Re: [netmod] Comments on draft-ietf-netmod-schema-mount-09

Hi Amy,

On 27/03/2018 04:47, Yemin (Amy) wrote:
> Hi all,
>
> I also have a question/comment regarding this draft, maybe if it's discussed already.
>
> If there a model A, which I would like to use just part of model A in another model B, what should I do?
> The draft states that "This document allows mounting of complete data models only.  Other specifications may extend this model by defining additional mechanisms such as mounting sub-hierarchies of a module."
> It seems that the current schema mount doesn't support such usage.
That is correct.

>   
>
> Then I'm thinking that using deviation to create a new sub-module A', then mount the sub-module A' in model B.
> Will it be a possible way out?
If you have a module A, then you could create another module, 
A-deviations, that used deviation delete statements to remove parts of 
A's schema.

Then a server could mount both modules A and A-deviations, hence 
excluding parts of module A at the mount point.

However, this approach would not allow you to only mount a descendant 
subtree in A.  E.g. You couldn't just directly mount the 
"interfaces/interface/statistics" container from RFC 8343, but you could 
mount the ietf-interfaces module and then deviate delete all nodes 
except for the interfaces/interface/statistics container.

Thanks,
Rob

>
> BR,
> Amy
> -----Original Message-----
> From: netmod [mailto:netmod-bounces@ietf.org] On Behalf Of otilibil@eurecom.fr
> Sent: Monday, March 26, 2018 7:18 PM
> To: netmod@ietf.org
> Subject: [netmod] Comments on draft-ietf-netmod-schema-mount-09
>
> Hi members,
>
> I comment on that draft:
>
> * Instead of "it is often necessary that an existing module (or a set of modules) is added to the data model starting at a non-root location", this would read better: "it is often necessary that an existing module (or a set of modules) be added to the data model at locations other than the root." (Section 1)
>
> * 'The "mount-point" statement MUST NOT be used in a YANG version 1 module' Why this documents keeps YANG 1 off from its scope? (Section
> 3.1)
>
> * 'Specifically, a server that doesn?t support the NMDA, MAY implement revision 2016-06-21 of "ietf-yang-library" [RFC7950] under a mount point' [RFC7895] defines "ietf-yang-library", not [RFC7950] (Section 6)
>
> * Why not "Tree Diagram" instead of "Data Model"? The wording has become a Best Practice (Section 8)
>
> * Idem, "This document...has the following diagram" captures better the Best Practice than "This document...has the following structure"
> (Section 8)
>
> * Same remark on restricting to YANG 1.1: "The ?mount-point? statement MUST NOT be used in a YANG version 1 module, neither explicitly nor via a ?uses? statement (description of the extension "mount-point")
>
> * Should this sentence refers only to [RFC6020]? "This document registers a YANG module in the YANG Module Names registry [RFC6020]"
> (Section 10)
>
> * The document cites /schema-mounts as "The schema defined by this state data provides detailed information about a server implementation may help an attacker identify the server capabilities and server implementations with known bugs" I think this section should warn also
> on:
>      ** Section 2.1.2 and 4 of [RFC7895] (the list 'module' contains the leaf 'schema': from which anyone may retrieve a YANG module)
>      ** Section 3 of [RFC6022] (it defines the RPC 'get-schema'; with which anyone may get a YANG module)
>      ** and Section 5 of [RFC8341] (reminding administrators to set user rights accordingly, and giving their defaults values).
>
> Regards,
> Ariel
>
> [RFC6020] https://tools.ietf.org/html/rfc6020
> [RFC7895] https://tools.ietf.org/html/rfc7895
> [RFC7950] https://tools.ietf.org/html/rfc7950
> [RFC8341] https://tools.ietf.org/html/rfc8341
>
>
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