WCF 4.0 service consumed in Silverlight 4.0 avoiding cross domain problem


This article will explain how to call WCF 4.0 service hosted in IIS 7.5 in a Silverlight application. This article will explain the way to avoid cross domain problem also.

Expected Output


When user will click on + button a WCF service hosted on IIS will get called. As a input parameter to service value from two text box will be passed and result from the service will get display in result text box.


Create WCF Service

Create WCF service. Open visual studio select new project and then from WCF tab select WCF Service application to create a new WCF service.


Delete the default code created by WCF from IService1 and Service1.svc.cs

a. So delete the data contract

b. Modify the service contract as below. Just make one operation contract to return a string.


using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Web;
using System.Text;
namespace WcfService5
    public interface IService1
        string  GetMessage(string  number1 , string number2);


Now implement the service as below,


using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.Serialization;
using System.ServiceModel;
using System.ServiceModel.Web;
using System.Text;

namespace WcfService5
    public class Service1 : IService1
        public string GetMessage(string number1, string number2)
            return (Convert.ToInt32(number1) + Convert.ToInt32(number2)).ToString();

Since, we are creating WCF Service for SilverLight client, so we need to modify the endpoint of the service with basicHttpBinding.

As we know SilverLight supports either basicHttpBinding or webHttpBinding. webHttpBinding is essentially for REST based service . We are going to use basicHttpBinding to enable SOAP based WCF service for SilverLight client.

1. Declare the end point with basicHttpBinding.


2. Declare the Meta data exchange end point.


3. Define the service behavior


So the service will look like



<?xml version="1.0"?>
    <compilation debug="true" targetFramework="4.0" />
        <behavior name ="svcbh">         
          <serviceMetadata httpGetEnabled="true"/>         
          <serviceDebug includeExceptionDetailInFaults="false"/>
      <service name ="WcfService5.Service1" behaviorConfiguration ="svcbh">
        <endpoint name ="SilverLightendpoint"
                  address =""
                  binding ="basicHttpBinding"
                  contract ="WcfService5.IService1"/>
        <endpoint name ="MetaDataSilverlightEndpoint"
    <!--<serviceHostingEnvironment multipleSiteBindingsEnabled="true" />-->
    <modules runAllManagedModulesForAllRequests="true"/>

Hosting in IIS and solving the cross domain problem

Host the service in IIS. Please read here step by step to host WCF 4.0 Service in IIS 7.5

Solving cross domain problem

1. Right click on WCF Service project and add new item. Select XML file from Data tab.


2. Give the name of the XML file clientaccesspolicy.xml


3. Add the below markup in ClientAcccessPolicy.xml file


So, finally now you will have a ClientAccesspolicy.xml file in WCF project


<?xml version="1.0" encoding="utf-8" ?>
      <allow-from http-request-headers="SOAPAction,Content-Type">
        <domain uri="*" />
        <resource path="/" include-subpaths="true"/>

4. Now open WCF Service project in windows explorer. To do this right clicks on the project and select open folder in Window explorer.


Copy clientaccesspolicy.xml file and paste it in C:\inetpub\wwwroot. Make sure in wwwroot folder clientaccesspolicy.xml file exist.

Consuming in SilverLight 4.0

1. Create a Silver Light project by Project->new ->SilverLight -> SilverLight Application


And create a web site to host Silver light application.


2. Now design the page in XAML.



<UserControl x:Class="SilverlightApplication3.MainPage"
  <Grid x:Name="LayoutRoot" Background="Gray" Height="200" Width="300">
      <RowDefinition Height="*" />
      <RowDefinition Height="2*" />
    <TextBox x:Name="txtResult" Height="40" Text="" Margin="12,14,22,14" />
    <StackPanel Orientation="Horizontal" Grid.Row="1" >
        <TextBox x:Name="txtNumber1" Height="40" Width="99"  Canvas.Left="20" Canvas.Top="30"/>
        <Button x:Name="btnAdd" Height="40" Width="50" Content="+" Canvas.Left="120" Canvas.Top="30" />
        <TextBox x:Name="txtNumber2" Height="40" Width="99"  Canvas.Left="170" Canvas.Top="30"/>


1. Divided the main grid in two rows.

2. In first row put a textbox to display the result.

3. In second row put a stack panel with horizontal orientation.

4. Put a canvas inside stack panel

5. Put two text box and button in canvas.

3. Right click on SilverLight project and add Service Reference.


Give the URL of the WCF service hosted in IIS in Address text box. And then click GO.


4. Calling the Service

Add namespace


On click event of the button



1. Silverlight calls WCF service asynchronously

2. So first completed event is getting called. If operation contract name is GetMessage then event name will be GetMessageCompleted.

3. After event aysnc function is being called.


using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Shapes;
using SilverlightApplication3.ServiceReference1;

namespace SilverlightApplication3
    public partial class MainPage : UserControl
        public MainPage()
            btnAdd.Click += new RoutedEventHandler(btnAdd_Click);

        void btnAdd_Click(object sender, RoutedEventArgs e)

            Service1Client proxy = new Service1Client();
            proxy.GetMessageCompleted += delegate(object sender1, GetMessageCompletedEventArgs e1) { txtResult.Text = e1.Result;};
            proxy.GetMessageAsync(txtNumber1.Text ,txtNumber2.Text);






In this article we saw how we can consume WCF Service in Silverlight application with cross domain. I hope this article was useful. Thanks for reading. Happy Coding

One response to “WCF 4.0 service consumed in Silverlight 4.0 avoiding cross domain problem”

  1. Excellent tutorial, a MUST read for any SL developer!

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