Understanding The COM Single-Threaded Apartment Part 1

#define _WIN32_WINNT 0x0400
#include <windows.h>
#include <stdio.h>
#include "ExeServerInterfaces.h"
#include "ExeServerInterfaces_i.c"





// Simple function that displays the current thread ID.
void DisplayCurrentThreadId()
{
  TCHAR szMessage[256];

  sprintf (szMessage, "Thread ID : 0x%X", GetCurrentThreadId());

  ::MessageBox(NULL, szMessage, "TestMethod1()", MB_OK);
}





int main()
{
  IExeObj01* pIExeObj01A = NULL;
  IExeObj01* pIExeObj01B = NULL;
  IExeObj02* pIExeObj02A = NULL;
  IExeObj02* pIExeObj02B = NULL;
  IExeObj03* pIExeObj03A = NULL;
  IExeObj03* pIExeObj03B = NULL;

  //HRESULT hr = ::CoInitializeEx(NULL, COINIT_APARTMENTTHREADED);
  HRESULT hr = ::CoInitializeEx(NULL, COINIT_MULTITHREADED);

  ::CoCreateInstance
  (
    CLSID_ExeObj01,     //Class identifier (CLSID) of the object
    NULL, //Pointer to controlling IUnknown
    CLSCTX_LOCAL_SERVER,  //Context for running executable code
    IID_IExeObj01,         //Reference to the identifier of the interface
    (LPVOID*)&pIExeObj01A         //Address of output variable that receives 
                           // the interface pointer requested in riid
  );

  ::CoCreateInstance
  (
    CLSID_ExeObj01,     //Class identifier (CLSID) of the object
    NULL, //Pointer to controlling IUnknown
    CLSCTX_LOCAL_SERVER,  //Context for running executable code
    IID_IExeObj01,         //Reference to the identifier of the interface
    (LPVOID*)&pIExeObj01B         //Address of output variable that receives 
                           // the interface pointer requested in riid
  );

  ::CoCreateInstance
  (
    CLSID_ExeObj02,     //Class identifier (CLSID) of the object
    NULL, //Pointer to controlling IUnknown
    CLSCTX_LOCAL_SERVER,  //Context for running executable code
    IID_IExeObj02,         //Reference to the identifier of the interface
    (LPVOID*)&pIExeObj02A         //Address of output variable that receives 
                           // the interface pointer requested in riid
  );

  ::CoCreateInstance
  (
    CLSID_ExeObj02,     //Class identifier (CLSID) of the object
    NULL, //Pointer to controlling IUnknown
    CLSCTX_LOCAL_SERVER,  //Context for running executable code
    IID_IExeObj02,         //Reference to the identifier of the interface
    (LPVOID*)&pIExeObj02B         //Address of output variable that receives 
                           // the interface pointer requested in riid
  );

  ::CoCreateInstance
  (
    CLSID_ExeObj03,     //Class identifier (CLSID) of the object
    NULL, //Pointer to controlling IUnknown
    CLSCTX_LOCAL_SERVER,  //Context for running executable code
    IID_IExeObj03,         //Reference to the identifier of the interface
    (LPVOID*)&pIExeObj03A         //Address of output variable that receives 
                           // the interface pointer requested in riid
  );

  ::CoCreateInstance
  (
    CLSID_ExeObj03,     //Class identifier (CLSID) of the object
    NULL, //Pointer to controlling IUnknown
    CLSCTX_LOCAL_SERVER,  //Context for running executable code
    IID_IExeObj03,         //Reference to the identifier of the interface
    (LPVOID*)&pIExeObj03B         //Address of output variable that receives 
                           // the interface pointer requested in riid
  );

  if (pIExeObj01A)
  {
    pIExeObj01A -> TestMethod1();
  }

  if (pIExeObj01B)
  {
    pIExeObj01B -> TestMethod1();
  }

  if (pIExeObj02A)
  {
    pIExeObj02A -> TestMethod1();
  }

  if (pIExeObj02B)
  {
    pIExeObj02B -> TestMethod1();
  }

  if (pIExeObj03A)
  {
    pIExeObj03A -> TestMethod1();
  }

  if (pIExeObj03B)
  {
    pIExeObj03B -> TestMethod1();
  }

  if (pIExeObj01A)
  {
    pIExeObj01A -> Release();
	pIExeObj01A = NULL;
  }

  if (pIExeObj01B)
  {
    pIExeObj01B -> Release();
	pIExeObj01B = NULL;
  }

  if (pIExeObj02A)
  {
    pIExeObj02A -> Release();
	pIExeObj02A = NULL;
  }

  if (pIExeObj02B)
  {
    pIExeObj02B -> Release();
	pIExeObj02B = NULL;
  }

  if (pIExeObj03A)
  {
    pIExeObj03A -> Release();
	pIExeObj03A = NULL;
  }

  if (pIExeObj03B)
  {
    pIExeObj03B -> Release();
	pIExeObj03B = NULL;
  }

  ::CoUninitialize();

  return 0;
}