How To Expose And Inject A POJO ...Into An EJB 3

A POJO:

public class CustomResource{

    public final static String JNDI_NAME = "theName";

    public void doSomething(){

        System.out.println("#Done !");

    }

}

can be easily exposed (=bound to JNDI) with a singleton bean:

@Startup

@Singleton

public class ResourceBinder {

    @PostConstruct

    public void bindResources(){

        try {

            Context context = new InitialContext();

            context.rebind(CustomResource.JNDI_NAME, new CustomResource());

            System.out.println("Resource bound...");

            System.out.println(" " + context.lookup(CustomResource.JNDI_NAME));

        } catch (NamingException ex) {

            throw new IllegalStateException("Cannot bind resource " +ex,ex);

        }

    }

} 

...and injected into a Stateless, Stateful, Singleton Bean or other resources like e.g. Servlets, Backing Beans etc:

@Singleton

@Startup

@DependsOn("ResourceBinder")

public class CustomResourceClient {

    @Resource(mappedName=CustomResource.JNDI_NAME)

    private CustomResource resource;

    @PostConstruct

    public void invokeResource(){

        this.resource.doSomething();

        System.out.println("----Resource invoked");

    }

}

 You should see the following output in the log files (tested with Glassfish v3b70):

INFO: Portable JNDI names for EJB CustomResourceClient : [java:global/ResourceBinder/CustomResourceClient!com.abien.patterns.kitchensink.resourcebinder.CustomResourceClient, java:global/ResourceBinder/CustomResourceClient]

INFO: Portable JNDI names for EJB ResourceBinder : [java:global/ResourceBinder/ResourceBinder, java:global/ResourceBinder/ResourceBinder!com.abien.patterns.kitchensink.resourcebinder.ResourceBinder]

INFO: Resource bound...

INFO:  com.abien.patterns.kitchensink.resourcebinder.CustomResource@50058560

INFO: #Done !

INFO: ----Resource invoked 

The ResourceBinder project was tested with NetBeans 6.8beta and Glassfish v3b70. It was pushed into: http://kenai.com/projects/javaee-patterns/.  Closing remarks:

1. It is easier and better to declare a POJO as a Session Bean. You gain a lot with almost no trade-offs.
2. You should be careful with the concurrency. Such an exposed POJO will be accessed by several threads / transactions concurrently.
3. You easily inject POJOs with interceptors as well.
4. You should never use System.out.println on the server in production, because of:
    public void println(String x) {
   synchronized (this) {
      print(x);
      newLine();
   }
       }

 [See "Resource Binder" pattern, page 243,  in "Real World Java EE Patterns Rethinking Best Practices" book for more in-depth discussion]