chat comet nginx apache

chat comet nginx apache

I hope the gurus can help me.
file php : www.mysite.com/get_activity.php (use comet)
while(true){
$actibity = get_sql_Activity();
flush();
usleep($1000000);
}
file :/chat_view.php
<iframe src="www.mysite.com/get_activity.php"></iframe>
works fine, but when I open a tab in the browser it is locked until I
close the page that has the iframe
I was thinking to use nginx get_activity and the rest worked in apache
IN nginx (I thought about using a subdomain )
www.mysite.com/get_activity.php -> chat.mysite.com/get_activity.php
<iframe src="chat.mysite.com/get_activity.php" ></iframe>
I wanted the subdomain chat receives requests comet and the rest of the
site worked in apache, can help me with the configuration of nginx? thank
you