Zend Framework. Валидатор URL.

Для проверки url вида:
http://www.websites.com
http://subdomain.websites.com
http://www.websites.com/directory/
http://www.websites.com/index.php?whatever=xyz

class My_Validate_Url extends Zend_Validate_Abstract {
    const INVALID_URL = 'invalidUrl';

    protected $_messageTemplates = array(
        self::INVALID_URL => "'%value%' is not a valid URL.",
    );

    public function isValid($value) {
        $valueString = (string) $value;
        $this->_setValue($valueString);

        if (!Zend_Uri::check($value)) {
            $this->_error(self::INVALID_URL);
            return false;
        }
        return true;
    }
}

$website = $form->createElement('text', 'website');
$website->addValidator(new My_Validate_Url());