[Standards] XEP-0289 FMUC: Do joined nodes know what mode is configured?

Guus der Kinderen guus.der.kinderen at gmail.com
Thu May 7 12:19:21 UTC 2020

I've had some one-on-one conversations which lead me to believe that
expecting the joined FMUC node to echo a stanza back in master-slave mode,
but not in master-master mode, is something that's not adequately covered
in the XEP. Assuming that this indeed is an oversight, I'd like to work
towards a fix. I'll offer a few suggestions:

a) Somehow negotiate the configuration mode between both nodes.
b) Have the joining node include a flag on each stanza it sends to the
joined node that signals whether a callback is desired or not
c) Have the joined node include a flag on a stanza that is echoed back,
indicating that it is an echo (a 'status 110'-like solution).
d) Have the joining node persist each stanza that it sends to the joining
node, allowing it to evaluate each inbound stanza to determine if it's an


On Mon, 4 May 2020 at 12:53, Guus der Kinderen <guus.der.kinderen at gmail.com>

> Hello all,
> A XEP-0289 FMUC question, related to section 5.2 (
> https://xmpp.org/extensions/xep-0289.html#messages ).
> The example describes how a joining FMUC node (elsinore) sends a message
> to the joined FMUC node (rabbithole). Federation is configured to use the
> master-slave mode (where rabbithole is the master). This sentence makes me
> wonder if I misunderstand a key part of the XEP:
> This example is for master-master mode, so rabbithole does not echo the
>> message back to elsinore and elsinore does not need to wait for receipt of
>> this stanza from rabbithole (...)
> As I understand the XEP, the federation is initiated by elisnore. This is
> where the configuration lives. No negotiation of the configuration
> (specifically, the type of mode that's used) seems to take place. This is
> also referenced to in section 5.1:
> Note that this configuration only needs to be one way (that is: there is
>> no protocol reason why rabbithole needs to know that elsinor will be
>> federating with it in advance)
> How does rabbithole determine that it needs not echo the message back to
> elsinore?
> Regards,
>   Guus
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