COM and .NET Interoperability (Paperback)

~ Andrew Troelsen (Author)
Key Phrases: car library, legacy components, creation timeout, Visual Basic, Windows Forms, Private Sub (more...)

Editorial Reviews

Amazon.com Review

Aimed at the more experienced developer who needs to get the old and the new in Windows to coexist, COM and .NET Interoperability gives you all the nitty-gritty detail to get .NET Framework code and the older COM standard to work together effectively. Crammed with technical knowledge and a wide range of programming techniques you most likely won't find anywhere else, this book will fill a worthwhile niche as corporations move older Windows code to .NET.

The in-depth technical detail of the inner workings of both COM and .NET sets it apart. It says a lot about this title that it is only after 300 pages of introductory material on the inner workings of COM and .NET that the text turns to interoperability between the two. First comes a traditional tour of COM components, including all the gnarly details of Iunknown, GUIDs, type libraries, late binding (and Idispatch), and deployment through the registry. A short section looks at using the Active Template Library (ATL) and its wizards to simplify "traditional" COM components.

The author also examines how to build and deploy equivalent components in .NET, along with some more advanced material on reflection, generating on-the-fly code, and assembly information. Material on emulating late-binding in .NET is also a standout here, as this technique is not obvious under the new Windows.

At the heart of this book are six chapters showing how to get .NET to call COM code and vice versa, organized into beginning, intermediate, and advanced techniques for each. Core material here shows how to invoke COM objects within .NET, as well as ActiveX controls, a worthy addition, as this is likely to be a workable strategy for .NET developers for years to come. Advanced techniques range further afield. When it comes to calling .NET code from older COM code, apart from the basics of invoking .NET from within "traditional" C++ and Visual Basic, the author also shows how to "consume" new .NET classes like collections within COM.

Final sections turn toward other COM+ services, with a full tour of transactions and just-in-time activation (JITA) for building more scalable Windows components. (Here, besides "classic" COM+ components in C++, the author shows how to do it in .NET.) The book rounds out with examples of "fully serviced" Windows components in .NET, including a solid example using a Web service.

While COM is destined to wither away, for the next few years there will be ample opportunity for advanced programmers to leverage an in-depth knowledge of COM and .NET. This book's authoritative treatment of most every conceivable permutation of COM and .NET code interaction makes it the definitive resource on the subject. Armed with this title, any advanced C++/C# developer will be able to mix in old code and new code effectively. --Richard Dragan

Topics covered: Introduction to Platform Invocation (PInvoke) services; calling a traditional DLL from C and C++; using PInvoke to call a traditional DLL with .NET; callback functions in .NET for DLLs; tutorial for COM servers (conventions and built-in interfaces, GUIDs, class factories, deployment); C++ COM clients; IDispatch and scriptable objects; Active Template Library (ATL) basics (including wizard support); COM servers in VB 6; COM IDL files in detail (type libraries and programming reading type info); using C# to view COM type libraries; .NET servers (including assemblies and deployment options); advanced techniques for on-the-fly code generation with the System.CodeDOM APIs; .NET types explained; using .NET reflection APIs (viewing type info in C#); late binding in .NET; basic .NET to COM interoperability (converting COM IDL to .NET types); deploying Interop assemblies; intermediate techniques (including using COM Variants, Param arrays, structures and collections between platforms, events and delegates, error handling); advanced techniques (COM classes implementing .NET interfaces); consuming ActiveX controls in .NET code; modifying Interop assemblies; basic COM to .NET code-sharing techniques (including the COM Callable Wrapper, CCW, the tlbexp.exe utility, COM-aware .NET types); consuming .NET components in VB 6, C++, and VBScript; intermediate COM to .NET techniques (using .NET enumerated types, structures, delegates, and collections within COM); advanced techniques for using .NET in COM (changing type marshaling, custom COM interfaces, defining COM interfaces using managed code, manually defining COM atoms in C#, custom hosts for the .NET runtime); overview of COM+ (including the transactions, pooling, and the COM+ Catalog); classic COM+ components versus .NET equivalentsp; lazy automatic registration; object construction strings; just-in-time activation (JITA); transactional programming in .NET; and sample serviced components (including a Web service example).

