public function setType($type)
    {
        if (!in_array($type, $this->_types)) {
            require_once 'Zend/Server/Exception.php';
            throw new Zend_Server_Exception('Invalid method callback type  passed to ' . __CLASS__ . '::' . __METHOD__);
        }
        $this->_type = $type;
        return $this;
    }