draft-ietf-core-senml-09.txt   draft-ietf-core-senml-10.txt 
Network Working Group C. Jennings Network Working Group C. Jennings
Internet-Draft Cisco Internet-Draft Cisco
Intended status: Standards Track Z. Shelby Intended status: Standards Track Z. Shelby
Expires: December 31, 2017 ARM Expires: January 4, 2018 ARM
J. Arkko J. Arkko
A. Keranen A. Keranen
Ericsson Ericsson
C. Bormann C. Bormann
Universitaet Bremen TZI Universitaet Bremen TZI
June 29, 2017 July 3, 2017
Media Types for Sensor Measurement Lists (SenML) Media Types for Sensor Measurement Lists (SenML)
draft-ietf-core-senml-09 draft-ietf-core-senml-10
Abstract Abstract
This specification defines media types for representing simple sensor This specification defines media types for representing simple sensor
measurements and device parameters in the Sensor Measurement Lists measurements and device parameters in the 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 this media type in protocols such as temperature sensor, could use this media type in protocols such as
skipping to change at page 1, line 44 skipping to change at page 1, line 44
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on December 31, 2017. This Internet-Draft will expire on January 4, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 25 skipping to change at page 2, line 25
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
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 . . . . . . . . . . . . . . . . . . . . . . . . . 5
4. SenML Structure and Semantics . . . . . . . . . . . . . . . . 5 4. SenML Structure and Semantics . . . . . . . . . . . . . . . . 6
4.1. Base attributes . . . . . . . . . . . . . . . . . . . . . 6 4.1. Base Fields . . . . . . . . . . . . . . . . . . . . . . . 6
4.2. Regular attributes . . . . . . . . . . . . . . . . . . . 6 4.2. Regular Fields . . . . . . . . . . . . . . . . . . . . . 6
4.3. Considerations . . . . . . . . . . . . . . . . . . . . . 7 4.3. Considerations . . . . . . . . . . . . . . . . . . . . . 7
4.4. Resolved Records . . . . . . . . . . . . . . . . . . . . 8 4.4. Resolved Records . . . . . . . . . . . . . . . . . . . . 8
4.5. Associating Meta-data . . . . . . . . . . . . . . . . . . 8 4.5. Associating Meta-data . . . . . . . . . . . . . . . . . . 9
4.6. Configuration and Actuation usage . . . . . . . . . . . . 9
5. JSON Representation (application/senml+json) . . . . . . . . 9 5. JSON Representation (application/senml+json) . . . . . . . . 9
5.1. Examples . . . . . . . . . . . . . . . . . . . . . . . . 10 5.1. Examples . . . . . . . . . . . . . . . . . . . . . . . . 10
5.1.1. Single Datapoint . . . . . . . . . . . . . . . . . . 10 5.1.1. Single Datapoint . . . . . . . . . . . . . . . . . . 11
5.1.2. Multiple Datapoints . . . . . . . . . . . . . . . . . 10 5.1.2. Multiple Datapoints . . . . . . . . . . . . . . . . . 11
5.1.3. Multiple Measurements . . . . . . . . . . . . . . . . 11 5.1.3. Multiple Measurements . . . . . . . . . . . . . . . . 12
5.1.4. Resolved Data . . . . . . . . . . . . . . . . . . . . 12 5.1.4. Resolved Data . . . . . . . . . . . . . . . . . . . . 13
5.1.5. Multiple Data Types . . . . . . . . . . . . . . . . . 13 5.1.5. Multiple Data Types . . . . . . . . . . . . . . . . . 14
5.1.6. Collection of Resources . . . . . . . . . . . . . . . 13 5.1.6. Collection of Resources . . . . . . . . . . . . . . . 14
5.1.7. Setting an Actuator . . . . . . . . . . . . . . . . . 14 5.1.7. Setting an Actuator . . . . . . . . . . . . . . . . . 14
6. CBOR Representation (application/senml+cbor) . . . . . . . . 15 6. CBOR Representation (application/senml+cbor) . . . . . . . . 15
7. XML Representation (application/senml+xml) . . . . . . . . . 17 7. XML Representation (application/senml+xml) . . . . . . . . . 17
8. EXI Representation (application/senml+exi) . . . . . . . . . 19 8. EXI Representation (application/senml+exi) . . . . . . . . . 19
9. Fragment Identification Methods . . . . . . . . . . . . . . . 22 9. Fragment Identification Methods . . . . . . . . . . . . . . . 22
9.1. Fragment Identification Examples . . . . . . . . . . . . 22 9.1. Fragment Identification Examples . . . . . . . . . . . . 22
10. Usage Considerations . . . . . . . . . . . . . . . . . . . . 23 10. Usage Considerations . . . . . . . . . . . . . . . . . . . . 23
11. CDDL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 11. CDDL . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25 12. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 25
12.1. Units Registry . . . . . . . . . . . . . . . . . . . . . 25 12.1. Units Registry . . . . . . . . . . . . . . . . . . . . . 25
skipping to change at page 3, line 18 skipping to change at page 3, line 19
12.3.7. senml+exi Media Type Registration . . . . . . . . . 38 12.3.7. senml+exi Media Type Registration . . . . . . . . . 38
12.3.8. sensml+exi Media Type Registration . . . . . . . . . 39 12.3.8. sensml+exi Media Type Registration . . . . . . . . . 39
12.4. XML Namespace Registration . . . . . . . . . . . . . . . 41 12.4. XML Namespace Registration . . . . . . . . . . . . . . . 41
12.5. CoAP Content-Format Registration . . . . . . . . . . . . 41 12.5. CoAP Content-Format Registration . . . . . . . . . . . . 41
13. Security Considerations . . . . . . . . . . . . . . . . . . . 41 13. Security Considerations . . . . . . . . . . . . . . . . . . . 41
14. Privacy Considerations . . . . . . . . . . . . . . . . . . . 41 14. Privacy Considerations . . . . . . . . . . . . . . . . . . . 41
15. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 42 15. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 42
