Introduction:

In this article we will learn to use (consume) a web service in our web application using Ajax (Asynchronous JavaScript and XML). We use Ajax in those applications where we do not want the page to be reloaded for a specific event. Here at first we will create a simple web service with two methods - One for showing message and another for adding two numbers and then we will use this web service into web application using Ajax. So, Let's create a web service. Follow given steps.

Now modify the code of .asmx.cs with the following code.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Services;

namespace wsuingAjax
{
/// <summary>
 /// Summary description for Service1
 /// </summary>
 [WebService(Namespace = "http://tempuri.org/")]
[WebServiceBinding(ConformsTo = WsiProfiles.BasicProfile1_1)]
[System.ComponentModel.ToolboxItem(false)]
// 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 Service1 : System.Web.Services.WebService
 {
[WebMethod(Description="Show Message")]
public string show()
{
return "Hello Web Service!!!";
}
[WebMethod(Description = "Addition of Two Numbers")]
public int add(int a, int b)
{
return a + b;
}
}
}

Now run the application.

Output:

consuming web service using ajax

Now we use this service using Ajax in our web application. Follow the given steps.

  • Go to Visual Studio 2010 and create a New Project.
  • Select a ASP.NET Empty Web Application.
  • Give it a name and click ok button.
  • Right click at your project and add a web form.
  • Right click at your project and select Add Web Reference. Look at below figure.

    consuming web service using ajax
  • After selecting this, a new window will be open like as below figure.

    consuming web service using ajax
  • Copy the URL of your running web service and paste it at the URL (Look in figure) and click "Go" button.

    consuming web service using ajax
  • Click at Add Reference. Now service reference has added in your application.
  • Go to design page of your web application and take ScriptManager at first. Then take UpdatePanel and some other controls and arrange them in given
    order.

    consuming web service using ajax

    Code (WebForm.aspx):

    <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="WebForm1.aspx.cs" Inherits="usingws.WebForm1" %>
    <!    DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

    <    html xmlns="http://www.w3.org/1999/xhtml">
    <    head runat="server">
    <title></title>
     <style type="text/css">
     .style1
     {
    width: 118px;
    }
    .style2
     {
    width: 114px;
    }
    </style>
    </    head>
    <    body>
    <form id="form1" runat="server">
     <div>
    <asp:ScriptManager ID="ScriptManager1" runat="server">
     </asp:ScriptManager>
     <br />
     <asp:UpdatePanel ID="UpdatePanel1" runat="server">
     <ContentTemplate>
     <asp:Button ID="btnshow" runat="server" BackColor="#999966" Height="26px"
    Text="Show " Width="71px" onclick="btnshow_Click" />
    <asp:Button ID="btnadd" runat="server" BackColor="#999966" Text="Add"
    onclick="btnadd_Click" />
     <br /><br />
    <table style="height: 69px; width: 466px">
     <tr>
     <td class="style2">
     <asp:Label ID="lblfn" runat="server" Text="First No."></asp:Label>
     </td>
     <td class="style1">
     <asp:TextBox ID="txtfirst" runat="server"></asp:TextBox>
     </td>
     <td>
     <asp:Label ID="lblshow" runat="server" Text=" "></asp:Label>
     </td>
     </tr>
     <tr>
     <td class="style2">
     <asp:Label ID="lblsn" runat="server" Text="Second No."></asp:Label>
     </td>
     <td class="style1">
     <asp:TextBox ID="txtsecond" runat="server"></asp:TextBox>
     </td>
     <td></td>
     </tr>
     <tr>
     <td class="style2">
     <asp:Label ID="lbladdition" runat="server" Text="Addition"></asp:Label>
     </td>
     <td class="style1">
     <asp:TextBox ID="txtresult" runat="server"></asp:TextBox>
     </td>
     <td></td>
     </tr>
     </table>
    </ContentTemplate>
     </asp:UpdatePanel>
     </div>
     </form>
    </    body>
    </    html>

    Code (WebForm.aspx.cs):

    using System;
    using     System.Collections.Generic;
    using     System.Linq;
    using     System.Web;
    using     System.Web.UI;
    using     System.Web.UI.WebControls;

    namespace     usingws
    {
    public partial class WebForm1 : System.Web.UI.Page
     {
    protected void btnadd_Click(object sender, EventArgs e)
    {
    localhost.Service1 obj = new localhost.Service1();
    txtresult.Text = obj.add(Convert.ToInt32(txtfirst.Text), Convert.ToInt32(txtsecond.Text)).ToString();
    }
    protected void btnshow_Click(object sender, EventArgs e)
    {
    localhost.Service1 obj = new localhost.Service1();
    lblshow.Text = obj.show();
    }
    }
    }

    Run the web application.

    Output:

    consuming web service using ajax

    Click show button to show message (which is specified in web service) and Add button to get addition of two numbers.

    Output:

    consuming web service using ajax