Re: [core] map (5), ordering vs YANG SID in ietf-core-yang-cbor

Carsten,

if I search for 'delta' or 'reference SID', I do not find text that
says what the reference SID is. Where do I have to look at to
understand that delta SIDs are parent-referenced?

/js

PS: Why do we have this, I mean, why is there a $ for some of these?

           pattern 'Module|Submodule|feature|' +
	           'identity$|node$|notification$|rpc$|action$';

    Why is this not an enum in the first place? And why are the
    first two capitalized?

PS: Why do you not import yang-identifier from ietf-yang-types?

On Thu, Aug 17, 2017 at 07:48:20AM +0200, Carsten Bormann wrote:
> Hi Michael,
> 
> SID deltas in maps are parent-referenced (and not sibling-referenced) for this reason.
> Do you see anything that makes you think they are sibling-referenced?
> That would indeed not work in maps.
> 
> (We discussed using one or more of your solutions for introducing “ordered maps”, but then it seemed parent-referenced was good enough.)
> 
> Grüße, Carsten
> 
> 
> > On Aug 17, 2017, at 05:03, Michael Richardson <mcr+ietf@sandelman.ca> wrote:
> > 
> > 
> > Hi. I was trying to generate some code to implement a YANG model in
> > CBOR using:
> >  https://tools.ietf.org/html/draft-ietf-core-yang-cbor-05#section-4.2
> > 
> > which quite clearly says that I'm to use a CBOR map type (5).  Except that
> > my understanding of SIDs is that they are deltas for the key part.
> > (My other problem is that I don't have a SID until the SID document
> > progresses, but I can use the experimental range for now)
> > 
> > In many languages for which there are easy to use CBOR bindings, ruby,
> > python, perl, js, java, the CBOR map translates to a hash or directionary.
> > So I wondered how I could do deltas on keys in such an unordered structure...
> > 
> > My reading of:
> >  https://tools.ietf.org/html/draft-ietf-core-yang-cbor-05#section-4.2
> > about type 5, and then I read:
> >  https://tools.ietf.org/html/rfc7049#section-3.7
> > 
> > which says:
> >   The CBOR data model for maps does not allow ascribing semantics to
> >   the order of the key/value pairs in the map representation.
> > 
> > so, it seems that the SID concept as described in ietf-core-yang-cbor can not
> > work using the map type!!!
> > At first I thought it was just a language binding issue; that I needed
> > ordered sets of some kind, but no... It violates the above property.
> > 
> > Solutions that I can imagine:
> > 1) use an array of 2-element arrays (requires an extra byte for each inner
> >   array!)
> > 2) use an array 2x the size, and let the application reconstruct things as a
> >   hash after taking in account the SID delta.
> > 3) use one of the discussed point/multi-dimensional-array/etc. structures
> >   that I believe were presented at IETF99... I think draft-jroatch-cbor-tags
> >   was the document.
> > 
> > I think that I favour (2), as being the most expedient and easiest to implement.
> > 
> > --
> > Michael Richardson <mcr+IETF@sandelman.ca>, Sandelman Software Works
> > -= IPv6 IoT consulting =-
> > 
> > 
> > 
> > _______________________________________________
> > core mailing list
> > core@ietf.org
> > https://www.ietf.org/mailman/listinfo/core
> 
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-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
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