Enterprise JavaBeans 3.0, 5th Edition

Chapter WORKBOOK 3. Exercises for Chapter 5

Chapter 5 of the EJB book walked you through all of the details for deploying, creating, and interacting with the EntityManager interface. This chapter uses the same Cabin entity bean introduced in Chapter 4 to illustrate the concepts and APIs discussed in Chapter 5. You will see examples of:

• The merge( ), flush( ), and refresh( ) operations in action

• An explanation of FlushModeType

• The differences between a transaction-only and an extended persistence context

• Using Java Persistence in a standalone Java application

Exercise 5.1 walks you through the first three bullets, and Exercise 5.2 shows you how to use persistence outside of the application server.

Exercise 5.1: Interacting with EntityManager

This exercise has four different clients to build and run against the JBoss application server:

Client_1.java

This client demonstrates what happens when you use the EntityManager.merge( ) operation. It interacts with the TravelAgent EJB.

Client_2.java

This client demonstrates the difference between a transaction-only and an extended persistence context. The TransactionPersistenceContext EJB injects and uses a transaction-scoped entity manager. The ExtendedPersistenceContext EJB injects and uses an extended entity manager.

Client_3.java

This client demonstrates how FlushModeType affects your application—specifically, when updates are synchronized with the database.

These clients must be executed in order; Client_1 creates a Cabin entity that is used by ...