draft-ietf-core-senml-16.txt   rfc8428.txt 
Network Working Group C. Jennings Internet Engineering Task Force (IETF) C. Jennings
Internet-Draft Cisco Request for Comments: 8428 Cisco
Intended status: Standards Track Z. Shelby Category: Standards Track Z. Shelby
Expires: November 19, 2018 ARM ISSN: 2070-1721 ARM
J. Arkko J. Arkko
A. Keranen A. Keranen
Ericsson Ericsson
C. Bormann C. Bormann
Universitaet Bremen TZI Universitaet Bremen TZI
May 18, 2018 August 2018
Sensor Measurement Lists (SenML) Sensor Measurement Lists (SenML)
draft-ietf-core-senml-16
Abstract Abstract
This specification defines a format for representing simple sensor This specification defines a format for representing simple sensor
measurements and device parameters in the Sensor Measurement Lists measurements and device parameters in Sensor Measurement Lists
(SenML). Representations are defined in JavaScript Object Notation (SenML). Representations are defined in JavaScript Object Notation
(JSON), Concise Binary Object Representation (CBOR), Extensible (JSON), Concise Binary Object Representation (CBOR), Extensible
Markup Language (XML), and Efficient XML Interchange (EXI), which Markup Language (XML), and Efficient XML Interchange (EXI), which
share the common SenML data model. A simple sensor, such as a share the common SenML data model. A simple sensor, such as a
temperature sensor, could use one of these media types in protocols temperature sensor, could use one of these media types in protocols
such as HTTP or CoAP to transport the measurements of the sensor or such as HTTP or the Constrained Application Protocol (CoAP) to
to be configured. transport the measurements of the sensor or to be configured.
Status of This Memo Status of This Memo
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provisions of BCP 78 and BCP 79.
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Copyright Notice Copyright Notice
Copyright (c) 2018 IETF Trust and the persons identified as the Copyright (c) 2018 IETF Trust and the persons identified as the
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Table of Contents Table of Contents
1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Overview . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Requirements and Design Goals . . . . . . . . . . . . . . . . 4 2. Requirements and Design Goals . . . . . . . . . . . . . . . . 4
3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
4. SenML Structure and Semantics . . . . . . . . . . . . . . . . 6 4. SenML Structure and Semantics . . . . . . . . . . . . . . . . 6
4.1. Base Fields . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Base Fields . . . . . . . . . . . . . . . . . . . . . . . 7
4.2. Regular Fields . . . . . . . . . . . . . . . . . . . . . 7 4.2. Regular Fields . . . . . . . . . . . . . . . . . . . . . 7
4.3. SenML Labels . . . . . . . . . . . . . . . . . . . . . . 8 4.3. SenML Labels . . . . . . . . . . . . . . . . . . . . . . 8
4.4. Extensibility . . . . . . . . . . . . . . . . . . . . . . 8 4.4. Extensibility . . . . . . . . . . . . . . . . . . . . . . 9
4.5. Records and Their Fields . . . . . . . . . . . . . . . . 9 4.5. Records and Their Fields . . . . . . . . . . . . . . . . 9
4.5.1. Names . . . . . . . . . . . . . . . . . . . . . . . . 9 4.5.1. Names . . . . . . . . . . . . . . . . . . . . . . . . 9
4.5.2. Units . . . . . . . . . . . . . . . . . . . . . . . . 9 4.5.2. Units . . . . . . . . . . . . . . . . . . . . . . . . 10
4.5.3. Time . . . . . . . . . . . . . . . . . . . . . . . . 10 4.5.3. Time . . . . . . . . . . . . . . . . . . . . . . . . 10
4.5.4. Values . . . . . . . . . . . . . . . . . . . . . . . 11 4.5.4. Values . . . . . . . . . . . . . . . . . . . . . . . 11
4.6. Resolved Records . . . . . . . . . . . . . . . . . . . . 11 4.6. Resolved Records . . . . . . . . . . . . . . . . . . . . 12
4.7. Associating Meta-data . . . . . . . . . . . . . . . . . . 12 4.7. Associating Metadata . . . . . . . . . . . . . . . . . . 12
4.8. Sensor Streaming Measurement Lists (SensML) . . . . . . . 12 4.8. Sensor Streaming Measurement Lists (SenSML) . . . . . . . 12
4.9. Configuration and Actuation usage . . . . . . . . . . . . 12 4.9. Configuration and Actuation Usage . . . . . . . . . . . . 13
5. JSON Representation (application/senml+json) . . . . . . . . 13 5. JSON Representation (application/senml+json) . . . . . . . . 13
5.1. Examples . . . . . . . . . . . . . . . . . . . . . . . . 14 5.1. Examples . . . . . . . . . . . . . . . . . . . . . . . . 14
5.1.1. Single Datapoint . . . . . . . . . . . . . . . . . . 14 5.1.1. Single Data Point . . . . . . . . . . . . . . . . . . 14
5.1.2. Multiple Datapoints . . . . . . . . . . . . . . . . . 14 5.1.2. Multiple Data Points . . . . . . . . . . . . . . . . 14
5.1.3. Multiple Measurements . . . . . . . . . . . . . . . . 15 5.1.3. Multiple Measurements . . . . . . . . . . . . . . . . 15
5.1.4. Resolved Data . . . . . . . . . . . . . . . . . . . . 16 5.1.4. Resolved Data . . . . . . . . . . . . . . . . . . . . 17
5.1.5. Multiple Data Types . . . . . . . . . . . . . . . . . 17 5.1.5. Multiple Data Types . . . . . . . . . . . . . . . . . 17
5.1.6. Collection of Resources . . . . . . . . . . . . . . . 17 5.1.6. Collection of Resources . . . . . . . . . . . . . . . 18
5.1.7. Setting an Actuator . . . . . . . . . . . . . . . . . 17 5.1.7. Setting an Actuator . . . . . . . . . . . . . . . . . 18
6. CBOR Representation (application/senml+cbor) . . . . . . . . 18 6. CBOR Representation (application/senml+cbor) . . . . . . . . 19
7. XML Representation (application/senml+xml) . . . . . . . . . 20 7. XML Representation (application/senml+xml) . . . . . . . . . 21
8. EXI Representation (application/senml-exi) . . . . . . . . . 22 8. EXI Representation (application/senml-exi) . . . . . . . . . 23
9. Fragment Identification Methods . . . . . . . . . . . . . . . 25 9. Fragment Identification Methods . . . . . . . . . . . . . . . 26
9.1. Fragment Identification Examples . . . . . . . . . . . . 25 9.1. Fragment Identification Examples . . . . . . . . . . . . 26
9.2. Fragment Identification for the XML and EXI Formats . . . 26 9.2. Fragment Identification for XML and EXI Formats . . . . . 27
10. Usage Considerations . . . . . . . . . . . . . . . . . . . . 26 10. Usage Considerations . . . . . . . . . . . . . . . . . . . . 27
11. CDDL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 11. CDDL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 29 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 30
12.1. Units Registry . . . . . . . . . . . . . . . . . . . . . 29 12.1. SenML Units Registry . . . . . . . . . . . . . . . . . . 30
12.2. SenML Label Registry . . . . . . . . . . . . . . . . . . 33 12.2. SenML Labels Registry . . . . . . . . . . . . . . . . . 35
12.3. Media Type Registrations . . . . . . . . . . . . . . . . 34 12.3. Media Type Registrations . . . . . . . . . . . . . . . . 36
12.3.1. senml+json Media Type Registration . . . . . . . . . 35 12.3.1. senml+json Media Type Registration . . . . . . . . . 37
12.3.2. sensml+json Media Type Registration . . . . . . . . 36 12.3.2. sensml+json Media Type Registration . . . . . . . . 38
12.3.3. senml+cbor Media Type Registration . . . . . . . . . 37 12.3.3. senml+cbor Media Type Registration . . . . . . . . . 39
12.3.4. sensml+cbor Media Type Registration . . . . . . . . 38 12.3.4. sensml+cbor Media Type Registration . . . . . . . . 41
12.3.5. senml+xml Media Type Registration . . . . . . . . . 39 12.3.5. senml+xml Media Type Registration . . . . . . . . . 42
12.3.6. sensml+xml Media Type Registration . . . . . . . . . 41 12.3.6. sensml+xml Media Type Registration . . . . . . . . . 43
12.3.7. senml-exi Media Type Registration . . . . . . . . . 42 12.3.7. senml-exi Media Type Registration . . . . . . . . . 44
12.3.8. sensml-exi Media Type Registration . . . . . . . . . 43 12.3.8. sensml-exi Media Type Registration . . . . . . . . . 45
12.4. XML Namespace Registration . . . . . . . . . . . . . . . 44 12.4. XML Namespace Registration . . . . . . . . . . . . . . . 47
12.5. CoAP Content-Format Registration . . . . . . . . . . . . 44 12.5. CoAP Content-Format Registration . . . . . . . . . . . . 47
13. Security Considerations . . . . . . . . . . . . . . . . . . . 45 13. Security Considerations . . . . . . . . . . . . . . . . . . . 47
14. Privacy Considerations . . . . . . . . . . . . . . . . . . . 46 14. Privacy Considerations . . . . . . . . . . . . . . . . . . . 48
15. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 46 15. References . . . . . . . . . . . . . . . . . . . . . . . . . 49
16. References . . . . . . . . . . . . . . . . . . . . . . . . . 46 15.1. Normative References . . . . . . . . . . . . . . . . . . 49
16.1. Normative References . . . . . . . . . . . . . . . . . . 46 15.2. Informative References . . . . . . . . . . . . . . . . . 51
16.2. Informative References . . . . . . . . . . . . . . . . . 49 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 53
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 51 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 54
1. Overview 1. Overview
Connecting sensors to the Internet is not new, and there have been Connecting sensors to the Internet is not new, and there have been
many protocols designed to facilitate it. This specification defines many protocols designed to facilitate it. This specification defines
a format and media types for carrying simple sensor information in a a format and media types for carrying simple sensor information in
protocol such as HTTP [RFC7230] or CoAP [RFC7252]. The SenML format protocols such as HTTP [RFC7230] or CoAP [RFC7252]. The SenML format
is designed so that processors with very limited capabilities could is designed so that processors with very limited capabilities could
easily encode a sensor measurement into the media type, while at the easily encode a sensor measurement into the media type, while at the
same time a server parsing the data could relatively efficiently same time, a server parsing the data could collect a large number of
collect a large number of sensor measurements. SenML can be used for sensor measurements in a relatively efficient manner. SenML can be
a variety of data flow models, most notably data feeds pushed from a used for a variety of data flow models, most notably data feeds
sensor to a collector, and the web resource model where the sensor is pushed from a sensor to a collector, and for the web resource model
requested as a resource representation (e.g., "GET /sensor/ where the sensor data is requested as a resource representation
temperature"). (e.g., "GET /sensor/temperature").
There are many types of more complex measurements and measurements There are many types of more complex measurements and measurements
that this media type would not be suitable for. SenML strikes a that this media type would not be suitable for. SenML strikes a
balance between having some information about the sensor carried with balance between having some information about the sensor carried with
the sensor data so that the data is self describing but it also tries the sensor data so that the data is self-describing, but it also
to make that a fairly minimal set of auxiliary information for tries to make that a fairly minimal set of auxiliary information for
efficiency reason. Other information about the sensor can be efficiency reasons. Other information about the sensor can be
discovered by other methods such as using the CoRE Link Format discovered by other methods such as using the Constrained RESTful
[RFC6690]. Environments (CoRE) Link Format [RFC6690].
SenML is defined by a data model for measurements and simple meta- SenML is defined by a data model for measurements and simple metadata
data about measurements and devices. The data is structured as a about measurements and devices. The data is structured as a single
single array that contains a series of SenML Records which can each array that contains a series of SenML Records that can each contain
contain fields such as an unique identifier for the sensor, the time fields such as a unique identifier for the sensor, the time the
the measurement was made, the unit the measurement is in, and the measurement was made, the unit the measurement is in, and the current
current value of the sensor. Serializations for this data model are value of the sensor. Serializations for this data model are defined
defined for JSON [RFC8259], CBOR [RFC7049], XML for JSON [RFC8259], CBOR [RFC7049], XML [W3C.REC-xml-20081126], and
[W3C.REC-xml-20081126], and Efficient XML Interchange (EXI) Efficient XML Interchange (EXI) [W3C.REC-exi-20140211].
[W3C.REC-exi-20140211].
For example, the following shows a measurement from a temperature For example, the following shows a measurement from a temperature
gauge encoded in the JSON syntax. gauge encoded in the JSON syntax.
[ [
{"n":"urn:dev:ow:10e2073a01080063","u":"Cel","v":23.1} {"n":"urn:dev:ow:10e2073a01080063","u":"Cel","v":23.1}
] ]
In the example above, the array has a single SenML Record with a In the example above, the array has a single SenML Record with a
measurement for a sensor named "urn:dev:ow:10e2073a01080063" with a measurement for a sensor named "urn:dev:ow:10e2073a01080063" with a
current value of 23.1 degrees Celsius. current value of 23.1 degrees Celsius.
2. Requirements and Design Goals 2. Requirements and Design Goals
The design goal is to be able to send simple sensor measurements in The design goal is to be able to send simple sensor measurements in
small packets from large numbers of constrained devices. Keeping the small packets from large numbers of constrained devices. Keeping the
total size of payload small makes it easy to use SenML also in total size of the payload small makes it easy to also use SenML in
constrained networks, e.g., in a 6LoWPAN [RFC4944]. It is always constrained networks, e.g., in an IPv6 over Low-Power Wireless
difficult to define what small code is, but there is a desire to be Personal Area Network (6LoWPAN) [RFC4944]. It is always difficult to
able to implement this in roughly 1 KB of flash on a 8 bit define what small code is, but there is a desire to be able to
microprocessor. Experience with power meters and other large scale implement this in roughly 1 KB of flash on an 8-bit microprocessor.
deployments has indicated that the solution needs to support allowing Experience with power meters and other large-scale deployments has
multiple measurements to be batched into a single HTTP or CoAP indicated that the solution needs to support allowing multiple
request. This "batch" upload capability allows the server side to measurements to be batched into a single HTTP or CoAP request. This
efficiently support a large number of devices. It also conveniently "batch" upload capability allows the server side to efficiently
supports batch transfers from proxies and storage devices, even in support a large number of devices. It also conveniently supports
situations where the sensor itself sends just a single data item at a batch transfers from proxies and storage devices, even in situations
time. The multiple measurements could be from multiple related where the sensor itself sends just a single data item at a time. The
sensors or from the same sensor but at different times. multiple measurements could be from multiple related sensors or from
the same sensor but at different times.
The basic design is an array with a series of measurements. The The basic design is an array with a series of measurements. The
following example shows two measurements made at different times. following example shows two measurements made at different times.
The value of a measurement is given by the "v" field, the time of a The value of a measurement is given by the "v" field, the time of a
measurement is in the "t" field, the "n" field has a unique sensor measurement is in the "t" field, the "n" field has a unique sensor
name, and the unit of the measurement is carried in the "u" field. name, and the unit of the measurement is carried in the "u" field.
[ [
{"n":"urn:dev:ow:10e2073a01080063","u":"Cel","t":1.276020076e+09, {"n":"urn:dev:ow:10e2073a01080063","u":"Cel","t":1.276020076e+09,
"v":23.5}, "v":23.5},
{"n":"urn:dev:ow:10e2073a01080063","u":"Cel","t":1.276020091e+09, {"n":"urn:dev:ow:10e2073a01080063","u":"Cel","t":1.276020091e+09,
"v":23.6} "v":23.6}
] ]
To keep the messages small, it does not make sense to repeat the "n" To keep the messages small, it does not make sense to repeat the "n"
field in each SenML Record so there is a concept of a Base Name which field in each SenML Record, so there is a concept of a Base Name,
is simply a string that is prepended to the Name field of all which is simply a string that is prepended to the Name field of all
elements in that record and any records that follow it. So a more elements in that Record and any Records that follow it. So, a more
compact form of the example above is the following. compact form of the example above is the following.
[ [
{"bn":"urn:dev:ow:10e2073a01080063","u":"Cel","t":1.276020076e+09, {"bn":"urn:dev:ow:10e2073a01080063","u":"Cel","t":1.276020076e+09,
"v":23.5}, "v":23.5},
{"u":"Cel","t":1.276020091e+09, {"u":"Cel","t":1.276020091e+09,
"v":23.6} "v":23.6}
] ]
In the above example the Base Name is in the "bn" field and the "n" In the above example, the Base Name is in the "bn" field, and the "n"
fields in each Record are the empty string so they are omitted. fields in each Record are empty strings, so they are omitted.
Some devices have accurate time while others do not so SenML supports Some devices have accurate time while others do not, so SenML
absolute and relative times. Time is represented in floating point supports absolute and relative times. Time is represented in
as seconds. Values greater than or equal to 2**28 represent an floating point as seconds. Values greater than or equal to 2**28
absolute time relative to the Unix epoch. Values less than 2**28 represent an absolute time relative to the Unix epoch. Values less
represent time relative to the current time. than 2**28 represent time relative to the current time.
A simple sensor with no absolute wall clock time might take a A simple sensor with no absolute wall-clock time might take a
measurement every second, batch up 60 of them, and then send the measurement every second, batch up 60 of them, and then send the
batch to a server. It would include the relative time each batch to a server. It would include the relative time each
measurement was made compared to the time the batch was sent in each measurement was made compared to the time the batch was sent in each
SenML Record. The server might have accurate NTP time and use the SenML Record. If the server has accurate time based on, e.g., the
time it received the data, and the relative offset, to replace the Network Time Protocol (NTP), it may use the time it received the data
times in the SenML with absolute times before saving the SenML and the relative offset to replace the times in the SenML with
information in a document database. absolute times before saving the SenML information in a document
database.
3. Terminology 3. Terminology
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 BCP "OPTIONAL" in this document are to be interpreted as described in
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.
This document also uses the following terms: This document also uses the following terms:
SenML Record: One measurement or configuration instance in time SenML Record: One measurement or configuration instance in time
presented using the SenML data model. presented using the SenML data model.
SenML Pack: One or more SenML Records in an array structure. SenML Pack: One or more SenML Records in an array structure.
SenML Label: A short name used in SenML Records to denote different SenML Label: A short name used in SenML Records to denote different
SenML fields (e.g., "v" for "value"). SenML fields (e.g., "v" for "value").
SenML Field: A component of a record that associates a value to a SenML Field: A component of a record that associates a value to a
SenML Label for this record. SenML Label for this record.
SensML: Sensor Streaming Measurement List (see Section 4.8). SenSML: Sensor Streaming Measurement List (see Section 4.8).
SensML Stream: One or more SenML Records to be processed as a SenSML Stream: One or more SenML Records to be processed as a
stream. stream.
This document uses the terms "attribute" and "tag" where they occur This document uses the terms "attribute" and "tag" where they occur
with the underlying technologies (XML, CBOR [RFC7049], and Link with the underlying technologies (XML, CBOR [RFC7049], and the CoRE
Format [RFC6690]), not for SenML concepts per se. Note that Link Format [RFC6690]); they are not used for SenML concepts, per se.
"attribute" has been widely used previously as a synonym for SenML However, note that "attribute" has been widely used in the past as a
"field", though. synonym for the SenML "field".
All comparisons of text strings are performed byte-by-byte (and All comparisons of text strings are performed byte by byte, which
therefore necessarily case-sensitive). results in the comparisons being case sensitive.
