Re: #428 Accept-Language ordering for identical qvalues

Julian Reschke <julian.reschke@gmx.de> Fri, 18 January 2013 11:11 UTC

Return-Path: <ietf-http-wg-request@listhub.w3.org>
X-Original-To: ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com
Delivered-To: ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 037DA21F8862 for <ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com>; Fri, 18 Jan 2013 03:11:16 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -9.234
X-Spam-Level:
X-Spam-Status: No, score=-9.234 tagged_above=-999 required=5 tests=[AWL=1.365, BAYES_00=-2.599, RCVD_IN_DNSWL_HI=-8]
Received: from mail.ietf.org ([64.170.98.30]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id 8qrUZvmrtniK for <ietfarch-httpbisa-archive-bis2Juki@ietfa.amsl.com>; Fri, 18 Jan 2013 03:11:15 -0800 (PST)
Received: from frink.w3.org (frink.w3.org [128.30.52.56]) by ietfa.amsl.com (Postfix) with ESMTP id 3F58E21F8900 for <httpbisa-archive-bis2Juki@lists.ietf.org>; Fri, 18 Jan 2013 03:11:15 -0800 (PST)
Received: from lists by frink.w3.org with local (Exim 4.72) (envelope-from <ietf-http-wg-request@listhub.w3.org>) id 1Tw9qA-0005IW-AQ for ietf-http-wg-dist@listhub.w3.org; Fri, 18 Jan 2013 11:10:30 +0000
Resent-Date: Fri, 18 Jan 2013 11:10:30 +0000
Resent-Message-Id: <E1Tw9qA-0005IW-AQ@frink.w3.org>
Received: from lisa.w3.org ([128.30.52.41]) by frink.w3.org with esmtp (Exim 4.72) (envelope-from <julian.reschke@gmx.de>) id 1Tw9q6-0005HV-Tq for ietf-http-wg@listhub.w3.org; Fri, 18 Jan 2013 11:10:26 +0000
Received: from mout.gmx.net ([212.227.17.21]) by lisa.w3.org with esmtp (Exim 4.72) (envelope-from <julian.reschke@gmx.de>) id 1Tw9q6-0003hg-1S for ietf-http-wg@w3.org; Fri, 18 Jan 2013 11:10:26 +0000
Received: from mailout-de.gmx.net ([10.1.76.31]) by mrigmx.server.lan (mrigmx002) with ESMTP (Nemesis) id 0MbvL6-1TgH8w0MrO-00JJVd for <ietf-http-wg@w3.org>; Fri, 18 Jan 2013 12:10:00 +0100
Received: (qmail invoked by alias); 18 Jan 2013 11:09:59 -0000
Received: from mail.greenbytes.de (EHLO [192.168.1.102]) [217.91.35.233] by mail.gmx.net (mp031) with SMTP; 18 Jan 2013 12:09:59 +0100
X-Authenticated: #1915285
X-Provags-ID: V01U2FsdGVkX1+LgxM2UnyLn+L3+CKEF0egbIU3Y6isoeSlmOfsrm 2G0D6EFABQj6BO
Message-ID: <50F92D87.8050905@gmx.de>
Date: Fri, 18 Jan 2013 12:09:59 +0100
From: Julian Reschke <julian.reschke@gmx.de>
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:17.0) Gecko/20130107 Thunderbird/17.0.2
MIME-Version: 1.0
To: Amos Jeffries <squid3@treenet.co.nz>
CC: ietf-http-wg@w3.org
References: <50F6CD98.8080802@gmx.de> <2BF19800-66E0-42DC-B0B5-0F8CA6AE6379@gbiv.com> <50F7C0DC.90906@gmx.de> <838B1C13-3170-4BA1-8F1F-E171137E0BC8@gbiv.com> <50F86739.40302@gmx.de> <50F90BEF.8080604@treenet.co.nz> <50F910C8.5010200@gmx.de> <50F92B19.3030408@treenet.co.nz>
In-Reply-To: <50F92B19.3030408@treenet.co.nz>
Content-Type: text/plain; charset="ISO-8859-1"; format="flowed"
Content-Transfer-Encoding: 7bit
X-Y-GMX-Trusted: 0
Received-SPF: pass client-ip=212.227.17.21; envelope-from=julian.reschke@gmx.de; helo=mout.gmx.net
X-W3C-Hub-Spam-Status: No, score=-3.3
X-W3C-Hub-Spam-Report: AWL=-3.261, FREEMAIL_FROM=0.001, RCVD_IN_DNSWL_NONE=-0.0001, SPF_PASS=-0.001
X-W3C-Scan-Sig: lisa.w3.org 1Tw9q6-0003hg-1S 501282e06112dc7e8d216b6663d4e476
X-Original-To: ietf-http-wg@w3.org
Subject: Re: #428 Accept-Language ordering for identical qvalues
Archived-At: <http://www.w3.org/mid/50F92D87.8050905@gmx.de>
Resent-From: ietf-http-wg@w3.org
X-Mailing-List: <ietf-http-wg@w3.org> archive/latest/15997
X-Loop: ietf-http-wg@w3.org
Resent-Sender: ietf-http-wg-request@w3.org
Precedence: list
List-Id: <ietf-http-wg.w3.org>
List-Help: <http://www.w3.org/Mail/>
List-Post: <mailto:ietf-http-wg@w3.org>
List-Unsubscribe: <mailto:ietf-http-wg-request@w3.org?subject=unsubscribe>

