function enviaPost(parametros, modo){
	xmlHttp=GetXmlHttpObject(stateChanged);
	xmlHttp.open("POST", url , modo);
	xmlHttp.setRequestHeader("Cache-Control","no-store, no-cache, must-revalidate");
	xmlHttp.setRequestHeader("Cache-Control","post-check=0, pre-check=0");
	xmlHttp.setRequestHeader("Pragma", "no-cache");
	xmlHttp.setRequestHeader('Content-Type', 'application/x-www-form-urlencoded;');
	xmlHttp.send(parametros);
}
/*
quanto ao parametro modo
true - assíncrono - execução paralela
false - sincrono = execução aguarda o carregamento antes de executar a próxima instrução
*/
function enviaGet(modo){
	xmlHttp=GetXmlHttpObject(stateChanged);
	xmlHttp.open("GET", url , modo);
	xmlHttp.setRequestHeader("Content-Type", "text/html; charset=UTF-8");
	xmlHttp.send(null);
}
function GetXmlHttpObject(handler){ 
	var objXmlHttp=null
	
	if (navigator.userAgent.indexOf("Opera")>=0){
		alert("This example doesn't work in Opera");
		return;
	}
	if (navigator.userAgent.indexOf("MSIE")>=0){ 
		var strName="Msxml2.XMLHTTP";
		if (navigator.appVersion.indexOf("MSIE 5.5")>=0){
			strName="Microsoft.XMLHTTP";
		} 
		try	{ 
			objXmlHttp=new ActiveXObject(strName)
			objXmlHttp.onreadystatechange=handler; 
			return objXmlHttp;
		} 
		catch(e){ 
			alert("Error. Scripting for ActiveX might be disabled"); 
			return 
		} 
	} 
	if (navigator.userAgent.indexOf("Mozilla")>=0){
		objXmlHttp=new XMLHttpRequest();
		objXmlHttp.onload=handler;
		objXmlHttp.onerror=handler; 
		return objXmlHttp;
	}
} 
/*function GetXmlHttpObject(handler)
		{
			var vAjax;
			
			var objIE = ["MSXML2.XMLHttp.6.0", 
							"MSXML2.XMLHttp.5.0", 
							"MSXML2.XMLHttp.4.0", 
							"MSXML2.XMLHttp.3.0", 
							"MSXML2.XMLHttp", 
							"Microsoft.XMLHttp"];
							
			if (window.XMLHttpRquest){// mozila, safari
				vAjax = new XMLHttpRequest();
				vAjax.onload = handler;
				vAjax.onerror = handler; 
			}else if (window.ActiveXObject){ // IE
				var n = objIE.length;
				
				for (var i = 0; i < n; i++){
					try{
						vAjax = new ActiveXObject(objIE[i]);
						vAjax.onreadystatechange = handler; 
						break;
					} catch (err){
						vAjax =  false;
					}// catch
				}// for
			}else{
				vAjax =  false; // quando browser não suporta HMLHTTP
			}
			return vAjax;
		}*/