PROPID_M_CLASS

Article
10/19/2016

Applies To: Windows 10, Windows 7, Windows 8, Windows 8.1, Windows Server 2008, Windows Server 2008 R2, Windows Server 2012, Windows Server 2012 R2, Windows Server Technical Preview, Windows Vista

The PROPID_M_CLASS property indicates message type. A message can be a normal Message Queuing message, a positive or negative (arrival and read) acknowledgment message, or a report message. For negative acknowledgment messages, the value of this property can indicate why the message did not arrive or was not retrieved. Typically this property is set by Message Queuing when it sends the message, however it can also be set by a connector application when the connector application sends a message.

Property ID

PROPID_M_CLASS

Type Indicator

VT_UI2

MQPROPVARIANT Field

uiVal

Property Value

Normal messages (all messages created by your application):

MQMSG_CLASS_NORMAL

A normal Message Queuing message.

Positive arrival acknowledgment message (typically generated by Message Queuing):

MQMSG_CLASS_ACK_REACH_QUEUE

The original message reached its destination queue.

Negative arrival acknowledgment messages (typically generated by Message Queuing):

MQMSG_CLASS_NACK_ACCESS_DENIED

The access rights for placing messages in the destination queue are not allowed for the sending application.

MQMSG_CLASS_NACK_BAD_DST_Q

The destination queue is not available to the sending application.

MQMSG_CLASS_NACK_BAD_ENCRYPTION

The destination queue manager could not decrypt a private (encrypted) message (see PROPID_M_PRIV_LEVEL).

MQMSG_CLASS_NACK_BAD_SIGNATURE

Message Queuing could not authenticate the original message. The digital signature attached to the original message is not valid.

MQMSG_CLASS_NACK_COULD_NOT_ENCRYPT

The source queue manager could not encrypt a private message (PROPID_M_PRIV_LEVEL).

MQMSG_CLASS_NACK_HOP_COUNT_EXCEEDED

The hop count of the original message is exceeded.

MQMSG_CLASS_NACK_NOT_TRANSACTIONAL_MSG

A nontransactional message was sent to a transactional queue.

MQMSG_CLASS_NACK_NOT_TRANSACTIONAL_Q

A transactional message was sent to a nontransactional queue.

MQMSG_CLASS_NACK_PURGED

The message was purged before reaching the destination queue.

MQMSG_CLASS_NACK_Q_EXCEED_QUOTA

The destination queue of the original message is full.

MQMSG_CLASS_NACK_REACH_QUEUE_TIMEOUT

Either the time-to-reach-queue or time-to-be-received timer expired before the original message could reach the destination queue.

For transactional messages, this is an in-doubt negative acknowledgment. For example, the local queue manager will set this class when the message timer expires, even though a positive confirmation may be in route from the remote queue manager.

MQMSG_CLASS_NACK_SOURCE_COMPUTER_GUID_CHANGED

The source computer joined a domain or moved to a new forest while the transactional message was waiting in an outgoing queue to be delivered to its destination. As a result, the source computer has a new msmq (MSMQ-Configuration) object with a new GUID, so the message was moved to the transactional dead-letter queue or discarded to prevent a possible duplicate message from reaching the destination queue.

MQMSG_CLASS_NACK_UNSUPPORTED_CRYPTO_PROVIDER

The destination queue manager does not have the enhanced (128-bit) cryptographic provider installed.

Positive read acknowledgment message (typically generated by Message Queuing):

MQMSG_CLASS_ACK_RECEIVE

The original message was retrieved by the receiving application.

Negative read acknowledgment messages (typically generated by Message Queuing):

MQMSG_CLASS_NACK_Q_DELETED

The queue was deleted before the message could be read from the queue.

MQMSG_CLASS_NACK_Q_PURGED

The queue was purged, and the message no longer exists.

MQMSG_CLASS_NACK_RECEIVE_TIMEOUT

The original message was not removed from the queue before its time-to-be-received timer expired.

For transactional message, the remote queue manager has indicated that the message was not retrieved. This is the only negative acknowledgment that can be trusted to indicate the message was not retrieved.

MQMSG_CLASS_NACK_RECEIVE_TIMEOUT_AT_SENDER

For transactional messages only. The local queue manager has indicated that the original message was not removed from the queue before its time-to-be-received timer expired.

This class is an in-doubt negative acknowledgment. For example, the local queue manager will set this class when the time-to-be-received timer expires, even though a positive confirmation may be in route from the remote queue manager.

Report messages (typically generated by Message Queuing):

MQMSG_CLASS_REPORT

Sent each time the message enters or leaves a Message Queuing server.

Remarks

Acknowledgment messages are typically generated by Message Queuing whenever the sending application requests them. The acknowledgment message is returned to the administration queue that is specified by the sending application.

Note

Acknowledgment messages can also be created by connector applications. When the connector application creates an acknowledgment message, it must set PROPID_M_CLASS and PROPID_M_CONNECTOR_TYPE.

Transactional messages can have two in-doubt negative acknowledgments: MQMSG_CLASS_NACK_REACH_QUEUE_TIMEOUT and MQMSG_CLASS_NACK_RECEIVE_TIMEOUT_AT_SENDER. These two classes are considered in doubt because they can be set by the local queue manager even though a confirmation notification may be in route from the remote queue manager. The only trusted negative acknowledgment is MQMSG_CLASS_NACK_RECEIVE_TIMEOUT, because this class is set by the remote queue manager.

Report messages are typically generated by Message Queuing whenever a report queue is defined at the source queue manager. For information on report queues, see Report Queues.

To retrieve the class of the message, specify PROPID_M_CLASS in the MQMSGPROPS structure. Then call MQReceiveMessage or MQReceiveMessageByLookupId and examine the returned value. The type indicator of this property can be set to VT_UI2 or VT_NULL. If you set the type indicator to VT_NULL, Message Queuing automatically changes the type indicator to VT_UI2 during the function call.

When reading messages in an administration queue or dead-letter queue, retrieve PROPID_M_CLASS to find out why the message was sent to the queue.

Equivalent COM Property

With COM components, the equivalent property for retrieving the message class is MSMQMessage.MsgClass.

For information on	See
What is in acknowledgment messages.	Acknowledgment Messages
The type of queues used as administration queues	Administration Queues
How dead-letter queues are used	Dead-Letter Queues
Connector applications	Connector Application Security

Example Code

The following code fragment shows how PROPID_M_CLASS is specified in arrays that can be used to initialize an MQMSGPROPS structure to ascertain the message class:

aMsgPropID[i] = PROPID_M_CLASS;    //Property ID  
aMsgPropVar[i].vt = VT_NULL;       //Type indicator

The following examples are included in Using Message Queuing.

For an example of	See
Filtering messages in an administration queue according to the acknowledgment class of the messages	C/C++ Code Example: Acknowledgment Class Filter
Setting the acknowledgment class when an acknowledgment message is sent at the request of a connector application	C/C++ Code Example: Returning Acknowledgment Messages (Connector Applications)

PROPID_M_CLASS

Property Value

Remarks

Example Code

See Also

Additional resources