public function dump($filename)
    {
        if ($this->_wsdl !== null) {
            return $this->_wsdl->dump($filename);
        } else {
            /**
             * @see Zend_Soap_AutoDiscover_Exception
             */
            require_once "Zend/Soap/AutoDiscover/Exception.php";
            throw new Zend_Soap_AutoDiscover_Exception("Cannot dump autodiscovered contents, WSDL file has not been generated yet.");
        }
    }