Subject: [core] SenML FETCH/PATCH update

From: Ari Keränen <[email-masked]>
Date: Sun, 8 Mar 2020 23:34:30 +0000

CoRE WG, Adam & Ben,

I did now two PRs to address the final remaining IESG review comments from Ben [1] and Adam [2] for the SenML FETCH/PATCH draft:
https://github.com/core-wg/senml-etch/pull/16
https://github.com/core-wg/senml-etch/pull/17

If there are no objections, I'm planning to merge these and submit a new draft version before the DL.

This took a bit longer than intended and the changes were not quite as simple as initially thought. In particular it seems the must-understand fields extension mechanism used by SenML is better just passed through by the Patch mechanism. Otherwise generic Patch implementations would need to be aware of all future must-understand SenML fields. For Fetch mechanism extensibility can be achieved by standardizing new fields for selecting target records and by generating an error for any unexpected field instead of ignoring them by default.

To address Adam's discuss, the PR 17 makes now explicit that Patch records must match only one target record, they must be applied in sequence, invalid Patch Records result in an  error and rejecting the Patch Pack, and that rejected Patch Pack must not change the state of the Target Pack. Also added a note that each target record for Fetch Packs must appear only once in the reply, even if it would have been matched multiple times.

Cheers,
Ari

[1] https://datatracker.ietf.org/doc/draft-ietf-core-senml-etch/ballot/#benjamin-kaduk
[2] https://datatracker.ietf.org/doc/draft-ietf-core-senml-etch/ballot/#adam-roach