Manually close Ratchet web socket server on server side?

[shin...@gmail.com]

Hello. First of all, I have use the following php code to success bind ratchet to my server.

$app = new Ratchet\App('xxx', xxx, 'xxx', null);
$app->route('/ChatServer', new ChatServer(), array('*'));
$app->run();

However, how can I manually close this chat server? Is there any code can do that?

Such as $app->close ?

Thanks.