Dne 12. 09. 23 v 14:43 Jan Lindblad (jlindbla) napsal(a):
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.

I agree with this. I have actually always thought that the section "Updating a Module" should never have become part of the YANG language definition. A sensible approach could IMO be to move this section to 8407bis, and relax the requirements to SHOULD there.

Lada


Best Regards,
/jan



On 12 Sep 2023, at 07:55, Jürgen Schönwälder 
<jschoenwaelder@constructor.university> 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


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