Symfony2 session usage example analysis

$session = $this->getRequest()->getSession();
$session->set('foo', 'bar');
$foobar = $session->get('foobar');

use Symfony\Component\HttpFoundation\Request;
public function indexAction(Request $request)
{
  $session = $request->getSession();
  // store an attribute for reuse during a later user request
  $session->set('foo', 'bar');
  // get the attribute set by another controller in another request
  $foobar = $session->get('foobar');
  // use a default value if the attribute doesn't exist
  $filters = $session->get('filters', array());
}