interceptor-binding>
<interceptor-binding>
<ejb-name>EjbSynchronizations</ejb-name>
<interceptor-class >org.jboss.seam.ejb.SeamInterceptor</interceptor-class>
</interceptor-binding>
</assembly-descriptor>
resources/WEB-INF/weblogic.xml
• This file needs to be created and should contain the following:
<?xml version="1.0" encoding="UTF-8"?>
<weblogic-web-app>
<library-ref>
<library-name>jsf</library-name>
<specification-version>1.2</specification-version>
<implementation-version>1.2</implementation-version>
<exact-match>false</exact-match>
</library-ref>
</weblogic-web-app>
• This file and the element library-ref tells Weblogic that this application will using
the deployed JSF libraries. This is needed in both this file and the
weblogicapplication.xml file because both applications require access.
resources/WEB-INF/web.xml
• Because the jsf-impl.jar is not going to be in the $WAR/WEB_INF/lib directory we need
to add a configuration listener to this file.
<listener>
<listener-class>com.sun.faces.config.ConfigureListener</listener-class>
</listener>
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34.2.2.4. Building and Deploying the Application
There are some changes needed to the build script and the jboss-seam.jar then we can deploy
the app.
build.xml
• Add the following to the build.xml . Note that richfaces-api.jar is only needed if using
the admin console to deploy. For some reason Weblogic needs it in the WAR when it scans
the application.
<fileset id="war.lib.extras" dir="${seam.dir}">
<include name="lib/richfaces-api.jar" />
</fileset>
• Next we need to add the follow so that the weblogic-application.xml will be packaged.
<!-- Resources to go in the ear -->
<fileset id="ear.resources" dir="${resources.dir}">
<include name="META-INF/application.xml" />
<include name="META-INF/weblogic-application.xml" />
<include name="META-INF/*-service.xml" />
<include name="META-INF/*-xmbean.xml" />
<include name="treecache.xml" />
<include name="*.jpdl.xml" />
<exclude name=".gpd.*" />
<include name="*.cfg.xml" />
<include name="*.xsd" />
</fileset>
• Then finally we need to add two jars to the EAR . Add these two lines to the ear.lib.extras
fileset.
<include name="examples/wiki/lib/jboss-archive-browsing.jar" />
<include name="lib/concurrent.jar" />
$SEAM/lib/interop/jboss-seam-wls-compatible.jar
• This is the change discussed above in Section 34.2.1, “EJB3 Issues with Weblogic” . There
are really two options.
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• Rename this jar and replace the original $SEAM/lib/jboss-seam.jar file. This approach
does not require any changes to the packaged EAR archive, but overwrites the original
jboss-seam.jar
• The other option is the modify the packaged EAR archive and replace the jboss-seam.jar
in the archive manually. This leaves the original jar alone, but requires a manual step when
ever the archive is packaged.
Assuming that you choose the first option for handling the jboss-seam-wls-compatible.jar
we can build the application by running ant archive at the base of the jee5/booking example
directory.
Because we chose to create our Weblogic domain in development mode we can deploy the
application by putting the EAR file in the domains autodeploy directory.
cp ./dist/jboss-seam-jee5.ear
/jboss/apps/bea/user_projects/domains/seam_examples/autodeploy
Check out the application at http://localhost:7001/seam-jee5/
34.3. The jpa booking example
This is the Hotel Booking example implemented in Seam POJO and Hibernate JPA and does
not require EJB3 support to run. The example already has a breakout of configurations and build
scripts for many of the common containers including Weblogic 10.X
First we'll build the example for Weblogic 10.x and do the needed steps to deploy. Then we'll talk
about what is different between the Weblogic versions, and with the JBoss AS version.
Note that this example assumes that Weblogic's JSF libraries have been configured as described
in Section 34.2.2.2, “Setting up Weblogics JSF Support”.
34.3.1. Building and deploying jpa booking example
Step one setup the datasource, step two build the app, step three deploy.
34.3.1.1. Setting up the datasource
The Weblogic 10.X version of the example will use the in memory hsql database instead of the built
in PointBase database. If you wish to use the PointBase database you must setup a PointBase
datasource, and adjust the hibernate setting in persistence.xml to use the PointBase dialect.
For reference the jpa/weblogic92 example uses PointBase.
Configuring the datasource is very similar to the jee5 Section 34.2.2.1, “Setting up the hsql
datasource” . Follow the steps in that section, but use the following entries where needed.
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• DataSource Name: seam-jpa-ds
• JNDI Name: seam-jpa-ds
34.3.1.2. Building the example
Building it only requires running the correct ant command:
ant -f build-weblogic10.xml
This will create a container specific distribution and exploded archive directories.
34.3.1.3. Deploying the example
When we installed Weblogic following Section 34.1.2, “Creating your Weblogic domain” we chose
to have the domain in development mode. This means to deploy the application all we need to
do is copy it into the autodeploy directory.
cp ./dist-weblogic10/jboss-seam-jpa.war
/jboss/apps/bea/user_projects/domains/seam_examples/autodeploy
Check out the application at the following http://localhost:7001/jboss-seam-jpa/ .
34.3.2. What's different with Weblogic 10.x
• Between the the Weblogic 10.x and 9.2 examples there are several differences:
• META-INF/persistence.xml — The 9.2 version is configured to use the PointBase
database and a pre-installed datasource. The 10.x version uses the hsql database and a
custom datasource.
• WEB-INF/weblogic.xml — This file and its contents solve an issue with an older version of
the ANTLR libraries that Weblogic 10.x uses internally. OC4J have the same issue as well. It
also configures the application to use the shared JSF libraries that were installed above.
<?xml version="1.0" encoding="UTF-8"?>
<weblogic-web-app
xmlns="http://www.bea.com/ns/weblogic/90"
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What's different with Weblogic 10.x
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://www.bea.com/ns/weblogic/90
http://www.bea.com/ns/weblogic/90/weblogic-web-app.xsd">
<library-ref>
<library-name>jsf</library-name>
<specification-version>1.2</specification-version>
<implementation-version>1.2</implementation-version>
<exact-match>false</exact-match>
</library-ref>
<container-descriptor>
<prefer-web-inf-classes>true</prefer-web-inf-classes>
</container-descriptor>
</weblogic-web-app>
This make Weblogic use classes and libraries in the web application before other libraries in
the classpath. Without this change hibernate is required to use a older, slower query factory
by setting the following property in the META-INF/persistence.xml file.
