To: "netmod@ietf.org" <netmod@ietf.org>, Martin Bjorklund <mbj@tail-f.com>,
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From: Robert Wilton <rwilton@cisco.com>
Message-ID: <4b1cec2b-3ad5-5650-08af-e297473b4c63@cisco.com>
Date: Fri, 10 Nov 2017 13:35:38 +0000
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Archived-At: <https://mailarchive.ietf.org/arch/msg/netmod/b628YLMZOcc6W5HOZtEqwNfVrXY>
Subject: Re: [netmod] WG Last Call: draft-ietf-netmod-schema-mount-07
Precedence: list



On 09/11/2017 18:16, Juergen Schoenwaelder wrote:
> On Thu, Nov 09, 2017 at 05:38:40PM +0000, Robert Wilton wrote:
>>>>>> 3. Sec 2.1 Glossary of New Terms:  "Schema" isn't actually defined
>>>>>> anywhere (RFC 7950 doesn't define this).  Should it be defined here?
>>>>>> The NMDA datastores draft had a similar issue and we choose to define
>>>>>> "datastore schema" instead.
>>>>> I think the right place for defining the term "schema" (and "data model"
>>>>> as well) is the specification of YANG because it is desirable that all
>>>>> documents related to YANG use the same meaning.
>>>> OK, 7950 doesn't define it today.  Is that a problem?
>>> "Schema tree" and "schema node" are defined and used a lot in 7950, so
>>> it might be good to define "schema" as well - meaning the schema tree
>>> with all associated semantics.
>> OK, but we can't add definitions to 7950 now.  Would it make sense to add
>> the definition to the NMDA draft and reference that?
> So what is the difference between "schema tree" and "schema"? Or to
> put it differently, what is "all associated semantics" that you are
> adding to a "schema tree" to obtain a "schema"? RFC 7950 says:
>
>     o  schema tree: The definition hierarchy specified within a module.

When I read this definition of schema tree, it makes me think that it 
applies to only a single module.  E.g. you could have the ietf-ip schema 
tree, or the ietf-interfaces schema tree, etc.

But I think of a"schema" as being the tree structure of all schema nodes 
for a defined set of modules.


>
> If I understand 'definition hierarchy' correctly, than it seems
> "schema" is just an abbreviation of "schema tree", i.e., there is no
> semantic difference between these two terms. If there is a difference,
> we need to be able to spell it out.

So, if "schema tree" refers to the schema nodes in one module, I think 
"schema" is different from "schema tree".  But perhaps I'm 
misinterpreting the "schema tree" definition.

Thanks,
Rob


>
> /js
>