Client side pseudo post back - time...

Does anyone know how to get a client to post back to a server automatically? This is the situation...

Client requests a page - I record the time the request is made, send the page and record the time it is sent - I then need the client to confirm that it has received the request so that I can record that time. That is the entire transaction.

I do not want to open a popup/popunder but I suppose frames could solve that... i.e. would I be best serving the *first* page for the user, opening a frame with the "onload" event, then serving the *second* frame with javascript to display the content of the *first* page? (The first page *should* be hidden until I've recorded the arrival time.

I know... I know... this is cyclic and could go on forever, but I need to record times...

Any other ideas are greatly appreciated.

Cheers