Re: [netmod] [Netconf] Alternative YANG library structure for 7895bis

[Andy Bierman <[e-mail]>]

Hi,

The per-datastore feature aspect of NMDA is a new and significant change to
YANG.

    |  |  +--ro feature* [name]
    |  |  |  +--ro name        yang:yang-identifier
    |  |  |  +--ro not-implemented-in*
    |  |  |              -> /yang-library/datastore/name


YANG does not define feature conformance at this granularity.
I strongly object to this change to YANG conformance.
A server can only advertise a YANG feature if it implemented on the entire
server.

This extra complexity is not present on the openconfig solution or
requirements.
Comparing any datastore to <operational> is much more complex (any may not
be possible)
if the features are different for a given module.

I do not see how <operational> can be true superset of the conventional
datastores
if the features are different.


Andy


On Wed, Nov 15, 2017 at 9:29 AM, Robert Wilton <[e-mail]> wrote:

> I don't think that this is really a good idea.  You would end up returning
> server metadata in addition to the configuration.
>
> I still think that the YANG library proposal is the best solution.
>
> Thanks,
> Rob
>
>
> On 16/11/2017 01:21, Vladimir Vassilev wrote:
>
> Hello,
>
> I have a proposal based on <get-data> that provides an elegant solution to
> consider as a 3rd option.  It is based on keeping exactly the same model as
> in RFC 7895 and using <get-data> RPC to retrieve datastore specific
> yang-library instance data in a similar way one would use <get-data> to
> retrieve the datastore contents. In addition a top level config=false
> container e.g. /datastores with list of supported datastores that does not
> need to be part of the yang-library module:
>
> module: ietf-datastores
> +--ro datastores
> |  +--ro datastore* [name]
> |     +--ro name          identityref
>
> Vladimir
>
> On 11/09/2017 05:51 PM, Robert Wilton wrote:
>
> Hi,
>
> Given some of the feedback related to the complexity of the YANG library
> bis structure, we have come up with two other possible structures for the
> YANG library data:
>
> (1) A simplified structure to make YANG library meet the NMDA
> requirements, but that is closer to the existing YANG library structure,
> and arguably simpler.
> (2) An enhanced version of the structure (1) above, that is also extended
> to allow the structure to be reused for schema-mount via an augmentation.
>
> For reference, at the end of this email, I have also included the tree
> diagram of the existing YANG library, and the current YANG library bis
> draft (draft-ietf-netconf-rfc7895bis-02) version.
>
> Considering the two new YANG library structures:
>
> ------------------------
>
> *(1) A simplified structure to make YANG library meet the NMDA
> requirements, but that is closer to the existing YANG library structure.*
>
> The main changes are:
> (i) Split "implemented modules" and "import-only-modules" into two
> separate lists, making the most important list (i.e. implemented modules)
> keyed by module name only and hence easier to reference.
> (ii) Assume modules are implemented in all datastores by default (with a
> "not-implemented-in" leaflist of datastores that a module is not
> implemented in).
> (iii) Assume that features are implemented in all datastores by default
> (with a "not-implemented-in" leaflist of datastores that a feature is not
> implemented in).
> (iv) Deleted module-sets.
> (v) Datastores are now just a list of supported datastores (that could
> potentially be extended with further per datastore properties in future).
>
> Manually generated tree output for proposed YANG library:
>
> module: ietf-yang-library
>  +--ro yang-library
>     +--ro modules
>     |  +--ro module* [name]
>     |  |  +--ro name           yang:yang-identifier
>     |  |  +--ro revision?      revision-identifier
>     |  |  +--ro schema?        inet:uri
>     |  |  +--ro namespace      inet:uri
>     |  |  +--ro submodule* [name]
>     |  |  |  +--ro name        yang:yang-identifier
>     |  |  |  +--ro revision?   yang:yang-identifier
>     |  |  |  +--ro schema?     inet:uri
>     |  |  +--ro not-implemented-in*
>     |  |  |              -> /yang-library/datastore/name
>     |  |  +--ro feature* [name]
>     |  |  |  +--ro name        yang:yang-identifier
>     |  |  |  +--ro not-implemented-in*
>     |  |  |              -> /yang-library/datastore/name
>     |  |  +--ro deviation*
>     |  |                 -> ../name
>     |  |
>     |  +--ro import-only-module* [name revision]
>     |     +--ro name                yang:yang-identifier
>     |     +--ro revision            union
>     |     +--ro schema?             inet:uri
>     |     +--ro namespace           inet:uri
>     |     +--ro submodule* [name]
>     |        +--ro name        yang:yang-identifier
>     |        +--ro revision    yang:revision-identifier
>     |        +--ro schema?     inet:uri
>     +--ro datastore* [name] // Allows future per datastore properties.
>     |  +--ro name          identityref
>     +--ro checksum       string
>
> ------------------------------
>
> *(2) An enhanced version of the structure (1) above, that is extended to
> allow the structure to be reused for schema-mount via an augmentation.*
>
> This is similar to the structure above, except that the "the set of
> modules" is contained in a list of named schema (e.g. similar to the schema
