function crearXMLHttpRequest()
{
  var xmlHttp=null;
  if (window.ActiveXObject)
    xmlHttp = new ActiveXObject("Microsoft.XMLHTTP");
  else
    if (window.XMLHttpRequest)
      xmlHttp = new XMLHttpRequest();
  return xmlHttp;
}

function Ajax (controlador,accion,capa,valores,metodo){

  var navurl = document.location.href;
  var domain = navurl.split('/');
  var url = domain[0] + '//' + domain[2] + '/' + controlador + '/' + accion; 
  var ajax=crearXMLHttpRequest();
  var capaContenedora = document.getElementById(capa);
  
  //alert(url);

  /*Creamos y ejecutamos la instancia si el metodo elegido es POST*/ 
  if(metodo.toUpperCase()=='POST'){
    ajax.open ('POST', url, true);
    ajax.onreadystatechange = function() {
      if (ajax.readyState==1) {
        capaContenedora.innerHTML="";
      }else if (ajax.readyState==4){
        if(ajax.status==200){
          document.getElementById(capa).innerHTML=ajax.responseText;
        }else if(ajax.status==404){
          capaContenedora.innerHTML = "La direccion no existe";
        }else{
        capaContenedora.innerHTML = "Error: "+ajax.status;
        }
      }
    }
    ajax.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
    ajax.send(valores);
    return;
  }

  /*Creamos y ejecutamos la instancia si el metodo elegido es GET*/
  if (metodo.toUpperCase()=='GET'){
    ajax.open ('GET', url, true);
    ajax.onreadystatechange = function() {
      if (ajax.readyState==1) {
        capaContenedora.innerHTML="";
      }else if (ajax.readyState==4){
        if(ajax.status==200){
          document.getElementById(capa).innerHTML=ajax.responseText;
        }else if(ajax.status==404){
          capaContenedora.innerHTML = "La direccion no existe";
        }else{
          capaContenedora.innerHTML = "Error: "+ajax.status;
        }
      }
    }
    ajax.setRequestHeader('Content-Type','application/x-www-form-urlencoded');
    ajax.send(null);
    return
  }
}