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Vijay Kodali
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Alert user before session timeout

Here is a quick & dirty trick to alert users on session timeout. This is not a perfect solution. But it will give reader an idea to work on...

Some facts before we start:

Session doesn't end

  • When the user closes his browser
  • When the user navigates away from your page
  • When user connection lost.

Session ends, when the server hasn't gotten a request from the user in a specific time (Session timeout value).

In this solution, I am using ajaxtoolkit’s modalpopupextender control to alert user about expiring session.

Each time a page is rendered back to the client, I am injecting JavaScript that will show modalpopup two minutes before session timeout. I am passing the session expiry value to the client side java script. This will execute a countdown, and at the end display the Popup.

I added modalpopupextender to the page and set its target control id to a panel. That panel contains alert message and two buttons.


The Page_Load code looks like this.


I added two java script functions, one for showing alert message and second one is for hiding that message.

Here are javascript functions


That’s it. Run the application and it will check 2 minutes before the timeout and provide user the option to "slide" the session. If user clicks “OK” it will refresh page, which in turn will slide the session. If user clicks “Cancel” the popup will hide.



You can improve this code on each step. Like for example, to renew session you don’t have to refresh the page. You can just call web service from client side etc.

If you have any questions, leave a comment.

Posted by Vijay on Thursday, May 20, 2010 8:51 PM
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Asp.net session on browser close

How to capture logoff time when user closes browser?


How to end user session when browser closed?

These are some of the frequently asked questions in asp.net forums.

In this post I'll show you how to do this when you're building an ASP.NET web application.

Before we start, one fact:

There is no full-proof technique to catch the browser close event for 100% of time. The trouble lies in the stateless nature of HTTP. The Web server is out of the picture as soon as it finishes sending the page content to the client. After that, all you can rely on is a client side script. Unfortunately, there is no reliable client side event for browser close.


The first thing you need to do is create the web service. I've added web service and named it AsynchronousSave.asmx. 

 Open Dialog

Make this web service accessible from Script, by setting class qualified with the ScriptServiceAttribute attribute... 


Add a method (SaveLogOffTime) marked with [WebMethod] attribute. This method simply accepts UserId as a string variable and writes that value and logoff time to text file. But you can pass as many variables as required. You can then use this information for many purposes.


To end user session, you can just call Session.Abandon() in the above web method.

To enable web service to be called from page’s client side code, add script manager to page. Here i am adding to SessionTest.aspx page


When the user closes the browser, onbeforeunload event fires on the client side. Our final step is adding a java script function to that event, which makes web service calls. The code is simple but effective


My Code

HTML:( SessionTest.aspx )


C#:( SessionTest.aspx.cs )


That’s’ it. Run the application and after browser close, open the text file to see the log off time.


The above code works well in IE 7/8. If you have any questions, leave a comment.

Posted by vijay on Thursday, April 29, 2010 6:09 PM
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