Question

I’m attempting to use jQuery Ajax call with Json to call a webservice which is a pass-through and calls another webservice. This works if I don’t use ajax, works as an ajax call to the backend service directly, but does not work as ajax call to pass-through service. My question is how do I get an ajax to pass-through webservice to webservice to work?

This is the code I have so far:

[ServiceContract]
public interface IService1
{

    [OperationContract]
    [WebInvoke(Method = "POST", BodyStyle = WebMessageBodyStyle.WrappedRequest, ResponseFormat = WebMessageFormat.Json, RequestFormat = WebMessageFormat.Json)]
    string GetData(int value);
    }

Behind webservice:

[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class Service1 : IService1
{
    public string GetData(int value)
    {
        return string.Format("You entered: {0}", value);
    }
}

Pass-through service:

[AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
public class Service2 : IService1
{
    public string GetData(int value)
    {
       var service = new ServiceReference1.Service1Client("clientContractStuff");
       var testString = service.GetData(value);
       return testString;
    }
}

Page code behind:

public partial class WebUserControl1 : System.Web.UI.UserControl
{
    protected void CodeBehindWcf(object sender, EventArgs e)
    {
        var service = new ServiceReference1.Service1Client("clientContractStuff");
        var testString = service.GetData(5);
        TextBox1.Text = testString;
    }

    protected void CodeBehindWcfUsingService2(object sender, EventArgs e)
    {
        var service = new Service2();
        var testString = service.GetData(5);
        TextBox2.Text = testString;
    }
}

Javascript and Html:

<%@ Control Language="C#" AutoEventWireup="true" CodeBehind="WebUserControl1.ascx.cs"
    Inherits="WcfService1.WebUserControl1" %>
<script type="text/javascript" src="Scripts/jquery-1.4.4-vsdoc.js"></script>
<script type="text/javascript" src="Scripts/jquery-1.4.4.min.js"></script>
<script type="text/javascript">
    function ajaxService2() {
        serviceUrl = "Service2.svc/GetData";
        $.ajax({
            type: "POST",
            url: serviceUrl,
            data: "{\"value\":\"1\"}",
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: function (transport) {
                var string = transport;
                $("#Text2").val(string);
            }
        });
    }

    function ajaxService1() {
        serviceUrl = "Service1.svc/GetData";
        $.ajax({
            type: "POST",
            url: serviceUrl,
            data: "{\"value\":\"2\"}",
            contentType: "application/json; charset=utf-8",
            dataType: "json",
            success: function (transport) {
                var string = transport;
                $("#Text1").val(string);
            }
        });
    }
</script>
<p>
    <input id="Button1" type="button" value="Ajax call service 1" onclick="ajaxService1()" />
    <input id="Text1" name="Text1" type="text" /></p>
<p>
    <input id="Button2" type="button" value="Ajax call service 2" onclick="ajaxService2()" />
    <input id="Text2" name="Text2" type="text" /></p>
<p>
    <asp:Button ID="Button3" runat="server" Text="Code Behind" OnClick="CodeBehindWcf" />
    <asp:TextBox ID="TextBox1" runat="server"></asp:TextBox></p>
<p>
    <asp:Button ID="Button4" runat="server" Text="Code Behind Use Service 2" OnClick="CodeBehindWcfUsingService2" />
    <asp:TextBox ID="TextBox2" runat="server"></asp:TextBox></p>

Everything works except Button 2 and ajaxService2 function. This throws an error: ‘The remote server returned an unexpected response: (400) Bad Request.’

Answer 1

In order to use Ajax, webhttpbinding must be used for the endpoint of the pass-through webservice and I assumed would also be used for the backend service.

Looking at the autogenerated service reference code in ‘Service References\Reference.cs’:

public interface IService1 {

    [System.ServiceModel.OperationContractAttribute(Action="http://tempuri.org/IService1/GetData", ReplyAction="http://tempuri.org/IService1/GetDataResponse")]
    string GetData(int value);
}

It’s easy to see it’s generating code under SOAP and not REST. Since webhttpbinding is a REST binding it will not work. I changed the backend service to use basichttpbinding and everything works as it should.