Since early this decade, Microsoft has been promoting their software framework, the .NET platform and its associated libraries. Now up to incarnation v3.5, Windows developers worldwide have rejoiced at the framework source code finally being made available. Yet, does this reflect any trend towards open source by the Redmond giant? How generous is the license and what does it mean?

Some background: previous versions of Windows have consisted of a bundled set of libraries, known as the application programmer interface – or API. To differentiate it, the first 32-bit libraries became known as the Win32 interface and the previous Windows 3.1 16-bit APIs were retrospectively titled Win16.

Yet, by the end of the last millennium Microsoft decided the burden of providing backwards compatibility hampered their freedom to innovate and deliver a modern programming milieu. Consequently, the .NET framework was birthed which essentially provides a runtime environment with a rich suite of functions and features. It sits atop the Windows framework itself and interprets .NET programs, fundamentally converting instructions at runtime.

The rise of a new framework necessitated the need for a new set of programming languages which would generate executable code in the right format; this then brought into being the Visual Studio.NET collection of languages – Visual Basic.NET, J# and C#, among others by other vendors. It’s now possible to find .NET versions of Delphi, Python and even COBOL.

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