asynchronous processing?

I want to POST data to a server and get back an immediate response. Independently, I want the action to cause the server to submit its own POST request to another server. I do not want the original POST to block while waiting for the second POST to complete. I recently read an article [1] that said that register_shutdown_function was not capable of doing this (it causes the original request to block) and that a new function called apache_register_shutdown_function would allow this. Unfortunately, I don't see my host upgrading to 4.3.1 anytime soon (assuming that the function is even in that version). So are there any alternative methods? --- Seairth Jacobs seairth@seairth.com [1] http://www.php.net/manual/en/function.register-shutdown-function.php