Learning DCOM

Appendix C. New COM Features and COM+

This appendix captures some of the new COM features that will likely be bundled with the up-and-coming release of Windows NT 4.0 Service Pack 4 and Windows 2000. In addition, we will briefly discuss COM+. At the time of this writing, the details of these features are fairly unstable. Because the information contained herein may be inaccurate by the time these features are released, you should verify these features for yourself if you ever intend to use them.

Throughout the book, we have talked about a number of new COM features, including:

• The Global Interface Table, which can store interface pointers that can be used by multiple apartments in the same process. This feature has been around since Windows NT 4.0 Service Pack 3.

• Delegation, which allows the server component to impersonate the client and access remote resources using the client access token. When delegation is coupled with the cloaking capability, a client token can be passed from one component to another across multiple machine hops, allowing possibly endless chaining of impersonation.

• The active directory, which supports distributed setup and administration.

• The support for structs in dispatch and dual interface definitions. This means that interface methods can contain parameters that are structs. User-defined structures have not been allowed in dispatch and dual interfaces up to now, but Windows NT 4.0 Service Pack 4 will make this feature real.

Besides these features, a couple of ...