Channel-exit programs for messaging channels

This collection of topics contains information about IBM MQ channel-exit programs for messaging channels.

Message channel agents (MCAs) can also call data-conversion exits. For more information about writing data-conversion exits, see Writing data-conversion exits.

Some of this information also applies to exits on MQI channels, which connect IBM MQ MQI clients to queue managers. For more information, see Channel-exit programs for MQI channels.

Channel-exit programs are called at defined places in the processing carried out by MCA programs.

Some of these user-exit programs work in complementary pairs. For example, if a user-exit program is called by the sending MCA to encrypt the messages for transmission, the complementary process must be functioning at the receiving end to reverse the process.

Table 1 shows the types of channel exit that are available for each channel type.

1. On z/OS, the auto-definition exit applies to cluster-sender and cluster-receiver channels only.

If we are going to run channel exits on a client, we cannot use the MQSERVER environment variable. Instead, create and reference a client channel definition table (CCDT) as described in Client channel definition table.

• Processing overview
  An overview of how MCAs use channel-exit programs.
• Writing channel-exit programs
  We can use the following information to help you write channel-exit programs.
• Compiling channel exit programs on Windows, UNIX and Linux systems
  Use the following examples to help you compile channel-exit programs for Windows, UNIX and Linux systems.
• Configure channel exits
  To call the channel exit, we must name it in the channel definition.

Parent topic: User exits, API exits, and IBM MQ installable services