Where arithmetic is used, this specification uses the notation Where arithmetic is used, this specification uses the familiar
familiar from the programming language C, except that the operator notation of the programming language C, except that the operator "**"
"**" stands for exponentiation. stands for exponentiation.
4. SenML Structure and Semantics 4. SenML Structure and Semantics
Each SenML Pack carries a single array that represents a set of Each SenML Pack carries a single array that represents a set of
measurements and/or parameters. This array contains a series of measurements and/or parameters. This array contains a series of
SenML Records with several fields described below. There are two SenML Records with several fields described below. There are two
kinds of fields: base and regular. Both the base fields and the kinds of fields: base and regular. Both the base and regular fields
regular fields can be included in any SenML Record. The base fields can be included in any SenML Record. The base fields apply to the
apply to the entries in the Record and also to all Records after it entries in the Record and also to all Records after it up to, but not
up to, but not including, the next Record that has that same base including, the next Record that has that same base field. All base
field. All base fields are optional. Regular fields can be included fields are optional. Regular fields can be included in any SenML
in any SenML Record and apply only to that Record. Record and apply only to that Record.
4.1. Base Fields 4.1. Base Fields
Base Name: This is a string that is prepended to the names found in Base Name: This is a string that is prepended to the names found in
the entries. the entries.
Base Time: A base time that is added to the time found in an entry. Base Time: A base time that is added to the time found in an entry.
Base Unit: A base unit that is assumed for all entries, unless Base Unit: A base unit that is assumed for all entries, unless
otherwise indicated. If a record does not contain a Unit value, otherwise indicated. If a record does not contain a Unit value,
then the Base Unit is used. Otherwise the value found in the Unit then the Base Unit is used. Otherwise, the value found in the
(if any) is used. Unit (if any) is used.
Base Value: A base value is added to the value found in an entry, Base Value: A base value is added to the value found in an entry,
similar to Base Time. similar to Base Time.
Base Sum: A base sum is added to the sum found in an entry, similar Base Sum: A base sum is added to the sum found in an entry, similar
to Base Time. to Base Time.
Version: Version number of media type format. This field is an Base Version: Version number of the media type format. This field
optional positive integer and defaults to 5 if not present. [RFC is an optional positive integer and defaults to 10 if not present.
Editor: change the default value to 10 when this specification is
published as an RFC and remove this note]
4.2. Regular Fields 4.2. Regular Fields
Name: Name of the sensor or parameter. When appended to the Base Name: Name of the sensor or parameter. When appended to the Base
Name field, this must result in a globally unique identifier for Name field, this must result in a globally unique identifier for
the resource. The name is optional, if the Base Name is present. the resource. The name is optional, if the Base Name is present.
If the name is missing, Base Name must uniquely identify the If the name is missing, the Base Name must uniquely identify the
resource. This can be used to represent a large array of resource. This can be used to represent a large array of
measurements from the same sensor without having to repeat its measurements from the same sensor without having to repeat its
identifier on every measurement. identifier on every measurement.
Unit: Unit for a measurement value. Optional. Unit: Unit for a measurement value. Optional.
Value: Value of the entry. Optional if a Sum value is present, Value: Value of the entry. Optional if a Sum value is present;
otherwise required. Values are represented using basic data otherwise, it's required. Values are represented using basic data
types. This specification defines floating point numbers ("v" types. This specification defines floating-point numbers ("v"
field for "Value"), booleans ("vb" for "Boolean Value"), strings field for "Value"), booleans ("vb" for "Boolean Value"), strings
("vs" for "String Value") and binary data ("vd" for "Data Value"). ("vs" for "String Value"), and binary data ("vd" for "Data
Exactly one value field MUST appear unless there is Sum field in Value"). Exactly one Value field MUST appear unless there is a
which case it is allowed to have no Value field. Sum field, in which case it is allowed to have no Value field.
Sum: Integrated sum of the values over time. Optional. This field Sum: Integrated sum of the values over time. Optional. This field
is in the unit specified in the Unit value multiplied by seconds. is in the unit specified in the Unit value multiplied by seconds.
For historical reason it is named sum instead of integral. For historical reasons, it is named "sum" instead of "integral".
Time: Time when value was recorded. Optional. Time: Time when the value was recorded. Optional.
Update Time: Period of time in seconds that represents the maximum Update Time: Period of time in seconds that represents the maximum
time before this sensor will provide an updated reading for a time before this sensor will provide an updated reading for a
measurement. Optional. This can be used to detect the failure of measurement. Optional. This can be used to detect the failure of
sensors or communications path from the sensor. sensors or the communications path from the sensor.
4.3. SenML Labels 4.3. SenML Labels
Table 1 provides an overview of all SenML fields defined by this Table 1 provides an overview of all SenML fields defined by this
document with their respective labels and data types. document with their respective labels and data types.
+---------------+-------+------------+------------+------------+ +---------------+-------+------------+------------+------------+
| Name | Label | CBOR Label | JSON Type | XML Type | | Name | Label | CBOR Label | JSON Type | XML Type |
+---------------+-------+------------+------------+------------+ +---------------+-------+------------+------------+------------+
| Base Name | bn | -2 | String | string | | Base Name | bn | -2 | String | string |
| Base Time | bt | -3 | Number | double | | Base Time | bt | -3 | Number | double |
| Base Unit | bu | -4 | String | string | | Base Unit | bu | -4 | String | string |
| Base Value | bv | -5 | Number | double | | Base Value | bv | -5 | Number | double |
| Base Sum | bs | -6 | Number | double | | Base Sum | bs | -6 | Number | double |
| Version | bver | -1 | Number | int | | Base Version | bver | -1 | Number | int |
| Name | n | 0 | String | string | | Name | n | 0 | String | string |
| Unit | u | 1 | String | string | | Unit | u | 1 | String | string |
| Value | v | 2 | Number | double | | Value | v | 2 | Number | double |
| String Value | vs | 3 | String | string | | String Value | vs | 3 | String | string |
| Boolean Value | vb | 4 | Boolean | boolean | | Boolean Value | vb | 4 | Boolean | boolean |
| Data Value | vd | 8 | String (*) | string (*) | | Data Value | vd | 8 | String (*) | string (*) |
| Value Sum | s | 5 | Number | double | | Sum | s | 5 | Number | double |
| Time | t | 6 | Number | double | | Time | t | 6 | Number | double |
| Update Time | ut | 7 | Number | double | | Update Time | ut | 7 | Number | double |
+---------------+-------+------------+------------+------------+ +---------------+-------+------------+------------+------------+
Table 1: SenML Labels Table 1: SenML Labels
(*) Data Value is base64 encoded string with URL safe alphabet as (*) Data Value is a base64-encoded string with the URL-safe alphabet
defined in Section 5 of [RFC4648], with padding omitted. as defined in Section 5 of [RFC4648], with padding omitted. (In
CBOR, the octets in the Data Value are encoded using a definite-
length byte string, major type 2.)
For details of the JSON representation see Section 5, for the CBOR For details of the JSON representation, see Section 5; for CBOR, see
Section 6, and for the XML Section 7. Section 6; and for XML, see Section 7.
4.4. Extensibility 4.4. Extensibility
The SenML format can be extended with further custom fields. Both The SenML format can be extended with further custom fields. Both
new base and regular fields are allowed. See Section 12.2 for new base and regular fields are allowed. See Section 12.2 for
details. Implementations MUST ignore fields they don't recognize details. Implementations MUST ignore fields they don't recognize
unless that field has a label name that ends with the '_' character unless that field has a label name that ends with the "_" character,
in which case an error MUST be generated. in which case an error MUST be generated.
All SenML Records in a Pack MUST have the same version number. This All SenML Records in a Pack MUST have the same version number. This
is typically done by adding a Base Version field to only the first is typically done by adding a Base Version field to only the first
Record in the Pack, or by using the default value. Record in the Pack or by using the default value.
Systems reading one of the objects MUST check for the Version field. Systems reading one of the objects MUST check for the Base Version
If this value is a version number larger than the version which the field. If this value is a version number larger than the version
system understands, the system MUST NOT use this object. This allows that the system understands, the system MUST NOT use this object.
the version number to indicate that the object contains structure or This allows the version number to indicate that the object contains
semantics that is different from what is defined in the present structure or semantics that is different from what is defined in the
document beyond just making use of the extension points provided present document beyond just making use of the extension points
here. New version numbers can only be defined in an RFC that updates provided here. New version numbers can only be defined in an RFC
this specification or it successors. that updates this specification or its successors.
4.5. Records and Their Fields 4.5. Records and Their Fields
4.5.1. Names 4.5.1. Names
The Name value is concatenated to the Base Name value to yield the The Name value is concatenated to the Base Name value to yield the
name of the sensor. The resulting concatenated name needs to name of the sensor. The resulting concatenated name needs to
uniquely identify and differentiate the sensor from all others. The uniquely identify and differentiate the sensor from all others. The
concatenated name MUST consist only of characters out of the set "A" concatenated name MUST consist only of characters out of the set "A"
to "Z", "a" to "z", "0" to "9", "-", ":", ".", "/", and "_"; to "Z", "a" to "z", and "0" to "9", as well as "-", ":", ".", "/",
furthermore, it MUST start with a character out of the set "A" to and "_"; furthermore, it MUST start with a character out of the set
"Z", "a" to "z", or "0" to "9". This restricted character set was "A" to "Z", "a" to "z", or "0" to "9". This restricted character set
chosen so that concatenated names can be used directly within various was chosen so that concatenated names can be used directly within
URI schemes (including segments of an HTTP path with no special various URI schemes (including segments of an HTTP path with no
encoding; note that a name that contains "/" characters maps into special encoding; note that a name that contains "/" characters maps
multiple URI path segments) and can be used directly in many into multiple URI path segments) and can be used directly in many
databases and analytic systems. [RFC5952] contains advice on databases and analytic systems. [RFC5952] contains advice on
encoding an IPv6 address in a name. See Section 14 for privacy encoding an IPv6 address in a name. See Section 14 for privacy
considerations that apply to the use of long-term stable unique considerations that apply to the use of long-term stable unique
identifiers. identifiers.
Although it is RECOMMENDED that concatenated names are represented as Although it is RECOMMENDED that concatenated names be represented as
URIs [RFC3986] or URNs [RFC8141], the restricted character set URIs [RFC3986] or URNs [RFC8141], the restricted character set
specified above puts strict limits on the URI schemes and URN specified above puts strict limits on the URI schemes and URN
namespaces that can be used. As a result, implementers need to take namespaces that can be used. As a result, implementers need to take
care in choosing the naming scheme for concatenated names, because care in choosing the naming scheme for concatenated names, because
such names both need to be unique and need to conform to the such names both need to be unique and need to conform to the
restricted character set. One approach is to include a bit string restricted character set. One approach is to include a bit string
that has guaranteed uniqueness (such as a 1-wire address [AN1796]). that has guaranteed uniqueness (such as a 1-wire address [AN1796]).
Some of the examples within this document use the device URN Some of the examples within this document use the device URN
namespace as specified in [I-D.ietf-core-dev-urn]. UUIDs [RFC4122] namespace as specified in [DEVICE-URN]. Universally Unique
are another way to generate a unique name. However, the restricted Identifiers (UUIDs) [RFC4122] are another way to generate a unique
character set does not allow the use of many URI schemes, such as the name. However, the restricted character set does not allow the use
'tag' scheme [RFC4151] and the 'ni' scheme [RFC6920], in names as of many URI schemes, such as the "tag" scheme [RFC4151] and the "ni"
such. The use of URIs with characters incompatible with this set, scheme [RFC6920], in names as such. The use of URIs with characters
and possible mapping rules between the two, are outside of the scope incompatible with this set and possible mapping rules between the two
of the present document. are outside the scope of the present document.
4.5.2. Units 4.5.2. Units
If the Record has no Unit, the Base Unit is used as the Unit. Having If the Record has no Unit, the Base Unit is used as the Unit. Having
no Unit and no Base Unit is allowed; any information that may be no Unit and no Base Unit is allowed; any information that may be
required about units applicable to the value then needs to be required about units applicable to the value then needs to be
provided by the application context. provided by the application context.
4.5.3. Time 4.5.3. Time
If either the Base Time or Time value is missing, the missing field If either the Base Time or Time value is missing, the missing field
is considered to have a value of zero. The Base Time and Time values is considered to have a value of zero. The Base Time and Time values
are added together to get the time of measurement. are added together to get a value representing the time of
measurement.
Values less than 268,435,456 (2**28) represent time relative to the Values less than 268,435,456 (2**28) represent time relative to the
current time. That is, a time of zero indicates that the sensor does current time. That is, a time of zero indicates that the sensor does
not know the absolute time and the measurement was made roughly not know the absolute time and the measurement was made roughly
"now". A negative value indicates seconds in the past from roughly "now". A negative value indicates seconds in the past from roughly
"now". Positive values up to 2**28 indicate seconds in the future "now". Positive values up to 2**28 indicate seconds in the future
from "now". Positive values can be used, e.g., for actuation use from "now". An example for employing positive values would be
when the desired change should happen in the future but the sender or actuation use, when the desired change should happen in the future,
the receiver does not have accurate time available. but the sender or the receiver does not have accurate time available.
Values greater than or equal to 2**28 represent an absolute time Values greater than or equal to 2**28 represent an absolute time
relative to the Unix epoch (1970-01-01T00:00Z in UTC time) and the relative to the Unix epoch (1970-01-01T00:00Z in UTC time), and the
time is counted same way as the Portable Operating System Interface time is counted the same way as the Portable Operating System
(POSIX) "seconds since the epoch" [TIME_T]. Therefore the smallest Interface (POSIX) "seconds since the epoch" [TIME_T]. Therefore, the
absolute time value that can be expressed (2**28) is 1978-07-04 smallest absolute Time value that can be expressed (2**28) is
21:24:16 UTC. 1978-07-04 21:24:16 UTC.
Because time values up to 2**28 are used for presenting time relative Because Time values up to 2**28 are used for representing time
to "now" and Time and Base Time are added together, care must be relative to "now" and Time and Base Time are added together, care
taken to ensure that the sum does not inadvertently reach 2**28 must be taken to ensure that the sum does not inadvertently reach
(i.e., absolute time) when relative time was intended to be used. 2**28 (i.e., absolute time) when relative time was intended to be
used.
Obviously, "now"-referenced SenML records are only useful within a Obviously, SenML Records referenced to "now" are only useful within a
specific communication context (e.g., based on information on when specific communication context (e.g., based on information on when
the SenML pack, or a specific record in a SensML stream, was sent) or the SenML Pack, or a specific Record in a SenSML Stream, was sent) or
together with some other context information that can be used for together with some other context information that can be used for
deriving a meaning of "now"; the expectation for any archival use is deriving a meaning of "now"; the expectation for any archival use is
that they will be processed into UTC-referenced records before that that they will be processed into UTC-referenced records before that
context would cease to be available. This specification deliberately context would cease to be available. This specification deliberately
leaves the accuracy of "now" very vague as it is determined by the leaves the accuracy of "now" very vague as it is determined by the
overall systems that use SenML. In a system where a sensor without overall systems that use SenML. In a system where a sensor without
wall-clock time sends a SenML record with a "now"-referenced time wall-clock time sends a SenML Record with a time referenced to "now"
over a high speed RS 485 link to an embedded system with accurate over a high-speed RS-485 link to an embedded system with accurate
time that resolves "now" based on the time of reception, the time that resolves "now" based on the time of reception, the
resulting time uncertainty could be within 1 ms. At the other resulting time uncertainty could be within 1 ms. At the other
extreme, a deployment that sends SenML wind speed readings over a LEO extreme, a deployment that sends SenML wind-speed readings over a
satellite link from a mountain valley might have resulting reception Low-Earth Orbit (LEO) satellite link from a mountain valley might
time values that are easily a dozen minutes off the actual time of have resulting reception Time values that are easily a dozen minutes
the sensor reading, with the time uncertainty depending on satellite off the actual time of the sensor reading, with the time uncertainty
locations and conditions. depending on satellite locations and conditions.
4.5.4. Values 4.5.4. Values
If only one of the Base Sum or Sum value is present, the missing If only one of the Base Sum or Sum value is present, the missing
field is considered to have a value of zero. The Base Sum and Sum field is considered to have a value of zero. The Base Sum and Sum
values are added together to get the sum of measurement. If neither values are added together to get the sum of measurement. If neither
the Base Sum or Sum are present, then the measurement does not have a the Base Sum nor the Sum is present, then the measurement does not
sum value. have a Sum value.
If the Base Value or Value is not present, the missing field(s) are If the Base Value or Value is not present, the missing field(s) is
considered to have a value of zero. The Base Value and Value are considered to have a value of zero. The Base Value and Value are
added together to get the value of the measurement. added together to get the value of the measurement.
Representing the statistical characteristics of measurements, such as Representing the statistical characteristics of measurements, such as
accuracy, can be very complex. Future specification may add new accuracy, can be very complex. Future specification may add new
fields to provide better information about the statistical properties fields to provide better information about the statistical properties
of the measurement. of the measurement.
In summary, the structure of a SenML record is laid out to support a In summary, the structure of a SenML Record is laid out to support a
single measurement per record. If multiple data values are measured single measurement per Record. If multiple data values are measured
at the same time (e.g., air pressure and altitude), they are best at the same time (e.g., air pressure and altitude), they are best
kept as separate records linked through their Time value; this is kept as separate Records linked through their Time value; this is
even true where one of the data values is more "meta" than others even true when one of the data values is more "meta" than others
(e.g., describes a condition that influences other measurements at (e.g., describes a condition that influences other measurements at
the same time). the same time).
4.6. Resolved Records 4.6. Resolved Records
Sometimes it is useful to be able to refer to a defined normalized Sometimes it is useful to be able to refer to a defined normalized
format for SenML records. This normalized format tends to get used format for SenML Records. This normalized format tends to get used
for big data applications and intermediate forms when converting to for big data applications and intermediate forms when converting to
other formats. Also, if SenML Records are used outside of a SenML other formats. Also, if SenML Records are used outside of a SenML
Pack, they need to be resolved first to ensure applicable base values Pack, they need to be resolved first to ensure applicable base values
are applied. are applied.
A SenML Record is referred to as "resolved" if it does not contain A SenML Record is referred to as "resolved" if it does not contain
any base values, i.e., labels starting with the character 'b', except any base values, i.e., labels starting with the character "b", except
for Version fields (see below), and has no relative times. To for Base Version fields (see below), and has no relative times. To
resolve the Records, the applicable base values of the SenML Pack (if resolve the Records, the applicable base values of the SenML Pack (if
any) are applied to the Record. That is, for the base values in the any) are applied to the Record. That is, for the base values in the
Record or before the Record in the Pack, name and base name are Record or before the Record in the Pack, Name and Base Name are
concatenated, base time is added to the time of the Record, if the concatenated, the Base Time is added to the time of the Record, the
Record did not contain Unit the Base Unit is applied to the record, Base Unit is applied to the Record if it did not contain a Unit, etc.
etc. In addition the records need to be in chronological order in In addition, the Records need to be in chronological order in the
the Pack. An example of this is shown in Section 5.1.4. Pack. An example of this is shown in Section 5.1.4.
The Version field MUST NOT be present in resolved records if the The Base Version field MUST NOT be present in resolved Records if the
SenML version defined in this document is used and MUST be present SenML version defined in this document is used; otherwise, it MUST be
otherwise in all the resolved SenML Records. present in all the resolved SenML Records.
