jdev - 2026-08-24

hi, i'm reading through the muc spec and noticed that joining a room inherently causes the server to send the presences of all of the room occupants. is there a way to skip this? i fear that for very large rooms (think +10k) it would be a huge waste of bandwidth

i think ejabberd does this after a certain point, however the network is small enough that this isnt a super huge concern in most use cases

darkuss: you might be interested in https://xmpp.org/extensions/xep-0436.html but it isn't implemented anywhere AFAIK. it is possible to not send presences at all, and just send a presence when someone actually speaks. FWIW, in slidge (gateways) for large groups I generally limit to 100 participants, priorizing owners/admins and those who spoke recently. When someone speaks, if no presence was ever sent by this participant, I send one before the first message. This is particularly relevant for huge groups, like they have in discord, matrix, mattermost or telegram.

tldr: not much breaks client-list if you don't send the full list of participants on join.

ic

note that most clients will also fetch affiliations after joining when it's a private group, and https://xmpp.org/extensions/xep-0463.html reduces the round-trips for that

there is a prosody module that supports that, dino and movim have worked on implementations too, I am not sure if that has been merged/released yet. slidge does support it too. none of these implementations actually do proper versioning with diff, but if affiliations don't change it's already a noticeable optimisation. and even without that, it reduces roundtrips. ✏

Hi so, group calls in xmpp are not a thing, right?

They are, through Muji

I saw the xepp but does anything implement it?

dino does

https://files.isekai.rocks/file_share/01a034c8-8d66-719c-a3b3-5ff022f226ec/08c40386-13b5-4188-b78b-35b0f0d2f6f0.png

and movim apparently

Will have to test it, thanks!