In the final part of this book, we explore some of the issues you are bound to come across while using EJB 3 in the real world. These advanced topics are primarily geared toward migration, system integration, and interoperability.
If you are already using EJB 2 and are looking at EJB 3, chapter 14 is critically important to you. The chapter discusses migrating from EJB 2 to EJB 3 in great detail. We first see how EJB 2 and EJB 3 can coexist in the short run if necessary. We then look at migrating EJB 2 session beans and MDBs to EJB 3, followed by migrating applications using EJB 2 CMP entity beans, JDBC DAOs, and proprietary O/R frameworks such as Hibernate/TopLink to JPA.
In chapter 15, we move on to the red-hot topic of enabling interoperability through web services. In this chapter we show you how EJB 3 and web services can help integrate Java EE with other disparate technologies such as Microsoft .NET. You’ll learn how EJB 3 and web services relate to each other and how stateless session beans can be exposed as web services utilizing Java XML Web Service (JAX-WS) 2.0 support.
Finally, we tackle what very well might be the most intriguing topic of the book: Spring and EJB 3. EJB 3 and the Spring framework are often viewed as competing frameworks. In chapter 16, we present a slightly different take on things. We show you how EJB 3 opens the door to the possibility of integrating with Spring in several ways and combining the power of both of these technologies.