Accessing databases from WebSphere

Accessing databases from WebSphere
Chapter 9 of WebSphere Application
Server V7 Administration and
Configuration Guide, SG24-7615
WebSphere Application Server V7:
Accessing Databases from WebSphere
When an application or WebSphere® component requires access to a database,
that database must be defined to WebSphere as a data source. Two basic
definitions are required:
򐂰 A JDBC provider definition defines an existing database provider, including
the type of database access that it provides and the location of the database
vendor code that provides the implementation.
򐂰 A data source definition defines which JDBC provider to use, the name and
location of the database, and other connection properties.
In this chapter, we discuss the various considerations for accessing databases
from WebSphere.
We cover the following topics:
򐂰
򐂰
򐂰
򐂰
򐂰
򐂰
򐂰
“JDBC resources” on page 2
“Steps in defining access to a database” on page 7
“Example: Connecting to an IBM DB2 database” on page 9
“Example: Connecting to an Oracle database” on page 17
“Example: Connecting to an SQL Server database” on page 24
“Example: Connecting to an Informix Dynamic Server database” on page 30
“Configuring connection pooling properties” on page 36
© Copyright IBM Corp. 2009-2010. All rights reserved.
1
JDBC resources
The JDBC API provides a programming interface for data access of relational
databases from the Java™ programming language. WebSphere Application
Server V7 supports the following JDBC APIs:
򐂰 JDBC 4.0 (New in V7)
򐂰 JDBC 3.0
򐂰 JDBC 2.1 and Optional Package API (2.0)
In the following sections, we explain how to create and configure data source
objects for use by JDBC applications. This method is the recommended method
to connect to a database and the only method if you intend to use connection
pooling and distributed transactions.
Note: DB2® for z/OS® local JDBC Provider (RRS) Version 6.1 is not
supported in WebSphere Application Server V7.0. If you use this provider, you
need to migrate IBM® JCC Driver or DB2 Universal JDBC Driver.
The following database platforms are supported for JDBC:
򐂰
򐂰
򐂰
򐂰
򐂰
򐂰
򐂰
DB2
Oracle
Sybase
Informix®
SQL Server
IBM Cloudscape and IBM Derby (test and development only)
Third-party vendor JDBC data source using SQL99 standards
JDBC providers and data sources
A data source represents a real-world data source, such as a relational database.
When a data source object is registered with a JNDI naming service, an
application can retrieve it from the naming service and use it to make a
connection to the data source that it represents.
Information about the data source and how to locate it, such as its name, the
server on which it resides, its port number, and so on, is stored in the form of
properties on the DataSource object. Storing this information in this manner
makes an application more portable because it does not need to hard code a
driver name, which often includes the name of a particular vendor. It also makes
maintaining the code easier because if, for example, the data source is moved to
a different server, all that needs to be done is to update the relevant property in
the data source. None of the code using that data source needs to be touched.
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WebSphere Application Server V7: Accessing Databases
After a data source is registered with an application server’s JNDI name space,
application programmers can use it to make a connection to the data source that
it represents.
The connection usually is a pooled connection. In other words, when the
application closes the connection, the connection is returned to a connection
pool, rather than being destroyed.
Data source classes and JDBC drivers are implemented by the data source
vendor. By configuring a JDBC provider, you provide information about the set of
classes that are used to implement the data source and the database driver.
Also, you provide the environment settings for the DataSource object. A driver
can be written purely in the Java programming language or in a mixture of the
Java programming language and the Java Native Interface (JNI) native methods.
In the next sections, we describe how to create and configure data source
objects, as well as how to configure the connection pools used to serve
connections from the data source.
WebSphere support for data sources
The programming model for accessing a data source is as follows:
1. An application retrieves a DataSource object from the JNDI naming space.
2. After the DataSource object is obtained, the application code calls the
getConnection() request on the data source to get a Connection object. The
connection is obtained from a pool of connections.
3. After the connection is acquired, the application sends SQL queries or
updates to the database.
In addition to the data source support for Java EE 5, J2EE 1.3, and J2EE 1.4
applications, support is also provided for J2EE 1.2 data sources. The two types
of support differ in how connections are handled. However, from an application
point of view, they look the same.
WebSphere Application Server V7: Accessing Databases from WebSphere
3
Data source support
The primary data source support is intended for J2EE 1.3 and J2EE 1.4, and
Java EE 5 applications. Connection pooling is provided by two components, a
JCA Connection Manager, and a relational resource adapter. See Figure 1.
Application Server
Resource
Adapter
Datasource
JCA
Connection
Manager
DB Connection
Pool
DB Server
Conne
ctions
Delegate
JDBC Driver
Application
Connection
Factory
Figure 1 Resource adapter in J2EE connector architecture
The JCA Connection Manager provides connection pooling, local transactions,
and security support.
