Re: [netmod] IETF 108: Summary of insignificant whitespace changes and versioning

Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de> Thu, 13 August 2020 10:23 UTC

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Date: Thu, 13 Aug 2020 12:23:02 +0200
From: Juergen Schoenwaelder <j.schoenwaelder@jacobs-university.de>
To: Ladislav Lhotka <ladislav.lhotka@nic.cz>
Cc: "Joe Clarke (jclarke)" <jclarke@cisco.com>, "netmod@ietf.org" <netmod@ietf.org>
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Subject: Re: [netmod] IETF 108: Summary of insignificant whitespace changes and versioning
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On Thu, Aug 13, 2020 at 11:37:18AM +0200, Ladislav Lhotka wrote:
> 
> 
> $ pyang -f yin ietf-inet-types.yang | xmllint --c14n - | sha256sum
> 8d1ca8f30566ce8cbeffa095e20642f8f6e9f3a724286be4ead863b4467dc40b  -
> 
> might be a very good start. It is certainly much more robust than
> relying on a simple checksum of the YANG module text.

This work started with the need for _semantic_ version numbers and now
we are down to hashes of modules? Do we still have a clear idea which
problem we are solving?

- Sane development environments use version control systems, we should
  in my view not attempt to go there. We should assume that people
  developing YANG modules use version control systems to track
  changes.

- There apparently is a need for a packaging system that can express
  which combinations of YANG module version are known to work
  together.

The YANG versioning work was driven (I think) by the desire to
support non-backwards compatible changes (section 4 of
draft-ietf-netmod-yang-versioning-reqs-03). Why do we end up
discussing how to calculate hashes or the impact of whitespace
changes? Whitespace and layout changes are backwards compatible,
even today's YANG versioning rules handle them well.

/js

-- 
Juergen Schoenwaelder           Jacobs University Bremen gGmbH
Phone: +49 421 200 3587         Campus Ring 1 | 28759 Bremen | Germany
Fax:   +49 421 200 3103         <https://www.jacobs-university.de/>