Subject: [Cbor] draft-ietf-cbor-cddl-01: approaching WGLC?

From: Carsten Bormann <[email-masked]>
Date: Sun, 28 Jan 2018 09:04:38 +0100

We just submitted draft-ietf-cbor-cddl-01:

Htmlized:       https://tools.ietf.org/html/draft-ietf-cbor-cddl-01
Diff:           https://tools.ietf.org/rfcdiff?url2=draft-ietf-cbor-cddl-01.txt

draft-ietf-cbor-cddl-01 addresses the following issues:

* Creation of (and pointing to) a freezer document with all the things
  that would be nice to have but won't make it into the initial RFC
  (https://tools.ietf.org/html/draft-bormann-cbor-cddl-freezer-00)

* Creation of Appendix C for a concise definition of the matching
  rules (and ABNF became Appendix B) [as seen here before]

* Using XSD2 regexps instead of PCRE (possibly breaking change for
  those specifiations that use regexps!) [as seen here before]

* Add a minimal "cut" proposal to solve the requirement identified in
  the "Validation of maps" thread.  (There might be some minimal
  breakage here in a small number of specifications, too!)

* Get rid of some cobwebs (e.g., Appendix A has been dissolved into
  the pertinent subject sections).

* Many other editorial fixes (e.g., we have reordered 2.1 a bit,
  making the weird example less prominent); some RFC 7322 style guide
  fixes.

Not yet addressed:

* Issue #4 (ABNF for hex floats); unless someone has some ABNF handy
  we could steal, we'll need some more quality time with tools to
  create a validated patch for this.

* A few editorial comments in the document itself (some of which
  probably now can just be ticked off as wontfix).

Apart from that issue #4, this should empty the list of "must have"
technical changes.  (The WG may of course be of a different opinion...)

It also makes it a good time to send in editorial comments (on github
or directly to the authors!) if you want them fixed before WGLC.

The plan is to have the -02 with those final changes out within the
next four weeks so we still have time to finish the WGLC before
London.

Grüße, Carsten

---

From: Carsten Bormann <[email-masked]>
Date: Tue, 30 Jan 2018 13:01:24 +0100

>  create a validated patch for this.

Looking at C99 (ISO 9899), plus some simplifying, yields:

hexfloat = "0x" (*HEXDIG "." 1*HEXDIG) / (1*HEXDIG ["."]) "p" exponent

C99 allows 0x.fp0 or 0xf.p0, which is a bit out of character for the
rest of CDDL (which does not allow .3 or 3.); so I'd further simplify
this to:

hexfloat = "0x" 1*HEXDIG ["." 1*HEXDIG] "p" exponent

Note that this allows fewer ways of writing hexfloats than C99, but
all of them would retain their C99 semantics (which we would then
simply reference).

I notice that the current production for exponent (which are decimal
even in C99 hexfloats) is a bit too liberal at the moment, allowing
for 1.1e0b00111000 :-), but not 0.3e+05, so maybe we should also
turn that into a more specific:

exponent = ["+"/"-"] 1*DIGIT

Grüße, Carsten

---

From: Brian E Carpenter <[email-masked]>
Date: Wed, 31 Jan 2018 16:18:41 +1300

> We just submitted draft-ietf-cbor-cddl-01:

I've looked through the changes and think this is in good shape
(ignoring the hex float issue, where I have no opinion). So
going for a WGLC before the IETF meeting sounds like a good plan.

Regards
   Brian