On 2013-01-18 11:59, Amos Jeffries wrote:
> On 18/01/2013 10:07 p.m., Julian Reschke wrote:
>> On 2013-01-18 09:46, Amos Jeffries wrote:
>>> ...
>>> ...
>>> I'm with Roy on this one. It's not adding any new requirement about
>>> interpretation, simply stating that the list is ordered, as is actually
>>> the case from most senders.
>>> There is no requirement added/removed about server interpretation so
>>> those servers implementing random selection out of the ordered set are
>>> still compliant. Those servers implementing ordered interpretation are
>> > ...
>>
>> They are? How so?
>>
>> If the client sends
>>
>>     Accept-Language: en, de
>>
>> and the server returns German text, although English would have been
>> available, is it still compliant?
>
> Where is the text saying the server MUST or even SHOULD return the
> clients first preference?
> I could not find any in RFC 2068, 2616 or the current Draft.

How is it relevant whether there's a SHOULD or MUST?

If the specification describes the meaning of the message, and the 
server ignores some part of that, it's not working per spec.

> The server gets to decide what it returns, the text is lacking in
> normative requirements, so we are quibbling over
> compliance/non-compliance with textual guidance on best interoperable
> practice.

The text describes the semantics of the header field. It doesn't need to 
invoke MUSTs or SHOULDs for that.

>>> now compliant - where before with the list defined as un-ordered they
>>> would be non-compliant due to mis-interpreting an un-ordered list as
>>> ordered.
>>
>> That doesn't make sense, sorry.
>>
>> If the list ordering is defined to be irrelevant it's totally ok to
>> pick the first match.
>>
>
> If the ordering is defined as relevant to the clients preference, why is
> it non-compliant to pick one of the *available* ones randomly? a bit
> daft, but as you say that used to be prescribed so tose who opted to
> follow the old text see no harm in it. They have the option of
> optimizing a bit or ignoring the new text.

If the client says "I take A and B but prefer A", and the server has 
both, then returning B is not the right thing to do.

>>> ...
>>>> Right now they interoperate as specified by the spec. If we change the
>>>> spec, they do not anymore (or only some of the time).
>>>>
>>>
>>> The new spec does not forbid random selection. Merely states that the
>>> client *wants* it to be interpreted non-randomly. Obeying that client
>>> preference is still optional.
>>> ...
>>
>> Again, that doesn't make any sense at all.
>>
>> If we say that the list is ordered by preference (in absence of
>> qvalues), this implies that a recipient should pick the *first*
>> matching language. If it does not, it's not interpreting the message
>> as defined.
>
> Sure it is both unfriendly to the client and requires sub-optimal code
> to actually perform. But there is still no requirement to return the
> *first* matching language after the change. Just the implication that
> more optimal code may be used.

We seem to have a fundamental disagreement about the way the spec 
defines things. This is not the only place where we define things by 
simply stating facts; it doesn't mean a server can simply ignore those 
things and still be considered doing the right thing.

Best regards, Julian