[rfc-i] Re: ABNF (RFC2234) vs HTTP's augmented BNF syntax (RFC822 + RFC2616)

Dave Crocker dhc2 at dcrocker.net
Tue Feb 15 12:41:38 PST 2005


On Tue, 15 Feb 2005 10:39:58 -0500, Bruce Lilly wrote:
>  > The problem with 822's syntax isn't that it uses the implied LWS rule,
>
>  It's certainly not the only problem, and if all developers were
>  careful to observe the implications, it wouldn't be a practical
>  problem.  However, it has proven to be a problem in practice;
>  ignoring the issues with numeric components vs. month names for
>  the moment, whitespace around the colons in the time has been
>  an issue overlooked by some developers, leading to interoperability
>  problems (and colon is an RFC 822 "special", so there's no "atom"

There are different classes of "problem".  

Although RFC822 is rife with errors, limitations, and other sources of very legitimate frustration, most of the interoperability problems with Internet mmail stem from there being a serious lack of effort to conform to the standard.

It is not at all uncommon for a developer to have little or no familiarity with the formal specification of RFC822. (No, I'm not kidding.)  Rather, they observe the behavior of one or another existing implications and intuit the specification from that.

So, we need to be careful about detailed analyses, of the sort offered above, assuming that the problem is the document.

>From a meta-view, one of the strategic errors in RFC733/RFC822 was, I believe, allowing TOO MUCH variance in how things are formatted.  There were good reasons for making the choice to support multiple forms, but it turns out to have caused significant, long-term problems.


d/
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Dave Crocker
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