Developing Extension Snap-ins

Extension snap-ins make the Microsoft Management Console environment different from other management user interfaces. Generally, other management environments provide no means of adding new administration tasks. If the management environment did offer an extension mechanism, it was always a proprietary solution. For instance, suppose you were to add some voice mail features for users in an e-mail environment. You could add your application's administration tasks to the Exchange System Administrator in Microsoft Exchange 5.5. Luckily, Microsoft Exchange 5.5 does provide a mechanism to add your own property pages by implementing a DLL that exports a few functions. However, if another e-mail system were used, there would be another API to hook into and you would face the additional possibility that no such extension mechanism even exists. The result is that you end up with a fragmented administration extension mechanism for virtually every kind of administration environment. The extension mechanism provided by MMC is comprehensive, is well thought out, and most importantly, offers a unified API for developing administration applications and extending them. We regard the extension mechanism to be one of the most powerful features of MMC.

To enable the extension mechanism requires that a primary snap-in properly register the item types that can be extended. Typically, as you have little idea of how others might want to extend the management environment, you should register all the item types used within the snap-in.