function check(){
	if (validate()==false) return false;
	var xml=loadData("UserInfo.xml");
	var name=document.frmLogin.elements["username"].value;
	var password=document.frmLogin.elements["password"].value;
	var node=xml.selectSingleNode("/users//user[@name=\"" + name + "\"]");	
	if (node){
		if(node.attributes.getNamedItem("password").value==password){
			SetCookie("cUsername", name);
			SetCookie("cPassword", password);
			window.open("ELET6301.htm","_self");
			}
		else {
			document.getElementById('lblErrorTip').innerHTML="Password error!";
			document.frmLogin.elements["password"].value="";
			document.frmLogin.elements["password"].focus();
			}
		}
	else{ 
		document.getElementById('lblErrorTip').innerHTML="Username does not exist!";
		document.frmLogin.elements["username"].value="";
		document.frmLogin.elements["password"].value="";
		document.frmLogin.elements["username"].focus();
		}
}

function validate()
{ 
	if ((document.frmLogin.elements["username"].value) == ''){
		document.getElementById('lblErrorTip').innerHTML="Username can't be empty!";
		document.frmLogin.elements["username"].focus();
		return false; 
	}
	if (document.frmLogin.elements["password"].value== ''){
		document.getElementById('lblErrorTip').innerHTML="Password can't be empty!";
		document.frmLogin.elements["password"].focus();
		return false; 
	}	
	return true;
}

function loadData(xmlSource){
	var xml = createXMLDom();
	xml.async=false;
	if (xml.load(xmlSource)){
		return(xml);
	}
}

var createXMLDom=function(){
	if (window.ActiveXObject) 
		var xmldoc=new ActiveXObject("Microsoft.XMLDOM");
	else 
		if (document.implementation&&document.implementation.createDocument)
			var xmldoc=document.implementation.createDocument("","doc",null);
	xmldoc.preserveWhiteSpace=true;
	return xmldoc;
	}

function SetCookie(sName, sValue){
	document.cookie = sName + "=" + escape(sValue) + "; " ;
}