.NET and COM Interoperability Handbook, The

What Is a Software Bus?

In teaching my COM and COM+ classes at UCLA Extension, I found that thinking of COM as the software equivalent of the hardware bus that exists on all PCs really helped my students. Like the hardware bus on your computer, COM provides sockets that you can plug components into. However, when you build your software components for the COM software bus, you must—in addition to building the application-specific logic of your component—build a plug that fits into the socket that the software bus provides. In COM terms, this plug is the additional logic that you must write to enable your components to work with COM: implementing the IUnknown interface, creating a class factory, and creating and registering Globally Unique Identifiers ...