First steps with Windows 8 development - Build Windows 8 Apps with HTML5 and JavaScript - page 102

Windows development. An asynchronous function is a function that begins execution when invoked
but has no well-defined timeline for termination.
In other words, an asynchronous function right after launch proceeds in parallel with any
subsequent code. So a developer who needs to execute some code with the results of the
asynchronous operation now has the problem of where to place this code. The shift towards
asynchronous programming, however, is significantly mitigated by some new facilities available at
the language level. In the end, all that you, as a beginning Windows 8 developer, need to learn is
how to make a function call and how to grab its results. For former .NET developers, though, the
asynchronous nature of the WinRT API might be an issue.
Another area of the WinRT API that deserves some early thoughts is storage and file access.
In Windows Store applications, direct file access is restricted in the name of security. That doesn't
mean, however, that you cannot permanently store data in a Windows Store application. More simply,
the storage API that WinRT makes available doesn't give developers full control over the disk—as it
is always the case for classic Windows applications. To open and save documents and files, you also
have new file picker components that replace the standard common dialogs of Windows.
Note Developers of Windows Store applications find an overall programming framework
(for example, WinJS for those who chose the HTML+ JavaScript stack) that looks a lot like
the popular .NET Framework, but still has some key differences. These differences are
clear signs of the overall commitment made by Microsoft to rework and reimagine the
programming framework that Windows 8 developers deal with. As a result, some of the
classes in the WinJS library are functionally identical to .NET Framework classes; some
have only minor differences. Some other classes, instead, have a counterpart and some are
just unavailable. Finally, some new classes make their debut and, overall, they contribute
to making the developer's arsenal powerful enough to build effective and functional
applications.
The Windows Store app user interface
Far beyond functionality, what really identifies an application as a Windows Store application
is its user interface and the resulting user experience. The new user interface of Windows Store
applications is known as the Windows 8 UI. This new revolutionary user interface results from the
combination of features specific to the Windows 8 operating system with some innovative design
principles. Let's find out more.
Aspects of the Windows 8 UI
If you stop at appearances, then the Windows 8 UI guidelines are just for new Windows Store
applications and can't be adapted to Windows 7, web, and mobile apps to new Windows applications,
even if developed and run specifically for Windows 8.