Using COM

The Component Object Model (COM) is an object-oriented programming model used by numerous applications. Because the bulk of the Microsoft® DirectX® run time is in the form of COM-compliant objects, all DirectX developers need to have at least a basic understanding of COM principles and programming techniques. Although COM has a reputation for being difficult and complex, the COM programming required by most DirectX applications is straightforward.

There are two distinct types of COM programming.

• Using existing COM objects. This is not much more difficult than using C++ objects.
• Implementing your own COM objects. This can be a complicated and demanding task. Much of COM's reputation for complexity comes from this type of COM programming.

Most DirectX applications need to use only the COM objects provided by DirectX. They do not need to implement their own COM objects. In other words, most DirectX developers will need to concern themselves only with the first, and easiest, type of COM programming.

This section provides a brief introduction to using the COM objects provided by DirectX. It is primarily intended for novice COM programmers. For a more detailed discussion of how to use COM objects, or for information about how to implement your own COM objects, see Further Information.

• What is a COM Object?
• Creating a COM Object
• Using COM Interfaces
• Managing a COM Object's Lifetime
• Using C to Access COM Objects
• Using Macros to Call DirectX COM Methods
• DirectX COM Documentation Conventions
• Using ATL with DirectX 8.x COM Interfaces
• IUnknown Interface