Microsoft to open source more of .NET, and bring it to Linux, Mac OS X

Microsoft is porting its server-side .NET stack to Linux and Mac OS X, and is making more of that stack available as open source.
Written by Mary Jo Foley, Senior Contributing Editor

Microsoft is planning to open source the full server-side .NET core stack and to take that open-sourced .NET core to Linux and Mac OS X, alongside Windows.


Microsoft officials announced the company's latest .NET programming-model plans on the opening day of the Connect(); developer-focused event on November 12.

In April 2014, Microsoft announced plans to open source a number of its developer technologies, including ASP.NET, the Roslyn .NET compiler platform, the .NET Micro Framework, .NET Rx and the VB and C# programming languages. Microsoft officials said they planned to make these technologies available via a newly created .Net Foundation.

Today, the company is adding more pieces of .NET to its open-source list under the MIT open-source license, including the .NET Common Language Runtime (CLR), the just-in-time compiler, garbage collector and Base Class libraries. Microsoft also is pledging to work with partner Xamarin -- which has made .NET available on other platforms -- to "bring together the Mono runtime work and our work and converge them over time," said Soma Somasegar, the Corporate Vice President of Microsoft's Developer Division.

Microsoft will port the core server-side .NET runtime so that it runs across Windows, Linux and the Mac. This will allow developers to build ASP.NET 5.0 applications that can be deployed and run on Windows, Linux and/or Mac environments. (Microsoft is still expecting most .NET developers to deploy their server-side apps on Windows and Linux, but is providing Mac compatibility mainly for the development environment choice, officials said.)

Microsoft is using GitHub for hosting the core framework porting and open-sourcing work.

"We want to have a comprehensive and complete dev offering for folks working on any kind of application," Somasegar said.

Microsoft's next-generation server-side Web-development framework, ASP.NET 5.0, already has been shown running on Linux and OS X.

Microsoft is not planning to open source the client side .NET stack, which means it won't be open sourcing libraries specific to the client such as Windows Presentation Foundation (WPF) and Windows Forms, Somasegar confirmed. (Yes, WPF is back, and a new version of it will be part of Visual Studio 2015, due out next year, Microsoft officials have confirmed.)

Microsoft is kicking off work on these new open-sourcing and porting initiatives today, but the fruits of the work won't be available until some time in the coming months, officials said. 

Microsoft and Xamarin are annoucing a new "streamlined experience" for installing Xamarin from Visual Studio, as well as the addition of Visual Studio support to Xamarin's free Xamarin Starter Edition product. (Starter Edition is for "indie" developers with five or fewer employees who want to build iOS or Android apps using C#.)

Microsoft is not planning to open source the client side .NET stack, which means certain pieces like the Windows Presentation Foundation (WPF) and Windows Forms won't be going open source, Somasegar confirmed.

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