If the publisher is a server, it **SHOULD** advertise the URL of one or more hubs to the subscriber, allowing it to receive live updates when topics are updated.
If more than one hub URL is specified, it is expected that the publisher notifies each hub, so the subscriber **MAY** subscribe to one or more of them.
@@ -81,6 +83,8 @@ Note: the discovery mechanism described in this section [is strongly inspired fr
The subscriber subscribes to an URL exposed by a hub to receive updates of one or many topics.
To subscribe to updates, the client opens an HTTPS connection following the [Server-Sent Events specification](https://html.spec.whatwg.org/multipage/server-sent-events.html) to the hub's subscription URL advertised
by the Publisher. The `GET` HTTP method must be used.