Enable an MFC ActiveX Control to Self-Register

Why Self-Registering?

You have developed some ActiveX controls. If the user has to register your controls before they can be used, they will feel inconvenienced. It is better to have the components register themselves. If you use ATL to develop your ActiveX control, it comes with a self-registering capability automatically. However, if you use MFC, the control is not self-registering by default. This article shows you how to enable self-registering for MFC ActiveX controls.

What is Self-Registering?

Self-Registering means that the server enables the client to register and unregister the server at run-time. In other words, the client who wants to use the DLL server will register it if the server is enabled for self-registering. You don’t have to work with the Registry. A self-registering DLL server, for example an ATL ActiveX control, exports two functions for registering and unregistering itself: DllRegisterServer() and DllUnregisterServer(). They are called by an external program.

The procedure is as follows:

1. The client looks for the string OleSelfRegister in the version information of the server.
2. If this string is found, the client registers the server using the pointer obtained from DllRegisterServer() in the server.
3. After using the server, the client calls DllUnregisterServer() in the server to unregister it.

When you create a MFC ActiveX control using VC++, the control is not self-registering by default. To modify it to be self-registering, you need to edit the Version Information in the resource. However, the resource editor does not let you do it. You have to open the .rc file and edit it manually. All you have to do is to add:

VALUE "OLESelfRegister", "\0"

VALUE "ProductVersion", "1, 0, 0, 1\0"

After you edit, the version information block will look something like this:

VALUE "CompanyName", "MyCompany\0"
VALUE "FileDescription", "MyCtrl ActiveX Control Module\0"
VALUE "FileVersion", "1, 0, 0, 1\0"
VALUE "InternalName", " MyCtrl \0"
VALUE "LegalCopyright", "Copyright (C) 2000\0"
VALUE "LegalTrademarks", "\0"
VALUE "OriginalFilename", " MyCtrl.OCX\0"
VALUE "ProductName", " MyCtrl ActiveX Control Module\0"
VALUE "ProductVersion", "1, 0, 0, 1\0"
VALUE "OLESelfRegister", "\0"

Then you build the control again, you will get a self-registering ActiveX control.

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