Using Web Service From Client- Side Code

Ahmed Salah
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Before you begin with the client-side code, you should have a server code that will respond to all the requests coming from your client-server code. In this case, I've created a web service to handle the requests. Notice the green comments.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.Script.Serialization;
using System.Web.Script.Services;
using System.Web.Services;
using System.Xml.Linq;
namespace DataReaderService
{
/// <summary>
/// Summary description for EmpReader
/// </summary>
[WebService]
//[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 EmpReader : System.Web.Services.WebService
{
[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json) ] //format the returned string value as JSON string
public string getEmpData(string id)
{
//Create a list of 'employee' object
List<employee> emps = new List<employee>();
//Load the XML document
var employee = XElement.Load( Server.MapPath("Employees.xml") );
//Select the employee with given ID
var emp = from q in employee.Elements("Employee")
where q.Element("EmpId").Value == id
select q;
//Return a message to the client if no data returned
if (emp.Count()==0) { return "no data"; }
//Iterate through emp collection to populate a list of 'employee'
foreach (var element in emp)
{
//Gets Phone elements
var e = from j in element.Elements("Phone")
select j;
object[] phones = e.ToArray(); //Convert phone to array in order to be able to read their values only
emps.Add(new employee { Name = element.Element("Name").Value, gender = element.Element("Sex").Value, Address = element.Element("Address").Value, HomePhone = ((XElement)phones[0]).Value , WorkPhone=((XElement)phones[1]).Value });
}
//return emps;
return new JavaScriptSerializer().Serialize(emps); //use this to return as JSON object
}
}
public class employee
{
public string Name { get; set; }
public string gender { get; set; }
public string HomePhone { get; set; }
public string WorkPhone { get; set; }
public string Address { get; set; }
}
}

You may change how the server handles the requests to add more functionality. Now it's time to write our client-side code, and here are some different ways:

Classic JavaScript

var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function () {
if (xhttp.readyState == 4 && xhttp.status == 200) {
var server_data = xhttp.responseXML;
//When using xhttp.responseXML, data can be returned in XML format , we get 'string' TAG contents
var XMLData = server_data.getElementsByTagName("string")[0].childNodes[0].nodeValue;
// //Check if data found
if (XMLData != "no data") {
$("#txtResult").val(XMLData);
//parse JSON data
var Result = JSON.parse(XMLData);
//Draw Header
$("#table_results").append("<tr><th>Name</th><th>Gender</th><th>Address</th><th>Home Phone</th><th>Work Phone</th></tr>");
//Display data
$("#txtResult").val(Result[0].Name);
$("#table_results").append("<tr><td>" + Result[0].Name + "</td><td>" + Result[0].gender + "</td><td>" + Result[0].Address + "</td><td>" + Result[0].HomePhone + "</td><td>" + Result[0].WorkPhone + "</td></tr>");
} else { $("#txtResult").val("No Data found"); }
}
};
xhttp.open("POST", "http://localhost:56998/EmpReader.asmx/getEmpData", true);
xhttp.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
xhttp.send("id=" + $("#txtEmpId").val() );

Using $.post method

$.post("http://localhost:56998/EmpReader.asmx/getEmpData",
{ id: $("#txtEmpId").val() },
function (data) {
//Get data received from the server in XML format
var data_packet = data.getElementsByTagName("string")[0].childNodes[0].nodeValue;
//if invalid number sent, type an error message
if (data_packet == "no data") $("#txtResult").val("No Data Found");
else //if data found , draw the table
{
//parse JSON data
var json_data = JSON.parse(data_packet);
$("#txtResult").val(json_data[0].Name);
//Draw the table
//1. Draw the header
$("#table_results").append("<tr><th>Name</th><th>Gender</th><th>Address</th><th>Home Phone</th><th>Work Phone</th></tr>");
//Draw table body and write data
$("#table_results").append("<tr><td>" + json_data[0].Name + "</td><td>" + json_data[0].gender + "</td><td>" + json_data[0].Address + "</td><td>" + json_data[0].HomePhone + "</td><td>" + json_data[0].WorkPhone + "</td></tr>");
}
});

Using $.ajax method

$.ajax({
type: "POST",
contentType: "application/json; charset=utf-8",
url: "http://localhost:56998/EmpReader.asmx/getEmpData",
data: '{id:"' + $("#txtEmpId").val() + '"}',
dataType: "json",
success: function (data) {
//Check if there is data returned from the server
if (data.d != "no data") {
//return all data from the server
var Result = JSON.parse(data.d);
//Draw Header
$("#table_results").append("<tr><th>Name</th><th>Gender</th><th>Address</th><th>Home Phone</th><th>Work Phone</th></tr>");
$("#txtResult").val(Result[0].Name);
$("#table_results").append("<tr><td>" + Result[0].Name + "</td><td>" + Result[0].gender + "</td><td>" + Result[0].Address + "</td><td>" + Result[0].HomePhone + "</td><td>" + Result[0].WorkPhone + "</td></tr>");
} else { $("#txtResult").val("No data found"); } //return error message
},
error: function (result) {
alert("Error reading data");
}
});