Only one instance of a Message Driven Bean?

[raphael]

Hi,

I have a message driven bean which must only be instantiated
once by JBoss. The reason is that the business functionality requires that the messages are kept in the original sequence.

Now I found in the JBoss book (vers. 3.0.4) page 166 that
there is a configuration in standardjboss.xml in the section
org.jboss.ejb.plugins.MessageDrivenInstancePool
where I can configure the MaximumSize to 1 and
set strictMaximumSize to true.

That will configure JBoss to let *ALL* MDBs be singletons!

It seems to me that this is a bad idea. I would prefer a
solution where I can configure this for one specific MDB
rather than for all MDBs.

Is this possible?
Can it even be configured in the MDB's deployment descriptor?

Thanks in advance!

Raphael

[tallpsmith]

Hi,

After scrounging around the forums myself about this topic yesterday I found a method that works (but with a caveat). The JMS spec, apparantly, does not require that the message be delivered sequentially. Why? I dunno, particularly for a Queue (unless I miss read previous posts and this is only applicable to publish subscribe).

Anyway, here's my jboss.xml for the MDB test that I did that worked for me, it basically defines a specific configuration for that bean:


<enterprise-beans>
<message-driven>
<ejb-name>SimpleHelloWorldConsumer</ejb-name>
<destination-jndi-name>queue/A</destination-jndi-name>
<configuration-name>MySingletonConfig</configuration-name>
</message-driven>
</enterprise-beans>

<container-configurations>
<container-configuration extends="Standard Message Driven Bean">
<container-name>MySingletonConfig</container-name>
<container-invoker-conf>
DefaultJMSProvider
StdJMSPool
1
1

10

queue/DLQ
10
0


</container-invoker-conf>
<container-pool-conf>
1
1
true
</container-pool-conf>
</container-configuration>
</container-configurations>




cheers,

Paul Smith