16. References . . . . . . . . . . . . . . . . . . . . . . . . . 42 16. References . . . . . . . . . . . . . . . . . . . . . . . . . 42
16.1. Normative References . . . . . . . . . . . . . . . . . . 42 16.1. Normative References . . . . . . . . . . . . . . . . . . 42
16.2. Informative References . . . . . . . . . . . . . . . . . 43 16.2. Informative References . . . . . . . . . . . . . . . . . 43
Appendix A. Links Extension . . . . . . . . . . . . . . . . . . 44 Appendix A. Links Extension . . . . . . . . . . . . . . . . . . 45
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 45 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 45
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
new media types for carrying simple sensor information in a protocol new media types for carrying simple sensor information in a protocol
such as HTTP or CoAP. This format was designed so that processors such as HTTP or CoAP. This format was designed so that processors
with very limited capabilities could easily encode a sensor with very limited capabilities could easily encode a sensor
measurement into the media type, while at the same time a server measurement into the media type, while at the same time a server
skipping to change at page 3, line 47 skipping to change at page 3, line 48
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 tries
to make that a fairly minimal set of auxiliary information for to make that a fairly minimal set of auxiliary information for
efficiency reason. Other information about the sensor can be efficiency reason. 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 CoRE Link Format
[RFC6690]. [RFC6690].
SenML is defined by a data model for measurements and simple meta- SenML is defined by a data model for measurements and simple meta-
data about measurements and devices. The data is structured as a data about measurements and devices. The data is structured as a
single array that contains a series of SenML Records which can each single array that contains a series of SenML Records which can each
contain attributes such as an unique identifier for the sensor, the contain fields such as an unique identifier for the sensor, the time
time the measurement was made, the unit the measurement is in, and the measurement was made, the unit the measurement is in, and the
the current value of the sensor. Serializations for this data model current value of the sensor. Serializations for this data model are
are defined for JSON [RFC7159], CBOR [RFC7049], XML, and Efficient defined for JSON [RFC7159], CBOR [RFC7049], XML, and Efficient XML
XML Interchange (EXI) [W3C.REC-exi-20140211]. Interchange (EXI) [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
skipping to change at page 4, line 36 skipping to change at page 4, line 38
measurements to be batched into a single HTTP or CoAP request. This measurements to be batched into a single HTTP or CoAP request. This
"batch" upload capability allows the server side to efficiently "batch" upload capability allows the server side to efficiently
support a large number of devices. It also conveniently supports support a large number of devices. It also conveniently supports
batch transfers from proxies and storage devices, even in situations batch transfers from proxies and storage devices, even in situations
where the sensor itself sends just a single data item at a time. The where the sensor itself sends just a single data item at a time. The
multiple measurements could be from multiple related sensors or from multiple measurements could be from multiple related sensors or from
the same sensor but at different times. 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 in the "v" tag, the time of a The value of a measurement is given by the "v" field, the time of a
measurement is in the "t" tag, the "n" tag has a unique sensor name, measurement is in the "t" field, the "n" field has a unique sensor
and the unit of the measurement is carried in the "u" tag. 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"
tag 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 which
is simply a string that is prepended to the Name field of all 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" tag and the "n" In the above example the Base Name is in the "bn" field and the "n"
tags in each Record are the empty string so they are omitted. fields in each Record are the empty string 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 supports
absolute and relative times. Time is represented in floating point absolute and relative times. Time is represented in floating point
as seconds and values greater than zero represent an absolute time as seconds and values greater than zero represent an absolute time
relative to the Unix epoch while values of 0 or less represent a relative to the Unix epoch while values of 0 or less represent a
relative time in the past from the current time. A simple sensor relative time in the past from the current time. A simple sensor
with no absolute wall clock time might take a measurement every with no absolute wall clock time might take a measurement every
second, batch up 60 of them, and then send the batch to a server. It second, batch up 60 of them, and then send the batch to a server. It
would include the relative time each measurement was made compared to would include the relative time each measurement was made compared to
the time the batch was sent in each SenML Record. The server might the time the batch was sent in each SenML Record. The server might
skipping to change at page 5, line 42 skipping to change at page 5, line 44
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
[RFC2119]. [RFC2119].