The relational resource adapter provides JDBC wrappers and the JCA CCI
implementation that allows BMP, JDBC applications, and CMP beans to access
the database.
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WebSphere Application Server V7: Accessing Databases
Figure 2 shows the relational resource adapter model.
CMP
Bean
JDBC
Application
BMP
Persistence
Manager
JDBC API
JDBC API
CCI
Plug-in Layer
JDBC Wrappers
Connection
Manager
SP1
Relational Resource Adapter
JDBC
SQLJ
Figure 2 Persistence resource adapter model
WebSphere Application Server has a Persistence Resource Adapter that
provides relational persistence services to EJB beans as well as providing
database access to BMP and JDBC applications. The Persistence Resource
Adapter has two components:
򐂰 The Persistence Manager, which supports the EJB CMP persistence model
򐂰 The Relational Resource Adapter
WebSphere Application Server V7: Accessing Databases from WebSphere
5
The Persistence Resource Adapter code is included in the following Java
packages:
򐂰 The com.ibm.ws.rsadapter.cci package contains CCI implementation and
JDBC wrappers.
򐂰 The com.ibm.ws.rsadapter.spi package contains SPI implementation.
򐂰 The com.ibm.ws.rsadapter.jdbc package contains all the JDBC wrappers.
򐂰 The com.ibm.websphere.rsadapter package contains DataStoreHelper,
WSCallerHelper, and DataAccessFunctionSet.
The Relational Resource Adapter is the Persistence Manager’s vehicle to handle
data access to and from the back-end store, providing relational persistence
services to EJB beans. The implementation is based on the J2EE Connector
(JCA) specification and implements the JCA CCI and SPI interfaces.
When an application uses a data source, the data source uses the JCA
connector architecture to get to the relational database.
For an EJB, the sequence is as follows:
1. An EJB performs a JNDI lookup of a data source connection factory and
issues a getConnection() request.
2. The connection factory delegates the request to a connection manager.
3. The connection manager looks for an instance of a connection pool in the
application server. If no connection pool is available, then the manager uses
the ManagedConnectionFactory to create a physical, or nonpooled,
connection.
Version 4 data source
WebSphere Application Server V4 provided its own JDBC connection manager
to handle connection pooling and JDBC access. This support is included with
WebSphere Application Server V7.0 to provide support for J2EE 1.2 applications.
If an application chooses to use a Version 4 data source, the application has the
same connection behavior as in Version 4 of the application server.
Use the Version 4 data source for the following purposes:
򐂰 J2EE 1.2 applications
All EJB beans, JDBC applications, or Version 2.2 servlets must use the
Version 4 data source.
򐂰 EJB 1.x modules with 1.1 deployment descriptor
All of these modules must use the Version 4 data source.
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WebSphere Application Server V7: Accessing Databases
Steps in defining access to a database
The following steps are involved in creating a data source:
1. Verify that connection to the database server is supported by WebSphere
Application Server. See:
http://www-01.ibm.com/support/docview.wss?rs=180&uid=swg27012369
2. Ensure that the database has been created and can be accessed by the
systems that will use it.
3. Ensure that the JDBC provider classes are available on the systems that will
access the database. If you are not sure which classes are required, consult
the documentation for the provider.
4. Create an authentication alias that contains the user ID and password that will
be used to access the database.
5. Create a JDBC provider.
The JDBC provider gives the classpath of the data source implementation
class and the supporting classes for database connectivity. This is
vendor-specific.
The information center provides information about JDBC driver support and
requirements. To determine if your provider is supported, refer to the JDBC
Provider Summary article at:
http://publib.boulder.ibm.com/infocenter/wasinfo/v7r0/topic/com.ibm.
websphere.nd.multiplatform.doc/info/ae/ae/udat_minreq.html
New in V7 for DB2: The DB2 Using IBM JCC Driver is a one-phase
commit JCC provider for DB2 that uses the IBM Data Server Driver for
JDBC and SQLJ. The DB2 Using IBM JCC Driver is the next generation of
the DB2 Universal JCC driver. Data sources that you create with this
provider support only one-phase commit processing, unless you use the
type 2 JDBC driver with the application server for z/OS. If you run the
application server on z/OS with the type 2 driver, the driver uses RRS and
supports two-phase commit processing. This driver provides some JDBC
4.0 capabilities.
6. Create a data source.
The JDBC data source encapsulates the database-specific connection
settings. You can create many data sources that use the same JDBC
provider.
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7. Save the changes to the master repository and synchronize with the nodes
involved.
8. Test the connection to the data source.
9. Review and adjust the connection pool settings (this should be done on a
periodic basis).
Creating an authentication alias
The examples in this chapter assume that the database is password protected
and that the user ID and password will be defined at run time.
