Very simple EJB 3.0 MDB but I get NullPointerException

Question

I tried to create a very simple EJB 3.0 Message Driven Bean in JDeveloper 10.1.3.2 as follows:
Message Driven Bean Class:
import javax.ejb.MessageDriven;
import javax.jms.Message;
import javax.jms.MessageListener;
@MessageDriven(mappedName="MDBQueue")
public class MDB implements MessageListener {
public void onMessage(Message message) {
System.out.println("Got message!");
Application Client:
import javax.annotation.Resource;
import javax.jms.*;
public class MDBAppClient {
@Resource(mappedName="MDBQueueConnectionFactory")
private static QueueConnectionFactory queueCF;
@Resource(mappedName="MDBQueue")
private static Queue mdbQueue;
public static void main(String args[]) {
try {
QueueConnection queueCon = queueCF.createQueueConnection();
QueueSession queueSession = queueCon.createQueueSession
(false, Session.AUTO_ACKNOWLEDGE);
QueueSender queueSender = queueSession.createSender(null);
TextMessage msg = queueSession.createTextMessage("hello");
queueSender.send(mdbQueue, msg);
System.out.println("Sent message to MDB");
queueCon.close();
} catch(Exception e) {
e.printStackTrace();
But I get the following error:
java.lang.NullPointerException
     at model.MDBAppClient.main(MDBAppClient.java:17)
I read similar problem in the this thread:
Re: message driven bean on ejb 3.0 does not work
some one said that the version in ejb-jar.xml must be changed from 2.1 to 3.0
but in this case there is no ejb-jar.xml.
( I have other cases with ejb-jar.xml file but I can't change the version in ejb-jar.xml)
the version in web.xml is 2.4 but it not accept any value except 2.4 and an error occur when I tried to change it to 3.0
please can you tell me why I get NullPointerException and how can I allow EJB 3.0 MDB and JMS to work in JDeveloper

Answer 1

Note that you can't run MDBs in the embedded OC4J in JDeveloper - try deploying to a stand-alone install of OC4J and see if it works there.