alt Hacker NewsIt's overwhelmingly more of an outsider talking point than an actual issue in practice. There's a category of people that just says any extensible protocol must fundamentally have massive amounts of incompatibility, and brings it up every chance they can... and while that is technically always possible, it only happens in practice if clients diverge greatly. XMPP clients mostly work together much better than Matrix clients, from what I've experienced, as long as they've been actively developed at some point in the last decade. Which is by far most clients in use.
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Don't get me wrong, I have been hearing about XMPP forever, and I would love to have an opportunity to try it. Unfortunately it hasn't happened. I have been forced to use Slack, Discord, I have had opportunities to try Matrix, Zulip, of course I have been using IRC for a long time. But XMPP? I may have installed an app, but I haven't had an opportunity to actually use it. Is there a list of communities there?
Then about it being confusing: you're right, that's an outsider point. Because I haven't been able to try it (again nobody ever told me "oh, this project is on XMPP, you can go ask your question with this app/website"), but I have been genuinely interested in it, I ended up on the official pages.
- Check the RFC list: https://xmpp.org/rfcs/#6120. The first one is more than 200 pages, the second more than 100. There are 5 "basic RFCs" and 19 "further RFCs" (whatever "further" is supposed to mean). There is no way I will even open them all. Conclusion: I have no idea how XMPP works, except that there is XML in the mix and a whole bunch of stuff around.
- There is a "technical overview" here: https://xmpp.org/about/technology-overview/. I invite you to have a look at it. Apart from the fact that it seems to use "XMPP" and "Jabber" interchangeably (I think? I'm confused), it kind of loses me at "Jingle", which seems to be a "multimedia specification" (does that mean it's for video?), and has a bunch of implementations, like "pidgin". Isn't pidgin an XMPP client? Here it's under the Jingle section. And then there are extensions, with a whole section just for "Multi User Chats": so the default is that there are no groups, and if my client supports this extension and the server supports it, then I can join a group? I gave up at "PubSub", I did not even read anything from "BOSH".
As a person who wrote his own IRC client, contributed to Signal and looked into the Matrix protocol (which seems more complex than I am comfortable with), I must say that XMPP is in its very own league.
My conclusion with Matrix was that nobody would ever want to write it from scratch, so there has to be some kind of `libmatrix` on top of which people could build. Seems hard in practice because it feels like it keeps changing.
I don't know how fast XMPP is moving, but I would hope that it is now stable. Is there a libxmpp that contains all the necessary features to write a client? Not clear to me. It feels like it's still a complex ecosystem where it depends on the client, and on the server, and on what you want to do.
> XMPP clients mostly work together much better than Matrix clients, from what I've experienced
I can only take your word on it: I don't know a community that is on XMPP, so I haven't had a chance to try. Matrix has been frustrating, that I can say.
For Matrix clients I'm given to understand the issue is the lack of XEP equivalents. Either your server(s) and clients are all on the latest available version or you're SOL. This makes third party clients effectively impossible since every change is basically a breaking change and the client and server are tightly coupled.
XMPP took it a step further and has feature segmentation by defining XEPs. This is basic minimum for defining an extensible protocol for client-server communication and has been for decades (maybe it was a new idea when XMPP first started). Notably, browsers use this same thing with w3c specs, which is why they keep working too. If you don't have this feature segmentation and negotiation, you don't have a functional open source client-server protocol full-stop (looking at you Matrix).
I think what XMPP has gotten better at is doing like with w3c and setting baseline minimum features, which has allowed more standardization of clients.