public function notify(
        $application,
        $event,
        $description,
        $priority = 0,
        $url = '',
        $html = false
    ) {
        $this->validator
            ->validateApplication($application)
            ->validateEvent($event)
            ->validateDescription($description)
            ->validatePriority($priority)
            ->validateUrl($url);

        $this->resetApiParameters();
        $this->setCommonApiParameters();

        // required parameters
        $this->setApiParameter('application', $application);
        $this->setApiParameter('event', $event);
        $this->setApiParameter('description', $description);

        // optional parameters
        $this->setApiParameter('priority', $priority);
        if ('' !== $url) {
            $this->setApiParameter('url', $url);
        }
        if (true === $html) {
            $this->setApiParameter('content-type', 'text/html');
        }

        return $this->callApi(self::API_URL_NOTIFY);
    }