WebSphere MQ queues used in MQListener

This topic describes the typical WebSphere® MQ queues that a simple MQListener application uses.

Deadletter queue
The deadletter queue (DLQ) in WebSphere MQ holds messages that cannot be processed. MQListener uses this queue to hold replies that cannot be delivered, for example, because the queue to which the replies should be sent is full. A deadletter queue is useful in any MQ installation especially for recovering messages that are not sent.
Backout queue
For MQListener tasks in which WebSphere MQ is the transaction coordinator, the Backout queue serves a similar purpose to the deadletter queue. MQListener places the original request in the Backout queue after the request is rolled back a specified number of times (called the backout threshold).
Administration queue
The administration queue is used for routing control messages such as shutdown and restart to MQListener. If you do not supply an administration queue, then the only way to shut down MQListener is to issue a kill command.
Application input and output queues
The application uses input queues and output queues. The application receives messages from the input queue. The application sends replies and exceptions to the output queue. For example, SYSTEM.SAMPLE.REPLY is used in the WebSphere MQ sample program amqsreq.