Subject: Re: [Rtg-yang-coord] [netmod] Recursive modeling in Yang?

From: Randy Presuhn <[email-masked]>
Date: Fri, 12 Dec 2014 10:03:32 -0800 (GMT-08:00)

Hi -

>From: Kent Watsen <[email-masked]>
>Sent: Dec 12, 2014 7:43 AM
>To: Ladislav Lhotka <[email-masked]>, Jeffrey Haas <[email-masked]>
>Cc: "[email-masked]" <[email-masked]>, "[email-masked]" <[email-masked]>
>Subject: Re: [netmod] [Rtg-yang-coord] Recursive modeling in Yang?
>
>
>
>>Yes, this has already been discussed several times. It was a deliberate
>>design decision to avoid recursive structures in YANG.
>
>
>As I understand it, the decision was made was to enable parsers to be
>deterministic.  Is that right?  - how is it then that other MLs (XSD) can
>support recursion?

Ancient history note:  in the CMIP / GDMO world object containment
recursion was featured from the very outset.  It caused no controversy.
It did not complicate implementation of industrial-strength modeling
language processors, protocol engines, agents, subagents, or managers.
I'm not aware of it having caused any deployment troubles.  With all
classes being subclasses of "top", one can sensisbly argue that all
containment in the CMIP world is effectively recursive. Subclass-specific
containment rules ("name bindings" in that alternative universe) come for
free as soon as one accepts the requirement to support extensibility
without requiring reinitialization of the management infrastructure.

The decision to separate name bindings (containment constraints)
from class definitions was crucial, given the versioning rules
and ability to define subclasses in that environment.

Randy

---

From: Phil Shafer <[email-masked]>
Date: Mon, 15 Dec 2014 22:59:05 -0500

>recursion was featured from the very outset.  It caused no controversy.

NETCONF rejected the idea of "objects".  Config data is just data,
nothing more magical.

>language processors, protocol engines, agents, subagents, or managers.

Saying that CMIP and GDMO were not complicated is, well, odd.  Even
the small port of the ocean that NETCONF boils turns out to be
fairly complicated.

Thanks,
 Phil