A New Approach for Clustering of Navigation Patterns of

Automatic Recommendation for Online Users
Using Web Usage Mining
Ms.Dipa Dixit 1
Mr Jayant Gadge2
Lecturer 1
Asst.Professor2
Fr CRIT , Vashi Navi Mumbai1
Thadomal Shahani Engineering College,Bandra 2
Email:dipa.pathak@gmail.com
jayantrg@hotmail.com2
1
ABSTRACT
A real world challenging task of the web master of an organization is to match the needs of user and keep
their attention in their web site. So, only option is to capture the intuition of the user and provide them
with the recommendation list. Most specifically, an online navigation behavior grows with each passing
day, thus extracting information intelligently from it is a difficult issue. Web master should use web usage
mining method to capture intuition. A WUM is designed to operate on web server logs which contain
user’s navigation. Hence, recommendation system using WUM can be used to forecast the navigation
pattern of user and recommend those to user in a form of recommendation list. In this paper, we propose
a two tier architecture for capturing users intuition in the form of recommendation list containing pages
visited by user and pages visited by other user’s having similar usage profile. The practical
implementation of proposed architecture and algorithm shows that accuracy of user intuition capturing is
improved.
KEYWORDS
Data Mining, Web Usage mining, Web Intelligence, Personalization, Clustering, Classification
1. INTRODUCTION
With the explosive growth of knowledge available on World Wide Web, which lacks an
integrated structure or schema, it becomes much more difficult for users to access relevant
information efficiently. Meanwhile, the substantial increase in the number of websites presents a
challenging task for web masters to organize the contents of websites to cater to the need of
user‟s. Analyzing and modeling web navigation behavior is helpful in understanding demands
of online users. Following that, the analyzed results can be seen as knowledge to be used in
intelligent online applications, refining website maps, and web based personalization system
and improving searching accuracy when seeking information. Nevertheless, an online
navigation behavior grows each passing day, thus extracting information intelligently from it is
a difficult issue. Web Usage Mining (WUM) is process of extracting knowledge from Web
user‟s access data, by exploiting Data Mining technologies. It can be used for different purposes
such as personalization, system improvement and site modification. A typical application of
Web Usage Mining is represented by so called recommender system. The main goal of the
recommender system is to improve Web site usability. Typically, the Web usage mining
prediction process is structured according to two components performed online and off-line with
respect to Web server activity. Offline component builds the knowledge base by analyzing
historical data, such as server access log file or web logs which are captured from the server,
then these web logs are used in the online component for capturing the intuition list of the user
so as to recommend page views to the user whenever he / she comes online for the next time.
In our paper, we present architecture for capturing recommendations in the form of intuition list
for user. Intuition List consists of list of pages visited by user as well as list of pages visited by
other user of having similar usage profile. The results represent that improved accuracy of
recommendations. The rest of this paper is organized as follows: In section 2, we review some
researches that advance in understanding of recommendation systems using web usage mining.
Section 3 describes the block diagram and implementation for the Recommendation System.
Results and discussion are shown in section 4. Finally, section 5 summarizes the paper and
introduces future work.
2. RELATED WORK
Recently, several Web Usage Mining systems have been proposed to predicting user navigation
behavior and their preferences. In the following we review some of the most significant WUM
systems and architecture that can be compared with our system Analog[8] is one of the first
WUM systems .It is structured according to an offline and an online component. The off-line
component build session clusters by analyzing past user activity recorded in server log files.
Then the online component builds active user sessions which are then classified according to
generated model. The classification allows to identify pages related to the ones in the active
session and to return the requested page with a list of suggestions. This approach has several
limitations, related to scalability.
Nevertheless, architectural solution introduced was
maintained in several other more projects. In Mobasher et al[1] present Web personalizer a
system which provides dynamic recommendations, as a list of hypertext links, to users. The
analysis is based on anonymous usage data combined with the structure formed by hyperlinks of
the site. Data mining techniques (i.e. clustering, sequence pattern discovery and association
rules) are used in preprocessing phase in order to obtain aggregate usage profiles. In this phase
Web server logs are converted into clusters of visited pages, and cluster made up of set of pages
with common usage characteristics. The online phase considers active user session in order to
find matches among user‟s activities and discovered usage profiles. Matching entries are used to
compute a set of recommendations which will be inserted into last requested page as list of
hypertext links. Web Personalizer is a good example of two tier architecture for Personalization
Systems. Baraglia and Palmerini proposed a WUM system called SUGGEST, that provide
useful information to make easier the web user navigation and to optimize the web server
performance [6, 7]. SUGGEST adopts a two level architecture composed of offline creation of
historical knowledge and online engine that understands user‟s behavior. As the request arrives
at this system module it incrementally updates a graph representation of web site based on the
active user sessions and classifies the active session using a graph partitioning algorithm.
