[Standards] XEP-0045 join when already in MUC

Daurnimator quae at daurnimator.com
Mon Jun 27 07:34:28 UTC 2016

On 24 June 2016 at 16:55, Kevin Smith <kevin.smith at isode.com> wrote:
>> 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 the key point here is that the *client* gets to see all the
things they normally would when joining.
For the other occupants in the room they may see just a presence
update, or if the presence is the same: nothing.

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