private function create_basic_request($method) {
        $this->header_add(sprintf('%s %s %s', $method, $this->_path, $this->_protocol));
        $this->header_add(sprintf('Host: %s:%s', $this->_server, $this->_port));
        //$request .= sprintf('Connection: Keep-Alive');
        $this->header_add(sprintf('User-Agent: %s', $this->_user_agent));
        $this->header_add('Connection: TE');
        $this->header_add('TE: Trailers');
        if ($this->_auth == 'basic') {
            $this->header_add(sprintf('Authorization: Basic %s', base64_encode("$this->_user:$this->_pass")));
        } else if ($this->_auth == 'digest') {
            if ($signature = $this->digest_signature($method)){
                $this->header_add($signature);
            }
        } else if ($this->_auth == 'bearer') {
            $this->header_add(sprintf('Authorization: Bearer %s', $this->oauthtoken));
        }
    }