Installing and Registering COM Servers and Type Libraries

Windows uses various kinds of COM servers and type libraries. Tarma Installer has built-in support for all of them as far as installation and registration is concerned (this includes unregistration and safe removal). In particular, it knows about:

• In-process COM servers, essentially dynamic link libraries (DLLs) with .dll or .ocx file name extensions and special COM-defined entry points. (The actual file name extension is immaterial; Tarma Installer analyzes each installation file to determine its type and further characteristics.)
• Out-of-process COM servers, which are stand-alone executable programs that adhere to certain COM conventions.
• Type libraries, whether embedded in DLL or EXE files, or as stand-alone TLB files. (Again, Tarma Installer does not rely upon the file name extension, but inspects each installation file to see if it contains a type library.)

Here is how Tarma Installer deals with each kind of file.

In-process COM servers

In-process COM servers have DllRegisterServer() and DllUnregisterServer() entry points that perform registration and unregistration upon request. Tarma Installer's Setup program calls these entry points as appropriate during installation and uninstallation of the server.

Out-of-process COM servers

Out-of-process COM servers adhere to the COM convention of using /RegServer and /UnregServer command line options to perform their registration and unregistration actions. When started with one of these options, the server is supposed to run invisibly and to terminate immediately after completing the (un-)registration. Tarma Installer's Setup program uses these command line options as appropriate during installation and uninstallation of the server. However, there are no hard and fast rules to recognize an out-of-process COM server, so you must judge for yourself whether or not registration is required.

Type libraries

Type libraries are sometimes contained in DLL files (often as part of an in-process COM server), sometimes in EXE files (presumably as part of an out-of-process COM server), and sometimes in a special type library file, usually with a .tlb file name extension. Tarma Installer's treatment of a type library depends on the situation, as follows:

• If the type library is contained in a DLL file and that DLL file is an in-process COM server (i.e., has a DllRegisterServer() entry point), Tarma Installer assumes that the server will register the type library as part of its overall registration process (as it should).
• If the type library is contained in a DLL file and that DLL file is not an in-process COM server, Tarma Installer will register it with the Windows function RegisterTypeLib().
• If the type library is contained in an EXE file, Tarma Installer assumes that the file is an out-of-process COM server and will suggest that it be registered as such. However, there are no hard and fast rules to recognize an out-of-process COM server, so you must judge for yourself whether or not registration is required.
• If the type library is contained in a stand-alone TLB file, Tarma Installer will register it with the Windows function RegisterTypeLib().

Once again, the actual file name extensions are immaterial; Tarma Installer analyzes each installation file to determine its type and other characteristics.

COM servers and type libraries are typically installed as shared files in the Windows System folder. Within Tarma Installer, this folder is represented by the <WinSysDir> variable. Unless you know what you are doing and have a very good reason to do otherwise, we recommend that you follow this convention.

How to add a COM server or Type Library to your project

To add a COM server or type library to your Tarma Installer project, act as follows.

1. Select the Project - Files page by clicking on its bullet in the Navigation area.

2. On the Project - Files page, create the <WinSysDir> installation folder if it isn't already present in the Installation Folders Tree. The easiest method is as follows:

   1. Right-click on Installation Files to open the installation folders context menu;
   2. Choose Insert Special Folder to open its submenu;
   3. Choose System Folder from the submenu.
3. Add the COM server's or type library's file as an installation file to the <WinSysDir> folder. If necessary, refer to Installing Files for information about adding installation files to folders.

4. Select the newly added server or type library file in the Installation Files List to display its settings in the Installation File Settings pane, then check that the following options are set:

   • Install if - Newer
   • Sharing - Untrusted reference count

   • Registration - Depends on the file type, as follows:

     • For in-process COM servers, select Use DllRegisterServer()
     • For out-of-process COM servers, select Run with /RegServer
     • For type libraries, select Use RegisterTypeLib()

   If you followed the procedure above, Tarma Installer will have set these options for you and you don't have to change anything, with the exception of out-of-process COM servers (EXE files), which cannot be recognized automatically.

5. Repeat steps 3-4 for other COM servers or type libraries.

The net result is that the server or type library will be installed and registered when your application is installed, and unregistered and removed when your application is uninstalled. All this is subject to the usual rules for file installation; in particular, Tarma Installer will correctly handle updates of existing copies of the file (based on a version check) and will only remove the file if no other applications use it. This remains true even if the SharedDlls reference count of the file is unreliable (as is often the case with third-party servers).