function formMarkup($realm, $return_to=null, $immediate=false,
                        $form_tag_attrs=null)
    {
        $message = $this->getMessage($realm, $return_to, $immediate);

        if (Auth_OpenID::isFailure($message)) {
            return $message;
        }

        return $message->toFormMarkup($this->endpoint->server_url, $form_tag_attrs);
    }