Keeping ASP.NET Session Open / Alive

Do you really need to keep the session (do you have data in it?) or is it enough to fake this by reinstantiating the session when a request comes in? If the first, use the method above. If the second, try something like using the Session_End event handler.

If you have Forms Authentication, then you get something in the Global.asax.cs like

FormsAuthenticationTicket ticket = FormsAuthentication.Decrypt(formsCookie.Value);
if (ticket.Expired)
{
    Request.Cookies.Remove(FormsAuthentication.FormsCookieName);
    FormsAuthentication.SignOut();
    ...             
     }
else
{   ...
    // renew ticket if old
    ticket = FormsAuthentication.RenewTicketIfOld(ticket);
    ...
     }

And you set the ticket lifetime much longer than the session lifetime. If you're not authenticating, or using a different authentication method, there are similar tricks. Microsoft TFS web interface and SharePoint seem to use these - the give away is that if you click a link on a stale page, you get authentication prompts in the popup window, but if you just use a command, it works.