Microsoft this week announced it was opening up the source code to the next version of its .NET Framework, a set of developer libraries used by so-called managed code applications written in languages like C# and Visual Basic. The .NET Framework 3.5 will be licensed under the Microsoft Reference License, which gives developers the right to view but not modify the source code. Microsoft says this will give developers a better understanding of how the system works.

"You'll be able to download the .NET Framework source libraries via a standalone install, allowing you to use any text editor to browse it locally," Scott Guthrie, a general manager in Microsoft's Developer division, wrote in a recent blog post. "We will also provide integrated debugging support of it within Visual Studio 2008."

Guthrie notes that the source code for the .NET Framework 3.5 will be made available over time, beginning with core components as the .NET Base Class Libraries, ASP .NET, Windows Forms, ADO .NET, XML, and Windows Presentation Foundation (WPF). Then, he adds, the company will release the code to more libraries, including those for Windows Communication Foundation (WCF), Windows Workflow, and LINQ (Language Integrated Query), the latter of which is new to upcoming products like Visual Studio 2008 and SQL Server 2008.

This week's announcement is the latest in a long string of Microsoft efforts at promoting source code sharing, albeit on a more restrictive scale than is possible with open source products like Linux. The company also makes the source code to its Windows CE platform, the basis for Windows Mobile and other products, available via its Shared Source program.