[Standards] Proposed XMPP Extension: Fallback Indication

Marvin W xmpp at larma.de
Wed Jan 8 15:04:37 UTC 2020

On 1/8/20 3:37 PM, Georg Lukas wrote:
> Having a per-namespace trigger isn't possible
> because <fallback> doesn't tell us for which specific payload this is
> a fallback.

I also feel that for fallback indication to be useful, namespace of what
this is a fallback for should be added.

This would also allows servers to discover (via service discovery) if
the receiving client does support a protocol and strip out the fallback
body (and the fallback hint) for clients that do, saving a few bytes on
the wire. It might be a tiny optimization, but why not?

Another thing is that IMO it should be possible to indicate a begin/end
of the fallback in the body, if the body only partially contains
fallback. The example I have in mind is a reply feature, where the
replied-to message is provided using a <reply-to id="message-id" /> and
the body contains a quote of the message for fallback compatibility, but
clients that do understand the <reply-to> probably don't want to display
that part (and instead just nicely reference the message "message-id"
somehow). Just an idea, but if we have any indication of a fallback in
the body, it should cover that use-case.


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