Re: [netmod] [Technical Errata Reported] RFC7950 (6031)

Kent Watsen <kent+ietf@watsen.net> Thu, 23 April 2020 16:59 UTC

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From: Kent Watsen <kent+ietf@watsen.net>
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Date: Thu, 23 Apr 2020 16:59:06 +0000
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Cc: Radek Krejci <rkrejci@cesnet.cz>, Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>, =?utf-8?Q?Martin_Bj=C3=B6rklund?= <mbj+ietf@4668.se>, "netmod@ietf.org" <netmod@ietf.org>, "Rob Wilton (rwilton)" <rwilton=40cisco.com@dmarc.ietf.org>
To: Andy Bierman <andy@yumaworks.com>
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Subject: Re: [netmod] [Technical Errata Reported] RFC7950 (6031)
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The consensus seems to be that:
  - the errata should be rejected
        - Rob, do you agree?
  - YANG-next should fix it later
        - I created https://github.com/netmod-wg/yang-next/issues/104
  - implementations should try to do the right thing now
        - Radek’s suggestion below LGTM!


Tallies:
   - for reject: Andy, Martin, Juergen, and Kent 
   - for accept: Radek, and Balazs
   - unclear: Lada, Rob, and Jason


Kent // as co-chair


> On Apr 14, 2020, at 10:35 AM, Andy Bierman <andy@yumaworks.com> wrote:
> 
> Hi,
> 
> I agree with Juergen that this errata should be rejected and the issue resolved in yang-next.
> No IETF module should use this construct. It is easy to convert to an equivalent form that is not under dispute.
> 
> 
> Andy
> 
> 
> On Tue, Apr 14, 2020 at 6:40 AM Radek Krejci <rkrejci@cesnet.cz <mailto:rkrejci@cesnet.cz>> wrote:
> Hi,
> 
> Dne 09. 04. 20 v 17:26 Kent Watsen napsal(a):
>> 
>> 
>>> On Apr 6, 2020, at 3:42 AM, Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de <mailto:j.schoenwaelder@jacobs-university.de>> wrote:
>>> 
>>> The definition I found in RFC 8639 is this:
>>> 
>>>        leaf stream {
>>>          type stream-ref {
>>>            require-instance false;
>>>          }
>>>          mandatory true;
>>>          description
>>>            "Indicates the event stream to be considered for
>>>             this subscription.";
>>>        }
>>> 
>>> This could be changed to:
>>> 
>>>        leaf stream {
>>>          type leafref {
>>> 	    path "/sn:streams/sn:stream/sn:name";
>>>            require-instance false;
>>>          }
>>>          mandatory true;
>>>          description
>>>            "Indicates the event stream to be considered for
>>>             this subscription.";
>>>        }
>>> 
>> 
>> I can confirm that `yanglint` validates the module cleanly after this change.
>> 
>> 
>> 
>>> On Apr 6, 2020, at 7:38 AM, Martin Björklund <mbj+ietf@4668.se <mailto:mbj+ietf@4668.se>> wrote:
>>> 
>>> I think the correct fix is to change the text so that
>>> "require-instance" is not classified as a restriction and keep the
>>> default.  
>> 
>> Agreed.
>> 
>> 
>>> Also, I think that it would be easiest (for backwards
>>> compatibility w/ existing models) to allow "require-inetance" to be
>>> changed in derived types.
>>> 
>>> However, this cannot imo be done in an errata.
>> 
>> While I appreciate Radek and Michal’s perspective, I also think that is would be best for the community for `yanglint` to support this, as they are published modules doing it.
>> 
> 
> I don't feel as an expert for IETF processes, so I don't know if this issue can be solved in errata or not (and I'm not sure there is a consensus on this in mailing list). For the implementation, I would appreciate at least a consensus on a solution. So far I saw opinions to allow it, to disallow and also to make it implementation-specific (which means in fact to disallow from the authors perspective, since there can be a tool disallowing it and we are saying that such a tool is ok). So, there is no clear way for implementors, which means problems for interoperability - there will be always someone unhappy and so far I don't know what is the major opinion to go. 
> 
> So far, I tend to allow it (accept by libyang), but print warning to warn authors about possible problems (some tool can refuse such a module). Is it ok?
> 
> Radek
> 
> 
>> As an aside, I feel that all modules should be tested against all available validation tools during the publication process, but to find issues in the modules and well as possibly improve the tools.
>> 
>> Sadly, I only have `yanglint` and `yangson` available to me.  I just checked for the “yang validator” project, but both www.yangvalidator.com <http://www.yangvalidator.com/> and https://www.yangcatalog.org/yangvalidator <https://www.yangcatalog.org/yangvalidator> seem to be down.
>> 
>> 
>> Kent // contributor
>> 
> 
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