[Standards] XEP-0045 join when already in MUC

Kevin Smith kevin.smith at isode.com
Fri Jun 24 06:55:44 UTC 2016

> On 23 Jun 2016, at 23:35, Georg Lukas <georg at op-co.de> wrote:
> Hi,
> TL;DR: whenever a client (re)sends a join, the MUC service should return
> everything a newly joining client needs to know.
> According to XEP-0045, an initial join presence needs to contain an 'x'
> element with 'http://jabber.org/protocol/muc' namespace (§7.2.2),
> whereas a regular presence update to the MUC does not (§7.7).
> In §7.2.3 it follows up then with "If the service is able to add the
> user to the room, it MUST send presence from all the existing
> participants' occupant JIDs to the new occupant's full JID, ..."
> I would like to propose the following add-on clarification:
> "The service MUST send to the client everything that would be sent on a
> join even if the user already is joined to the MUC with the same full
> JID. This is required because a client (or the user's server) might have
> been restarted without informing the MUC by means of an 'unavailable'
> presence.”

I think you’re claiming (and I think I agree) that the proposed text is repeating the existing rule in more obvious terms. The implication of this being that this wouldn’t need any sort of namespace bump or the suchlike.

For what it’s worth, M-Link has had this behaviour since more or less the year dot, and the only downside I can recall seeing in that time is that Google had a bug where they repeated presence periodically, causing continual rejoins.

I think it’d be a useful change to the spec (although I’d quibble slightly about the wording).


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