function makeRequest(url, requestType, data, target) 
{
	var http_request = false;
	if (window.XMLHttpRequest) { // Mozilla, Safari, ...
		http_request = new XMLHttpRequest();
	} else if (window.ActiveXObject) { // IE
		try {
			http_request = new ActiveXObject("Msxml2.XMLHTTP");
		} catch (e) {
			try {
				http_request = new ActiveXObject("Microsoft.XMLHTTP");
			} catch (e) {}
		}
	}
	if (!http_request) {
		alert('Cannot create an XMLHTTP instance');
		return false;
	}
	http_request.onreadystatechange = function() { target(http_request); };
	http_request.open(requestType, url , true);
	http_request.send(data);
}
 
function helper_getData(root, tagName) 
{
	var elementCollection = root.getElementsByTagName(tagName);
	if(elementCollection.length == 0) return null; // Opera
	var child = elementCollection[0].firstChild;
	if(child == null) return null; // MSIE + Mozilla
	return child.data;
}