C/C++ Code Example: Retrieving PROPID_Q_TRANSACTION
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C/C++ Code Example: Retrieving PROPID_Q_TRANSACTION

This example provides an application-defined function that retrieves the PROPID_Q_TRANSACTION property of an existing queue and returns the transaction level of the queue to the caller.

This function can return the transaction level of a local private queue from information stored on the local computer, but must retrieve information stored in the directory service to return the transaction level of a local or remote public queue. This function cannot be used to obtain the transaction level of a remote private queue.

A direct format name can be passed to this function only for a local private queue.

For information on the transaction model implemented by Message Queuing, see Message Queuing Transactions.

To retrieve PROPID_Q_TRANSACTION

  1. Define the maximum number of queue properties to be specified and the queue property counter.

  2. Define the MQQUEUEPROPS structure.

  3. Specify PROPID_Q_TRANSACTION.

  4. Initialize the MQQUEUEPROPS structure.

  5. Validate the input parameters provided by the caller.

  6. Call MQGetQueueProperties to retrieve the transaction level of the queue. If the call fails the returned error code is returned to the caller.

  7. Pass the retrieved transaction level of the queue to the caller on return.

Code Example

The following code example can be run on all versions of Message Queuing.

HRESULT GetQueueTransactionProp(
                                LPCWSTR wszQueueFormatName, 
                                UCHAR *pbValue
                                )
{
  
  // Define the maximum number of queue properties and a property counter.
  const int NUMBEROFPROPERTIES = 1;
  DWORD cPropId=0;
  
  
  // Define a queue property structure.
  MQQUEUEPROPS   QueueProps;
  QUEUEPROPID    aQueuePropId[NUMBEROFPROPERTIES];
  MQPROPVARIANT  aQueuePropVar[NUMBEROFPROPERTIES];
  HRESULT        aQueuePropStatus[NUMBEROFPROPERTIES];
  HRESULT hr = MQ_OK;

  // Validate the input parameters.
  if (wszQueueFormatName == NULL || pbValue == NULL)
  {
    return MQ_ERROR_INVALID_PARAMETER;
  }
  
  
  // Specify the PROPID_Q_TRANSACTION property.
  aQueuePropId[cPropId] = PROPID_Q_TRANSACTION;   // Property ID
  aQueuePropVar[cPropId].vt = VT_NULL;            // Type indicator
  cPropId++;
  
  
  // Initialize the MQQUEUEPROPS structure.
  QueueProps.cProp = cPropId;
  QueueProps.aPropID = aQueuePropId;
  QueueProps.aPropVar = aQueuePropVar;
  QueueProps.aStatus = aQueuePropStatus;
  
  
  
  // Get the queue properties.
  hr = MQGetQueueProperties(wszQueueFormatName, &QueueProps);
  if (FAILED(hr))
  {
    return hr;
  }
  
  
  // Set the *pbValue parameter to pass the transaction level of the queue on return.
  *pbValue = aQueuePropVar[0].bVal;
  return hr;
}
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