WebLogic: The Definitive Guide

Chapter 10. Using EJBs

Enterprise JavaBeans (EJBs) are reusable server-side Java components that encapsulate the business logic of a distributed application. All EJBs are created and managed at runtime by an EJB container, which provides essential system-level services such as support for transactions, security, persistence, and concurrency. WebLogic mediates all client invocations to the enterprise bean through the EJB container.

In this chapter, you will learn about building, deploying, and optimizing EJBs within WebLogic. To do this, you also will see how the XML deployment descriptors help configure the various services provided by the EJB container. In fact, the XML descriptors provide vital information on assembly and deployment, and also determine how the container manages the EJB instances at runtime. The standard XML descriptor contains information on deployment, the abstract schema model, security restrictions, and transaction settings for the EJB component. The WebLogic-specific deployment descriptors allow you to configure the main topics covered by this chapter — namely pooling, EJB concurrency, automatic EJB persistence, transaction, failover and clustering behavior, and life-cycle optimizations.

Any EJB implementation requires several Java classes and a number of XML descriptor files. Creating, synchronizing, and maintaining these configuration settings have traditionally been quite a burden on the developer. WebLogic provides several tools to remove this hardship. ...