NamingException: Could not dereference object - EJB 3.0 workbook ex05-2

[Jack Bush]

Hi Everyone,

I have stucked on workbook ex05_2 that makes comparison between using the same entity bean in TransactionPersistenceContext & ExtendedPersistenceContext. Anyhow, the following error occurred when trying to access either of these contexts:

javax.naming.NamingException: Could not dereference object [Root exception is java.lang.reflect.UndeclaredThrowableException]
at org.jnp.interfaces.NamingContext.getObjectInstanceWrapFailure(NamingContext.java:1150)
at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:705)
at org.jnp.interfaces.NamingContext.lookup(NamingContext.java:587)
at javax.naming.InitialContext.lookup(InitialContext.java:392)
at client.Main.main(Main.java:33)
Caused by: java.lang.reflect.UndeclaredThrowableException
at $Proxy1.createProxy(Unknown Source)
at org.jboss.ejb3.JndiProxyFactory.getObjectInstance(JndiProxyFactory.java:52)
at javax.naming.spi.NamingManager.getObjectInstance(NamingManager.java:304)
at org.jnp.interfaces.NamingContext.getObjectInstance(NamingContext.java:1125)
at org.jnp.interfaces.NamingContext.getObjectInstanceWrapFailure(NamingContext.java:1142)
... 4 more

This message make sense considering the jndi listing as follows:

+- ExtendedPersistenceContextBean (class: org.jnp.interfaces.NamingContext)
| +- remote (class: java.lang.Object)
| +- remoteStatefulProxyFactory (proxy: $Proxy76 implements interface org.jboss.ejb3.ProxyFactory)
+- TravelAgentBean (class: org.jnp.interfaces.NamingContext)
| +- remote (proxy: $Proxy81 implements interface travelagent.TravelAgentRemote,interface org.jboss.ejb3.JBossProxy,interface javax.ejb.EJBObject)
+- TransactionPersistenceContextBean (class: org.jnp.interfaces.NamingContext)
| +- remote (class: java.lang.Object)
| +- remoteStatefulProxyFactory (proxy: $Proxy76 implements interface org.jboss.ejb3.ProxyFactory)

To call TravelAgentRemote interface, use jndiContext.lookup(" TravelAgentBean/remote"). However, it appears that
I would not get anything by calling either jndiContext.lookup(" TransactionPersistenceContextBean/remote") or jndiContext.lookup(" ExtendedPersistenceContextBean/remote") according to the above jndi table.

The client code are as follows:

try 
{
            Context jndiContext = getInitialContext();
            Object ref = jndiContext.lookup("TravelAgentBean/remote");
            TravelAgentRemote dao = (TravelAgentRemote)ref;
 
            ref = jndiContext.lookup("[B]TransactionPersistenceContextBean/remote[/B]
");
            TransactionPersistenceContextRemote txBean = (TransactionPersistenceContextRemote)ref;
 
    Cabin fetchedCabin = dao.findCabin(1);
            int oldBedCount = fetchedCabin.getBedCount();
 
    System.out.println("Set up transaction persistence context stateful bean");
    txBean.setCabin(1);
    txBean.updateBedCount(5);
 
            ref = jndiContext.lookup("
[B]ExtendedPersistenceContextBean/remote[/B]");
            ExtendedPersistenceContextRemote extendedBean = (ExtendedPersistenceContextRemote)ref;
 
          extendedBean.setCabin(1);
    extendedBean.updateBedCount(5);
....

This exercise does not work as delivered on the command prompt.

I am running Netbeans 5.5, JBoss 4.0.5GA & JDK1.6.0 on Windows XP platform.

The workbook is from EJB 3.0 by Bill Burke.

Any assistance would be greatly appreciated.

Thanks,

Henry

[Jack Bush]

Hi,

I managed to overcome this issue with the following syntax when using Sun System Java Application Server PE 9.0:

ref = jndiContext.lookup("travelagent.TransactionPersistenceContextRemote");
ref = jndiContext.lookup("travelagent.ExtendedPersistenceContextRemote");

The Client output from Netbeans is:

no cabin should be null: null
Master Suite
1
1
3
Updating detached cabin instance with new bed count of 4
Finding cabin to see it has been updated with a merge() on server
new bed count is: 4
Set up transaction persistence context stateful bean
Cabin bed count will still be 4: 4
Set up extended persistence context stateful bean
Cabin bed count will be 5: 5

However, I still could not find a solution when running in JBoss AS 4.0.5.

