ASP.NET AJAX callbacks to Web Methods in ASPX pages ...

In my previous post we have seen basic steps to create AJAX-Enabled WCF Service in web application.
Now in this post, We will see how to implement AJAX web methods.

Why Web Method?? Some times, we need functionality that are logically dedicated to specific ASPX page, in such situation we can use web methods.
How to create:

Step 1: Implementing Web Method

Write WebMethod as below into your code file (.aspx.cs)
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1.[System.Web.Services.WebMethod]
2.    public static List<student> GetStudents(int schoolID)
3.    {
4.        //TODO: Write your logic to get student list
5.    }
6.</student>

Step 2: Add ScriptManager into page

Set EnablePageMethods property of ScriptManager to true as,

1.<asp:scriptmanager id="ScriptManager1" runat="server" enablepagemethods="true">
2.</asp:scriptmanager>

Step 3: Calling WebMethod from javascript

Call the web method through the PageMethods as below,

01.function GetStudents(schoolID) {
02.            PageMethods.GetStudents(schoolID, OnSucceeded, OnFailed);
03.        }
04.
05.        function OnSucceeded(result) {
06.            //TODO: Write logic to display the result from  JSON results to HTML
07.        }
08.
09.        function OnFailed(error) {
10.            // Alert user to the error.
11.            alert(error.get_message());
12.        }

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