//------------------------------------------------------------
// NlsTree connection to server using XHTMLHttpRequest
//------------------------------------------------------------

// create XMLHttpRequest object to communicate to server
function createXMLHttpRequest() {
  	if (typeof XMLHttpRequest != "undefined") { //for mozilla
    	var httpReq = new XMLHttpRequest();
    	return httpReq;
  	} 
	else {
    	var arrObj = ["MSXML2.XMLHttp.5.0", "MSXML2.XMLHttp.4.0", "MSXML2.XMLHttp.3.0", "MSXML2.XMLHttp", "Microsoft.XMHttp"];
    	var oXml   = null;
    	for (var i = 0; i < arrObj.length; i++) {
      		try {
        		oXml = new ActiveXObject(arrObj[i]);
        		return oXml;
      		} 
			catch (e) {
			}     
    	}
  	}
}

// create temporary iframe to execute from XHTMLHttpRequest object
function nlsCreateExeFrame(id) {
  	var frm = document.getElementById("exefrm_" + id);
  	if (!frm) 
		frm = document.createElement("iframe");
		
  	frm.width 		= 0; 
	frm.height 		= 0; 
	frm.frameBorder = 0;
  	frm.name		= "exefrm_" + id;
  	frm.id			= "exefrm_" + id;
  	document.body.appendChild(frm);
  
  	if (document.frames) {
    	return document.frames["exefrm_" + id];
  	} 
	else {
    	return frm.contentWindow;    
 	}
}

// remove the temporary frame
function nlsRemoveExeFrame(id) {
  	var frm = document.getElementById("exefrm_" + id);
  	if (frm) 
  		document.body.removeChild(frm);
}

function NlsXMLHttpHandler() {
  	this.tId	= null;
  	this.id		= null;
  	this.inId	= null;
  	this.xmlReq = null;
  	this.anim	= null;
  
  	var me		= this;
  	this.init	= function(mth, url, async) {
    	this.xmlReq = createXMLHttpRequest();
    	this.xmlReq.open(mth, url, true);
    	this.xmlReq.onreadystatechange = me.readystatechange;
  	}

  	function executeResult(frm) {
		frm.document.open();
      	frm.document.write(me.xmlReq.responseText);
      	frm.document.close();
      
      	nlsRemoveExeFrame(me.id);
      	if (me.inId) { 
			clearInterval(me.inId); 
			me.inId = null; 
			
			if (me.anim != null) 
				me.anim.stop(); 
		}
		
		if (me.xmlReq.status == 200 || me.xmlReq.status == 304) {
			me.resultReady_Callback(me.tId, me.id);
      	} 
		else {
        	alert("Error occur.");
      	}    
  	}
  
  	this.readystatechange = function() {
		if (me.xmlReq.readyState == 4  || me.xmlReq.readyState == "complete") {
      		var frm = nlsCreateExeFrame(me.id);
      		window.setTimeout(function() {executeResult(frm);}, 10);
    	} 
		else {
		}
  	}
  
  	this.send = function(p) {
    	if (this.anim != null) 
			this.inId = setInterval(me.anim.start, 1000);
    	this.xmlReq.send(p);
  	}
  
  	this.resultReady_Callback = function(tId, id) {
		return;
	}
}