<property name="hibernate.query.factory_class"
value="org.hibernate.hql.classic.ClassicQueryTranslatorFactory"/>
• WEB-INF/components.xml — In the Weblogic 10.x version JPA entity transactions is enabled
by adding:
<transaction:entity-transaction entity-manager="#{em}"/>
• WEB-INF/web.xml — Because the jsf-impl.jar is not in the WAR this listener need to be
configured :
<listener>
<listener-class>com.sun.faces.config.ConfigureListener</listener-class>
</listener>
• Between the Weblogic 10.x version and the JBoss version there are more changes. Here is
the rundown:
• META-INF/persistence.xml — Except for datasource name the Weblogic version sets:
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<property name="hibernate.transaction.manager_lookup_class"
value="org.hibernate.transaction.WeblogicTransactionManagerLookup"/>
• WEB-INF/lib — The Weblogic version requires several library packages because they
are not included as they are with JBoss AS. These are primarily for hibernate, and its
dependencies.
• To use Hibernate as your JPA provider you need the following jars:
• hibernate.jar
• hibernate-annotations.jar
• hibernate-entitymanager.jar
• hibernate-validator.jar
• jboss-common-core.jar
• commons-logging.jar
• commons-collections.jar
• jboss-archive-browsing.jar
• Various third party jars that Weblogic needs:
• antlr.jar
• cglib.jar
• asm.jar
• dom4j.jar
• el-ri.jar
• javassist.jar
34.4. Deploying an application created using seam-gen on
Weblogic 10.x
seam-gen is a very useful tool for developers to quickly get an application up and running, and
provides a foundation to add your own functionality. Out of box seam-gen will produce applications
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Running seam-gen setup
configured to run on JBoss AS. These instructions will show the steps needed to get it to run on
Weblogic.
seam-gen was build for simplicity so, as you can imagine, deploying an application generated by
seam-gen to Weblogic 10.x is not too hard. Basically it consists of updating or removing some
configuration files, and adding dependent jars that Weblogic 10.x does not ship with.
This example will cover the basic seam-gen WAR deployment. This will demonstrate Seam
POJO components, Hibernate JPA, Facelets, Drools security, RichFaces, and a configurable
dataSource.
34.4.1. Running seam-gen setup
The first thing we need to do it tell seam-gen about the project we want to make. This is done by
running ./seam setup in the base directory of the Seam distribution. Note the paths here are my
own, feel free to change for you environment.
./seam setup
Buildfile: build.xml
init:
setup:
[echo] Welcome to seam-gen :-)
[input] Enter your Java project workspace (the directory that contains your
Seam projects) [C:/Projects] [C:/Projects]
/home/jbalunas/workspace
[input] Enter your JBoss home directory [C:/Program Files/jboss-4.2.2.GA]
[C:/Program Files/jboss-4.2.2.GA]
/jboss/apps/jboss-4.2.2.GA
[input] Enter the project name [myproject] [myproject]
weblogic-example
[echo] Accepted project name as: weblogic_example
[input] Select a RichFaces skin (not applicable if using ICEFaces) [blueSky]
([blueSky], classic, ruby, wine, deepMarine, emeraldTown, sakura, DEFAULT)
[input] Is this project deployed as an EAR (with EJB components) or a WAR
(with no EJB support) [ear] ([ear], war, )
war
[input] Enter the Java package name for your session beans [org.jboss.seam.
tutorial.weblogic.action] [org.jboss.seam.tutorial.weblogic.action]
org.jboss.seam.tutorial.weblogic.action
[input] Enter the Java package name for your entity beans [org.jboss.seam.
tutorial.weblogic.model] [org.jboss.seam.tutorial.weblogic.model]
org.jboss.seam.tutorial.weblogic.model
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[input] Enter the Java package name for your test cases [org.jboss.seam.
tutorial.weblogic.action.test] [org.jboss.seam.tutorial.weblogic.action.test]
org.jboss.seam.tutorial.weblogic.test
[input] What kind of database are you using? [hsql] ([hsql], mysql, oracle,
postgres, mssql, db2, sybase, enterprisedb, h2)
[input] Enter the Hibernate dialect for your database [org.hibernate.
dialect.HSQLDialect] [org.hibernate.dialect.HSQLDialect]
[input] Enter the filesystem path to the JDBC driver jar [lib/hsqldb.jar]
[lib/hsqldb.jar]
[input] Enter JDBC driver class for your database [org.hsqldb.jdbcDriver]
[org.hsqldb.jdbcDriver]
[input] Enter the JDBC URL for your database [jdbc:hsqldb:.] [jdbc:hsqldb:.]
[input] Enter database username [sa] [sa]
[input] Enter database password [] []
[input] Enter the database schema name (it is OK to leave this blank) [] []
[input] Enter the database catalog name (it is OK to leave this blank) [] []
[input] Are you working with tables that already exist in the database? [n]
(y, [n], )
[input] Do you want to drop and recreate the database tables and data in
import.sql each time you deploy? [n] (y, [n], )
[input] Enter your ICEfaces home directory (leave blank to omit ICEfaces) [] []
[propertyfile] Creating new property file:
/rhdev/projects/jboss-seam/cvs-head/jboss-seam/seam-gen/build.properties
[echo] Installing JDBC driver jar to JBoss server
[copy] Copying 1 file to /jboss/apps/jboss-4.2.2.GA/server/default/lib
[echo] Type 'seam create-project' to create the new project
BUILD SUCCESSFUL
Type ./seam
new-project to create your project and cd
weblogic_example to see the newly created project.
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/home/jbalunas/workspace/
What to change for Weblogic 10.X
34.4.2. What to change for Weblogic 10.X
First we change and delete some configuration files, then we update the libraries that are deployed
with the application.
34.4.2.1. Configuration file changes
build.xml
• Change the default target to archive.
<project name="weblogic_example" default="archive" basedir=".">
resources/META-INF/persistence-dev.xml
• Alter the jta-data-source to be seam-gen-ds (and use this as the jndi-name when
creating the data source in Weblogic's admin console)
• Change the transaction type to RESOURCE_LOCAL so that we can use JPA transactions.
<persistence-unit name="weblogic_example" transaction-type="RESOURCE_LOCAL">
• Add/modify the properties below for Weblogic support:
<property name="hibernate.cache.provider_class"
value="org.hibernate.cache.HashtableCacheProvider"/>
<property name="hibernate.transaction.manager_lookup_class"
value="org.hibernate.transaction.WeblogicTransactionManagerLookup"/>
• You'll need to alter persistence-prod.xml as well if you want to deploy to Weblogic using
the prod profile.
resource/WEB-INF/weblogic.xml
You will need to create this file and populate it following description of WEB-INF/weblogic.xml
[472].
resource/WEB-INF/components.xml
We want to use JPA transactions so we need to add the following to let Seam know.
