Re: #428 Accept-Language ordering for identical qvalues

Mark Nottingham <mnot@mnot.net> Mon, 28 January 2013 03:14 UTC

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From: Mark Nottingham <mnot@mnot.net>
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Date: Mon, 28 Jan 2013 12:12:44 +0900
Cc: Julian Reschke <julian.reschke@gmx.de>, "Roy T. Fielding" <fielding@gbiv.com>, HTTP Working Group <ietf-http-wg@w3.org>
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Subject: Re: #428 Accept-Language ordering for identical qvalues
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-1 I don't think that's necessary; it already states that ordering is a good idea. 

On 28/01/2013, at 11:51 AM, "Martin J. Dürst" <duerst@it.aoyama.ac.jp> wrote:

> On 2013/01/25 22:55, Julian Reschke wrote:
>> On 2013-01-25 14:02, Julian Reschke wrote:
>>> On 2013-01-25 07:16, Julian Reschke wrote:
>>>> On 2013-01-25 06:31, "Martin J. Dürst" wrote:
> 
>>> This removes the new text about ordering, and adds the note below:
>>> 
>>> > Note: Some recipients treat language tags that have the same
>>> > quality values (including when they are missing) to be listed in
>>> > descending order of priority. However, this behavior cannot be
>>> > relied upon, and if their relative priority is important -- such
>>> > as for consistent results for a sequence of requests -- it ought
>>> > to be communicated by using different quality values.
>>> 
>>> Feedback appreciated, Julian
>> 
>> In the meantime, Roy resolved this in
>> <http://trac.tools.ietf.org/wg/httpbis/trac/changeset/2163>, which works
>> for me as well:
>> 
>> "Note that some recipients treat the order in which language tags are
>> listed as an indication of descending priority, particularly for tags
>> that are assigned equal quality values (no value is the same as q=1).
>> However, this behavior cannot be relied upon. For consistency and to
>> maximize interoperability, many user agents assign each language tag a
>> unique quality value while also listing them in order of decreasing
>> quality. Additional discussion of language priority lists can be found
>> in Section 2.3 of [RFC4647]."
> 
> Sorry, but I'm not yet happy with this. It doesn't mention the random return problem at all, and puts all responsibility on the client.
> 
> So I propose adding the following:
> 
> Note that it would be allowed for servers to return a version at random if they receive language tags with equal quality values. However, this can be very confusing for human users. A more deterministic behavior, e.g. treating the order in which language tags are listed as an indication of descending priority for tags that are assigned equal quality values, is preferable.
> 
> Regards,   Martin.

--
Mark Nottingham   http://www.mnot.net/