Re: [core] Benjamin Kaduk's Discuss on draft-ietf-core-senml-more-units-04: (with DISCUSS and COMMENT)
Benjamin Kaduk <kaduk@mit.edu> Wed, 19 February 2020 17:01 UTC
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Date: Wed, 19 Feb 2020 09:01:26 -0800
From: Benjamin Kaduk <kaduk@mit.edu>
To: Carsten Bormann <cabo@tzi.org>
Cc: The IESG <iesg@ietf.org>, draft-ietf-core-senml-more-units@ietf.org, Jaime Jimenez <jaime@iki.fi>, core-chairs@ietf.org, core@ietf.org
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Subject: Re: [core] Benjamin Kaduk's Discuss on draft-ietf-core-senml-more-units-04: (with DISCUSS and COMMENT)
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Hi Carsten, Thanks for the updates; the changes in the -05 look good with just one exception. That, and some other comments, inline. On Wed, Feb 19, 2020 at 01:50:57PM +0100, Carsten Bormann wrote: > Hi Ben, > > thank you for your in-depth review. > > > ---------------------------------------------------------------------- > > DISCUSS: > > ---------------------------------------------------------------------- > > > > +-----------+-------------------+-------+-----------+-----+---------+ > > | secondary | description | SenML | scale | off | refer- | > > | unit | | unit | | set | ence | > > +-----------+-------------------+-------+-----------+-----+---------+ > > [...] > > | km | kilometer | km | 1000 | 0 | RFCthis | > > > > The associated SenML unit would be just 'm', not 'km'. > > Oops. Obviously, it is a consistency requirement that anything in column 3 needs to be present in the primary unit name registration table. > > Fixed in https://github.com/core-wg/senml-more-units/commit/78c714ab6a6526291265ec1976807ab3e8aa3138 > > > > ---------------------------------------------------------------------- > > COMMENT: > > ---------------------------------------------------------------------- > > > > I appreciate the compromise position that was achieved after the long > > last-call discussions questioning the need for this work. It seems like > > a reasonably shaped "escape hatch" to me. > > > > Section 2 > > > > I assume this is just a product of my personal background, but I am more > > used to "mass density" than "mass concentration" for dimensionalities > > such as kg/m3. > > True, the unit can be used for both quantities. > (The actual request leading up to this was for particle concentration meters, hence the mass concentration label.) > That factoid is actually covered in > https://www.iso.org/obp/ui/#iso:std:iso:80000:-1:ed-1:v1:en > Section 3.7, example 2. > Since the registry captures units, not quantities, I propose adding mass density to the parenthesis. > > Now in https://github.com/core-wg/senml-more-units/commit/25072a9e5757ea0d4aff75d2415afb40a17a9e37 > > > Section 3 > > > > o The Byte. [IEC-80000-13] defines both the bit (item 13-9.b) and > > the byte (item 13-9.c, also called octet) as alternative names for > > the coherent unit one for the purpose of giving storage capacity > > and related quantities. While the name octet is associated with > > > > nit: is "one" misplaced, here? > > The coherent unit actually is “one”; see Section 3.8, Note 3, and Section 3.12, Note 4 in ISO 80000-1 as cited above. > To make this easier to read, we could place it in quotes, except it is not a string, it is really the number 1. I guess I kind of gave it away that I didn't follow the reference, here :) It's probably too verbose to try something like "the coherent unit used for dimensionless quantities and indicated by the numeral one". > > Section 4 > > > > o scale, offset: two rational numbers, expressed in decimal > > (optionally, with a decimal exponent given) or as a fraction > > divided by a "/" character. > > > > nit: doesn't "a fraction divided by a '/' character" involve two '/' > > characters? That is, "1/2" is a fraction, so "1/2 divided by a '/' > > character" would be like "1/2/" or "1/2/2" or something nonsensical like > > that. > > “divided” as in “separated into two halves”, i.e., “1/2” is divided by a “/“ into a 1 and a 2. Maybe we need better phrasing here. Perhaps, "a fraction represented using a '/' character to separtae numerator and denominator"? > > It's a little surprising to see kibibyte and gigabyte defined but not > > gibibyte. > > It’s a registry, nobody