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 fields (e.g., "v" for "value").
SenML Field: A component of a record that associates a value to a
SenML Label for this record.
This document uses the terms "attribute" and "tag" where they occur
with the underlying technologies (XML, CBOR [RFC7049], and Link
Format [RFC6690]), not for SenML concepts per se. Note that
"attribute" has been widely used previously as a synonym for SenML
"field", though.
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 attributes described below. There are two SenML Records with several fields described below. There are two
kind of attributes: base and regular. The base attributes can be kinds of fields: base and regular. The base fields can be included
included in any SenML Record and they apply to the entries in the in any SenML Record and they apply to the entries in the Record.
Record. Each base attribute also applies to all Records after it up Each base field also applies to all Records after it up to, but not
to, but not including, the next Record that has that same base including, the next Record that has that same base field. All base
attribute. All base attributes are optional. Regular attributes can fields are optional. Regular fields can be included in any SenML
be included in any SenML Record and apply only to that Record. Record and apply only to that Record.
4.1. Base attributes 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 Unit
(if any) is used. (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 attribute is an Version: Version number of media type format. This field is an
optional positive integer and defaults to 5 if not present. [RFC optional positive integer and defaults to 5 if not present. [RFC
Editor: change the default value to 10 when this specification is Editor: change the default value to 10 when this specification is
published as an RFC and remove this note] published as an RFC and remove this note]
4.2. Regular attributes 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 attribute, this must result in a globally unique identifier Name field, this must result in a globally unique identifier for
for the resource. The name is optional, if the Base Name is the resource. The name is optional, if the Base Name is present.
present. If the name is missing, Base Name must uniquely identify If the name is missing, Base Name must uniquely identify the
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: Units for a measurement value. Optional. Unit: Units 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 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 Value").
Exactly one value field MUST appear unless there is Sum field in Exactly one value field MUST appear unless there is Sum field in
which case it is allowed to have no Value field. which case it is allowed to have no Value field.
Sum: Integrated sum of the values over time. Optional. This Sum: Integrated sum of the values over time. Optional. This field
attribute is in the units specified in the Unit value multiplied is in the units specified in the Unit value multiplied by seconds.
by seconds.
Time: Time when value was recorded. Optional. Time: Time when value was recorded. Optional.
Update Time: An optional time in seconds that represents the maximum Update Time: An optional 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. This can be used to detect the failure of sensors or measurement. This can be used to detect the failure of sensors or
communications path from the sensor. communications path from the sensor.
4.3. Considerations 4.3. Considerations
The SenML format can be extended with further custom attributes. The SenML format can be extended with further custom fields. Both
Both new base and regular attributes are allowed. See Section 12.2 new base and regular fields are allowed. See Section 12.2 for
for details. Implementations MUST ignore attributes they don't details. Implementations MUST ignore fields they don't recognize
recognize unless that attribute has a label name that ends with the unless that field has a label name that ends with the '_' character
'_' character in which case an error MUST be generated. in which case an error MUST be generated.
Systems reading one of the objects MUST check for the Version All SenML Records in a Pack MUST have the same version number. This
attribute. If this value is a version number larger than the version is typically done by adding a Base Version field to only the first
which the system understands, the system SHOULD NOT use this object. Record in the Pack.
This allows the version number to indicate that the object contains
mandatory to understand attributes. New version numbers can only be Systems reading one of the objects MUST check for the Version field.
If this value is a version number larger than the version which the
system understands, the system SHOULD NOT use this object. This
allows the version number to indicate that the object contains
mandatory to understand fields. New version numbers can only be
defined in an RFC that updates this specification or it successors. defined in an RFC that updates this specification or it successors.
The Name value is concatenated to the Base Name value to get the name The Name value is concatenated to the Base Name value to get the name
of the sensor. The resulting name needs to uniquely identify and of the sensor. The resulting name needs to uniquely identify and
differentiate the sensor from all others. It is RECOMMENDED that the differentiate the sensor from all others. It is RECOMMENDED that the
full names are represented as URIs [RFC3986] or URNs [RFC2141]. One full names are represented as URIs [RFC3986] or URNs [RFC2141]. One
way to create a unique name is to include some bit string that has way to create a unique name is to include some bit string that has
guaranteed uniqueness (such as a 1-wire address) that is assigned to guaranteed uniqueness (such as a 1-wire address) that is assigned to
the device. Some of the examples in this draft use the device URN the device. Some of the examples in this draft use the device URN
type as specified in [I-D.arkko-core-dev-urn]. UUIDs [RFC4122] are type as specified in [I-D.arkko-core-dev-urn]. UUIDs [RFC4122] are
another way to generate a unique name. Note that long-term stable another way to generate a unique name. Note that long-term stable
unique identifiers are problematic for privacy reasons and should be unique identifiers are problematic for privacy reasons and should be
used with care or avoided as described in [RFC7721]. used with care or avoided as described in [RFC7721].
