How to package MFC controls in a Web page

When you embed ActiveX Controls in a Web page using the OBJECT tag, the CODEBASE attribute used to specify the download location can point to a .cab file. This is the recommended way to package MFC ActiveX Controls. Packaging an MFC ActiveX Control in a cabinet file allows an .inf file to be included to control installation of the ActiveX Control, allows for dependent DLLs to be named and a location for them provided, allows for code signing, and automatically compresses the code for quicker download.

ActiveX controls are embedded in Web pages using the OBJECT tag. The CODEBASE attribute of the OBJECT tag specifies the location from which to download the control. CODEBASE can point to a number of different file types successfully.

For instance, CODEBASE can point directly to an .ocx file as follows: Because this downloads and installs only the .ocx file, this solution relies on any necessary supporting DLLs already existing on the client machine. In most cases, it should not be assumed that these DLLs will exist on the client and be the correct version.

Another alternative is for CODEBASE to point to an .inf file, for example: An .inf file controls the installation of an .ocx file and its supporting files. This method is NOT recommended because it is not possible to sign an .inf file (see the REFERENCES section for references on code signing).

The best solution is for CODEBASE to point to a cabinet file. With this method, supporting DLLs can be referenced and the cabinet file signed.

NOTE: If the directions below for referencing the MFC DLLs are followed, the MFC DLLs will not be downloaded if they already exist on the client. The CODEBASE line will resemble the following: Note here that the #Version information applies to the version of the control specified by the CLASSID parameter of the OBJECT tag.

Cab Packaging Overview

In the Cabinet Software Development Kit (also called Cabinet SDK, or CAB Development Kit) you will find the necessary tools to construct cabinet (.cab) files. See the following Microsoft Web site: The cabinet file that CODEBASE points to should contain the .ocx file and an .inf file that will control the installation of the ActiveX Control. Dependent DLLs that may already exist on the system, such as the MFC DLLs, should not be included in this cabinet file. Instead, the MFC DLLs, and other dependent DLLs, should be packaged in separate cabinet files and referenced by the control's .inf file. The following example illustrates how to package the MFC Spindial sample control.

The OBJECT tag to include the Spindial control in a Web page resembles the following: In this case, Spindial.cab must contain two files, Spindial.ocx and Spindial.inf. The command to build this cabinet file is similar to the following depending on the path to your installation of the Cabinet Development Kit: The following is an example .inf for the MFC Spindial control. This .inf file can be modified to download any MFC ActiveX Control by changing Spindial's information to the desired MFC ActiveX Control's information. See comments below. The following sections of this .inf file will need to be modified depending on your control and the version of MFC that you are using to build your control:

• Any reference to spindial should be changed to the name of your control. This includes comments and the following:

     spindial.ocx=spindial.ocx
     [spindial.ocx]
  					

• The following should be changed to the correct CLSID and FileVersion for your control:

     clsid={06889605-B8D0-101A-91F1-00608CEAD5B3}
     FileVersion=1,0,0,001
  						

  The CLSID above can be obtained for your control from the control's ODL file. The CLSID is associated with the coclass for the control. For instance, the above CLSID was obtained from the following section of Spindial.odl:

     [ uuid(06889605-B8D0-101A-91F1-00608CEAD5B3),
  
       helpstring("Spindial Control"), control ]
       coclass Spindial
  						

  The FileVersion for the control can be obtained from the version resource for the control. As is true of any file with a version resource, this can be obtained by opening the file (Spindial.ocx in this case ) version resource with Visual Studio. From the File menu, select Open, and click Open as: Resources. Open the Version resource; the FileVersion that you are interested in is listed after FILEVERSION.
• The last change that you need to make is to enter the correct FileVersion for each of the MFC DLLs, [mfc42.dll], [olepro32.dll], and [mscvrt.dll]. Note that if you are using Visual C++ 4.1 or earlier, you need to change any reference to Mfc42.dll to Mfc40.dll and any reference to Msvcrt.dll to Msvcrt40.dll.

The following FileVersions should be used:

VC 4.1 and earlier, use:

VC 4.2b and earlier, use:

VC 5.0, use:

VC 5.0sp1, use:

VC 5.0sp2, use:

VC 5.0sp3, use:

VC 6.0, use:

Notice that all versions of MFC between 4.2 and 6.0 use Mfc42.cab. This .cab file always contains the latest version of the DLLs because they are backward-compatible. If you are not compiling with a later build of MFC, you may not want to specify the latest FileVersion. Doing so may trigger an unnecessary download of the MFC DLLs.

For more information, visit the following Microsoft Developer Network (MSDN) Web sites: For more information, click the following article number to view the article in the Microsoft Knowledge Base: