private function getSetting($serviceName, $variable) {
        // make sure there are settings for the service
        if (!isset($this->settings[$serviceName])) {
            $this->settings[$serviceName] = array(
                'maxFailures' => $this->defaultMaxFailures,
                'retryTimeout' => $this->defaultRetryTimeout,
            );
        }
        return $this->settings[$serviceName][$variable];
    }