Windows Runtime

Windows Runtime, or WinRT, is a platform-homogeneous application architecture first introduced in Windows Server 2012 in September 2012. WinRT supports development in C++/CX (Component Extensions, a language based on C++) and the managed code languages C# and VB.NET, as well as JavaScript and TypeScript. WinRT applications natively support both the x86 and ARM architectures, and also run inside a sandboxed environment to allow for greater security and stability. WinRT components are designed with interoperability between multiple languages and APIs in mind, including native, managed and scripting languages.

Windows Phone 8.1 uses a version of the Windows Runtime known as the Windows Phone Runtime. It enables app development in C#, VB.NET and development of Windows Runtime components in C++/CX.

Technology

WinRT is implemented in the C++ programming language and is object-oriented by design. (Its predecessor, Win32 API is written mostly in the C programming language.) It is an unmanaged application programming interface (API) based on Component Object Model (COM) that allows interfacing from multiple languages, just as COM does. The API definitions, however, are stored in ".winmd" files, which are encoded in ECMA 335 metadata format, the same format that .NET Framework uses with a few modifications. This common metadata format allows for significantly less overhead when invoking WinRT from .NET applications compared to P/Invoke, and much simpler syntax.