Subject: Re: Moving ABNF to Draft Status

From: [email-masked] (Claus André Färber)
Date: 15 Sep 1998 12:09:00 +0200

Chris Newman <[email-masked]> schrieb [quite long ago, but I  
think the issue is worth being opened again]:
> On Tue, 2 Jun 1998, Jacob Palme wrote:
> > I understand that the HTTP working group decided not to use ABNF,
> > because it was not suitable to their needs. Which alternative
> > version of ABNF are they using? Are they using the old RFC822
> > version, or have they defined their own ABNF? Why is ABNF not
> > suitable for them? Can we, before moving ABNF to draft, investigate
> > whether it is possible to modify ABNF so that it suits also their
> > needs?
>
> There were four specific reasons I was given for why HTTP didn't use ABNF:
>
> (1) Lack of the # construct.
> (2) Lack of a way to express implied whitespace between tokens.
> (3) Use of "/" instead of "|" for alternates when HTTP uses "/" heavily.
> (4) Not worth the trouble to redo all the BNF.

There's nothing you can do about laziness. There were reasons to remove  
(1) and (2) and they only require to slightly change the BNF as do (3)  
and (4). Actually, (1) depends on (2), which was removed/changed for a  
good reason.

The most important requirement that the HTTP wg has on ABNF is to become  
a Draft Standard quickly.

BTW, isn't ABNF more a candidate for BCP than for the Standards Track?

--
Claus Andre Faerber <http://www.muc.de/~cfaerber/> Fax: +49_8061_3361
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---

From: Dave Crocker <[email-masked]>
Date: Tue, 15 Sep 1998 16:00:26 +0100

>(1) and (2) and they only require to slightly change the BNF as do (3)  

The fact that HTTP, the protocol, uses "/" as a separation character has
only marginal impact on the fact that the definition language (BNF, ABNF,
or whatever) also uses it.  

One might, as easily, note that they eye perceives "/" more easily than "|"
and, for that matter, that "|" can be mistaken for "1" in many fonts.  In
other words, #3 is difficult to use as a serious argument.  As to #1 and #2
(there's a small pun in my notation, sorry):  those watching Drums will
recall that dropping these points from ABNF was subject to quite a bit of
debate.  One can, of course, claim not to accept the results of that
debate.  That is why "standards" from the IETF have no enforcement teeth.
However, one can also choose to take note of the effort that went into
making the decision to drop them and, just possibly, treat the work as
valuable.

>and (4). Actually, (1) depends on (2), which was removed/changed for a  

#4 is an extremely powerful argument.  "Effort" always matters, especially
if benefit is perceived as being marginal, at best.

>BTW, isn't ABNF more a candidate for BCP than for the Standards Track?

ouch.  that's another subject of much debate.  I hope you can live without
pursuing it again.

d/

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