[core] Alissa Cooper's Discuss on draft-ietf-core-senml-more-units-05: (with DISCUSS and COMMENT)
Alissa Cooper via Datatracker <noreply@ietf.org> Wed, 19 February 2020 19:24 UTC
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Date: Wed, 19 Feb 2020 11:24:25 -0800
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Subject: [core] Alissa Cooper's Discuss on draft-ietf-core-senml-more-units-05: (with DISCUSS and COMMENT)
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Alissa Cooper has entered the following ballot position for draft-ietf-core-senml-more-units-05: Discuss When responding, please keep the subject line intact and reply to all email addresses included in the To and CC lines. (Feel free to cut this introductory paragraph, however.) Please refer to https://www.ietf.org/iesg/statement/discuss-criteria.html for more information about IESG DISCUSS and COMMENT positions. The document, along with other ballot positions, can be found here: https://datatracker.ietf.org/doc/draft-ietf-core-senml-more-units/ ---------------------------------------------------------------------- DISCUSS: ---------------------------------------------------------------------- I have some questions and comments about the text below, which seems like it creates significant scope for interoperability failures: "Where the benefits of directly using a secondary unit in a SenML pack outweigh the above considerations, the use of secondary units in "u" fields MAY be enabled by indicating a new SenML version that specifically allows this and/or by using a field with a label name that ends with the "_" character ("must-understand" field) whose definition specifically allows this. The definition of these versions and fields is outside the scope of the present specification; one such definition is proposed in [I-D.bormann-core-senml-versions]." Do I understand correctly that this allows secondary units in (1) SenML packs that use some version number besides 10, and (2) SenML fields named with "_" that are in packs where the version number is 10? What is the motivation for providing two different mechanisms to signal that secondary units are in use? I.e., why isn't one or the other of these mechanisms sufficient? Without defining either a new version that supports secondary units or fields with "_", I don't understand how this update to RFC 8428 is complete enough to be implementable. It says other versions and fields are out of scope, but don't some need to be defined in order for the normative MAY in this text to be actionable? The label names registry policy is Expert Review, which does not require formal documentation of the registry entry. Where is the "definition [that] specifically allows this" expected to occur? Presumably some implementations are already using SenML. What is an implementation supposed to do if it encounters a label name containing "_" that it does not understand in a version 10 pack? It looks like this text went in a week ago but it's a pretty significant change to the extensibility story for SenML, so I'm wondering if the WG had a chance to come to consensus on it? I'm not super familiar with SenML so apologies if the answers to some of these questions are obvious. ---------------------------------------------------------------------- COMMENT: ---------------------------------------------------------------------- 'The unit "degrees" is in wide use in practice for plane angles (as in heading, bearing, etc.). It is marked with an asterisk because the preferred coherent SI unit is radian ("rad").' Is this asterisk notation meant to be common across all units that have this same property? If so, that seems worth specifying more generally, not just for degrees.
- [core] Alissa Cooper's Discuss on draft-ietf-core… Alissa Cooper via Datatracker
- Re: [core] Alissa Cooper's Discuss on draft-ietf-… Carsten Bormann
- Re: [core] Alissa Cooper's Discuss on draft-ietf-… Alissa Cooper
- Re: [core] Alissa Cooper's Discuss on draft-ietf-… Carsten Bormann
- Re: [core] Alissa Cooper's Discuss on draft-ietf-… Alissa Cooper
- Re: [core] Alissa Cooper's Discuss on draft-ietf-… Carsten Bormann