To create a J2C authentication alias that contains the user ID and password that
is required to access the database, follow these steps:
1. Select Security  Global security.
2. In the Authentication area, expand Java Authentication and Authorization
Server, and click J2C authentication data.
3. Click New.
4. Enter an alias name, user ID, and password, as shown in Figure 3. The alias
name will be used later when you create a resource to identify this as the
authentication alias to use. The user ID and password must be valid for the
database system and have authority to the database.
Figure 3 Define an authentication alias
5. Click OK.
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WebSphere Application Server V7: Accessing Databases
Example: Connecting to an IBM DB2 database
In this section, we illustrate how to configure a JDBC provider using a DB2
provider as an example.
Creating the JDBC provider
To create a JDBC provider, complete the following steps from the administrative
console:
1. Ensure that the implementation classes for the provider are available to the
system. The class files will need to be located on each system where the
application servers will run.
2. In the administrative console, expand Resources  JDBC from the
navigation tree.
3. Click JDBC Providers.
4. Select the scope. (Although you can select All scopes to view all resources,
you must select a specific scope to create a resource.)
Note: JDBC resources are created at a specific scope level. The data
source scope level is inherited from the JDBC provider. For example, if we
create a JDBC provider at the node level and then create a data source
using that JDBC provider, the data source inherits:
򐂰 The JDBC provider settings, such as classpath, implementation class,
and so on
򐂰 The JDBC provider scope level
In this example, if the scope were set to node-level, all application
servers running on that node register the data source in their name
space.
The administrative console now shows all the JDBC providers that are
created at that scope level.
5. Select New to start the wizard and to create a new JDBC provider.
WebSphere Application Server V7: Accessing Databases from WebSphere
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6. In step 1 of the wizard, define the type of provider you will use. See Figure 4.
Figure 4 Define a new JDBC provider: Window 1
Specify the following information
– Database type
Select the vendor-specific database type. If the database type you need is
not in the list, select User-defined, and consult the vendor documentation
for the specific properties that are required.
– Provider type
Select from a predefined list of supported provider types, based on the
database type that you select.
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WebSphere Application Server V7: Accessing Databases
– Implementation type
Select from the implementation types for the provider type that you
selected.
– Name
Specify a Name for this driver.
Click Next.
7. The settings page for your JDBC database class path opens. Figure 5 shows
the configuration page for a Universal JDBC Provider.
Figure 5 Define a new JDBC provider: Window 2
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Enter the JDBC provider properties:
– Classpath
This field is a list of paths or JAR file names that together form the location
for the resource provider classes. This field is pre-set using variable
names that are specific to each type of provider. If you are creating a
user-defined provider, specify the entries by pressing Enter between each
entry.
The remaining properties are dependent upon the type of provider. They
represent the variables that are used in the classpath and their value. If you
enter a value for a variable on this panel, the corresponding variables are
populated automatically with these values. Conversely, if the variables are
already defined, these fields are populated with the variables.
You can view or modify the variables by selecting Environment 
WebSphere Variables in the navigation menu.
Because this example is for DB2, the following fields are available:
– Library path
This field specifies the values for the global variable
UNIVERSAL_JDBC_DRIVER_PATH, which indicates the classpath jar’s
location.
– Native Library Path
This field is an optional path to any native libraries. Entries are required if
the JBDC provider chosen uses non-Java, or native, libraries. The global
variable for this is UNIVERSAL_JDBC_DRIVER_NATIVEPATH.
8. After verifying the settings, click Finish to enable the links to create data
sources under the Additional Properties section.
Tip: To make a data source available on multiple nodes using different
directory structures, complete the following steps using the administrative
console:
1. Define the JDBC provider and data source at the cell scope. Use
WebSphere environment variables for the classpath and native path.
2. Define the variables at the node scope for each node to specify the driver
location for the node.
For example, ${DRIVER_PATH} can be used for the classpath in the
provider definition. You can then define a variable called ${DRIVER_PATH}
at the cell scope to act as a default driver location. Then you can override
that variable on any node by defining ${DRIVER_PATH} at the node scope.
The node-level definition takes precedence over the cell-level definition.
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Creating the data source
Data sources are associated with a specific JDBC provider and can be viewed or
created from the JDBC provider configuration page. You have two options when
creating a data source, depending on the J2EE support of the application. Here
we discuss creating or modifying data sources for Java EE5, J2EE 1.3, and J2EE
1.4 applications. For information about using data sources with J2EE 1.2
applications, see the topic, Data sources (Version 4) in the information center.
The administrative console provides a wizard that helps you create a data
source. Keep in mind, however, that although the wizard provides a good way to
establish connections quickly, it also establishes default-sized connection pool
settings that you need to tune properly before production.
