how to make my php page wait for a post(xml string)?

[spaxi]

I have a Login class that will parse an xml sent from an iOS, Android phone. I'm not very good at php and my question is, how do I make my php page wait for a post? or do I just use \[code\]$xml = $_POST['login.xml']; .... //parse ....echo $responsexml;\[/code\]he also suggested \[code\]$xml=readfile("php://input");\[/code\]to read the xml string. I'm much confused about this post business. Any help will be greatly apreaciated!