Re: SETTINGS_ENABLE_HTTP2_PRIORITIES default value | Re: Setting to disable HTTP/2 Priorities

Willy Tarreau <w@1wt.eu> Thu, 01 August 2019 04:43 UTC

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Date: Thu, 1 Aug 2019 06:41:08 +0200
From: Willy Tarreau <w@1wt.eu>
To: Lucas Pardue <lucaspardue.24.7@gmail.com>
Cc: Kari Hurtta <hurtta-ietf@elmme-mailer.org>, HTTP Working Group <ietf-http-wg@w3.org>, Brad Lassey <lassey@chromium.org>
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Subject: Re: SETTINGS_ENABLE_HTTP2_PRIORITIES default value | Re: Setting to disable HTTP/2 Priorities
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On Wed, Jul 31, 2019 at 08:14:24PM +0100, Lucas Pardue wrote:
> > If initial value for SETTINGS_ENABLE_HTTP2_PRIORITIES is really 1,
> > then peer may assume that other ends supports HTTP/2 priorities
> > until SETTINGS_ENABLE_HTTP2_PRIORITIES is seen.
> >
> > So there is inconsistence between chapters.
> >
> > / Kari Hurtta
> >
> 
> Agreed. We should tighten this up for something that is practically
> deployable and meets the needs of implementers. Ideally we can take
> feedback so far and iterate through the design team process.

I think the confusing part comes from the ENABLE word in the setting
name. We could proceed differently by exchanging a supported model
for priorities :  SETTINGS_HTTP2_PRIORITY_MODEL
It could then take the following values :

    0 (default) : as specified in RFC7540
    1           : priorities not sent and silently ignored
    2 and above : to be documented in future specifications

This way it seems more natural to consider that unless advertised, we
stay on RFC7540 and nothing changes.

Willy