The resulting concatenated name MUST consist only of characters out The resulting concatenated name MUST consist only of characters out
of the set "A" to "Z", "a" to "z", "0" to "9", "-", ":", ".", or "_" of the set "A" to "Z", "a" to "z", "0" to "9", "-", ":", ".", "/", or
and it MUST start with a character out of the set "A" to "Z", "a" to "_" and it MUST start with a character out of the set "A" to "Z", "a"
"z", or "0" to "9". This restricted character set was chosen so that to "z", or "0" to "9". This restricted character set was chosen so
these names can be directly used as in other types of URI including that these names can be directly used as in other types of URI
segments of an HTTP path with no special encoding and can be directly including segments of an HTTP path with no special encoding and can
used in many databases and analytic systems. [RFC5952] contains be directly used in many databases and analytic systems. [RFC5952]
advice on encoding an IPv6 address in a name. contains advice on encoding an IPv6 address in a name.
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. no Unit and no Base Unit is allowed.
If either the Base Time or Time value is missing, the missing If either the Base Time or Time value is missing, the missing field
attribute is considered to have a value of zero. The Base Time and is considered to have a value of zero. The Base Time and Time values
Time values are added together to get the time of measurement. A are added together to get the time of measurement. A time of zero
time of zero indicates that the sensor does not know the absolute indicates that the sensor does not know the absolute time and the
time and the measurement was made roughly "now". A negative value is measurement was made roughly "now". A negative value is used to
used to indicate seconds in the past from roughly "now". A positive indicate seconds in the past from roughly "now". A positive value is
value is used to indicate the number of seconds, excluding leap used to indicate the number of seconds, excluding leap seconds, since
seconds, since the start of the year 1970 in UTC. the start of the year 1970 in UTC.
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
attribute is considered to have a value of zero. The Base Sum and field is considered to have a value of zero. The Base Sum and Sum
Sum values are added together to get the sum of measurement. If values are added together to get the sum of measurement. If neither
neither the Base Sum or Sum are present, then the measurement does the Base Sum or Sum are present, then the measurement does not have a
not have a sum value. sum value.
If the Base Value or Value is not present, the missing attribute(s) If the Base Value or Value is not present, the missing field(s) are
are 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
attributes to provide better information about the statistical fields to provide better information about the statistical properties
properties of the measurement. of the measurement.
4.4. Resolved Records 4.4. 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. other formats.
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 and has no relative times, but the base values of the any base values and has no relative times, but the base values of the
SenML Pack (if any) are applied to the Record. That is, name and SenML Pack (if any) are applied to the Record. That is, name and
base name are concatenated, base time is added to the time of the base name are concatenated, base time is added to the time of the
Record, if the Record did not contain Unit the Base Unit is applied Record, if the Record did not contain Unit the Base Unit is applied
to the record, etc. In addition the records need to be in to the record, etc. In addition the records need to be in
chronological order. An example of this is show in Section 5.1.4. chronological order. An example of this is show in Section 5.1.4.
Future specification that defines new base attributes need to specify Future specification that defines new base fields need to specify how
how the attribute is resolved. the field is resolved.
4.5. Associating Meta-data 4.5. Associating Meta-data
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 meta-data about the device, object or sensors. Instead, it is
assumed that this meta-data is carried out of band. For web assumed that this meta-data is carried out of band. For web
resources using SenML Packs, this meta-data can be made available resources using SenML Packs, this meta-data can be made available
using the CoRE Link Format [RFC6690]. The most obvious use of this using the CoRE Link Format [RFC6690]. The most obvious use of this
link format is to describe that a resource is available in a SenML link format is to describe that a resource is available in a SenML
format in the first place. The relevant media type indicator is format in the first place. The relevant media type indicator is
included in the Content-Type (ct=) attribute. included in the Content-Type (ct=) link attribute (which is defined
for the Link Format in Section 7.2.1 of [RFC7252]).
4.6. Configuration and Actuation usage
SenML can also be used for configuring parameters and controlling
actuators. When a SenML Pack is sent (e.g., using a HTTP/CoAP POST
or PUT method) and the semantics of the target are such that SenML is
interpreted as configuration/actuation, SenML Records are interpreted
as a request to change the values of given (sub)resources (given as
names) to given values at the given time(s).
5. JSON Representation (application/senml+json) 5. JSON Representation (application/senml+json)
The SenML labels (JSON object member names) shown in Table 1 are used For the SenML fields shown in Table 1, the SenML labels are used as
in JSON SenML Record attributes. the JSON object member names within JSON objects representing the
JSON SenML Records.
