This post originated from an RSS feed registered with .NET Buzz by Ashish Shetty. Original Post: How to pass initialization params to a Silverlight 2 app Feed Title: Even a chimp can write code Feed URL: http://nerddawg.blogspot.com/rss.xml Feed Description: Ideas on software and elsewhere by Ashish Shetty: erstwhile chimp and occasional re-inventor of the wheel. Latest .NET Buzz Posts Latest .NET Buzz Posts by Ashish Shetty Latest Posts From Even a chimp can write code

This is something of an FAQ on our internal discussion lists, so I figured it merited a post.

Step 1: Declare the initParams param on the Silverlight plug-in and pass in a comma-delimited set of key-value pair tokens. For e.g. "key1=value1,key2=value2,key3=value3".

<object type="application/x-silverlight"
        width="100%" height="100%">

  <param name="source"
         value="ClientBin/SLInitParams.xap"/>

<!-- startPage key can have values Page1 or Page2 -->

  <param name="initParams"
         value="startPage=Page1" />

</object>

For best results, the key and value tokens in the initParams string must be restricted to alphanumeric values. There currently isn't support for escaping equality signs or commas, for instance, should they exist in the key or value part of the token.

Step 2: In the Application's Startup event handler, extract the initialization parameters via StartupEventArgs.InitParams property. You'll get an IDictionary<string, string>.

// Contents of App.xaml.cs

private void Application_Startup(object sender,
                                   StartupEventArgs e)

{
    string startPage = e.InitParams["startPage"];
    if (startPage != null && startPage.Equals("Page1"))

    {
       // Load Page1
       this.RootVisual = new Page();
    }
    else
    {
       // Load Page2
       this.RootVisual = new AlternatePage();
    }
}

Simple, huh? I have a sample project on how to pass initialization params to a Silverlight 2 app, and conditionally show UI, up on my sky drive.