//This javascript is used to validate username

//generate XMLHttpRequest Object
	var usernamexmlrequest;
	var usernameComponent;//user name component ,it maybe a input component.
function newXMLHttpRequest() {
  var xmlreq = false;  
  if (window.XMLHttpRequest) {  
    xmlreq = new XMLHttpRequest();
  } else if (window.ActiveXObject) {
  
    try {    
      xmlreq = new ActiveXObject("Msxml2.XMLHTTP");      
    } catch (e1) {
    
      try {
        xmlreq = new ActiveXObject("Microsoft.XMLHTTP");
      } catch (e2) {
      }
    }
  }
  return xmlreq;
}
//send a request to server with url
function sendRequestToServer(url)
{	//alert(url);
	usernamexmlrequest=newXMLHttpRequest();
	usernamexmlrequest.onreadystatechange=validUserNameCallback;
	usernamexmlrequest.open("get",url,true);
	usernamexmlrequest.send(null);
}
//if username is validate then return YES
// if not validate then return NO
function validUserNameCallback(){
	if(usernamexmlrequest.readyState==4){
		if(usernamexmlrequest.status==200){
			dealResponse(usernamexmlrequest.responseText);
		}
	}
}
function dealResponse(res){
	if(res=="NO"){
		usernameComponent.value="";
		document.getElementById("10112").style.display="";
	}
}
function validateUserNameIsUseful(context,userComponent){
	usernameComponent=userComponent;
	var username=userComponent.value;
	if(""==username || null==username){
		return;
	}else{
		var url=context+"/servlet/validate?username="+username;
		//alert(url);
		sendRequestToServer(url);
	}
}