James Kovacs' Weblog

My MSDN Magazine article entitled Debug Leaky Apps: Identify and Prevent Memory Leaks in Managed Code has been published in the January 2007 issue. Go check it out!

Due to space constraints, the editors at MSDN Magazine left a few acknowledgements on the cutting room floor. I would like to acknowledge Rico Mariani (MS) for coining the term “midlife crisis” as it applies to the garbage collector. His blog is full of excellent perf advice and insight. I would also like to acknowledge Tess Ferrandez (MS) as one of the examples in the article is based on her blog post, “Does Page.Cache leak memory?“.

Finally, a very special thanks to my spouse, Risa Kawchuk, for her patience and excellent editing of the many versions of the manuscript.

There are many paths to software enlightenment, to attaining the state of development nirvana knows as ZenBoo. Masters of the art of ZenBoo can invert dependencies at will, value coding to interface* not implementation, favour composition over inheritance,** and respect the open-closed principle.***

On your journey to becoming a ZenBoodist, you will encounter many revelations and wonders. While meditating on test-driven development (TDD), you will gain deeper understanding of the technique. First you will realize the power of an automated test harness and a suite of regression tests that prevent bugs from finding their way into your code base. Next you will realize that your suite of unit tests allows you to confidently refactor your code base. Finally you will discover the power of mocking and realize that TDD is not a testing technique, but an agile design technique. Other wonders abound including better layered architectures, O/R mapping, IoC containers, and more.

How can I achieve a state of ZenBoo, you might ask? Everyone’s path is different, but I offer you a few humble suggestions. You must first understand object-oriented design. Just understanding object-oriented programming isn’t enough. You have to know how to design object-oriented hierarchies through responsibility assignment. Which object/class is responsible for X? By assigning responsibility for X to this object/class, how does that affect my coupling, cohesion, and a myriad of other factors? A good treatise on the subject is Applying UML and Patterns: An Introduction to Object-Oriented Analysis and Design and Iterative Development (3rd Edition) by Craig Larman.

By understanding responsibility assignment, software patterns suddenly make sense. You have a framework upon which to understand patterns and upon which to build new ones. Everyone should read Head First Design Patterns (Head First) by Eric Freeman and Elizabeth Freeman. This book offers deep insight into the ZenBoodist mind in a playful, approachable way. Although it is written for Java developers, it is equally applicable to and comprehensible by C# developers. It covers the classic “Gang of Four” software patterns, but frames them in within actual problems so that you can see how to apply them. You understand the power of coding to interface not implementation, why we favour composition over inheritance, and how to apply the open-closed principle. If you’re going to read one software book in the next year, this should be it.

Now that you understand the “Gang of Four” patterns and the basic ZenBoodist philosophies, it is time to understand how to design real-world architectures and build real-world applications. For this, we turn to Applying Domain-Driven Design and Patterns: With Examples in C# and .NET by Jimmy Nilsson. He blends together elements of Eric Evans’ Domain-Driven Design and Martin Fowler’s Patterns of Enterprise Application Architecture to take you on a journey of discovery through TDD, mocking, O/R mappers, domain-driven design, and more.

Becoming a ZenBoodist master is a difficult journey, but one well worth it. Once you achieve development nirvana, you will code with elegance, refactor with confidence, and dream in patterns. You will also realize that you are but a humble grasshopper wanting to learn more.

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If you want to get a jumpstart on ZenBoodism, check out Jean-Paul Boodhoo‘s Nothin’ but .NET course. You get 5 days of top-notch training from a ZenBoodist master, a ReSharper 2.0 license, Martin Fowler’s Patterns of Enterprise Application Architecture, and free food. The next course is in Edmonton on February 19-23, 2007. Highly recommended.

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The following reference books are useful to have on your shelf, but you probably don’t want to read them cover-to-cover unless you’re crazy. (Yes, I’ve read all of these cover-to-cover and thoroughly enjoyed them.)

• Design Patterns: Elements of Reusable Object-Oriented Software (Addison-Wesley Professional Computing Series) by Gamma, Helm, Johnson, and Vlissides (aka The Gang of Four)
• Domain-Driven Design: Tackling Complexity in the Heart of Software by Eric Evans
• Patterns of Enterprise Application Architecture by Martin Fowler

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<footnotes>

* Interface in this context can mean abstract base class or interface. The point is not to depend on a specific type, but on a contract definition.

** Favouring composition over inheritance does not mean abandoning inheritance. True ZenBoodists combine the powers of inheritance with composition to make truly powerful object models. While inheritance is over-used, don’t under-use it either.

*** Open-closed principle: Classes should be open for extension, but closed for modification.

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Full Disclosure: The book links above are through the Amazon Affiliates program. If you buy a book through that link, I get more books from Amazon to sate my hunger for knowledge.

This post by S. Somasegar, VP of Microsoft’s Developer Division, stirred up quite a racket back in September about incompatibilities in VS2005 on Windows Vista. Now that I’ve had a chance to use VS2005 on Vista seriously for a few weeks, I can say that it’s much ado about nothing. VS2005 is a complex application. Does it run on Vista? Yes. Does it run as a limited user or a filtered administrator*? Yes. Are there problems? Yes. Are they show-stoppers? Not for the most part. Full details, including broken features, can be found here on MSDN. If you’re depending on one of these features, life sucks. For most developers, it will mean the occasional visual glitch. I’ve had this happen once and a simple refresh of the Visual Studio window resolved it.

In a way, I can understand where the DevDiv is coming from. VS2005 is in the support channel now and they’re actively working on “Orcas” or Visual Studio vNext. Orcas is the development tool designed to target Vista and .NET 3.0. You’ll notice that all the .NET 3.0 designers are CTPs. They’re works in progress and destined for Orcas as their final home. (I don’t know if VS2005-compatible versions will also be available.) The unfortunate part is that the most likely early adopters of Vista are developers and the DevDiv doesn’t have a fully-supported tool for the platform. Now that sucks. Microsoft has built mind-share by creating a fantastic platform for developers. Developers are a bit out in the cold when it comes to Vista and .NET 3.0. Imagine releasing .NET 2.0 without VS2005? On the one hand, Microsoft should have coordinated th release of Orcas with Vista. On the other hand, by the time most developers will be looking at Vista, Orcas will be released. It’s only us early adopters that need to brave the excitement of running an unsupported developer tool on the latest version of Microsoft’s flagship OS. Honestly, it’s not all that exciting. For the most part, VS2005 works as it always has with a few rough edges due to UAC.

* A filtered administrator is an administrator whose admin token has had most of its privileges stripped out and the Administrators’ group SID changed to a deny. The real admin token is kept in waiting, heavily protected, and is activated when the user clicks “Continue” on a UAC prompt. A good review of the details can be found here on Márton Anka’s weblog. He also has some good information on how to declaratively and programmatically request an elevation of privilege. (i.e. Throw up the UAC prompt.)