Re: [netmod] Y34

[Ladislav Lhotka <[e-mail]>]

> On 20 Jul 2015, at 17:00, Andy Bierman <[e-mail]> wrote:
> 
> 
> 
> On Mon, Jul 20, 2015 at 6:08 AM, Ladislav Lhotka <[e-mail]> wrote:
> 
> > 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.
> 
> 
> yes it is an issue.
> We need something to model a container full of arbitrary YANG data nodes.
> This is something that can be applied to the contents of a datastore.

anyxml can do that, too.

> 
>  
> 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.
> 
> The message encoding on the wire is not the same issue
> as the contents of a datastore.  Our server stores its own
> internal data structures.  XML, JSON, CBOR are just message
> encoding formats between client and server.  The datastore
> is not encoded in any of these formats.

The payload of anyxml needn’t directly map to a data subtree in the usual sense.

> 
> 
> 
>  
> 
> >
> > 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.
> 
> But a single container called "whatever" provides no such aggregation.
> You would need a list for that. And the NMS might have multiple
> layers of hierarchy to represent various aggregations.  The NP
> container called "device" is not helpful for aggregation.

The parent node can be a list as well. The “root” node would be like a mount point in a Unix filesystem.

Lada

> 
> 
> 
> Lada
> 
> 
> Andy
>  
> 
> >
> > 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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> >
> > --
> > Ladislav Lhotka, CZ.NIC Labs
> > PGP Key ID: E74E8C0C
> >
> >
> >
> >
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> 
> --
> Ladislav Lhotka, CZ.NIC Labs
> PGP Key ID: E74E8C0C
> 
> 
> 
> 
> 

--
Ladislav Lhotka, CZ.NIC Labs
PGP Key ID: E74E8C0C