Today, Scott Guthrie announced that Microsoft is open sourcing .NET. This is a momentous occasion, and one that I have advocated for many years.
.NET is being open sourced under the MIT license. Not only is the code being released under this very permissive license, but Microsoft is providing a patent promise to ensure that .NET will get the adoption it deserves.
The code is being hosted at the .NET Foundation's github repository.
This patent promise addresses the historical concerns that the open source, Unix and free software communities have raised over the years.
There are three components being open sourced: the .NET Framework Libraries, .NET Core Framework Libraries and the RyuJit VM. More details below.
.NET Framework Class Libraries
These are the class libraries that power the .NET framework as it ships on windows. The ones that Mono has historically implemented in an open source fashion.
The code is available today from http://github.com/Microsoft/referencesource. Mono will be able to use as much a it wants from this project.
We have a project underway that already does this. We are replacing chunks of Mono code that was either incomplete, buggy, or not as fully featured as it should be with Microsoft's code.
Read more: Personal blog of Miguel de Icaza