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4/8/2010

This property specifies the type of acknowledgment messages the system posts (in the administration queue) and when acknowledgments are returned.

Type Indicator

VT_UI1 (or VT_NULL)

PROPVARIANT Field

bVal

Property Values

This property can be set to one or more of the following values using the ORoperator.

Value Description

MQMSG_ACKNOWLEDGMENT_FULL_REACH_QUEUE

Posts a positive or negative acknowledgment depending on whether the message reaches the queue.

A negative acknowledgment is posted when the time-to-reach-queue timer of the message expires or when the message cannot be authenticated.

MQMSG_ACKNOWLEDGMENT_NACK_REACH_QUEUE

Posts a negative acknowledgment when the message cannot reach the queue.

A negative acknowledgment is posted when the time-to-reach-queue timer of the message expires or when the message cannot be authenticated.

MQMSG_ACKNOWLEDGMENT_FULL_RECEIVE

Posts a positive or negative acknowledgment depending on whether the message is retrieved from the queue before its time-to-be-received timer expires.

MQMSG_ACKNOWLEDGMENT_NACK_RECEIVE

Posts a negative acknowledgment when an error occurs and the message cannot be retrieved from the queue before its time-to-be-received timer expires.

MQMSG_ACKNOWLEDGMENT_NONE

The default. No acknowledgment messages (positive or negative) are posted.

Remarks

When asking for acknowledgments, you must also specify the administration queue where the acknowledgment messages will be sent.

To request acknowledgment messages, specify PROPID_M_ACKNOWLEDGE and PROPID_M_ADMIN_QUEUEin the MQMSGPROPSstructure and call MQSendMessage.

To find out if an acknowledgment message was requested for a message in a queue, specify PROPID_M_ACKNOWLEDGEin the MQMSGPROPSstructure. Then, call MQReceiveMessageand examine its returned value.

When specifying PROPID_M_ACKNOWLEDGE, you can set its Type Indicator to VT_NULL. When the Type Indicator is set to VT_NULL, MSMQ sets the VT field to the appropriate type indicator.

To receive a positive acknowledgment message when a message reaches its destination and when the message is retrieved, the following full-acknowledgment settings must be combined using the OR operator:

  • MQMSG_FULL_REACH_QUEUE

  • MQMSG_FULL_RECEIVE

Acknowledgment messages are typically MSMQ-generated messages; however, they can also be created by MSMQ connector applications when sending messages to a foreign queue.

Examples

This example shows how PROPID_M_ACKNOWLEDGE is specified in the MQMSGPROPSstructure.

Copy Code 
aMsgPropId[i] = PROPID_M_ACKNOWLEDGE;   // Property ID
aMsgPropVar[i].vt = VT_UI1; 		 // Type indicator
aMsgPropVar[i].bVal = MQMSG_ACKNOWLEDGMENT_FULL_RECEIVE;
i++;
Note:
OS versions prior to 2.12 require the MSMQ add-on pack.

Requirements

Header mq.h
Windows Embedded CE Windows CE 2.0 and later
Windows Mobile Windows Mobile Version 5.0 and later

See Also