EJB 3.0 JNDI lookup results in Classcast Exception

Question

Hello everybody,
I�m experiencing a strange problem when I want to retrieve a stateless session bean from a POJO in my enterprise app. I am using EJB 3.0, running on Glassfish build 33 and JDK 1.5.
I have successfully deployed my ear file which has the EJB.jar and the war file in it. I�m using JSF 1.2 in the web app and I am able to use all session beans using the injection annotation in my managed beans (this is how it is supposed to be according to the spec.). However, I now need to acces a stateless session bean from a POJO (non-managed or backing bean) which resides also in the war file. I�m using the following code to retrieve the session bean:
(where IMySessionBean = remote interface and MySessionBean is the implementation)
try {
ic = new InitialContext();
MySessionBean mybean = (MySessionBean )ic.lookup("env/IMySessionBean");
When casting the object from the lookup into MySessionBean I get a classcast Exception. However, I can see the session bean using the JNDI browser that comes with Glassfish and it�s deployed and available. If mybean is of type Object, I see that the lookup method returns a wrapper of my session bean.
Here�s what the stacktrace says:
java.lang.ClassCastException: com.myproject.ejb.interfaces._IMySessionBean_Wrapper
     at ...
Do I miss something here and there�s more required to obtain a reference to the session bean? I�m pretty much stuck here and any help is greastly appreciated!
Thanks in advance!
Cheers,
Joerg

Answer 1

Hi Joerg,
In the session bean client view, the bean implementation class is never used. The client
only interacts with the local or remote interface.
Regarding the lookup, the more portable approach is to
lookup the ejb reference through the component environment of the web application
rather than doing a direct global lookup. If you have already defined any ejb reference
injections somewhere in the web app, you can look up the same dependencies via
java:comp/env. For example, if your managed bean has the following @EJB annotation :
@EJB(name="mybeanref") IMySessionBean beanRef;
You can look up the same underlying dependency in your utility class :
IMySessionBean beanRef = (IMySessionBean) new InitialContext().lookup
("java:comp/env/mybeanref");
Note that the portion of the lookup string after java:comp/env/ comes from the name() attribute
of @EJB. @EJB name() has the same semantics as the ejb-ref-name in the deployment
descriptor. You can find more info on these topics in our EJB FAQ :
https://glassfish.dev.java.net/javaee5/ejb/EJB_FAQ.html