Thanks,

Henry

[Jack Bush]

Hi All,

Could someone please help me with this issue on the JBoss platform?

I still could not identify what the problem for so many weeks.

Thanks,

Henry

[Jaikiran Pai]

You are having problems looking up the TransactionPersistenceContextBean/remote and the other bean on JBoss? Can you post the code for this bean? Especially the annotations on each of these beans.

[Jack Bush]

Hi Jaikiran,

Here are the codes as requested:

package travelagent;
 
import javax.ejb.Remote;
 
import domain.Cabin;
 
@Remote
public interface TravelAgentRemote
{
   public void createCabin(Cabin cabin);
   public Cabin findCabin(int pKey);
   public void updateCabin(Cabin cabin);
   public void flushModeExample();
}

package travelagent;
 
import javax.ejb.Stateless;
import javax.ejb.Remote;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceUnit;
import javax.persistence.FlushModeType;
 
import domain.Cabin; 
 
@Stateless
@Remote(TravelAgentRemote.class)
public class TravelAgentBean implements TravelAgentRemote
{
   @PersistenceUnit(unitName="titan") private EntityManagerFactory factory;
   @PersistenceContext(unitName="titan") private EntityManager manager;
    
   public void createCabin(Cabin cabin)
   {
      manager.persist(cabin);
   }
 
   public Cabin findCabin(int pKey)
   {
      return manager.find(Cabin.class, pKey);
   }
   
   public void updateCabin(Cabin cabin)
   {
      manager.merge(cabin);
   }
   
   public void flushModeExample()
   {
      EntityManager createdManager = factory.createEntityManager();
        
      try
      {
         Cabin newCabin2 = new Cabin();
         newCabin2.setId(2);
         newCabin2.setName("Another Cabin");
         newCabin2.setBedCount(1);
         createdManager.persist(newCabin2);
 
         Cabin cabin2 = manager.find(Cabin.class, 2);
         if (cabin2 != null) 
         {
            throw new RuntimeException("newCabin2 should not be flushed yet");
         }
 
         Cabin cabin1 = (Cabin)createdManager.createQuery("FROM Cabin c WHERE c.id = 1").getSingleResult();
            
         cabin2 = manager.find(Cabin.class, 2);
         if (cabin2 == null)
         {
            throw new RuntimeException("newCabin2 should be flushed now");
         }
 
         createdManager.setFlushMode(FlushModeType.COMMIT);
         newCabin2.setBedCount(99);
 
         cabin1 = (Cabin)createdManager.createQuery("FROM Cabin c WHERE c.id = 1").getSingleResult();
 
         manager.refresh(cabin2);
         if (cabin2.getBedCount() == 99) 
         {
            throw new RuntimeException("should not be 99 yet with COMMIT and a query");
         }
 
         createdManager.flush();
 
         manager.refresh(cabin2);
         if (cabin2.getBedCount() != 99)
         {
            throw new RuntimeException("should be 99 yet with a flush");
         }
      }
      finally
      {
         createdManager.close();
      }
   }
}

package travelagent;
 
import javax.ejb.Remote;
 
import domain.Cabin;
 
@Remote
public interface TransactionPersistenceContextRemote
{
    public void setCabin(int pk);
    public void updateBedCount(int newBedCount);
    public void remove();
}

package travelagent;
 
import javax.ejb.Stateful;
import javax.ejb.Remote;
import javax.ejb.Remove;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceContextType;
 
import domain.Cabin; 
 
@Stateful
@Remote(TransactionPersistenceContextRemote.class)
public class TransactionPersistenceContextBean implements TransactionPersistenceContextRemote
{
    @PersistenceContext(unitName="titan", type=PersistenceContextType.TRANSACTION)
    private EntityManager manager;
 
    private Cabin cabin;
 
    public void setCabin(int pk)
    {
       cabin = manager.find(Cabin.class, pk);
    }
 
    public void updateBedCount(int newBedCount)
    {
       cabin.setBedCount(newBedCount);
    }
 
    @Remove
    public void remove()
    {
    }
}

package travelagent;
 
import javax.ejb.Remote;
 
import domain.Cabin;
 