Future specification that defines new base fields need to specify how A future specification that defines new base fields needs to specify
the field is resolved. how the field is resolved.
4.7. Associating Meta-data 4.7. Associating Metadata
SenML is designed to carry the minimum dynamic information about SenML is designed to carry the minimum dynamic information about
measurements, and for efficiency reasons does not carry significant measurements and, for efficiency reasons, does not carry significant
static meta-data about the device, object or sensors. Instead, it is static metadata about the device, object, or sensors. Instead, it is
assumed that this meta-data is carried out of band. For web assumed that this metadata is carried out of band. For web resources
resources using SenML Packs, this meta-data can be made available using SenML Packs, this metadata can be made available using the CoRE
using the CoRE Link Format [RFC6690]. The most obvious use of this Link Format [RFC6690]. The most obvious use of this link format is
link format is to describe that a resource is available in a SenML to describe that a resource is available in a SenML format in the
format in the first place. The relevant media type indicator is first place. The relevant media type indicator is included in the
included in the Content-Type (ct=) link attribute (which is defined Content-Type (ct=) link attribute (which is defined for the link
for the Link Format in Section 7.2.1 of [RFC7252]). format in Section 7.2.1 of [RFC7252]).
4.8. Sensor Streaming Measurement Lists (SensML) 4.8. Sensor Streaming Measurement Lists (SenSML)
In some usage scenarios of SenML, the implementations store or In some usage scenarios of SenML, the implementations store or
transmit SenML in a stream-like fashion, where data is collected over transmit SenML in a stream-like fashion, where data is collected over
time and continuously added to the object. This mode of operation is time and continuously added to the object. This mode of operation is
optional, but systems or protocols using SenML in this fashion MUST optional, but systems or protocols using SenML in this fashion MUST
specify that they are doing this. SenML defines separate media types specify that they are doing this. SenML defines separate media types
to indicate Sensor Streaming Measurement Lists (SensML) for this to indicate Sensor Streaming Measurement Lists (SenSML) for this
usage (see Section 12.3.2). In this situation, the SensML stream can usage (see Section 12.3.2). In this situation, the SenSML Stream can
be sent and received in a partial fashion, i.e., a measurement entry be sent and received in a partial fashion, i.e., a measurement entry
can be read as soon as the SenML Record is received and does not have can be read as soon as the SenML Record is received and does not have
to wait for the full SensML Stream to be complete. to wait for the full SenSML Stream to be complete.
If times relative to "now" (see Section 4.5.3) are used in SenML If times relative to "now" (see Section 4.5.3) are used in SenML
Records of a SensML stream, their interpretation of "now" is based on Records of a SenSML Stream, their interpretation of "now" is based on
the time when the specific Record is sent in the stream. the time when the specific Record is sent in the stream.
4.9. Configuration and Actuation usage 4.9. Configuration and Actuation Usage
SenML can also be used for configuring parameters and controlling SenML can also be used for configuring parameters and controlling
actuators. When a SenML Pack is sent (e.g., using a HTTP/CoAP POST actuators. When a SenML Pack is sent (e.g., using an HTTP/CoAP POST
or PUT method) and the semantics of the target are such that SenML is or PUT method) and the semantics of the target are such that SenML is
interpreted as configuration/actuation, SenML Records are interpreted interpreted as configuration/actuation, SenML Records are interpreted
as a request to change the values of given (sub)resources (given as as a request to change the values of given (sub)resources (given as
names) to given values at the given time(s). The semantics of the names) to given values at the given time(s). The semantics of the
target resource supporting this usage can be described, e.g., using target resource supporting this usage can be described, e.g., using
[I-D.ietf-core-interfaces]. Examples of actuation usage are shown in [RID-CoRE]. Examples of actuation usage are shown in Section 5.1.7.
Section 5.1.7.
5. JSON Representation (application/senml+json) 5. JSON Representation (application/senml+json)
For the SenML fields shown in Table 2, the SenML labels are used as For the SenML fields shown in Table 2, the SenML Labels are used as
the JSON object member names within JSON objects representing the the JSON object member names within JSON objects representing the
JSON SenML Records. JSON SenML Records.
+---------------+-------+---------+ +---------------+-------+-----------+
| Name | label | Type | | Name | Label | JSON Type |
+---------------+-------+---------+ +---------------+-------+-----------+
| Base Name | bn | String | | Base Name | bn | String |
| Base Time | bt | Number | | Base Time | bt | Number |
| Base Unit | bu | String | | Base Unit | bu | String |
| Base Value | bv | Number | | Base Value | bv | Number |
| Base Sum | bs | Number | | Base Sum | bs | Number |
| Version | bver | Number | | Base Version | bver | Number |
| Name | n | String | | Name | n | String |
| Unit | u | String | | Unit | u | String |
| Value | v | Number | | Value | v | Number |
| String Value | vs | String | | String Value | vs | String |
| Boolean Value | vb | Boolean | | Boolean Value | vb | Boolean |
| Data Value | vd | String | | Data Value | vd | String |
| Value Sum | s | Number | | Sum | s | Number |
| Time | t | Number | | Time | t | Number |
| Update Time | ut | Number | | Update Time | ut | Number |
+---------------+-------+---------+ +---------------+-------+-----------+
Table 2: JSON SenML Labels Table 2: JSON SenML Labels
The root JSON value consists of an array with one JSON object for The root JSON value consists of an array with one JSON object for
each SenML Record. All the fields in the above table MAY occur in each SenML Record. All the fields in the above table MAY occur in
the records with member values of the type specified in the table. the Records with member values of the type specified in the table.
Only the UTF-8 [RFC3629] form of JSON is allowed. Characters in the Only the UTF-8 [RFC3629] form of JSON is allowed. Characters in the
String Value are encoded using the escape sequences defined in String Value are encoded using the escape sequences defined in
[RFC8259]. Octets in the Data Value are base64 encoded with URL safe [RFC8259]. Octets in the Data Value are base64 encoded with the URL-
alphabet as defined in Section 5 of [RFC4648], with padding omitted. safe alphabet as defined in Section 5 of [RFC4648], with padding
omitted.
Systems receiving measurements MUST be able to process the range of Systems receiving measurements MUST be able to process the range of
floating point numbers that are representable as an IEEE double floating-point numbers that are representable as IEEE double-
precision floating point numbers [IEEE.754.1985]. This allows time precision, floating-point numbers [IEEE.754]. This allows Time
values to have better than microsecond precision over the next 100 values to have better than microsecond precision over the next 100
years. The number of significant digits in any measurement is not years. The number of significant digits in any measurement is not
relevant, so a reading of 1.1 has exactly the same semantic meaning relevant, so a reading of 1.1 has exactly the same semantic meaning
as 1.10. If the value has an exponent, the "e" MUST be in lower as 1.10. If the value has an exponent, the "e" MUST be in lower
case. In the interest of avoiding unnecessary verbosity and speeding case. In the interest of avoiding unnecessary verbosity and speeding
up processing, the mantissa SHOULD be less than 19 characters long up processing, the mantissa SHOULD be less than 19 characters long,
and the exponent SHOULD be less than 5 characters long. and the exponent SHOULD be less than 5 characters long.
5.1. Examples 5.1. Examples
5.1.1. Single Datapoint 5.1.1. Single Data Point
The following shows a temperature reading taken approximately "now" The following shows a temperature reading taken approximately "now"
by a 1-wire sensor device that was assigned the unique 1-wire address by a 1-wire sensor device that was assigned the unique 1-wire address
of 10e2073a01080063: of 10e2073a01080063:
[ [
{"n":"urn:dev:ow:10e2073a01080063","u":"Cel","v":23.1} {"n":"urn:dev:ow:10e2073a01080063","u":"Cel","v":23.1}
] ]
5.1.2. Multiple Datapoints 5.1.2. Multiple Data Points
The following example shows voltage and current now, i.e., at an The following example shows voltage and current "now", i.e., at an
unspecified time. unspecified time.
[ [
{"bn":"urn:dev:ow:10e2073a01080063:","n":"voltage","u":"V","v":120.1}, {"bn":"urn:dev:ow:10e2073a01080063:","n":"voltage","u":"V","v":120.1},
{"n":"current","u":"A","v":1.2} {"n":"current","u":"A","v":1.2}
] ]
The next example is similar to the above one, but it shows current at
The next example is similar to the above one, but shows current at
Tue Jun 8 18:01:16.001 UTC 2010 and at each second for the previous 5 Tue Jun 8 18:01:16.001 UTC 2010 and at each second for the previous 5
seconds. seconds.
[ [
{"bn":"urn:dev:ow:10e2073a0108006:","bt":1.276020076001e+09, {"bn":"urn:dev:ow:10e2073a0108006:","bt":1.276020076001e+09,
"bu":"A","bver":5, "bu":"A","bver":5,
"n":"voltage","u":"V","v":120.1}, "n":"voltage","u":"V","v":120.1},
{"n":"current","t":-5,"v":1.2}, {"n":"current","t":-5,"v":1.2},
{"n":"current","t":-4,"v":1.3}, {"n":"current","t":-4,"v":1.3},
{"n":"current","t":-3,"v":1.4}, {"n":"current","t":-3,"v":1.4},
{"n":"current","t":-2,"v":1.5}, {"n":"current","t":-2,"v":1.5},
{"n":"current","t":-1,"v":1.6}, {"n":"current","t":-1,"v":1.6},
{"n":"current","v":1.7} {"n":"current","v":1.7}
] ]
As an example of Sensor Streaming Measurement Lists (SensML), the As an example of SenSML, the following stream of measurements may be
following stream of measurements may be sent via a long lived HTTP sent via a long-lived HTTP POST from the producer of the stream to
POST from the producer of the stream to its consumer, and each its consumer, and each measurement object may be reported at the time
measurement object may be reported at the time it was measured: it was measured:
[ [
{"bn":"urn:dev:ow:10e2073a01080063","bt":1.320067464e+09, {"bn":"urn:dev:ow:10e2073a01080063","bt":1.320067464e+09,
"bu":"%RH","v":21.2}, "bu":"%RH","v":21.2},
{"t":10,"v":21.3}, {"t":10,"v":21.3},
{"t":20,"v":21.4}, {"t":20,"v":21.4},
{"t":30,"v":21.4}, {"t":30,"v":21.4},
{"t":40,"v":21.5}, {"t":40,"v":21.5},
{"t":50,"v":21.5}, {"t":50,"v":21.5},
{"t":60,"v":21.5}, {"t":60,"v":21.5},
{"t":70,"v":21.6}, {"t":70,"v":21.6},
{"t":80,"v":21.7}, {"t":80,"v":21.7},
... ...
5.1.3. Multiple Measurements 5.1.3. Multiple Measurements
The following example shows humidity measurements from a mobile The following example shows humidity measurements from a mobile
device with a 1-wire address 10e2073a01080063, starting at Mon Oct 31 device with a 1-wire address 10e2073a01080063, starting at Mon Oct 31
13:24:24 UTC 2011. The device also provides position data, which is 13:24:24 UTC 2011. The device also provides position data, which is
provided in the same measurement or parameter array as separate provided in the same measurement or parameter array as separate
entries. Note time is used to for correlating data that belongs entries. Note that time is used to correlate data that belongs
together, e.g., a measurement and a parameter associated with it. together, e.g., a measurement and a parameter associated with it.
Finally, the device also reports extra data about its battery status Finally, the device also reports extra data about its battery status
at a separate time. at a separate time.
[ [
{"bn":"urn:dev:ow:10e2073a01080063","bt":1.320067464e+09, {"bn":"urn:dev:ow:10e2073a01080063","bt":1.320067464e+09,
"bu":"%RH","v":20}, "bu":"%RH","v":20},
{"u":"lon","v":24.30621}, {"u":"lon","v":24.30621},
{"u":"lat","v":60.07965}, {"u":"lat","v":60.07965},
{"t":60,"v":20.3}, {"t":60,"v":20.3},
skipping to change at page 15, line 46 skipping to change at page 16, line 22
{"u":"lat","t":60,"v":60.07965}, {"u":"lat","t":60,"v":60.07965},
{"t":120,"v":20.7}, {"t":120,"v":20.7},
{"u":"lon","t":120,"v":24.30623}, {"u":"lon","t":120,"v":24.30623},
{"u":"lat","t":120,"v":60.07966}, {"u":"lat","t":120,"v":60.07966},
{"u":"%EL","t":150,"v":98}, {"u":"%EL","t":150,"v":98},
{"t":180,"v":21.2}, {"t":180,"v":21.2},
{"u":"lon","t":180,"v":24.30628}, {"u":"lon","t":180,"v":24.30628},
{"u":"lat","t":180,"v":60.07967} {"u":"lat","t":180,"v":60.07967}
] ]
The size of this example represented in various forms, as well as The following table shows the size of this example in various forms,
that form compressed with gzip is given in the following table. as well as the size of each of these forms compressed with gzip.
+----------+------+-----------------+ +----------+------+-----------------+
| Encoding | Size | Compressed Size | | Encoding | Size | Compressed Size |
+----------+------+-----------------+ +----------+------+-----------------+
| JSON | 573 | 206 | | JSON | 573 | 206 |
| XML | 649 | 235 | | XML | 649 | 235 |
| CBOR | 254 | 196 | | CBOR | 254 | 196 |
| EXI | 161 | 184 | | EXI | 161 | 184 |
+----------+------+-----------------+ +----------+------+-----------------+
Table 3: Size Comparisons Table 3: Size Comparisons
5.1.4. Resolved Data 5.1.4. Resolved Data
The following shows the example from the previous section show in The following shows the example from the previous section in resolved
resolved format. format.
[ [
{"n":"urn:dev:ow:10e2073a01080063","u":"%RH","t":1.320067464e+09, {"n":"urn:dev:ow:10e2073a01080063","u":"%RH","t":1.320067464e+09,
"v":20}, "v":20},
{"n":"urn:dev:ow:10e2073a01080063","u":"lon","t":1.320067464e+09, {"n":"urn:dev:ow:10e2073a01080063","u":"lon","t":1.320067464e+09,
"v":24.30621}, "v":24.30621},
{"n":"urn:dev:ow:10e2073a01080063","u":"lat","t":1.320067464e+09, {"n":"urn:dev:ow:10e2073a01080063","u":"lat","t":1.320067464e+09,
"v":60.07965}, "v":60.07965},
{"n":"urn:dev:ow:10e2073a01080063","u":"%RH","t":1.320067524e+09, {"n":"urn:dev:ow:10e2073a01080063","u":"%RH","t":1.320067524e+09,
"v":20.3}, "v":20.3},
skipping to change at page 17, line 14 skipping to change at page 17, line 48
5.1.5. Multiple Data Types 5.1.5. Multiple Data Types
The following example shows a sensor that returns different data The following example shows a sensor that returns different data
types. types.
[ [
{"bn":"urn:dev:ow:10e2073a01080063:","n":"temp","u":"Cel","v":23.1}, {"bn":"urn:dev:ow:10e2073a01080063:","n":"temp","u":"Cel","v":23.1},
{"n":"label","vs":"Machine Room"}, {"n":"label","vs":"Machine Room"},
{"n":"open","vb":false}, {"n":"open","vb":false},
{"n":"nfv-reader","vd":"aGkgCg"} {"n":"nfc-reader","vd":"aGkgCg"}
] ]
5.1.6. Collection of Resources 5.1.6. Collection of Resources
The following example shows the results from a query to one device The following example shows the results from a query to one device
that aggregates multiple measurements from other devices. The that aggregates multiple measurements from other devices. The
example assumes that a client has fetched information from a device example assumes that a client has fetched information from a device
at 2001:db8::2 by performing a GET operation on http://[2001:db8::2] at 2001:db8::2 by performing a GET operation on http://[2001:db8::2]
at Mon Oct 31 16:27:09 UTC 2011, and has gotten two separate values at Mon Oct 31 16:27:09 UTC 2011 and has gotten two separate values as
as a result, a temperature and humidity measurement as well as the a result: a temperature and humidity measurement as well as the
results from another device at http://[2001:db8::1] that also had a results from another device at http://[2001:db8::1] that also had a
temperature and humidity. Note that the last record would use the temperature and humidity measurement. Note that the last record
Base Name from the 3rd record but the Base Time from the first would use the Base Name from the 3rd record but the Base Time from
record. the first record.
[ [
{"bn":"2001:db8::2/","bt":1.320078429e+09, {"bn":"2001:db8::2/","bt":1.320078429e+09,
"n":"temperature","u":"Cel","v":25.2}, "n":"temperature","u":"Cel","v":25.2},
{"n":"humidity","u":"%RH","v":30}, {"n":"humidity","u":"%RH","v":30},
{"bn":"2001:db8::1/","n":"temperature","u":"Cel","v":12.3}, {"bn":"2001:db8::1/","n":"temperature","u":"Cel","v":12.3},
{"n":"humidity","u":"%RH","v":67} {"n":"humidity","u":"%RH","v":67}
] ]
5.1.7. Setting an Actuator 5.1.7. Setting an Actuator
The following example show the SenML that could be used to set the The following example shows the SenML that could be used to set the
current set point of a typical residential thermostat which has a current set point of a typical residential thermostat that has a
temperature set point, a switch to turn on and off the heat, and a temperature set point, a switch to turn on and off the heat, and a
switch to turn on the fan override. switch to turn on the fan override.
[ [
{"bn":"urn:dev:ow:10e2073a01080063:"}, {"bn":"urn:dev:ow:10e2073a01080063:"},
{"n":"temp","u":"Cel","v":23.1}, {"n":"temp","u":"Cel","v":23.1},
{"n":"heat","u":"/","v":1}, {"n":"heat","u":"/","v":1},
{"n":"fan","u":"/","v":0} {"n":"fan","u":"/","v":0}
] ]
In the following example two different lights are turned on. It is
In the following example, two different lights are turned on. It is
assumed that the lights are on a network that can guarantee delivery assumed that the lights are on a network that can guarantee delivery
of the messages to the two lights within 15 ms (e.g. a network using of the messages to the two lights within 15 ms (e.g., a network using
802.1BA [IEEE802.1ba-2011] and 802.1AS [IEEE802.1as-2011] for time 802.1BA [IEEE802.1BA] and 802.1AS [IEEE802.1AS] for time
synchronization). The controller has set the time of the lights synchronization). The controller has set the time of the lights to
coming on to 20 ms in the future from the current time. This allows come on at 20 ms in the future from the current time. This allows
both lights to receive the message, wait till that time, then apply both lights to receive the message, wait till that time, then apply
the switch command so that both lights come on at the same time. the switch command so that both lights come on at the same time.
[ [
{"bt":1.320078429e+09,"bu":"/","n":"2001:db8::3","v":1}, {"bt":1.320078429e+09,"bu":"/","n":"2001:db8::3","v":1},
{"n":"2001:db8::4","v":1} {"n":"2001:db8::4","v":1}
] ]
The following shows two lights being turned off using a
The following shows two lights being turned off using a non non-deterministic network that has high odds of delivering a message
deterministic network that has a high odds of delivering a message in in less than 100 ms and uses NTP for time synchronization. The
less than 100 ms and uses NTP for time synchronization. The current current time is 1320078429. The user has just turned off a light
time is 1320078429. The user has just turned off a light switch switch that is turning off two lights. Both lights are immediately
which is turning off two lights. Both lights are dimmed to 50% dimmed to 50% brightness to give the user instant feedback that
brightness immediately to give the user instant feedback that something is changing. However, given the network, the lights will
something is changing. However given the network, the lights will
probably dim at somewhat different times. Then 100 ms in the future, probably dim at somewhat different times. Then 100 ms in the future,
both lights will go off at the same time. The instant but not both lights will go off at the same time. The instant, but not
synchronized dimming gives the user the sensation of quick responses synchronized, dimming gives the user the sensation of quick
and the timed off 100 ms in the future gives the perception of both responses, and the timed-off 100 ms in the future gives the
lights going off at the same time. perception of both lights going off at the same time.
[ [
{"bt":1.320078429e+09,"bu":"/","n":"2001:db8::3","v":0.5}, {"bt":1.320078429e+09,"bu":"/","n":"2001:db8::3","v":0.5},
{"n":"2001:db8::4","v":0.5}, {"n":"2001:db8::4","v":0.5},
{"n":"2001:db8::3","t":0.1,"v":0}, {"n":"2001:db8::3","t":0.1,"v":0},
{"n":"2001:db8::4","t":0.1,"v":0} {"n":"2001:db8::4","t":0.1,"v":0}
] ]
6. CBOR Representation (application/senml+cbor) 6. CBOR Representation (application/senml+cbor)
The CBOR [RFC7049] representation is equivalent to the JSON The CBOR [RFC7049] representation is equivalent to the JSON
representation, with the following changes: representation, with the following changes:
o For JSON Numbers, the CBOR representation can use integers, o For JSON Numbers, the CBOR representation can use integers,
floating point numbers, or decimal fractions (CBOR Tag 4); however floating-point numbers, or decimal fractions (CBOR Tag 4);
a representation SHOULD be chosen such that when the CBOR value is however, a representation SHOULD be chosen such that when the CBOR
converted back to an IEEE double precision floating point value, value is converted to an IEEE double-precision, floating-point
it has exactly the same value as the original Number. For the value, it has exactly the same value as the original JSON Number
version number, only an unsigned integer is allowed. converted to that form. For the version number, only an unsigned
integer is allowed.
o Characters in the String Value are encoded using a definite length o Characters in the String Value are encoded using a text string
text string (type 3). Octets in the Data Value are encoded using with a definite length (major type 3). Octets in the Data Value
a definite length byte string (type 2). are encoded using a byte string with a definite length (major type
2).
o For compactness, the CBOR representation uses integers for the o For compactness, the CBOR representation uses integers for the
labels, as defined in Table 4. This table is conclusive, i.e., labels, as defined in Table 4. This table is conclusive, i.e.,
there is no intention to define any additional integer map keys; there is no intention to define any additional integer map keys;
any extensions will use string map keys. This allows translators any extensions will use string map keys. This allows translators
converting between CBOR and JSON representations to convert also converting between CBOR and JSON representations to also convert
all future labels without needing to update implementations. The all future labels without needing to update implementations. Base
base values are given negative CBOR labels and others non-negative values are given negative CBOR labels, and others are given
labels. non-negative labels.
+---------------+-------+------------+ +---------------+-------+------------+
| Name | Label | CBOR Label | | Name | Label | CBOR Label |
+---------------+-------+------------+ +---------------+-------+------------+
| Version | bver | -1 | | Base Version | bver | -1 |
| Base Name | bn | -2 | | Base Name | bn | -2 |
| Base Time | bt | -3 | | Base Time | bt | -3 |
| Base Unit | bu | -4 | | Base Unit | bu | -4 |
| Base Value | bv | -5 | | Base Value | bv | -5 |
| Base Sum | bs | -6 | | Base Sum | bs | -6 |
| Name | n | 0 | | Name | n | 0 |
| Unit | u | 1 | | Unit | u | 1 |
| Value | v | 2 | | Value | v | 2 |
| String Value | vs | 3 | | String Value | vs | 3 |
| Boolean Value | vb | 4 | | Boolean Value | vb | 4 |
| Value Sum | s | 5 | | Sum | s | 5 |
| Time | t | 6 | | Time | t | 6 |
| Update Time | ut | 7 | | Update Time | ut | 7 |
| Data Value | vd | 8 | | Data Value | vd | 8 |
+---------------+-------+------------+ +---------------+-------+------------+
Table 4: CBOR representation: integers for map keys Table 4: CBOR Representation: Integers for Map Keys
o For streaming SensML in CBOR representation, the array containing o For streaming SenSML in CBOR representation, the array containing
the records SHOULD be a CBOR indefinite length array while for the records SHOULD be a CBOR array with an indefinite length; for
non-streaming SenML, a definite length array MUST be used. non-streaming SenML, an array with a definite length MUST be used.
The following example shows a dump of the CBOR example for the same The following example shows a dump of the CBOR example for the same
sensor measurement as in Section 5.1.2. sensor measurement as in Section 5.1.2.
0000 87 a7 21 78 1b 75 72 6e 3a 64 65 76 3a 6f 77 3a |..!x.urn:dev:ow:| 0000 87 a7 21 78 1b 75 72 6e 3a 64 65 76 3a 6f 77 3a |..!x.urn:dev:ow:|
0010 31 30 65 32 30 37 33 61 30 31 30 38 30 30 36 3a |10e2073a0108006:| 0010 31 30 65 32 30 37 33 61 30 31 30 38 30 30 36 3a |10e2073a0108006:|
0020 22 fb 41 d3 03 a1 5b 00 10 62 23 61 41 20 05 00 |".A...[..b#aA ..| 0020 22 fb 41 d3 03 a1 5b 00 10 62 23 61 41 20 05 00 |".A...[..b#aA ..|
0030 67 76 6f 6c 74 61 67 65 01 61 56 02 fb 40 5e 06 |gvoltage.aV..@^.| 0030 67 76 6f 6c 74 61 67 65 01 61 56 02 fb 40 5e 06 |gvoltage.aV..@^.|
0040 66 66 66 66 66 a3 00 67 63 75 72 72 65 6e 74 06 |fffff..gcurrent.| 0040 66 66 66 66 66 a3 00 67 63 75 72 72 65 6e 74 06 |fffff..gcurrent.|
0050 24 02 fb 3f f3 33 33 33 33 33 33 a3 00 67 63 75 |$..?.333333..gcu| 0050 24 02 fb 3f f3 33 33 33 33 33 33 a3 00 67 63 75 |$..?.333333..gcu|
skipping to change at page 20, line 33 skipping to change at page 21, line 17
-3: 1276020076.001, -4: "A", -1: 5, 0: "voltage", 1: "V", 2: 120.1}, -3: 1276020076.001, -4: "A", -1: 5, 0: "voltage", 1: "V", 2: 120.1},
{0: "current", 6: -5, 2: 1.2}, {0: "current", 6: -4, 2: 1.3}, {0: "current", 6: -5, 2: 1.2}, {0: "current", 6: -4, 2: 1.3},
{0: "current", 6: -3, 2: 1.4}, {0: "current", 6: -2, 2: 1.5}, {0: "current", 6: -3, 2: 1.4}, {0: "current", 6: -2, 2: 1.5},
{0: "current", 6: -1, 2: 1.6}, {0: "current", 6: 0, 2: 1.7}] {0: "current", 6: -1, 2: 1.6}, {0: "current", 6: 0, 2: 1.7}]
7. XML Representation (application/senml+xml) 7. XML Representation (application/senml+xml)
A SenML Pack or Stream can also be represented in XML format as A SenML Pack or Stream can also be represented in XML format as
defined in this section. defined in this section.
Only the UTF-8 form of XML is allowed. Characters in the String Only the UTF-8 form of XML is allowed. Octets in the Data Value are
Value are encoded using the escape sequences defined in [RFC8259]. base64 encoded with the URL-safe alphabet as defined in Section 5 of
Octets in the Data Value are base64 encoded with URL safe alphabet as [RFC4648], with padding omitted.
defined in Section 5 of [RFC4648].
The following example shows an XML example for the same sensor The following shows an XML example for the same sensor measurement as
measurement as in Section 5.1.2. in Section 5.1.2.
<sensml xmlns="urn:ietf:params:xml:ns:senml"> <sensml xmlns="urn:ietf:params:xml:ns:senml">
<senml bn="urn:dev:ow:10e2073a0108006:" bt="1.276020076001e+09" <senml bn="urn:dev:ow:10e2073a0108006:" bt="1.276020076001e+09"
bu="A" bver="5" n="voltage" u="V" v="120.1"></senml> bu="A" bver="5" n="voltage" u="V" v="120.1"></senml>
<senml n="current" t="-5" v="1.2"></senml> <senml n="current" t="-5" v="1.2"></senml>
<senml n="current" t="-4" v="1.3"></senml> <senml n="current" t="-4" v="1.3"></senml>
<senml n="current" t="-3" v="1.4"></senml> <senml n="current" t="-3" v="1.4"></senml>
<senml n="current" t="-2" v="1.5"></senml> <senml n="current" t="-2" v="1.5"></senml>
<senml n="current" t="-1" v="1.6"></senml> <senml n="current" t="-1" v="1.6"></senml>
<senml n="current" v="1.7"></senml> <senml n="current" v="1.7"></senml>
skipping to change at page 21, line 4 skipping to change at page 21, line 34
<sensml xmlns="urn:ietf:params:xml:ns:senml"> <sensml xmlns="urn:ietf:params:xml:ns:senml">
<senml bn="urn:dev:ow:10e2073a0108006:" bt="1.276020076001e+09" <senml bn="urn:dev:ow:10e2073a0108006:" bt="1.276020076001e+09"
bu="A" bver="5" n="voltage" u="V" v="120.1"></senml> bu="A" bver="5" n="voltage" u="V" v="120.1"></senml>
<senml n="current" t="-5" v="1.2"></senml> <senml n="current" t="-5" v="1.2"></senml>
<senml n="current" t="-4" v="1.3"></senml> <senml n="current" t="-4" v="1.3"></senml>
<senml n="current" t="-3" v="1.4"></senml> <senml n="current" t="-3" v="1.4"></senml>
<senml n="current" t="-2" v="1.5"></senml> <senml n="current" t="-2" v="1.5"></senml>
<senml n="current" t="-1" v="1.6"></senml> <senml n="current" t="-1" v="1.6"></senml>
<senml n="current" v="1.7"></senml> <senml n="current" v="1.7"></senml>
</sensml> </sensml>
The SenML Stream is represented as a sensml element that contains a The SenML Stream is represented as a sensml element that contains a
series of senml elements for each SenML Record. The SenML fields are series of senml elements for each SenML Record. The SenML fields are
represented as XML attributes. For each field defined in this represented as XML attributes. For each field defined in this
document, the following table shows the SenML labels, which are used document, the following table shows the SenML Labels, which are used
for the XML attribute name, as well as the according restrictions on for the XML attribute name, as well as the according restrictions on
the XML attribute values ("type") as used in the XML senml elements. the XML attribute values ("type") as used in the XML senml elements.
+---------------+-------+---------+ +---------------+-------+----------+
| Name | Label | Type | | Name | Label | XML Type |
+---------------+-------+---------+ +---------------+-------+----------+
| Base Name | bn | string | | Base Name | bn | string |
| Base Time | bt | double | | Base Time | bt | double |
| Base Unit | bu | string | | Base Unit | bu | string |
| Base Value | bv | double | | Base Value | bv | double |
| Base Sum | bs | double | | Base Sum | bs | double |
| Base Version | bver | int | | Base Version | bver | int |
| Name | n | string | | Name | n | string |
| Unit | u | string | | Unit | u | string |
| Value | v | double | | Value | v | double |
| String Value | vs | string | | String Value | vs | string |
| Data Value | vd | string | | Data Value | vd | string |
| Boolean Value | vb | boolean | | Boolean Value | vb | boolean |
| Value Sum | s | double | | Sum | s | double |
| Time | t | double | | Time | t | double |
| Update Time | ut | double | | Update Time | ut | double |
+---------------+-------+---------+ +---------------+-------+----------+
Table 5: XML SenML Labels Table 5: XML SenML Labels
The RelaxNG [RNC] schema for the XML is: The RelaxNG [RNC] Schema for the XML is:
default namespace = "urn:ietf:params:xml:ns:senml" default namespace = "urn:ietf:params:xml:ns:senml"
namespace rng = "http://relaxng.org/ns/structure/1.0" namespace rng = "http://relaxng.org/ns/structure/1.0"
senml = element senml { senml = element senml {
attribute bn { xsd:string }?, attribute bn { xsd:string }?,
attribute bt { xsd:double }?, attribute bt { xsd:double }?,
attribute bv { xsd:double }?, attribute bv { xsd:double }?,
attribute bs { xsd:double }?, attribute bs { xsd:double }?,
attribute bu { xsd:string }?, attribute bu { xsd:string }?,
skipping to change at page 22, line 27 skipping to change at page 23, line 4
attribute s { xsd:double }?, attribute s { xsd:double }?,
attribute t { xsd:double }?, attribute t { xsd:double }?,
attribute u { xsd:string }?, attribute u { xsd:string }?,
attribute ut { xsd:double }?, attribute ut { xsd:double }?,
attribute v { xsd:double }?, attribute v { xsd:double }?,
attribute vb { xsd:boolean }?, attribute vb { xsd:boolean }?,
attribute vs { xsd:string }?, attribute vs { xsd:string }?,
attribute vd { xsd:string }? attribute vd { xsd:string }?
} }
sensml = sensml =
element sensml { element sensml {
senml+ senml+
} }
start = sensml start = sensml
8. EXI Representation (application/senml-exi) 8. EXI Representation (application/senml-exi)
For efficient transmission of SenML over e.g. a constrained network, For efficient transmission of SenML over, e.g., a constrained
Efficient XML Interchange (EXI) can be used. This encodes the XML network, EXI can be used. This encodes the XML Schema
Schema [W3C.REC-xmlschema-1-20041028] structure of SenML into binary [W3C.REC-xmlschema-1-20041028] structure of SenML into binary tags
tags and values rather than ASCII text. An EXI representation of and values rather than ASCII text. An EXI representation of SenML
SenML SHOULD be made using the strict schema-mode of EXI. This mode SHOULD be made using the strict schema mode of EXI. However, this
however does not allow tag extensions to the schema, and therefore mode does not allow tag extensions to the schema; therefore, any
any extensions will be lost in the encoding. For uses where extensions will be lost in the encoding. For uses where extensions
extensions need to be preserved in EXI, the non-strict schema mode of need to be preserved in EXI, the non-strict schema mode of EXI MAY be
EXI MAY be used. used.
The EXI header MUST include an "EXI Options", as defined in The EXI header MUST include "EXI Options", as defined in
[W3C.REC-exi-20140211], with an schemaId set to the value of "a" [W3C.REC-exi-20140211], with a schemaId set to the value of "a",
indicating the schema provided in this specification. Future indicating the schema provided in this specification. Future
revisions to the schema can change the value of the schemaId to allow revisions to the schema can change the value of the schemaId to allow
for backwards compatibility. When the data will be transported over for backwards compatibility. When the data will be transported over
CoAP or HTTP, an EXI Cookie SHOULD NOT be used as it simply makes CoAP or HTTP, an EXI Cookie SHOULD NOT be used as it simply makes
things larger and is redundant to information provided in the things larger and is redundant to information provided in the
Content-Type header. Content-Type header.
The following is the XSD Schema to be used for strict schema guided The following is the XSD Schema to be used for strict schema-guided
EXI processing. It is generated from the RelaxNG. EXI processing. It is generated from the RelaxNG.
<?xml version="1.0" encoding="utf-8"?> <?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" <xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified" elementFormDefault="qualified"
targetNamespace="urn:ietf:params:xml:ns:senml" targetNamespace="urn:ietf:params:xml:ns:senml"
xmlns:ns1="urn:ietf:params:xml:ns:senml"> xmlns:ns1="urn:ietf:params:xml:ns:senml">
<xs:element name="senml"> <xs:element name="senml">
<xs:complexType> <xs:complexType>
<xs:attribute name="bn" type="xs:string" /> <xs:attribute name="bn" type="xs:string" />
skipping to change at page 23, line 44 skipping to change at page 24, line 42
<xs:element name="sensml"> <xs:element name="sensml">
<xs:complexType> <xs:complexType>
<xs:sequence> <xs:sequence>
<xs:element maxOccurs="unbounded" ref="ns1:senml" /> <xs:element maxOccurs="unbounded" ref="ns1:senml" />
</xs:sequence> </xs:sequence>
</xs:complexType> </xs:complexType>
</xs:element> </xs:element>
</xs:schema> </xs:schema>
The following shows a hexdump of the EXI produced from encoding the The following shows a hexdump of the EXI produced from encoding the
following XML example. Note this example is the same information as following XML example. Note that this example is the same
the first example in Section 5.1.2 in JSON format. information as the first example in Section 5.1.2 but in JSON format.
<sensml xmlns="urn:ietf:params:xml:ns:senml"> <sensml xmlns="urn:ietf:params:xml:ns:senml">
<senml bn="urn:dev:ow:10e2073a01080063:" n="voltage" u="V" <senml bn="urn:dev:ow:10e2073a01080063:" n="voltage" u="V"
v="120.1"></senml> v="120.1"></senml>
<senml n="current" u="A" v="1.2"></senml> <senml n="current" u="A" v="1.2"></senml>
</sensml> </sensml>
Which compresses with EXI to the following displayed in hexdump: Which compresses with EXI to the following displayed in hexdump:
0000 a0 30 0d 84 80 f3 ab 93 71 d3 23 2b b1 d3 7b b9 |.0......q.#+..{.| 0000 a0 30 0d 84 80 f3 ab 93 71 d3 23 2b b1 d3 7b b9 |.0......q.#+..{.|
0010 d1 89 83 29 91 81 b9 9b 09 81 89 81 c1 81 81 b1 |...)............| 0010 d1 89 83 29 91 81 b9 9b 09 81 89 81 c1 81 81 b1 |...)............|
0020 99 d2 84 bb 37 b6 3a 30 b3 b2 90 1a b1 58 84 c0 |....7.:0.....X..| 0020 99 d2 84 bb 37 b6 3a 30 b3 b2 90 1a b1 58 84 c0 |....7.:0.....X..|
0030 33 04 b1 ba b9 39 32 b7 3a 10 1a 09 06 40 38 |3....92.:....@8| 0030 33 04 b1 ba b9 39 32 b7 3a 10 1a 09 06 40 38 |3....92.:....@8|
003f 003f
The above example used the bit packed form of EXI but it is also The above example used the bit-packed form of EXI, but it is also
possible to use a byte packed form of EXI which can makes it easier possible to use a byte-packed form of EXI, which can make it easier
for a simple sensor to produce valid EXI without really implementing for a simple sensor to produce valid EXI without really implementing
EXI. Consider the example of a temperature sensor that produces a EXI. Consider the example of a temperature sensor that produces a
value in tenths of degrees Celsius over a range of 0.0 to 55.0. It value in tenths of degrees Celsius over a range of 0.0 to 55.0. It
would produce an XML SenML file such as: would produce an XML SenML file such as:
<sensml xmlns="urn:ietf:params:xml:ns:senml"> <sensml xmlns="urn:ietf:params:xml:ns:senml">
<senml n="urn:dev:ow:10e2073a01080063" u="Cel" v="23.1"></senml> <senml n="urn:dev:ow:10e2073a01080063" u="Cel" v="23.1"></senml>
</sensml> </sensml>
The compressed form, using the byte alignment option of EXI, for the The compressed form, using the byte-alignment option of EXI, for the
above XML is the following: above XML is the following:
0000 a0 00 48 80 6c 20 01 06 1d 75 72 6e 3a 64 65 76 |..H.l ...urn:dev| 0000 a0 00 48 80 6c 20 01 06 1d 75 72 6e 3a 64 65 76 |..H.l ...urn:dev|
0010 3a 6f 77 3a 31 30 65 32 30 37 33 61 30 31 30 38 |:ow:10e2073a0108| 0010 3a 6f 77 3a 31 30 65 32 30 37 33 61 30 31 30 38 |:ow:10e2073a0108|
0020 30 30 36 33 02 05 43 65 6c 01 00 e7 01 01 00 03 |0063..Cel.......| 0020 30 30 36 33 02 05 43 65 6c 01 00 e7 01 01 00 03 |0063..Cel.......|
0030 01 |.| 0030 01 |.|
0031 0031
A small temperature sensor device that only generates this one EXI A small temperature sensor device that only generates this one EXI
file does not really need a full EXI implementation. It can simply file does not really need a full EXI implementation. It can simply
hard code the output replacing the 1-wire device ID starting at byte hard code the output, replacing the 1-wire device ID starting at byte
0x14 and going to byte 0x23 with its device ID, and replacing the 0x14 and going to byte 0x23 with its device ID and replacing the
value "0xe7 0x01" at location 0x31 and 0x32 with the current value "0xe7 0x01" at location 0x2b and 0x2c with the current
temperature. The EXI Specification [W3C.REC-exi-20140211] contains temperature. The EXI specification [W3C.REC-exi-20140211] contains
the full information on how floating point numbers are represented, the full information on how floating-point numbers are represented,
but for the purpose of this sensor, the temperature can be converted but for the purpose of this sensor, the temperature can be converted
to an integer in tenths of degrees (231 in this example). EXI stores to an integer in tenths of degrees (231 in this example). EXI stores
7 bits of the integer in each byte with the top bit set to one if 7 bits of the integer in each byte with the top bit set to one if
there are further bytes. So the first bytes at is set to low 7 bits there are further bytes. So, the first byte is set to the low 7 bits
of the integer temperature in tenths of degrees plus 0x80. In this of the integer temperature in tenths of degrees plus 0x80. In this
example 231 & 0x7F + 0x80 = 0xE7. The second byte is set to the example, 231 & 0x7F + 0x80 = 0xE7. The second byte is set to the
integer temperature in tenths of degrees right shifted 7 bits. In integer temperature in tenths of degrees right-shifted 7 bits. In
this example 231 >> 7 = 0x01. this example, 231 >> 7 = 0x01.
