Retrieving PROPID_Q_QUOTA

The queue's quota is the maximum size of the queue. By default, a queue's maximum size is set to INFINITE.

To retrieve PROPID_Q_QUOTA

1. Define the structures needed to retrieve the properties. This includes the MQQUEUEPROPS structure.

   // Define number of properties to be retrieved
   #define NumberOfProperties 1
   
   // Define property counter.
   DWORD PropIdCount = 0;
   
   // Define the MQQUEUPROPS structure.
   MQQUEUEPROPS QueueProps;
   PROPVARIANT aQueuePropVar[NumberOfProperties];
   QUEUEPROPID aQueuePropId[NumberOfProperties];
   HRESULT aQueueStatus[NumberOfProperties];
   
   // Define results.
   HRESULT hr;
   
   // Define format name buffer.
   DWORD dwFormatNameBufferLength = 256;
   WCHAR szFormatNameBuffer[256];
   

2. Specify PROPID_Q_QUOTA.

   aQueuePropId[PropIdCount] = PROPID_Q_QUOTA;     //Property ID
   aQueuePropVar[PropIdCount].vt = VT_UI4;         //Type indicator
   PropIdCount++;
   

3. Add any additional queue properties. When adding properties, increment the NumberOfProperties variable to reflect the number of properties added.
4. Set the MQQUEUEPROPS structure.

   QueueProps.cProp = PropIdCount;           // Number of properties
   QueueProps.aPropID = aQueuePropId;        // Ids of properties
   QueueProps.aPropVar = aQueuePropVar;      // Values of properties
   QueueProps.aStatus = aQueueStatus;        // Error reports
   

5. Obtain the format name of the queue. The example below uses MQPathNameToFormatName to obtain the format name of a known queue. Other functions that can be used are MQHandleToFormatName and MQInstanceToFormatName.

   hr = MQPathNameToFormatName(L"machinename\\queuename",
                                 szFormatNameBuffer,
                                     &dwFormatNameBufferLength);
   if (FAILED(hr))
      {
      fprintf(stderr, "Failed in MQPathNameToFormatName, error = 0x%x\n",hr);
      return -1;
      }

6. Call MQGetQueueProperties.

   hr = MQGetQueueProperties(szFormatNameBuffer, &QueueProps);
   if (FAILED(hr))
      {
      fprintf(stderr, "Failed in MQGetQueueProperties, error = 0x%x\n",hr);
      return -1;
      }
    

7. Examine the returned value of the property.

   printf("The maximum size of the queue is ");
   
     if (aQueuePropVar[0].ulVal == -1)
         printf("INFINITE. \n");
         else
         printf("%d.\n",aQueuePropVar[0].ulVal);
   

Example Code

The following example retrieves the PROPID_Q_QUOTA property for a known queue and then prints the returned value to the screen.

#include <windows.h>
#include <stdio.h>
#include <mq.h>                       // MSMQ header file


int main(int arg, char *argv[])

{
  ///////////////////////////
  //  Define structures.
  ////////////////////////////

  // Define number of properties to be retrieved.
  #define NumberOfProperties 1

  // Define property counter.
  DWORD PropIdCount = 0;

  // Define the MQQUEUPROPS structure.
  MQQUEUEPROPS QueueProps;
  PROPVARIANT aQueuePropVar[NumberOfProperties];
  QUEUEPROPID aQueuePropId[NumberOfProperties];
  HRESULT aQueueStatus[NumberOfProperties];
  
  // Define results.
  HRESULT hr;
  
  // Define format name buffer.
  DWORD dwFormatNameBufferLength = 256;
  WCHAR szFormatNameBuffer[256];
  
  
  ///////////////////////////////////
  // Specify PROPID_Q_QUOTA.
  ///////////////////////////////////
  
  aQueuePropId[PropIdCount] = PROPID_Q_QUOTA;    // Property ID
  aQueuePropVar[PropIdCount].vt = VT_UI4;        // Type indicator
  PropIdCount++;
  
  
  ///////////////////////////////////////////////////////
  // Add additional queue properties here. When adding 
  // properties, increment NumberOfProperties to 
  // reflect total number of properties.
  ///////////////////////////////////////////////////////
  
  
  ////////////////////////////////
  // Set the MQQUEUEPROPS structure.
  /////////////////////////////////
  
  QueueProps.cProp = PropIdCount;           // Number of properties
  QueueProps.aPropID = aQueuePropId;        // Ids of properties
  QueueProps.aPropVar = aQueuePropVar;      // Values of properties
  QueueProps.aStatus = aQueueStatus;        // Error reports
  
  
  ////////////////////////////
  //Get format name of queue.
  ////////////////////////////
 
  hr = MQPathNameToFormatName(L"computername\\queuename",
                              szFormatNameBuffer,
                                  &dwFormatNameBufferLength);
  if (FAILED(hr))
  {
    fprintf(stderr, "Failed in MQPathNameToFormatName, error = 0x%x\n",hr);
  return -1;
  }
 
 
  ////////////////////////////
  // Get queue property.
  ////////////////////////////
  
  hr = MQGetQueueProperties(szFormatNameBuffer, &QueueProps);
  if (FAILED(hr))
  {
    fprintf(stderr, "Failed in MQGetQueueProperties, error = 0x%x\n",hr);
    return -1;
  }
  
  
  //////////////////////////////////////////////
  // Review returned value. This example prints 
  // out the maximum size of the queue.
  //////////////////////////////////////////////
  
  printf("The maximum size of the queue is ");
  
  if (aQueuePropVar[0].ulVal == -1)
     printf("INFINITE. \n");
     else
     printf("%d.\n",aQueuePropVar[0].ulVal);
  
  return 0;
 
}