AS3 PHP small question

I can talk to PHP from AS3. Question though. Do I need to set up a listener in flash/as3 or something, for this kind of a scenario?

Let’s say I goto this webpage (currently my localhost, and it works)
http://localhost/hello.php?my_id=555

That number “555” is arbitrary, and could be any number. If I want to type in 555, or 345, or any number, how would I have it talk to my AS3?

The way I have it is, I published my FLA as an HTML and SWF file. I then just took the HTML file, and made it a PHP file. I have this PHP on the top:

<?php
$my_id = $_REQUEST['my_id']

I can echo it no problem.

echo "this is " . $my_id;
?>

Again, how would I have this then talk to my AS3? Do I need a timer or a listener to constantly listen to see if that number changes? tyty