Format of event messages

Event messages contain information about an event and its cause. Like other IBM MQ messages, an event message has two parts: a message descriptor and the message data.

• The message descriptor is based on the MQMD structure.
• The message data consists of an event header and the event data. The event header contains the reason code that identifies the event type. Putting the event message, and any subsequent action, does not affect the reason code returned by the MQI call that caused the event. The event data provides further information about the event.

Typically, you process event messages with a system management application tailored to meet the requirements of the enterprise at which it runs.

When the queue managers in a queue sharing group detect the conditions for generating an event message, several queue managers can generate an event message for the shared queue, resulting in several event messages. To ensure that a system can correlate multiple event messages from different queue managers, these event messages have a unique correlation identifier (CorrelId) set in the message descriptor (MQMD).