public function init($id, $name, $lifetime, $maximumAge, $domain, $path, $secure, $httpOnly, $lastActivityTimestamp = null)
    {
        // initialize the session
        $this->id = $id;
        $this->name = $name;
        $this->lifetime = $lifetime;
        $this->maximumAge = $maximumAge;
        $this->domain = $domain;
        $this->path = $path;
        $this->secure = $secure;
        $this->httpOnly = $httpOnly;

        // the UNIX timestamp where the last action on this session happens
        if ($lastActivityTimestamp == null) {
            $this->lastActivityTimestamp = time();
        } else {
            $this->lastActivityTimestamp = $lastActivityTimestamp;
        }
    }