ASP.NET MVC - Erasing session data after fer minutes of inactivity - asp.net

Question

In my web application, i often can see, that when i am not doing anything for a few minutes, and then i come back, and refresh the page - i am still being logged in, but my session data is all gone!
On the login() action i am setting up few Session[] objects that are necessary for a page to work correctly. I have no idea why is it doing so, but i need it to log user out whenever it clears his session data.
I have read about setting <sessionState mode="InProc" timeout="20"/> but will this timeout refresh everytime i refresh the page? Or will it run out after 20 minutes from the time i logged in? What if i make this timer bigger than i have on keeping the user online?

Answer 1

Posting back to the server will keep the session alive for longer. It's a sliding expiration. There are two ways to handle from the client, which the client is not aware of this 20 minute timeout:
Create a timer using client javascript that redirects to the logout page when 20 minutes is hit
Whenever a postback happens, check if the session expired (which can be done in a variety of ways, such as checking Session.IsNewSession, see if your objects are lost, etc.) and then redirect to the logout handler before processing the request.

Answer 2

I assume you are using Forms Authentication. Is that correct? If so, you need to have your Forms Authentication ticket's timeout match the Session timeout.
The user stays logged in through a process that is more complicated than it first seems. A cookie is stored in the user's browser that is called the Forms Authentication Ticket. If the user stays idle past the session timeout limit, the server will discard the session. But on the next request, the Forms Authentication Ticket is passed back to the web server. The server validates the ticket, and if it is still valid, the user is logged back in.
As you can see, the user's session is not restored. If you want that behavior, you would have to detect that condition and restore the session yourself.
The solution is to set the Forms Authentication Ticket's timeout to be the same as the Session timeout. You accomplish that in your Web.config file, as explained here:
<system.web>
<authentication mode="Forms">
<forms timeout="20"/>
</authentication>
</system.web>
The timeout value is in minutes. Once the Forms Authentication Ticket's timeout is hit, the user will be logged out. This operates independent from the session's timeout, but if they are the same, they will expire at roughly the same time. If you want to be completely safe, set the Forms Authentication Ticket timeout to be a little shorter than the session timeout. The user will be logged out before their session times out. When they log in again, they will get a new session. The old session will eventually time out on its own.

Answer 3

Try checking this:
Q: In Proc mode, why do I lose all my session occasionally?
A: Please see the "Robustness" section in the "Understanding session
state modes" section of of this article.
Robustness
InProc - Session state will be lost if the worker process
(aspnet_wp.exe) recycles, or if the appdomain restarts. It's because
session state is stored in the memory space of an appdomain. The
restart can be caused by the modification of certain config files such
as web.config and machine.config, or any change in the \bin directory
(such as new DLL after you've recompiled the application using VS) For
details, see KB324772. In v1, there is also a bug that will cause
worker process to restart. It's fixed in SP2 and in v1.1. See
KB321792.
Source - http://forums.asp.net/t/7504.aspx/1