+---------------+-------+---------+ +---------------+-------+---------+
| Name | label | Type | | Name | label | 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 | | Version | bver | Number |
skipping to change at page 9, line 35 skipping to change at page 10, line 28
| Boolean Value | vb | Boolean | | Boolean Value | vb | Boolean |
| Data Value | vd | String | | Data Value | vd | String |
| Value Sum | s | Number | | Value Sum | s | Number |
| Time | t | Number | | Time | t | Number |
| Update Time | ut | Number | | Update Time | ut | Number |
| Link | l | String | | Link | l | String |
+---------------+-------+---------+ +---------------+-------+---------+
Table 1: JSON SenML Labels Table 1: JSON SenML Labels
The root content consists of an array with one JSON object for each The root JSON value consists of an array with one JSON object for
SenML Record. All the fields in the above table MAY occur in the each SenML Record. All the fields in the above table MAY occur in
records with the type specified in the table. the records with member values of the type specified in the table.
Only the UTF-8 form of JSON is allowed. Characters in the String Only the UTF-8 form of JSON is allowed. Characters in the String
Value are encoded using the escape sequences defined in [RFC7159]. Value are encoded using the escape sequences defined in [RFC7159].
Octets in the Data Value are base64 encoded with URL safe alphabet as Octets in the Data Value are base64 encoded with URL safe alphabet as
defined in Section 5 of [RFC4648]. 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 an IEEE double
precision floating point numbers [IEEE.754.1985]. The number of precision floating point numbers [IEEE.754.1985]. The number of
significant digits in any measurement is not relevant, so a reading significant digits in any measurement is not relevant, so a reading
of 1.1 has exactly the same semantic meaning as 1.10. If the value of 1.1 has exactly the same semantic meaning as 1.10. If the value
has an exponent, the "e" MUST be in lower case. The mantissa SHOULD has an exponent, the "e" MUST be in lower case. The mantissa SHOULD
be less than 19 characters long and the exponent SHOULD be less than be less than 19 characters long and the exponent SHOULD be less than
5 characters long. This allows time values to have better than micro 5 characters long. This allows time values to have better than micro
second precision over the next 100 years. second precision over the next 100 years.
skipping to change at page 13, line 43 skipping to change at page 14, line 14
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":"nfv-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 another devices. The that aggregates multiple measurements from another 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 a result, a temperature and humidity measurement as well as the as 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. Note that the last record would use the
Base Name from the 3rd record but the Base Time from the first Base Name from the 3rd record but the Base Time from the first
record. 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", {"bn":"2001:db8::1/","n":"temperature","u":"Cel","v":12.3},
"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 show 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 which 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.
skipping to change at page 14, line 32 skipping to change at page 15, line 4
current set point of a typical residential thermostat which has a current set point of a typical residential thermostat which 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 802.1BA network that can guarantee assumed that the lights are on a network that can guarantee delivery
delivery of the messages to the two lights within 15 ms and uses of the messages to the two lights within 15 ms (e.g. a network using
802.1AS for time synchronization. The controller has set the time of 802.1BA [IEEE802.1ba-2011] and 802.1AS [IEEE802.1as-2011] for time
the lights coming on to 20 ms in the future from the current time. synchronization). The controller has set the time of the lights
This allows both lights to receive the message, wait till that time, coming on to 20 ms in the future from the current time. This allows
then apply the switch command so that both lights come on at the same both lights to receive the message, wait till that time, then apply
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 non The following shows two lights being turned off using a non
deterministic network that has a high odds of delivering a message in deterministic network that has a high odds of delivering a message in
less than 100 ms and uses NTP for time synchronization. The current less than 100 ms and uses NTP for time synchronization. The current
time is 1320078429. The user has just turned off a light switch time is 1320078429. The user has just turned off a light switch
skipping to change at page 15, line 33 skipping to change at page 16, line 7
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); however
a representation SHOULD be chosen such that when the CBOR value is a representation SHOULD be chosen such that when the CBOR value is
converted back to an IEEE double precision floating point value, converted back to an IEEE double precision floating point value,
it has exactly the same value as the original Number. For the it has exactly the same value as the original Number. For the
version number, only an unsigned integer is allowed. 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 definite length
text string (type 3). Octets in the Data Value are encoded using text string (type 3). Octets in the Data Value are encoded using
a definite length byte string (type 2) . a definite length byte string (type 2).
o For compactness, the CBOR representation uses integers for the map o For compactness, the CBOR representation uses integers for the
keys defined in Table 3. This table is conclusive, i.e., there is labels, as defined in Table 3. This table is conclusive, i.e.,
no intention to define any additional integer map keys; any there is no intention to define any additional integer map keys;
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 convert also
all future labels without needing to update implementations. all future labels without needing to update implementations.
