Re: [netmod] Query about draft-ietf-netconf-rfc7895bis-06

Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> Wed, 09 May 2018 09:54 UTC

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Date: Wed, 9 May 2018 11:53:52 +0200
From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
To: Rohit R Ranade <rohitrranade@huawei.com>
Cc: "netmod@ietf.org" <netmod@ietf.org>
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Subject: Re: [netmod] Query about draft-ietf-netconf-rfc7895bis-06
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On Wed, May 09, 2018 at 09:12:12AM +0000, Rohit R Ranade wrote:
> On Wed, May 09, 2018 at 02:31:15AM +0000, Rohit R Ranade wrote:
> > Hi All,
> > 
> > 
> > 1.       "import-only-module" is currently under the "module-set" list. How does the client benefit by learning which module-set imports which modules ?
> 
>               All non import-only modules of the schema are implemented
>               with their associated features and deviations.
> 
> Modules in module-set/module are modules a datastore referencing the module set implements, modules in module-set/import-only-module are modules a datastore referencing the module set only imports from.
>  
> > 2.       Whether we can keep the "import-only-module" as a sibling to module-set. And let it list all the imported modules.
> 
> A module set is a self contained set of modules and import only modules.
> 
> [Rohit R Ranade] One use-case I thought of was that a client was concerned with only some data-stores. So they can download the schema of only those modules and their imported modules of their data-stores of interest. But if this was the case, then the "checksum" is of no use to them, as they will not know whether their intended data-store changed or not. Is there any other use-case for the import-only-module being part of module-set ?

The checksum indicates a change in YANG library. If a client is only
interested in some datastore schemas, then the client may reload data
even though the specific datastore schema did not change. There were
versions with more checksum objects but at the end we removed them and
kept only the one that is essential to keep. Note, if you use
RESTCONF, then ETAGS may help with more granular checks. (In fact,
instead of spreading checksum objects all over, it seems RESTCONF does
not really need them and if NETCONF needs more granular chance checks,
it seems a generic solution that can work on arbitrary subtrees is a
better solution than spreading checksum objects everywhere.

The use-case for import-only-modules being part of a module set is to
allow a module-sets to be referential complete, i.e., different
module-sets may have diffferent import-only-modules.
 
> > 4.       Also I feel the text about "netconf-capability-change" notification based on yang-library checksum should be moved to the NETCONF NMDA draft.  Is it not more suitable there ?
> 
> The reason is that NMDA is a very generic architectural document and as such it should not detail specifics of concrete notifications.
> These details belong into the specific documents. The NMDA document is a root of a document dependency tree, we should not create a mesh of document dependencies.
> [Rohit R Ranade] Please note I mentioned " should be moved to the NETCONF NMDA draft ", by which I meant draft-ietf-netconf-nmda-netconf-05, not the RFC 8342

Sorry for my mis-understanding. YANG library defines the checksum and
the checksum may trigger a netconf-capability-change notification, so
this is likely why talk about the netconf-capability-change notification
in YANG library.

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
Fax:   +49 421 200 3103         <https://www.jacobs-university.de/>