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<transaction:entity-transaction entity-manager="#{entityManager}"/>
You will also need to add the transaction namespace and schema location to the top of the
document.
xmlns:transaction="http://jboss.com/products/seam/transaction"
http://jboss.com/products/seam/transaction
2.1.xsd
http://jboss.com/products/seam/transaction-
resource/WEB-INF/web.xml
WEB-INF/web.xml — Because the jsf-impl.jar is not in the WAR this listener need to be
configured :
<listener>
<listener-class>com.sun.faces.config.ConfigureListener</listener-class>
</listener>
resources/WEB-INF/jboss-app.xml
You can delete this file as we aren't deploying to JBoss AS ( jboss-app.xml is used to enable
classloading isolation in JBoss AS)
resources/*-ds.xml
You can delete these files as we aren't deploying to JBoss AS. These files define datasources
in JBoss AS, in Weblogic we will use the administration console.
34.4.2.2. Library changes
The seam-gen application has very similar library dependencies as the jpa example above. See
Section 34.3.2, “What's different with Weblogic 10.x”. Below is the changes that are needed to
get them in this application.
• Missing jar — There is one library that seam-gen does not provide by default. This needs to be
copied into your projects /lib directory manually.
• jboss-archive-browsing.jar — can be found in the @SEAM_DIST/examples/wiki/lib
directory.
• build.xml — Now we need to adjust the build.xml. Find the target war and add the following
to the end of the target.
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Building and Deploying your application
<copy todir="${war.dir}/WEB-INF/lib">
<fileset dir="${lib.dir}">
<!-- Misc 3rd party -->
<include name="commons-logging.jar" />
<include name="dom4j.jar" />
<include name="javassist.jar" />
<include name="cglib.jar" />
<include name="antlr.jar" />
<!-- Hibernate -->
<include name="hibernate.jar" />
<include name="hibernate-commons-annotations.jar" />
<include name="hibernate-annotations.jar" />
<include name="hibernate-entitymanager.jar" />
<include name="hibernate-validator.jar" />
<include name="jboss-archive-browsing.jar" />
</fileset>
</copy>
34.4.2.3. seam-gen development profile issue
There is currently an issue with the behavior of the seam-gen WAR application when built using the
development profile (the default) and deployed to Weblogic. The symptom is that the login page
of the application will always show a login failed message.
When the application is built using the development profile the action class files are placed in the
WEB-INF/dev directory. Normally these class files are hot deployable and managed by Seam. This
does not happen on Weblogic (see jira JBSEAM-2455 [http://jira.jboss.com/jira/browse/JBSEAM2455] for details and status).
To workaround this you need to modify the build-dev.properties file. Simply remove the
property action.dir=WEB-INF/dev.
34.4.3. Building and Deploying your application
Finally all that's left is deploying the application. This involves setting up a data source, building
the app, and deploying it.
34.4.3.1. Setting up the data source
Configuring the datasource is very similar to the jee5 Section 34.2.2.1, “Setting up the hsql
datasource”. Except for what is listed here follow that instruction from the link.
• DataSource Name: seam-gen-ds
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• JNDI Name: seam-gen-ds
34.4.3.2. Building the application
This is as easy as typing ant in the projects base directory.
34.4.3.3. Deploying the example
When we installed Weblogic following Section 34.1.2, “Creating your Weblogic domain” we chose
to have the domain in development mode. This means to deploy the application all we need to
do is copy it into the autodeploy directory.
cp
./dist/weblogic_example.war
autodeploy
/jboss/apps/bea/user_projects/domains/seam_examples/
Check out the application at the following http://localhost:7001/weblogic_example/. .
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Chapter 35.
Seam on IBM's Websphere
Websphere 6.1.x is IBM's application server offering. The latest release is 6.1.0.13 which does
not have EJB3 or JEE5 support. There is a recently released (Nov 07) EJB3 feature pack which
provides some support for EJB3 and JPA. Currently there is no true JEE5 offering from IBM. This
causes some issues with Seam integration with applications that use EJB3.
First we will go over some basic information about the Websphere environment that we used for
these examples. After a good deal of research and work we were able to get EJB3 applications to
function correctly. We will go over the details of those steps with the jee5 example. We will also
deploy the the JPA example application.
35.1. Websphere environment and deployment
information
Websphere is a commercial product and so we will not discuss the details of its installation other
than to say follow the directions provided by your particular installation type and license. This
section will detail the exact server versions used, installation tips, and some custom properties
that are needed for all of the examples.
35.1.1. Installation versions and tips
All of the examples and information in this chapter are based on the the latest version of
Websphere at the time of this writing.
• Websphere Application Server 6.1.0.13 [http://www.ibm.com/developerworks/websphere/
zones/was/]
• Feature Pack for EJB 3.0 for Websphere Application Server V6.1 (3.0.6.1.0.13) [http://www1.ibm.com/support/docview.wss?rs=180&uid=swg21287579]
The EJB3 feature pack that we installed came with the 6.1.0.13 patch version of Websphere.
Installing the feature pack does not ensure that your server will have the proper environment
for EJB3 applications. Be sure that as part of the installation of the feature pack you follow the
instructions to create a new server profile with the EJB3 feature pack enabled, or augment one of
your existing ones. This can also be done after the installation by running the profile managment
tool.
A note about restarting the server
There are times that restarting the server will be required after deploying or
changes the examples in this chapter. Its does not seem like every change requires
a restart. If you get errors or exceptions after modifing a property or deploying an
application try to restart the server.
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35.1.2. Required custom properties
There are a couple of Websphere custom properties that are required for Seam integration. These
properties are not needed specifically for Seam, but work around some issues with Websphere.
These are set following the instructions here : Setting web container custom properties [http://
www-1.ibm.com/support/docview.wss?rss=180&uid=swg21284395]
• prependSlashToResource = "true" — This solves a fairly common issue with Websphere
where applications are not using a leading "/" when attempting to access resources. If this is
not set then a java.net.MalformedURLException will be thrown. With this property set you
will still see warnings, but the resources will be retrieved as expected.
Detailed can be found at:
SRVE0238E: Resource paths must have a leading slash [http://www-1.ibm.com/
support/docview.wss?uid=swg21190234]
• com.ibm.ws.webcontainer.invokefilterscompatibility = "true" — This solves an
issue with Websphere where it throws a FileNotFoundException when a web application
attempts to access a file resource that does not actually exist on disk. This is a common practice
in modern web applications where filters or servlets are used to process resource requests like
these. This issue manifests itself as failures to retrieve JavaScript, CSS, images, etc... when
requesting a web page.
Detailed can be found at:
PK33090; 6.1: A filter that serves a file does not pop-up an alert message [http:/
/www-1.ibm.com/support/docview.wss?uid=swg24014758]
35.2. The jee5/booking example
The jee5/booking example is based on the Hotel Booking example (which runs on JBoss AS).
Out of the box it is designed to run on Glassfish, but with the steps below it can be deployed to
Websphere. It is located in the $SEAM_DIST/examples/jee5/booking directory.
As stated before the EJB3 feature pack does not provide a full jee5 implementation. This means
that there are some tricks to getting an application deployed and functioning.
35.2.1. Configuration file changes
Below are the configuration file changes that are need to the base example.