Product Description

<p><i>COM and .NET Interoperability</i> provides a complete overview of the process of building .NET applications that interact (interoperate) with existing COM code. Before digging into that critical topic, author Andrew Troelsen offers a concise overview of the COM architecture and provides examples using various COM frameworks (C++, ATL, and VB 6.0) as well as the core .NET managed languages (C# and VB .NET). </p>

<p>After covering the preliminaries, the book explores numerous issues that arise in interoperability, including interacting with the Win32 API, dynamically generating source code via System.CodeDOM, creating serviced (COM+) components using managed code, manually editing (and recompiling) .NET metadata, and the process of constructing custom COM/.NET conversion utilities. Both intermediate and advanced developers will welcome the practical information they need to quickly work with COM and COM+ in .NET applications, and learn how to create .NET components that are COM compatible. </p>

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Product Details

• Paperback: 769 pages
• Publisher: Apress; 1st edition (April 20, 2002)
• Language: English
• ISBN-10: 1590590112
• ISBN-13: 978-1590590119
• Product Dimensions: 9 x 7.4 x 1.8 inches
• Shipping Weight: 2.9 pounds (View shipping rates and policies)
• Average Customer Review: 4.5 out of 5 stars  See all reviews (6 customer reviews)
• Amazon.com Sales Rank: #856,015 in Books (See Bestsellers in Books)

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Customer Reviews

Most Helpful Customer Reviews

10 of 12 people found the following review helpful:

5.0 out of 5 stars A Must Read for Anyone doing Interop Programming, July 23, 2002

By	Richard Hertzberg, PKC Corporation (Burlington, Vermont USA) - See all my reviews

Like Andrew's "C# and the .NET Platform", this book combines an excellent technical overview with nitty gritty examples that detail how to use these technologies in your own development. We followed the book's step-by-step instructions to create a CCW that allows us to use the NET framework's XML digital signature support in our existing unmanaged code. Try cobbling up an XMLDSIG implementation on your own! I can't imagine anyone attempting to use Interop technology without a reference like this.

3 of 3 people found the following review helpful:

4.0 out of 5 stars From COM to .NET and Back Again, December 21, 2004

By	Jeffrey Heaton "Jeff Heaton" (St. Louis, MO) - See all my reviews

There may be times when you need to access legacy COM DLL's written in non-managed C++ or Visual Basic. This may be as a stop-gap measure until your older legacy code can be updated to .NET. In cases where performance is critical, you may have no desire to ever upgrade your C++ DLL, but would like to use C# for GUI design, rather than Microsoft Foundation Classes. If any of these situations apply, this is the book for you.

This book begins with a few chapters that will bring the reader up to date on both sides of the GAP. First you are shown the fundamentals of COM objects. Second you are shown the newer .NET architecture. Only by understanding both sides will you be able to make the two effectively communicate. For experienced users, who are already familiar with COM and .NET this section can easily be skipped. The book then continues with an overview of what datatypes are available on each side, and how they cross over.

The real meat of the book comes in the next two sections. Three chapters (the basics, intermediate and advanced topics) are given first for COM to .NET. Then the exact same pattern is repeated from .NET to COM. I spent most of my time with the .NET to COM part of the book, as I was using a C++ DLL with C#. The book answered all of my questions and I was able to successfully implement the application.

The book provides a great deal of good information, but it is sometimes hard to find exactly what you are looking for. Each direction is covered in chapters named the basics, intermediate and advanced topics. What exactly is meant by this is not clear until you begin the chapter. I often found myself skimming all three sections trying to find an example close to what I was doing.

2 of 3 people found the following review helpful:

3.0 out of 5 stars Programmer traps missing, April 14, 2004

By A Customer

This book is definitely a good starting point. It covers most of the topics, a newcomer would like to see and enables both, the .NET programmer and the COM programmer (which is most likely a VB programmer) to find a way into the material.
What is missing from my point of view is a section which describes the problems that a typical user/writer of legacy code (which COM definitely is from Microsoft's perspective) will have to overcome before he can reuse COM components in the .NET framework and write COM-usable components within .NET.
Here it relies a bit to much on Microsoft's perspective, which is that "the Framework" will do everything for you.
This is however only partly true and many programmers have gone through hard times.
When you start with COM interop, it all seems to easy... but be assured, Microsoft has a lot of work to do for programmers to make it work seamlessly.