How to switch b/w 2 JMS queue managers in case of failover.?

I have 2 IBM MQ Queue Managers, one main QM and the other is standby QM.. I have written a MDB to consume messages from the Main QM queue. Now I would like to switch the connection from Main QM to standby QM in case Main Queue Manager is down. And switch back to Main QM, when it is up and running.

Any help would be much appreciated.