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Configuration file changes
resources/WEB-INF/components.xml
We need to change the way that we look up EJBs for Websphere. We need to remove the
/local from the end of the jndi-pattern attribute. It should look like this:
<core:init jndi-pattern="java:comp/env/jboss-seam-jee5/#{ejbName}" debug="true"/>
resources/WEB-INF/web.xml
This is the first place that we notice an unexpected change because this is not full jee5
implementation.
Websphere does not support Servlet 2.5, it requires Servlet 2.4. For this change we need
to adjust the top of the web.xml file to look like the following:
<xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
Next, we have to make some changes to the EJB references in the web.xml. These changes
are what will allow Websphere to bind the EJB2 references in the web module to the the actual
EJB3 beans in the EAR module. Replace all of the ejb-local-refs when the values below.
<!-- JEE5 EJB3 names -->
<ejb-local-ref>
<ejb-ref-name>jboss-seam-jee5/AuthenticatorAction</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local-home></local-home>
<local>org.jboss.seam.example.booking.Authenticator</local>
</ejb-local-ref>
<ejb-local-ref>
<ejb-ref-name>jboss-seam-jee5/BookingListAction</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local-home></local-home>
<local>org.jboss.seam.example.booking.BookingList</local>
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</ejb-local-ref>
<ejb-local-ref>
<ejb-ref-name>jboss-seam-jee5/RegisterAction</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local-home></local-home>
<local>org.jboss.seam.example.booking.Register</local>
</ejb-local-ref>
<ejb-local-ref>
<ejb-ref-name>jboss-seam-jee5/ChangePasswordAction</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local-home></local-home>
<local>org.jboss.seam.example.booking.ChangePassword</local>
</ejb-local-ref>
<ejb-local-ref>
<ejb-ref-name>jboss-seam-jee5/HotelBookingAction</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local-home></local-home>
<local>org.jboss.seam.example.booking.HotelBooking</local>
</ejb-local-ref>
<ejb-local-ref>
<ejb-ref-name>jboss-seam-jee5/HotelSearchingAction</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local-home></local-home>
<local>org.jboss.seam.example.booking.HotelSAll of the examples and informaearching</
local>
</ejb-local-ref>
<ejb-local-ref>
<ejb-ref-name>jboss-seam-jee5/EjbSynchronizations</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local-home></local-home>
<local>org.jboss.seam.transaction.LocalEjbSynchronizations</local>
</ejb-local-ref>
The important change is that there is an empty local-home element for each EJB. This tells
Websphere to make the correct bindings between the web module and the EJB3 beans. The
ejb-link element is simply not used.
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Note also that EjbSynchronizations is a built-in Seam EJB and not part of the Hotel Booking
example. This means that if your application's components.xml specifies transaction:ejbtransaction , then you must include:
<ejb-local-ref>
<ejb-ref-name>myapp/EjbSynchronizations</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local-home></local-home>
<local>org.jboss.seam.transaction.LocalEjbSynchronizations</local>
</ejb-local-ref>
in your web.xml. If you don't include it, you'll get the following error:
Name comp/env/myapp/EjbSynchronizations not found in context java:
resources/META-INF/persistence.xml
For this example we will be using the default datasource that comes with Websphere. To do
this change the jta-data-source element:
<jta-data-source>DefaultDatasource</jta-data-source>
Then we need to adjust some of the hibernate properties. First comment out the Glassfish
properties. Next you need to add/change the properties:
<!--<property name="hibernate.transaction.flush_before_completion" value="true"/>-->
<property name="hibernate.cache.provider_class"
value="org.hibernate.cache.HashtableCacheProvider"/>
<property name="hibernate.dialect" value="GlassfishDerbyDialect"/>
<property name="hibernate.transaction.manager_lookup_class"
value="org.hibernate.transaction.WebSphereExtendedJTATransactionLookup"/>
• hibernate.transaction.manager_lookup_class — Standard Hibernate transaction
manager property for Websphere 6.X
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• hibernate.transaction.flush_before_completion — This is commented out because
we want the container to manage the transactions. Also if this is set to true an exception
will be thrown by Websphere when the EJBContext is looked up.
com.ibm.wsspi.injectionengine.InjectionException:
EJBContext may only be looked up by or injected into an EJB
• hibernate.dialect — From WAS 6.1.0.9 on the embedded DB was switched to the same
Derby DB in Glassfish.
resources/GlassfishDerbyDialect.class
You will need to get the GlassfishDerbyDialect.class and copy it into the /resources
directory. The class exists in the JPA example and can be copied using the command below
assuming you are in jee5/booking directory:
cp ../../jpa/resources-websphere61/WEB-INF/classes/GlassfishDerbyDialect.class
./resources
This class will be put into the jboss-seam-jee5.jar file using changes to the build.xml
discussed later.
resources/import.sql
This file must also be copied from the JPA example because either the Derby DB or the dialect
does not support changes to the ID column. The files are identical except for the column
difference. Use the following command to make the copy
cp ../../jpa/resources-websphere61/import.sql ./resources
35.2.2. Building the jee5/booking example
In order to get the changes we have made into our application we need to make some changes to
the build.xml. There are also some additional jars that are required by our application in order
to work with Websphere. This section will cover what changes are needed to the build.xml.
35.2.2.1. New libraries dependencies
• JSF libraries — Websphere 6.1 comes with its own version of JSF 1.1 (Seam requires JSF 1.2).
So we must add these jars to our application:
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Building the jee5/booking example
• jsf-api.jar
• jsf-impl.jar
• Since Websphere is not a fully compliant JEE5 implementation we need to add these EL libraries:
• el-api.jar
• el-ri.jar
• jboss-seam.jar — for some reason when deploying the application through the Websphere
administration console it can not find the jboss-seam.jar at the base of the EAR archive. This
means that we need to add it to the /lib of the EAR.
• Finally we remove the log4j.jar so that all of the log output from our application will be added
to the Websphere log. Additional steps are required to fully configure log4j and those are outside
of the scope of this document.
35.2.2.2. Updating the build.xml file
Add the following entry to the bottom of the build.xml file. This overrides the default fileset
that is used to populate the jboss-seam-jee5.jar. The primary change is the addition of the
GlassfishDerbyDialect.class:
<fileset id="jar.resources" dir="${resources.dir}">
<include name="import.sql" />
<include name="seam.properties" />
<include name="GlassfishDerbyDialect.class" />
<include name="META-INF/persistence.xml" />
<include name="META-INF/ejb-jar.xml" />
</fileset>
Next we need to add the library dependencies discussed above. For this add the following to
bottom of the ear.lib.extras fileset entry:
<!--<include name="lib/log4j.jar" />-->
<include name="lib/el-api.jar" />
<include name="examples/jpa/lib/el-ri.jar" />
<include name="lib/jsf-api.jar" />
<include name="lib/jsf-impl.jar" />
<include name="lib/jboss-seam.jar" />
</fileset>
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Now all that is left is to execute the ant archive task and the built application will be in the
jee5/booking/dist directory.
