How to: Create an AJAX-Enabled WCF Service and an ASP.NET Client that Accesses the Service

Article
09/15/2021

This topic shows how to use Visual Studio to create an AJAX-enabled Windows Communication Foundation (WCF) service and an ASP.NET client that accesses the service.

Create an ASP.NET web app

Open Visual Studio.
From the File menu, select New > Project
In the New Project dialog, expand the Installed > Visual C# > Web category, and then select ASP.NET Web Application (.NET Framework).
Name the Project SandwichServices and click OK.
In the New ASP.NET Web Application dialog, select Empty and then select OK.

Add a web form

Right-click the SandwichServices project in Solution Explorer and select Add > New Item.
In the Add New Item dialog, expand the Installed > Visual C# > Web category, and then select the Web Form template.
Accept the default name (WebForm1), and then select Add.

WebForm1.aspx opens in Source view.

Add the following markup inside the <body> tags:

<input type="button" value="Price of 3 sandwiches" onclick="Calculate()"/>
<br />
<span id="additionResult"></span>

Create an AJAX-enabled WCF service

Right-click the SandwichServices project in Solution Explorer and select Add > New Item.
In the Add New Item dialog, expand the Installed > Visual C# > Web category, and then select the WCF Service (AJAX-enabled) template.
Name the service CostService and then select Add.

CostService.svc.cs opens in the editor.
Implement the operation in the service. Add the following method to the CostService class to calculate the cost of a quantity of sandwiches:
```
[OperationContract]
public double CostOfSandwiches(int quantity)
{
    return 1.25 * quantity;
}
```

Configure the client to access the service

Open the WebForm1.aspx file and select the Design view.
From the View menu, select Toolbox.
Expand the AJAX Extensions node and drag and drop a ScriptManager onto the form.
Back in the Source view, add the following code between the <ScriptManager> tags to specify the path to the WCF service:
```
<Services>
   <asp:ServiceReference Path="~/CostService.svc" />
</Services>
```
Add the code for the JavaScript function Calculate(). Place the following code in the head section of the web form:
```
<script type="text/javascript">

    function Calculate() {
        CostService.CostOfSandwiches(3, onSuccess);
    }

    function onSuccess(result) {
        var myres = $get("additionResult");
        myres.innerHTML = result;
    }

</script>
```
This code calls the method of CostService to calculate the price for three sandwiches, and then displays the result in the span called additionResult.

Run the program

Make sure that WebForm1.aspx has focus, and then press Start button to launch the web client. The button has a green triangle and says something like IIS Express (Microsoft Edge). Or, you can press F5. Click the Price of 3 sandwiches button to generate the expected output of "3.75".

Example

The following is the full code in the CostService.svc.cs file:

using System.ServiceModel;
using System.ServiceModel.Activation;

namespace SandwichServices
{
    [ServiceContract(Namespace = "")]
    [AspNetCompatibilityRequirements(RequirementsMode = AspNetCompatibilityRequirementsMode.Allowed)]
    public class CostService
    {
        [OperationContract]
        public double CostOfSandwiches(int quantity)
        {
            return 1.25 * quantity;
        }
    }
}

The following is the full contents of the WebForm1.aspx page:

<%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="SandwichServices.WebForm1" %>

<!DOCTYPE html>

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
    <script type="text/javascript">

        function Calculate() {
            CostService.CostOfSandwiches(3, onSuccess);
        }

        function onSuccess(result) {
            var myres = $get("additionResult");
            myres.innerHTML = result;
        }

    </script>
</head>
<body>
    <form id="form1" runat="server">
        <div>
        </div>
        <asp:ScriptManager ID="ScriptManager1" runat="server">
            <Services>
                <asp:ServiceReference Path="~/CostService.svc" />
            </Services>
        </asp:ScriptManager>

        <input type="button" value="Price of 3 sandwiches" onclick="Calculate()" />
        <br />
        <span id="additionResult"></span>
    </form>
</body>
</html>