HOWTO: Passing a License Key to ADO in Visual C++ Using MFC-OLE

• ActiveX Data Objects (ADO), version 1.0 used with: - Microsoft Visual C++, 32-bit Editions, versions 4.2, 4.2b, 5.0

SUMMARY

The MFC ClassWizard provides a powerful mechanism for manipulation OLE Automation servers by building MFC-based classes off a given typelib. The classes built wrap each object in the typelib by generating classes derived from COleDispatchDriver. However, COleDispatchDriver has no means for passing a license key. This article explains how to override the COleDispatchDriver::CreateDispatch methods to provide a license key.

MORE INFORMATION

Below is sample code for overriding the two versions of CreateDispatch(). In this case, it is from sample code for passing a license key via MFC-OLE to the ActiveX Data Objects (ADO) Connection object; however, this is incidental to the code.

Unless noted, this code is identical to the Visual C++ 5.0 version of COleDIspatchDriver::CreateDispatch(). Some macros available internally to MFC had to be replaced. Original code has been left below, but commented out to demonstrate the modifications:

   BOOL _Connection::CreateDispatch(REFCLSID clsid,
                                    COleException* pError, BSTR bstrLicKey)
   {
      ASSERT(m_lpDispatch == NULL);

      m_bAutoRelease = TRUE;  // auto-release is a good default

      // create an instance of the object
      LPUNKNOWN      lpUnknown  = NULL;
      IClassFactory2  *pIUnknown = NULL;
      IUnknown      *pOuter   = NULL;

   //   SCODE sc = CoCreateInstance(clsid, NULL,
   //                               CLSCTX_ALL | CLSCTX_REMOTE_SERVER,
   //                               IID_IUnknown, (LPLP)&lpUnknown);
      SCODE sc = CoGetClassObject( clsid,
                            CLSCTX_ALL | CLSCTX_REMOTE_SERVER,
                            NULL,
                            IID_IClassFactory2,
                            (void**) &pIUnknown );

      if (sc == E_INVALIDARG)
      {
         // may not support CLSCTX_REMOTE_SERVER, so try without
         SCODE sc = CoGetClassObject( clsid,
                               CLSCTX_ALL & ~CLSCTX_REMOTE_SERVER,
                               NULL,
                               IID_IClassFactory2,
                               (void**) &pIUnknown );

   //      sc = CoCreateInstance(clsid, NULL,
   //                            CLSCTX_ALL & ~CLSCTX_REMOTE_SERVER,
   //                            IID_IUnknown, (LPLP)&lpUnknown);

      }

      if( !FAILED( sc ) )
      {
         sc = pIUnknown->CreateInstanceLic( pOuter,
                                    NULL,
                                    IID_IUnknown,
                                    bstrLicKey,
                                    (void**)&lpUnknown );
      }

      if (FAILED(sc))
         goto Failed;

      // make sure it is running
      sc = OleRun(lpUnknown);
      if (FAILED(sc))
         goto Failed;

      // query for IDispatch interface
      // m_lpDispatch = QUERYINTERFACE(lpUnknown, IDispatch);
      if (lpUnknown->QueryInterface(IID_IDispatch,
                                    (void**)&m_lpDispatch) != S_OK)

      if (m_lpDispatch == NULL)
         goto Failed;

      lpUnknown->Release();
      ASSERT(m_lpDispatch != NULL);
      return TRUE;

   Failed:
      // RELEASE(lpUnknown);
      if( lpUnknown != NULL )
      {
         lpUnknown->Release();
         lpUnknown = NULL;
      }
      if (pError != NULL)
         pError->m_sc = sc;
      TRACE1("Warning: CreateDispatch returning scode = %s.\n",
         AfxGetFullScodeString(sc));
      return FALSE;

   }

   BOOL _Connection::CreateDispatch(LPCTSTR lpszProgID,
                                    COleException* pError,
                                    BSTR bstrLicKey)
   {
      ASSERT(m_lpDispatch == NULL);

      // map prog id to CLSID
      CLSID clsid;
      SCODE sc = AfxGetClassIDFromString(lpszProgID, &clsid);
      if (FAILED(sc))
      {
         if (pError != NULL)
            pError->m_sc = sc;
         return FALSE;
      }

      // create with CLSID
      return CreateDispatch(clsid, pError, bstrLicKey);
   }

REFERENCES

For additional information, please see the following article in the Microsoft Knowledge Base:

   ARTICLE-ID: Q168122
   TITLE     : HOWTO: Redistributing ADO 1.0 or ADO/R 1.0 with OLE/DB 1.1