35.2.3. Deploying the application to Websphere
So now we have everything we need in place. All that is left is to deploy it - just a few steps more.
For this we will use Websphere's administration console. As before there are some tricks and tips
that must be followed.
The steps below are for the Websphere version stated above, yours may be slightly different.
1. Log in to the administration console
https://localhost:9043/ibm/console
2. Access the Enterprise Application menu option under the Applications top menu.
3. At the top of the Enterprise Application table select Install. Below are installation wizard
pages and what needs to done on each:
• Preparing for the application installation
• Browse to the examples/jee5/booking/dist/jboss-seam-jee5.ear file using the file
upload widget.
• Select the Next button.
• Select installation options
• Select the Deploy enterprise beans check box. This is needed unless you used a
Websphere tool to package the application.
• Select the Next button.
• Map modules to servers
• No changes needed here as we only have one server. Select the Next button.
• Map EJB references to beans This page will list all of the beans that we entered in the
web.xml.
• Make sure that Allow EJB reference targets to resolve automatically check
box is selected. This will tell Websphere to bind our EJB3 beans to the EJB references
in the web module.
• Select the Next button.
• Map virtual hosts for Web modules
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• No changes needed here. Select the Next button.
• Summary
• No changes needed here. Select the Finish button.
• Installation
• Now you will see it installing and deploying your application.
• When if finishes select the Save link and you will be returned to the Enterprise
Applications table.
4. Now that we have our application installed we need to make some adjustments to it before
we can start it:
• Starting from the Enterprise Applications table select the Seam Booking link.
• Select the Manage Modules link.
• Select the jboss-seam-jee5.war link.
• Change the Class loader order combo box to Classes loaded with application
class loader first.
• Select Apply and then Save options.
• Return the Seam Booking page.
• On this page select the Class loading and update detection link.
• Select the radio button for Classes loaded with application class loader first.
• Even though we are not enabling class reload you must also enter a valid number in the
Polling interval for updated files text area (zero works fine).
• Select Apply and then Save options.
• You should verify that the change you just made has been remembered. We have had
problems with the last class loader change not taking effect - even after a restart. If the
change did not take you will need to do it manually, following these directions:
• Open the following file in a text editor of your choice:
$WebSphereInstall/$yourServerName/profiles/$yourProfileName/config/cells/
$yourCellName/applications/Seam Booking.ear/deployments/
Seam Booking/deployment.xml
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• Modify the following line so that PARENT_FIRST is now PARENT_LAST:
<classloader xmi:id="Classloader_#######" mode="PARENT_FIRST"/>
• Save the file and now when go to the Class loading and update detection page you
should see Classes loaded with application class loader first selected.
5. To start the application return to the Enterprise Applications table and select our application
in the list. Then choose the Start button at the top of the table.
6. You can now access the application at http://localhost:9080/seam-jee5/ .
A note about Websphere Stateful bean timeouts
The default timeout period for a Websphere 6.1 Stateful EJB is 10 minutes. This
means that you may see some EJB timeout exceptions after some idle time. It is
possible to adjust the timeout of the Stateful EJBs on an individual basis, but that is
beyond the scope of this document. See the Websphere documentation for details.
35.3. The jpa booking example
Thankfully getting the jpa example to work is much easier than the jee5 example. This is the Hotel
Booking example implemented in Seam POJOs and using Hibernate JPA with JPA transactions.
It does not require EJB3 support to run.
The example already has a breakout of configurations and build scripts for many of the common
containers including Websphere.
First thing we are going to do is build and deploy that example. Then we'll go over some key
changes that we needed.
35.3.1. Building the jpa example
Building it only requires running the correct ant command:
ant websphere61
This will create container specific distribution and exploded archive directories with the
websphere61 label.
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35.3.2. Deploying the jpa example
This is similar to the jee5 example at Section 35.2.3, “Deploying the application to Websphere”,
but without so many steps.
• From the Enterprise Applications table select the Install button.
• Preparing for the application installation
• Browse to the examples/jpa/dist-websphere61/jboss-seam-jpa.war file using the file
upload widget.
• In the Context root text box enter jboss-seam-jpa.
• Select the Next button.
• Select the Next button for the next three pages, no changes are needed.
• Summary page
• Review the settings if you wish and select the Finish button to install the application.
When installation finished select the Save link and you will be returned to the Enterprise
Applications table.
• As with the jee5 example there are some class loader changes needed before we start the
application. Follow the instructions at installation adjustments for jee5 example but exchange
jboss-seam-jpa for Seam Booking.
• Finally start the application by selecting it in the Enterprise Applications table and clicking
the Start button.
• You can now access the application at the http://localhost:9080/jboss-seam-jpa/
index.html.
35.3.3. Whats different for Websphere 6.1
The differences between the JPA examples that deploys to JBoss 4.2 and Websphere 6.1 are
mostly expected; library and configuration file changes.
• Configuration file changes
• WEB-INF/web.xml — the only significant change is that Websphere 6.1 only support Servlet
2.4 so the top of this file was changed.
• META-INF/persistence.xml — the main changes here are for the datasource JNDI path,
switching to the Websphere 6.1 transaction manager look up class, and changing the
hibernate dialect to be GlassfishDerbyDialect .
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• WEB-INF/classes/GlassfishDerbyDialect.class
hibernate dialect change to GlassfishDerbyDialect
— this class is needed for the
• import.sql — either for the dialect or Derby DB the ID column can not be populated by this
file and was removed.
• Changes for dependent libraries
WEB-INF/lib — The Websphere version requires several library packages because they are
not included as they are with JBoss AS. These are primarily for hibernate, JSF-RI support and
their dependencies. Below are listed only the additional jars needed above and beyond the
JBoss JPA example.
• To use Hibernate as your JPA provider you need the following jars:
• hibernate.jar
• hibernate-annotations.jar
• hibernate-commons-annotations.jar
• hibernate-entitymanager.jar
• hibernate-validator.jar
• commons-collections.jar
• jboss-archive-browsing.jar
• Seam requires JSF 1.2 and these are the jars needed for that. Websphere 6.1 ships with its
own implementation of JSF 1.1.
• jsf-api.jar
• jsf-impl.jar
• el-ri.jar
• el-api.jar
• Various third party jars that Websphere needs:
• antlr.jar
• cglib.jar
• asm.jar
• dom4j.jar
• javassist.jar
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35.4. Deploying an application created using seam-gen on
Websphere 6.1.0.13
seam-gen is a very useful tool for developers to quickly get an application up and running, and
provides a foundation to add your own functionality. Out of box seam-gen will produce applications
configured to run on JBoss AS. These instructions will show the steps needed to get it to run
on Websphere. As stated above in Section 35.2, “ The jee5/booking example ” there are some
tricky changes needed to get an EJB3 application running. This section will take you through the
exact steps.
