[core] YANG to CBOR mapping

[peter van der Stok <[e-mail]>]

Hi CoOL authors.

I have looked at your section 5, and see an enormous overlap with the 
CoMI section 6. Actually the two proposals are almost completely 
interoperable, with a few exceptions. Much of the CoMI proposal is based 
on the work of Ladislav Lhotka, described in 
draft-ietf-netmod-yang-json. CoMI refers to this draft and uses it 
extensively. In the CoOL draft the yang-json draft is ignored. That is a 
pity because you are redoing much of the work already done in the 
yang-json draft. In the CoMI draft we used the results of yang-json 
draft, exchanged the YANG name by the hash value, and passed it through 
the diagnostic JSON to CBOR translator. Quite a satisfactory and elegant 
solution.
Below, I have summarized my comparison between CoMI YANG to CBOR and 
CoOL YANG to CBOR. Please check for omissions and mistakes.
Differences concern Binary byte string and Bits. The CoMI choice of CBOR 
type is derived from yang-json, and I should like to hear the opinion of 
Ladislav on this aspect.
Other differences concern decimal64, and int; but I expect that is an 
oversight in the CoOL draft.
A major difference is the encoding of lists and list instances; I 
discuss that in a separate e_mail.
Given the overlap of work and the need for the expertise of the netmod 
WG, I recommend that a YANG CBOR draft is submitted to the netmod wg and 
uses as much as possible the contents of yang-json draft. Alternatively, 
I can imagine that CBOR mapping is added to the yang-json draft if the 
author, Ladislav Lhotka, and the WGs agree with that.

Greetings,

Peter
______________________________________________________________________________
Comparison of draft veillette-core cool, denoted with CoOL
With draft vanderstok-core-comi, denoted with CoMI
And draft ietf-netmod-yang-json, denoted with yang-json
Simple YANG type can be :
Binary byte string:                   CoMI, major type 2;                
          CoOL,  major type 0
Bits:                                 CoMI, array of text;               
          CoOL, major type 0
Boolean:                              CoMI, major type 7 (20,21);        
          CoOL, major type 7 (20,21)
decimal64:                            CoMI, major type 0 (pos) and 
1(neg);        CoOL major type 0
empty:                                CoMI major type 7(22);             
          CoOL major type 7(22)
enumeration:                          CoMI, major type 0;                
          CoOL major type 0
  identityref:                         CoMI, major type 3;                
           CoOL major type 3
  int8, int16, int32, int64:           CoMI, major type 0 (pos) and 
1(neg);         CoOL major type 0
  leafref:                             CoMI, follows leaf type;           
           CoOL follows leaf type
  string:                              CoMI, major type 3,                
           CoOL major type 3
  uint8, uint16, uint32, uint64:       CoMI, major type 0;                
           CoOL major type 0

In netmod-yang-json draft  JSON objects are used:
JSON object := { name: JSON object}, where name is a string. For CoMI 
and CoOL the name can be an integer which is valid for diagnostic JSON 
used for CBOR, giving:
CBOR object := {integer: CBOR object}

Leaf:
Yang-json,  Name : value, where name is the string identifier of the 
leaf, and value of Simple YANG type
CoMI: major type 5 containing: uint64, value;      CoOL: not defined

Union:
Yang-json,  use corresponding media type for type of value
CoMI, use corresponding CBOR type; CoOL, use corresponding CBOR type

anyxml,
YANG-json, value can be of any type.
CoMI, not applicable; CoOL, can be any CBOR type

Anydate,
Yang-json, follows container
CoMI, not applicable,                           CoOL, not applicable

container,
yang-json,	 name:  JSON object
CoMI: major type 5;                             CoOL, major type 5

leaf-list
yang-json, name: [ value 1, value 2,……]
CoMI, major type 4,                             CoOL, major type 4

List
Yang-json, name:[ JSON object1, JSON object2, ….]
CoMI, major type 5 of major type 5,             CoOL, major type 4 of 
major type 5



-- 
Peter van der Stok
vanderstok consultancy
mailto: [e-mail]