To create a data source, complete the following steps:
1. Expand Resources  JDBC in the navigation tree, and select Data
sources.
2. Select the scope. Although you can select All to view all resources, you must
select a specific scope to create a resource.
The scope determines which applications can use this data source. We
recommend that you select the narrowest scope that is required, while also
ensuring that the applications that require the resource can access it.
3. Click New to create a new data source and to start a wizard (Figure 6).
Figure 6 Data source general properties
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Specify the following information:
– Data source name
This field is a name by which to administer the data source. Use a name
that is suggestive of the database name or function.
– JNDI name
This field refers to the data source’s name as registered in the application
server’s name space.
When installing an application that contains modules with JDBC resource
references, the resources need to be bound to the JNDI name of the
resources; for example, jdbc/<database_name>.
Click Next.
4. Now you need to specify database specific properties, as shown on the right
of Figure 7. Click Next.
Figure 7 Select a JDBC provider
This window allows you to select a JDBC provider or to create a new one. If
you create a new JDBC provider, you will be routed through the windows seen
earlier in “Creating the JDBC provider” on page 9. If you select an existing
JDBC provider, continue with the next step here.
In this case, we select an existing JDBC provider and click Next.
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The entries shown in Figure 8 are specific to the JDBC driver and data source
type, which show the properties for the Universal data source.
Figure 8 Database-specific properties
Specify the following information:
– Driver type
The type of JDBC Driver (2 or 4) used to access the database. To
determine the best type of driver to use for your circumstances, consult the
documentation for the specific driver that you use.
In general, however, use type 2 for databases on the same system as the
application server and type 4 for remote databases.
– Database Name
The name of the database (or the cataloged alias).
– Server name and port
The database server name and its listening port (the default for DB2 is
50000).
– Container managed persistence (CMP)
This field specifies if the data source is to be used for container managed
persistence of EJB beans.
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Deep-dive: Selecting the “Use this data source in container managed
persistence (CMP)” option causes a CMP connection factory that
corresponds to this data source to be created for the relational resource
adapter. The name of the connector factory that is created is
<datasourcename>_CF and the connector factory is registered in JNDI under
the entry eis/<jndi_name>_CMP.
To view the properties of the just created connection factory, select
Resources  Resource Adapters  Resource Adapters. Enable the
Show built-in resources check box in the preferences. Select
WebSphere Relational Resource Adapter  CMP Connection
Factories. Be sure to set the scope so that it is the same scope as that for
the data source.
Click Next.
5. The next step allows you to select or define a J2C authentication alias for the
database. The authentication alias simply contains the user ID and password
required to access the database (Figure 9).
Figure 9 Specify the authentication alias
Click Next.
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6. A summary of the options that you chose displays. Click Next to create the
data source.
The new data source is listed in the table of resources. You can test the new
connection by checking the box to the left of the data source and clicking Test
Connection. You can view or modify settings for the new data source by clicking
the name in the resources list.
Example: Connecting to an Oracle database
This example illustrates a connection to an Oracle Express 10g database.
Ensure that the implementation classes for the provider are available to the
system. The class files need to be located on each system where the application
servers will run.
Creating the JDBC provider
Follow these steps to create the JDBC provider:
1. In the administrative console, expand Resources  JDBC from the
navigation tree.
2. Click JDBC Providers.
3. Select the scope. (Although you can select All scopes to view all resources,
you must select a specific scope to create a resource.)
4. Select New to start the wizard and to create a new JDBC provider.
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5. In step 1 of the wizard, define the type of provider that you will use. See
Figure 10.
Figure 10 Define a new Oracle JDBC provider, Step 1
The database type is Oracle and provider type is Oracle JDBC driver.
Options of implementation type are XA data source or connection pool data
source. XA data source types support two-phase commit transactions.
Click Next.
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6. In the next panel (Figure 11), enter the directory location for the Oracle JDBC
drivers.
In this example, the ojdbc6.jar is assumed by the wizard. However, the
database requires the ojdbc14.jar driver. For now, we complete the wizard to
define the driver, and then alter the driver name in the configuration page.
Figure 11 Define a new Oracle JDBC provider, Step 2
If you have predefined the ORACLE_JDBC_DRIVER_PATH variable, the
driver location is already entered. If you enter a value here, it is saved in the
variable.
Click Next.
7. Review the summary of the settings, and click Finish. The new JDBC
provider displays in the list of providers.
8. Click the JDBC provider name to open the configuration page (Figure 12).
Remember that the wizard assumes that the ojdbc6.jar driver is used.
Change the class path field to point to the ojdbc14.jar.
The implementation class name stays the same.
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Figure 12 Configure the class path
Click OK.