35.4.1. Running seam-gen Setup
The first step is setting up seam-gen to construct the base project. There are several choices
made below, specifically the datasource and hibernate values that we will adjust once the project
is created.
./seam setup
Buildfile: build.xml
init:
setup:
[echo] Welcome to seam-gen :-)
[input] Enter your Java project workspace (the directory that contains your
Seam projects) [C:/Projects] [C:/Projects]
/home/jbalunas/workspace
[input] Enter your JBoss home directory [C:/Program Files/jboss-4.2.2.GA]
[C:/Program Files/jboss-4.2.2.GA]
/home/jbalunas/jboss/jboss-4.2.2.GA
[input] Enter the project name [myproject] [myproject]
websphere_example
[echo] Accepted project name as: websphere_example
[input] Do you want to use ICEFaces instead of RichFaces [n] (y, [n], )
[input] skipping input as property icefaces.home.new has already been set.
[input] Select a RichFaces skin [blueSky] ([blueSky], classic, ruby, wine,
deepMarine, emeraldTown, sakura, DEFAULT)
[input] Is this project deployed as an EAR (with EJB components) or a WAR
(with no EJB support) [ear] ([ear], war, )
[input] Enter the Java package name for your session beans [org.jboss.seam.
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tutorial.websphere.action] [org.jboss.seam.tutorial.websphere.action]
org.jboss.seam.tutorial.websphere.action
[input] Enter the Java package name for your entity beans [org.jboss.seam.
tutorial.websphere.model] [org.jboss.seam.tutorial.websphere.model]
org.jboss.seam.tutorial.websphere.model
[input] Enter the Java package name for your test cases [org.jboss.seam.
tutorial.websphere.action.test] [org.jboss.seam.tutorial.websphere.action.test]
org.jboss.seam.tutorial.websphere.test
[input] What kind of database are you using? [hsql] ([hsql], mysql, oracle,
postgres, mssql, db2, sybase, enterprisedb, h2)
[input] Enter the Hibernate dialect for your database [org.hibernate.
dialect.HSQLDialect] [org.hibernate.dialect.HSQLDialect]
[input] Enter the filesystem path to the JDBC driver jar [lib/hsqldb.jar]
[lib/hsqldb.jar]
[input] Enter JDBC driver class for your database [org.hsqldb.jdbcDriver]
[org.hsqldb.jdbcDriver]
[input] Enter the JDBC URL for your database [jdbc:hsqldb:.]
[jdbc:hsqldb:.]
[input] Enter database username [sa] [sa]
[input] Enter database password [] []
[input] Enter the database schema name (it is OK to leave this blank) [] []
[input] Enter the database catalog name (it is OK to leave this blank) [] []
[input] Are you working with tables that already exist in the database? [n]
(y, [n], )
[input] Do you want to drop and recreate the database tables and data in
import.sql each time you deploy? [n] (y, [n], )
[propertyfile] Creating new property file:
/rhdev/projects/jboss-seam/svn-seam_2_0/jboss-seam-2_0/seam-gen/build.properties
[echo] Installing JDBC driver jar to JBoss server
[copy] Copying 1 file to /home/jbalunas/jboss/jboss-4.2.2.GA/server/default/lib
[echo] Type 'seam create-project' to create the new project
BUILD SUCCESSFUL
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Changes needed for deployment to Websphere
Total time: 3 minutes 5 seconds
Type ./seam
new-project to create your project and cd
/home/jbalunas/workspace/
websphere_example to the newly created structure.
35.4.2. Changes needed for deployment to Websphere
We now need to make some changes to the generated project.
35.4.2.1. Configuration file changes
resources/META-INF/persistence-dev.xml
• Alter the jta-data-source to be DefaultDatasource. We are going to be using the
integrated Websphere DB.
• Add or change the properties below. These are described in detail at Section 35.2, “ The
jee5/booking example ”:
<property name="hibernate.dialect" value="GlassfishDerbyDialect"/>
<property name="hibernate.hbm2ddl.auto" value="update"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.format_sql" value="true"/>
<property name="hibernate.cache.provider_class"
value="org.hibernate.cache.HashtableCacheProvider"/>
<property name="hibernate.transaction.manager_lookup_class"
value="org.hibernate.transaction.WebSphereExtendedJTATransactionLookup"/>
• Remove the JBoss AS specific method of exposing the EntityManagerFactory:
<property
name="jboss.entity.manager.factory.jndi.name"
value="java:/websphere_exampleEntityManagerFactory">
• You'll need to alter persistence-prod.xml as well if you want to deploy to Websphere
using the prod profile.
resources/GlassfishDerbyDialect.class
As with other examples we need to include this class for DB support. It can be copied from
the jpa example into the websphere_example/resources directory.
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cp
$SEAM/examples/jpa/resources-websphere61/WEB-INF/classes/
GlassfishDerbyDialect.class
./resources
resources/META-INF/jboss-app.xml
You can delete this file as we aren't deploying to JBoss AS ( jboss-app.xml is used to enable
classloading isolation in JBoss AS)
resources/*-ds.xml
You can delete these file as we aren't deploying to JBoss AS (these files define datasources
in JBoss AS, we are using Websphere's default datasource)
resources/WEB-INF/components.xml
• Enable container managed transaction integration - add the
<transaction:ejbtransaction
/>
component,
and
it's
namespace
declaration
xmlns:transaction="http://jboss.com/products/seam/transaction"
• Alter the jndi-pattern to java:comp/env/websphere_example/#{ejbName}
• We do not need managed-persistence-context for this example and so can delete its
entry.
<persistence:managed-persistence-context name="entityManager"
auto-create="true"
persistence-unit-jndi-name="java:/websphere_exampleEntityManagerFactory"/>
resources/WEB-INF/web.xml
Websphere does not support Servlet 2.5, it required Servlet 2.4. For this change we
need to adjust the top of the web.xml file to look like the following:
<?xml version="1.0" encoding="UTF-8"?>
<web-app version="2.4"
xmlns="http://java.sun.com/xml/ns/j2ee"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee
http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
As with the jee5/booking example we need to add EJB references to the web.xml. These
references require the empty local-home to flag them for Websphere to perform the proper
binding.
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Changes needed for deployment to Websphere
<ejb-local-ref>
<ejb-ref-name>websphere_example/AuthenticatorAction</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local-home></local-home>
<local>org.jboss.seam.tutorial.websphere.action.Authenticator</local>
</ejb-local-ref>
<ejb-local-ref>
<ejb-ref-name>websphere_example/EjbSynchronizations</ejb-ref-name>
<ejb-ref-type>Session</ejb-ref-type>
<local-home></local-home>
<local>org.jboss.seam.transaction.LocalEjbSynchronizations</local>
</ejb-local-ref>
35.4.2.2. Creating the AuthenticatorAction EJB
We want to take the existing Authenticator Seam POJO component and create an EJB3 out of it.
