So you started using Silverlight and you wanted to download a RSS feed, talk to a web service or download a few images from a website to realize that many of the requests you made come back to you empty or you get the 404 error. How do I get the error when I know that web page or image is there?

There are 2 methods in Silverlight to make HTTP requests to a server, both methods WebClient and HttpWebRequest check at the destination domain for the file crossdomain.xml

WebClient webClient = new WebClient(); webClient.DownloadStringCompleted += new DownloadStringCompletedEventHandler(this.Downloaded); webClient.DownloadStringAsync(Uri);

and …

HttpWebRequest request = (HttpWebRequest)HttpWebRequest.Create(Uri); request.BeginGetResponse(new AsyncCallback(ReadCallback), request); 

There is no a restriction on the browser that prevents Silverlight to do a cross domain request, I do not know why Microsoft still keeps that restriction from the Silverlight plugin as just makes the developer having to create a server side proxy in each application to accomplish those requests.

<%@ WebHandler Language="C#" Class="SilverlightProxy" %> using System; using System.Web; public class SilverlightProxy : IHttpHandler { public void ProcessRequest (HttpContext context) { string url = context.Request.QueryString[0]; System.Net.WebRequest req = System.Net.WebRequest.Create(new Uri(url)); req.Method = context.Request.HttpMethod; if (context.Request.InputStream.Length > 0) { byte[] bytes = new byte[context.Request.InputStream.Length]; context.Request.InputStream.Read(bytes, 0, (int)context.Request.InputStream.Length); req.ContentLength = bytes.Length; req.ContentType = "application/x-www-form-urlencoded"; System.IO.Stream outputStream = req.GetRequestStream(); outputStream.Write(bytes, 0, bytes.Length); outputStream.Close(); } System.Net.WebResponse response = req.GetResponse(); context.Response.ContentType = response.ContentType; System.IO.StreamReader stream = new System.IO.StreamReader(response.GetResponseStream()); // Text responses if (response.ContentType.Contains("text")) { string textResponse = stream.ReadToEnd(); context.Response.Write(textResponse); } else { byte[] bResponse = new byte[response.ContentLength]; stream.BaseStream.Read(bResponse, 0, (int)response.ContentLength); context.Response.BinaryWrite(bResponse); } context.Response.Flush(); context.Response.End(); } public bool IsReusable { get { return false; } } }

Download the Silverlight proxy here

All your request that are cross domain will have to call the silverlightProxy.ashx file before: SilverlightProxy.ashx?http://silverlightme.net/al.jpg

Flex also work in the same way, is that why Microsoft design it that way? I would think that having socket support from the Silverlight plugin, you would be able to create a socket to a server in TCP IP instead of using HTTP as the protocol.

Cheers

Al