Defining message processing types

Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Defining message processing types

A message processing type is defined for each trigger. The available message processing types are peeking, retrieval, and transactional retrieval.

When peeking is selected as the message processing type for a given trigger and the Message Queuing Triggers service is running, it peeks at each message arriving at the monitored queue, tests it for the conditions of all the rules associated with the queue, and performs all the applicable actions, but does not remove it from the queue.

When retrieval is selected as the message processing type, the Message Queuing Triggers service peeks at each message arriving at the monitored queue, tests it for the conditions of all the rules associated with the queue, and invokes all the applicable actions. If at least one condition is satisfied, and no invoked action fails, the message is removed from the queue.

The transactional retrieval type of message processing is similar to the retrieval type, but in this case the message is returned to the queue if any of the operations involved in retrieving the message cannot be completed and the retrieval transaction is aborted.

When messages arrive at a monitored queue, Message Queuing does not limit access to these messages to the Message Queuing Triggers service. Thus, it is possible for another Message Queuing application to open the queue and remove messages before the Message Queuing Triggers service manages to process those messages.