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Re: I-D Action:draft-reschke-rfc2231-in-http-00.txt

From: Julian Reschke <julian.reschke@gmx.de>
Date: Sat, 16 Aug 2008 10:08:11 +0200
Message-ID: <48A68AEB.2040009@gmx.de>
To: Frank Ellermann <hmdmhdfmhdjmzdtjmzdtzktdkztdjz@gmail.com>
CC: ietf-http-wg@w3.org, ietf-822@imc.org

Frank Ellermann wrote:
>> Filename        : draft-reschke-rfc2231-in-http-00.txt
> Good.  What's the plan wrt ABNF ?  This memo is harmless
> enough that it could offer both, a normative STD 68 ABNF,
> and an informative appendix using an appropriate mix of
> the 2231 + 2616 BNF.

My plan was to come up with test cases for the current support in user 
agents first. I want to make sure that the spec actually reflects what 
UAs support.

> As it happens the draft already contains an "appropriate
> mix", because it doesn't need the advanced feature of the
> #-rule.
> The general idea of "HTTP does not need continuations"
> could boil down to *WSP for all implicit LWS in the BNF.
> Or in other words replace any "=" by EQU, and specify
> | EQU = *WSP "=" *WSP
> Even if we end up with something slightly more obscure,
> e.g., EQU = [FWS] "=" [FWS], the BNF hides one subtle
> point in <ext-parameter>:
> | ext-parameter = attribute "*=" ext-value
> I _think_ that "*=" actually means "*" EQU in RFC 2231,
> i.e. there can be LWS between "*" and "=".

Yes, that is probably true. The question is: do we want that in the 
profile? I assumed that we want to reduce the number of places where WS 
is allowed.

> It can as well mean LWS "*" EQU, i.e. there can be LWS
> before "*", between "*" and "=", or after "=".
> I think it does _not_ mean LWS "*=" LWS remotely in the
> direction of an *= operator.

My hope was to make it exactly that, in order to make parsing simpler.

But yes, this is an open issue; I'll do some testing with 
Content-Disposition as implemented in practice. There's no point in 
putting it into the ABNF if we have evidence that those UAs that do 
support RFC2231 do not allow it (remember: the reason for a profile is 
to cut out the unnecessary stuff).

BR, Julian
Received on Saturday, 16 August 2008 08:08:56 UTC

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