function xhr_sync (url) {
	var req = xhr_createXMLHTTPObject();
	if (!req) return;
	
	req.open("GET", url, false);
	req.send(null);
	return req.responseText;
}

function xhr_async(url, postData, callback) {
	var req = xhr_createXMLHTTPObject();
	if (!req) return;
	var method = (postData) ? "POST" : "GET";
	req.open(method,url,true);
	req.setRequestHeader('User-Agent','XMLHTTP/1.0');
	if (postData)
		req.setRequestHeader('Content-type','application/x-www-form-urlencoded');
	req.onreadystatechange = function () {
		if (req.readyState != 4) return;
		if (req.status != 200 && req.status != 304) {
			//	alert('HTTP error ' + req.status);
			return;
		}
		callback(req);
	}
	if (req.readyState == 4) return;
	req.send(postData);
}

function xhr_XMLHttpFactories() {
	return [
		function () {return new XMLHttpRequest()},
		function () {return new ActiveXObject("Msxml2.XMLHTTP")},
		function () {return new ActiveXObject("Msxml3.XMLHTTP")},
		function () {return new ActiveXObject("Microsoft.XMLHTTP")}
	];
}

function xhr_createXMLHTTPObject() {
	var xmlhttp = false;
	var factories = xhr_XMLHttpFactories();
	for (var i=0;i<factories.length;i++) {
		try {
			xmlhttp = factories[i]();
		}
		catch (e) {
			continue;
		}
		break;
	}
	return xmlhttp;
}