Extensible Application Markup Language is a declarative XML-based language
developed by Microsoft that is used for initializing 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.
XAML is used extensively in .NET Framework 3.0 & .NET Framework 4.0
technologies, particularly Windows Presentation Foundation, Silverlight,
Windows Workflow Foundation and Windows Runtime XAML Framework and Windows Store
apps. In WPF, XAML forms a user interface markup language to define UI
elements, data binding, eventing, and other features. In WF, workflows can be
defined using XAML. XAML can also be used in Silverlight applications,
Windows Phone apps and Windows Store apps.
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 like
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 like XAMLPad, or a graphical editor like
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.
Consequently, 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. Since it is strongly linked to the .NET Framework
3.0 technologies, the only fully compliant implementation at present is
Microsoft's.. Technology
A XAML file can be compiled into a .BAML file, which may be inserted as a
resource into a .NET Framework assembly. At run-time, the framework engine
extracts the .BAML file from assembly resources, parses it, and creates a
corresponding WPF visual tree or workflow.
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".
= Templates = XAML uses a specific way to define look
and feel called Templates; differing from Cascading Style Sheet syntax, it is
closer to XBL. Example
This Windows Presentation Foundation example shows the text "Hello, world!"
in the top-level XAML container called Canvas.
The schema may have to be changed to work on your computer. Using a schema
that Microsoft recommends, the example can also be
This can be integrated into a Web page if WPF is installed using XBAPs that are
compiled applications running in a sandboxed environment hosted within the
browser. Another way is to use the Silverlight plugin. The code cannot be
included directly in an HTML page; rather it must be loaded into the page
via JavaScript. If .NET 3.0 or later is installed, loose XAML files can also be
viewed on their own in a compatible Web browser in conjunction with the .NET
Framework 3.0, without the need for the Silverlight plugin. Loose XAML files are
markup-only files limited to defining the visual content to be rendered. They
are not compiled with an application. The MySilverlight.js file must contain
the code that loads the above XAML code under the MySilverlight html element.
Differences between versions of XAML There are four Microsoft main
implementations of XAML: The Windows Presentation Foundation
version, which is used for the .NET Framework beginning with .NET Framework
3.0 The Silverlight 3 version
The Silverlight 4 version The Windows 8 XAML/Jupiter version
These versions have some differences in the parsing behavior.
Additionally, the XAML parsing between Silverlight 3 and Silverlight 4 is not
100% backward compatible; XAML files which are accepted by Silverlight 3 may
not be accepted or parsed differently in Silverlight 4.
Criticism The European Committee for Interoperable
Systems said in 2007 that Microsoft's use of XAML in its Silverlight product
aimed to introduce content on the World Wide Web that could only be accessed
from the Windows platform. Using a plugin, XAML is viewable in some
non-Microsoft browsers on Windows, Linux, and Mac; and Microsoft supported
Novell's Silverlight viewer for GNU/Linux called Moonlight. As of
January 2010, Moonlight 2 was compatible with Silverlight 2, but development of
Moonlight was later discontinued. See also
Comparison of user interface markup languages
EMML JavaFX
Layout manager List of user interface markup languages
NextStep/Cocoa Interface Builder Open XML Paper Specification
ZUML XUL
References External links
XAML services XAML overview
XAML reference: System.Windows.Markup Namespace and System.Xaml Namespace.