Microsoft Ships .NET Core RC2, ASP.NET Core RC2

Microsoft announced the release of .NET Core RC2 featuring new APIs, performance and reliability improvements, and a new set of tools.

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Building on its strategy of taking .NET open-source and cross-platform, Microsoft this week improved the platform by delivering .NET Core Release Candidate 2, which features several enhancements over the previous release. Microsoft also released ASP.NET Core RC2.

Developers can use .NET Core RC2 to build ASP.NET Core, console apps and class libraries for Windows, Mac OS X and Linux.

"RC2 is a major update from the November RC1 release, including new APIs, performance and reliability improvements and a new set of tools," said Rich Lander, a Microsoft program manager, in a blog post on the new release.

.NET Core RC2 can be used with a variety of editors and integrated development environments, including Visual Studio 2015 Update 2, Visual Studio Code with the C# extension and soon on OmniSharp-enabled editors.

"We made major changes to the .NET Core SDK, formerly called DNX, since RC1," Lander said. "These changes were fairly significant, and we plan to make additional changes before the final release of the SDK. As a result, we opted to call the SDK a preview release."

Developers can install .NET Core SDK 1.0 Preview now—including .NET Core RC2, on Windows, OS X and Linux. They also can use it with Docker.

"When Microsoft open sourced the .NET Framework in 2014 and released runtimes for Linux in November last year, we knew interesting things were going to happen," said Mano Marks, director of developer relations at Docker, in a blog post. "Microsoft announced the second Release Candidate for .NET Core CLR. To celebrate, we took a look at using .NET Core with Docker and also released the new version of Visual Studio Tools for Docker. Turns out Microsoft is doing some interesting stuff."

Marks said Visual Studio Tools for Docker allows you to easily add Docker support for a project you're working on in Visual Studio.

"This allows you to CTRL-F5 to run your Docker app directly in Visual Studio," he said. "What the new version offers that's pretty awesome is breakpoint debugging. That's right, you get breakpoint debugging from Visual Studio with your code running in a container."

Both .NET Core and ASP.NET Core have improved significantly since RC1, with improved performance and reliability. .NET Core RC2 is a "Go Live" release, which means you can use it in production and Microsoft will provide support.

.NET Core is supported on Windows, OS X and Linux, including Red Hat Enterprise Linux 7.2, Centos 7.1, Debian 8.2 and above, Ubuntu 14.04, Linux Mint 17 and above, OS X 10.11, Windows 7 and above, Windows Server 2012 R2 and above, and Windows Nano Server TP5.

Microsoft added more than 1,000 new APIs in .NET Core RC2, Lander said. The company also made major improvements to the just-in-time (JIT) compiler, including upgraded garbage collection, a new .NET Standard Library and new telemetry tools to collect usage information about the .NET Core Tools.

The new ASP.NET release features the rebranding of ASP.NET 5 to ASP.NET Core, said Jeff Fritz, program manager for the .NET Developer Outreach Team, in a blog post. "This renaming was made in order to clarify that this is a new framework built from the ground up and not a revision of the existing ASP.NET frameworks."

A key change that occurred between RC1 and RC2 is the introduction of the .NET command-line interface, he said.

Microsoft also announced updated Web development tools. The ASP.NET Core Tooling Preview release supports the .NET Core RC2 and ASP.NET Core RC2 releases.

"With this release, we're splitting the delivery of the Visual Studio tools from the ASP.NET Core and .NET Core runtime and libraries," Fritz said. "Those frameworks are almost ready for RTM, and we are working on delivering the advanced capabilities for building and managing applications built with these new tools."