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Creating the data source
To create a data source, complete the following steps:
1. Expand Resources  JDBC in the navigation tree, and select Data
sources.
2. Select the scope. Although you can select All to view all resources, you must
select a specific scope to create a resource.
3. Click New to create a new data source and to start a wizard (Figure 13).
Figure 13 Create a data source, Step 1
Enter a name for the new data source. This is used for administrative
purposes. Enter the JNDI name that will be used to access the data source
and click Next.
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4. In the next panel (Figure 14), select the Oracle JDBC driver and click Next.
Figure 14 Create a data source, Step 2
5. Enter the properties for the database, as shown in Figure 15.
Figure 15 Create a data source, Step 3
Specify the following information:
– The URL for the connection to the XE database is in the following format:
jdbc:oracle:thin:@host_name:port:service
In this case:
jdbc:oracle:thin:@sys2.itso.ral.ibm.com:1521:XE
– Select the data store helper class name.
Click Next.
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6. In the next panel (Figure 16), select the authentication alias that will provide
the user ID and password required to access the database. Click Next.
Figure 16 Create a data source, Step 4
7. Review the summary of your selections, and click Finish.
8. When the data source creation is complete, save the configuration and
synchronize the changes with the nodes.
9. Test the new connection by selecting the new data source and clicking Test
connection (Figure 17).
Figure 17 Test the connection
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Tip: If you receive the following error, make sure that you have adjusted the
JDBC provider to use the correct implementation JAR file (step 9):
DSRA8040I: Failed to connect to the DataSource. Encountered "":
java.sql.SQLException: Invalid argument(s) in callDSRA0010E: SQL
State = 99999, Error Code = 17,068
Example: Connecting to an SQL Server database
This example illustrates a connection to a Microsoft® SQL Server Express 2005
database.
Ensure that the implementation classes for the provider are available to the
system. The class files need to be located on each system where the application
servers will run.
Although some JDBC drivers are bundled with WebSphere Application Server to
facilitate quick connectivity, in general, JDBC drivers are provided by the
database vendor. Information about the location and features of the JDBC
provider is provided by the database vendor versus the WebSphere
documentation.
Creating the JDBC provider
To create a JDBC provider:
1. In the administrative console, expand Resources  JDBC from the
navigation tree.
2. Click JDBC Providers.
3. Select the scope. (Although you can select All scopes to view all resources,
you must select a specific scope to create a resource.)
4. Select New to start the wizard to create a new JDBC provider.
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WebSphere Application Server V7: Accessing Databases
5. In step 1 of the wizard, define the type of provider that you will use. See
Figure 18.
Figure 18 Define a new SQL Server JDBC provider, Window1
The database type is SQL Server and provider type is Microsoft SQL Server
JDBC driver.
Options of implementation type are XA data source or connection pool data
source. XA data source types support two-phase commit transactions.
Click Next.
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6. In the next panel (Figure 19), enter the directory location for the SQL Server
JDBC drivers.
Figure 19 Define a new SQL Server JDBC provider, Window 2
If you have predefined the variables used here, the driver locations are
entered already. If you enter a value here, it is saved in the appropriate
variable.
Click Next.
7. Review the summary of the settings, and click Finish. The new JDBC
provider displays in the list of providers.
8. Click the JDBC provider name to open the configuration page (Figure 20).
Remember that the wizard assumes that the sqljdbc.jar driver is used in the
class path.
Change the class path field to point to the sqljdbc4.jar.
The implementation class name stays the same.
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WebSphere Application Server V7: Accessing Databases
Figure 20 Configure the class path
Click OK.
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Creating the data source
To create a data source, complete the following steps:
1. Expand Resources  JDBC in the navigation tree and select Data sources.
2. Select the scope. Although you can select All to view all resources, you must
select a specific scope to create a resource.
3. Click New to create a new data source and to start a wizard (Figure 21).
Figure 21 Create a data source, Step 1
Enter a name for the new data source. This name is used for administrative
purposes. Enter the JNDI name that will be used to access the data source,
and click Next.
4. In the next panel (Figure 22), select the Microsoft SQL Server JDBC driver,
and click Next.
Figure 22 Create a data source, Step 2
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5. Enter the properties for the database (Figure 23).
Figure 23 Create a data source, Step 3
Specify the following information:
– Enter the database name.
– Enter the port number the database server listens on.
– Enter the host name of the SQL Server installation.
Click Next.
6. In the next panel (Figure 24), select the authentication alias that provides the
user ID and password that are required to access the database. Click Next.
Figure 24 Create a data source, Step 4
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7. Review the summary of your selections, and click Finish.
8. When the data source creation is complete, save the configuration, and
synchronize the changes with the nodes.
9. Test the new connection by selecting the new data source and clicking Test
connection.
