Microsoft To Open .Net Source Code

The code will be released under Microsoft's "look but don't touch" Microsoft Reference License. Unlike traditional open-source licensing, Microsoft's restrictive terms only allow developers to study the covered code -- it grants no modification or redistribution rights.

Microsoft will begin by offering source code for its .Net Base Class Libraries, Windows Presentation Foundation and ASP.NET, among other software systems, with addition libraries added in later months. The code release will come with Microsoft's release of Visual Studio 2008 and .Net 3.5, expected to launch by the end of this year.

Developers will be about to download the code and browse it in any text editor. Microsoft also plans to ingrate debugging support tools using the code into Visual Studio 2008. When programmers run into errors in their application code, they'll be able to consult Microsoft's code to better understand how to develop against it.

"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 developers to build better applications and make even better use of them," Guthrie wrote in his blog.

The real impact of Microsoft's move is less in the code access itself and more in what it says about the company's changing mindset, according to developers.

Scott Bellware, a software designer for CRM maker Dovetail Software and a Microsoft-designated "MVP" for his volunteer Microsoft community-development efforts, said he doesn't expect the move to affect his own development work because existing tools like Reflector (a third-party offering) already offer effective functionality for library browsing and decompiling. But he's happy to see Microsoft moving toward giving developers greater access to its code.

"I'm more excited about where this kind of effort could lead rather than the negligible effects of the act itself," Bellware said. "This is possibly the sign of a growing cultural movement within Microsoft. It's way to early to call it a trend, but it points to a potential for a re-emergence of greatness and possibly even an embrace of integrity.

Influenced by evangelists within its developer organization, Microsoft has slowly loosened its grip on its code and made its development process more transparent.

While the company remains ideologically opposed to traditional open-source software -- free, non-proprietary applications -- it has recognized the value of the open-source world's community development approach. New products like "Orcas," the code-name for Visual Studio 2008, now develop publicly, with frequent "preview" releases of the evolving software. Meanwhile, with its CodePlex "shared source" portal, Microsoft is making more of its own source code available to the public and encouraging community development of .Net tools and applications.