1. • Rename the class to AuthenticatorAction
• Add the @Stateless annotation to the new AuthenticatorAction class.
• Create an interface called Authenticator which AuthenticatorAction implements (EJB3
requires session beans to have a local interface). Annotate the interface with @Local , and
add a single method with same signature as the authenticate in AuthenticatorAction .
@Name("authenticator") @Stateless public class
AuthenticatorAction implements Authenticator {
@Local public interface Authenticator {
public boolean authenticate();
}
2. We've already added its reference to the web.xml file so are good to go.
35.4.2.3. Extra jar dependencies and other changes to the build.xml
This application has similar requirements as the jee5/booking example.
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• Change the default target to archive (we aren't going to cover automatic deployment to
Websphere).
<project name="websphere_example" default="archive" basedir=".">
• Websphere looks for the drools /security.drl file in the root of the war file instead of the
root of the websphere_example.jar so we need to have the build.xml move it to the correct
location at build time. The following must be added at the top of the <target name="war"
depends="compile" description="Build the distribution .war file"> target.
<copy todir="${war.dir}">
<fileset dir="${basedir}/resources" >
<include name="*.drl" />
</fileset>
</copy>
• We need to ge the GlassfishDerbyDialect.class into our application jar. To do that find the
jar task and modify the top of it so that it looks like this:
<target name="jar" depends="compile,copyclasses"
description="Build the distribution .jar file">
<copy todir="${jar.dir}">
<fileset dir="${basedir}/resources">
<include name="seam.properties" />
<include name="*.drl" />
<include name="GlassfishDerbyDialect.class" />
</fileset>
</copy>
...
• Next we need to get the jboss-seam.jar into the base of the EAR file. For deployment
Websphere requires this jar to be in both the /lib directory and at the base of the EAR. You
must add the following to the archive task:
<fileset dir="${lib.dir}">
<include name="jboss-seam.jar" />
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Changes needed for deployment to Websphere
</fileset>
So that the whole archive task looks like:
<target name="archive" depends="jar,war,ear"
description="Package the archives">
<jar jarfile="${dist.dir}/${project.name}.jar" basedir="${jar.dir}"/>
<jar jarfile="${dist.dir}/${project.name}.war" basedir="${war.dir}"/>
<jar jarfile="${dist.dir}/${project.name}.ear">
<fileset dir="${ear.dir}"/>
<fileset dir="${dist.dir}">
<include name="${project.name}.jar"/>
<include name="${project.name}.war"/>
</fileset>
<fileset dir="${lib.dir}">
<include name="jboss-seam.jar" />
</fileset>
</jar>
</target>
• Now we need to get extra jars into the build.xml. Look for the <fileset dir="${basedir}">
section of the task below. Add the new includes at the bottom of the fileset.
<target name="ear" description="Build the EAR">
<copy todir="${ear.dir}">
<fileset dir="${basedir}/resources">
<include name="*jpdl.xml" />
<include name="*hibernate.cfg.xml" />
<include name="jbpm.cfg.xml" />
</fileset>
<fileset dir="${lib.dir}">
<include name="jboss-seam.jar" />
</fileset>
<fileset dir="${basedir}">
<include name="lib/jbpm*.jar" />
<include name="lib/jboss-el.jar" />
<include name="lib/drools-*.jar"/>
<include name="lib/core.jar"/>
<include name="lib/janino*.jar"/>
<include name="lib/antlr-*.jar"/>
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<include name="lib/mvel*.jar"/>
<include name="lib/richfaces-api*.jar" />
</fileset>
</copy>
<copy todir="${ear.dir}/META-INF">
<fileset dir="${basedir}/resources/META-INF">
<include name="application.xml" />
<include name="jboss-app.xml" />
</fileset>
</copy>
</target>
• Hibernate dependencies
<!-- Hibernate and deps -->
<include name="lib/hibernate.jar"/>
<include name="lib/hibernate-commons-annotations.jar"/>
<include name="lib/hibernate-annotations.jar"/>
<include name="lib/hibernate-entitymanager.jar"/>
<include name="lib/hibernate-validator.jar"/>
<include name="lib/jboss-common-core.jar" />
• JSF dependencies. You will need to copy the el-ri.jar from the $SEAM/examples/jpa/lib
directory.
<!-- jsf libs -->
<include name="lib/jsf-api.jar" />
<include name="lib/jsf-impl.jar" />
<include name="lib/el-api.jar" />
<include name="lib/el-ri.jar"/>
• Third party dependencies. You will need to copy the jboss-archive-browsing.jar from the
$SEAM/examples/jpa/lib directory into the the projects /lib directory. You will also need
to acquire the concurrent.jar and place it in the same directory. You can get this from any
jboss distribution or just search for it.
<!-- 3rd party and supporting jars -->
<!--<include name="lib/log4j.jar" />-->
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Changes needed for deployment to Websphere
<include name="lib/javassist.jar"/>
<include name="lib/dom4j.jar" />
<include name="lib/jboss-archive-browsing.jar" />
<include name="lib/concurrent.jar" />
<include name="lib/cglib.jar"/>
<include name="lib/asm.jar"/>
<include name="lib/antlr.jar" />
<include name="lib/commons-logging.jar" />
<include name="lib/commons-collections.jar" />
• jboss-seam.jar - this is needed in both the ear base and /lib directory.
<!-- seam jar -->
<include name="lib/jboss-seam.jar" />
You should end up with something like:
<fileset dir="${basedir}">
<include name="lib/jbpm*.jar" />
<include name="lib/jboss-el.jar" />
<include name="lib/drools-*.jar"/>
<include name="lib/core.jar"/>
<include name="lib/janino*.jar"/>
<include name="lib/antlr-*.jar"/>
<include name="lib/mvel*.jar"/>
<include name="lib/richfaces-api*.jar" />
<!-- Hibernate and deps -->
<include name="lib/hibernate.jar"/>
<include name="lib/hibernate-commons-annotations.jar"/>
<include name="lib/hibernate-annotations.jar"/>
<include name="lib/hibernate-entitymanager.jar"/>
<include name="lib/hibernate-validator.jar"/>
<include name="lib/jboss-common-core.jar" />
<!-- jsf libs -->
<include name="lib/jsf-api.jar" />
<include name="lib/jsf-impl.jar" />
<include name="lib/el-api.jar" />
<include name="lib/el-ri.jar"/>
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<!-- 3rd party and supporting jars -->
<!--<include name="lib/log4j.jar" />-->
<include name="lib/javassist.jar"/>
<include name="lib/dom4j.jar" />
<include name="lib/jboss-archive-browsing.jar" />
<include name="lib/concurrent.jar" />
<include name="lib/cglib.jar"/>
<include name="lib/asm.jar"/>
<include name="lib/antlr.jar" />
<include name="lib/commons-logging.jar" />
<include name="lib/commons-collections.jar" />
<!-- seam jar -->
<include name="lib/jboss-seam.jar" />
</fileset>
35.4.2.4. Building and deploying the seam-gen'd application to
Websphere
• Build your application by calling ant in the base directory of your project (ex. /
home/jbalunas/workspace/websphere_example ). The target of the build will be dist/
websphere_example.ear .
