Mary Kirtland is a program manager on Microsoft's COM+ team. Increasingly, you can hear her speak about COM+ at important Microsoft events such as TechEd and Professional Developers' Conference (PDC). She's also well known as the author of different articles and books on COM, MTS, and COM+. As early as November 1997, in articles for Microsoft Systems Journal (MSJ), Mary said that the basic idea behind COM+ is to simplify the development of COM components, no matter which programming language you use.
Mary Kirtland recommends that all developers of COM+ components publish the methods and properties of components through separate COM+ interfaces, also called cointerfaces. We're happy about that recommendation, which clearly supports the message we gave you in Chapter 9, "Using Separate COM Interfaces." Here follows a direct quote from Kirtland's article in the December 1997 issue of MSJ:
Unless your coclasses are very simple with short life cycles, I recommend using cointerfaces to define their public behavior and state. Define your private and protected methods, properties, and fields directly on the coclass, but otherwise use cointerfaces.