Re: [Masque] Prioritizing HTTP DATAGRAMs

Hi, Lucas,

On Tue, Jun 22, 2021 at 8:40 AM Lucas Pardue <lucaspardue.24.7@gmail.com>
wrote:

> Hello HTTP and MASQUE,
>
> Over the last couple of months, the question about prioritization with
> respect to HTTP DATAGRAMs has come up first in MASQUE issue # 46 [1] and
> then HTTP issue #1550 [2], which was also discussed during the recent HTTP
> interim.
>
> Extensible priorities is pretty far along it's journey, which has so far
> been focused on HTTP message content (and CONNECT tunnel data, see PR #1544
> [3]). The scheme fulfills the needs of the base HTTP/2 and HTTP/3
> specifications, and so far hasn't considered extensions. Extensible
> priorities acts as a replacement for HTTP/2's prioritization scheme, while
> being the only known scheme defined for HTTP/3. However, there is nothing
> to prevent alternate schemes being defined or used in the future (although
> we hope the need for that can be avoided by the extensibility here).
>
> Endpoints that send DATAGRAM flows concurrently with other flows or
> streams have to make scheduling decisions. Therefore, the question about
> how to prioritize them, and to communicate that via signals, is a good one.
> However, currently the editors of draft-ietf-masque-h3-datagram and
> draft-ietf-httpbis-priority (disclosure: I am co-editor on both) feel that
> linking these two drafts directly is not the best approach for either.
>
> On draft-ietf-masque-h3-datagram issue #46 [1], we resolved the discussion
> by adding text to say that prioritization of HTTP/3 datagrams is not
> defined by the document.
>
> For draft-ietf-masque-h3-datagram issue #1550 [2], the proposed resolution
> is PR #1559 [4]. The PR adds a clear statement that the document is focused
> on HTTP content and CONNECT tunnel data. It also makes clear that
> extensions like DATAGRAM can also use the scheme but punts that to their
> court.
>
> Kazuho and I are seeking some feedback for PR #1559 [4] before landing it.
> We appreciate that this leaves a gap for DATAGRAM priorities, especially
> since DATAGRAM says nothing. But the thought process is that another
> Internet-Draft could fill this gap. This would create an indirect
> relationship that would allow documents to progress independently. I'm
> planning to start a draft soon and have it ready by IETF 111. Which WG it
> should belong to is probably another matter for debate.
>

What follows is certainly off-topic for HTTPbis, and probably for MASQUE as
well, but if it's worth talking about, you'd know better where we should
talk about it.

I believe that
https://datatracker.ietf.org/doc/draft-hurst-quic-rtp-tunnelling/ was
bumping up against the desire to use QUIC datagrams for tunneling and the
recognition that we don't have an agreed-upon way to multiplex (and
demultiplex) datagrams that are carried in the same QUIC connection.

Do you see any connection between prioritizing datagrams and
multiplexing/demultiplexing datagrams?

Best,

Spencer

> Cheers
> Lucas
> Wearing co-editor hat for HTTP/3 DATAGRAM and Extensible priorities
>
>
> [1]
> https://github.com/ietf-wg-masque/draft-ietf-masque-h3-datagram/issues/46
> [2] https://github.com/httpwg/http-extensions/issues/1550
> [3] https://github.com/httpwg/http-extensions/pull/1544
> [4] https://github.com/httpwg/http-extensions/pull/1559
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