@Remote
public interface ExtendedPersistenceContextRemote
{
    public void setCabin(int pk);
    public void updateBedCount(int newBedCount);
    public void remove();
}

package travelagent;
 
import javax.ejb.Stateful;
import javax.ejb.Remote;
import javax.ejb.Remove;
import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.PersistenceContextType;
 
import domain.Cabin; 
 
@Stateful
@Remote(ExtendedPersistenceContextRemote.class)
public class ExtendedPersistenceContextBean implements ExtendedPersistenceContextRemote
{
    @PersistenceContext(unitName="titan", type=PersistenceContextType.EXTENDED)
    private EntityManager manager;
 
    private Cabin cabin;
 
    public void setCabin(int pk)
    {
cabin = manager.find(Cabin.class, pk);
    }
 
    public void updateBedCount(int newBedCount)
    {
cabin.setBedCount(newBedCount);
    }
 
    @Remove
    public void remove()
    {
    }
}

I did not have any problem running them using SJAS PE 9.0 by modifying the JNDI lookup to use "travelagent.TransactionPersistenceContextRemote" as opposed to "TransactionPersistenceContextBean/remote".

The Client code looks like this:

package amy1client;
 
import travelagent.TravelAgentRemote;
import domain.Cabin;
import travelagent.ExtendedPersistenceContextRemote;
import travelagent.TransactionPersistenceContextRemote;
 
import javax.naming.InitialContext;
import javax.naming.Context;
import javax.naming.NamingException;
 
import javax.rmi.PortableRemoteObject;
 
public class Main {
    
    public static void main(String[] args) {
        
        try 
        {
            Context jndiContext = getInitialContext();
            Object ref = jndiContext.lookup("TravelAgentBean/remote");
            TravelAgentRemote dao = (TravelAgentRemote)ref;
            
            Cabin noCabin = dao.findCabin(1);
            System.out.println("no cabin should be null: " + noCabin);
 
            Cabin cabin_1 = new Cabin();
            cabin_1.setId(1);
            cabin_1.setName("Master Suite");
            cabin_1.setDeckLevel(1);
            cabin_1.setShipId(1);
            cabin_1.setBedCount(3);
 
            dao.createCabin(cabin_1);
 
            Cabin cabin_2 = dao.findCabin(1);
            System.out.println(cabin_2.getName());
            System.out.println(cabin_2.getDeckLevel());
            System.out.println(cabin_2.getShipId());
            System.out.println(cabin_2.getBedCount());
 
    System.out.println("Updating detached cabin instance with new bed count of 4");
    cabin_2.setBedCount(4);
    dao.updateCabin(cabin_2);
 
    System.out.println("Finding cabin to see it has been updated with a merge() on server");
            Cabin cabin_3 = dao.findCabin(1);
    System.out.println("new bed count is: " + cabin_3.getBedCount());
        } 
        catch (javax.naming.NamingException ne)
        {
    ne.printStackTrace();
}
    }
    
    public static Context getInitialContext() 
        throws javax.naming.NamingException 
    {
        return new javax.naming.InitialContext();
    }
    
}

package amy2client;
 
import travelagent.TravelAgentRemote;
import domain.Cabin;
import travelagent.ExtendedPersistenceContextRemote;
import travelagent.TransactionPersistenceContextRemote;
 
import javax.naming.InitialContext;
import javax.naming.Context;
import javax.naming.NamingException;
 
import javax.rmi.PortableRemoteObject;
 
public class Main {
    
    public static void main(String[] args) {
        
        try 
        {
            Context jndiContext = getInitialContext();
            Object ref = jndiContext.lookup("TravelAgentBean/remote");
            TravelAgentRemote dao = (TravelAgentRemote)ref;
            
            ref = jndiContext.lookup("TransactionPersistenceContextBean/remote");
            TransactionPersistenceContextRemote txBean = (TransactionPersistenceContextRemote)ref;
 
    Cabin fetchedCabin = dao.findCabin(1);
            int oldBedCount = fetchedCabin.getBedCount();
 
    System.out.println("Set up transaction persistence context stateful bean");
    txBean.setCabin(1);
    txBean.updateBedCount(5);
 
    fetchedCabin = dao.findCabin(1);
    System.out.println("Cabin bed count will still be " + oldBedCount + ": " + fetchedCabin.getBedCount());
 