Potential
limitation
of
this
architecture
might
be:
a) the memory required to store Web server pages in quadratic in the number of pages .This
might
be
severe
limitation
in
larger
sites
made
of
million
pages;
b)it does not permit us to manage web sites made up of pages dynamically generated. All of
these works attempt to find the architecture and algorithm to improve accuracy of personalized
recommendation, but accuracy still does not meet satisfaction. In our work we advance
architecture and propose a classification approach using visited and unvisited pages of user in
the architecture for improving accuracy of recommendation for users.
3. BLOCK
DIAGRAM
AND
RECOMMENDATION SYSTEM
IMPLEMENTATION
OF
Block diagram of the Recommendation System is given below.
front-end phase
Front-end phase
Data pre-processing
Web logs
User Navigation
Mining
Live Session
Window
Classification
Algorithm
Navigation profile o/p
Intelligent
Agent Engine
Knowledge Base
Captured List
Back-end phase
User
List of unvisited
pages
Figure1: Architecture of Recommendation System for Online Users
3.1 Implementation of Recommendation System
Implementation of System is done in two phases, Back-end and Front-end phase.
3.1.1Back-end phase :
Steps involved in back-end phase are explained below.
Step 1: Data sets consisting of 5000 web log records are collected from De Paul University
website. Web log is an unprocessed text file which is recorded from the IIS Web Server. Web
log consist of 17 attributes with the data values in the form of records.
Fragment of web log from IIS web server is shown below:
Fields: date time c-ip cs-username s-sitename s-computername s-ip s-port cs-method cs-uristem cs-uri-query sc-status time-taken cs-version cs-host cs(User-Agent) cs(Referer) .
Step2: Generally, several preprocessing tasks need to be done before performing web mining
algorithms on the Web server logs. Data preprocessing, a web usage mining model aims to
reformat the original web logs to identify user‟s access session. The Web server usually
registers all users‟ access activities of the website as Web server log. Due to different server
setting parameters, there are many types of web logs, but typically the log files share the same
basic information, such as: client IP address, request time, requested URL, HTTP status code,
referrer, etc.
Data pre-processing is done using following steps.
Data
Cleansing
User
Identification
Session
Identification
Content
Retrieval
Path
Completion
Figure 2: Block diagram for Pre-processing
1. Data Cleansing: Irrelevant records are eliminated during data cleansing. Since target of
web usage mining is to get traversal pattern, following two kinds of records are unnecessary
and should be removed :
a. The records having filenames suffixes of GIF, JPEG, CSS.
b. By examining the status field of every record in the web log, the record with status code
over 299 and below 200 are removed.
2. User and Session Identification: The task of user and session identification is to find out the
different user sessions from the original web access log. A referrer-based method is used for
identifying sessions. The different IP addresses distinguish different users.
a. If the IP addresses are same, different browsers and operation system‟s indicate different
users which can be found by client IP address and user agent who gives information of
user‟s browsers and operating system.
b. If all of the IP address, browsers and operating systems are same, the referrer information
should be taken into account. The ReferURI is checked, new user‟s session is identified if
the URL in the ReferURI is „-‟ that is field hasn't been accessed previously, or there is a
large interval of more than 30 minutes between the accessing time of this record.
3. Content Retrieval: Content Retrieval retrieves content from users query request i.e.
cs_uri_query.
Eg:Query:http/1www.cs.depaul.edu/courses/syllabus.asp?course=323-21603&q=3&y=2002&id=671.
Retrieve the content like /courses/syllabus.asp which helps in fast searching of unvisited pages
i.e; pages of other user‟s which are similar to user‟s interest.
4. Path Completion: Path Completion should be used acquiring the complete user access path.
The incomplete access path of every user session is recognized based on user session
identification. If in a start of user session, Referrer as well URI has data value, delete value of
Referrer by adding „-„. Web log preprocessing helps in removal of unwanted records from the
log file and also reduces the size of original file by 40-50%.
Step 3: Generation of Page Id: Page Id is sequence generated numbers like p1, p2, p3….which
are created for pages/page views.
Step 4: User Navigation Mining: Web pages accessed are modeled as undirected graph G=
(V, E). The set V of vertices contains the identifiers of the different pages hosted on the Web
server and E is edges of the graph.
a. Undirected graph is created for a single user session using Hash Map.
b. Hash Map data structure stores the referrer–URI pair and their corresponding weights.
c. Weight of edges given by 1, only if link between page and referrer exist, else weight is 0.
d. Weights of pages are frequency connectivity of pages in graph. i.e.
Weight of pages (W) = Frequency (F) of referrer–URI pair (occurrence in user session)
e. Apply Depth First Search Algorithm (DFS) on graph and obtain all possible navigation
patterns.
f. Path length of pattern is calculated by considering the total weight of the edges in a graph.
g. If navigation pattern weight /path length is less than three, then pattern is not considered for
analysis. (Minpathlength = 3).
Hence, clusters of patterns for user sessions are obtained and fed into Knowledge base for
further analysis.
