Application is a class that encapsulates a Silverlight application and provides the following services:

• Application Entry Point

• Application Lifetime

• Application Management

• Application-Scoped Resources

• Unhandled Exception Detection

The entry point in a Silverlight application is the class in your application assembly that derives from Application. This class is known as the application class. When the Silverlight plug-in starts, Silverlight uses metadata in the application package to instantiate the application class. At this point, the application's lifetime starts. The lifetime of an application occurs in the following order:

• Construction (Application)

• Initialization (Startup)

• Application Running

• ...

• Application Shutting Down (initiated by user)

• Exit (Exit)

By handling the Startup event, you can retrieve and process initialization parameters from the InitParams property of the StartupEventArgs object that is passed to the Startup event handler. Initialization parameters are configured by using the initParams property of the HTML object element that is used to configure and instantiate the Silverlight plug-in.

During startup, you can also specify the main application UI to show by setting the RootVisual property.

Once an application is running, the Application object and its state can be accessed from the static Current property. The singleton pattern ensures that state managed by Application, including shared resources (Resources) and custom properties, is available from a single, application-scoped location.

XAML Usage Notes for the Application class

<Application
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
  x:Class="namespace.class"... >
  ...
</Application>

The following code example demonstrates how to use this class to merge the XAML and code-behind portions of a Page class. This code is similar to the InitializeComponent method that Visual Studio generates for the same purpose.

Visual Studio generates the InitializeComponent method when a XAML file has a build action of Page. To load a XAML file using the following example code, set its build action to Resource.

Private LayoutRoot As System.Windows.Controls.Grid

Public Sub New()
    System.Windows.Application.LoadComponent(Me, New System.Uri( _
        "/SilverlightApplication1;component/Page.xaml", _
        System.UriKind.Relative))
    Me.LayoutRoot = CType(Me.FindName("LayoutRoot"),  _
        System.Windows.Controls.Grid)
End Sub

private System.Windows.Controls.Grid LayoutRoot;

public Page()
{
    System.Windows.Application.LoadComponent(this, new System.Uri(
        "/SilverlightApplication1;component/Page.xaml", 
        System.UriKind.Relative));
    this.LayoutRoot = ((System.Windows.Controls.Grid)
        (this.FindName("LayoutRoot")));
}

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Reference

Other Resources