public static function getApi($api_key = NULL)
{
if (empty($api_key)) {
$api_key = Config::g('onenet_masterkey');
}
if (!is_object(self::$_apis[$api_key])) {
$master_key = Config::g('onenet_masterkey');
self::$_apis[$api_key] = new OneNetApi($api_key, Config::g('RESTfulUrl'));
}
return self::$_apis[$api_key];
}