Silverlight: Access REST service behind forms authentication site

I am new to Si开发者_C百科lverlight, and I building a simple app which provides an interface for an expense report portal. The portal has a REST API which I can access; I know I can do it using WebClient or WebHttpRequest. However, to be able to access the API, I need to login first. The login is simple forms authentication on login.aspx of the site. How do I login (post to the login page) from Silverlight?

NOTE: The site has the clientaccesspolicy.xml setup, and I am able to access the REST URL that do not require you to be logged on.

Have you looked at the Silverlight Business Application project template and WCF Ria Services. The template has built in functionality to login to a forms authenticated website.

You can use this as a starting point for your silverlight application or simply use it to see how to perform authentication from silverlight.