Example: Connecting to an Informix Dynamic Server
database
This example illustrates a connection to an Informix Dynamic Server (IDS)
database using the Informix JDBC driver.
Before starting the configuration, ensure that the implementation classes for the
provider are available to the system. The class files need to be located on each
system where the application servers will run.
Also make sure that an authentication alias is created for the user ID that will be
used to connect to the database. For more information, see “Creating an
authentication alias” on page 8.
Creating the JDBC provider
Follow these steps to create the JDBC provider:
1. In the administrative console, expand Resources  JDBC from the
navigation tree.
2. Click JDBC Providers.
3. Select the scope. (Although you can select All scopes to view all resources,
you must select a specific scope to create a resource.)
4. Select New to start the wizard to create a new JDBC provider.
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5. In step 1 of the wizard, define the type of provider that you will use. See
Figure 25.
Figure 25 Define a new Informix JDBC provider, Step 1
The database type is Informix and provider type is Informix JDBC driver.
Options of implementation type are XA data source or connection pool data
source. XA data source types support two-phase commit transactions.
Click Next.
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6. In the next panel (Figure 26), enter the directory location for the Informix
JDBC drivers.
In this example, the ifxjdbc.jar and ifxjdbcx.jar are assumed by the
wizard.
Figure 26 Define a new Informix JDBC provider, Step 2
If you have predefined the INFORMIX_JDBC_DRIVER_PATH variable, the
driver location is already entered. If you enter a value here, it is saved in the
variable.
Click Next.
7. Review the summary of the settings, and click Finish. The new JDBC
provider displays in the list of providers.
8. Click the JDBC provider name to open the configuration page (Figure 27). If
you plan to use SQLJ for queries, change the class path field to add the
ifxsqlj.jar file.
The implementation class name stays the same.
32
WebSphere Application Server V7: Accessing Databases
Figure 27 Configure the class path
Click OK.
WebSphere Application Server V7: Accessing Databases from WebSphere
33
Creating the data source
To create a data source, complete the following steps:
1. Expand Resources  JDBC in the navigation tree, and click Data sources.
2. Select the scope on the right. Although you can select All scopes to view all
resources, you must select a specific scope to create a resource.
3. Click New to create a new data source and to start a wizard (Figure 28).
Figure 28 Create a data source, Step 1
Enter a name for the new data source. This name is used for administrative
purposes. Enter the JNDI name that will be used to access the data source,
and click Next.
4. In the next panel (Figure 29), select the Informix JDBC driver, and click Next.
Figure 29 Create a data source, Step 2
34
WebSphere Application Server V7: Accessing Databases
5. Enter the properties for the database, as shown in Figure 30.
Figure 30 Create a data source, Step 3
Specify the following information:
– Enter the Informix lock mode wait. Default is 2.
– Enter the server name. This name is the INFORMIXSERVER value, that is
the Informix instance name.
– Enter the database name.
– Enter the port number. This number is the olsoctcp protocol port number.
Check your SQLHOSTS file on UNIX®, Linux®, or Windows® registry on
Windows for the correct value to enter.
– Enter the ifxIFXHOST name. This name is host name or the IP Address of
the host that is running your Informix instance.
Click Next.
6. In the next panel (Figure 31), select the authentication alias that provides the
user ID and password required to access the database. In this step, we
assume that an authentication alias is created already. Click Next.
WebSphere Application Server V7: Accessing Databases from WebSphere
35
Figure 31 Create a data source, Step 4
7. Review the summary of your selections, and click Finish.
8. When the data source creation is complete, save the configuration, and
synchronize the changes with the nodes.
9. Test the new connection by selecting the new data source and clicking Test
connection (Figure 32).
Figure 32 Test the connection
Configuring connection pooling properties
Performance of an application that connects to a database can be greatly
affected by the availability of connections to the database and how those
connections affect the performance of the database itself. There are no simple
36
WebSphere Application Server V7: Accessing Databases
rules that tell you how to configure the connection pool properties. Your
configuration is highly dependent on application, network, and database
characteristics. You need to coordinate the values that you specify in WebSphere
closely with the database administrator.
Remember to include all resources in capacity planning. If 10 applications all
connect to a database using separate connection pools of 10 maximum
connections, this means that there is a theoretical possibility of 100 concurrent
connections to the database. Make sure that the database server has sufficient
memory and processing capacity to support this requirement.
To access the connection pool properties:
1. Navigate to Resources  JDBC  Data sources, and click the data source
name.
2. Select Connection pool properties in the Additional Properties section,
which opens the panel shown in Figure 33.
Figure 33 Data source connection pool properties
Specify the following information:
WebSphere Application Server V7: Accessing Databases from WebSphere
37
– Connection Timeout
Specify the interval, in seconds, after which a connection request times
out and a ConnectionWaitTimeoutException is thrown. This can occur
when the pool is at its maximum (Max Connections) and all of the
connections are in use by other applications for the duration of the wait.
