Extensible Application Markup Language (XAML, pronounced zammel [??z??m????]) is a declarative XML-based language created by Microsoft which is used to initialize structured values and objects. It is available under Microsoft's Open Specification Promise.The acronym originally stood for Extensible Avalon Markup Language - Avalon being the code-name for Windows Presentation Foundation (WPF).
XAML is used extensively in .NET Framework 3.0 technologies, particularly Windows Presentation Foundation, Silverlight, and Windows Workflow Foundation (WF). In WPF, XAML is used as a user interface markup language to define UI elements, data binding, eventing, and other features. In WF, workflows can be defined using XAML.
XAML elements map directly to Common Language Runtime object instances, while XAML attributes map to Common Language Runtime properties and events on those objects. XAML files can be created and edited with visual design tools such as Microsoft Expression Blend, Microsoft Visual Studio, and the hostable Windows Workflow Foundation visual designer. They can also be created and edited with a standard text editor, a code editor such as XAMLPad, or a graphical editor such as Vector Architect.
Anything that is created or implemented in XAML can be expressed using a more traditional .NET language, such as C# or Visual Basic.NET. However, a key aspect of the technology is the reduced complexity needed for tools to process XAML, because it is based on XML. As a result, a variety of products are emerging, particularly in the WPF space, which create XAML-based applications. As XAML is simply based on XML, developers and designers are able to share and edit content freely amongst themselves without requiring compilation. As it is strongly linked to the .NET Framework 3.0 technologies, the only fully compliant implementation as of today is Microsoft's.
When used in Windows Presentation Foundation, XAML is used to describe visual user interfaces. WPF allows for the definition of both 2D and 3D objects, rotations, animations, and a variety of other effects and features.
When used in Windows Workflow Foundation contexts, XAML is used to describe potentially long-running declarative logic, such as those created by process modeling tools and rules systems. The serialization format for workflows was previously called XOML, to differentiate it from UI markup use of XAML, but now they are no longer distinguished. However, the file extension for files containing the workflow markup is still "XOML".
XAML uses a specific way to define look and feel called Templates, different from the Cascading Style Sheets syntax, but closer to XBL.
This Windows Presentation Foundation example shows the text "Hello World!" in the top-level XAML container called Canvas.
The schema (the xmlns="http://schemas.microsoft.com..." part) may have to be changed to work on your computer. Using a schema that Microsoft recommends, the example can also be
<div id="MySilverlight" >
The MySilverlight.js file must contain the code that loads the above XAML code (as an XML file) under the MySilverlight html element.
The European Committee for Interoperable Systems argues that Microsoft's use of XAML in its Silverlight product aims to introduce content on the World Wide Web that can only be served from the Windows platform.
However, using a plugin, XAML is viewable in some non-Microsoft browsers on Windows and Mac, and Microsoft provides direct support for the development of a Silverlight viewer for GNU/Linux called Moonlight. As of April 2009, Moonlight implements only a small subset of Silverlight features