> mount draft), allowing this structure to be re-used for schema mount.
>
> Schema mount would be expected to augment yang-library to add in the
> additional schema mount information.  In the tree diagram, I have shown the
> schema-mount mount-point augmentation, but not including namespaces yet.
>
> Every server would be required to provide at least one schema in the
> schema list, and the primary schema for the device would always be given
> the name "primary".
>
> module: ietf-yang-library
>  +--ro yang-library
>     +--ro schema* [name]
>     |  +--ro name           string
>     |  +--ro checksum       string
>     |  +--ro module* [name]
>     |  |  +--ro name           yang:yang-identifier
>     |  |  +--ro revision?      yang:revision-identifier
>     |  |  +--ro schema?        inet:uri
>     |  |  +--ro namespace      inet:uri
>     |  |  +--ro submodule* [name]
>     |  |  |  +--ro name        yang:yang-identifier
>     |  |  |  +--ro revision?   yang:yang-identifier
>     |  |  |  +--ro schema?     inet:uri
>     |  |  +--ro not-implemented-in*
>     |  |  |              -> /yang-library/datastore/name
>     |  |  +--ro feature* [name]
>     |  |  |  +--ro name        yang:yang-identifier
>     |  |  |  +--ro not-implemented-in*
>     |  |  |              -> /yang-library/datastore/name
>     |  |  +--ro deviation*
>     |  |  |              -> ../name
>     |  |  +- schema-mount:mount-point* [label]
>     |  |     +--ro label         yang:yang-identifier
>     |  |     +--ro config?       boolean
>     |  |     +--ro (schema-ref)
>     |  |        +--:(inline)
>     |  |        |  +--ro inline?       empty
>     |  |        +--:(use-schema)
>     |  |           +--ro use-schema* [name]
>     |  |              +--ro name
>     |  |              |       -> /yang-library/schema/name
>     |  |              +--ro parent-reference*   yang:xpath1.0
>     |  |
>     |  +--ro import-only-module* [name revision]
>     |     +--ro name                yang:yang-identifier
>     |     +--ro revision            union
>     |     +--ro schema?             inet:uri
>     |     +--ro namespace           inet:uri
>     |     +--ro submodule* [name]
>     |        +--ro name        yang:yang-identifier
>     |        +--ro revision    yang:revision-identifier
>     |        +--ro schema?     inet:uri
>     +--ro datastore* [name] // Allows future per datastore properties.
>     |  +--ro name          identityref
>     +--ro checksum       string
>
> Please can you provide comments on these structures, in particular:
>
> Is this version better (i.e. simpler) that the version currently in
> draft-ietf-netconf-rfc7895bis-02 (below)?
>
> Should we try and make the structure extensible for schema-mount via
> augmentation (i.e. version (2)), or is it better that schema-mount has its
> own separate subtree?
>
> For reference only I have included the existing YANG library and YANG
> library bis draft tree diagrams.
>
> Thanks,
> Rob
>
>
> -----------------------------
>
> *** FOR REFERENCE ONLY ***
>
> (3)  The current YANG library structure in YANG library bis
> (draft-ietf-netconf-rfc7895bis-02)
>
>    module: ietf-yang-library
>        +--ro yang-library
>           +--ro modules
>           |  +--ro module* [id]
>           |     +--ro id                  string
>           |     +--ro name                yang:yang-identifier
>           |     +--ro revision?           revision-identifier
>           |     +--ro schema?             inet:uri
>           |     +--ro namespace           inet:uri
>           |     +--ro feature*            yang:yang-identifier
>           |     +--ro deviation* [module]
>           |     |  +--ro module    -> ../../id
>           |     +--ro conformance-type    enumeration
>           |     +--ro submodule* [name]
>           |        +--ro name        yang:yang-identifier
>           |        +--ro revision?   revision-identifier
>           |        +--ro schema?     inet:uri
>           +--ro module-sets
>           |  +--ro module-set* [id]
>           |     +--ro id        string
>           |     +--ro module*   -> ../../../modules/module/id
>           +--ro datastores
>           |  +--ro datastore* [name]
>           |     +--ro name          identityref
>           |     +--ro module-set
>           |             -> ../../../module-sets/module-set/id
>           +--ro checksum       string
>
> -----------------------------
>
> *** FOR REFERENCE ONLY ***
>
> (4)  The current YANG library structure (RFC 7895)
>
>       +--ro modules-state
>          +--ro module-set-id    string
>          +--ro module* [name revision]
>             +--ro name                yang:yang-identifier
>             +--ro revision            union
>             +--ro schema?             inet:uri
>             +--ro namespace           inet:uri
>             +--ro feature*            yang:yang-identifier
>             +--ro deviation* [name revision]
>             |  +--ro name        yang:yang-identifier
>             |  +--ro revision    union
>             +--ro conformance-type    enumeration
>             +--ro submodule* [name revision]
>                +--ro name        yang:yang-identifier
>                +--ro revision    union
>                +--ro schema?     inet:uri
>
>
>
>
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