public function registerApplication() 
    {
        $options = $this->config->getAppConfiguration();
        $credentials = $this->getResponse(
            '/api/'.ConfigurationVO::API_VERSION.'/apps',
            $options
        );
        if (isset($credentials["client_id"])
            && isset($credentials["client_secret"])
        ) {
            $this->config->setClientId($credentials['client_id']);
            $this->config->setClientSecret($credentials['client_secret']);
        }else {
            echo 'ERROR: no credentials in API response';
        }
    }