9. Fragment Identification Methods 9. Fragment Identification Methods
A SenML Pack typically consists of multiple SenML Records and for A SenML Pack typically consists of multiple SenML Records, and for
some applications it may be useful to be able to refer with a some applications, it may be useful to be able to refer to a single
Fragment Identifier to a single record, or a set of records, in a Record, or a set of Records, in a Pack with a fragment identifier.
Pack. The fragment identifier is only interpreted by a client and The fragment identifier is only interpreted by a client and does not
does not impact retrieval of a representation. The SenML Fragment impact retrieval of a representation. The SenML fragment
Identification is modeled after CSV Fragment Identifiers [RFC7111]. identification is modeled after Comma-Separated Value (CSV) fragment
identifiers [RFC7111].
To select a single SenML Record, the "rec" scheme followed by a To select a single SenML Record, the "rec" scheme followed by a
single number is used. For the purpose of numbering records, the single number is used. For the purpose of numbering Records, the
first record is at position 1. A range of records can be selected by first Record is at position 1. A range of records can be selected by
giving the first and the last record number separated by a '-' giving the first and the last record number separated by a "-"
character. Instead of the second number, the '*' character can be character. Instead of the second number, the "*" character can be
used to indicate the last SenML Record in the Pack. A set of records used to indicate the last SenML Record in the Pack. A set of Records
can also be selected using a comma separated list of record positions can also be selected using a comma-separated list of Record positions
or ranges. or ranges.
(We use the term "selecting a record" for identifying it as part of (We use the term "selecting a Record" for identifying it as part of
the fragment, not in the sense of isolating it from the Pack -- the the fragment, not in the sense of isolating it from the Pack -- the
record still needs to be interpreted as part of the Pack, e.g., using Record still needs to be interpreted as part of the Pack, e.g., using
the base values defined in earlier records) the base values defined in earlier Records.)
9.1. Fragment Identification Examples 9.1. Fragment Identification Examples
The 3rd SenML Record from "coap://example.com/temp" resource can be The 3rd SenML Record from the "coap://example.com/temp" resource can
selected with: be selected with:
coap://example.com/temp#rec=3 coap://example.com/temp#rec=3
Records from 3rd to 6th can be selected with: Records from 3rd to 6th can be selected with:
coap://example.com/temp#rec=3-6 coap://example.com/temp#rec=3-6
Records from 19th to the last can be selected with: Records from 19th to the last can be selected with:
coap://example.com/temp#rec=19-* coap://example.com/temp#rec=19-*
The 3rd and 5th record can be selected with: The 3rd and 5th Records can be selected with:
coap://example.com/temp#rec=3,5 coap://example.com/temp#rec=3,5
To select the Records from third to fifth, the 10th record, and all To select the Records from third to fifth, the 10th Record, and all
from 19th to the last: Records from 19th to the last:
coap://example.com/temp#rec=3-5,10,19-* coap://example.com/temp#rec=3-5,10,19-*
9.2. Fragment Identification for the XML and EXI Formats 9.2. Fragment Identification for XML and EXI Formats
In addition to the SenML Fragment Identifiers described above, with In addition to the SenML fragment identifiers described above, with
the XML and EXI SenML formats also the syntax defined in the XPointer the XML and EXI SenML formats, the syntax defined in the XPointer
element() Scheme [XPointerElement] of the XPointer Framework element() Scheme [XPointerElement] of the XPointer Framework
[XPointerFramework] can be used. (This is required by [RFC7303] for [XPointerFramework] can be used. (This is required by [RFC7303] for
media types using the "+xml" structured syntax suffix. SenML allows media types using the syntax suffix structured with "+xml". For
this for the EXI formats as well for consistency.) consistency, SenML allows this for the EXI formats as well.)
Note that fragment identifiers are available to the client side only; Note that fragment identifiers are available to the client side only;
they are not provided in transfer protocols such as CoAP or HTTP. they are not provided in transfer protocols such as CoAP or HTTP.
Thus, they cannot be used by the server in deciding which media type Thus, they cannot be used by the server in deciding which media type
to send. Where a server has multiple representations available for a to send. Where a server has multiple representations available for a
resource identified by a URI, it might send a JSON or CBOR resource identified by a URI, it might send a JSON or CBOR
representation when the client was directed to use an XML/EXI representation when the client was directed to use an XML/EXI
fragment identifier with this. Clients can prevent running into this fragment identifier with it. Clients can prevent running into this
problem by explicitly requesting an XML or EXI media type (e.g., problem by explicitly requesting an XML or EXI media type (e.g.,
using the CoAP Accept option) when XML/EXI-only fragment identifier using the CoAP Accept option) when XML-/EXI-only fragment identifier
syntax is in use in the URI. syntax is in use in the URI.
10. Usage Considerations 10. Usage Considerations
The measurements support sending both the current value of a sensor The measurements support sending both the current value of a sensor
as well as an integrated sum. For many types of measurements, the as well as an integrated sum. For many types of measurements, the
sum is more useful than the current value. For historical reasons, sum is more useful than the current value. For historical reasons,
this field is called "sum" instead of "integral" which would more this field is called "Sum" instead of "integral", which would more
accurately describe its function. For example, an electrical meter accurately describe its function. For example, an electrical meter
that measures the energy a given computer uses will typically want to that measures the energy a given computer uses will typically want to
measure the cumulative amount of energy used. This is less prone to measure the cumulative amount of energy used. This is less prone to
error than reporting the power each second and trying to have error than reporting the power each second and trying to have
something on the server side sum together all the power measurements. something on the server side sum together all the power measurements.
If the network between the sensor and the meter goes down over some If the network between the sensor and the meter goes down over some
period of time, when it comes back up, the cumulative sum helps period of time, when it comes back up, the cumulative sum helps
reflect what happened while the network was down. A meter like this reflect what happened while the network was down. A meter like this
would typically report a measurement with the unit set to watts, but would typically report a measurement with the unit set to watts, but
it would put the sum of energy used in the "s" field of the it would put the sum of energy used in the "s" field of the
skipping to change at page 27, line 5 skipping to change at page 28, line 5
"v" field. "v" field.
While the benefit of using the integrated sum is fairly clear for While the benefit of using the integrated sum is fairly clear for
measurements like power and energy, it is less obvious for something measurements like power and energy, it is less obvious for something
like temperature. Reporting the sum of the temperature makes it easy like temperature. Reporting the sum of the temperature makes it easy
to compute averages even when the individual temperature values are to compute averages even when the individual temperature values are
not reported frequently enough to compute accurate averages. not reported frequently enough to compute accurate averages.
Implementers are encouraged to report the cumulative sum as well as Implementers are encouraged to report the cumulative sum as well as
the raw value of a given sensor. the raw value of a given sensor.
Applications that use the cumulative sum values need to understand Applications that use the cumulative Sum values need to understand
they are very loosely defined by this specification, and depending on they are very loosely defined by this specification, and depending on
the particular sensor implementation may behave in unexpected ways. the particular sensor implementation, they may behave in unexpected
Applications should be able to deal with the following issues: ways. Applications should be able to deal with the following issues:
1. Many sensors will allow the cumulative sums to "wrap" back to 1. Many sensors will allow the cumulative sums to "wrap" back to
zero after the value gets sufficiently large. zero after the value gets sufficiently large.
2. Some sensors will reset the cumulative sum back to zero when the 2. Some sensors will reset the cumulative sum back to zero when the
device is reset, loses power, or is replaced with a different device is reset, loses power, or is replaced with a different
sensor. sensor.
3. Applications cannot make assumptions about when the device 3. Applications cannot make assumptions about when the device
started accumulating values into the sum. started accumulating values into the sum.
Typically applications can make some assumptions about specific Typically, applications can make some assumptions about specific
sensors that will allow them to deal with these problems. A common sensors that will allow them to deal with these problems. A common
assumption is that for sensors whose measurement values are always assumption is that for sensors whose measurement values are non-
positive, the sum should never get smaller; so if the sum does get negative, the sum should never get smaller; if the sum does get
smaller, the application will know that one of the situations listed smaller, the application will know that one of the situations listed
above has happened. above has happened.
Despite the name sum, the sum field is not useful for applications Despite the name "Sum", the Sum field is not useful for applications
that maintain a running count of the number of times that an event that maintain a running count of the number of times an event
happened or keeping track of a counter such as the total number of happened or that keep track of a counter such as the total number of
bytes sent on an interface. Data like that can be sent directly in bytes sent on an interface. Data like that can be sent directly in
the value field. the Value field.
11. CDDL 11. CDDL
As a convenient reference, the JSON and CBOR representations can be As a convenient reference, the JSON and CBOR representations can be
described with the common CDDL [I-D.ietf-cbor-cddl] specification in described with the common Concise Data Definition Language (CDDL)
Figure 1 (informative). specification [CDDL-CBOR] in Figure 1 (informative).
SenML-Pack = [1* record] SenML-Pack = [1* record]
record = { record = {
? bn => tstr, ; Base Name ? bn => tstr, ; Base Name
? bt => numeric, ; Base Time ? bt => numeric, ; Base Time
? bu => tstr, ; Base Units ? bu => tstr, ; Base Units
? bv => numeric, ; Base Value ? bv => numeric, ; Base Value
? bs => numeric, ; Base Sum ? bs => numeric, ; Base Sum
? bver => uint, ; Base Version ? bver => uint, ; Base Version
? n => tstr, ; Name ? n => tstr, ; Name
? u => tstr, ; Units ? u => tstr, ; Units
? s => numeric, ; Value Sum ? s => numeric, ; Sum
? t => numeric, ; Time ? t => numeric, ; Time
? ut => numeric, ; Update Time ? ut => numeric, ; Update Time
? ( v => numeric // ; Numeric Value ? ( v => numeric // ; Numeric Value
vs => tstr // ; String Value vs => tstr // ; String Value
vb => bool // ; Boolean Value vb => bool // ; Boolean Value
vd => binary-value ) ; Data Value vd => binary-value ) ; Data Value
* key-value-pair * key-value-pair
} }
; now define the generic versions ; now define the generic versions
key-value-pair = ( label => value ) key-value-pair = ( label => value )
label = non-b-label / b-label label = non-b-label / b-label
non-b-label = tstr .regexp "[A-Zac-z0-9][-_:.A-Za-z0-9]*" / uint non-b-label = tstr .regexp "[A-Zac-z0-9][-_:.A-Za-z0-9]*" / uint
b-label = tstr .regexp "b[-_:.A-Za-z0-9]+" / nint b-label = tstr .regexp "b[-_:.A-Za-z0-9]+" / nint
value = tstr / binary-value / numeric / bool value = tstr / binary-value / numeric / bool
numeric = number / decfrac numeric = number / decfrac
Figure 1: Common CDDL specification for CBOR and JSON SenML Figure 1: Common CDDL Specification for CBOR and JSON SenML
For JSON, we use text labels and base64url-encoded binary data For JSON, we use text labels and base64url-encoded binary data
(Figure 2). (Figure 2).
bver = "bver" n = "n" s = "s" bver = "bver" n = "n" s = "s"
bn = "bn" u = "u" t = "t" bn = "bn" u = "u" t = "t"
bt = "bt" v = "v" ut = "ut" bt = "bt" v = "v" ut = "ut"
bu = "bu" vs = "vs" vd = "vd" bu = "bu" vs = "vs" vd = "vd"
bv = "bv" vb = "vb" bv = "bv" vb = "vb"
bs = "bs" bs = "bs"
binary-value = tstr ; base64url encoded binary-value = tstr ; base64url encoded
Figure 2: JSON-specific CDDL specification for SenML Figure 2: JSON-Specific CDDL Specification for SenML
For CBOR, we use integer labels and native binary data (Figure 3). For CBOR, we use integer labels and native binary data (Figure 3).
bver = -1 n = 0 s = 5 bver = -1 n = 0 s = 5
bn = -2 u = 1 t = 6 bn = -2 u = 1 t = 6
bt = -3 v = 2 ut = 7 bt = -3 v = 2 ut = 7
bu = -4 vs = 3 vd = 8 bu = -4 vs = 3 vd = 8
bv = -5 vb = 4 bv = -5 vb = 4
bs = -6 bs = -6
binary-value = bstr binary-value = bstr
Figure 3: CBOR-specific CDDL specification for SenML Figure 3: CBOR-Specific CDDL Specification for SenML
12. IANA Considerations 12. IANA Considerations
Note to RFC Editor: Please replace all occurrences of "RFC-AAAA" with IANA has created a new "Sensor Measurement Lists (SenML)" registry
the RFC number of this specification. that contains the subregistries defined in Sections 12.1 and 12.2.
IANA will create a new registry for "Sensor Measurement Lists (SenML)
Parameters". The sub-registries defined in Section 12.1 and
Section 12.2 will be created inside this registry.
12.1. Units Registry 12.1. SenML Units Registry
IANA will create a registry of SenML unit symbols. The primary IANA has created a registry of SenML unit symbols called the "SenML
purpose of this registry is to make sure that symbols uniquely map to Units" registry. The primary purpose of this registry is to make
give type of measurement. Definitions for many of these units can be sure that symbols uniquely map to indicate a type of measurement.
found in location such as [NIST811] and [BIPM]. Units marked with an Definitions for many of these units can be found in other
asterisk are NOT RECOMMENDED to be produced by new implementations, publications such as [NIST811] and [BIPM]. Units marked with an
asterisk are NOT RECOMMENDED to be produced by new implementations
but are in active use and SHOULD be implemented by consumers that can but are in active use and SHOULD be implemented by consumers that can
use the related base units. use the corresponding SenML units that are closer to the unscaled SI
units.
