public function send()
    {
        if (headers_sent()) {
            /** 
             * @see Zend_Feed_Exception
             */
            require_once 'Zend/Feed/Exception.php';
            throw new Zend_Feed_Exception('Cannot send ATOM because headers have already been sent.');
        }

        header('Content-Type: application/atom+xml; charset=' . $this->_element->ownerDocument->actualEncoding);

        echo $this->saveXML();
    }