+---------------+-------+------------+ +---------------+-------+------------+
| Name | Label | CBOR Label | | Name | Label | CBOR Label |
+---------------+-------+------------+ +---------------+-------+------------+
| Version | bver | -1 | | Version | bver | -1 |
| Base Name | bn | -2 | | Base Name | bn | -2 |
| Base Time | bt | -3 | | Base Time | bt | -3 |
| Base Units | bu | -4 | | Base Units | bu | -4 |
skipping to change at page 16, line 29 skipping to change at page 16, line 40
| Value Sum | s | 5 | | Value 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 |
| Link | l | 9 | | Link | l | 9 |
+---------------+-------+------------+ +---------------+-------+------------+
Table 3: CBOR representation: integers for map keys Table 3: 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 an CBOR indefinite length array while for the records SHOULD be a CBOR indefinite length array while for
non streaming SenML, a definite length array MUST be used. non-streaming SenML, a definite length array 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 17, line 29 skipping to change at page 17, line 44
<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 tag that contains a The SenML Stream is represented as a sensml element that contains a
series of senml tags for each SenML Record. The SenML Fields are series of senml elements for each SenML Record. The SenML fields are
represents as XML attributes. The following table shows the mapping represented as XML attributes. For each field defined in this
of the SenML labels, which are used for the attribute name, to the document, the following table shows the SenML labels, which are used
attribute types used in the XML senml tags. for the XML attribute name, as well as the according restrictions on
the XML attribute values ("type") as used in the XML senml elements.
+---------------+-------+---------+ +---------------+-------+---------+
| Name | Label | Type | | Name | Label | 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 |
skipping to change at page 21, line 39 skipping to change at page 21, line 39
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 07 1d 75 72 6e 3a 64 65 76 |..H.l ...urn:dev| 0000 a0 00 48 80 6c 20 01 07 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 devices that only generates this one EXI A small temperature sensor device that only generates this one EXI
file does not really need an full EXI implementation. It can simply file does not really need an 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
0x20 and going to byte 0x2F with it's device ID, and replacing the 0x20 and going to byte 0x2F with it's device ID, and replacing the
value "0xe7 0x01" at location 0x37 and 0x38 with the current value "0xe7 0x01" at location 0x37 and 0x38 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 bytes at is set to low 7 bits
skipping to change at page 22, line 21 skipping to change at page 22, line 21
Fragment Identifier to a single record, or a set of records, in a Fragment Identifier to a single record, or a set of records, in a
Pack. The fragment identifier is only interpreted by a client and Pack. The fragment identifier is only interpreted by a client and
does not impact retrieval of a representation. The SenML Fragment does not impact retrieval of a representation. The SenML Fragment
Identification is modeled after CSV Fragment Identifiers [RFC7111]. Identification is modeled after 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 record 1.) 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 "coap://example.com/temp" resource can be
selected with: 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:
skipping to change at page 23, line 21 skipping to change at page 23, line 21
the sum is more useful than the current value. For example, an the sum is more useful than the current value. For example, an
electrical meter that measures the energy a given computer uses will electrical meter that measures the energy a given computer uses will
typically want to measure the cumulative amount of energy used. This typically want to measure the cumulative amount of energy used. This
is less prone to error than reporting the power each second and is less prone to error than reporting the power each second and
trying to have something on the server side sum together all the trying to have something on the server side sum together all the
power measurements. If the network between the sensor and the meter power measurements. If the network between the sensor and the meter
goes down over some period of time, when it comes back up, the goes down over some period of time, when it comes back up, the
cumulative sum helps reflect what happened while the network was cumulative sum helps reflect what happened while the network was
down. A meter like this would typically report a measurement with down. A meter like this would typically report a measurement with
the units set to watts, but it would put the sum of energy used in the units set to watts, but it would put the sum of energy used in
the "s" attribute of the measurement. It might optionally include the "s" field of the measurement. It might optionally include the
the current power in the "v" attribute. current power in the "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.
Implementors are encouraged to report the cumulative sum as well as Implementors 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
skipping to change at page 24, line 17 skipping to change at page 24, line 17
For reference, the JSON and CBOR representations can be described For reference, the JSON and CBOR representations can be described
with the common CDDL [I-D.greevenbosch-appsawg-cbor-cddl] with the common CDDL [I-D.greevenbosch-appsawg-cbor-cddl]
specification in Figure 1. specification in Figure 1.
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, ; Value Sum
? t => numeric, ; Time ? t => numeric, ; Time
? ut => numeric, ; Update Time ? ut => numeric, ; Update Time
? l => tstr, ; Link ? l => tstr, ; Link
? ( v => numeric // ; Numeric Value ? ( v => numeric // ; Numeric Value
vs => tstr // ; String Value vs => tstr // ; String Value
vb => bool // ; Boolean Value vb => bool // ; Boolean Value
skipping to change at page 30, line 15 skipping to change at page 30, line 15
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 character 'b'. Regular labels MUST NOT start with MUST start with character 'b'. Regular labels MUST NOT start with
that character. that character.
