Event message format

Event messages are standard WebSphere MQ messages containing a message descriptor and message data.

Message descriptor Message data
MQMD structure Event header
MQCFH structure 		Event data

Structure identifier
Structure version
Report options
Message type
Expiration time
Feedback code
Encoding
Coded character set ID
Message format
Message priority
Persistence
Message identifier
Correlation identifier
Backout count
Reply-to queue
Reply-to queue manager
User identifier
Accounting token
Application identity data
Application type
Application name
Put date
Put time
Application origin data
Group identifier
Message sequence number
Offset
Message flags
Original length
 		  
Structure type
Structure length
Structure version number
Command identifier (event type)
Message sequence number
Control options
Completion code
Reason code (MQRC_*)
Parameter count
 		  
Queue manager name
Queue name
Time since last reset
Maximum number of messages on the queue
Number of messages
put on the queue
Number of messages taken off the queue

In general, you need only a subset of this information for any system management programs that you write. For example, your application might need the following data:

  • The name of the application causing the event
  • The name of the queue manager on which the event occurred
  • The queue on which the event was generated
  • The event statistics

 

Message descriptor (MQMD) in event messages

The format of the message descriptor is defined by the MQMD data structure and contains information that can be used by a user-written system monitoring application, such as:

  • The message type
  • The format type
  • The date and time that the message was put on the event queue

In particular, the information in the descriptor informs a system management application that the message type is MQMT_DATAGRAM, and the message format is MQFMT_EVENT.

In an event message, many of these fields contain fixed data, which is supplied by the queue manager that generated the message. The fields that make up the MQMD structure are described in MQMD (message descriptor) below. The MQMD also specifies the name of the queue manager (truncated to 28 characters) that put the message, and the date and time when the event message was put on the event queue.

 

Message data in event messages

The event message data is based on the programmable command format (PCF) and consists of two parts: the event header and the event data.

 

Event header (MQCFH)

The information in MQCFH specifies:

  • If the message is an event message.
  • The category of event. Whether the event is a queue manager, performance, channel, or configuration event.
  • A reason code specifying the cause of the event. For events caused by MQI calls, this reason code is the same as the reason code for the MQI call.

Reason codes have names that begin with the characters MQRC_. For example, the reason code MQRC_PUT_INHIBITED is generated when an application attempts to put a message on a queue that is not enabled for puts. MQCFH is described in MQCFH (Event header).

 

Event data

See Event message descriptions.

 

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