[Standards] 0174 Serverless Messaging: Discovering Capabilities

Christian Schudt christian.schudt at gmx.de
Mon Mar 5 22:37:12 UTC 2018


I find the whole passage „Discovering Capabilities“ of Serverless Messaging [1] a bit confusing.

1. Why can’t the receiving entity include its Entity Caps as stream feature as described in [2].

2. I can see the slight optimization of including disco#info data as stream feature (similar as with including Entity Caps), but the reasoning here is far-fetched: "full stream negotiation already can require a large number of packets“.
(a) Stream negotiation should already be less expensive than in a real client-to-server session and
(b) I can’t imagine that a single additional IQ-get request for disco#info would have a performance impact in a serverless messaging environment or would justify the additional implementation complexity:

3. disco#info as stream feature adds unnecessary burden to developers, which must now:
- Deal with Entity Caps in TXT records (publish and read Entity Caps to/from another source)
- Check stream features not only for Entity Caps, but also for disco#info.
(otherwise we could simply reuse existing logic from [2])

Am I missing something here?
What are your thoughts about it?
Can the section be updated although the specification is final?

— Christian

[1]: https://xmpp.org/extensions/xep-0174.html#caps
[2]: https://xmpp.org/extensions/xep-0115.html#stream

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