3.1.2 Front End Phase
Step 1: Longest Common Subsequence Algorithm:
a. Capture the Live Session Window (LSW) for a user dynamically [5].
b. Intelligent Agent Engine compares LSW of a user with patterns of same user in
knowledge base.
c. Check for the longest pattern or the largest path length of a pattern from knowledge base.
d. Compare both the sequences, longest common subsequence is obtained.
e. Consider the pages which are not present in subsequence, these pages are the Intuition
pages for the user as they are visited by user most frequently.
f. Recommendation list is given in the form of URI (content) as well as IDs of pages.
Hence, recommendation/intuition list as compared to user‟s historical pattern are captured.
Step2: Searching of Unvisited pages (as compared to others user‟s pattern)
a. Unvisited pages when compared to other user‟s pattern are searched using
algorithm.
searching
b. Searching algorithm compares the live session window of user and patterns of other
user‟s present in Knowledge Base.
c. Best possible pattern is achieved by considering longest path length (weight).
d. Subsequent pages are removed and the Unvisited Page List is created in the form of
URI and IDs.
Recommendation List as compared to others user‟s pattern (unvisited pages) are captured and
added to original recommendation list
4. RESULTS AND DISCUSSIONS
Step wise results are shown below for 5000 web log records from De Paul University dataset
(CTI dataset).
Step 1: Collection of web logs which are in raw or unprocessed form.17 attributes are shown
below:
2002-04-01 00:00:10 1cust62.tnt40.chi5.da.uu.net - w3svc3 bach bach.cs.depaul.edu
80 get /courses/syllabus.asp course=323-21-603&q=3&y=2002&id=671 200 156
http/1.1 www.cs.depaul.edu
mozilla/4.0+(compatible;+msie+5.5;+windows+98;+win+9x+4.90;+msn+6.1;+msnbm
sft;+msnmen-us;+msnc21) http://www.cs.depaul.edu/courses/syllabilist.asp
depaul.edu/courses/syllabilist.asp
2002-04-01 00:00:26 ac9781e5.ipt.aol.com - w3svc3 bach bach.cs.depaul.edu 80 get
/advising/default.asp - 200 16 http/1.1 www.cs.depaul.edu
mozilla/4.0+(compatible;+msie+5.0;+msnia;+windows+98;+digext)
http://www.cs.depaul.edu/news/news.asp?theid=573
Step 2: Preprocessing is done for 5000 web log records. Cleansing, User and Session
Identification, Content Retrieval and Path Completion applied on records.
Preprocessing of 5000 records was done in 14secs.
User Sessions were identified for 200 users.
Thus, processed records for a user id 9 in user‟s sessionized form are as shown below.
Figure 3: Processed file with required attributes for user id 9
Step 3: Page Id is generated for the URI/pages/page view accessed by user
Figure 4: List of Page id and corresponding pages/uri
Step 4: In User Navigation Mining undirected graphs are created and clusters of all possible
patterns are generated for a user session
Figure 5: Cluster of patterns for user id=9
When Clusters of navigation Patterns were compared to original user navigation patterns most
of pages views (99%) were covered in the clusters. Very few i.e; 1% of outliers were obtained.
Step 5: Considered Two cases of Live Session Window (LSW) of size 2 and varying patterns
ie; one pattern having few page views and other having more number of page views these cases
are shown in Step 6. Live Session Window (LSW) consists of 10% of pages of actual page
views of user (Originalnp). Classification is done by applying Longest Common Subsequence
algorithm on LSW and rest of pages present in original page view list of user. Thus the intuition
list obtained is from the history of user‟s navigation pattern.
Step 6: Apply Searching algorithm to get the intuition list of the user‟s whose usage pattern is
same as the user. Thus, both the lists are combined into the Final Recommendation List of the
user. Finally, Accuracy is calculated for the final recommendation list.
Accuracy measures the degree to which the recommendation system produces accurate
recommendations. It is given by
| P( LSnp, lsw)  (Origina ln p) |
| P( LSnp, lsw) |
(1)
lsw = Live Session Window
P( LSnp, lsw) -Navigation pattern in captured list recommended by engine.
Origina ln p -Original page views / pattern of user.
Case 1: When LSW of size 2 was considered for user id 9, having 13 page views.
Recommendation List obtained had accuracy of 66.6%, which is shown below.
Figure 6: recommendation list for user id=9 and accuracy is 66.6%
Case 2: When LSW of size 2 was considered for user id 89, having 17 page views,
recommendation list obtained had accuracy 85.71%, as shown below.
Figure 7: recommendation list for user id=89 and accuracy is 85.71%
Thus, from above cases we can prove that accuracy of the recommendation list increases if the
number of page views is more in the user navigation pattern.
5. CONCLUSION
In this paper, we propose a two tier architecture for capturing user‟s intuition in the form of
recommendation list containing list of pages visited by user and also list of pages visited by
other user‟s having similar usage profile. The practical implementation of proposed architecture
and algorithms shows that accuracy of user intuition capturing improves up to 85 percent for
Live Session Window size of two, if numbers of page views having maximum weights are more
in the navigation patterns of the user. In the future, we would like to substantially improve the
accuracy and coverage parameter by trying to increase the Live Session Window (LSW) size
and considering more number of log records.
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