+----------+------------------------------------+-------+-----------+ +----------+------------------------------------+-------+-----------+
| Symbol | Description | Type | Reference | | Symbol | Description | Type | Reference |
+----------+------------------------------------+-------+-----------+ +----------+------------------------------------+-------+-----------+
| m | meter | float | RFC-AAAA | | m | meter | float | RFC 8428 |
| kg | kilogram | float | RFC-AAAA | | kg | kilogram | float | RFC 8428 |
| g | gram* | float | RFC-AAAA | | g | gram* | float | RFC 8428 |
| s | second | float | RFC-AAAA | | s | second | float | RFC 8428 |
| A | ampere | float | RFC-AAAA | | A | ampere | float | RFC 8428 |
| K | kelvin | float | RFC-AAAA | | K | kelvin | float | RFC 8428 |
| cd | candela | float | RFC-AAAA | | cd | candela | float | RFC 8428 |
| mol | mole | float | RFC-AAAA | | mol | mole | float | RFC 8428 |
| Hz | hertz | float | RFC-AAAA | | Hz | hertz | float | RFC 8428 |
| rad | radian | float | RFC-AAAA | | rad | radian | float | RFC 8428 |
| sr | steradian | float | RFC-AAAA | | sr | steradian | float | RFC 8428 |
| N | newton | float | RFC-AAAA | | N | newton | float | RFC 8428 |
| Pa | pascal | float | RFC-AAAA | | Pa | pascal | float | RFC 8428 |
| J | joule | float | RFC-AAAA | | J | joule | float | RFC 8428 |
| W | watt | float | RFC-AAAA | | W | watt | float | RFC 8428 |
| C | coulomb | float | RFC-AAAA | | C | coulomb | float | RFC 8428 |
| V | volt | float | RFC-AAAA | | V | volt | float | RFC 8428 |
| F | farad | float | RFC-AAAA | | F | farad | float | RFC 8428 |
| Ohm | ohm | float | RFC-AAAA | | Ohm | ohm | float | RFC 8428 |
| S | siemens | float | RFC-AAAA | | S | siemens | float | RFC 8428 |
| Wb | weber | float | RFC-AAAA | | Wb | weber | float | RFC 8428 |
| T | tesla | float | RFC-AAAA | | T | tesla | float | RFC 8428 |
| H | henry | float | RFC-AAAA | | H | henry | float | RFC 8428 |
| Cel | degrees Celsius | float | RFC-AAAA | | Cel | degrees Celsius | float | RFC 8428 |
| lm | lumen | float | RFC-AAAA | | lm | lumen | float | RFC 8428 |
| lx | lux | float | RFC-AAAA | | lx | lux | float | RFC 8428 |
| Bq | becquerel | float | RFC-AAAA | | Bq | becquerel | float | RFC 8428 |
| Gy | gray | float | RFC-AAAA | | Gy | gray | float | RFC 8428 |
| Sv | sievert | float | RFC-AAAA | | Sv | sievert | float | RFC 8428 |
| kat | katal | float | RFC-AAAA | | kat | katal | float | RFC 8428 |
| m2 | square meter (area) | float | RFC-AAAA | | m2 | square meter (area) | float | RFC 8428 |
| m3 | cubic meter (volume) | float | RFC-AAAA | | m3 | cubic meter (volume) | float | RFC 8428 |
| l | liter (volume)* | float | RFC-AAAA | | l | liter (volume)* | float | RFC 8428 |
| m/s | meter per second (velocity) | float | RFC-AAAA | | m/s | meter per second (velocity) | float | RFC 8428 |
| m/s2 | meter per square second | float | RFC-AAAA | | m/s2 | meter per square second | float | RFC 8428 |
| | (acceleration) | | | | | (acceleration) | | |
| m3/s | cubic meter per second (flow rate) | float | RFC-AAAA | | m3/s | cubic meter per second (flow rate) | float | RFC 8428 |
| l/s | liter per second (flow rate)* | float | RFC-AAAA | | l/s | liter per second (flow rate)* | float | RFC 8428 |
| W/m2 | watt per square meter (irradiance) | float | RFC-AAAA | | W/m2 | watt per square meter (irradiance) | float | RFC 8428 |
| cd/m2 | candela per square meter | float | RFC-AAAA | | cd/m2 | candela per square meter | float | RFC 8428 |
| | (luminance) | | | | | (luminance) | | |
| bit | bit (information content) | float | RFC-AAAA | | bit | bit (information content) | float | RFC 8428 |
| bit/s | bit per second (data rate) | float | RFC-AAAA | | bit/s | bit per second (data rate) | float | RFC 8428 |
| lat | degrees latitude (note 1) | float | RFC-AAAA | | lat | degrees latitude (Note 1) | float | RFC 8428 |
| lon | degrees longitude (note 1) | float | RFC-AAAA | | lon | degrees longitude (Note 1) | float | RFC 8428 |
| pH | pH value (acidity; logarithmic | float | RFC-AAAA | | pH | pH value (acidity; logarithmic | float | RFC 8428 |
| | quantity) | | | | | quantity) | | |
| dB | decibel (logarithmic quantity) | float | RFC-AAAA | | dB | decibel (logarithmic quantity) | float | RFC 8428 |
| dBW | decibel relative to 1 W (power | float | RFC-AAAA | | dBW | decibel relative to 1 W (power | float | RFC 8428 |
| | level) | | | | | level) | | |
| Bspl | bel (sound pressure level; | float | RFC-AAAA | | Bspl | bel (sound pressure level; | float | RFC 8428 |
| | logarithmic quantity)* | | | | | logarithmic quantity)* | | |
| count | 1 (counter value) | float | RFC-AAAA | | count | 1 (counter value) | float | RFC 8428 |
| / | 1 (Ratio e.g., value of a switch, | float | RFC-AAAA | | / | 1 (ratio, e.g., value of a switch; | float | RFC 8428 |
| | note 2) | | | | | Note 2) | | |
| % | 1 (Ratio e.g., value of a switch, | float | RFC-AAAA | | % | 1 (ratio, e.g., value of a switch; | float | RFC 8428 |
| | note 2)* | | | | | Note 2)* | | |
| %RH | Percentage (Relative Humidity) | float | RFC-AAAA | | %RH | percentage (relative humidity) | float | RFC 8428 |
| %EL | Percentage (remaining battery | float | RFC-AAAA | | %EL | percentage (remaining battery | float | RFC 8428 |
| | energy level) | | | | | energy level) | | |
| EL | seconds (remaining battery energy | float | RFC-AAAA | | EL | seconds (remaining battery energy | float | RFC 8428 |
| | level) | | | | | level) | | |
| 1/s | 1 per second (event rate) | float | RFC-AAAA | | 1/s | 1 per second (event rate) | float | RFC 8428 |
| 1/min | 1 per minute (event rate, "rpm")* | float | RFC-AAAA | | 1/min | 1 per minute (event rate, "rpm")* | float | RFC 8428 |
| beat/min | 1 per minute (Heart rate in beats | float | RFC-AAAA | | beat/min | 1 per minute (heart rate in beats | float | RFC 8428 |
| | per minute)* | | | | | per minute)* | | |
| beats | 1 (Cumulative number of heart | float | RFC-AAAA | | beats | 1 (cumulative number of heart | float | RFC 8428 |
| | beats)* | | | | | beats)* | | |
| S/m | Siemens per meter (conductivity) | float | RFC-AAAA | | S/m | siemens per meter (conductivity) | float | RFC 8428 |
+----------+------------------------------------+-------+-----------+ +----------+------------------------------------+-------+-----------+
Table 6 Table 6: IANA Registry for SenML Units
o Note 1: Assumed to be in WGS84 unless another reference frame is o Note 1: Assumed to be in World Geodetic System 1984 (WGS84),
known for the sensor. unless another reference frame is known for the sensor.
o Note 2: A value of 0.0 indicates the switch is off while 1.0 o Note 2: A value of 0.0 indicates the switch is off, 1.0 indicates
indicates on and 0.5 would be half on. The preferred name of this on, and 0.5 indicates half on. The preferred name of this unit is
unit is "/". For historical reasons, the name "%" is also "/". For historical reasons, the name "%" is also provided for
provided for the same unit - but note that while that name the same unit, but note that while that name strongly suggests a
strongly suggests a percentage (0..100) -- it is however NOT a percentage (0..100), it is NOT a percentage but the absolute
percentage, but the absolute ratio! ratio!
New entries can be added to the registration by Expert Review as New entries can be added to the registration by Expert Review as
defined in [RFC8126]. Experts should exercise their own good defined in [RFC8126]. Experts should exercise their own good
judgment but need to consider the following guidelines: judgment but need to consider the following guidelines:
1. There needs to be a real and compelling use for any new unit to 1. There needs to be a real and compelling use for any new unit to
be added. be added.
2. Each unit should define the semantic information and be chosen 2. Each unit should define the semantic information and be chosen
carefully. Implementers need to remember that the same word may carefully. Implementers need to remember that the same word may
be used in different real-life contexts. For example, degrees be used in different real-life contexts. For example, degrees
when measuring latitude have no semantic relation to degrees when measuring latitude have no semantic relation to degrees
when measuring temperature; thus two different units are needed. when measuring temperature; thus, two different units are
needed.
3. These measurements are produced by computers for consumption by 3. These measurements are produced by computers for consumption by
computers. The principle is that conversion has to be easily be computers. The principle is that conversion has to be easily
done when both reading and writing the media type. The value of done when both reading and writing the media type. The value of
a single canonical representation outweighs the convenience of a single canonical representation outweighs the convenience of
easy human representations or loss of precision in a conversion. easy human representations or loss of precision in a conversion.
4. Use of SI prefixes such as "k" before the unit is not 4. Use of System of Units (SI) prefixes such as "k" before the unit
recommended. Instead one can represent the value using is not recommended. Instead, one can represent the value using
scientific notation such a 1.2e3. The "kg" unit is exception to scientific notation such as 1.2e3. The "kg" unit is an
this rule since it is an SI base unit; the "g" unit is provided exception to this rule since it is an SI base unit; the "g" unit
for legacy compatibility. is provided for legacy compatibility.
5. For a given type of measurement, there will only be one unit 5. For a given type of measurement, there will only be one unit
type defined. So for length, meters are defined and other type defined. So for length, meter is defined, and other
lengths such as mile, foot, light year are not allowed. For lengths such as mile, foot, and light year are not allowed. For
most cases, the SI unit is preferred. most cases, the SI unit is preferred.
(Note that some amount of judgment will be required here, as (Note that some amount of judgment will be required here, as
even SI itself is not entirely consistent in this respect. For even SI itself is not entirely consistent in this respect. For
instance, for temperature [ISO-80000-5] defines a quantity, item instance, for temperature, [ISO-80000-5] defines a quantity,
5-1 (thermodynamic temperature), and a corresponding unit 5-1.a item 5-1 (thermodynamic temperature), and a corresponding unit
(Kelvin), and then goes ahead to define another quantity right of 5-1.a (Kelvin); [ISO-80000-5] goes on to define another
besides that, item 5-2 ("Celsius temperature"), and the quantity, item 5-2 ("Celsius temperature"), and the
corresponding unit 5-2.a (degree Celsius). The latter quantity corresponding unit of 5-2.a (degree Celsius). The latter
is defined such that it gives the thermodynamic temperature as a quantity is defined such that it gives the thermodynamic
delta from T0 = 275.15 K. ISO 80000-5 is defining both units temperature as a delta from T0 = 275.15 K. ISO 80000-5 is
side by side, and not really expressing a preference. This defining both units side by side and not really expressing a
level of recognition of the alternative unit degree Celsius is preference. This level of recognition of the alternative unit
the reason why Celsius temperatures exceptionally seem degree Celsius is the reason why Celsius temperatures seem
acceptable in the SenML units list alongside Kelvin.) exceptionally acceptable in the SenML units list alongside
Kelvin.)
6. Symbol names that could be easily confused with existing common 6. Symbol names that could be easily confused with existing common
units or units combined with prefixes should be avoided. For units or units combined with prefixes should be avoided. For
example, selecting a unit name of "mph" to indicate something example, selecting a unit name of "mph" to indicate something
that had nothing to do with velocity would be a bad choice, as that had nothing to do with velocity would be a bad choice, as
"mph" is commonly used to mean miles per hour. "mph" is commonly used to mean "miles per hour".
7. The following should not be used because the are common SI 7. The following should not be used because they are common SI
prefixes: Y, Z, E, P, T, G, M, k, h, da, d, c, n, u, p, f, a, z, prefixes: Y, Z, E, P, T, G, M, k, h, da, d, c, u, n, p, f, a, z,
y, Ki, Mi, Gi, Ti, Pi, Ei, Zi, Yi. y, Ki, Mi, Gi, Ti, Pi, Ei, Zi, and Yi.
8. The following units should not be used as they are commonly used 8. The following units should not be used as they are commonly used
to represent other measurements Ky, Gal, dyn, etg, P, St, Mx, G, to represent other measurements: Ky, Gal, dyn, etg, P, St, Mx,
Oe, Gb, sb, Lmb, mph, Ci, R, RAD, REM, gal, bbl, qt, degF, Cal, G, Oe, Gb, sb, Lmb, mph, Ci, R, RAD, REM, gal, bbl, qt, degF,
BTU, HP, pH, B/s, psi, Torr, atm, at, bar, kWh. Cal, BTU, HP, pH, B/s, psi, Torr, atm, at, bar, and kWh.
9. The unit names are case sensitive and the correct case needs to 9. The unit names are case sensitive, and the correct case needs to
be used, but symbols that differ only in case should not be be used; however, symbols that differ only in case should not be
allocated. allocated.
10. A number after a unit typically indicates the previous unit 10. A number after a unit typically indicates the previous unit
raised to that power, and the / indicates that the units that raised to that power, and "/" indicates that the units that
follow are the reciprocal. A unit should have only one / in the follow are the reciprocals. A unit should have only one "/" in
name. the name.
11. A good list of common units can be found in the Unified Code for 11. A good list of common units can be found in the Unified Code for
Units of Measure [UCUM]. Units of Measure [UCUM].
12.2. SenML Label Registry 12.2. SenML Labels Registry
IANA will create a new registry for SenML labels. The initial IANA has created a new registry for SenML Labels called the "SenML
content of the registry is: Labels" registry. The initial contents of the registry are as
follows:
+--------------+-------+----+-----------+----------+----+-----------+ +--------------+-------+----+-----------+----------+----+-----------+
| Name | Label | CL | JSON Type | XML Type | EI | Reference | | Name | Label | CL | JSON Type | XML Type | EI | Reference |
+--------------+-------+----+-----------+----------+----+-----------+ +--------------+-------+----+-----------+----------+----+-----------+
| Base Name | bn | -2 | String | string | a | RFC-AAAA | | Base Name | bn | -2 | String | string | a | RFC 8428 |
| Base Time | bt | -3 | Number | double | a | RFC-AAAA | | Base Time | bt | -3 | Number | double | a | RFC 8428 |
| Base Unit | bu | -4 | String | string | a | RFC-AAAA | | Base Unit | bu | -4 | String | string | a | RFC 8428 |
| Base Value | bv | -5 | Number | double | a | RFC-AAAA | | Base Value | bv | -5 | Number | double | a | RFC 8428 |
| Base Sum | bs | -6 | Number | double | a | RFC-AAAA | | Base Sum | bs | -6 | Number | double | a | RFC 8428 |
| Base Version | bver | -1 | Number | int | a | RFC-AAAA | | Base Version | bver | -1 | Number | int | a | RFC 8428 |
| Name | n | 0 | String | string | a | RFC-AAAA | | Name | n | 0 | String | string | a | RFC 8428 |
| Unit | u | 1 | String | string | a | RFC-AAAA | | Unit | u | 1 | String | string | a | RFC 8428 |
| Value | v | 2 | Number | double | a | RFC-AAAA | | Value | v | 2 | Number | double | a | RFC 8428 |
| String Value | vs | 3 | String | string | a | RFC-AAAA | | String Value | vs | 3 | String | string | a | RFC 8428 |
| Boolean | vb | 4 | Boolean | boolean | a | RFC-AAAA | | Boolean | vb | 4 | Boolean | boolean | a | RFC 8428 |
| Value | | | | | | | | Value | | | | | | |
| Data Value | vd | 8 | String | string | a | RFC-AAAA | | Data Value | vd | 8 | String | string | a | RFC 8428 |
| Value Sum | s | 5 | Number | double | a | RFC-AAAA | | Sum | s | 5 | Number | double | a | RFC 8428 |
| Time | t | 6 | Number | double | a | RFC-AAAA | | Time | t | 6 | Number | double | a | RFC 8428 |
| Update Time | ut | 7 | Number | double | a | RFC-AAAA | | Update Time | ut | 7 | Number | double | a | RFC 8428 |
+--------------+-------+----+-----------+----------+----+-----------+ +--------------+-------+----+-----------+----------+----+-----------+
Table 7: IANA Registry for SenML Labels, CL = CBOR Label, EI = EXI ID Note that CL = CBOR Label and EI = EXI ID.
This is the same table as Table 1, with notes removed, and with Table 7: IANA Registry for SenML Labels
columns added for the information that is all the same for this
initial set of registrations, but will need to be supplied with a
different value for new registrations.
All new entries must define the Label Name, Label, and XML Type but This is the same table as Table 1, with notes removed and columns
the CBOR labels SHOULD be left empty as CBOR will use the string added for the information that is all the same for this initial set
encoding for any new labels. The EI column contains the EXI schemaId of registrations, but it will need to be supplied with different
value of the first Schema which includes this label or is empty if values for new registrations.
this label was not intended for use with EXI. The Note field SHOULD
All new entries must define the Name, Label, and XML Type, but the
CBOR labels SHOULD be left empty as CBOR will use the string encoding
for any new labels. The EI column contains the EXI schemaId value of
the first schema that includes this label, or it is empty if this
label was not intended for use with EXI. The Reference column SHOULD
contain information about where to find out more information about contain information about where to find out more information about
this label. this label.
The JSON, CBOR, and EXI types are derived from the XML type. All XML The JSON, CBOR, and EXI types are derived from the XML type. All XML
numeric types such as double, float, integer and int become a JSON numeric types such as double, float, integer, and int become a JSON
Number. XML boolean and string become a JSON Boolean and String Number. XML boolean and string become a JSON Boolean and String,
respectively. CBOR represents numeric values with a CBOR type that respectively. CBOR represents numeric values with a CBOR type that
does not lose any information from the JSON value. EXI uses the XML does not lose any information from the JSON value. EXI uses the XML
types. types.
New entries can be added to the registration by Expert Review as New entries can be added to the registration by Expert Review as
defined in [RFC8126]. Experts should exercise their own good defined in [RFC8126]. Experts should exercise their own good
judgment but need to consider that shorter labels should have more judgment but need to consider that shorter labels should have more
strict review. New entries should not be made that counteract the strict review. New entries should not be made that counteract the
advice at the end of Section 4.5.4. advice at the end of Section 4.5.4.
All new SenML labels that have "base" semantics (see Section 4.1) All new SenML Labels that have "base" semantics (see Section 4.1)
MUST start with the character 'b'. Regular labels MUST NOT start MUST start with the character "b". Regular labels MUST NOT start
with that character. All new SenML labels with Value semantics (see with that character. All new SenML Labels with Value semantics (see
Section 4.2) MUST have "Value" in their (long form) name. Section 4.2) MUST have "Value" in their (long-form) name.
Extensions that add a label that is intended for use with XML need to Extensions that add a label intended for use with XML need to create
create a new RelaxNG scheme that includes all the labels in the IANA a new RelaxNG Schema that includes all the labels in the "SenML
registry. Labels" registry.
Extensions that add a label that is intended for use with EXI need to Extensions that add a label that is intended for use with EXI need to
create a new XSD Schema that includes all the labels in the IANA create a new XSD Schema that includes all the labels in the "SenML
registry and then allocate a new EXI schemaId value. Moving to the Labels" registry and then allocate a new EXI schemaId value. Moving
next letter in the alphabet is the suggested way to create the new to the next letter in the alphabet is the suggested way to create the
value for the EXI schemaId. Any labels with previously blank ID new value for the EXI schemaId. Any labels with previously blank ID
values SHOULD be updated in the IANA table to have their ID set to values SHOULD be updated in the "SenML Labels" registry to have their
this new schemaId value. ID set to this new schemaId value.
Extensions that are mandatory to understand to correctly process the Extensions that are mandatory to understand to correctly process the
Pack MUST have a label name that ends with the '_' character. Pack MUST have a label name that ends with the "_" character.
12.3. Media Type Registrations 12.3. Media Type Registrations
The following registrations are done following the procedure The registrations in the subsections below follow the procedures
specified in [RFC6838] and [RFC7303]. This document registers media specified in [RFC6838] and [RFC7303]. This document registers media
types for each serialization format of SenML (JSON, CBOR, XML, and types for each serialization format of SenML (JSON, CBOR, XML, and
EXI) and also a corresponding set of media types for the streaming EXI) and also a corresponding set of media types for streaming use
use (SensML, see Section 4.8). Clipboard formats are defined for the (SenSML; see Section 4.8). Clipboard formats are defined for the
JSON and XML forms of SenML but not for streams or non-textual JSON and XML forms of SenML but not for streams or non-textual
formats. formats.
The reason there are both SenML and the streaming SensML formats is The reason there are both SenML and the streaming SenSML formats is
that they are not the same data formats and they require separate that they are not the same data formats, and they require separate
negotiation to understand if they are supported and which one is negotiation to understand if they are supported and which one is
being used. The non streaming format is required to have some sort being used. The non-streaming format is required to have some sort
of end of pack syntax which indicates there will be no more records. of end-of-pack syntax that indicates there will be no more records.
Many implementations that receive SenML wait for this end of pack Many implementations that receive SenML wait for this end-of-pack
marker before processing any of the records. On the other hand, with marker before processing any of the records. On the other hand, with
the streaming formats, it is explicitly not required to wait for this the streaming formats, it is explicitly not required to wait for this
end of pack marker. Many implementations that produce streaming end-of-pack marker. Many implementations that produce streaming
SensML will never send this end of pack marker so implementations SenSML will never send this end-of-pack marker, so implementations
that receive streaming SensML can not wait for the end of pack marker that receive streaming SenSML cannot wait for the end-of-pack marker
before they start processing the records. Given the SenML and before they start processing the records. Given that SenML and
streaming SenML are different data formats, and the requirement for streaming SenML are different data formats, and considering the
separate negotiation, a media type for each one is needed. requirement for separate negotiation, a media type for each one is
needed.
Note to RFC Editor - please remove this paragraph. Note that a
request for media type review for senml+json was sent to the media-
types@iana.org on Sept 21, 2010. A second request for all the types
was sent on October 31, 2016. Please change all instances of RFC-
AAAA with the RFC number of this document.
