[rfc-i] Excursion on RFC 5444 [Was:Re: Jave ascii art editor]

Riccardo Bernardini framefritti at gmail.com
Wed Jun 25 02:36:53 PDT 2014


On Wed, Jun 25, 2014 at 11:14 AM, Dearlove, Christopher (UK)
<chris.dearlove at baesystems.com> wrote:
> One could have a valid discussion on which formalisation to use. ABNF may be official, but really not many people are familiar with it. Regexp is familiar to I believe many more people, but its normal purpose is not as a specification.
>

It should be said, however, that ABNF is more powerful of Regexp (at
least in its original form that describes regular languages; I agree
that there are some extensions that increase the power of Regexp).
Moreover, I find most ABNFs quite more readable than a Regexp of mild
complexity.

> But a formalisation of format is good. I recently tripped up (temporarily) misinterpreting a picture-based definition in an older RFC (less than half of current numbering) - I misinterpreted which unit was to be repeated when given an ellipsis block. A formal specification would have helped.

+1 from me about the need of a formal description.  Actually, in some
cases I use both: the graphical representation is more intuitive and
easier to understand by a human being, the formal description is
(should be) more unambiguous and precise.  Just make clear that the
picture is only informative, while the ABNF (or other formal
description) is normative.  In case of mismatch the normative
description wins.

>
> (The biggest block - not Elwyn - to 5444 was at least one person who didn't believe that a format should be specified independently of a protocol. Another issue.)
>
> --
> Christopher Dearlove
> Senior Principal Engineer, Communications Group
> Communications, Networks and Image Analysis Capability
> BAE Systems Advanced Technology Centre
> West Hanningfield Road, Great Baddow, Chelmsford, CM2 8HN, UK
> Tel: +44 1245 242194 |  Fax: +44 1245 242124
> chris.dearlove at baesystems.com | http://www.baesystems.com
>
> BAE Systems (Operations) Limited
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>
>
> -----Original Message-----
> From: rfc-interest [mailto:rfc-interest-bounces at rfc-editor.org] On Behalf Of Elwyn Davies
> Sent: 24 June 2014 23:44
> To: Thomas Clausen
> Cc: rfc-interest at rfc-editor.org
> Subject: [rfc-i] Excursion on RFC 5444 [Was:Re: Jave ascii art editor]
>
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>
> [Totally off topic]
>> For the format defined in RFC5444 (a regexp derivative - and here’s a
>> memory test, Elwyn, who was the GEN-ART reviewer for that document?)
>
> Had to retrieve that one from tertiary storage! :-)
>
> January 2008 was a while and about 80 gen-art reviews ago! ARRGH!!!
> Quite a contentious one that.  RegExp raised a few hackles (I was quite mild on that one I thought).
>
>
>>  and used in a few protocols now,
>
> Perhaps we should try out RFC 5444 for the DTN BPbis (coming to an incipient DTN WG maybe after Toronto).
>
> I have to say that there are aspects of the existing RFC 5050 BP that might be better expressed as ABNF (or a RegExp grammar).
>
> /elwyn
>
>
>
>
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