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Re: #307 (untangle Cache-Control ABNF)

From: Julian Reschke <julian.reschke@gmx.de>
Date: Mon, 11 Jun 2012 15:16:24 +0200
Message-ID: <4FD5EFA8.4030007@gmx.de>
To: Mark Nottingham <mnot@mnot.net>
CC: HTTP Working Group <ietf-http-wg@w3.org>
On 2012-06-11 15:02, Mark Nottingham wrote:
>
> On 11/06/2012, at 10:51 PM, Julian Reschke wrote:
>
>> On 2012-06-11 14:44, Mark Nottingham wrote:
>>> Assuming that the text isn't changing in substance, yes.
>>>
>>> I think this is verging on editorial; if anyone has concerns about this direction, please speak up; otherwise, Julian go ahead.
>>> ...
>>
>> It's a bit more than editorial, because it tries to address the mismatch between the ABNFs for predefined directives (special-cased), and extension directives (token *and* quoted-string).
>
> Ah.
>
>>
>> Highlighting these changes:
>>
>>   Cache directives are identified by a token, to be compared case-
>>   insensitively, and have an optional argument, that can use both token
>>   and quoted-string syntax.  Recipients MUST accept both forms.
>
> The MUST is going too far here. I think that individual parameters can (and do) constrain the syntax.

Well, they should not. It's pointless. Do you expect a parser for 
cache-control to special-case every constraint it knows about? What 
happens with an extension header that has constrained syntax? Some 
parsers will apply the constraint, some won't.

It's the same discussion we've had for other fields (say 
WWW-Authenticate, Expect, Prefer, STS, ...); and the answer should be 
the same.

We can't change what's out there, but we need to provide guidance how to 
fix these parsers to make them reliable.

Best regards, Julian
Received on Monday, 11 June 2012 13:17:00 GMT

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