Re: [netmod] Y34

[Juergen Schoenwaelder <[e-mail]>]

Lada,

Y34 is closed and I have not seen any new argument here that indicates
we made a major mistake with the resolution of Y34. As such, Y34
remains closed.

If you want to discuss new ideas to relocate or "symlink" data models,
please do so in a separate thread. (And no, we do not accept new
issues for YANG 1.1 either at this point in time.)

/js

On Mon, Jul 20, 2015 at 07:42:49PM +0200, Ladislav Lhotka wrote:
> 
> > On 20 Jul 2015, at 19:29, Andy Bierman <[e-mail]> wrote:
> > 
> > 
> > 
> > On Mon, Jul 20, 2015 at 10:15 AM, Ladislav Lhotka <[e-mail]> wrote:
> > 
> > > 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.
> > 
> > 
> > the WG already decided it can't.
> > The extra XML PIs, etc. are not accepted by all servers, remember?
> > There is no use for the extra stuff in the datastore.
> >  I don't see why we need 2 anyxml constructs that are not
> > supported by the industry.  One is already too many.
> 
> I agree, but this is what we are going to have. My proposal was to have just one with two different names.
> 
> > 
> > 
> > >
> > >
> > > 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.
> > 
> > that's precisely the difference between anyxml and anydata.
> > The anydata node MUST map directly into data subtrees.
> 
> If the server doesn’t know the YANG data model at run time (which is possible) then it cannot do it - for instance, it cannot properly map module names to namespace URI or handle lists.
> 
> > 
> >  
> > 
> > >
> > >
> > >
> > >
> > >
> > > >
> > > > 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.
> > 
> > 
> > Are you saying all data on a device needs to be in a top-level list called 'device'
> > because an NMS might exist that  wants to have the datastores from lots of devices?
> > As Martin pointed out several times, the NMS can make its own container or
> > lists.  It does not need the device to mirror its own structure.
> 
> As I said, I don’t care that much about the “device” container. What would be really useful is to have the possibility to do e.g. this:
> 
> virtual-node* [name]
>     name
>     if:interfaces
>         ...
> 
> to support the use case where all virtual nodes are managed by the same NETCONF/RESTCONF server.
> 
> Lada
> 
> >  
> > 
> > 
> > Lada
> > 
> > Andy
> >  
> > 
> > >
> > >
> > >
> > > 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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> > > >
> > > >
> > > >
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> > >
> > > --
> > > Ladislav Lhotka, CZ.NIC Labs
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> > >
> > >
> > >
> > >
> > >
> > 
> > --
> > Ladislav Lhotka, CZ.NIC Labs
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> > 
> > 
> > 
> > 
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> --
> Ladislav Lhotka, CZ.NIC Labs
> PGP Key ID: E74E8C0C
> 
> 
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-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: [phone]         Campus Ring 1 | 28759 Bremen | Germany
Fax:   [phone]         <http://www.jacobs-university.de/>