To understand this sample you
need to have expertise in working with Servlets and knowledge of
Enterprise Java Beans. Refer to the Additional References section for related resource links.
Technical Overview
In this sample application we demonstrate how a web
application can make use of servlet life cycle event listeners to manage
session time-outs. An event is a notification of change in the state of a
servlet's life cycle. The application events provide notifications of a change
in state of the servlet context or of an HTTP session object. These
events can be captured and monitored by defining listener objects, whose
methods get called when such events occur.
For servlet context events, the event listener classes
can receive notification when the web application is deployed or is being
undeployed, and when attributes are added, removed, or replaced. Servlet
context listeners manage resources at the application level.
For HTTP session events, the event listener classes
can receive notification when an HTTP session is created, invalidated or
timed out and when an HTTP session attribute is added, removed, or replaced.
Session listeners manage resources associated with the single user's session.
In this sample application we have implemented
sessionDestroyed() method of HttpSessionListener to remove the Stateful
Session Beans when the user session expires.
Application Overview
The sample application allows following functionalities,
Login
Browse though the available products
Create shopping cart
Update the cart
Remove items from the cart
Checkout the cart
Logout
Application Design
This application is designed to demonstrate how
HttpSessionListener can be used to release any references to the external
resources stored in the http session, when the session times out. The
application uses a Stateful Session Bean to store the shopping cart information
for the user. When the user creates a cart for the first time, a reference
to the ShoppingCartBean is stored in the HttpSession object. This reference is
made use to serve the subsequent requests when the user adds, modifies or
deletes items in the shopping cart. The session bean instances are removed
in the sessionDestroyed() method of SessionTimeoutListener class when the user logs out from the application or the
session times out.
Sample Application Files
This section provides a tabular listing of the
sample application files, along with their respective directory locations
and a description of what they do in the overall scheme of the application:
Readme file and Stylesheets
Directory
File
Description
SessionListener/doc
Readme.html
This file
SessionListener/doc
Install.html
The sample
installation document
SessionListener/doc
otn.css
Stylesheet
used in the Readme.html and Install.html
Servlet and Java source files
Directory
File
Description
SessionListener/src/oracle/otnsamples/servlets
ShoppingCartServlet.java
This Servlet displays the various screens of the application
SessionListener/src/oracle/otnsamples/servlets
EditCart.java
The servlet used to manage the
shopping cart in the HTTP Session
SessionListener/src/oracle/otnsamples/servlets
SessionTimeoutListener.java
The listener class that implements
the HttpSessionListener interface.
SessionListener/src/oracle/otnsamples/servlets
ProductDetails.java
The Java class used to hold product
information
SessionListener/public_html/WEB-INF
web.xml
The web deployment descriptor
Enterprise Java Beans and related files
Directory
File
Description
SessionListener/src/oracle/otnsamples/ejb
ShoppingCartBean.java
The bean implementation
class
SessionListener/src/oracle/otnsamples/ejb
ShoppingCartLocalHome.java
The local home class
SessionListener/src/oracle/otnsamples/ejb
ShoppingCartLocal.java
The local interface
class
SessionListener/src/oracle/otnsamples/ejb
InvalidValuesException.java
The application level
exception thrown by the EJB
SessionListener/src/META-INF
ejb-jar.xml
The EJB deployment
descriptor
SessionListener/src/META-INF
orion-ejb-jar.xml
Server specific deployment descriptor
Other configuration and build files
Directory
File
Description
SessionListener
build.xml
The ant project build file
SessionListener/src/META-INF
data-sources.xml
The configuration
file, where the datasource used by this application is defined
Setting up the Sample Application
Refer the Install.html for step-by-step instructions
on extracting files, installing and running the sample successfully.
Bookmark
