function validaSesion(){
	var tiempo = new Date();
	var param = "tiempo="+tiempo.getTime();
	var reply = new Ajax.Request(
		'/sesiones.php',
		{
		method: 'get',
		parameters: param,
		onLoading: mostrarLoading,
		onComplete: function (reply) {
			mostrarDatos (reply);
			if ($('contenedorDownload'))
			{
				mostrarDownload ();
			}
		}
		}
	);
}

function validaUsuario(urlReferer){
	var param = Form.serialize('formLogin');
	var reply = new Ajax.Request(
		'/sesiones.php',
		{
		method: 'post',
		parameters: param,
		onComplete: function(reply) {
				if (reply.responseText == "ok")
				    document.location.href = urlReferer;
				else
                    mostrarDatosLogin(reply);
			}
		}
	);
}

function logout(){
	var param = "logout=true";
	new Ajax.Request(
		'/sesiones.php',
		{
		method: 'get',
		parameters: param,
		onLoading: mostrarLoading,
		onComplete: function() {
			validaSesion ();
			if ($('contenedorComentariosDatos'))
				$('contenedorComentariosErrores').innerHTML = "";
			}
		}
	);
}

function mostrarLoading(){
	$('contenedorDatos').innerHTML = "";
	$('contenedorLoading').innerHTML = "<img src='/images/loading_content.gif' />";
}
function mostrarDatos(reply){
	$('contenedorLoading').innerHTML = "";
	$('contenedorDatos').innerHTML = reply.responseText;
}
function mostrarDatosLogin(reply){
	$('contenedorDatosLogin').innerHTML = "";
	$('contenedorDatosLogin').innerHTML = reply.responseText;
}