Re: [core] [SenML] Multiple values in a measurement

Michael Koster <michaeljohnkoster@gmail.com> Thu, 08 November 2018 18:17 UTC

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From: Michael Koster <michaeljohnkoster@gmail.com>
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Date: Thu, 8 Nov 2018 10:17:41 -0800
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Cc: Shantanoo Desai <des@biba.uni-bremen.de>, "fluffy@cisco.com" <fluffy@cisco.com>, "core@ietf.org" <core@ietf.org>
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Subject: Re: [core] [SenML] Multiple values in a measurement
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Hi Christian,

I don't believe RFC8428 places any normative constraints on the scope of the identifiers that result from bn+n, either in section 4.5.1 names or 4.6 resolved records. 

It recommends URI or URN, which aren't required to resolve to exclusive identifiers in any particular scope. 

It seems like the word global is carefully avoided, and there is an example that uses a local and possibly short-lived identifier scheme:

   [
     {"bn":"2001:db8::2/","bt":1.320078429e+09,
      "n":"temperature","u":"Cel","v":25.2},
     {"n":"humidity","u":"%RH","v":30},
     {"bn":"2001:db8::1/","n":"temperature","u":"Cel","v":12.3},
     {"n":"humidity","u":"%RH","v":67}
   ]

I other words, I think the concept of uniqueness needs to be allowed to be defined in the context of use cases that may be outside the scope of RFC8428 to limit.

Specifically, I don't imagine there being a senML validator that would check for the uniqueness of bn+n resolved names. I don't even know how right offhand.

What do the authors say?

Best regards,

Michael


> On Nov 7, 2018, at 11:18 PM, Christian Amsüss <christian@amsuess.com>; wrote:
> 
> On Wed, Nov 07, 2018 at 09:38:01AM -0800, Michael Koster wrote:
>> Or as an IPSO Smart Object representationfor the accelerometer object type (3313):
>> 
>> [
>>  {
>>    "bn": "3313/0/",
>>    "n": "5701",
>>    "vs": "rad/s",
>>  },
> 
> careful here: bn+n needs to be globally unique and can't rely on its
> retrieval URI to disambiguate.
> 
> Best regards
> Christian
> 
> -- 
> To use raw power is to make yourself infinitely vulnerable to greater powers.
>  -- Bene Gesserit axiom