This post discusses how to develop Windows Communication Foundation (WCF) service using AJAX and without any configuration settings for WCF. This service can be consumed from Javascript. The service uses a special setting in .svc file which automatically enables an AJAX endpoint.

You can get the AJAX support for WCF through the ScriptManager control.

1. Create a WCF service project in VS 2010

The service contract code as follows

   1: // Define a service contract.
   2:   [ServiceContract(Namespace = "ConfigFreeWCFAjaxService")]
   3:   public interface ICalculator
   4:   {
   5:       [OperationContract]
   6:       double Add(double n1, double n2);
   7:   }

Service Implementation code as follows

   1: public class CalculatorService : ICalculator
   2: {
   3:     public double Add(double n1, double n2)
   4:     {
   5:         return n1 + n2;
   6:     }
   7: }

The SVC file setting as below

   1: <%@ServiceHost
   2:     language="c#"
   3:     Debug="true"
   4:     Service="ConfigFreeWCFAjaxService.CalculatorService"

   5:     Factory="System.ServiceModel.Activation.

          WebScriptServiceHostFactory"
   6: %>

WebScriptServiceHostFactory automatically add the WebScriptEndpoint to the service.

You need to add the following line in script manager control to call the service from javascript

   1: <asp:ScriptManager ID="ScriptManager" runat="server">
   2:     <Services>
   3:         <asp:ServiceReference Path="service.svc" />
   4:     </Services>
   5: </asp:ScriptManager>

Calling the service from javascript

<script type="text/javascript">

  function makeAJAXCall()

   {

   var n1 = document.getElementById("num1").value;

   var n2 = document.getElementById("num2").value;

   // Instantiate a service proxy

   var proxy = new  ConfigFreeWCFAjaxService.ICalculator();

  // Call correct operation on proxy      
  proxy.Add(parseFloat(n1), parseFloat(n2), onSuccess, onFail, null);           
  break;

  }

</script>

//This function is called when the result from the service call is received

    function onSuccess(mathResult)

     {

        document.getElementById("result").value = mathResult;

    }

The <system.ServiceModel> element can be completely removed from the web.config if you configure your service as shown in the above.