Re: empty lists?, was: Last Call: <draft-ietf-httpbis-header-structure-18.txt> (Structured Field Values for HTTP) to Proposed Standard

> On 19 May 2020, at 7:23 am, Benjamin Kaduk <bkaduk@akamai.com> wrote:
> 
>>> You saw
>>> 
>>>    An empty List is denoted by not serializing the field at all.
>>> 
>>> right?
>> 
>> That's about serialization.
>> 
>> 4.2.1 seems to parse an empty string into an empty list.
>> 
>> AFAICT, that's in conflict with the ABNF.
> 
> Thanks for clarifying.

As per S 1.2 [1], the ABNF is not for parsing; it's for 'illustrat[ing] the range of acceptable wire representations.'

The ABNF requires at least one member because sending an empty field value is not good practice; it's not something we encourage.


> FWIW I already have a comment staged about how we seem to make the
> ABNF normative for serialization but the prose normative for parsing,
> which seems like a weird mismatch that requires justification.

ABNF isn't normative for serialisation; what led you to that conclusion? 



1. https://httpwg.org/http-extensions/draft-ietf-httpbis-header-structure.html#notational-conventions

--
Mark Nottingham   https://www.mnot.net/

Received on Monday, 18 May 2020 23:21:29 UTC