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Re: #168: understanding CC directives

From: Adrien de Croy <adrien@qbik.com>
Date: Tue, 08 Jun 2010 00:24:45 +1200
Message-ID: <4C0CE50D.2060807@qbik.com>
To: Mark Nottingham <mnot@mnot.net>
CC: Julian Reschke <julian.reschke@gmx.de>, HTTP Working Group <ietf-http-wg@w3.org>, Jamie Lokier <jamie@shareable.org>


On 3/06/2010 7:06 p.m., Mark Nottingham wrote:
> On 02/06/2010, at 6:45 PM, Julian Reschke wrote:
>    
> Furthermore, the BNF doesn't make it clear that request and response 
> directives shouldn't be intermixed;
>>>     Cache-Control-v = 1#cache-directive
>>>
>>>     cache-directive = cache-request-directive
>>>
>>>         / cache-response-directive
>>>        
>> That could be addressed by saying:
>>
>>      Cache-Control-v = 1#cache-request-directive
>>                      / 1#cache-response-directive
>>
>> However, I'm not sure we need to express this as a syntactical constraint (and it also might confuse people with respect to whether this header uses the "list style" or not).
>>      
>
> Yes; I'm not sure we can really do anything about this, except make sure it's clear in the prose.
>
>    

hang on a minute.  The existing BNF is logically incorrect, the proposed 
replacement is logically correct, but we worry about confusion?

I think it's more likely to create implementor confusion by having the 
ABNF disagree with the prose.  It should still be clear to anyone that 
the choice is between a list of request directives or a list of response 
directives.

Maybe the problem is that in fact the Cache-control request header is 
different to the Cache-control response header.  You shouldn't put the 
Cache-control request header in a response message and vice-versa.

Probably going to far to solve that one though, since it would require 
something like

Cache-control-v = Cache-control-req / Cache-control-resp
Cache-control-req = 1#cache-request-directive
Cache-control-resp = 1#cache-response-directive

Regards
Adrien

> Cheers,
>
>
> --
> Mark Nottingham     http://www.mnot.net/
>
>
>    

-- 
Adrien de Croy - WinGate Proxy Server - http://www.wingate.com
Received on Monday, 7 June 2010 12:26:02 GMT

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