Re: [netmod] Y34

[Ladislav Lhotka <[e-mail]>]

> On 20 Jul 2015, at 14:55, Andy Bierman <[e-mail]> wrote:
> 
> Hi,
> 
> Can you explain why we need 2 broken anyxmls?
> (The original and a synonym?)  The whole point of
> anydata is that it does not have XML cruft in it.

Yes, I understand this was your main priority. For implementors using off-the-shelf XML parsers and tools the XML cruft is not an issue at all.

Anyway, I believe there are use cases for arbitrary XML/JSON/CBOR/… with no (YANG) schema available. My only complaint to “anyxml” has always been that it is a misnomer for encodings other than XML.

> 
> I also don't get the value of a single top-level node called 'device'
> that every YANG model on the planet is supposed to augment.
> Can you explain why a protocol operation to retrieve the
> document root (/) is not sufficient for the top-level node?

I don’t intend to defend their model, the more serious problem IMO is that a model for a single device/function may be needed in another device that hosts many virtualised devices/functions of the former type. We don’t have a good solution for this rather typical situation.

Lada

> 
> Andy
> 
> 
> 
> On Mon, Jul 20, 2015 at 5:48 AM, Ladislav Lhotka <[e-mail]> wrote:
> 
> > On 20 Jul 2015, at 14:45, Ladislav Lhotka <[e-mail]> wrote:
> >
> > Hi,
> >
> > after listening to the presentation of
> > draft-rtgyangdt-rtgwg-device-model-00 at RTGWG session, I am wondering
> > whether the solution chosen for Y34 is really useful.
> >
> > The draft states they want to reuse ietf-interfaces but their tree in
> > fact is
> >
> >   +--rw device
> >          +--rw info
> >          |  +--rw device-type?   enumeration
> >          +--rw hardware
> >          +--rw interfaces
> >          |  +--rw interface* [name]
> >          |     ...
> >          +--rw qos
> >
> > So the "interfaces" container is no more a top-level node. There are
> > three possible options:
> >
> > 1. Change the ietf-interfaces module.
> > 2. Replicate its contents in another module.
> > 3. Extend YANG so that a *specific* schema tree can be grafted at a
> >   given data node.
> >
> > IMO #1 & #2 are really bad. I thought Y34-04 was essentially #3 but it
> > seems it is not so because it doesn't specify a concrete data model
> > that's allowed at a given location.
> >
> > On the other hand, the only real contribution of "anydata" over "anyxml"
> > is that is doesn't permit mixed content in XML, which is IMO not much.
> >
> > I know Y34 was already closed but I think it is more important to do
> > things right before YANG 1.1 becomes an RFC.
> >
> > What I want to propose is this:
> >
> > - Rename "anydata" as a synonym to "anyxml", and deprecate "anyxml" (but
> >  keep it for backward compatibility).
> 
> s/Rename/Introduce/
> 
> >
> > - Introduce a new statement and data node type, e.g. "root", that will
> >  extend the schema tree starting from that data node with a precisely
> >  specified data model. The specification can be same or similar as
> >  in yang-library.
> >
> > I believe there are other use cases in the existing modules. For
> > example, the ietf-routing module could simply define the data model for
> > a single routing instance (i.e. without "routing-instance" list at the
> > top), and it can be then used without changes on simple devices, and
> > more complex router implementations can graft it as a subtree under
> > "routing-instance", "networking-instance" or whatever.
> >
> > Lada
> >
> > --
> > Ladislav Lhotka, CZ.NIC Labs
> > PGP Key ID: E74E8C0C
> >
> > _______________________________________________
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> > https://www.ietf.org/mailman/listinfo/netmod
> 
> --
> Ladislav Lhotka, CZ.NIC Labs
> PGP Key ID: E74E8C0C
> 
> 
> 
> 
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--
Ladislav Lhotka, CZ.NIC Labs
PGP Key ID: E74E8C0C