Subject: Re: Comments on draft-ietf-conneg-feature-syntax-01.txt

From: Graham Klyne <[email-masked]>
Date: Fri, 13 Nov 1998 09:28:38 +0000

At 14:31 12/11/98 +0100, Koen Holtman wrote:

>I think the way to resolve this is to state explicitely in the
>-syntax- draft that the work makes no prescriptions *at all* about q
>value semantics, and that this is left completely to individual
>negotiation procotocols.  After this statement some protocols which do
>make prescriptions (like http and TCN) could be discussed or
>referenced.

I believe it is helpful to indicate a range of values, and the fact that
higher values indicate greater levels of preference.  I think both of these
statements are without loss of generality in terms of what further
semantics can be applied.  I think the default value in the absence of an
explicit value is helpful.

Beyond that, I believe the revised wording makes it clear that no further
prescription is implied, and that further interpretation is subject to an
appropriately defined context.

>The current apache negotiation algorithm is described at
>http://www.apache.org/docs/content-negotiation.html . It multiples
>source quality with mime type quality, but does not perform
>calculations on other quality values (e.g. language quality), probably
>because at the time the code was written browsers did not send quality
>factors on languages etc (I do not know if many do now).

I've added a citation "Apache content negotiation algorithm" with that URL.

#g

------------
Graham Klyne
([email-masked])

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From: Al Gilman <[email-masked]>
Date: Fri, 13 Nov 1998 08:23:27 -0500 (EST)

> explicit value is helpful.

I second that.

Al

I also believe it might be useful to state explicitly that q=0
should be treated as "categorically unacceptable."

---

From: [email-masked] (Koen Holtman)
Date: Fri, 13 Nov 1998 19:24:13 +0100 (MET)

>explicit value is helpful.

I agree that defining these things would not constrain things too much
and might promote greater interoperability in the long term.

>appropriately defined context.

The revised wording you posted is an improvement but I think it still
mixes up the definition of q values too much with the referencing to
2068.  I would very much like to see a completely self-contained
definition consisting of 

 - syntax of common representation for ascii-based negotiation
   frameworks (same as in http)
 - definition of range (0-1)
 - definition of default value (1)
 - discussion of the limited semantics ('ordering, less is worse').
 - declaration that specific protocols may extend the semantics
   defined here

and with all discussion of use in other protocols, the
difficulties of combining, etc, in *other* sections (maybe
subsections).

>#g

Koen.