Auth_OpenID_AuthRequest::redirectURL PHP Method

    function redirectURL($realm, $return_to = null, $immediate = false)
    {
        $message = $this->getMessage($realm, $return_to, $immediate);
        if (Auth_OpenID::isFailure($message)) {
            return $message;
        }
        return $message->toURL($this->endpoint->server_url);
    }

 private function issueOpenid1Connexion(Auth_OpenID_AuthRequest $auth_request, $redirect_url)
 {
     $redirect_url = $auth_request->redirectURL($this->getTrustRoot(), $this->getReturnTo($redirect_url));
     if (Auth_OpenID::isFailure($redirect_url)) {
         throw new OpenId_OpenIdException($GLOBALS['Language']->getText('plugin_openid', 'error_openid_connect'));
     }
     header("Location: " . $redirect_url);
 }