Question

Problem:
(Solution at the end)
I got a Silverlight App with-in a Web Project

Web

Silverlight

The web contains a service:

[WebService(Namespace = "svChat")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
// To allow this Web Service to be called from script, using ASP.NET AJAX, uncomment the following line.
//[System.Web.Script.Services.ScriptService]
public class GetIPService : System.Web.Services.WebService 
{

    public GetIPService () 
    {

        //Uncomment the following line if using designed components 
        //InitializeComponent(); 
    }

    [WebMethod]
    public string GetIp() 
    {
        return HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"];
        
    }
  }

And I got a class in my Silverlight App using the Service:

public class Client
{
    private string ip;
    private string created;

    #region Properties
    public string Ip
    {
        get { return ip; }
        set { ip = value; }
    }

    public string Created
    {
        get { return created; }
        set { created = value; }
    }
    #endregion

    public Client()
    {
    }

    public void SetIp()
    {
        ServiceReference1.GetIPServiceSoapClient scIpClient = new svChat.ServiceReference1.GetIPServiceSoapClient();
        scIpClient.GetIpCompleted += new EventHandler<svChat.ServiceReference1.GetIpCompletedEventArgs>(IpService_Completed);
        scIpClient.GetIpAsync();
    }

    private void IpService_Completed(object sender, ServiceReference1.GetIpCompletedEventArgs e)
    {
        this.ip = e.Result;
    }

}

After Client is created, SetIp() is called, and Client.Ip is added to a text box.
Nothing happens.
Ip = null.

Service itselfs works, tested it.
Getting Ip by the above code works.

Gettings Ip via service through Silverlight App does not work.

<configuration>
    <system.serviceModel>
        <bindings>
            <basicHttpBinding>
                <binding name="GetIPServiceSoap" maxBufferSize="2147483647" maxReceivedMessageSize="2147483647">
                    <security mode="None" />
                </binding>
            </basicHttpBinding>
        </bindings>
        <client>
            <endpoint address="http://localhost:2090/svChat.Web/GetIPService.asmx"
                binding="basicHttpBinding" bindingConfiguration="GetIPServiceSoap"
                contract="ServiceReference1.GetIPServiceSoap" name="GetIPServiceSoap" />
        </client>
    </system.serviceModel>
</configuration>

Any ideas?

regards,

Solution:
Creating a Silverlight Application within VS 2010 (Ultimate) causes VS to use the same test-server for the silverlight application and the website.
This is no problem until VS uses the Silverlight configuration to set up the test server.
The silverlight client will now not be able to correctly access the webservers webservice.
The exact reason is not known, but I think it’s caused by the above described situation.
So start debug, and wait until website is loading and "Exception" pops up, then "Stop" debugging, and continue testing the website withouth worrying about exceptions.
Disadvantage: No debugging.

Answer 1

I guess the key thing is to confirm that the request to the Web Service does include the Http header HTTP_X_FORWARDED_FOR which is normally added by a proxy server or load balancer.

If this header does not exist then the result of the call to

HttpContext.Current.Request.ServerVariables["HTTP_X_FORWARDED_FOR"]; 

is null, which is what you are seeing. Since the end point you are showing in the configuration points to localhost, you are definately not going through a proxy or a load balancer so there would not be a HTTP_X_FORWARDED_FOR header added.

http://localhost:2090/svChat.Web/GetIPService.asmx

If you are not going through a proxy or load balancer you can look use REMOTE_ADDR (with varying degree of success)

HttpContext.Current.Request.ServerVariables["REMOTE_ADDR"]

Regardless, you should probably write your code to handle the fact that neither of these might actually have anything set. You cannot assume every proxy or lad balancer will add the HTTP_X_FORWARDED_FOR header, unless you controll all infrastrucutre components between the client and the server.

Update: Based on the code you provided, here are the changes I made.

    public MainPage()
    {
        InitializeComponent();
        this.Loaded += new RoutedEventHandler(Page_Loaded);
        this.MainClient = new Client();
        ClientList.Clients.Add(this.MainClient);

        // Removed LoadXMLFile call here, constructor runs before Loaded event.
        //LoadXMLFile();
    }

    private void Page_Loaded(object sender, RoutedEventArgs e)
    {
        svChat.ServiceReference1.GetIPServiceSoapClient scIpClient = new svChat.ServiceReference1.GetIPServiceSoapClient();
        scIpClient.GetIpCompleted += new EventHandler<svChat.ServiceReference1.GetIpCompletedEventArgs>(IpService_Completed);

        scIpClient.GetIpAsync();
    }

    public void IpService_Completed(object sender, svChat.ServiceReference1.GetIpCompletedEventArgs e)
    {
        this.MainClient.Ip = e.Result;
        // Probably where you should call LoadXMLFile
        // at this point the async call has returned and 
        // the ip is intitialized.
        LoadXMLFile();
    }