MQSeries.net :: View topic - MQ JMS doesnt initiate connection to MQ server automatically

glen254 · Posted: Mon Jan 07, 2008 4:30 am Post subject:

We have a MQ JMS implementation that makes use of client connection calls to a remote MQ server to pick up messages and process them via MDBs

The MQ JMS client and MQ Server are on 2 different servers.
The MQ version is 6.0
The operating system is Windows XP

The MQ JMS implementation is done as follows

1. We create/lookup the JMSConnectionFactory(In this case, we are creating MQQueueConnectionFactory and setting the properties such as hostname, port etc).
2. From the ConnectionFactory, we call createConnection which gives us the JMS Providers connection.
3. We call start method on the Connection.
4. We create a ServerSessionPool which actually holds the threads and Message Listener.
5. We create a connectionConsumer on the connection using connection.createConnectionConsumer() with ServerSessionPool as one of the params.
6. Now, the connectionConsumer is the one that is actually responsible for receiving the messages from MQServer and pushing them to MDB. The following is the flow used in most of the JMS Server implementations:

When ConnectionConsumer sees that there are messages on the Queue, it fetches them and tries to get a ServerSession from the ServerSessionPool. This object will have a session created on the Connection and the ConnectionConsumer will call start on the ServerSession. This inturn registers a MDB as the message listener on the Session. The session will inturn call the onMessage of the MDB.

This configuration works fine when there is network connectivity between the client and MQ server.

Now when there is a network failure (test was carried out by manually disconnecting the MQ server by detaching the n/w cable), the client goes into a retry mode. The retry count is calculated from the 'Hearbeat Interval' on the SYSTEM.DEF.SVRCONN channel and is arrived as below

Retry interval = Heartbeat Interval * 1000 + 60000

which means - that if the Heartbeat Interval is 300 seconds, then the retry timeout will be 360 seconds

When a n/w failure scenario is simulated, the logs clearly show the retries tacking place and after 6 minutes (360 seconds) a callback is given to the ExceptionListener - onException() method.

This working is fine if the n/w was down during this 6 minute interval. But even when the n/w cable is plugged back into the MQ server within 15-20 seconds, the MQ JMS implementation does not automatically reinitiate the connection itself. It is noticed that the callback to the ExceptionListener is done after 6 minutes

In this case -

1. Does MQ JMS reinitiate the connection automatically (if possible) without having to notify the ExceptionListener??

2. Would the ExceptionListener always be notified after the timeout interval even after the network is back up??