12.3.1. senml+json Media Type Registration 12.3.1. senml+json Media Type Registration
Type name: application Type name: application
Subtype name: senml+json Subtype name: senml+json
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: Must be encoded as using a subset of the Encoding considerations: Must be encoded as using a subset of the
encoding allowed in [RFC8259]. See RFC-AAAA for details. This encoding allowed in [RFC8259]. See RFC 8428 for details. This
simplifies implementation of very simple system and does not impose simplifies implementation of a very simple system and does not impose
any significant limitations as all this data is meant for machine to any significant limitations as all this data is meant for machine-to-
machine communications and is not meant to be human readable. machine communications and is not meant to be human readable.
Security considerations: See Section 13 of RFC-AAAA. Security considerations: See Section 13 of RFC 8428.
Interoperability considerations: Applications MUST ignore any JSON Interoperability considerations: Applications MUST ignore any JSON
key value pairs that they do not understand unless the key ends with key-value pairs that they do not understand unless the key ends with
the '_' character in which case an error MUST be generated. This the "_" character, in which case an error MUST be generated. This
allows backwards compatible extensions to this specification. The allows backwards-compatible extensions to this specification. The
"bver" field can be used to ensure the receiver supports a minimal "bver" field can be used to ensure the receiver supports a minimal
level of functionality needed by the creator of the JSON object. level of functionality needed by the creator of the JSON object.
Published specification: RFC-AAAA Published specification: RFC 8428
Applications that use this media type: The type is used by systems Applications that use this media type: The type is used by systems
that report e.g., electrical power usage and environmental that report, e.g., electrical power usage and environmental
information such as temperature and humidity. It can be used for a information such as temperature and humidity. It can be used for a
wide range of sensor reporting systems. wide range of sensor reporting systems.
Fragment identifier considerations: Fragment identification for Fragment identifier considerations: Fragment identification for
application/senml+json is supported by using fragment identifiers as application/senml+json is supported by using fragment identifiers as
specified by RFC-AAAA. specified by RFC 8428.
Additional information: Additional information:
Magic number(s): none Deprecated alias names for this type: N/A
File extension(s): senml
Windows Clipboard Name: "JSON Sensor Measurement List" Magic number(s): N/A
Macintosh file type code(s): none File extension(s): senml
Macintosh Universal Type Identifier code: org.ietf.senml-json Windows Clipboard Name: "JSON Sensor Measurement List"
conforms to public.text
Person & email address to contact for further information: Cullen Macintosh file type code(s): none
Jennings <fluffy@iii.ca>
Macintosh Universal Type Identifier code: org.ietf.senml-json
conforms to public.text
Person & email address to contact for further information:
Cullen Jennings <fluffy@iii.ca>
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: None Restrictions on usage: None
Author: Cullen Jennings <fluffy@iii.ca> Author: Cullen Jennings <fluffy@iii.ca>
Change controller: IESG Change controller: IESG
12.3.2. sensml+json Media Type Registration 12.3.2. sensml+json Media Type Registration
Type name: application Type name: application
Subtype name: sensml+json Subtype name: sensml+json
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: Must be encoded as using a subset of the Encoding considerations: Must be encoded as using a subset of the
encoding allowed in [RFC8259]. See RFC-AAAA for details. This encoding allowed in [RFC8259]. See RFC 8428 for details. This
simplifies implementation of very simple system and does not impose simplifies implementation of a very simple system and does not impose
any significant limitations as all this data is meant for machine to any significant limitations as all this data is meant for machine-to-
machine communications and is not meant to be human readable. machine communications and is not meant to be human readable.
Security considerations: See Section 13 of RFC-AAAA. Security considerations: See Section 13 of RFC 8428.
Interoperability considerations: Applications MUST ignore any JSON Interoperability considerations: Applications MUST ignore any JSON
key value pairs that they do not understand unless the key ends with key-value pairs that they do not understand unless the key ends with
the '_' character in which case an error MUST be generated. This the "_" character, in which case an error MUST be generated. This
allows backwards compatible extensions to this specification. The allows backwards-compatible extensions to this specification. The
"bver" field can be used to ensure the receiver supports a minimal "bver" field can be used to ensure the receiver supports a minimal
level of functionality needed by the creator of the JSON object. level of functionality needed by the creator of the JSON object.
Published specification: RFC-AAAA Published specification: RFC 8428
Applications that use this media type: The type is used by systems Applications that use this media type: The type is used by systems
that report e.g., electrical power usage and environmental that report, e.g., electrical power usage and environmental
information such as temperature and humidity. It can be used for a information such as temperature and humidity. It can be used for a
wide range of sensor reporting systems. wide range of sensor reporting systems.
Fragment identifier considerations: Fragment identification for Fragment identifier considerations: Fragment identification for
application/sensml+json is supported by using fragment identifiers as application/sensml+json is supported by using fragment identifiers as
specified by RFC-AAAA. specified by RFC 8428.
Additional information: Additional information:
Magic number(s): none Deprecated alias names for this type: N/A
File extension(s): sensml Magic number(s): N/A
Macintosh file type code(s): none File extension(s): sensml
Person & email address to contact for further information: Cullen Macintosh file type code(s): none
Jennings <fluffy@iii.ca>
Person & email address to contact for further information:
Cullen Jennings <fluffy@iii.ca>
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: None Restrictions on usage: None
Author: Cullen Jennings <fluffy@iii.ca> Author: Cullen Jennings <fluffy@iii.ca>
Change controller: IESG Change controller: IESG
12.3.3. senml+cbor Media Type Registration 12.3.3. senml+cbor Media Type Registration
Type name: application Type name: application
Subtype name: senml+cbor Subtype name: senml+cbor
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: Must be encoded as using [RFC7049]. See Encoding considerations: Must be encoded as using [RFC7049]. See RFC
RFC-AAAA for details. 8428 for details.
Security considerations: See Section 13 of RFC-AAAA. Security considerations: See Section 13 of RFC 8428.
Interoperability considerations: Applications MUST ignore any key Interoperability considerations: Applications MUST ignore any key-
value pairs that they do not understand unless the key ends with the value pairs that they do not understand unless the key ends with the
'_' character in which case an error MUST be generated. This allows "_" character, in which case an error MUST be generated. This allows
backwards compatible extensions to this specification. The "bver" backwards-compatible extensions to this specification. The "bver"
field can be used to ensure the receiver supports a minimal level of field can be used to ensure the receiver supports a minimal level of
functionality needed by the creator of the CBOR object. functionality needed by the creator of the CBOR object.
Published specification: RFC-AAAA Published specification: RFC 8428
Applications that use this media type: The type is used by systems Applications that use this media type: The type is used by systems
that report e.g., electrical power usage and environmental that report, e.g., electrical power usage and environmental
information such as temperature and humidity. It can be used for a information such as temperature and humidity. It can be used for a
wide range of sensor reporting systems. wide range of sensor reporting systems.
Fragment identifier considerations: Fragment identification for Fragment identifier considerations: Fragment identification for
application/senml+cbor is supported by using fragment identifiers as application/senml+cbor is supported by using fragment identifiers as
specified by RFC-AAAA. specified by RFC 8428.
Additional information: Additional information:
Magic number(s): none Deprecated alias names for this type: N/A
File extension(s): senmlc Magic number(s): N/A
Macintosh file type code(s): none File extension(s): senmlc
Macintosh Universal Type Identifier code: org.ietf.senml-cbor Macintosh file type code(s): none
conforms to public.data
Person & email address to contact for further information: Cullen Macintosh Universal Type Identifier code: org.ietf.senml-cbor
Jennings <fluffy@iii.ca> conforms to public.data
Person & email address to contact for further information:
Cullen Jennings <fluffy@iii.ca>
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: None Restrictions on usage: None
Author: Cullen Jennings <fluffy@iii.ca> Author: Cullen Jennings <fluffy@iii.ca>
Change controller: IESG Change controller: IESG
12.3.4. sensml+cbor Media Type Registration 12.3.4. sensml+cbor Media Type Registration
Type name: application Type name: application
Subtype name: sensml+cbor Subtype name: sensml+cbor
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: Must be encoded as using [RFC7049]. See Encoding considerations: Must be encoded as using [RFC7049]. See RFC
RFC-AAAA for details. 8428 for details.
Security considerations: See Section 13 of RFC-AAAA. Security considerations: See Section 13 of RFC 8428.
Interoperability considerations: Applications MUST ignore any key Interoperability considerations: Applications MUST ignore any key-
value pairs that they do not understand unless the key ends with the value pairs that they do not understand unless the key ends with the
'_' character in which case an error MUST be generated. This allows "_" character, in which case an error MUST be generated. This allows
backwards compatible extensions to this specification. The "bver" backwards-compatible extensions to this specification. The "bver"
field can be used to ensure the receiver supports a minimal level of field can be used to ensure the receiver supports a minimal level of
functionality needed by the creator of the CBOR object. functionality needed by the creator of the CBOR object.
Published specification: RFC-AAAA Published specification: RFC 8428
Applications that use this media type: The type is used by systems Applications that use this media type: The type is used by systems
that report e.g., electrical power usage and environmental that report, e.g., electrical power usage and environmental
information such as temperature and humidity. It can be used for a information such as temperature and humidity. It can be used for a
wide range of sensor reporting systems. wide range of sensor reporting systems.
Fragment identifier considerations: Fragment identification for Fragment identifier considerations: Fragment identification for
application/sensml+cbor is supported by using fragment identifiers as application/sensml+cbor is supported by using fragment identifiers as
specified by RFC-AAAA. specified by RFC 8428.
Additional information: Additional information:
Magic number(s): none Deprecated alias names for this type: N/A
File extension(s): sensmlc Magic number(s): N/A
Macintosh file type code(s): none File extension(s): sensmlc
Person & email address to contact for further information: Cullen Macintosh file type code(s): none
Jennings <fluffy@iii.ca>
Intended usage: COMMON Person & email address to contact for further information:
Cullen Jennings <fluffy@iii.ca>
Intended usage: COMMON
Restrictions on usage: None Restrictions on usage: None
Author: Cullen Jennings <fluffy@iii.ca> Author: Cullen Jennings <fluffy@iii.ca>
Change controller: IESG Change controller: IESG
12.3.5. senml+xml Media Type Registration 12.3.5. senml+xml Media Type Registration
Type name: application Type name: application
skipping to change at page 40, line 4 skipping to change at page 42, line 19
12.3.5. senml+xml Media Type Registration 12.3.5. senml+xml Media Type Registration
Type name: application Type name: application
Subtype name: senml+xml Subtype name: senml+xml
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: Must be encoded as using Encoding considerations: Must be encoded as using
[W3C.REC-xml-20081126]. See RFC-AAAA for details. [W3C.REC-xml-20081126]. See RFC 8428 for details.
Security considerations: See Section 13 of RFC-AAAA. Security considerations: See Section 13 of RFC 8428.
Interoperability considerations: Applications MUST ignore any XML Interoperability considerations: Applications MUST ignore any XML
tags or attributes that they do not understand unless the attribute tags or attributes that they do not understand unless the attribute
name ends with the '_' character in which case an error MUST be name ends with the "_" character, in which case an error MUST be
generated. This allows backwards compatible extensions to this generated. This allows backwards-compatible extensions to this
specification. The "bver" attribute in the senml XML tag can be used specification. The "bver" attribute in the senml XML tag can be used
to ensure the receiver supports a minimal level of functionality to ensure the receiver supports a minimal level of functionality
needed by the creator of the XML SenML Pack. needed by the creator of the XML SenML Pack.
Published specification: RFC-AAAA Published specification: RFC 8428
Applications that use this media type: The type is used by systems Applications that use this media type: The type is used by systems
that report e.g., electrical power usage and environmental that report, e.g., electrical power usage and environmental
information such as temperature and humidity. It can be used for a information such as temperature and humidity. It can be used for a
wide range of sensor reporting systems. wide range of sensor reporting systems.
Fragment identifier considerations: Fragment identification for Fragment identifier considerations: Fragment identification for
application/senml+xml is supported by using fragment identifiers as application/senml+xml is supported by using fragment identifiers as
specified by RFC-AAAA. specified by RFC 8428.
Additional information: Additional information:
Magic number(s): none Deprecated alias names for this type: N/A
File extension(s): senmlx Magic number(s): N/A
Windows Clipboard Name: "XML Sensor Measurement List" File extension(s): senmlx
Windows Clipboard Name: "XML Sensor Measurement List"
Macintosh file type code(s): none Macintosh file type code(s): none
Macintosh Universal Type Identifier code: org.ietf.senml-xml conforms Macintosh Universal Type Identifier code: org.ietf.senml-xml
to public.xml conforms to public.xml
Person & email address to contact for further information: Cullen Person & email address to contact for further information:
Jennings <fluffy@iii.ca> Cullen Jennings <fluffy@iii.ca>
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: None Restrictions on usage: None
Author: Cullen Jennings <fluffy@iii.ca> Author: Cullen Jennings <fluffy@iii.ca>
Change controller: IESG Change controller: IESG
12.3.6. sensml+xml Media Type Registration 12.3.6. sensml+xml Media Type Registration
Type name: application Type name: application
Subtype name: sensml+xml Subtype name: sensml+xml
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: Must be encoded as using Encoding considerations: Must be encoded as using
[W3C.REC-xml-20081126]. See RFC-AAAA for details. [W3C.REC-xml-20081126]. See RFC 8428 for details.
Security considerations: See Section 13 of RFC-AAAA. Security considerations: See Section 13 of RFC 8428.
Interoperability considerations: Applications MUST ignore any XML Interoperability considerations: Applications MUST ignore any XML
tags or attributes that they do not understand unless the attribute tags or attributes that they do not understand unless the attribute
name ends with the '_' character in which case an error MUST be name ends with the "_" character, in which case an error MUST be
generated. This allows backwards compatible extensions to this generated. This allows backwards-compatible extensions to this
specification. The "bver" attribute in the senml XML tag can be used specification. The "bver" attribute in the senml XML tag can be used
to ensure the receiver supports a minimal level of functionality to ensure the receiver supports a minimal level of functionality
needed by the creator of the XML SenML Pack. needed by the creator of the XML SenML Pack.
Published specification: RFC-AAAA Published specification: RFC 8428
Applications that use this media type: The type is used by systems Applications that use this media type: The type is used by systems
that report e.g., electrical power usage and environmental that report, e.g., electrical power usage and environmental
information such as temperature and humidity. It can be used for a information such as temperature and humidity. It can be used for a
wide range of sensor reporting systems. wide range of sensor reporting systems.
Fragment identifier considerations: Fragment identification for Fragment identifier considerations: Fragment identification for
application/sensml+xml is supported by using fragment identifiers as application/sensml+xml is supported by using fragment identifiers as
specified by RFC-AAAA. specified by RFC 8428.
Additional information: Additional information:
Magic number(s): none Deprecated alias names for this type: N/A
File extension(s): sensmlx Magic number(s): N/A
Macintosh file type code(s): none File extension(s): sensmlx
Person & email address to contact for further information: Cullen Macintosh file type code(s): none
Jennings <fluffy@iii.ca>
Person & email address to contact for further information:
Cullen Jennings <fluffy@iii.ca>
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: None Restrictions on usage: None
Author: Cullen Jennings <fluffy@iii.ca> Author: Cullen Jennings <fluffy@iii.ca>
Change controller: IESG Change controller: IESG
12.3.7. senml-exi Media Type Registration 12.3.7. senml-exi Media Type Registration
Type name: application Type name: application
Subtype name: senml-exi Subtype name: senml-exi
skipping to change at page 42, line 19 skipping to change at page 44, line 41
Type name: application Type name: application
Subtype name: senml-exi Subtype name: senml-exi
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: Must be encoded as using Encoding considerations: Must be encoded as using
[W3C.REC-exi-20140211]. See RFC-AAAA for details. [W3C.REC-exi-20140211]. See RFC 8428 for details.
Security considerations: See Section 13 of RFC-AAAA. Security considerations: See Section 13 of RFC 8428.
Interoperability considerations: Applications MUST ignore any XML Interoperability considerations: Applications MUST ignore any XML
tags or attributes that they do not understand unless the attribute tags or attributes that they do not understand unless the attribute
name ends with the '_' character in which case an error MUST be name ends with the "_" character, in which case an error MUST be
generated. This allows backwards compatible extensions to this generated. This allows backwards-compatible extensions to this
specification. The "bver" attribute in the senml XML tag can be used specification. The "bver" attribute in the senml XML tag can be used
to ensure the receiver supports a minimal level of functionality to ensure the receiver supports a minimal level of functionality
needed by the creator of the XML SenML Pack. Further information on needed by the creator of the XML SenML Pack. Further information on
using schemas to guide the EXI can be found in RFC-AAAA. using schemas to guide the EXI can be found in RFC 8428.
Published specification: RFC-AAAA Published specification: RFC 8428
Applications that use this media type: The type is used by systems Applications that use this media type: The type is used by systems
that report e.g., electrical power usage and environmental that report, e.g., electrical power usage and environmental
information such as temperature and humidity. It can be used for a information such as temperature and humidity. It can be used for a
wide range of sensor reporting systems. wide range of sensor reporting systems.
Fragment identifier considerations: Fragment identification for Fragment identifier considerations: Fragment identification for
application/senml-exi is supported by using fragment identifiers as application/senml-exi is supported by using fragment identifiers as
specified by RFC-AAAA. specified by RFC 8428.
Additional information: Additional information:
Magic number(s): none Deprecated alias names for this type: N/A
File extension(s): senmle Magic number(s): N/A
Macintosh file type code(s): none File extension(s): senmle
Macintosh Universal Type Identifier code: org.ietf.senml-exi conforms
to public.data
Person & email address to contact for further information: Cullen Macintosh file type code(s): none
Jennings <fluffy@iii.ca>
Macintosh Universal Type Identifier code: org.ietf.senml-exi
conforms to public.data
Person & email address to contact for further information:
Cullen Jennings <fluffy@iii.ca>
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: None Restrictions on usage: None
Author: Cullen Jennings <fluffy@iii.ca> Author: Cullen Jennings <fluffy@iii.ca>
Change controller: IESG Change controller: IESG
12.3.8. sensml-exi Media Type Registration 12.3.8. sensml-exi Media Type Registration
Type name: application Type name: application
Subtype name: sensml-exi Subtype name: sensml-exi
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: Must be encoded as using Encoding considerations: Must be encoded as using
[W3C.REC-exi-20140211]. See RFC-AAAA for details. [W3C.REC-exi-20140211]. See RFC 8428 for details.
Security considerations: See Section 13 of RFC-AAAA. Security considerations: See Section 13 of RFC 8428.
Interoperability considerations: Applications MUST ignore any XML Interoperability considerations: Applications MUST ignore any XML
tags or attributes that they do not understand unless the attribute tags or attributes that they do not understand unless the attribute
name ends with the '_' character in which case an error MUST be name ends with the "_" character, in which case an error MUST be
generated. This allows backwards compatible extensions to this generated. This allows backwards-compatible extensions to this
specification. The "bver" attribute in the senml XML tag can be used specification. The "bver" attribute in the senml XML tag can be used
to ensure the receiver supports a minimal level of functionality to ensure the receiver supports a minimal level of functionality
needed by the creator of the XML SenML Pack. Further information on needed by the creator of the XML SenML Pack. Further information on
using schemas to guide the EXI can be found in RFC-AAAA. using schemas to guide the EXI can be found in RFC 8428.
