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List:       openjms-developer
Subject:    [openjms-developer] [ openjms-Bugs-831469 ] ClassCastException when using MDBs in Sun ONE AS7
From:       "SourceForge.net" <noreply () sourceforge ! net>
Date:       2003-11-18 20:06:29
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Bugs item #831469, was opened at 2003-10-27 19:26
Message generated for change (Comment added) made by scubabear68
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=474136&aid=831469&group_id=54559

Category: client
Group: v0.7.6-rc1
Status: Open
Resolution: None
Priority: 5
Submitted By: Bo Min Jiang (jiangb)
Assigned to: Jim Alateras (jalateras)
Summary: ClassCastException when using MDBs in Sun ONE AS7

Initial Comment:
I am running Sun ONE Application Server 7 with OpenJMS 
as the JMS provider, and have run into a problem with 
Message Driven Beans.

In the onMessage method of class 
org.exolab.jms.client.JmsConnectionConsumer, a 
ServerSession object is being retrieved from a server 
session pool, and is then cast into a JmsServerSession 
object.  However, the server session pool is an 
application server specific object (for Sun ONE AS7, it's 
implemented by class 
com.iplanet.ias.ejb.containers.IASServerSessionImpl), 
and cannot necessarily be cast into an a 
JmsServerSession object - a ClassCastException occurs 
as a result.  Unfortunately, Sun ONE does not allow me 
to specify a different implementation of the 
ServerSession interface.

Is there a workaround for the problem described?  I need 
to use Sun ONE AS7, and am curious if a similar problem 
exists when using other application servers.

----------------------------------------------------------------------

Comment By: Mike Spille (scubabear68)
Date: 2003-11-18 15:06

Message:
Logged In: YES 
user_id=583085

I don't have time for a fully integrated diff, but the essence 
of the fix for this is:

JmsSession.run():

    public void run() {
        if (connConsumer == null) {
            return;
        }
        Message msg;
        while ((msg = connConsumer.nextMessage()) != null) {
            execute (msg);
        }
        connConsumer = null;
   }


JmsConnectionConsumer:
abstract class JmsConnectionConsumer
    implements ConnectionConsumer, MessageListener 
{
    private Message activeMessage;
    private static int objCount = 0;

    /**
     * This constructor simply manaages the server session 
pool and the 
     * the maximum number of messages that can be loaded 
on any one server
     * session.
     * 
     * @param       pool            the server session pool
     * @param       maxMessages     max number of messages 
it can send to down
     *                              a server session object at any one 
time.
     */
    JmsConnectionConsumer(ServerSessionPool pool, int 
maxMessages) 
    {
        pool_ = pool;
        maxMessages_ = (maxMessages > 0) ? maxMessages : 
1;
        objCount++;
    }

    /**
     * Return a reference ot the server session pool instance 
use by this
     * object
     * <p>
     * If the object is not set or there is any other issue throw 
the 
     * JMSException exception.
     *
     * @return      ServerSessionPool
     * @exception   JMSException
     */
    public ServerSessionPool getServerSessionPool() 
        throws JMSException
    {
        return pool_;
    }
 
    /** 
     * Since a provider may allocate some resources on behalf 
of a 
     * ConnectionConsumer outside the JVM, clients should 
close them when
     * they are not needed. Relying on garbage collection to 
eventually 
     * reclaim these resources may not be timely enough.
     *  
     * @exception JMSException if a JMS fails to release 
resources on
     *                         behalf of ConnectionConsumer or it 
fails
     *                         to close the connection consumer.
     */
    public void close() 
        throws JMSException 
    {
        pool_ = null;
    }

    /**
     * Impmentation of MessageListener.onMessage, which will 
receive
     * messages from the server. In this most simply case it 
actually 
     * loads each individual message into a server session and 
calls 
     * the start method.
     * <p>
     * If this methods gets an error then it will send an error 
message
     * to the logger and return successful
     *
     * @param       message         message send back by the 
server.
     */
    public void onMessage(Message message)
    {
        try
        {
            // not very sophisticated at this point. Simply get a 
server
            // session put the message in it and start it.
            /* MWS - This looks incorrect.  The App Server 
implements the ServerSession pool object, therefore it's 
wrong for us to assume it's one of ours
            getSession().acknowledgeMessage(message);
            JmsServerSession local_session = (JmsServerSession)
pool_.getServerSession();
            local_session.addMessage(message);
            local_session.start();
            */
			activeMessage = message;
            ServerSession servSession = pool_.getServerSession
();
            JmsSession session = (JmsSession)
servSession.getSession();
            session.setConnectionConsumer (this);
            servSession.start();
        }
        catch (Exception exception)
        {
        }
    }

    Message
    nextMessage ()
    {
        Message msg = activeMessage;
        activeMessage = null;
        return (msg);
    }

    /**
     * Abstract mathod that returns the proxy to the server 
side session attached
     * to this object
     *
     * @return      Session
     */
    abstract JmsSession getSession();

    /**
     * Return the maximum number of messages that can be 
loaded down any one
     * server session
     *
     * @return      int
     */
    int getMaxMessages()
    {
        return maxMessages_;
    }

    /**
     * This is a reference to the server session pool, which is 
used to deliver
     * messages to the actual processing client.
     */
    private ServerSessionPool pool_ = null;

    /**
     * This attribute describes the maximum number of 
messages that can be 
     * loaded on a server session at any one time.
     */
    private int maxMessages_ = 1;
}



----------------------------------------------------------------------

Comment By: Tim Anderson (tanderson)
Date: 2003-10-27 19:51

Message:
Logged In: YES 
user_id=557161

OpenJMS's support for MDB's is untested - if you have the 
time, any contribution with respect to this would be much 
appreciated.

----------------------------------------------------------------------

You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=474136&aid=831469&group_id=54559


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