Professional Oracle® WebLogic Server

Chapter 7. Building an Example EJB Application

In this chapter, we walk through the design and implementation of the business layer of the bigrez.com example application, highlighting key concepts and best practices. Though this chapter is not a full tutorial for constructing EJB components or the business layer of Java EE applications, it provides insight into the construction of the example application, along with useful techniques that you can apply in your projects.

This chapter is organized like Chapters 2 through 4, with the discussion proceeding from requirements to architecture and then to implementation.

• We identify a set of business layer requirements to guide the architecture selection process.

• We identify and examine candidate architectures in light of the requirements to gauge their relative value for our application.

• We examine selected business layer components required for the bigrez.com application to highlight implementation details and best practices.

Finally, we look at the necessary changes should we want to switch the JPA provider from WebLogic Server's Kodo implementation to Oracle's TopLink implementation, which will replace Kodo in a future version of WebLogic Server.

We start with the requirements.

Business Layer Requirements

As we stated in Chapter 2, you should identify and consider as many requirements as you can before choosing a design. We spent a fair amount of time identifying the many presentation layer requirements that a web application must address, ...