public function getSitesTable($idSite)
    {
        $id = 'sitesTable#' . $idSite;

        if (empty($idSite)) {
            return $this->getNonPersistentStorage($id . '#nonpersistent');
        }

        if (!isset($this->cache[$id])) {
            $backend = new Backend\SitesTable($idSite);
            $this->cache[$id] = $this->makeStorage($backend);
        }

        return $this->cache[$id];
    }