You have now completed the data layer of your application, and are ready to dive into the business layer. If you recall from Chapter 2, the business layer incorporates your application’s business logic. Specifically, you will need to provide access to your entity beans, business calculations, and a scheduling facility. In this chapter, I’ll detail the access to entity beans already in place, and discuss how to handle more complex business tasks. Chapter 9 then details the scheduling process.
First, I’ll discuss the
pattern, in which you use session beans to access
entity beans. This access method is
used instead of allowing direct access to entity beans, and is key to
a sound strategy in building enterprise applications.
I’ll also outline the problems and penalties
associated with this approach, giving you the information you need to
make good decisions in your own applications. This pattern goes hand
in hand with the manager component discussed in Chapter 6 when working with directory servers.
I’ll illustrate the pattern with a simple example,
an OfficeManager session bean.
From there, I’ll move on to slightly more complex
session beans. You’ll see how a single session bean
can perform operations on multiple beans and on other Java
components. You’ll build a
UserManager component, which will administer
users, and will operate upon the User entity bean as well as the
LDAPManager directory server component. This should give you an idea of how to handle ...