Understanding COM: Ancient Technology in Modern Times

Publishing a new book about COM may seem an odd choice in this day and age where .NET is ubiquitous and many new technologies exist to make the lives of developers easier. Yet any Windows system still uses thousands of COM objects and countless interfaces, and many enterprise applications still have a strong COM based foundation.

The last meaningful COM related book was written about 2 decades ago. Since then, Windows 64 bit became mainstream, security was tightened, UAC was invented, and so on. At the same time, the C++ standard changed, compilers changed, runtime libraries changed and COM features were added and dropped. However, none of these changes were ever properly explained as 1 consistent whole.

This book aims to be that source of COM related information in the modern day, explaining things from the ground up in such a way that readers of any experience level can understand how the various pieces all fit together and how the original design principles were kept intact in a changing digital landscape. This book also sheds some light on things that no longer exist or have the same relevance, but which were referenced in older books and of which traces can still be seen in Visual Studio.

The first section of the book starts out with the historical context in which COM was created, explaining the various problems and restrictions that guided the design decisions for COM. From there, the book explains core terminology and concepts, the different ways to implement and use a COM server, and topics such as marshaling, aggregation and dispatching. The second part of the book explains how to use the Microsoft ATL framework, as well as topics such as asynchronous programming, connection points and inter-operability with the .NET Framework. The third and final part of the book covers the DCOM security model and various miscellaneous topics.

Overall, 'Understanding COM' aims to be an authoritative source of information for COM in the modern world of software development, in the same way that 'Essential COM' was that source of information in the early 2000's.