how Get DI services From anyWhere

//  public/index.php
define('BASE_DIR', dirname(__DIR__));
define('APP_DIR', BASE_DIR . '/app');

include APP_DIR . "/config/initialize.php";
$application = new \Phalcon\Mvc\Application($di);
$di['app'] = $application; //  Important
//require_once("../app/library/snowair/phalcon-debugbar/src/ServiceProvider.php");
if ($config->get("application", "environnement") == "production") {
    ini_set('display_errors', 'Off');
    error_reporting(0);
}
else {
    new \Whoops\WhoopsServiceProvider($di);
}

echo $application->handle()->getContent();

// app/config/service.php
$di = new Phalcon\DI\FactoryDefault();
$di->set('session', function() {
    $session = new Phalcon\Session\Adapter\Files();
    if (!isset($_SESSION)) {
        $session->start();
    }
    return $session;
});

// app/controllers/ClassController.php

function updateAction()
{
        Helpers\Famille::updateTaux();
}

// app/componets/helpers/Famille.php
abstract class Famille {

    abstract static function updateTaux()
    {
        // $this is undefined 
        //How can I get the service Session 
    }
}

I want to call the service session into my class Famille . How can I get it ? Thanks !