Message Driven Bean Concurrency

Question

Hi:
I am working with message-driven beans (MDB). My understanding was that
these beans would read and execute concurrently. My tests show they do
not. I have setup a single MDB which contains the following trivial
implementation of onMessage...
public void onMessage(javax.jms.Message message) {
System.err.println("onMessage()");
try{
TextMessage tm = (TextMessage) message;
String text = tm.getText();
System.err.println("Received new message: " + text);
// Simulate non-trivial business process that takes ~10
seconds.
Thread.currentThread().sleep(10000);
}catch(Exception e){
e.printStackTrace();
Now I have a little test application that throws ten messages into the
queue. Each message is consumed from the queue SEQUENTIALLY which is
not my understanding of concurrent processing. So in all sending ten
messages to the queue each message is processed in turn taking 100 seconds
for the whole thing to complete instead of 10 MDB instances all chewing on
a different message and the whole thing would complete in roughly 10
seconds.
Is there a setup step that I have missed? I have bumped the
default.properties file messagebean.pool.size=30 from its default of 3.
It does create 10 bean instances, what for I don't know...
Thanks
Steve

Answer 1

Message beans are used for asynchronous calls, meaning that the container decides in what order to execute them. If you want to achieve concurrent calls consider using Session Beans.
Regards,
Dimitar