Re: [core] Last Call: <draft-ietf-core-senml-more-units-02.txt> (Additional Units for SenML) to Proposed Standard

Cullen Jennings <> Tue, 22 October 2019 14:05 UTC

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From: Cullen Jennings <>
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Date: Tue, 22 Oct 2019 08:05:06 -0600
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Subject: Re: [core] Last Call: <draft-ietf-core-senml-more-units-02.txt> (Additional Units for SenML) to Proposed Standard
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I am strongly opposed to the secondary registry - it will significantly harm interoperability. This could be resolved by not adding the items in the secondary repository or by adding them to the main repository. 

Having a registry of stuff that may or may not work simply means that we will have less interoperability because what you can not decide what is valid SenML or not.  Sure some of the device vendors making things that produce SenML have thought this was a good idea in the past but I’d like to hear from a bunch of the people that have to process the SenML data that is produced and see if they think it is a good idea. 

The working group discussed this for a long time and was against the items that are being added to the secondary repository. 
If there is a large group of people that agree the consensus has changed, then this should simply be put in the main registry. Many people believe that since SenML is not meant to be human readable, having a canonical form of just meters with a floating point number is better than having both km, mm, and god only knows what else. 

I note the secondary repository add mm but not cm. How is this insanity going to work out? How will analytics code trying to process this data know what it can use or not use. If we are going down this path, this is the wrong way to do it. The right way is to define a set of all SI prefixes and say they can be used with any unit. 

> On Oct 16, 2019, at 11:42 AM, The IESG <> wrote:
> The IESG has received a request from the Constrained RESTful Environments WG
> (core) to consider the following document: - 'Additional Units for SenML'
>  <draft-ietf-core-senml-more-units-02.txt> as Proposed Standard
> The IESG plans to make a decision in the next few weeks, and solicits final
> comments on this action. Please send substantive comments to the
> mailing lists by 2019-10-30. Exceptionally, comments may be
> sent to instead. In either case, please retain the beginning of
> the Subject line to allow automated sorting.
> Abstract
>   The Sensor Measurement Lists (SenML) media type supports the
>   indication of units for a quantity represented.  This short document
>   registers a number of additional unit names in the IANA registry for
>   Units in SenML.  It also defines a registry for secondary units that
>   cannot be in SenML's main registry as they are derived by linear
>   transformation from units already in that registry; RFC 8428 is
>   updated to also accept these units.
> The file can be obtained via
> IESG discussion can be tracked via
> No IPR declarations have been submitted directly on this I-D.
> _______________________________________________
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