Re: [Cbor] Reviews and shepherd for draft-ietf-cbor-cddl-more-control

["lgl island-resort.com" <[e-mail]>]

This is in reference to this text in the draft.

In general, this control operator is hard to validate as it would require full parser functionality. It is therefore recommended to only use it in simple cases, and leave full parsing to ABNF (see Section 3 of [RFC9165]) or similar.

On Apr 11, 2024, at 6:27 AM, Carsten Bormann <[e-mail]> wrote:

Plaining to try out .join to validate the JWT message, a series of b64 strings separated by “.”.

Successfully got that to work, but only after Carsten said to add an extra layer of (). I suspect the example in the document won’t work without the extra () either.


So far not sure what to make of the comment about complex use of .join and switching to ABNF.  Seems more like tool documentation than a standards.

I think it is useful to mention that it is not easy to do a full implementation of this.

Maybe this instead:

This control operator is hard to fully implement. Some cddl tools may only partially implement it or not implement it at all. Authors of CDDL documents using this should check to see if the cddl tools they plan to use support it.

Personally, I don’t know what “simple cases” are here, so I don’t find that text useful. Seems like most of us using CDDL to author documents won’t know what simple is either.

It’s hard for a document author specifying with CDDL to know if they should use .join or not. If one is planning on broad and general use of some CDDL for validation, probably not at this point. On the other hand it is powerful and useful.

Note that I’m thinking of draft-ietf-cbor-cddl-more-control and friends as instructions to IETF document authors as well as a standards-track specification for implementors of CDDL tools.

LL