Introduction
When you are making a web request from a Silverlight application the cookies associated with the current browser-server session are automatically sent within each request.
A common scenario is when you have a web site with some kind of a cookie driven authentication implemented and a Silverlight application within your web site that shows different content depending on whether the user is logged in or not. The Silverlight application may use some resources on the server, which are accessible only to authenticated users. The good thing is that if you are logged in the web site and make requests from the Silverlight application the server “knows” that your requests come from an authenticated user. You do not need to login both on the web site and the Silverlight application.
Example
I made a simple example to test if all this stuff really works. I just want to have a simple web site with Form authentication and a Silverlight application which uses a resource from the server. The resource behaves differently when the user is logged in and when not. I won’t describe how I created the web site and the authentication system because you are not limited about the server technology. Currently it is ASP.NET web site with the standard ASP.NET membership. But you can also make it with PHP for example.