Concepts

This section describes the concepts of intra-group queuing.

Intra-group queuing (IGQ) can effect potentially fast and less-expensive small message transfer between queue managers within a queue-sharing group (QSG), without the need to define channels between the queue managers. That is, intra-group queuing can be used to deliver, more efficiently, small messages to queues residing on remote queue managers within a queue-sharing group.

Intra-group queuing and the intra-group queuing agent

An IGQ agent is started during queue manager initialization. When applications open and put messages to remote queues, the local queue manager determines whether intra-group queuing should be used for message transfer. If intra-group queuing is to be used, the local queue manager places the message on to the SYSTEM.QSG.TRANSMIT.QUEUE. The IGQ agent on the target remote queue manager retrieves the message and places it on to the destination queue.

The following diagram shows a typical example of intra-group queuing.

Figure 91. An example of intra-group queuing

The diagram shows:

• IGQ agents running on three queue managers (QMG1,QMG2 and QMG3) that are defined to a queue-sharing group called SQ26.
• Shared transmission queue SYSTEM.QSG.TRANSMIT.QUEUE that is defined in the Coupling Facility (CF).
• A remote queue definition that is defined in queue manager QMG1.
• A local queue that is defined in queue manager QMG2.
• A requesting application (this could be a Message Channel Agent (MCA)) that is connected to queue manager QMG1.
• A server application that is connected to queue manager QMG2.
• A request message being placed on to the SYSTEM.QSG.TRANSMIT.QUEUE.