Notify user about session timeout in Java EE

Question

My requirement is to notify the user with a popup saying that the user session is about to time out in x seconds in case user does not perform any activity on the web page.<

Answer 1

Either it may be simple servlet, spring-mvc or spring-security auto logout is not possible without perfect client side logic.
Considering application will have both type of request

• AJAX and
  
• form submission/page reload
  

Auto logout needs very calculated logic. Presenting my autologout functionality implementation with following

Advantages.

---

1. No extra call/request is used to achieve this. considering performance impact if more than 10k active users and extra calls to achieve auto logout.
2. One line configuration using tag.
3. Works flawlessly even if user opens multiple tab or multiple window.
4. It intimates you before 30 seconds of session invalidation, so if you have filled form and not submitted, you can keep session alive(extend session by one click). So user less likely to loose unsaved data.

Usage

---

1. Include auto logout script in required JSP pages as given below.

    ....
    </body>
    <jsp:include page="../template/autologout-script.jsp"></jsp:include>
</html>

2. Create a JSP page, autologout-script.jsp and add below code. Note: No editing/configuring is required

<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>

<script>
$(document).ready(function()
{
    var timeOutTimeInSeconds = ${ timeOutTimeInSeconds }; 
    var showTimerTimeInSeconds= ${ showTimerTimeInSeconds };

    var sessionCheckIntervalId = setInterval(redirectToLoginPage, timeOutTimeInSeconds * 1000);
    var timerDisplayIntervalId = setInterval(showTimer, (timeOutTimeInSeconds - showTimerTimeInSeconds) * 1000);
    var badgeTimerId;
    window.localStorage.setItem("AjaxRequestFired", new Date());

    function redirectToLoginPage(){
        //location.href =  '<c:url value="/" />'+'${loginPageUrl}';
        window.location.reload();
    }

    $(document).ajaxComplete(function () {
        resetTimer();
    });

    $(window).bind('storage', function (e) {
         if(e.originalEvent.key == "AjaxRequestFired"){
             console.log("Request sent from another tab, hence resetting timer")
             resetTimer();
         }
    });

    function resetTimer()
    {
        showTimerTimeInSeconds= ${ showTimerTimeInSeconds };

        console.log("timeOutTimeInSeconds : "+timeOutTimeInSeconds)
        window.localStorage.setItem("AjaxRequestFired", new Date());

        window.clearInterval(sessionCheckIntervalId);
        sessionCheckIntervalId = setInterval(redirectToLoginPage, timeOutTimeInSeconds * 1000);

        window.clearInterval(timerDisplayIntervalId);
        timerDisplayIntervalId = setInterval(showTimer, (timeOutTimeInSeconds - showTimerTimeInSeconds) * 1000);

        hideTimer();
    }

    function showTimer()
    {
        $('#sessionTimeRemaining').show();
        $('#sessionTimeRemainingBadge').html(showTimerTimeInSeconds--);
        window.clearInterval(timerDisplayIntervalId);
        badgeTimerId = setInterval(function(){
            $('#sessionTimeRemainingBadge').html(showTimerTimeInSeconds--);
        }, 1000);
    }

    function hideTimer()
    {
        window.clearInterval(badgeTimerId);
        $('#sessionTimeRemaining').hide();
    }
});
</script>

3. Configure session attributes to configuring timeout setting Note: Configure this after session creation. You can implement HttpSessionListener sessionCreated method and set the following configuration as per your requirement.

session.setMaxInactiveInterval(300);

session.setAttribute("timeOutTimeInSeconds", 300);
session.setAttribute("showTimerTimeInSeconds", 30);

4. Add below html for displaying timer.
Note: it can be moved to autologout-script template page if you are good at CSS. Hence you can avoid to add this in each and every page.
Include bootstrap or add your custom css.

<span class="badge badge-primary" title="click to keep session alive" id="sessionTimeRemaining" 
    onclick="ajaxSessionRefresh()" style="display:none;">
    <i class="badge badge-danger" id="sessionTimeRemainingBadge" style="float:left">30</i>
     &nbsp; 
     <small>Refresh</small>
     <i class="glyphicon glyphicon-refresh"></i>
</span>

That is all about a simple auto logout implementation. You can download working example from my github repository
Autologout using simple servlet example
Autologout using spring-security java configuration example
Autologout using spring-security xml configuration example

Logic Explained

---

Case 1: On Page load
Here logic is simple, on page load set timer of interval equlas to maxInactiveInterval. after timeout redirect to login page.
Case 2: Keep track AJAX calls
Now considering AJAX requests, you can use .ajaxStart() or .ajaxComplete() callbacks of jquery so that if any ajax request is fired you can reset the interval.
Case 3: Tracking multi tab/window activity
Intertab communication is done to synchronize state of each tab. Used localStorage on change event.

Limitations/Improvements required
1. If maximum allowed session is one, if session is taken from another system, AJAX request will fail. It needs to be handled to redirect to login page.
2. Use ajaxStart() instead of ajaxComplete() to have exact sync of idleTime values between server and browser.

Requirements
1. Jquery

Alternatives to current implementation compared

---

1. Setting Refresh header in http response. (Not works for AJAX requests)

response.setHeader("Refresh", "60; URL=login.jsp");

2. Setting meta refresh tag in HTML (Not works for AJAX requests)

<meta http-equiv="refresh" content="60; url=login.jsp">

3. Configuring Activity checker Keeps session alive by repeated AJAX request. Tracks idle time and makes logout request after timeout.
   No doubt it is a good one with simple logic. But i want to just ink my observations.
   • Performance impact if 2 requests are made per minute to keep session alive and 50k active users. 100k requests per minute.
   • Intertab communication If two tabs are open, one tab is receiving activity but other tab is not receiving activity, that tab fires logout request and invalidate session even though activity is present in other tab. (But can be handled)
   • Force logout approach It is a client is dominated over server to invalidate session.

Answer 2

Make use of HttpSession#getMaxInactiveInterval() and setTimeout(). There's no need for Ajax in this particular purpose, unless you want to postpone the timeout on every client activity (polling).

Basic example:

<script>
    var secondsBeforeExpire = ${pageContext.session.maxInactiveInterval};
    var timeToDecide = 15; // Give client 15 seconds to choose.
    setTimeout(function() {
        alert('Your session is about to timeout in ' + timeToDecide + ' seconds!')
    }, (secondsBeforeExpire - timeToDecide) * 1000);
</script>

To decrement the time inside the message magically, then instead of the basic alert() you'll need an overlay with a div wherein you have control over the content through HTML DOM tree and make use of another setTimeout() on 1 second to change the text dynamically.

Note that this script has to be served by the JspServlet to get the EL to work. Thus, you need to put the script in the HTML <head> of the JSP page, or if you really want to have all the JS in a separate *.js file, then you need to let the JspServlet handle any *.js requests as well.

Answer 3

I don't think that Java/Java EE will be really helpful here as this need to be handled on the client-side (i.e. using JavaScript). One solution I can think of would be to set a kind of timer that would notify the user a few minutes before the server's timeout.

While googling about this, I found Eric Pascarello's Update User's Session with AJAX blog post (and the reloaded version Updating User Session with Ajax - Round 2) that precisely describes such a solution (and use an XMLHttpRequest to update the session). His Ajax Session Management script is available here.