asked for it yet… > We could do some more proactive registering. > > > names. Guidelines to the difference between units (which can go into > > the registry) and quantities are widely available, see for instance > > [RS] and [BIPM]. > > > > I suggest a parenthetical "(which cannot)" after "quantities". > > Very good. > > Now in https://github.com/core-wg/senml-more-units/commit/25072a9e5757ea0d4aff75d2415afb40a17a9e37 > > > > > Where the benefits of directly using a secondary unit in a SenML pack > > outweigh the obove considerations, the use of secondary units in "u" > > > > nit: s/obove/above/ > > (Covered earlier.) > > > specifically allows this and/or by using a field with a label name > > that ends with the "_" character ("must-understand" field) that > > specifically allows this. The definition of these versions and > > > > I suggest "whose definition specifically allows this". > > Good point. > > Now in > https://github.com/core-wg/senml-more-units/commit/76f51849541b5a18a6ef2984507284d92514eb54 > > > > > fields is outside the scope of the present specification; one such > > definition is provided in [I-D.bormann-core-senml-versions]. > > > > nit: I suggest "proposed definition" or "possible definition", as > > internet-drafts are "works in progress". > > Maybe shorter “..is proposed in”? > I’ve put that into > https://github.com/core-wg/senml-more-units/commit/8f2163a311e088a8cdfc30fa37df3a9f175c87e3 Sure. > > Section 5 > > > > potential single point of failure. Instead of pulling the registry > > in each individual instance of the code, the software update > > mechanism (or a similar, less frequently triggered mechanism) SHOULD > > be used to disseminate updated units registries obtained from IANA > > towards the instances via common repositories. > > > > I like how this blandly assumes that a software update mechanism is > > available. Optimistic for the present-day world, but still probably the > > right thing to say. > > nit: as written, "less frequently triggered mechanism" means "less > > frequently triggered than the software update mechanism", which I > > suspect is not the intent. > > I have turned this into > > (or a similar > mechanism visiting IANA less frequently) This is better, but I think that "less frequently" is still an implied comparison, and the comparison against software-update is more local than the (intended) comparison against the generic/abstract "usual frequency" or "every time an instance of the system starts up or checks". I might suggest "a similar mechanims that only visits IANA infrequently". > in https://github.com/core-wg/senml-more-units/commit/8656620080aa6d0d2a422476a7a5693e931e6f3e > > > Section 6 > > > > I suggest reiterating the implications of the requirements at the end of > > section 4, namely, that use of new units is "fail-safe", in that an > > implementation processing a pack using secondary units is guaranteed to > > have been developed with an awareness of the risks of having multiple > > units available for the same logical type. (It is not, of course, > > guaranteed to know about the specific secondary unit in question when > > just the "SenML Version" check is used, in the same way that current > > SenML applications are not guaranteed to know about units not in the > > initial allocation from RFC 8428.) > > > > The security considerations of [RFC8428] apply. The introduction of > > new measurement units poses no additional security considerations > > except from a possible potential for additional confusion about the > > proper unit to use. > > > > Nitpicking, but I think there's a related risk of confusion in terms of > > what quantity has been measured and is indicated in a SenML pack, as > > alluded to by the previous mention of "trigger[ing] on the presence of a > > quantity in a certain unit". > > I have tried to cover this in > https://github.com/core-wg/senml-more-units/commit/532dce8315bf9c75af1d1150d078d2f91e6444c0 Thanks for all the updates; I've removed my Discuss accordingly. -Ben
- [core] Benjamin Kaduk's Discuss on draft-ietf-cor… Benjamin Kaduk via Datatracker
- Re: [core] Benjamin Kaduk's Discuss on draft-ietf… Carsten Bormann
- Re: [core] Benjamin Kaduk's Discuss on draft-ietf… Benjamin Kaduk
- Re: [core] Benjamin Kaduk's Discuss on draft-ietf… Carsten Bormann