I’ve been writing on Credentials in context of Silverlight for some time now. I didn’t like the options that were available to secure services and allow integration with Silverlight. For some history search for “credentials” on my blog.

July 2008 – Silverlight 2 – A series of articles on possible (failed) work-arounds for getting Credentials in Silverlight.

March 2009 – Silverlight 3 – WebClient, WebRequest and WCF calls using Credentials?

July 2009 – Silverlight 3 – Did we get support for Credentials?

In Silverlight 3 we already got the property Credentials on both WebClient and WebRequest. But sadly there still was no implementation available. After the launch of Silverlight 3 Tim Heuer already commented that the feature for credentials was being considered for future versions. Very nice, specially because we finally got it in Silverlight 4 (beta).

Support for Credentials has come to the ClientHttp stack, so you must make sure you register the http prefix to be using ClientHttp stack.

WebRequest.RegisterPrefix("http://", System.Net.Browser.WebRequestCreator.ClientHttp);

Besides that we also need to make sure that we set the property UseDefaultCredentials to false. Depending on whether you make use of a WebRequest or use a WebClient it will look like this.

request.UseDefaultCredentials = false;

WebRequest with Credentials

When you want do a simple webrequest to a url that’s secured using credentials this can look like this.

private void DoWebRequestWithCredentials()
{
    WebRequest.RegisterPrefix("http://", System.Net.Browser.WebRequestCreator.ClientHttp);
    var request = WebRequest.Create(new Uri("http://mark.mymonster.nl")) as HttpWebRequest;
    request.Credentials = new NetworkCredential("username", "password");
    request.UseDefaultCredentials = false;
    request.BeginGetResponse(ResponseCallBack, request);
}

private void ResponseCallBack(IAsyncResult ar)
{
    var request = ar.AsyncState as HttpWebRequest;
    var response = request.EndGetResponse(ar) as HttpWebResponse;
    using(var reader = new StreamReader(response.GetResponseStream()))
    {
        string result = reader.ReadToEnd();
    }
}

WebClient with Credentials

The WebClient has the same properties. Works same as providing credentials to a WebRequest, that’s really nice.

private void DoWebClientDownloadWithCredentials()
{
    WebRequest.RegisterPrefix("http://", System.Net.Browser.WebRequestCreator.ClientHttp);
    var client = new WebClient();
    client.Credentials = new NetworkCredential("username", "password");
    client.UseDefaultCredentials = false;
    client.DownloadStringCompleted += new DownloadStringCompletedEventHandler(client_DownloadStringCompleted);
    client.DownloadStringAsync(new Uri("http://mark.mymonster.nl"));
}

private void client_DownloadStringCompleted(object sender, DownloadStringCompletedEventArgs e)
{
    string result = e.Result;
}

WCF?

Sadly during tryout I didn’t find the credentials property to be part of ClientBase<T>. So for WCF we still have to wait some time to get credentials, or will it be part of final Silverlight 4?

What happens when you provide the wrong credentials?

I tried to make a webrequest with the wrong credentials. I expected an exception similar to “Unauthorized”, but instead I received a WebException with the message “The remote server returned an error: NotFound.”. I hope the team changes this to a more meaning full exception, because this makes debugging very hard.