protected function findSessionId()
	{
		// check for a posted session id
		if ( ! empty($this->config['post_cookie_name']) and isset($_POST[$this->config['post_cookie_name']]))
		{
			$this->sessionId = $_POST[$this->config['post_cookie_name']];
		}

		// else check for a regular cookie
		elseif ( ! empty($this->config['enable_cookie']) and isset($_COOKIE[$this->name]))
		{
			$this->sessionId = $_COOKIE[$this->name];
		}

		// else check for a session id in the URL
		elseif (isset($_GET[$this->name]))
		{
			$this->sessionId = $_GET[$this->name];
		}

		// TODO: else check the HTTP headers for the session id

		return $this->sessionId ?: null;
	}