var variables:URLVariables = new URLVariables();
variables.miavariabile = "Ciao";
var request:URLRequest = new URLRequest();
request.url = "http://www.miodominio.com/miapagina.php";
request.method = URLRequestMethod.POST;
request.data = variables;
var loader:URLLoader = new URLLoader();
loader.dataFormat = URLLoaderDataFormat.TEXT;
loader.addEventListener(Event.COMPLETE, completeHandler);
try {
	loader.load(request);
} catch (error:Error) {
	trace("Errore nel caricamento dell' URL");
}
function completeHandler(event:Event):void {
	var x_xml:XML = XML(event.target.data);
	trace(x_xml);
}

http://www.undolog.com/2007/12/14/flash-cs3-comunicazione-con-un-web-server/

Flash CS3: comunicazione con un Web Server

php, actionscript, post, server, flash, xml, web

ActionScript 3