Extensions that add a label that is intended for use with XML need to Extensions that add a label that is intended for use with XML need to
create a new RelaxNG scheme that includes all the labels in the IANA create a new RelaxNG scheme that includes all the labels in the IANA
registry. 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 IANA
registry then allocate a new EXI schemaId value. Moving to the next registry and then allocate a new EXI schemaId value. Moving to the
letter in the alphabet is the suggested way to create the new value next letter in the alphabet is the suggested way to create the new
for the EXI schemaId. Any labels with previously blank ID values value for the EXI schemaId. Any labels with previously blank ID
SHOULD be updated in the IANA table to have their ID set to this new values SHOULD be updated in the IANA table to have their ID set to
schemaId value. 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 Registration 12.3. Media Type Registration
The following registrations are done following the procedure The following registrations are done following the procedure
specified in [RFC6838] and [RFC7303]. Clipboard formats are defined specified in [RFC6838] and [RFC7303]. Clipboard formats are defined
for the JSON and XML form of lists but do not make sense for streams for the JSON and XML form of lists but do not make sense for streams
or other formats. or other formats.
skipping to change at page 36, line 19 skipping to change at page 36, line 19
Security considerations: Sensor data can contain a wide range of Security considerations: Sensor data can contain a wide range of
information ranging from information that is very public, such the information ranging from information that is very public, such the
outside temperature in a given city, to very private information that outside temperature in a given city, to very private information that
requires integrity and confidentiality protection, such as patient requires integrity and confidentiality protection, such as patient
health information. This format does not provide any security and health information. This format does not provide any security and
instead relies on the transport protocol that carries it to provide instead relies on the transport protocol that carries it to provide
security. Given applications need to look at the overall context of security. Given applications need to look at the overall context of
how this media type will be used to decide if the security is how this media type will be used to decide if the security is
adequate. adequate.
Interoperability considerations: Applications should ignore any tags Interoperability considerations: Applications should ignore any XML
or attributes that they do not understand. This allows backwards tags or attributes that they do not understand. This allows
compatibility extensions to this specification. The "bver" attribute backwards compatibility extensions to this specification. The "bver"
in the senml tag can be used to ensure the receiver supports a attribute in the senml XML tag can be used to ensure the receiver
minimal level of functionality needed by the creator of the XML. supports a minimal level of functionality needed by the creator of
the XML.
Published specification: RFC-AAAA Published specification: RFC-AAAA
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
skipping to change at page 37, line 35 skipping to change at page 37, line 35
Security considerations: Sensor data can contain a wide range of Security considerations: Sensor data can contain a wide range of
information ranging from information that is very public, such the information ranging from information that is very public, such the
outside temperature in a given city, to very private information that outside temperature in a given city, to very private information that
requires integrity and confidentiality protection, such as patient requires integrity and confidentiality protection, such as patient
health information. This format does not provide any security and health information. This format does not provide any security and
instead relies on the transport protocol that carries it to provide instead relies on the transport protocol that carries it to provide
security. Given applications need to look at the overall context of security. Given applications need to look at the overall context of
how this media type will be used to decide if the security is how this media type will be used to decide if the security is
adequate. adequate.
Interoperability considerations: Applications should ignore any tags Interoperability considerations: Applications should ignore any XML
or attributes that they do not understand. This allows backwards tags or attributes that they do not understand. This allows
compatibility extensions to this specification. The "bver" attribute backwards compatibility extensions to this specification. The "bver"
in the senml tag can be used to ensure the receiver supports a attribute in the senml XML tag can be used to ensure the receiver
minimal level of functionality needed by the creator of the XML. supports a minimal level of functionality needed by the creator of
the XML.
Published specification: RFC-AAAA Published specification: RFC-AAAA
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
skipping to change at page 38, line 47 skipping to change at page 38, line 47
Security considerations: Sensor data can contain a wide range of Security considerations: Sensor data can contain a wide range of
information ranging from information that is very public, such the information ranging from information that is very public, such the
outside temperature in a given city, to very private information that outside temperature in a given city, to very private information that
requires integrity and confidentiality protection, such as patient requires integrity and confidentiality protection, such as patient
health information. This format does not provide any security and health information. This format does not provide any security and
instead relies on the transport protocol that carries it to provide instead relies on the transport protocol that carries it to provide
security. Given applications need to look at the overall context of security. Given applications need to look at the overall context of
how this media type will be used to decide if the security is how this media type will be used to decide if the security is
adequate. adequate.
Interoperability considerations: Applications should ignore any tags Interoperability considerations: Applications should ignore any XML
or attributes that they do not understand. This allows backwards tags or attributes that they do not understand. This allows
compatibility extensions to this specification. The "bver" attribute backwards compatibility extensions to this specification. The "bver"
in the senml tag can be used to ensure the receiver supports a attribute in the senml XML tag can be used to ensure the receiver
minimal level of functionality needed by the creator of the XML. supports a minimal level of functionality needed by the creator of
the XML. Further information on using schemas to guide the EXI can
Further information on using schemas to guide the EXI can be found in be found in RFC-AAAA.
RFC-AAAA.
Published specification: RFC-AAAA Published specification: RFC-AAAA
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
skipping to change at page 40, line 15 skipping to change at page 40, line 15
Security considerations: Sensor data can contain a wide range of Security considerations: Sensor data can contain a wide range of
information ranging from information that is very public, such the information ranging from information that is very public, such the
outside temperature in a given city, to very private information that outside temperature in a given city, to very private information that
requires integrity and confidentiality protection, such as patient requires integrity and confidentiality protection, such as patient
health information. This format does not provide any security and health information. This format does not provide any security and
instead relies on the transport protocol that carries it to provide instead relies on the transport protocol that carries it to provide
security. Given applications need to look at the overall context of security. Given applications need to look at the overall context of
how this media type will be used to decide if the security is how this media type will be used to decide if the security is
adequate. adequate.
