Oddbean new post about login | logout Ah I didn't know that Signal used XMPP. It was also called "jabber" before. Anyhow, it's just an event bus system, like Nostr, with a narrow band not broadcast. There's two ways to do multi party, one is with a relay, the other is using multicast. Really they are just specific cases of network protocol. One could easily extend Nostr to do both types of messaging.