[jmscts-developer] [ jmscts-Bugs-881228 ] org.exolab.jmscts.test.connection.ListenerTest

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Bugs item #881228, was opened at 2004-01-21 08:42
Message generated for change (Comment added) made by dnb7
You can respond by visiting: 
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Category: None
Group: v0.5-b1
Status: Open
Resolution: None
Priority: 5
Submitted By: Daniel Bauer (dnb7)
Assigned to: Nobody/Anonymous (nobody)
Summary: org.exolab.jmscts.test.connection.ListenerTest

Initial Comment:
There's a race condition in method

    private void runTest(TestContext context, boolean
stop, 
                         int count) throws Exception

of class org.exolab.jmscts.test.connection.ListenerTest.

original code:

            // send a message and start the connection
            MessagingHelper.send(context, request, 1);
            connection.start();

should read:

            // send a message and start the connection
            connection.start();
            MessagingHelper.send(context, request, 1);

Otherwise there's a good chance that the listener hangs
forever in listener.waitForReceipt();. This happens in
pub/sub
systems when the message has already been delivered before
connection.start is called.


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>Comment By: Daniel Bauer (dnb7)
Date: 2004-01-21 09:22

Message:
Logged In: YES 
user_id=954675

The sequence in the original code is:
1.) setup listener 2.) send message 3.) start connection.
It's possible that the following happens in a pub/sub system:
1.) listener is correctly set up, but not started; i.e. no
subscription for the
topic exists.
2.) The message is sent to the pub/sub system and delivered
to all
subscribed consumers. As there are none, the message is dropped.
3.) The connection is started. As the message sent in step 2
already
left the system, no message will be delivered and the
message listener
waits at infinitum.

I think the order should be:
1.) set up listeners 2.) start connection 3.) send message.
This order is conforming to the suggested procedure of
section 4.3.3
as the setup is done before the connection is started.


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Comment By: Tim Anderson (tanderson)
Date: 2004-01-21 09:03

Message:
Logged In: YES 
user_id=557161

Don't think this is valid.
If the connection is stopped, no MessageListener should 
receive any messages. From section "4.3.3 - Connection 
Setup" of the spec:
"A JMS client typically creates a Connection, one or more 
Sessions, and a number of MessageProducers and 
MessageConsumers. When a Connection is created, it is
in stopped mode. That means that no messages are being 
delivered to it.
It is typical to leave the Connection in stopped mode until 
setup is complete. At that point the Connection’s start() 
method is called and messages begin arriving at the 
Connection’s consumers. This setup convention minimizes any 
client confusion that may result from asynchronous message 
delivery while the client is still in the process of setting itself 
up."


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