tailieunhanh - WebSphere Studio Application Developer Version 5 Programming Guide part 42

WebSphere Studio Application Developer part 42 provides integrated development tools for all e-business development roles, including Web developers, Java developers, business analysts, architects, and enterprise programmers. The customizable, targeted, role-based approach of WebSphere Studio Application Developer will be characteristic of all new products built on the WebSphere Studio Workbench. It is well integrated with WebSphere Application Server and provides built-in server test environments that can be used for testing and profiling Web applications | Sample Application RedBank In this chapter we are going to reuse the design of the RedBank application described in Developing Web applications on page 179. This time though we will use EJBs to implement the business model instead of regular JavaBeans. The rest of the application s layers control and view still apply exactly as designed even though we will have to make some small changes to the facade to make it work with EJBs instead of JavaBeans. In Figure 12-3 you can see the model layer s updated design. Web Project EJB Project Entity beans Figure 12-3 EJB module design JavaBean Session bean If you compare this model to the Web application model shown in Figure 5-21 on page 111 you can see that the coordinator Bank has been replaced with a session EJB BankEJB . This EJB has a remote interface and uses container demarcated transactions. Without any extra code we are able to count on transaction management for our operations. Finally our business entities Customer Account and TransRecord are implemented as CMP entity beans with local interfaces as opposed to regular JavaBeans. By doing so we automatically gain persistence security and transaction management services. On the other hand this also implies that the control and view layers will not be able to reference these entities directly because they may be placed in a different JVM. This time around only the session bean BankEJB will be able to access the business entities through their local home interfaces. 384 WebSphere Studio Application Developer Version 5 Programming Guide Note In general the session bean is called the facade. In our design we use a JavaBean and a session bean to function as the facade. This isolates the Web application completely from the model implementation. Only the JavaBean part of the facade must be changed to interact with the session bean facade instead of another model implementation. You may be asking yourself then why we do not expose a remote interface for our entity beans as .