Beginning ATL COM Programming

The book covers programming the latest version of the Active Template Library ( ATL ) which is currently in version 2.1. The book uses Visual C++ 5 as the programming environment. Earlier versions of VC++, back to 4.0 may be used in conjunction with the ATL additions that can be downloaded from Microsoft. VC++ is increasingly used to develop ActiveX components for use elsewhere, for example in VB or on the Web. These components have to small and light, and be able to interoperate with whatever their host application is. COM is the Microsoft technology that allows the components to interoperate, while ATL is a tool that simplifies the creation of these components. Where VC++ programmers use MFC to create stand alone applications, ATL is a lighter, faster substitute for creating just components.

The Active Template Library (ATL) is the part of the Microsoft Foundation Classes (MFC) used to build reusable and very efficient components in C++. Achieving this efficiency can be difficult, as it requires you to delve into the details of Microsoft's Component Object Model (COM) and ATL itself. With Beginning ATL COM Programming, however, it should be possible for any C++/MFC programmer to become productive with this exciting component technology.

The book begins with the basics of COM programming, featuring good details on the actual Win32 APIs used throughout COM programming. (This section also discusses the basics of the component definition, including Interface Definition Language [IDL] and related conventions.) While higher-level classes in MFC make it easier to build COM components, you'll have to do most of the work yourself if you're building lightweight ATL controls. The authors cover such ATL topics as event handling (with connection points), automation and error handling, and properties and persistence for ATL-based components. They use plenty of short, effective code examples throughout this tutorial to illustrate key concepts.

The book closes with an example of Internet Explorer ATL controls (which are leaner) and "full" controls (which can be reused in such applications as Visual Basic). The world of ATL development is rough terrain, but the team of authors here succeeds in explaining a difficult subject clearly. --Rich Dragan