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C/C++ Code Example: Setting PROPID_Q_QUOTA

This example provides an application-defined function that sets the PROPID_Q_QUOTA property of an existing queue based on a given maximum queue size provided by the caller.

Setting this property for an existing queue changes the maximum size of the queue, however, it has no effect on messages already in the queue.

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

To set PROPID_Q_QUOTA

  1. Validate the input parameters provided by the caller.

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

  3. Define the MQQUEUEPROPS structure.

  4. Specify PROPID_Q_QUOTA.

  5. Initialize the MQQUEUEPROPS structure.

  6. Call MQSetQueueProperties to set the maximum size of the queue. If the call fails, the returned error code is returned to the caller.

Code Example

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

HRESULT SetQueueQuotaProp(
                          LPCWSTR wszQueueFormatName,
                          int iValue
                          )
{
  
  // Validate the input string.
  if (wszQueueFormatName == NULL)
  {
    return MQ_ERROR_INVALID_PARAMETER;
  }


  // 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;
  
  
  // Specify the PROPID_Q_QUOTA property.
  aQueuePropId[cPropId] = PROPID_Q_QUOTA;         // Property ID
  aQueuePropVar[cPropId].vt = VT_UI4;             // Type indicator
  aQueuePropVar[cPropId].ulVal = iValue;          // Queue quota
  cPropId++;
  
  
  // Initialize the MQQUEUEPROPS structure.
  QueueProps.cProp = cPropId;
  QueueProps.aPropID = aQueuePropId;
  QueueProps.aPropVar = aQueuePropVar;
  QueueProps.aStatus = aQueuePropStatus;
  
  
  // Set the queue properties.
  hr = MQSetQueueProperties(wszQueueFormatName, &QueueProps);
  return hr;
}
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