While many of application design choices made are certainly debatable especially in the “real-world” context, care was taken to ensure that these choices enable the sample application to encompass as many potential issues as possible as one would face in the process of migrating a typical J2EE application.
This section will go through the potential issues that you might face when migrating a J2EE application, and the corresponding component of iBank that was included to check for this issue during the migration process.
With respect to the selected migration areas to address, this section specifically looks at the following technologies:
The iBank application includes a number of servlets, that enable us to detect potential issues with:
The use of generic functionality of the Servlet API
Storage/retrieval of attributes in the HTTP session and HTTP request
Retrieval of servlet context initialization parameters
With respect to the JSP specification, the following aspects have been addressed:
Use of JSP declarations, scriptlets, expressions, and comments
Static includes (<%@ include file="…" %>): notably tested with the inclusion of the CheckSession.jsp file in every page)
Dynamic includes (<jsp:include page=… />): this is catered for by the dynamic inclusion of Header.jsp in every page
Use of custom tag libraries: a custom tag library is used in the file ShowTransactionHistory.jsp
Error pages for JSP exception handling: the Error.jsp page is the application error redirection page
The iBank application accesses a database via a connection pool and the data source, both programmatically (BMP entity bean, BankTeller session bean, custom tag library) and declaratively (with the CMP entity beans).
The iBank application uses a variety of Enterprise Java Beans.
Bean-managed persistence (Customer bean): allows us to test the following:
JNDI lookup of initial context
Pooled data source access via JDBC
Definition of a BMP custom finder (findByCustUsername())
Container-managed persistence (Account and Branch beans): allow us to test the following:
Object/Relational mapping with the development tool and within the deployment descriptor
Use of composite primary keys (Account)
Definition of custom CMP finders (with the Account bean, and its findOrderedAccountsForCustomer() method). This is the occasion to look at differences in declaring the query logic in the deployment descriptor, and also to have a complex example returning a collection of objects.
Stateless session beans: InterestCalculator allows us to test the following:
Using and deploying a stateless session bean
Calling a business method for calculations
Stateful session beans: BankTeller allows us to test the following:
Looking up various interfaces using JNDI and initial contexts
Using JDBC to perform database queries
Using various transactional attributes on bean methods
Using container-demarcated transactions
Maintaining conversational state between calls
Business methods acting as front-ends to entity beans (e.g., the “getAccountSummary()” method)
The iBank application is assembled by following the J2EE standard procedures. It contains the following components:
A Web application archive file for the Web application module, and EJB-JAR archives for the EJBs
An enterprise application archive file (EAR file) for the final packaging of the Web application and EJB modules