Question

If you run this code it will throw a WebException. The inner exception is “Content-Length or Chunked Encoding cannot be set for an operation that does not write data.” and I do not understand the nature of the problem. Can anyone cast light into this dark corner?

using System.Diagnostics;
using System.Net;
using System.Text;

namespace sandpit
{
  static class Program
  {
    static void Main()
    {
      string INITIAL_URI = "http://docs.live.net/SkyDocsService.svc";
      string SOAP = "<s:Envelope xmlns:s=\"http://schemas.xmlsoap.org/soap/envelope/\"><s:Body><GetWebAccountInfoRequest xmlns:xsi=\"http://www.w3.org/2001/XMLSchema-instance\" xmlns:xsd=\"http://www.w3.org/2001/XMLSchema\" xmlns=\"http://schemas.microsoft.com/clouddocuments\"><BaseRequest><ClientAppId>SkyDrive Service Client</ClientAppId><Market>en-US</Market><SkyDocsServiceVersion>v1.0</SkyDocsServiceVersion></BaseRequest><GetReadWriteLibrariesOnly>false</GetReadWriteLibrariesOnly></GetWebAccountInfoRequest></s:Body></s:Envelope>";
      using (WebClient wc = new WebClient())
      {
        wc.Encoding = Encoding.UTF8;
        wc.Headers["SOAPAction"] = "GetWebAccountInfo";
        wc.Headers["Accept-Language"] = "en-US";
        wc.Headers["Accept"] = "text/xml";
        wc.Headers["Content-Type"] = "text/xml; charset=utf-8";
        string response = wc.UploadString(INITIAL_URI, SOAP);
        Debug.WriteLine(response);
      }
    }
  }
}

Answer 1

The problem is redirection by the webserver.

Unfortunately you have to subclass WebClient to fix this. This is harder than it looks because Silverlight (any flavour) doesn’t like this and throws an inheritance related exception until you guess that you need to override the ctor and attribute it as SecurityCritical.

public class WebClient2 : WebClient
{
  [SecurityCritical]
  public WebClient2() : base() { }  
  protected override WebRequest GetWebRequest(System.Uri address)
  {
    var wr = base.GetWebRequest(address);
    if (wr is HttpWebRequest)
      (wr as HttpWebRequest).AllowAutoRedirect = false;
    return wr;
  }
}

If you want to go further you could surface an AllowAutoRedirect property on WebClient2 and hook it all up.