How To Create an Automation Client Project Using ATL

This article demonstrates how to build a simple Automation client application using ATL.

The following section illustrates how you can create an ATL client EXE project that automates Microsoft Excel. You can use the first 10 steps for any project, and modify step 11 when you work with another application.

Create an Automation Project

1. With Microsoft Developer Studio 6.0, start a new "ATL COM AppWizard" project named "AtlClientApp."
2. In step 1 of the ATL AppWizard, choose "Executable (EXE)" for the Server Type and then click Finish. The New Project Information dialog box appears and shows the classes to be created. Click OK to create the project.
3. From the Insert menu, select "New ATL Object" to bring up the ATL Object Wizard. For the type of Object to insert, select Miscellaneous and pick Dialog to a add a Dialog Object to the project. Click Next to continue.
4. Provide a short name of "ClientDlg" for your new dialog. Accept the defaults for all other names and click OK.
5. In the project workspace, click the "Resource View" tab. Double-click "AtlClientApp Resources" to expand the resource tree. Double-click Dialog in the Resource tree and double-click to select the dialog box resource "IDD_CLIENTDLG."
6. Change the caption of the OK button to "Run" and the cancel button to "Quit." Leave the button IDs at their default settings and close the dialog box design form.
7. In the project workspace, click the "Class View" tab. Double-click the "Globals" folder to see the "_tWinMain" entry point, then double-click "_tWinMain" to jump to the code location.
8. Replace all the code in the function with the following:

         extern "C" int WINAPI _tWinMain(HINSTANCE hInstance,
            HINSTANCE /*hPrevInstance*/, LPTSTR lpCmdLine, int /*nShowCmd*/)
         {
   
            HRESULT hRes = CoInitialize(NULL);
            _ASSERTE(SUCCEEDED(hRes));
            _Module.Init(NULL, hInstance);
            _Module.dwThreadID = GetCurrentThreadId();
   
            int nRet = 0;
   
            CClientDlg*  pDlg = NULL;
   
            pDlg = new CClientDlg;
            if(NULL != pDlg)
            {
               pDlg->Create(NULL);
               pDlg->ShowWindow(SW_NORMAL);
   
               MSG msg;
               while (GetMessage(&msg, 0, 0, 0))
               {
                  TranslateMessage(&msg);
                  DispatchMessage(&msg);
               }
               nRet = msg.wParam;
               delete pDlg;
            }
   
            CoUninitialize();
            return nRet;
         }
   					

9. At the top of the file, add the following include statement after the others:

         #include "ClientDlg.h"
   					

10. From the "Class View" tab, expand the "CClientDlg" class to reveal its class members. Find the "OnCancel" method and double-click it to jump to the code. Replace the code in the function with the following:

          LRESULT CClientDlg::OnCancel(WORD wNotifyCode, WORD wID,
             HWND hWndCtl, BOOL& bHandled)
          {
             DestroyWindow();
             PostQuitMessage(0);
             return 0;
          }
    					

11. Replace the code in the "OnOK" method with the following:

          LRESULT CClientDlg::OnOK(WORD wNotifyCode, WORD wID,
             HWND hWndCtl, BOOL& bHandled)
          {
             IDispatch*  pDisp;   // Main IDispatch pointer.
             CLSID       clsid;   // Holds CLSID of server
             DISPID      dispID;  // Temporary variable to hold DISPIDs.
             HRESULT     hr;      // General error/result holder.
    
             hr = CLSIDFromProgID(L"Excel.Application", &clsid);
             if(FAILED(hr)){
                MessageBox("Excel is not installed.");
                return 0;}
    
             hr = CoCreateInstance(clsid, NULL, CLSCTX_LOCAL_SERVER,
                IID_IDispatch, (void **)&pDisp);
             if(FAILED(hr)){
    
                MessageBox("Couldn't start Excel.");
                return 0;}
    
             OLECHAR    *szVisible = L"Visible";
             DISPPARAMS dispParams = { NULL, NULL, 0, 0 };
             DISPID dispidNamed = DISPID_PROPERTYPUT;
             CComVariant vrTrue = VARIANT_TRUE;
    
             pDisp->GetIDsOfNames(IID_NULL, &szVisible, 1,
                LOCALE_USER_DEFAULT, &dispID);
    
             dispParams.cArgs = 1;
             dispParams.rgvarg = &vrTrue;
             dispParams.cNamedArgs = 1;
             dispParams.rgdispidNamedArgs = &dispidNamed;
    
             // Set 'Visible' property to true.
             pDisp->Invoke(dispID, IID_NULL, LOCALE_SYSTEM_DEFAULT,
                DISPATCH_PROPERTYPUT | DISPATCH_METHOD, &dispParams,
                NULL, NULL, NULL);
    
             MessageBox("We're done.", "Finish", MB_SETFOREGROUND);
    
             // Release the IDispatch pointer before exit
             pDisp->Release();
             return 0;
          }
    					

12. Because you are building a client application, you do not need to perform COM registration when you compile the EXE. To remove this step, select "Settings" from the Project menu, go to the "Custom Build" tab, and remove the all the commands that appear in the "Build Commands" window. Do the same for the "Outputs" window, and click OK when done.
13. Compile your project by selecting "Rebuild All" from the Build menu. Run your project by pressing the F5 key.

For additional information on the Automation of Office from Visual C++, please see the Microsoft Knowledge Base article found at this Web site: