var net = new Object();
 
net.READY_STATE_UNINITIALIZED=0; 
net.READY_STATE_LOADING=1; 
net.READY_STATE_LOADED=2; 
net.READY_STATE_INTERACTIVE=3; 
net.READY_STATE_COMPLETE=4; 
 
// Constructor
net.CargadorContenidos = function(url, funcion, funcionError, metodo, parametros, contentType) 
{
  this.url = url;
  this.req = null;
  this.onload = funcion;
  this.onerror = (funcionError) ? funcionError : this.defaultError;
  this.cargaContenidoXML(url, metodo, parametros, contentType);
}
 
net.CargadorContenidos.prototype = 
{
  cargaContenidoXML: function(url, metodo, parametros, contentType) 
  {
    if (window.XMLHttpRequest) 
	{
      this.req = new XMLHttpRequest();
    } 
	else if (window.ActiveXObject) 
	{
      this.req = new ActiveXObject("Microsoft.XMLHTTP");
    }
 
    if(this.req) 
	{
      try 
	  {
        var loader = this;
        this.req.onreadystatechange = function() 
		{
          loader.onReadyState.call(loader);
        }
        this.req.open(metodo, url, true);
        if(contentType) 
		{
          this.req.setRequestHeader("Content-Type", contentType);
        }
        this.req.send(parametros);
      } 
	  catch (err) 
	  {
      	this.onerror.call(this);
      }
    }
  },
 
  onReadyState: function() 
  {
    var req = this.req; 
    var ready = req.readyState; 
    if (ready == net.READY_STATE_COMPLETE) 
	{ 
      var httpStatus = req.status; 
      if(httpStatus == 200 || httpStatus == 0) 
	  { 
        this.onload.call(this);
      }
      else 
	  {
        this.onerror.call(this);
      }
    }
  },
 
  defaultError: function() 
  {
    alert("Se ha producido un error al obtener los datos"
      + "\n\nreadyState:" + this.req.readyState
      + "\nstatus: " + this.req.status
      + "\nheaders: " + this.req.getAllResponseHeaders());
  }
}