I need to be notified any time a largeish asp.net mvc web application makes an ajax call to the server. We're using both jquery, and the built-in Ajax.* methods to do the remote calls, and I would like a global way of knowing when we make a call without having to manually inject some sort of "IsMakingCall" method to every request.

The root problem we're trying to solve is session timeout. If the user leaves a page up and goes to lunch (for example), they get errors when they get back because the ajax call is returning the login page instead of the expected json or partial html result.

My idea was to have a js timer which would be reset any time we make an ajax call. That way, if the timer runs out (ie. their session has now timed out) I can just auto-log them out. This is how sites like bank of america and mint.com work.

Thanks!