Developers Workshop to COM and ATL 3.0

Objectives:

• Review the functionality provided by CComModule.

• Dissect the ATL Object Map and the _ATL_OBJMAP_ENTRY structure.

• Implement alternative class factories for ATL coclasses.

• Learn to customize your server's registration duties.

• Distinguish between creatable and non-creatable coclasses.

• Understand (and use) COM categories.

In this chapter, you will spend some time digging deeper into ATL's support for COM servers. Although you already understand that the ATL COM AppWizard can be used to quickly put together a component home, we have yet to understand the details of exactly how the ATL framework is managing this. We begin by examining a number of methods of CComModule, and will quickly see that CComModule can't do much without an object map close by. The bulk of this chapter will be spent coming to understand exactly what this map is up to.

You will learn how to create customized registration of your ATL coclasses, as well as examine a number of more advanced COM topics, such as COM categories (CATIDs) and non-creatable coclasses, and how to develop a more sophisticated class factory than the framework provided default.