Re: [netmod] Does the YANG "status" statement inherit from its parent node?

On Wed, Dec 21, 2016 at 11:49 PM, Ladislav Lhotka <lhotka@nic.cz> wrote:

>
> > On 22 Dec 2016, at 07:22, Randy Presuhn <randy_presuhn@alumni.
> stanford.edu> wrote:
> >
> > Hi -
> >
> > On 12/21/2016 3:55 PM, Andy Bierman wrote:
> >>
> >>
> >> On Wed, Dec 21, 2016 at 3:41 PM, Juergen Schoenwaelder
> >> <j.schoenwaelder@jacobs-university.de
> >> <mailto:j.schoenwaelder@jacobs-university.de>> wrote:
> > ...
> >>    Perhaps I am blinded by the way @deprecate or __attribute__
> >>    ((deprecated)) or [[deprecated]] work in various programming
> >>    languages. All these annotations do not deprecate my code, they just
> >>    cause the generation of warnings so that I get aware of the issue and
> >>    can do my homework.
> >>
> >>
> >> There are no protocols that let you manage orphaned data nodes
> >> without any parent.  No way to represent it in XML or JSON either.
> >> No way to specify a RESTCONF target resource that leaves out
> >> some intermediate data nodes.
> >
> > Deprecating (or obsoleting) a definition does not orphan data nodes.
> > Perhaps I'm blinded by the way SNMP works, but it seems to me that
> > a robust client will need to be able to process data corresponding
> > to deprecated (or obsolete) definitions.  Likewise, developers
> > of server-side software may find themselves in situations where
> > supporting obsolete definitions is a commercial necessity.  Things
> > certainly played out that way in the SNMP world.  I agree with Juergen
> > that tool-generated warnings seem to be the correct way to go.
>
> I agree that making a node deprecated or obsolete doesn't mean that its
> descendants are orphaned, it just means they cannot be current, and then
> "current" shouldn't be the default status for them - also because the
> descendants may come from other modules (via groupings and augments) that
> cannot be changed.
>
> Even if the default status is inherited, tools can still generate
> warnings. A data modeller can decide whether and where it makes sense to
> have the "status" statement explicitly, but isn't forced to do it
> everywhere.
>
>

NETCONF and RESTCONF have no mechanisms for accessing data other than
top-down from the top-level YANG data node to the target node.
Removing an ancestor node from the server implementation effectively removes
the entire subtree from the implementation.  (The value of the YANG
status-stmt
of the descendant nodes has nothing to do with it)

> Lada
>

Andy

>
> >
> >> It seems obvious that the deprecated warning (this node may go away)
> >> also applies to all descendant nodes.  Once the node is changed from
> >> deprecated to obsolete, all the descendant nodes are gone as well,
> >
> > No, they're not *gone*.  The *advisability* of implementing them has
> > changed, but the definitions still exist, and implementer judgement
> > is still needed.  The change in status only means that a client is
> > less able to rely on the assumption that those definitions will be
> > supported by a given system - but there's very little that it can
> > rely on being implemented anyway, so it doesn't really change much
> > for a robust client.
> >
> >> so ignoring the warning because YANG says the default is current seems
> >> unwise.
> >
> > I do agree with this bit of conclusion, but sometimes after looking
> > at a warning and considering the larger context, ignoring the
> > warning *is* the right thing to do.
> >
> > Randy
> >
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>
> --
> Ladislav Lhotka, CZ.NIC Labs
> PGP Key ID: 0xB8F92B08A9F76C67
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