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Microsoft Begins Releasing Source Code for .NET Framework Libraries

Microsoft today followed up on its earlier promise to start releasing the .NET framework library source code for .NET 3.5.

The source code for more than a dozen libraries -- including ASP.NET, Windows Presentation Layer, Windows Forms and the .NET Base Class Libraries -- are now accessible. The complete list of libraries that are now open is available here.

In his blog post today announcing the release, Scott Guthrie, general manager, Microsoft Developer Division, said that more libraries will come soon, including ones for Workflow, Windows Communication Foundation and LINQ.

"We think that enabling source code access and debugger integration of the .NET Framework libraries is going to be really valuable for .NET developers," he commented in his post. "Being able to step through and review the source should provide much better insight into how the .NET Framework libraries are implemented, and in turn enable you to build better applications and make even better use of them."

Instructions for configuring Visual Studio 2008 to access and debug the source code can be found here.

While the source code is being released under the company's read-only reference license (as originally planned), Microsoft has made a change to the license terms.

"When we announced that we were releasing the source back in October, some people had concerns about the potential impact of their viewing the source," Guthrie wrote. "To help clarify and address these concerns, we made a small change to the license...if the software you are developing is for Windows platforms, you can look at the code, even if that software has 'the same or substantially the same features or functionality' as the .NET Framework."

About the Author

Becky Nagel serves as vice president of AI for 1105 Media specializing in developing media, events and training for companies around AI and generative AI technology. She also regularly writes and reports on AI news, and is the founding editor of PureAI.com. She's the author of "ChatGPT Prompt 101 Guide for Business Users" and other popular AI resources with a real-world business perspective. She regularly speaks, writes and develops content around AI, generative AI and other business tech. She has a background in Web technology and B2B enterprise technology journalism.

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