Re: Andy Newton's Discuss on draft-ietf-httpbis-cache-groups-05: (with DISCUSS)

Hi Andy,

> On 1 May 2025, at 6:52 am, Andy Newton via Datatracker <noreply@ietf.org> wrote:
> 
> Thanks for writing this document. It is very well written and easy to read.
> 
> ### Your Fav Pop Star HERE
> 
> I hate to be that guy, but...
> 
> 187        Cache-Group-Invalidation: "eurovision-results", "kylie-minogue"
> 
> TIL that Australia is a member of the EBU and therefore this is a logical
> grouping, however does this document require the use of real people and
> organizations to create an interoperable specification?

Require? No. However, realistic examples are more illustrative and useful to readers.

> ### Maximum Length
> 
> I see that minimum lengths are set:
> 
> 205        Implementations MUST support at least 32 groups in a field value,
> 206        with up to at least 32 characters in each member.  Note that generic
> 207        limitations on HTTP field lengths may constrain the size of this
> 208        field value in practice.
> 
> However, no maximum field or string lengths are set. I see this in RFC 9651:
> 
>    This specification defines minimums for the length or number of
>    various structures supported by implementations. It does not specify
>    maximum sizes in most cases, but authors should be aware that HTTP
>    implementations do impose various limits on the size of individual
>    fields, the total number of fields, and/or the size of the entire
>    header or trailer section.
> 
> Should this document set maximums? If not, is the expected behavior that the
> headers are ignored?

Adding yet another maximum to those that are implementation-defined would make interop even more difficult -- especially since some would read that as "these sizes are supported" even though other maximums would interfere. 

Current practice in HTTP is what we've done -- define a floor so that people can depend on a certain level of support, but leave the top end open so that we don't foreclose use cases that require large values. See eg Structured Fields, URL sizes.

Cheers,

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

Received on Thursday, 1 May 2025 00:21:51 UTC