WebSub query

Dear Social Web Working Group,

I just saw your recently updated https://www.w3.org/TR/websub/ spec.

It appears that the only URI scheme that is clearly supported for sending data back to subscribers is https: (or http:). Did you consider the possibility of supporting a WebSocket URI with wss: or ws: with a more realtime connection lifecycle model, rather than requiring a separate HTTP callback?

That would be very useful in a variety of use cases, for example messaging or status updates for real time events (e.g. sports game scores, electoral counts etc). The particular use case I have in mind is for live captioning/subtitling.

However I realise I may have somewhat misunderstood the intent of the spec: it would be very useful to have some more descriptive text in §5. Publishing. I see that the current wording "The hub and the publisher can agree on any mechanism, as long as the hub is eventually able send the updated payload to the subscribers." potentially allows for other possibilities, though I am not clear how the hub is expected to send the updated payload to the subscribers -  an HTTP POST to the subscriber callback URLs perhaps?

Looking forward to learning more about this interesting spec,

Kind regards,

Nigel

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Nigel Megitt
Executive Product Manager, BBC Design & Engineering
Telephone: +44 (0)3030807996
BC2 C1 Broadcast Centre, Media Village, 201 Wood Lane, London W12 7TP