Status CoRE SenML

Author: Jaime Jiménez

Tentative Timeline

• draft summary
• IESG Submission @due(27-12-14 15:28)

Comments to authors on v11

• When defining the name field it would have been good to add an normative reference to RFC2141, RFC4122, RFC8141 or an informative one to section 4.3. Similarly the units could refer to section 12.1 and time to unix time. I am assuming this is intentional.
  • We have informative references for 4122 and 8141 but since those formats are not normative (just examples for generating unique name) I think informative reference is the right level. And 2141 was obsoleted by 8141.
• Which is the implementation status of the draft?
  • RIOT OS, CISCO.
    
• A formal review is required for new registries. Has this been initiated?
  • For the IANA registries, the IANA review is done normally when publication is requested; Assumption is that there is no need for author actions here.
• A formal review is required for new media types on section 12.3. Have you checked that with media-types@iana.org?
  • Yes.
• Have you initiated the process for the Units and Labels registry?
  • Again, for the IANA registries, the IANA review is done normally when publication is requested; Assumption is that there is no need for author actions here.
• Have you validated the CDDL in Section11?
  • The examples in the draft are checked automatically with the CDDL and RelaxNG when draft is built

Editorial

• There are many types of more complex measurements and measurements that this media type would not be suitable for.
• a concept of a

Summary draft-ietf-core-senml-12

Media Types for Sensor Markup Language (SenML)

The specification defines media types for representing simple sensor measurements in Sensor Measurement List (SenML). The draft explains the structure and semantics of SenML and how to represent it in its four serializations. It comes with 6 base fields:

• base name: normally the endpoint name in URN or UUID format.
• base time: unix time when the measurement was taken.
• base unit: defines a new Units Registry inspired from NIST and UCUM.
• base value: the actual measurement value.
• base sum: sum of values over time.
• version: media type format version.

Base values help compress the information not to repeat fields. Multiple measurements are taken in an incremental fashion adding to the base value. Similarly JSON, XML and CBOR labels help compress a bit more.It allows for representing measurements with individual and multiple datapoints, as well as various data types and collections.

Single datapoint:

[
    {"n":"urn:dev:ow:10e2073a01080063","u":"Cel","v":23.1}
]

Multiple:

[
  {"bn":"urn:dev:ow:10e2073a01080063:","n":"voltage","u":"V","v":120.1},
  {"n":"current","u":"A","v":1.2}
]

Collections:

[
    {"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}
]

It also allows for fragment record identifiers to select portions of a senml resource representation. For example the 3rd and 5th record can be selected with:

coap://example.com/temp#rec=3,5

The draft also introduces CDDL descriptions for the JSON and CBOR representations as well as the CBOR labels.

There are several implementations available, Cisco’s [1], Leshan [2] and RIOT OS [3].

[1] https://github.com/cisco/senml

[2] https://github.com/eclipse/leshan/tree/master/leshan-core/src/main/java/org/eclipse/leshan/json

[3] https://github.com/backenklee/RIOT/tree/senml-experimental

Shepherd Writeup

Summary

• Document Shepherd: Jaime Jiménez, jaime.jimenez@ericsson.com
• Area Director: Alexey Melnikov, aamelnikov@fastmail.fm

This specification defines media types for representing simple sensor measurements and device parameters in the Sensor Measurement Lists (SenML). Representations are defined in JavaScript Object Notation (JSON), Concise Binary Object Representation (CBOR), eXtensible Markup Language (XML), and Efficient XML Interchange (EXI), which share the common SenML data model. A simple sensor, such as a temperature sensor, could use this media type in protocols such as HTTP or CoAP to transport the measurements of the sensor or to be configured.

The document is intended for Standards Track.

Review and Consensus

The document has gone through multiple expert reviews and has been discussed on multiple IETF meetings. Before the last IETF the WGLC was completed.

Intellectual Property

Each author has stated that they do not have direct, personal knowledge of any IPR related to this document. I am not aware of any IPR discussion about this document on the CoRE WG.

Other Points

There are RFC Editor comments that need to be edited out. The document creates two new registries, a content type and various media types.

Checklist

• Does the shepherd stand behind the document and think the document is ready for publication?
• Is the correct RFC type indicated in the title page header?
• Is the abstract both brief and sufficient, and does it stand alone as a brief summary?
• Is the intent of the document accurately and adequately explained in the introduction?
• Have all required formal reviews (MIB Doctor, Media Type, URI, etc.) been requested and/or completed?
• Has the shepherd performed automated checks – idnits (see http://www.ietf.org/tools/idnits/ and the Internet-Drafts Checklist), checks of BNF rules, XML code and schemas, MIB definitions, and so on – and determined that the document passes the tests?
• Has each author stated that their direct, personal knowledge of any IPR related to this document has already been disclosed, in conformance with BCPs 78 and 79?
• Have all references within this document been identified as either normative or informative, and does the shepherd agree with how they have been classified?
• Are all normative references made to documents that are ready for advancement and are otherwise in a clear state?
• If publication of this document changes the status of any existing RFCs, are those RFCs listed on the title page header, and are the changes listed in the abstract and discussed (explained, not just mentioned) in the introduction? Does not apply

• If this is a bis document, have all of the errata been considered? Does not apply

• IANA Considerations:

  • Are the IANA Considerations clear and complete? Remember that IANA have to understand unambiguously what’s being requested, so they can perform the required actions. Q: Are the new media type IDs assigned sequentially or do we request something concrete to IANA? URL to check http://www.iana.org/assignments/core-parameters/core-parameters.xhtml A: I think a sequence of 8 values starting from a round number (for easy mnemonic) would make sense. But could check with the experts what's the policy here

  • Are all protocol extensions that the document makes associated with the appropriate reservations in IANA registries?

  • Are all IANA registries referred to by their exact names (check them in http://www.iana.org/protocols/ to be sure)?

  • Have you checked that any registrations made by this document correctly follow the policies and procedures for the appropriate registries?I believe so, double check with Carsten on the new registries.

  • For registrations that require expert review (policies of Expert Review or Specification Required), have you or the working group had any early review done, to make sure the requests are ready for last call?

  • For any new registries that this document creates, has the working group actively chosen the allocation procedures and policies and discussed the alternatives?

  • Have reasonable registry names been chosen (that will not be confused with those of other registries), and have the initial contents and valid value ranges been clearly specified?