We gave an overview of the EJB 3 architecture and its relationship to the multi-layer Java EE architecture. EJB technology applies to the business processing and persistence layers of the multi-layer model. There are three main artifacts a business application using EJB technology will develop: session-beans, message-driven beans, and entities.

These artifacts are deployed to an EJB container which provides a number of services. We had a brief look at some of these services. In particular we saw that a separate service, the Java Persistence API, is provided for persisting entities.

Finally we saw how to get started with Sun's open-source GlassFish EJB 3 container. All the examples which follow in this book have been deployed and run on GlassFish.

In the following chapter we will look at developing the EJB component which handles business processing, namely session beans.