[CONF] OpenEJB 3.0.x documentation: Local Client Injection (page created)

Mon, 15 Jun 2009 15:31:36 -0700

Page Created : OPENEJBx30 : Local Client Injection

Local Client Injection has been created by David Blevins (Jun 15, 2009).

Content:
OpenEJB 3.1.1 or later required

The @LocalClient annotation (org.apache.openejb.api.LocalClient) is an innovation that crosses concepts of an Java EE Application Client with a plain Java SE client. This particular annotation is focused on clients of an Embeddable EJB container, i.e. local clients. There is another annotation in development called @RemoteClient that will be focused on remote clients; clients running outside the vm the container runs.

Any clients annotated with @LocalClient will be scanned at deployment time for usage of injection-related annotations. The references in the @LocalClient will be processed with the application just as if the class was a Java EE Application Client module, but with a few slight differences:

  1. Declaring field/method injection points as 'static' is not required
  2. References to EntityManagers via @PersistenceContext are allowed
  3. References to local business interfaces via @EJB is allowed
  4. References to UserTransaction via @Resource is allowed

As well since this is not a heavyweight Java EE Application Client, you are not required to use any special packaging or command-line parameters to run the client. Your client can be a Unit Test or any plain java code that needs to pull objects from the Embedded EJB container. Classes with @LocalClient can be placed in a Client module or an EJB module. A given module may have as many classes annotated with @LocalClient as it wishes.

Injection

The injection occurs via acquiring a LocalInitialContext via the LocalInitialContextFactory and calling bind("inject", instance) passing in the instantiated local client object:

@LocalClient
public class MoviesTest extends TestCase {

    @EJB
    private Movies movies;

    @Resource
    private UserTransaction userTransaction;

    @PersistenceContext
    private EntityManager entityManager;

    public void setUp() throws Exception {
        Properties p = new Properties();
        p.put(Context.INITIAL_CONTEXT_FACTORY, "org.apache.openejb.client.LocalInitialContextFactory");
        InitialContext initialContext = new InitialContext(p);
        initialContext.bind("inject", this);
    }

    //... other test methods
}

Discovery

All EJB modules are scanned for @LocalClient classes, even if those EJB Modules are inside .war files as with the Collapsed EAR. As well any modules that contain a META-INF/application-client.xml file will be scanned for @LocalClient classes.

If you see the following error message and are absolutely sure the module containing your @LocalClient class is being properly identified as an EJB module or a Client module, than it is possible you are seeing some classloading issues. We have not seen this in Intellij or Maven, but we have seen it randomly in Eclipse.

javax.naming.NamingException: Unable to find injection meta-data for org.superbiz.MyClient. Ensure that class was annotated with @org.apache.openejb.api.LocalClient and was successfully discovered and deployed.

If you encounter this try setting this openejb-specific boot flag so that annotations will be treated specially and always loaded by the parent classloader

openejb.tempclassloader.skip=annotations

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