Interoperability considerations: Applications should ignore any tags Interoperability considerations: Applications should ignore any XML
or attributes that they do not understand. This allows backwards tags or attributes that they do not understand. This allows
compatibility extensions to this specification. The "bver" attribute backwards compatibility extensions to this specification. The "bver"
in the senml tag can be used to ensure the receiver supports a attribute in the senml XML tag can be used to ensure the receiver
minimal level of functionality needed by the creator of the XML. supports a minimal level of functionality needed by the creator of
Further information on using schemas to guide the EXI can be found in the XML. Further information on using schemas to guide the EXI can
RFC-AAAA. be found in RFC-AAAA.
Published specification: RFC-AAAA Published specification: RFC-AAAA
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
skipping to change at page 44, line 11 skipping to change at page 44, line 11
definition language (CDDL): a notational convention to definition language (CDDL): a notational convention to
express CBOR data structures", draft-greevenbosch-appsawg- express CBOR data structures", draft-greevenbosch-appsawg-
cbor-cddl-10 (work in progress), March 2017. cbor-cddl-10 (work in progress), March 2017.
[I-D.ietf-core-links-json] [I-D.ietf-core-links-json]
Li, K., Rahman, A., and C. Bormann, "Representing Li, K., Rahman, A., and C. Bormann, "Representing
Constrained RESTful Environments (CoRE) Link Format in Constrained RESTful Environments (CoRE) Link Format in
JSON and CBOR", draft-ietf-core-links-json-08 (work in JSON and CBOR", draft-ietf-core-links-json-08 (work in
progress), April 2017. progress), April 2017.
[IEEE802.1as-2011]
IEEE, "IEEE Standard for Local and Metropolitan Area
Networks - Timing and Synchronization for Time-Sensitive
Applications in Bridged Local Area Networks", 2011.
[IEEE802.1ba-2011]
IEEE, "IEEE Standard for Local and metropolitan area
networks--Audio Video Bridging (AVB) Systems", 2011.
[RFC2141] Moats, R., "URN Syntax", RFC 2141, DOI 10.17487/RFC2141, [RFC2141] Moats, R., "URN Syntax", RFC 2141, DOI 10.17487/RFC2141,
May 1997, <http://www.rfc-editor.org/info/rfc2141>. May 1997, <http://www.rfc-editor.org/info/rfc2141>.
[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,
<http://www.rfc-editor.org/info/rfc3986>. <http://www.rfc-editor.org/info/rfc3986>.
[RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally [RFC4122] Leach, P., Mealling, M., and R. Salz, "A Universally
Unique IDentifier (UUID) URN Namespace", RFC 4122, Unique IDentifier (UUID) URN Namespace", RFC 4122,
skipping to change at page 44, line 50 skipping to change at page 45, line 12
RFC 7721, DOI 10.17487/RFC7721, March 2016, RFC 7721, DOI 10.17487/RFC7721, March 2016,
<http://www.rfc-editor.org/info/rfc7721>. <http://www.rfc-editor.org/info/rfc7721>.
[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 (UCUM)", Regenstrief Institute and Indiana
University School of Informatics, 2013, University School of Informatics, 2013,
<http://unitsofmeasure.org/ucum.html>. <http://unitsofmeasure.org/ucum.html>.
Appendix A. Links Extension Appendix A. Links Extension
An attribute to support a link extension for SenML is defined as a A field to support a link extension for SenML is defined as a string
string attribute by this specification. The link extension can be field by this specification. The link extension can be used for
used for additional information about a SenML Record. The definition additional information about a SenML Record. The definition and
and usage of the contents of this value are specified in usage of the contents of this value are specified in
[I-D.ietf-core-links-json]. [I-D.ietf-core-links-json].
For JSON and XML the attribute has a label of "l" and a value that is For JSON and XML the field has a label of "l" and a value that is a
a string. string.
The following shows an example of the links extension. The following shows an example of the links extension.
[ [
{"bn":"urn:dev:ow:10e2073a01080063:","bt":1.320078429e+09, {"bn":"urn:dev:ow:10e2073a01080063:","bt":1.320078429e+09,
"l":"[{\"href\":\"humidity\",\"foo\":\"bar\"}]", "l":"[{\"href\":\"humidity\",\"foo\":\"bar\"}]",
"n":"temperature","u":"Cel","v":27.2}, "n":"temperature","u":"Cel","v":27.2},
{"n":"humidity","u":"%RH","v":80} {"n":"humidity","u":"%RH","v":80}
] ]
 End of changes. 53 change blocks. 
152 lines changed or deleted 188 lines changed or added

This html diff was produced by rfcdiff 1.45. The latest version is available from http://tools.ietf.org/tools/rfcdiff/