Chapter 5. Enterprise Applications with EJB3 Services

EJB3 (Enterprise Java Bean 3.0) provides the core component model for Java EE 5 applications. An EJB3 bean is a managed component that is automatically wired to take advantage of all services the Java EE 5 server container provides, such as transaction, security, persistence, naming, dependency injection, etc. The managed component allows developers to focus on the business logic, and leave the cross-cutting concerns to the container as configurations. As an application developer, you need not create or destroy the components yourself. You only need to ask for an EJB3 bean from the Java EE container by its name, and then you can call its methods with all configured container services applied. You can get access to an EJB3 bean from either inside or outside of the Java EE container.

JBoss Enterprise Application Platform 5 supports EJB3 out of the box. Note that JBoss Enterprise Application Platform 4.2 is a J2EE server, so it does not support the full EJB3 feature set.

The details of the EJB3 component programming model is beyond the scope of this guide. Most EJB3 interfaces and annotations are part of the Java EE 5 standard and hence they are the same for all Java EE 5 compliant application servers. Interested readers should refer to the EJB3 specification or numerous EJB3 books to learn more about EJB3 programming.

In this chapter, we only cover EJB3 configuration issues that are specific to the JBoss Enterprise Application Platform. For instance, we discuss the JNDI naming conventions for EJB3 components inside the JBoss Enterprise Application Platform, the optional configurations for the Hibernate persistence engine for entity beans, as well as custom options in the JBoss EJB3 deployer.

@Local
public interface MyBeanInt {
  public String doSomething (String para1, int para2);
}

@Stateless
public class MyBean implements MyBeanInt {

  public String doSomething (String para1, int para2) {
    ... implement the logic ...
  } 
  
}    

try {
  InitialContext ctx = new InitialContext();
  MyBeanInt bean = (MyBeanInt) ctx.lookup("myapp/MyBean/local");
} catch (Exception e) {
  e.printStackTrace ();
}

... ...

String result = bean.doSomething("have fun", 1);

... ...

@Stateless
@LocalBinding (jndiBinding="MyService/MyOwnName")
public class MyBean implements MyBeanInt {

  public String doSomething (String para1, int para2) {
    ... implement the logic ...
  } 
  
}