Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2
In the context of Message Queuing, messages can be of different types, and consist of a body and a set of properties. Message types, also called message classes, indicate the message function or disposition. The following message types are supported:
Normal messages. All messages created by Message Queuing applications are normal messages. Normal messages can be sent to public, private, and dead-letter queues of both the nontransactional and transactional types, and copies of normal messages, which are themselves normal messages, can be sent to journals when source or target journaling is enabled. Normal messages do not contain status information; such information is contained in acknowledgment, report, and response messages.
Acknowledgment messages. Acknowledgment messages report the status of normal messages. These messages are nontransactional messages that are sent to the administration queues specified in the original messages by the sending application. Acknowledgment messages can be either positive or negative. A positive acknowledgment message indicates that the original message arrived at the target queue and that it was received (removed by the receiving application). A negative acknowledgment message indicates that the original message did not reach the target queue before its time-to-reach-queue (TTRQ) elapsed, did not reach the target queue for a specified reason, that it was not received before its time-to-be-received (TTBR) elapsed, or was not received for a specified reason.
Report messages. Report messages indicate the route followed by a message as it proceeds from a source computer with tracking enabled to its destination on a remote computer. Report messages are sent to the report queue on a source computer for all messages sent from that computer with the message route tracking flag set or for only test messages sent from it.
Response messages. Response messages are messages sent by a receiving application to response queues specified by a sending application.
For more information on the various types of queues that these messages can be sent to, see Queues.
For more information on the various reasons why messages do not reach the target queue or are not received that can be specified in the message class, refer to the Message Queuing Software Development Kit (SDK).