Re: [NGO] Re: Why NETCONF needs a data modeling language

Juergen Schoenwaelder píše v Čt 29. 11. 2007 v 16:30 +0100:
> > 
> > For example, NETCONF data could be validated (as an XML document) using
> > the existing tools, RNG specification requires that foreign elements be
> > ignored. As for the subset of RNG - could it perhaps be just a
> > convention, like "avoid mixed content"?
> 
> This is what was done with ASN.1 in the early 1990s to form the
> SMI. To scale and to interoperate, we then needed tools that can check
> such "conventions" (or "constraints") on the underlying language.

But this freedom is only given to schema authors and not to its users
who create the XML document instances. If a data model were to become an
Internet Standard, it would have to follow the conventions.

> Transformations YANG->RNG (or YANG->XSD) actually guarantee
> consistency since such translations makes it clear that YANG is the
> binding specification. You get real nasty consistency problems if

The single authoritative specification can be protected e.g., by means
of MD5 hash but it's not so easy for the translation output that will be
produced repeatedly, perhaps by different programs.

> > For the extension within an IETF-controlled namespace this could be
> > guaranteed, but of course if the XML world turns entirely to Yet
> Another
> > Schema Language, the extension would have to be ported to it. Given
> the
> > momentum behind RNG these days, I don't think it is very likely.
> 
> This is what ASN.1 people believed in the late 80s as well... I assume
> Google is archiving all this somewhere and so we can meet in 2027
> again and revisit the situation. ;-)

Well, ASN.1 has been used by a handful of people compared to XML.

> 
> Anyway, I think we are at a point where I understand your position and
> you understand mine. I assume it is unlikely that we convince each
> other to change our position; so unless there are new arguments, we
> should probably just let this thread stand where it is.

I agree, and I am not against YANG, the problem we face is that
practical experience with both approaches is minimal so it's hard to
make a qualified decision.

Lada

-- 
Ladislav Lhotka, CESNET
PGP Key ID: E74E8C0C

_______________________________________________
NGO mailing list
NGO@ietf.org
https://www1.ietf.org/mailman/listinfo/ngo