Published specification: RFC-AAAA Published specification: RFC 8428
Applications that use this media type: The type is used by systems Applications that use this media type: The type is used by systems
that report e.g., electrical power usage and environmental that report, e.g., electrical power usage and environmental
information such as temperature and humidity. It can be used for a information such as temperature and humidity. It can be used for a
wide range of sensor reporting systems. wide range of sensor reporting systems.
Fragment identifier considerations: Fragment identification for Fragment identifier considerations: Fragment identification for
application/sensml-exi is supported by using fragment identifiers as application/sensml-exi is supported by using fragment identifiers as
specified by RFC-AAAA. specified by RFC 8428.
Additional information: Additional information:
Magic number(s): none Deprecated alias names for this type: N/A
File extension(s): sensmle Magic number(s): N/A
Macintosh file type code(s): none File extension(s): sensmle
Person & email address to contact for further information: Cullen Macintosh file type code(s): none
Jennings <fluffy@iii.ca>
Person & email address to contact for further information:
Cullen Jennings <fluffy@iii.ca>
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: None Restrictions on usage: None
Author: Cullen Jennings <fluffy@iii.ca> Author: Cullen Jennings <fluffy@iii.ca>
Change controller: IESG Change controller: IESG
12.4. XML Namespace Registration 12.4. XML Namespace Registration
This document registers the following XML namespaces in the IETF XML This document registers the following XML namespace in the "IETF XML
registry defined in [RFC3688]. Registry" defined in [RFC3688].
URI: urn:ietf:params:xml:ns:senml URI: urn:ietf:params:xml:ns:senml
Registrant Contact: The IESG. Registrant Contact: The IESG.
XML: N/A, the requested URIs are XML namespaces XML: N/A, the requested URIs are XML namespaces
12.5. CoAP Content-Format Registration 12.5. CoAP Content-Format Registration
IANA is requested to assign CoAP Content-Format IDs for the SenML IANA has assigned CoAP Content-Format IDs for the SenML media types
media types in the "CoAP Content-Formats" sub-registry, within the in the "CoAP Content-Formats" subregistry within the "Constrained
"CoRE Parameters" registry [RFC7252]. IDs for the JSON, CBOR, and RESTful Environments (CoRE) Parameters" registry [RFC7252]. IDs for
EXI Content-Formats are assigned from the "Expert Review" (0-255) the JSON, CBOR, and EXI Content-Formats have been assigned in the
range and for the XML Content-Format from the "IETF Review or IESG 0-255 range (Expert Review), and IDs for the XML Content-Formats have
Approval" range. The assigned IDs are shown in Table 8. been assigned in the 256-9999 range (IETF Review or IESG Approval).
The assigned IDs are shown in the table below:
+-------------------------+----------+---------+-----------+ +-------------------------+----------+-----+-----------+
| Media type | Encoding | ID | Reference | | Media Type | Encoding | ID | Reference |
+-------------------------+----------+---------+-----------+ +-------------------------+----------+-----+-----------+
| application/senml+json | - | TBD:110 | RFC-AAAA | | application/senml+json | - | 110 | RFC 8428 |
| application/sensml+json | - | TBD:111 | RFC-AAAA | | application/sensml+json | - | 111 | RFC 8428 |
| application/senml+cbor | - | TBD:112 | RFC-AAAA | | application/senml+cbor | - | 112 | RFC 8428 |
| application/sensml+cbor | - | TBD:113 | RFC-AAAA | | application/sensml+cbor | - | 113 | RFC 8428 |
| application/senml-exi | - | TBD:114 | RFC-AAAA | | application/senml-exi | - | 114 | RFC 8428 |
| application/sensml-exi | - | TBD:115 | RFC-AAAA | | application/sensml-exi | - | 115 | RFC 8428 |
| application/senml+xml | - | TBD:310 | RFC-AAAA | | application/senml+xml | - | 310 | RFC 8428 |
| application/sensml+xml | - | TBD:311 | RFC-AAAA | | application/sensml+xml | - | 311 | RFC 8428 |
+-------------------------+----------+---------+-----------+ +-------------------------+----------+-----+-----------+
Table 8: CoAP Content-Format IDs Table 8: CoAP Content-Format IDs
13. Security Considerations 13. Security Considerations
Sensor data presented with SenML can contain a wide range of Sensor data presented with SenML can contain a wide array of
information ranging from information that is very public, such as the information that ranges from very public (such as the outside
outside temperature in a given city, to very private information that temperature in a given city) to very private (such as patient health
requires integrity and confidentiality protection, such as patient information that requires integrity and confidentiality protection).
health information. When SenML is used for configuration or When SenML is used for configuration or actuation, it can be used to
actuation, it can be used to change the state of systems and also change the state of systems and also impact the physical world, e.g.,
impact the physical world, e.g., by turning off a heater or opening a by turning off a heater or opening a lock. Malicious use of SenML to
lock. change system state could have severe consequences, potentially
including violation of physical security, property damage, and even
loss of life.
The SenML formats alone do not provide any security and instead rely SenML formats alone do not provide any security and instead rely on
on the protocol that carries them to provide security. Applications the protocol that carries them to provide security. Applications
using SenML need to look at the overall context of how these formats using SenML need to look at the overall context of how these formats
will be used to decide if the security is adequate. In particular will be used to decide if the security is adequate. In particular,
for sensitive sensor data and actuation use it is important to ensure for sensitive sensor data and actuation use, it is important to
that proper security mechanisms are used to provide, e.g., ensure that proper security mechanisms are used to provide, e.g.,
confidentiality, data integrity, and authentication as appropriate confidentiality, data integrity, and authentication as appropriate
for the usage. for the usage.
The SenML formats defined by this specification do not contain any SenML formats defined by this specification do not contain any
executable content. However, future extensions could potentially executable content. However, future extensions could potentially
embed application specific executable content in the data. embed application-specific executable content in the data.
SenML Records are intended to be interpreted in the context of any SenML Records are intended to be interpreted in the context of any
applicable base values. If records become separated from the record applicable base values. If Records become separated from the Record
that establishes the base values, the data will be useless or, worse, that establishes the base values, the data will be useless or, worse,
wrong. Care needs to be taken in keeping the integrity of a Pack wrong. Care needs to be taken in keeping the integrity of a Pack
that contains unresolved SenML Records (see Section 4.6). that contains unresolved SenML Records (see Section 4.6).
See also Section 14. See also Section 14.
14. Privacy Considerations 14. Privacy Considerations
Sensor data can range from information with almost no privacy Sensor data can range from information with almost no privacy
considerations, such as the current temperature in a given city, to considerations, such as the current temperature in a given city, to
highly sensitive medical or location data. This specification highly sensitive medical or location data. This specification
provides no security protection for the data but is meant to be used provides no security protection for the data but is meant to be used
inside another container or transfer protocol such as S/MIME inside another container or transfer protocol such as S/MIME
[RFC5751] or HTTP with TLS [RFC2818] that can provide integrity, [RFC5751] or HTTP with TLS [RFC2818] that can provide integrity,
confidentiality, and authentication information about the source of confidentiality, and authentication information about the source of
the data. the data.
The name fields need to uniquely identify the sources or destinations The Name fields need to uniquely identify the sources or destinations
of the values in a SenML Pack. However, the use of long-term stable of the values in a SenML Pack. However, the use of long-term stable
unique identifiers can be problematic for privacy reasons [RFC6973], and unique identifiers can be problematic for privacy reasons
depending on the application and the potential of these identifiers [RFC6973], depending on the application and the potential of these
to be used in correlation with other information. They should be identifiers to be used in correlation with other information. They
used with care or avoided as for example described for IPv6 addresses should be used with care or avoided, for example, as described for
in [RFC7721]. IPv6 addresses in [RFC7721].
15. Acknowledgement
We would like to thank Alexander Pelov, Alexey Melnikov, Andrew
McClure, Andrew McGregor, Bjoern Hoehrmann, Christian Amsuess,
Christian Groves, Daniel Peintner, Jan-Piet Mens, Jim Schaad, Joe
Hildebrand, John Klensin, Karl Palsson, Lennart Duhrsen, Lisa
Dusseault, Lyndsay Campbell, Martin Thomson, Michael Koster, Peter
Saint-Andre, Roni Even, and Stephen Farrell, for their review
comments.
16. References 15. References
16.1. Normative References 15.1. Normative References
[BIPM] Bureau International des Poids et Mesures, "The [BIPM] Bureau International des Poids et Mesures, "The
International System of Units (SI)", 8th edition, 2006. International System of Units (SI)", 8th Edition, 2006.
[IEEE.754.1985] [IEEE.754] IEEE, "Standard for Binary Floating-Point Arithmetic",
Institute of Electrical and Electronics Engineers, IEEE Standard 754.
"Standard for Binary Floating-Point Arithmetic",
IEEE Standard 754, August 1985.
[NIST811] Thompson, A. and B. Taylor, "Guide for the Use of the [NIST811] Thompson, A. and B. Taylor, "Guide for the Use of the
International System of Units (SI)", NIST Special International System of Units (SI)", NIST Special
Publication 811, 2008. Publication 811, DOI 10.6028/NIST.SP.811e2008, March 2008.
[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>.
[RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO [RFC3629] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November 10646", STD 63, RFC 3629, DOI 10.17487/RFC3629, November
2003, <https://www.rfc-editor.org/info/rfc3629>. 2003, <https://www.rfc-editor.org/info/rfc3629>.
skipping to change at page 48, line 10 skipping to change at page 50, line 24
[RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", STD 90, RFC 8259, Interchange Format", STD 90, RFC 8259,
DOI 10.17487/RFC8259, December 2017, DOI 10.17487/RFC8259, December 2017,
<https://www.rfc-editor.org/info/rfc8259>. <https://www.rfc-editor.org/info/rfc8259>.
[RNC] ISO/IEC, "Information technology -- Document Schema [RNC] ISO/IEC, "Information technology -- Document Schema
Definition Language (DSDL) -- Part 2: Regular-grammar- Definition Language (DSDL) -- Part 2: Regular-grammar-
based validation -- RELAX NG", ISO/IEC 19757-2, Annex based validation -- RELAX NG", ISO/IEC 19757-2, Annex
C: RELAX NG Compact syntax, December 2008. C: RELAX NG Compact syntax, December 2008.
[TIME_T] The Open Group Base Specifications, "Vol. 1: Base [TIME_T] The Open Group Base Specifications, "Open Group Standard -
Definitions, Issue 7", Section 4.15 'Seconds Since the Vol. 1: Base Definitions, Issue 7", Section 4.16, "Seconds
Epoch', IEEE Std 1003.1, 2013 Edition, 2013, Since the Epoch", IEEE Standard 1003.1, 2018,
<http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/ <http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/
V1_chap04.html#tag_04_15>. V1_chap04.html#tag_04_16>.
[W3C.REC-exi-20140211] [W3C.REC-exi-20140211]
Schneider, J., Kamiya, T., Peintner, D., and R. Kyusakov, Schneider, J., Kamiya, T., Peintner, D., and R. Kyusakov,
"Efficient XML Interchange (EXI) Format 1.0 (Second "Efficient XML Interchange (EXI) Format 1.0 (Second
Edition)", World Wide Web Consortium Recommendation REC- Edition)", W3C Recommendation REC-exi-20140211, February
exi-20140211, February 2014, 2014, <http://www.w3.org/TR/2014/REC-exi-20140211>.
<http://www.w3.org/TR/2014/REC-exi-20140211>.
[W3C.REC-xml-20081126] [W3C.REC-xml-20081126]
Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and Bray, T., Paoli, J., Sperberg-McQueen, M., Maler, E., and
F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth F. Yergeau, "Extensible Markup Language (XML) 1.0 (Fifth
Edition)", World Wide Web Consortium Recommendation REC- Edition)", W3C Recommendation REC-xml-20081126, November
xml-20081126, November 2008, 2008, <http://www.w3.org/TR/2008/REC-xml-20081126>.
<http://www.w3.org/TR/2008/REC-xml-20081126>.
[W3C.REC-xmlschema-1-20041028] [W3C.REC-xmlschema-1-20041028]
Thompson, H., Beech, D., Maloney, M., and N. Mendelsohn, Thompson, H., Beech, D., Maloney, M., and N. Mendelsohn,
"XML Schema Part 1: Structures Second Edition", World Wide "XML Schema Part 1: Structures Second Edition", W3C
Web Consortium Recommendation REC-xmlschema-1-20041028, Recommendation REC-xmlschema-1-20041028, October 2004,
October 2004,
<http://www.w3.org/TR/2004/REC-xmlschema-1-20041028>. <http://www.w3.org/TR/2004/REC-xmlschema-1-20041028>.
[XPointerElement] [XPointerElement]
Grosso, P., Maler, E., Marsh, J., and N. Walsh, "XPointer Grosso, P., Maler, E., Marsh, J., and N. Walsh, "XPointer
element() Scheme", W3C Recommendation REC-xptr-element, element() Scheme", W3C Recommendation REC-xptr-element,
March 2003, March 2003,
<https://www.w3.org/TR/2003/REC-xptr-element-20030325/>. <https://www.w3.org/TR/2003/REC-xptr-element-20030325/>.
[XPointerFramework] [XPointerFramework]
Grosso, P., Maler, E., Marsh, J., and N. Walsh, "XPointer Grosso, P., Maler, E., Marsh, J., and N. Walsh, "XPointer
Framework", W3C Recommendation REC-XPointer-Framework, Framework", W3C Recommendation REC-XPointer-Framework,
March 2003, March 2003,
<http://www.w3.org/TR/2003/REC-xptr-framework-20030325/>. <http://www.w3.org/TR/2003/REC-xptr-framework-20030325/>.
16.2. Informative References 15.2. Informative References
[AN1796] Linke, B., "Overview of 1-Wire Technology and Its Use", [AN1796] Linke, B., "Overview of 1-Wire Technology and Its Use",
June 2008, Maxim Integrated, Tutorial 1796, June 2008,
<http://pdfserv.maximintegrated.com/en/an/AN1796.pdf>. <http://pdfserv.maximintegrated.com/en/an/AN1796.pdf>.
[I-D.ietf-cbor-cddl] [CDDL-CBOR]
Birkholz, H., Vigano, C., and C. Bormann, "Concise data Birkholz, H., Vigano, C., and C. Bormann, "Concise data
definition language (CDDL): a notational convention to definition language (CDDL): a notational convention to
express CBOR data structures", draft-ietf-cbor-cddl-02 express CBOR and JSON data structures", Work in Progress,
(work in progress), February 2018. draft-ietf-cbor-cddl-05, August 2018.
[I-D.ietf-core-dev-urn] [DEVICE-URN]
Arkko, J., Jennings, C., and Z. Shelby, "Uniform Resource Arkko, J., Jennings, C., and Z. Shelby, "Uniform Resource
Names for Device Identifiers", draft-ietf-core-dev-urn-01 Names for Device Identifiers", Work in Progress,
(work in progress), March 2018. draft-ietf-core-dev-urn-02, July 2018.
[I-D.ietf-core-interfaces]
Shelby, Z., Vial, M., Koster, M., Groves, C., Zhu, J., and
B. Silverajan, "Reusable Interface Definitions for
Constrained RESTful Environments", draft-ietf-core-
interfaces-11 (work in progress), March 2018.
[IEEE802.1as-2011] [IEEE802.1AS]
IEEE, "IEEE Standard for Local and Metropolitan Area IEEE, "IEEE Standard for Local and Metropolitan Area
Networks - Timing and Synchronization for Time-Sensitive Networks - Timing and Synchronization for Time-Sensitive
Applications in Bridged Local Area Networks", 2011. Applications in Bridged Local Area Networks", IEEE
Standard 802.1AS.
[IEEE802.1ba-2011] [IEEE802.1BA]
IEEE, "IEEE Standard for Local and metropolitan area IEEE, "IEEE Standard for Local and metropolitan area
networks--Audio Video Bridging (AVB) Systems", 2011. networks--Audio Video Bridging (AVB) Systems", IEEE
Standard 802.1BA.
[ISO-80000-5] [ISO-80000-5]
"Quantities and units - Part 5: Thermodynamics", ISO, "Quantities and units - Part 5: Thermodynamics",
ISO 80000-5, Edition 1.0, May 2007. ISO 80000-5, Edition 1.0, May 2007.
[RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818, [RFC2818] Rescorla, E., "HTTP Over TLS", RFC 2818,
DOI 10.17487/RFC2818, May 2000, DOI 10.17487/RFC2818, May 2000,
<https://www.rfc-editor.org/info/rfc2818>. <https://www.rfc-editor.org/info/rfc2818>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66, Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005, RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/info/rfc3986>. <https://www.rfc-editor.org/info/rfc3986>.
skipping to change at page 51, line 14 skipping to change at page 53, line 14
[RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy [RFC7721] Cooper, A., Gont, F., and D. Thaler, "Security and Privacy
Considerations for IPv6 Address Generation Mechanisms", Considerations for IPv6 Address Generation Mechanisms",
RFC 7721, DOI 10.17487/RFC7721, March 2016, RFC 7721, DOI 10.17487/RFC7721, March 2016,
<https://www.rfc-editor.org/info/rfc7721>. <https://www.rfc-editor.org/info/rfc7721>.
[RFC8141] Saint-Andre, P. and J. Klensin, "Uniform Resource Names [RFC8141] Saint-Andre, P. and J. Klensin, "Uniform Resource Names
(URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017, (URNs)", RFC 8141, DOI 10.17487/RFC8141, April 2017,
<https://www.rfc-editor.org/info/rfc8141>. <https://www.rfc-editor.org/info/rfc8141>.
[RID-CoRE]
Shelby, Z., Vial, M., Groves, C., Zhu, J., and B.
Silverajan, Ed., "Reusable Interface Definitions for
Constrained RESTful Environments", Work in Progress,
draft-ietf-core-interfaces-12, June 2018.
[UCUM] Schadow, G. and C. McDonald, "The Unified Code for Units [UCUM] Schadow, G. and C. McDonald, "The Unified Code for Units
of Measure (UCUM)", Regenstrief Institute and Indiana of Measure", Version 2.1, Regenstrief Institute and
University School of Informatics, 2013, the UCUM Organization, November 2017,
<http://unitsofmeasure.org/ucum.html>. <http://unitsofmeasure.org/ucum.html>.
Acknowledgements
We would like to thank Alexander Pelov, Alexey Melnikov, Andrew
McClure, Andrew McGregor, Bjoern Hoehrmann, Christian Amsuess,
Christian Groves, Daniel Peintner, Jan-Piet Mens, Jim Schaad, Joe
Hildebrand, John Klensin, Karl Palsson, Lennart Duhrsen, Lisa
Dusseault, Lyndsay Campbell, Martin Thomson, Michael Koster, Peter
Saint-Andre, Roni Even, and Stephen Farrell, for their review
comments.
Authors' Addresses Authors' Addresses
Cullen Jennings Cullen Jennings
Cisco Cisco
400 3rd Avenue SW 400 3rd Avenue SW
Calgary, AB T2P 4H2 Calgary, AB T2P 4H2
Canada Canada
Email: fluffy@iii.ca Email: fluffy@iii.ca
Zach Shelby Zach Shelby
ARM ARM
150 Rose Orchard 150 Rose Orchard
San Jose 95134 San Jose 95134
USA United States of America
Phone: +1-408-203-9434 Phone: +1-408-203-9434
Email: zach.shelby@arm.com Email: zach.shelby@arm.com
Jari Arkko Jari Arkko
Ericsson Ericsson
Jorvas 02420 Jorvas 02420
Finland Finland
Email: jari.arkko@piuha.net Email: jari.arkko@piuha.net
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