For example, if Connection Timeout is set to 300 and the maximum
number of connections is reached, the Pool Manager waits for 300
seconds for an available physical connection. If a physical connection is
not available within this time, the Pool Manager throws a
ConnectionWaitTimeoutException.
Tip: If Connection Timeout is set to 0, the pool manager waits as long
as necessary until a connection is allocated.
– Max Connections
Specify the maximum number of physical connections that can be created
in this pool.
These connections are the physical connections to the back-end
database. After this number is reached, no new physical connections are
created and the requester waits until a physical connection that is currently
in use is returned to the pool, or a ConnectionWaitTimeoutException is
thrown.
For example, if Max Connections is set to 5, and there are five physical
connections in use, the Pool Manager waits for the amount of time
specified in Connection Timeout for a physical connection to become free.
If, after that time, there are still no free connections, the Pool Manager
throws a ConnectionWaitTimeoutException to the application.
– Min Connections
Specify the minimum number of physical connections to be maintained.
Until this number is reached, the pool maintenance thread does not
discard any physical connections. However, no attempt is made to bring
the number of connections up to this number.
For example, if Min Connections is set to 3, and one physical connection is
created, that connection is not discarded by the Unused Timeout thread.
By the same token, the thread does not automatically create two additional
physical connections to reach the Min Connections setting.
38
WebSphere Application Server V7: Accessing Databases
Tip: Set Min Connections to zero (0) if the following conditions are true:
򐂰 You have a firewall between the application server and database
server.
򐂰 Your systems are not busy 24/7.
– Reap Time
Specify the interval, in seconds, between runs of the pool maintenance
thread.
For example, if Reap Time is set to 60, the pool maintenance thread runs
every 60 seconds. The Reap Time interval affects the accuracy of the
Unused Timeout and Aged Timeout settings. The smaller the interval you
set, the greater the accuracy. When the pool maintenance thread runs, it
discards any connections that have been unused for longer than the time
value specified in Unused Timeout, until it reaches the number of
connections specified in Min Connections. The pool maintenance thread
also discards any connections that remain active longer than the time
value specified in Aged Timeout.
Tip: If the pool maintenance thread is enabled, set the Reap Time value
less than the values of Unused Timeout and Aged Timeout.
The Reap Time interval also affects performance. Smaller intervals mean
that the pool maintenance thread runs more often and degrades
performance.
– Unused Timeout
Specify the interval in seconds after which an unused or idle connection is
discarded.
Tips:
򐂰 Set the Unused Timeout value higher than the Reap Timeout value
for optimal performance. Unused physical connections are only
discarded if the current number of connections not in use exceeds
the Min Connections setting.
򐂰 Make sure that the database server’s timeout for connections
exceeds the Unused timeout property specified here. Long lived
connections are normal and desirable for performance.
For example, if the unused timeout value is set to 120, and the pool
maintenance thread is enabled (Reap Time is not 0), any physical
WebSphere Application Server V7: Accessing Databases from WebSphere
39
connection that remains unused for two minutes is discarded. Note that
accuracy of this timeout, as well as performance, is affected by the Reap
Time value. See the Reap Time bullet for more information.
– Aged Timeout
Specify the interval in seconds before a physical connection is discarded,
regardless of recent usage activity.
Setting Aged Timeout to 0 allows active physical connections to remain in
the pool indefinitely. For example, if the Aged Timeout value is set to 1200,
and the Reap Time value is not 0, any physical connection that remains in
existence for 1200 seconds (20 minutes) is discarded from the pool. Note
that accuracy of this timeout, as well as performance, is affected by the
Reap Time value. See Reap Time for more information.
Tip: Set the Aged Timeout value higher than the Reap Timeout value
for optimal performance.
– Purge Policy
Specify how to purge connections when a stale connection or fatal
connection error is detected.
Valid values are EntirePool and FailingConnectionOnly. If you choose
EntirePool, all physical connections in the pool are destroyed when a stale
connection is detected. If you choose FailingConnectionOnly, the pool
attempts to destroy only the stale connection. The other connections
remain in the pool. Final destruction of connections that are in use at the
time of the error might be delayed. However, those connections are never
returned to the pool.
Tip: Many applications do not handle a StaleConnectionException in
the code. We recommend that you test to ensure that your applications
handle them.
Selecting the Advanced connection pool properties link allows you to modify
the properties additional connection pool properties. These properties require
advanced knowledge of how connection pooling works and how your system
performs. For information about these settings, see the Connection pool
advanced settings topic in the information center.
