var req;
function HttpRequest(url,method,async,params) {
	req=false;
	// codice per Mozilla, etc.
	if (window.XMLHttpRequest) {
		try {
			req=new XMLHttpRequest();
		} catch(e) {
			alert(e);
		}
	}
	// codice per  IExplore
	else if (window.ActiveXObject) {
		try {
			req=new ActiveXObject("Microsoft.XMLHTTP");
		} catch(e) {
			alert(e);
		}
	}
	if (req) {
		try {
			req.onreadystatechange=xmlhttpChange;
			if (method=='POST') {
				req.open(method,url,async);
				req.setRequestHeader("Content-type", "application/x-www-form-urlencoded");
				req.setRequestHeader("Content-length", params.length);
				req.setRequestHeader("Connection", "close");			
				req.send(params);
			} else if (method=='GET') {
				req.open(method,url+"?"+params,async);
				req.send(null);
			}
			return req.responseText;
		} catch (e) {
			alert(e);
		}
	} 
}

function xmlhttpChange() {
	if (req.readyState==4) {
		// if "OK"
		if (req.status==200) {
		} 
	}
}