    System.out.println("Set up extended persistence context stateful bean");
 
            ref = jndiContext.lookup("ExtendedPersistenceContextBean/remote");
            ExtendedPersistenceContextRemote extendedBean = (ExtendedPersistenceContextRemote)ref;
 
    extendedBean.setCabin(1);
    extendedBean.updateBedCount(5);
 
    fetchedCabin = dao.findCabin(1);
    System.out.println("Cabin bed count will be 5: " + fetchedCabin.getBedCount());
 
    // cleanup
    txBean.remove();
    extendedBean.remove();                       
 
        } 
        catch (javax.naming.NamingException ne)
        {
    ne.printStackTrace();
}
    }
    
    public static Context getInitialContext() 
        throws javax.naming.NamingException 
    {
        return new javax.naming.InitialContext();
    }
}

The main() method in amy1client runs first to setup the Cabin table prior to running amy2client.

Here is the detail on JMX-Console:

jboss.j2ee
jar=amy.jar,name=ExtendedPersistenceContextBean,service=EJB3
jar=amy.jar,name=TransactionPersistenceContextBean,service=EJB3
jar=amy.jar,name=TravelAgentBean,service=EJB3
module=amy.jar,service=EJB3

Jndi View
ExtendedPersistenceContextBean (class: org.jnp.interfaces.NamingContext)
| +- remote (class: java.lang.Object)
| +- remoteStatefulProxyFactory (proxy: $Proxy74 implements interface org.jboss.ejb3.ProxyFactory)
+- JBossClient (class: org.jnp.interfaces.NamingContext)
+- UILXAConnectionFactory[link -> XAConnectionFactory] (class: javax.naming.LinkRef)
+- UIL2XAConnectionFactory[link -> XAConnectionFactory] (class: javax.naming.LinkRef)
+- queue (class: org.jnp.interfaces.NamingContext)
| +- A (class: org.jboss.mq.SpyQueue)
| +- testQueue (class: org.jboss.mq.SpyQueue)
| +- ex (class: org.jboss.mq.SpyQueue)
| +- DLQ (class: org.jboss.mq.SpyQueue)
| +- D (class: org.jboss.mq.SpyQueue)
| +- C (class: org.jboss.mq.SpyQueue)
| +- B (class: org.jboss.mq.SpyQueue)
+- topic (class: org.jnp.interfaces.NamingContext)
| +- testDurableTopic (class: org.jboss.mq.SpyTopic)
| +- testTopic (class: org.jboss.mq.SpyTopic)
| +- securedTopic (class: org.jboss.mq.SpyTopic)
+- amy2-Client (class: org.jnp.interfaces.NamingContext)
+- console (class: org.jnp.interfaces.NamingContext)
| +- PluginManager (proxy: $Proxy46 implements interface org.jboss.console.manager.PluginManagerMBean)
+- UIL2ConnectionFactory[link -> ConnectionFactory] (class: javax.naming.LinkRef)
+- HiLoKeyGeneratorFactory (class: org.jboss.ejb.plugins.keygenerator.hilo.HiLoKeyGeneratorFactory)
+- TravelAgentBean (class: org.jnp.interfaces.NamingContext)
| +- remote (proxy: $Proxy88 implements interface travelagent.TravelAgentRemote,interface org.jboss.ejb3.JBossProxy,interface javax.ejb.EJBObject)
+- UILConnectionFactory[link -> ConnectionFactory] (class: javax.naming.LinkRef)
+- TransactionPersistenceContextBean (class: org.jnp.interfaces.NamingContext)
| +- remote (class: java.lang.Object)
| +- remoteStatefulProxyFactory (proxy: $Proxy74 implements interface org.jboss.ejb3.ProxyFactory)

I have been trying to setup these beans to run as local just to see whether it make any difference. However, it has been slow since I am still learning to ropes of EJB 3.0 Session Beans.

Thanks again,

Henry

[Jaikiran Pai]

I am running Netbeans 5.5, JBoss 4.0.5GA & JDK1.6.0 on Windows XP platform.

Hmmmm.... I shouldn't have ignored this earlier Looks like this is an issue with JDK1.6 with JBoss. Here's a similar issue. The solution for this appears to be to use JDK5 instead of JDK6

[Jack Bush]

Hi Jaikiran,

The recommendation from http://jboss.com/index.html?module=bb&op=viewtopic&t=98072&view=previous was correct.

By only running the Client program (EJB3ex512-Client)using SDK 1.5 solved this issue.

All session beans and other clients are still using SDK 1.6 without a problem.

Thanks again,

Henry