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Notification - Session Timeout Notification

Your Session will expire in 2 minutes
Notification will be shown in:
60 seconds
Isolate this demo as a stand-alone application

A common scenario is to show a notification to inform the user that their session is about to expire and to let them continue it if they want. Implementing this will require a timer and a mechanism (at best - a callback, AJAX and postback will also do the trick) to contact the server to restart the session if the user decides this. All this is very simple to achieve with RadNotification as shown in the demo. The demo achieves this scenario almost codeless, the additional code is for UI labels and demonstration purposes.

Here is how to easily achieve the core functionality step-by-step:

  1. The ShowInterval property is set to automatically show the popup as time before session timeouts as you desire. This simple setting replaces using any timers at all.
  2. The Value property is set to the desired url of the page which shows when session expires. You could, of course, evaluate it on the client or send it through different techniques, even hardcode it, but this way is more elegant and the notification takes care of sending it to the client where you can easily extract it.
  3. Declare a handler for the OnCallbackUpdate event (it could be simply blank) and call the client-side update() method when you want to restart the session. This will automatically perform a callback to the server that will renew the user session. This is a codeless performance boost.
  4. If the session should not be restarted, simply use the client-side get_value() method to extract the URL and redirect to it.

Following these steps will let you avoid using the lenghty JavaScript used to create the beautiful timers in this demo.

As a conclusion, RadNotification is a very good, almost codeless solution for this popular scenario. The same can be achieved with other popups as well, but this approach is the most straightforward one.

Important notes on using the example: this is a counter for the server Session, not client-side inactivity. If you want to reset the notification timer upon certain actions, look into the following options:

  • Placing the RadNotification in an UpdatePanel with UpdateMode=Always will dispose it with every postback (full or partial), so any other user action that leads to a postback will reset the timer.
  • You may want to register a script from the code-behind that will reset all other UI timers. In this demo the resetTimer function is used for this task.
  • If you want to reset the RadNotification timer upon client-side events, you can do this with the following JavaScript:
    var showIntervalStorage = notification.get_showInterval();
<%@ Page Language="C#" AutoEventWireup="true" CodeFile="DefaultCS.aspx.cs" Inherits="Telerik.Web.Examples.Notification.SessionTimeout.DefaultCS" %>

<%@ Register TagPrefix="telerik" Namespace="Telerik.Web.UI" Assembly="Telerik.Web.UI" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.1//EN" "http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd">
<html xmlns='http://www.w3.org/1999/xhtml'>
<head runat="server">
    <title>Telerik ASP.NET Example</title>
    <link href="styles.css" rel="stylesheet" type="text/css" />
    <form id="form1" runat="server">
    <telerik:RadScriptManager runat="server" ID="RadScriptManager1" />
    <telerik:RadSkinManager ID="RadSkinManager1" runat="server" ShowChooser="true" />
    <script type="text/javascript">
        //----------------------- code related only to the demo UI --------------------------------------//

        //all the timers declared below are used for the demo UI only - to update UI texts. 
        //The functionality related to the scenario itself is handled by RadNotification automatically out of the box
        var mainLblCounter = null;
        var timeLeftCounter = null;
        var seconds = 60;
        var secondsBeforeShow = 60;
        var mainLabel;

        //start the main label counter when the page loads
        function pageLoad() {
            var xmlPanel = $find("<%= RadNotification1.ClientID %>")._xmlPanel;
            mainLabel = $get("mainLbl"); resetTimer("mainLblCounter", updateMainLabel, 1000);

        //stop timers for UI 
        function stopTimer(timer) {
            this[timer] = null;

        //reset timers for UI
        function resetTimer(timer, func, interval) {
            this[timer] = setInterval(Function.createDelegate(this, func), interval);

        function OnClientShowing(sender, args) {
            //deal with UI labels
            mainLabel.innerHTML = 0;
            resetTimer("timeLeftCounter", UpdateTimeLabel, 1000);

        function updateMainLabel(toReset) {
            secondsBeforeShow = (toReset == true) ? 60 : secondsBeforeShow - 1;
            mainLabel.innerHTML = secondsBeforeShow;

        function OnClientHidden() {
            mainLabel.style.display = "";
            resetTimer("mainLblCounter", updateMainLabel, 1000);

        //-----------------------end of code related only to the demo UI --------------------------------------//

        //update the text in the label in RadNotification
        //this could also be done automatically by using UpdateInterval. However, this will cause callbacks [which is the second best solution than javascript] on every second that is being count
        function UpdateTimeLabel(toReset) {
            var sessionExpired = (seconds == 0);
            if (sessionExpired) {
                //redirect to session expired page - simply take the url which RadNotification sent from the server to the client as value
                window.location.href = $find("<%= RadNotification1.ClientID %>").get_value();
            else {
                var timeLbl = $get("timeLbl");
                timeLbl.innerHTML = seconds--;

        function ContinueSession() {
            var notification = $find("<%= RadNotification1.ClientID %>");
            //we need to contact the server to restart the Session - the fastest way is via callback
            //calling update() automatically performs the callback, no need for any additional code or control

            //resets the showInterval for the scenario where the Notification is not disposed (e.g. an AJAX request is made)
            //You need to inject a call to the ContinueSession() function from the code behind in such a request
            var showIntervalStorage = notification.get_showInterval(); //store the original value
            notification.set_showInterval(0); //change the timer to avoid untimely showing, 0 disables automatic showing
            notification.set_showInterval(showIntervalStorage); //sets back the original interval which will start counting from its full value again

            seconds = 60;
    <div class="demo-container no-bg">
    <div class="clockSession">
        <div class="contSession">
            <div class="sesseionExpire">
                Your Session will expire in
                <%= Session.Timeout %>
            <div class="showNotification">
                Notification will be shown in:</div>
            <div class="timeRemain">
                <span class="timeSeconds"><span id="mainLbl">60 </span></span>seconds</div>
    <telerik:RadNotification ID="RadNotification1" runat="server" Position="Center" Width="240"
        Height="100" OnCallbackUpdate="OnCallbackUpdate" OnClientShowing="OnClientShowing"
        OnClientHidden="OnClientHidden" LoadContentOn="PageLoad" AutoCloseDelay="60000"
        Title="Continue Your Session" TitleIcon="" Skin="Office2007" EnableRoundedCorners="true"
        ShowCloseButton="false" KeepOnMouseOver="false">
            <div class="infoIcon">
                <img src="images/infoIcon.jpg" alt="info icon" /></div>
            <div class="notificationContent">
                Time remaining:&nbsp; <span id="timeLbl">60</span>
                <telerik:RadButton Skin="Office2007" ID="continueSession" runat="server" Text="Continue Your Session"
                    Style="margin-top: 10px;" AutoPostBack="false" OnClientClicked="ContinueSession">

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