protected function build_rest_url($url, $params = array()) {
        $base = '';
        if (substr($this->_url, 0, 4) !== 'http') {
            $base .= 'http://';
        }

        $base .= $this->_url;
        if ($this->_port != 80) {
            $base .= ':' . $this->_port;
        }

        $rurl = new \Rapid\URL($base . '/api/' . $url, $params);
        return $rurl->out();
    }