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4/8/2010

This property specifies a label of the message.

Type Indicator

VT_LPWSTR

PROPVARIANT Field

pwszVal

Property Values

Arbitrary string (the default is none). The maximum length is 250 Unicode characters, including the end-of-string character.

Remarks

If the sending application specifies a message label longer than 250 Unicode characters, MSMQ returns an MQ_ERROR_LABEL_TOO_LONG error to the aStatusarray.

To add a label to a message, specify PROPID_M_LABELin the MQMSGPROPSstructure and call MQSendMessage.

To retrieve the label of a message, specify PROPID_M_LABEL_LENand PROPID_M_LABEL in the MQMSGPROPSstructure. Then call MQReceiveMessageand examine the returned values.

Before using the returned value, inspect the returned value of PROPID_M_LABEL_LEN to see if the sending application specified a message label.

A returned value of 0 indicates that no label was specified by the sending application.

A nonzero returned value indicates that the label was returned by PROPID_M_LABEL.

Examples

The following examples show how PROPID_M_LABEL is specified in the MQMSGPROPSstructure for setting and retrieving the message label.

To send a message label

Copy Code 
aMsgPropId[i] = PROPID_M_LABEL; 		// PropId
aMsgPropVar[i].vt = VT_LPWSTR; 		 // Type
aMsgPropVar[i].pwszVal = L"Test Message";  // Value
i++;

To retrieve the message label

Copy Code 
aMsgPropId[i] = PROPID_M_LABEL_LEN; 	// Property ID
aMsgPropVar[i].vt =VT_UI4; 			 // Type indicator
aMsgPropVar[i].ulVal = 250; 			// Label buffer size
i++;
aMsgPropId[i] = PROPID_M_LABEL; 		// Property ID
aMsgPropVar[i].vt = VT_LPWSTR; 		 // Type indicator
aMsgPropVar[i].pwszVal = wszLabelBuffer;   // Label buffer
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