• To deploy the application follow the instructions here : Section 35.2.3, “Deploying the application
to Websphere” but use references to this project websphere_example instead of jboss-seamjee5.
• Checkout the app at: http://localhost:9080/websphere_example/index.html
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Chapter 36.
Dependencies
36.1. Project Dependencies
This section both lists the compile-time and runtime dependencies for Seam. Where the type
is listed as ear, the library should be included in the /lib directory of your application's ear file.
Where the type is listed as war, the library should be placed in the /WEB-INF/lib directory of your
application's war file. The scope of the dependency is either all, runtime or provided (by JBoss
AS 4.2).
Up to date version information and complete dependency information is not included in the docs,
but is provided in the /dependency-report.txt which is generated from the Maven POMs stored
in /build. You can generate this file by running ant dependencyReport.
36.1.1. Core
Table 36.1.
Name
Scope
Type
Notes
all
ear
The core Seam library, always
required.
jboss-seam-debug.jar
runtime
war
Include during development
when enabling Seam's debug
feature
jboss-seam-ioc.jar
runtime
war
Required when using Seam with
Spring
jboss-seam-pdf.jar
runtime
war
Required when using Seam's
PDF features
jboss-seam-
runtime
war
Required when using Seam
Remoting
jboss-seam-ui.jar
runtime
war
Required to use the Seam JSF
controls
jsf-api.jar
provided
JSF API
jsf-impl.jar
provided
JSF Reference Implementation
jsf-facelets.jar
runtime
war
Facelets
urlrewrite.jar
runtime
war
URL Rewrite library
quartz.jar
runtime
ear
Required when you wish
to use Quartz with Seam's
asynchronous features
jboss-seam.jar
remoting.jar
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Chapter 36. Dependencies
36.1.2. RichFaces
Table 36.2. RichFaces dependencies
Name
richfaces-api.jar
Scope
Type
Notes
all
ear
Required to use RichFaces.
Provides API classes that you
may wish to use from your
application e.g. to create a tree
richfaces-impl.jar
runtime
war
Required to use RichFaces.
richfaces-ui.jar
runtime
war
Required to use RichFaces.
Provides all the UI components.
Scope
Type
Notes
activation.jar
runtime
ear
Required for attachment support
mail.jar
runtime
ear
Required
support
for
outgoing
mail
mail-ra.jar
compile
only
Required
support
for
incoming
mail
36.1.3. Seam Mail
Table 36.3. Seam Mail Dependencies
Name
mail-ra.rar should be deployed to
the application server at runtime
jboss-seam-mail.jar
runtime
war
Seam Mail
36.1.4. Seam PDF
Table 36.4. Seam PDF Dependencies
Name
Type
Scope
Notes
itext.jar
runtime
war
PDF Library
jfreechart.jar
runtime
war
Charting library
jcommon.jar
runtime
war
Required by JFreeChart
jboss-seam-pdf.jar
runtime
war
Seam PDF core library
36.1.5. JBoss Rules
The JBoss Rules libraries can be found in the drools/lib directory in Seam.
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JBPM
Table 36.5. JBoss Rules Dependencies
Name
Scope
Type
Notes
antlr-runtime.jar
runtime
ear
ANTLR Runtime Library
core.jar
runtime
ear
Eclipse JDT
drools-compiler.jar
runtime
ear
drools-core.jar
runtime
ear
janino.jar
runtime
ear
mvel.jar
runtime
ear
36.1.6. JBPM
Table 36.6. JBPM dependencies
Name
Scope
Type
jbpm-jpdl.jar
runtime
ear
Notes
36.1.7. GWT
These libraries are required if you with to use the Google Web Toolkit (GWT) with your Seam
application.
Table 36.7. GWT dependencies
Name
gwt-servlet.jar
Scope
Type
runtime
war
Notes
The GWT Servlet libs
36.1.8. Spring
These libraries are required if you with to use the Spring Framework with your Seam application.
Table 36.8. Spring Framework dependencies
Name
spring.jar
Scope
Type
runtime
ear
Notes
The Spring Framework library
36.1.9. Groovy
These libraries are required if you with to use Groovy with your Seam application.
Table 36.9. Groovy dependencies
Name
groovy-all.jar
Scope
Type
runtime
ear
Notes
The Groovy libs
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Chapter 36. Dependencies
36.2. Dependency Management using Maven
Maven offers support for transitive dependency management and can be used to manage the
dependencies of your Seam project. You can use Maven Ant Tasks to integrate Maven into your
Ant build, or can use Maven to build and deploy your project.
We aren't actually going to discuss how to use Maven here, but just run over some basic POMs
you could use.
Released versions of Seam are available in http://repository.jboss.org/maven2 and nightly
snapshots are available in http://snapshots.jboss.org/maven2.
All the Seam artifacts are available in Maven:
<dependency>
<groupId>org.jboss.seam</groupId>
<artifactId>jboss-seam</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.seam</groupId>
<artifactId>jboss-seam-ui</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.seam</groupId>
<artifactId>jboss-seam-pdf</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.seam</groupId>
<artifactId>jboss-seam-remoting</artifactId>
</dependency>
<dependency>
<groupId>org.jboss.seam</groupId>
<artifactId>jboss-seam-ioc</artifactId>
</dependency>
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Dependency Management using Maven
<dependency>
<groupId>org.jboss.seam</groupId>
<artifactId>jboss-seam-ioc</artifactId>
</dependency>
This sample POM will give you Seam, JPA (provided by Hibernate) and Hibernate Validator:
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/mavenv4_0_0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>org.jboss.seam.example/groupId>
<artifactId>my-project</artifactId>
<version>1.0</version>
<name>My Seam Project</name>
<packaging>jar</packaging>
<repositories>
<repository>
<id>repository.jboss.org</id>
<name>JBoss Repository</name>
<url>http://repository.jboss.org/maven2</url>
</repository>
</repositories>
<dependencies>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>3.0.0.GA</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-annotations</artifactId>
<version>3.3.0.ga</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
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Chapter 36. Dependencies
<artifactId>hibernate-entitymanager</artifactId>
<version>3.3.1.ga</version>
</dependency>
<dependency>
<groupId>org.jboss.seam</groupId>
<artifactId>jboss-seam</artifactId>
<version>2.0.0.GA</version>
</dependency>
</dependencies>
</project>
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