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4/8/2010

This property specifies the length of the information in the PROPID_M_EXTENSIONproperty.

Type Indicator

VT_UI4 (or VT_NULL)

PROPVARIANT Field

ulVal

Property Values

The size (in bytes) of the extension information specified by PROPID_M_EXTENSION.

Remarks

PROPID_M_EXTENSION_LEN is used only by the receiving application. It is used when the receiving application specifies PROPID_M_EXTENSIONin the MQMSGPROPSstructure.

To retrieve extension information, set PROPID_M_EXTENSIONand PROPID_M_EXTENSION_LENin the MQMSGPROPSstructure. Then call MQReceiveMessageand examine the returned values.

When specifying PROPID_M_EXTENSION_LEN, 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.

When MQReceiveMessagesucceeds, test the returned value of PROPID_M_EXTENSION_LEN to see if extension information exists.

A returned value of 0 indicates that no information was sent by the sending application.

A nonzero returned value indicates the extension information was returned by PROPID_M_EXTENSION.

If MQReceiveMessagefails, returning an MQ_ERROR_BUFFER_OVERFLOW error, use the returned value of PROPID_M_EXTENSION_LEN to reallocate the extension information buffer and call MQReceiveMessageagain.

This property is not needed when you use COM components.

Examples

This example shows how PROPID_M_EXTENSION_LEN and PROPID_M_EXTENSION are specified in the MQMSGPROPSstructure.

Copy Code 
aMsgPropId[i] = PROPID_M_EXTENSION_LEN;  // Property ID
aMsgPropVar[i].vt = VT_UI4; 			 // Type indicator
i++;
aMsgPropId[i] = PROPID_M_EXTENSION; 	 // Property ID
aMsgPropVar[i].vt = VT_UI1 | VT_VECTOR;  // Type indicator
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