Microsoft Open Sources .NET CoreCLR

The ongoing effort to open source .NET Core gets clearer, as the team adds the "execution engine" that drives .NET apps to the Github repository.

Microsoft's .NET Team said in a blog post that it has added the .NET Core Common Language Runtime repository, or .NET CoreCLR, to Github. The move is another significant step in an ongoing process to fully open source .NET that was put in motion near the beginning of 2014.

The .NET team calls .NET CoreCLR the "execution engine for .NET apps," and includes Intermediate Language byte code loading, compilation, garbage collection, native interoperability and other .NET runtime components. It currently runs only on Windows, but the general plan outlined in November is to eventually port platform-specific components for Linux and Mac.

The process of open sourcing .NET was started back in November last year starting with the .NET CoreFX repository that contains all the class libraries on Github. Even so, the team laid the groundwork much earlier in the year, with other releases to the Microsoft Codeplex open source project hosting site. ASP.NET was open sourced in March 2014, while the "Roslyn" .NET Compiler Platform was open sourced a month later. Over the last year, both projects were moved over to the more popular Github open source project hosting site.

Moving projects from Codeplex to Github from a perception standpoint appears to have made a difference in community participation. Microsoft program manager Immo Landwerth blogs of a project that he was working on that got more attention once he posted it to Github. "During the two years it was on CodePlex I've only received a single pull request." he wrote. "Five days after I moved to GitHub I already received three pull requests and found two other contributors." (Landwerth in December wrote a comprehensive blog that spells out the complexity of simplifying the fragmented .NET Framework into the more open-source-friendly and unifying .NET Core and it offers insights into the process that's worth reading.)

Because the .NET CoreCLR repository includes both C# and C++ code collections, the team said that developers will need "multiple toolsets to build both C# and C++ code, including tools that do not ship with Visual Studio." A work-in-progress developer guide that lists the tools and requirements are here for those who want to start digging in and forking projects.

Developers can find out more next month, as the team is expected to provide an update on their open source efforts at dotnetConf, a free virtual event hosted by Microsoft on March 18-19. For more info, click here.

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