On Tue, 2017-12-19 at 07:49 -0500, Lou Berger wrote:
>
> On 12/19/2017 7:36 AM, Ladislav Lhotka wrote:
> > On Tue, 2017-12-19 at 06:43 -0500, Lou Berger wrote:
> > > Hi Lada,
> > >
> > > On 12/19/2017 6:23 AM, Ladislav Lhotka wrote:
> > > > On Tue, 2017-12-19 at 06:20 -0500, Lou Berger wrote:
> > > > > Lada,
> > > > >
> > > > >
> > > > > On December 19, 2017 1:12:35 AM Ladislav Lhotka <lho...@nic.cz> wrote:
> > > > >
> > > > > > On Mon, 2017-12-18 at 15:30 -0500, Lou Berger wrote:
> > > > > > > lada,
> > > > > > >
> > > > > > > See below.
> > > > > > >
> > > > > > >
> > > > > > > On 12/15/2017 8:59 AM, Ladislav Lhotka wrote:
> > > > > > > > Hi,
> > > > > > > >
> > > > > > > > unfortunately, using an action for querying embedded YANG
> > > > > > > > library
> > > > > > > > data
> > > > > > > > (needed for the "inline" case of schema mount) doesn't work
> > > > > > > > either
> > > > > > > > because now under NMDA actions can be used only on instances in
> > > > > > > > the
> > > > > > > > <operational> datastore.
> > > > > > >
> > > > > > > but the inline/embedded library would (only) be present in the in
> > > > > > > the
> > > > > > > operational datastore, so what's the issue?
> > > > > >
> > > > > > Well, the issue is described in my initial mail of this thread: the
> > > > > > current
> > > > > > text
> > > > > > requires that every instance of an inline mount point contains the
> > > > > > embedded
> > > > > > YANG library. Tha latter is state data, so the above requirement
> > > > > > cannot
> > > > > > be
> > > > > > satisfied if the mount point instance is in a configuration
> > > > > > datastore.
> > > > > >
> > > > >
> > > > > That's not how I read the intent of the current text. I don't see SM
> > > > > impacting which data stores information is presented. Just like use
> > > > > of
> > > > > scheme mount doesn't transform RO configuration information into
> > > > > operational information. I sent you a couple of sentences clarifying
> > > > > this
> > > > > at one point, I'll dig up the proposed text and resend.
> > > >
> > > > Please do, this has to be discussed in the WG mailing list.
> > >
> > > Agreed - that's why I asked to start this thread!
> > >
> > > Here's the original proposal:
> > >
> > > How about at the end of the section [3.2] adding a new
> > > paragraph along the lines of:
> > >
> > > It is important to note that both YANG Library and Schema
> > > Mount Modules contain only operational state data. As such,
> >
> > s/contain/define/
> >
> > > the information in these modules should be retrieved by
> > > clients from operational data stores using the appropriate
> >
> > This is based on two assumptions:
> >
> > 1. For every configuration datastore there is a corresponding operational
> > datastore.
>
> well the text is revised below. In any case, "these modules" refers to
> yang library, and yes, I'm assuming YL is always and only in
> operational. If the revised text below isn't clear s/these/YANG Library/ -
The thing is that we have the top-level YANG library in <operational>, and then
embedded YANG libraries scattered inside inline mount point instances.
>
> >
> > 2. For every mount point instance in any configuration datastore there is a
> > corresponding mount point instance (with the same path) in an operational
> > datastore.
> >
> > I think that neither of these has to be true in general.
>
> agreed in general, but for inline, where YL is required, it must be true.
How do you know? I provided an example in Singapore where a mount point instance
in <intended> is a part of pre-provisioned data (for non-existent hardware).
Then, according to the NMDA rules there is no corresponding instance in
<operational>, hence no place where the embedded YANG library can be placed.
(I can easily provide a concrete example if needed).
Dean replied that this cannot happen, so it seems there are some assumptions how
the inline method of schema mount may be applied. If so, these assumptions have
to be explicitly stated.
>
> >
> > > protocol operations.
> >
> > In contrast, the substance of my proposal with metadata annotations is to be
> > able to retrieve all schemas from a well-known location in *the*
> > <operational>
> > datastore, namely from the top-level YANG library.
>
> What about a schema that is based on dll that contains modules that
> isn't loaded until a mount point is instantiated -- this is certainly a
> valid approach for supporting LNEs, but would be precluded in this
> approach. I really don't think a top level approach works for all
> inline (managed) types of mounts.
It isn't precluded: when the mount point is instantiated (no matter which
datastore it is in), the server adds the schema as a new entry to the "schema"
list in the top level YANG library (with a unique key), and annotates the mount
point instance with a leafref pointing to that key. So different instances of
the same mount point can have different schemas.
>
> >
> > > Given this discussion, we can generalize it further to:
> > >
> > > The use of mount points does not impact the nature of the
> > > mounted data or in which data store information is made
> > > available. For example, mounted YANG Library modules contain
> > > only operational state data and, as such, the information in
> > > these modules is available from operational data stores using
> > > the appropriate protocol operations.
> >
> > The whole question here is whether and how we can locate the schema for an
> > inline mount point in any configuration datastore.
>
> Why is a mounted YL different than a top level YL? What works for and
It is not different, but it can be only in an operational datastores, and so for
mount point instances inside configuration datastores we need a way how to
locate the schema for that mount point, because it cannot be found directly
under the mount point instance (as the current text assumes).
> is sufficient for the normal case of YL shouldn't be impacted or
> modified by SM -- at least that's how I thought we've been talking about
> since SM was started. Again, we never made any special provisions for
> any other rw/ro/state data, assuming top level YL is not handled as
> metadata, why start now?
