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Enterprise JavaBeans and Java Persistence API (JPA)

Now that the RedBank Web application is up and running, more issues arise. Some of these relate to the services provided to customers and bank workers, and some relate to the design, configuration, and functionality of the systems that perform the back-end processing for the application.

First, we want to provide the same business logic in a new application that will be used by administration staff working in the bank's offices. We would like to be able to reuse the code that has already been generated for the RedBank Web application without introducing the overhead of having to maintain several copies of the same code. Integration of these business objects into a new application should be made as simple as possible.

Next, we want to reduce development time by using an object-relational mapping system that will keep an in-memory, object-oriented view of data with the relational database view automatically, and provide convenient mapping tools to set up the relationships between objects and data. This system should be capable of dealing with distributed transactions, because the data might be located on several different databases around the bank's network.

Because we are planning to make business logic available to multiple applications simultaneously, we want a system that will manage such issues as multithreading, resource allocation, and security so that developers can focus on writing business logic code without having to worry about infrastructure matters such as these.

Finally, the bank has legacy systems, not written in Java, which we would like to be able to update to use the new functionality provided by these business objects. We want to use a technology that can allow this type of interoperability between different platforms and languages.

We can get all this functionality by using Enterprise JavaBeans (EJBs) and the Java Persistence API (JPA) to provide our back-end business logic and access to data. Later, we will see how EJBs can also allow us to integrate messaging systems and Web services clients with our application logic.

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