function toMessage($message, $request = null)
    {
        $implicit = $message->isOpenID1();
        $added = $message->namespaces->addAlias($this->ns_uri,
                                                $this->ns_alias,
                                                $implicit);

        if ($added === null) {
            if ($message->namespaces->getAlias($this->ns_uri) !=
                $this->ns_alias) {
                return null;
            }
        }

        if ($request !== null) {
            $message->updateArgs($this->ns_uri,
                                 $this->getExtensionArgs($request));
        } else {
            $message->updateArgs($this->ns_uri,
                                 $this->getExtensionArgs());
        }
        return $message;
    }