[Arathorn]

As far as we know, the Wire version is still logically centralised, using a centralised sequencing server.

On the Matrix side we’re working on fully decentralising it (as per https://matrix.uhoreg.ca/mls/ordering.html). There’s also a cool similar project from Matthew Weidner: https://dl.acm.org/doi/10.1145/3460120.3484542

It’s a bit perplexing that mnot’s draft cites XMPP as decentralised, given MUCs are very much centralised to a single provider which entirely controls that conversation, and if that provider goes down the conversation is dead. But I guess that’s because XMPP is submitted to the IETF, and Matrix isn’t yet.

[zaik]

XMPP is still a decentralized protocol by design. That you can't send messages to a conference hosted on a server that is offline doesn't make it 'centralized'.

[Arathorn]

There are probably five broad levels of decentralisation here:

1. Open network, but each user lives on a single server, each conversation is dependent on a single server: (XMPP MUCs)

2. Open network, but each user lives on a single server (with some ability to manually migrate between servers), conversations are replicated across all participating servers: (Matrix, ActivityPub, SMTP, NNTP)

3. Open network, users are replicated across multiple servers, conversations are replicated across all participating servers: (Matrix + MSC1228 or MSC2787 or similar)

4. Open network, users live on a single P2P node, conversations are replicated across all participating nodes: (Briar, today's P2P Matrix)

5. Open network, users are replicated across multiple P2P nodes, conversations are replicated across all participating nodes: (P2P Matrix + MSC2787 etc).

So yes, XMPP is decentralised by some definition, but it's kinda useful to map out the whole space.