draft-ietf-core-senml-versions-00.txt   draft-ietf-core-senml-versions-01.txt 
Network Working Group C. Bormann Network Working Group C. Bormann
Internet-Draft Universitaet Bremen TZI Internet-Draft Universitaet Bremen TZI
Updates: 8428 (if approved) 13 May 2020 Updates: 8428 (if approved) 15 November 2020
Intended status: Standards Track Intended status: Standards Track
Expires: 14 November 2020 Expires: 19 May 2021
SenML Features and Versions SenML Features and Versions
draft-ietf-core-senml-versions-00 draft-ietf-core-senml-versions-01
Abstract Abstract
This short document updates RFC 8428, Sensor Measurement Lists This short document updates RFC 8428, Sensor Measurement Lists
(SenML), by specifying the use of independently selectable "SenML (SenML), by specifying the use of independently selectable "SenML
Features" and mapping them to SenML version numbers. Features" and mapping them to SenML version numbers.
Discussion Venues
This note is to be removed before publishing as an RFC.
Discussion of this document takes place on the CORE Working Group
mailing list (core@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/core/
(https://mailarchive.ietf.org/arch/browse/core/).
Source for this draft and an issue tracker can be found at
https://github.com/core-wg/senml-versions (https://github.com/core-
wg/senml-versions).
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on 14 November 2020. This Internet-Draft will expire on 19 May 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Feature Codes and the Version number . . . . . . . . . . . . 2 2. Feature Codes and the Version number . . . . . . . . . . . . 3
3. Features: Reserved0, Reserved1, Reserved2, Reserved3 . . . . 3 3. Features: Reserved0, Reserved1, Reserved2, Reserved3 . . . . 3
4. Feature: Secondary Units . . . . . . . . . . . . . . . . . . 3 4. Feature: Secondary Units . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 3 5. Security Considerations . . . . . . . . . . . . . . . . . . . 4
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
7. Normative References . . . . . . . . . . . . . . . . . . . . 4 7. Normative References . . . . . . . . . . . . . . . . . . . . 5
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 5 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 5
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction 1. Introduction
The Sensor Measurement Lists (SenML) specification [RFC8428] provides The Sensor Measurement Lists (SenML) specification [RFC8428] provides
a version number that is initially set to 10, without further a version number that is initially set to 10, without further
specification on the way to make use of different version numbers. specification on the way to make use of different version numbers.
The traditional idea of using a version number for evolving an The traditional idea of using a version number for evolving an
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This short document specifies the use of SenML Features and maps them This short document specifies the use of SenML Features and maps them
to SenML version number space, updating [RFC8428]. to SenML version number space, updating [RFC8428].
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
Where bit arithmetic is explained, this document uses the notation Where bit arithmetic is explained, this document uses the notation
familiar from the programming language C, except that "**" denotes familiar from the programming language C [C], except that superscript
exponentiation. notation (example for two to the power of 64: 2^(64)) denotes
exponentiation; in the plain text version of this draft, superscript
notation is rendered by C-incompatible surrogate notation as seen in
this example.
2. Feature Codes and the Version number 2. Feature Codes and the Version number
The present specification defines "SenML Features", each identified The present specification defines "SenML Features", each identified
by a "feature name" (a text string) and a "feature code", an unsigned by a "feature name" (a text string) and a "feature code", an unsigned
integer less than 53. integer less than 53.
The specific version of a SenML pack is composed of a set of The specific version of a SenML pack is composed of a set of
features. The SenML version number ("bver" field) is then a bitmap features. The SenML version number ("bver" field) is then a bitmap
of these features, specifically the sum of, for each feature present, of these features, specifically the sum of, for each feature present,
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to 3 are already in use. Reserved1 (1) and Reserved3 (3) are always to 3 are already in use. Reserved1 (1) and Reserved3 (3) are always
present and the features Reserved0 (0) and Reserved2 (2) are always present and the features Reserved0 (0) and Reserved2 (2) are always
absent, yielding a version number of 10 if no other feature is in absent, yielding a version number of 10 if no other feature is in
use. These four reserved feature codes are not to be used with any use. These four reserved feature codes are not to be used with any
more specific semantics except in a specification that updates the more specific semantics except in a specification that updates the
present specification. present specification.
4. Feature: Secondary Units 4. Feature: Secondary Units
The feature "Secondary Units" (code number 4) indicates that The feature "Secondary Units" (code number 4) indicates that
secondary unit names [I-D.ietf-core-senml-more-units] MAY be be used secondary unit names [RFC8798] MAY be be used in the "u" field of
in the "u" field of SenML Records, in addition to the primary unit SenML Records, in addition to the primary unit names already allowed
names already allowed by [RFC8428]. by [RFC8428].
Note that the most basic use of this feature simply sets the SenML Note that the most basic use of this feature simply sets the SenML
version number to 26 (10 + 2**4). version number to 26 (10 + 2^(4)).
