Jürgen, all,

I see the irony in changing the YANG RFC(s) without updating the YANG language 
version number, but digging a bit deeper, I think the question is not as 
clear-cut as it might seem at first.

Altering the contents of the backwards-compatibility section of RFC 6020 (sec 
10) and RFC 7950 (sec 11) clearly implies changes in YANG module authors' 
behavior.

Speaking as a YANG compiler implementor, however, I don't see any changes that 
have to made to the compiler because of this RFC change. There are no new 
keywords, none are removed. There is no change in the meaning of existing 
keywords. There is no difference in the output the compiler needs to generate.

So while there are changes to the YANG *standard* (meaning RFCs) there is no 
actual change to the YANG *language*. If we require user's to mark their 
modules with version 1.2 (or 2.0), from the compiler's pov, that would just be 
an alias for YANG 1.1. It means a fair amount of trouble to update all the 
tools out there to accept "yang-version 1.2" but do nothing new. It also adds a 
burden to YANG module implementors, since they would have to go through all 
YANG 1.1 modules and mark them 1.2, for no change in meaning. For organizations 
with some modules still on YANG 1.0, the bar is even higher.

I think the most pragmatic approach in this case would be to change the RFC 
text in the backwards-compatibility sections and not update the yang-version 
number as long as no change is required in the compilers. If anyone can point 
to actual things the compiler needs to do differently, I'd be interested to 
hear.

Best Regards,
/jan



> On 12 Sep 2023, at 07:55, Jürgen Schönwälder 
> <[email protected]> wrote:
> 
> I disagree with the poll. There are important teachnigal differences
> behind the two options that this polls tries to hide.
> 
> Updating YANG 1 and YANG 1.1 means creating YANG 1' and YANG
> 1.1'. There is no way that a new versioning approach will be
> understood by existing YANG tooling. That's an illusion.
> 
> /js
> 
> On Mon, Sep 11, 2023 at 10:39:39PM +0000, Kent Watsen wrote:
>> WG,
>> 
>> Please help the YANG-versioning effort move forward by participating in the 
>> following poll:
>> 
>>  - https://notes.ietf.org/netmod-2023-sept-poll  (Datatracker login required)
>> 
>> Kent and Lou
>> 
> 
>> _______________________________________________
>> netmod mailing list
>> [email protected]
>> https://www.ietf.org/mailman/listinfo/netmod
> 
> 
> -- 
> Jürgen Schönwälder              Constructor University Bremen gGmbH
> Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
> Fax:   +49 421 200 3103         <https://constructor.university/>
> 
> _______________________________________________
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