Networking considerations

In a distributed-queuing environment, because message destinations are addressed with just a queue name and a queue manager name, the following rules apply:

1. Where the queue manager name is given, and the name is different from the local queue manager's name:
   • A transmission queue must be available with the same name, and this transmission queue must be part of a message channel moving messages to another queue manager, or
   • A queue manager alias definition must exist to resolve the queue manager name to the same, or another queue manager name, and optional transmission queue, or
   • If the transmission queue name cannot be resolved, and a default transmission queue has been defined, the default transmission queue is used.
2. Where only the queue name is supplied, a queue of any type but with the same name must be available on the local queue manager. This queue may be a remote queue definition which resolves to: a transmission queue to an adjacent queue manager, a queue manager name, and an optional transmission queue.

To see how this works in a clustering environment, see the WebSphere MQ Queue Manager Clusters book.

If the queue managers are running in a queue sharing group (QSG) and intra-group queuing (IGQ) is enabled, the SYSTEM.QSG.TRANSMIT.QUEUE may be used. For more information, see Chapter 37, Intra-group queuing .

Consider the scenario of a message channel moving messages from one queue manager to another in a distributed-queuing environment.

The messages being moved have originated from any other queue manager in the network, and some messages may arrive that have an unknown queue manager name as destination. This can occur when a queue manager name has changed or has been removed from the system, for example.

The channel program recognizes this situation when it cannot find a transmission queue for these messages, and places the messages on your undelivered-message (dead-letter) queue. It is your responsibility to look for these messages and arrange for them to be forwarded to the correct destination, or to return them to the originator, where this can be ascertained.

Exception reports are generated in these circumstances, if report messages were requested in the original message.