5. Security Considerations 5. Security Considerations
The security considerations of [RFC8428] apply. This specification The security considerations of [RFC8428] apply. This specification
provides structure to the interpretation of the SenML version number, provides structure to the interpretation of the SenML version number,
which poses no additional security considerations except for some which poses no additional security considerations except for some
potential for surprise that version numbers do not simply increase potential for surprise that version numbers do not simply increase
linearly. linearly.
6. IANA Considerations 6. IANA Considerations
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potential for surprise that version numbers do not simply increase potential for surprise that version numbers do not simply increase
linearly. linearly.
6. IANA Considerations 6. IANA Considerations
IANA is requested to create a new subregistry "SenML features" within IANA is requested to create a new subregistry "SenML features" within
the SenML registry [IANA.senml], with the registration policy the SenML registry [IANA.senml], with the registration policy
"specification required" [RFC8126] and the columns: "specification required" [RFC8126] and the columns:
* Feature code (an unsigned integer less than 53) * Feature code (an unsigned integer less than 53)
* Feature name (text) * Feature name (text)
* Specification * Specification
The initial content of this registry is as follows: The initial content of this registry is as follows:
+--------------+-----------------+---------------+ +==============+=================+===============+
| Feature code | Feature name | Specification | | Feature code | Feature name | Specification |
+==============+=================+===============+ +==============+=================+===============+
| 0 | Reserved0 | RFCthis | | 0 | Reserved0 | RFCthis |
+--------------+-----------------+---------------+ +--------------+-----------------+---------------+
| 1 | Reserved1 | RFCthis | | 1 | Reserved1 | RFCthis |
+--------------+-----------------+---------------+ +--------------+-----------------+---------------+
| 2 | Reserved2 | RFCthis | | 2 | Reserved2 | RFCthis |
+--------------+-----------------+---------------+ +--------------+-----------------+---------------+
| 3 | Reserved3 | RFCthis | | 3 | Reserved3 | RFCthis |
+--------------+-----------------+---------------+ +--------------+-----------------+---------------+
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As the number of features that can be registered has a hard limit (48 As the number of features that can be registered has a hard limit (48
codes left at the time of writing), the designated expert is codes left at the time of writing), the designated expert is
specifically instructed to maintain a frugal regime of code point specifically instructed to maintain a frugal regime of code point
allocation, keeping code points available for SenML Features that are allocation, keeping code points available for SenML Features that are
likely to be useful for non-trivial subsets of the SenML ecosystem. likely to be useful for non-trivial subsets of the SenML ecosystem.
Quantitatively, the expert could for instance steer the allocation to Quantitatively, the expert could for instance steer the allocation to
not allocate more than 10 % of the remaining set per year. not allocate more than 10 % of the remaining set per year.
7. Normative References 7. Normative References
[I-D.ietf-core-senml-more-units] [C] International Organization for Standardization,
Bormann, C., "Additional Units for SenML", Work in "Information technology — Programming languages — C", ISO/
Progress, Internet-Draft, draft-ietf-core-senml-more- IEC 9899:2018, Fourth Edition, June 2018.
units-06, 19 March 2020, <http://www.ietf.org/internet-
drafts/draft-ietf-core-senml-more-units-06.txt>.
[IANA.senml] [IANA.senml]
IANA, "Sensor Measurement Lists (SenML)", IANA, "Sensor Measurement Lists (SenML)",
<http://www.iana.org/assignments/senml>. <http://www.iana.org/assignments/senml>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
skipping to change at page 5, line 19 skipping to change at page 5, line 42
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>. May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8428] Jennings, C., Shelby, Z., Arkko, J., Keranen, A., and C. [RFC8428] Jennings, C., Shelby, Z., Arkko, J., Keranen, A., and C.
Bormann, "Sensor Measurement Lists (SenML)", RFC 8428, Bormann, "Sensor Measurement Lists (SenML)", RFC 8428,
DOI 10.17487/RFC8428, August 2018, DOI 10.17487/RFC8428, August 2018,
<https://www.rfc-editor.org/info/rfc8428>. <https://www.rfc-editor.org/info/rfc8428>.
[RFC8798] Bormann, C., "Additional Units for Sensor Measurement
Lists (SenML)", RFC 8798, DOI 10.17487/RFC8798, June 2020,
<https://www.rfc-editor.org/info/rfc8798>.
Acknowledgements Acknowledgements
Ari Keranen proposed to use the version number as a bitmap and Ari Keranen proposed to use the version number as a bitmap and
provided further input on this specification. provided further input on this specification.
Author's Address Author's Address
Carsten Bormann Carsten Bormann
Universitaet Bremen TZI Universitaet Bremen TZI
Postfach 330440 Postfach 330440
D-28359 Bremen D-28359 Bremen
Germany Germany
Phone: +49-421-218-63921 Phone: +49-421-218-63921
Email: cabo@tzi.org Email: cabo@tzi.org
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