> In my view, if it is a bug, it is in the design of the union type in YANG - 
> there is no general way to signal the actual union member type for an 
> instance.

Right.  The ambiguity is normally not a problem for a type choice (which is 
just a union of the possible values of all types given), unless what specific 
alternative was chosen is intended to carry semantics.

> I believe it is a good thing that some encodings allow for at least partial 
> signalling.
> 
> Note that similar issues may arise even more often in CBOR, see e.g. comments 
> for section 5.12 in
> 
> https://mailarchive.ietf.org/arch/msg/core/Zrb2yhSSdlouS6PI9qfsA1bsDB4/

In the original YANG (XML-only), everything was represented as a text string, 
so the ambiguity was the highest we see now.  YANG-JSON and YANG-CBOR provide 
progressively more disambiguating information, so the interpretation (which 
chosen alternative) may be different from the one after converting to YANG-XML.

It gets slightly worse if the non-text type has a conversion to text that is 
not fully nailed down; I don’t know if that is a problem with the current set 
of YANG types, but any new type could of course worsen the situation.

The onus is now on the author of the YANG module to make sure that the varying 
levels of ambiguity do not cause a problem.  I would be interested to know 
whether there is any tool support for this.

Grüße, Carsten

_______________________________________________
netmod mailing list
[email protected]
https://www.ietf.org/mailman/listinfo/netmod

Reply via email to