protected function cron_execute() {

        try {
            $this->restore_response();
            $previous = $this->recentresponse;
            $this->fetch();
            $this->restore_response(true);
            $current = $this->recentresponse;
            $changes = $this->compare_responses($previous, $current);
            $notifications = $this->cron_notifications($changes);
            $this->cron_notify($notifications);
            $this->cron_mtrace('done');
        } catch (checker_exception $e) {
            $this->cron_mtrace('FAILED!');
        }
    }