>
> I'm getting the impression that your argument may be more about if YL
> should be treated as something other than operational data, is this wrong?
This is wrong. My argument is that there should be only one top-level YANG
library (state data) and each inline mount point instance just points to a
schema inside it by means of a metadata annotation attached to the mount point
(in any datastore).
Lada
>
> Thanks,
> Lou
>
> > Lada
> >
> > > Lou
> > >
> > > > Lada
> > > >
> > > > > Lou
> > > > > > > > However, a good alternative seems to be a metadata annotation
> > > > > > > > along
> > > > > > > > the
> > > > > > > > lines of RFC 7952, for example with the alternative B of the
> > > > > > > > newly
> > > > > > > > proposed YANG library schema:
> > > > > > > >
> > > > > > > > md:annotation schema-ref {
> > > > > > > > type leafref {
> > > > > > > > path "/yanglib:yang-
> > > > > > > > library/yanglib:schema/yanglib:name";
> > > > > > > > }
> > > > > > > > }
> > > > > > > >
> > > > > > > > In other words, all inline mounted schemas would be included in
> > > > > > > > the
> > > > > > > > top-level YANG library, and mount point instances in all
> > > > > > > > datastores
> > > > > > > > would be annotated with leafref pointing to the actual schema.
> > > > > > > >
> > > > > > > > Unlike regular state data, it is IMO no problem to permit such
> > > > > > > > annotations in configuration datastores.
> > > > > > > >
> > > > > > > > Opinions?
> > > > > > >
> > > > > > > I'm not sure this will work for all architectures of LNEs as well
> > > > > > > as
> > > > > > > other possible future use cases. In short, this seems *very*
> > > > > > > restrictive.
> > > > > >
> > > > > > I don't understand, IMO it is not restrictive at all. What kind of
> > > > > > restrictions
> > > > > > do you see?
> > > > > >
> > > > > > Lada
> > > > > >
> > > > > > > Lou
> > > > > > >
> > > > > > > > Thanks, Lada
> > > > > > > >
> > > > > > > > Ladislav Lhotka <lho...@nic.cz> writes:
> > > > > > > >
> > > > > > > > > Hi,
> > > > > > > > >
> > > > > > > > > the following text in sec. 3.2 of schema-mount-08 is wrong for
> > > > > > > > > traditional
> > > > > > > > > datastores, and even more so for NDMA:
> > > > > > > > >
> > > > > > > > > In case 1 ["inline"], the mounted schema is determined at
> > > > > > > > > run
> > > > > > > > > time:
> > > > > > > > > every
> > > > > > > > > instance of the mount point that exists in the parent tree
> > > > > > > > > MUST
> > > > > > > > > contain a copy of YANG library data [RFC7895] that defines
> > > > > > > > > the
> > > > > > > > > mounted schema exactly as for a top-level data model. A
> > > > > > > > > client
> > > > > > > > > is
> > > > > > > > > expected to retrieve this data from the instance tree,
> > > > > > > > > possibly
> > > > > > > > > after
> > > > > > > > > creating the mount point. Instances of the same mount
> > > > > > > > > point
> > > > > > > > > MAY
> > > > > > > > > use
> > > > > > > > > different mounted schemas.
> > > > > > > > >
> > > > > > > > > An instance of the mount point in any *configuration*
> > > > > > > > > datastores
> > > > > > > > > cannot
> > > > > > > > > contain
> > > > > > > > > YANG library (being state data), and so the MUST cannot hold.
> > > > > > > > >
> > > > > > > > > It is not clear to me how to repair this without considerable
> > > > > > > > > complications
> > > > > > > > > and/or a lot of handwaving. There is actually one good
> > > > > > > > > solution
> > > > > > > > > but it
> > > > > > > > > has
> > > > > > > > > impact on YANG library: the server could provide it in a reply
> > > > > > > > > to
> > > > > > > > > an
> > > > > > > > > operation,
> > > > > > > > > say "get-yang-library" rather than as state data. Then
> > > > > > > > > everything
> > > > > > > > > would be
> > > > > > > > > fine
> > > > > > > > > - this operation would turn into an action for the mount
> > > > > > > > > point,
> > > > > > > > > and it
> > > > > > > > > can
> > > > > > > > > be
> > > > > > > > > used equally well for config true and false mount points.
> > > > > > > > >
> > > > > > > > > So my proposal is to move from YANG library as state data to
> > > > > > > > > an
> > > > > > > > > operation.
> > > > > > > > > It
> > > > > > > > > could be done along with changing the YANG library structure,
> > > > > > > > > so
> > > > > > > > > there
> > > > > > > > > will be
> > > > > > > > > little extra impact on implementations.
> > > > > > > > >
> > > > > > > > > Lada
> > > > > > > > >
> > > > > > > > > --
> > > > > > > > > Ladislav Lhotka
> > > > > > > > > Head, CZ.NIC Labs
> > > > > > > > > PGP Key ID: 0xB8F92B08A9F76C67
> > > > > > > > >
> > > > > > > > > _______________________________________________
> > > > > > > > > netmod mailing list
> > > > > > > > > netmod@ietf.org
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> > > > > > >
> > > > > > > _______________________________________________
> > > > > > > netmod mailing list
> > > > > > > netmod@ietf.org
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> > > > > >
> > > > > > --
> > > > > > Ladislav Lhotka
> > > > > > Head, CZ.NIC Labs
> > > > > > PGP Key ID: 0xB8F92B08A9F76C67
> > > > > >
>
>
--
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67
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