40
WebSphere Application Server V7: Accessing Databases
WebSphere Application Server data source properties
You can set the properties that apply to the WebSphere Application Server
connection, rather than to the database connection. To access the connection
pool properties, navigate to Resources  JDBC  Data sources, and click the
data source name. Select WebSphere Application Server data source
properties in the Additional Properties section. See Figure 33 on page 37.
Clicking the link gives you the window shown in Figure 34.
Figure 34 WebSphere data source custom properties
Specify the following information:
WebSphere Application Server V7: Accessing Databases from WebSphere
41
򐂰 Statement Cache Size
Specify the number of prepared statements that are cached per connection.
A prepared statement is a precompiled SQL statement that is stored in a
prepared statement object. This object is used to execute the given SQL
statement multiple times. The WebSphere Application Server data source
optimizes the processing of prepared statements.
In general, the more statements your application has, the larger the cache
should be. For example, if the application has five SQL statements, set the
statement cache size to 5, so that each connection has five statements.
Tip: This setting is vital to performance of the database and will most likely
require tuning to suit the specific application. Our general experience is
that the default is not high enough for best performance.
򐂰 Enable multi-threaded access detection
If you enable this feature, the application server detects the existence of
access by multiple threads.
򐂰 Enable database reauthentication
Connection pool searches do not include the user name and password. If you
enable this feature, a connection can still be retrieved from the pool, but you
must extend the DataStoreHelper class to provide implementation of the
doConnectionSetupPerTransaction() method where the reauthentication
takes place.
Connection reauthentication can help improve performance by reducing the
overhead of opening and closing connections, particularly for applications that
always request connections with different user names and passwords.
򐂰 Log missing transaction context
Specifies whether the container issues an entry to the activity log when an
application obtains a connection without a transaction context.
򐂰 Non-transactional data source
Setting the flag to true will cause the Application Server to never enlist the
connections from the datasource in global or local transactions. Applications
must explicitly call setAutoCommit(false) on the connection if they want to
start a local transaction on the connection, and they must commit or rollback
the transaction that they started. Note: this property should rarely be set to
true, however the Java Persistence API (JPA) requires both JTA and non-JTA
datasources.
42
WebSphere Application Server V7: Accessing Databases
򐂰 Error detection model
The error detection model has been expanded and the data source has a
configuration option that you can use to select the exception mapping model
or the exception checking model for error detection.
򐂰 Connection validation properties
There two properties and you can choose both. If you check the Validate new
connections box, the application server tries to connect to database. If you
select this property, you can specify how often, in seconds (interval).
If you check the Validate existing pooled connections box, the application
server retries to make a connection. If you select this property, you can
specify retry interval for the server reroute. The pretest SQL string is sent to
the database to test the connection.
New in V7: Connection validation by SQL query is deprecated in
WebSphere Application Server V7.0. You can use validation by JDBC
Driver instead. If you use the property of validation by JDBC driver, you
need JDBC 4.0 or greater version. If you do not have JDBC 4.0, you have
to update JDBC driver, the first.
򐂰 Advanced DB2 features
– Optimize for get/use/close/connection pattern with heterogeneous pooling
If you check this property, the heterogeneous pooling feature allows you to
extend the data source definition. You can specify retry interval for client
reroute, how often to retry, alternate server name or names for the DB2
server, port number, JNDI name. Details are described in “Extended DB2
data source” on page 44.
– DB2 automatic client reroute options
(New in V7) Client reroute for DB2 allows you to provide an alternate
server location, in case the connection to the database server fails. If you
decide to use client reroute with the persistence option, the alternate
server information will persist across Java Virtual Machines (JVMs). In the
event of an application server crash, the alternate server information will
not be lost when the application server is restored and attempts to connect
to the database.
WebSphere Application Server V7: Accessing Databases from WebSphere
43
Extended DB2 data source
(New in V7) The DB2 Universal JDBC Driver and DB2 using IBM JCC Driver
support extends a DB2 data source with what is known as heterogeneous
pooling. The extended DB2 data source configures a WebSphere DB2 data
source with a set of core data source properties. An application can define one or
more non-core set of data source properties and associate each with a different
resource-reference that points to the main WebSphere DB2 data source.
The benefit of using an extended DB2 data source is that it allows applications to
share the same WebSphere connection pool even though each application can
have its own set of data source properties.
The sharing leads to a reduction of the number of open connections, and it
pushes to reduce resource consumption on both the client side (WebSphere)
and the server side (database layer).
For more information, refer to the following article in the information center:
http://publib.boulder.ibm.com/infocenter/wasinfo/v7r0/topic/com.ibm.web
sphere.express.doc/info/exp/ae/tdat_heteropool.html
44
WebSphere Application Server V7: Accessing Databases
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This document REDP-4577-01 was created or updated on March 26, 2010.
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