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fde · Posted: Thu Mar 12, 2009 7:22 am Post subject: MQBinding for request/response

Hello,

regarding a basic request response scenario involving writing to a queue and getting the response from the queue to continue the flow, I got some questions.

Using the ESB-MQBinding seems to always result in a MessageListener Service, connecting the queue as soon as the server starts. Not being able to access the queue has great performance impacts for the whole server.
Having more than say 5 Listeners for 5 queues, which cannot be reached results in a completly unresponsible server consuming all cpu capacity avaiable. Trying to administer, deploy or update is futile in such a case.

Those MessageListners are created for each MQ-Import. Even if the Import is just triggered through a flow.
Why does the MessageListeners has to connect to its queue at all time? There are a lot of cases, where the MqGet and the connectivity to the queue is just needed if the flow reaches the appropriated import.

Further rants:

GetByCorrelID
Accessing a queue with GetByCorrelationId is implemented as:
1. Connect to queue
2. Get the first message
3. Check the CorrelID,
- match, return the message
- no match, put the message back to queue and get the next message
4. After 20 messages not matching the correlID the Listener gives up
Doing this in this way, a lot of very usefull features and possibilities to interact with MqSeries is no longer avaiable.

Listener going to sleep
The MessageListeners for MqQueues are going to sleep after some time not being used.
The first requests brings up the Listeners again. Unfortunately the Listeners takes about 20-30 seconds to get back to life. Too long for a typical synchron flow with user interactions.

Any input, corrections or explanations are welcome.
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