Trap pre-Postback event to save values in session object.

Hi,

I have a number of values (including datasest) that I need to store in the session object.  One of these is real-time data that is constantly being streamed to my app.  

Is there a way of writing a generic trap-all-postbacks so that I can then update my session object BEFORE the actual post back.  ie If the user does ANYTHING that will cause a postback I want to have already updated my Session with all the required values so that I can repopulate them in the Page_load event.

Thanks.

James.