Re: [netmod] yang-data-ext issues

Ladislav Lhotka <lhotka@nic.cz> Thu, 26 April 2018 05:53 UTC

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From: Ladislav Lhotka <lhotka@nic.cz>
To: Andy Bierman <andy@yumaworks.com>
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Subject: Re: [netmod] yang-data-ext issues
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Ladislav Lhotka <lhotka@nic.cz>; writes:

> On Wed, 2018-04-25 at 08:04 -0700, Andy Bierman wrote:
>> 
>> 
>> On Wed, Apr 25, 2018 at 7:05 AM, Ladislav Lhotka <lhotka@nic.cz>; wrote:
>> > On Wed, 2018-04-25 at 15:55 +0200, Juergen Schoenwaelder wrote:
>> > > On Tue, Apr 24, 2018 at 04:36:01PM +0200, Martin Bjorklund wrote:
>> > > > Ladislav Lhotka <lhotka@nic.cz>; wrote:
>> > > > > Martin Bjorklund <mbj@tail-f.com>; writes:
>> > > > > 
>> > > > > > Hi,
>> > > > > > 
>> > > > > > I am not sure what this statement tells us re. the issue in this
>> > email
>> > > > > > thread.
>> > > > > 
>> > > > > It tells us that, in my view, the approach taken in this document is a
>> > > > > bad idea.
>> > > > 
>> > > > Do you mean that the WG shoud drop this document?  And people that
>> > > > need yang-data should continue to use the version in 8040?  Or that
>> > > > people that need yang-data do not have a valid use case and they
>> > > > should do something else?
>> > > 
>> > > One option is that people use yang-data as defined in RFC 8040 until
>> > 
>> > IMO, people should use plain YANG. With the new YANG library it will be
>> > possible
>> > to confine such non-NM schemas in a special datastore so that the intention
>> > should be clear and multi-module schemas with all the additional data
>> > (versions,
>> >  features, deviations) can be used.
>> > 
>> 
>> I don't see how yang-data interferes with "plain YANG" at all.
>> It is for data that is not in scope for plain YANG.
>
> My question is why this extension is needed in the first place.

For example, RFC 8040 could have used two modules instead of
"ietf-restconf", one with the contents of grouping "errors" and the
other with the contents of grouping "restconf". No extension.

What would be wrong with this solution? Instead, the reader is
overwhelmed with the complexity of the "yang-data" definition, and most
tools cannot process the module.

Lada

>
>> A plain client can ignore yang-data and not affect and RPC, notification, or
>> data
>> definitions in plain YANG.
>
> A plain (NC/RC) client should never see such data even if it is not protected by
> yang-data in YANG. On the other hand, tools will be able to process such schemas
> (generate the ascii tree, convert it to something else, generate sample
> instances etc.) without explicitly supporting yang-data.
>
> Lada
>
>> 
>>  
>> > Lada
>> > 
>> 
>> Andy
>>  
>> > > there is a version of YANG that has a proper and complete integrated
>> > > solution. (If for example yang-data is used to declare error content
>> > > for RPCs, then more extensions are needed or a proper integration into
>> > > YANG. Is it really good to introduce augment-yang-data (instead of
>> > > making augment work with say 'data' in YANG 1.2)? And then we do
>> > > uses-yang-data etc.
>> > > 
>> > > /js
>> > > 
>> > -- 
>> > Ladislav Lhotka
>> > Head, CZ.NIC Labs
>> > PGP Key ID: 0xB8F92B08A9F76C67
>> > 
>> > _______________________________________________
>> > netmod mailing list
>> > netmod@ietf.org
>> > https://www.ietf.org/mailman/listinfo/netmod
>> 
>> 
> -- 
> Ladislav Lhotka
> Head, CZ.NIC Labs
> PGP Key ID: 0xB8F92B08A9F76C67
>
> _______________________________________________
> netmod mailing list
> netmod@ietf.org
> https://www.ietf.org/mailman/listinfo/netmod

-- 
Ladislav Lhotka
Head, CZ.NIC Labs
PGP Key ID: 0xB8F92B08A9F76C67