Subject: Re: draft-ietf-httpbis-client-hints-06

From: Ilya Grigorik <[email-masked]>
Date: Sat, 4 Aug 2018 14:15:04 -0700

Hi Kari. Thanks for the feedback.

On Wed, Jul 25, 2018 at 9:14 AM HTTP Working Group <[email-masked]>
wrote:

> |   If DPR occurs in a message more than once, the last value overrides
> |   all previous occurrences.

So is that saying that if there is several DPR values on
> DPR Header Field, last value is used ?
>

Yes, that's the intent.

If that in interpreted only that if last DPR header field is used,
> and header field is ignored if it does not fit
>
>    DPR = 1*DIGIT [ "." 1*DIGIT ]
>
> syntax, result is different is recipient combines multiple
> DPR headers.

The intent was to specify that last valid value (regardless if it is within
a combined or separate header) is the one that should be used by the
client. My read of the current wording is that it matches this intent, but
I'll defer to the experts here on how to best word this if that's not the
case.

Mark, Julian: any guidance on this one?

> |   If <X> occurs in a message more than once, the last value
> |   overrides all previous occurrences.
>
> So it should mention that on these header fields also last value
> is used when values are ',' -separated.
>

My understanding is that this is implicit, but if that's not the case,
happy to rework the wording.

ty!

---

From: Julian Reschke <[email-masked]>
Date: Sun, 5 Aug 2018 09:46:49 +0200

On 2018-08-04 23:15, Ilya Grigorik wrote:
> On Wed, Jul 25, 2018 at 9:14 AM HTTP Working Group <[email-masked] 
> <mailto:[email-masked]>> wrote:
> 
> The intent was to specify that last valid value (regardless if it is 
> within a combined or separate header) is the one that should be used by 
> the client. My read of the current wording is that it matches this 
> intent, but I'll defer to the experts here on how to best word this if 
> that's not the case.
> 
> ...

No, it's not implicit, so yes, a clarification would be good.

FWIW, related issue in http-core: 
<https://github.com/httpwg/http-core/issues/111>

Best regards, Julian

---

From: Ilya Grigorik <[email-masked]>
Date: Tue, 7 Aug 2018 21:52:09 -0700

> <https://github.com/httpwg/http-core/issues/111>

Ah, interesting. Thanks for the pointer!

Obvious followup question: do we have any existing, vetted text in other
specs that I should be looking at? I can't imagine this is the first
instance of this particular problem.