When an object handler is installed, the handler must register itself in the registration database. The registration process is the same as for registering server applications, but the keyword handler must be used. For more information on registering object handlers, see Chapter 10, "Using the Registration Database."
For example, to register StdFileEditing protocol for a handler for a specific ClassName and Dllname, use the following format in the text file that is merged into the registration database with REGEDIT.EXE:
HKEY_CLASSES_ROOT\Classname\protocol\StdFileEditing\handler = Dllname
Whenever a client application calls one of the object-creation functions, the client DLL uses the class name specified for the object and the handler keyword to search the registration database. If an object handler is found for the specific class, it is loaded and initialized.
Since handlers usually are designed to work with particular servers, the registration database entry should be added to the related server entries.