MSMQ samples in C++?

Question

Can someone give me some working examples of how you can create, add messages, read from, and destroy a private message queue from C++ APIs? I tried the MSDN pieces of code but i can't make them work properly.

Thanks

Answer 1

Not quite sure how you'd go about creating or destroying message queues. Windows should create one per thread.

If you're using MFC, any CWinThread and CWnd derived class has a message queue that's trivial to access (using PostMessage or PostThreadMessage and the ON_COMMAND macro). To do something similar with the windows API, I think you need to write your own message pump, something like CWinApp's run method.

MSG msg;
BOOL bRet; 
while( (bRet = GetMessage( &msg, NULL, 0, 0 )) != 0)
{ 
    if (bRet == -1)
    {
        // handle the error and possibly exit
    }
    else
    {
        TranslateMessage(&msg); 
        DispatchMessage(&msg); 
    }
}

...is the example from the MSDN documentation. Is this what you're using? What doesn't work?

Answer 2

Actualy this is the code i was interested in:

#include "windows.h"
#include "mq.h"
#include "tchar.h"


HRESULT CreateMSMQQueue(
                        LPWSTR wszPathName, 
                        PSECURITY_DESCRIPTOR pSecurityDescriptor,
                        LPWSTR wszOutFormatName,
                        DWORD *pdwOutFormatNameLength
                        )
{

  // Define the maximum number of queue properties.
  const int NUMBEROFPROPERTIES = 2;


  // Define a queue property structure and the structures needed to initialize it.
  MQQUEUEPROPS   QueueProps;
  MQPROPVARIANT  aQueuePropVar[NUMBEROFPROPERTIES];
  QUEUEPROPID    aQueuePropId[NUMBEROFPROPERTIES];
  HRESULT        aQueueStatus[NUMBEROFPROPERTIES];
  HRESULT        hr = MQ_OK;


  // Validate the input parameters.
  if (wszPathName == NULL || wszOutFormatName == NULL || pdwOutFormatNameLength == NULL)
  {
    return MQ_ERROR_INVALID_PARAMETER;
  }



  DWORD cPropId = 0;
  aQueuePropId[cPropId] = PROPID_Q_PATHNAME;
  aQueuePropVar[cPropId].vt = VT_LPWSTR;
  aQueuePropVar[cPropId].pwszVal = wszPathName;
  cPropId++;

  WCHAR wszLabel[MQ_MAX_Q_LABEL_LEN] = L"Test Queue";
  aQueuePropId[cPropId] = PROPID_Q_LABEL;
  aQueuePropVar[cPropId].vt = VT_LPWSTR;
  aQueuePropVar[cPropId].pwszVal = wszLabel;
  cPropId++;



  QueueProps.cProp = cPropId;               // Number of properties
  QueueProps.aPropID = aQueuePropId;        // IDs of the queue properties
  QueueProps.aPropVar = aQueuePropVar;      // Values of the queue properties
  QueueProps.aStatus = aQueueStatus;        // Pointer to the return status



  WCHAR wszFormatNameBuffer[256];
  DWORD dwFormatNameBufferLength = sizeof(wszFormatNameBuffer)/sizeof(wszFormatNameBuffer[0]);
  hr = MQCreateQueue(pSecurityDescriptor,         // Security descriptor
                     &QueueProps,                 // Address of queue property structure
                     wszFormatNameBuffer,         // Pointer to format name buffer
                     &dwFormatNameBufferLength);  // Pointer to receive the queue's format name length



  if (hr == MQ_OK || hr == MQ_INFORMATION_PROPERTY)
  {
    if (*pdwOutFormatNameLength >= dwFormatNameBufferLength)
    {
      wcsncpy_s(wszOutFormatName, *pdwOutFormatNameLength - 1, wszFormatNameBuffer, _TRUNCATE);

      wszOutFormatName[*pdwOutFormatNameLength - 1] = L'\0';
      *pdwOutFormatNameLength = dwFormatNameBufferLength;
    }
    else
    {
      wprintf(L"The queue was created, but its format name cannot be returned.\n");
    }
  }
  return hr;
}

This presumably creates a queue... but there are some parts missing for this to work, that's why i need a simple example that works.