You construct a Windows Store app using several language combinations, typically a language pair. A pair of languages is needed because the application code consists of both front-end and back-end components. The front-end (display) component is defined using a declarative language like XAML or HTML5; the back end (execution logic) executes in a procedural (or object-oriented) language such as C# or C++.
In concert with the arrival of Windows 8, .Net is being updated to version 4.5. Here, Visual Studio 2012 supports the new "async code" constructs in C# and VB.Net, which require new syntax elements in the languages and define new behaviors. Using the async and await keywords, you can identify potentially long-running methods -- that is, methods that may be blocked waiting for an I/O response -- but permit other parts of your code to continue executing, unimpeded by the blocked methods. Asynchronicity is key in Windows 8 apps. The Windows 8 application model is geared toward responsiveness, and many of the Windows 8 runtime APIs only support asynchronous operations.
When you define an async method, you're specifying that the method's results will be available at some unknown time in the future. The calling code can continue to execute, until it reaches a point where it must use the async method's return value. You identify this point with the await keyword. An async method returns a Task object, which encapsulates the rendezvous point (used by await) and provides access to the method's return value. In essence, the async and await keywords provide multithreading without your having to write callback functions, or thread startup and teardown code.
Not only does Visual Studio 2012 recognize the new async keywords, the IDE's debugger is also async-aware. You can debug an application as though the otherwise asynchronous code executed synchronously.
Turning C++ to 11