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<%@ Page Language="C#" AutoEventWireup="true" CodeFile="Default.aspx.cs" Inherits="RandomNumber" %>
<!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 id="Head1" runat="server">
<title>Callback Page</title>
<script type="text/javascript">
function GetNumber(){
UseCallback();
}
function GetRandomNumberFromServer(TextBox1, context){
document.forms[0].TextBox1.value = TextBox1;
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<input id="Button1"
type="button"
value="Get Random Number"
onclick="GetNumber()" />
<br />
<br />
<asp:TextBox ID="TextBox1" Runat="server"></asp:TextBox>
</div>
</form>
</body>
</html>
File: Default.aspx.cs
using System;
using System.Data;
using System.Configuration;
using System.Collections;
using System.Web;
using System.Web.Security;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;
public partial class RandomNumber : System.Web.UI.Page, System.Web.UI.ICallbackEventHandler
{
private string _callbackResult = null;
protected void Page_Load(object sender, EventArgs e)
{
string cbReference = Page.ClientScript.GetCallbackEventReference(this,
"arg", "GetRandomNumberFromServer", "context");
string cbScript = "function UseCallback(arg, context)" +
"{" + cbReference + ";" + "}";
Page.ClientScript.RegisterClientScriptBlock(this.GetType(),
"UseCallback", cbScript, true);
}
public void RaiseCallbackEvent(string eventArg)
{
Random rnd = new Random();
_callbackResult = rnd.Next().ToString();
}
public string GetCallbackResult()
{
return _callbackResult;
}
}
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