One document matched: draft-jennings-senml-08.xml
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<rfc category="std" docName="draft-jennings-senml-08" ipr="trust200902">
<front>
<title abbrev="Sensor Markup">Media Types for Sensor Markup Language
(SENML)</title>
<author fullname="Cullen Jennings" initials="C." surname="Jennings">
<organization>Cisco</organization>
<address>
<postal>
<street>170 West Tasman Drive</street>
<city>San Jose</city>
<region>CA</region>
<code>95134</code>
<country>USA</country>
</postal>
<phone>+1 408 421-9990</phone>
<email>fluffy@cisco.com</email>
</address>
</author>
<author fullname="Zach Shelby" initials="Z" surname="Shelby">
<organization>Sensinode</organization>
<address>
<postal>
<street>Kidekuja 2</street>
<city>Vuokatti</city>
<code>88600</code>
<country>FINLAND</country>
</postal>
<phone>+358407796297</phone>
<email>zach@sensinode.com</email>
</address>
</author>
<author fullname="Jari Arkko" initials="J" surname="Arkko">
<organization>Ericsson</organization>
<address>
<postal>
<street></street>
<city>Jorvas</city>
<code>02420</code>
<country>Finland</country>
</postal>
<email>jari.arkko@piuha.net</email>
</address>
</author>
<date day="20" month="January" year="2012" />
<area>APPS</area>
<abstract>
<t>This specification defines media types for representing simple sensor
measurements and device parameters in the Sensor Markup Language
(SenML). Representations are defined in JavaScript Object Notation
(JSON), eXtensible Markup Language (XML) and Efficient XML Interchange
(EXI), which share the common SenML data model. A simple sensor, such as
a temperature sensor, could use this media type in protocols such as
HTTP or CoAP to transport the measurements of the sensor or to be
configured.</t>
</abstract>
</front>
<middle>
<section title="Overview">
<t>Connecting sensors to the internet is not new, and there have been
many protocols designed to facilitate it. This specification defines new
media types for carrying simple sensor information in a protocol such as
HTTP or CoAP<xref target="I-D.ietf-core-coap"></xref> called the Sensor
Markup Language (SenML). This format was designed so that processors
with very limited capabilities could easily encode a sensor measurement
into the media type, while at the same time a server parsing the data
could relatively efficiently collect a large number of sensor
measurements. There are many types of more complex measurements and
measurements that this media type would not be suitable for. A decision
was made not to carry most of the meta data about the sensor in this
media type to help reduce the size of the data and improve efficiency in
decoding. Instead meta-data about a sensor resource can be described
out-of-band using the CoRE Link Format <xref
target="I-D.ietf-core-link-format"></xref>. The markup language can be
used for a variety of data flow models, most notably data feeds pushed
from a sensor to a collector, and the web resource model where the
sensor is requested as a resource representation (GET
/sensor/temperature).</t>
<t>SenML is defined by a data model for measurements and simple
meta-data about measurements and devices. The data is structured as a
single object (with attributes) that contains an array of entries. Each
entry is an object that has attributes such as a unique identifier for
the sensor, the time the measurement was made, and the current value.
Serializations for this data model are defined for JSON <xref
target="RFC4627"></xref>, XML and Efficient XML Interchange (EXI) <xref
target="W3C.REC-exi-20110310"></xref>.</t>
<t>For example, the following shows a measurement from a temperature
gauge encoded in the JSON syntax.</t>
<figure>
<artwork><![CDATA[{"e":[{ "n": "urn:dev:ow:10e2073a01080063", "v":23.5, "u":"degC" }]}
]]></artwork>
</figure>
<t>In the example above, the array in the object has a single
measurement for a sensor named "urn:dev:ow:10e2073a01080063" with a
temperature of 23.5 degrees Celsius.</t>
</section>
<section title="Requirements and Design Goals">
<t>The design goal is to be able to send simple sensor measurements in
small packets on mesh networks from large numbers of constrained
devices. Keeping the total size under 80 bytes makes this easy to use on
a wireless mesh network. It is always difficult to define what small
code is, but there is a desire to be able to implement this in roughly 1
KB of flash on a 8 bit microprocessor. Experience with Google power
meter and large scale deployments has indicated that the solution needs
to support allowing multiple measurements to be batched into a single
HTTP or CoAP request. This "batch" upload capability allows the server
side to efficiently support a large number of devices. It also
conveniently supports batch transfers from proxies and storage devices,
even in situations where the sensor itself sends just a single data item
at a time. The multiple measurements could be from multiple related
sensors or from the same sensor but at different times.</t>
</section>
<section title="Terminology">
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in <xref
target="RFC2119">RFC 2119</xref>.</t>
</section>
<section anchor="semant" title="Semantics">
<t>Each representation caries a single SenML object that represents a
set of measurements and/or parameters. This object contains several
optional attributes described below and a mandatory array of one or more
entries.</t>
<t><list style="hanging">
<t hangText="Base Name"><vspace blankLines="1" />This is a string
that is prepended to the names found in the entries. This attribute
is optional.<vspace blankLines="1" /></t>
<t hangText="Base Time"><vspace blankLines="1" />A base time that is
added to the time found in an entry. This attribute is
optional.<vspace blankLines="1" /></t>
<t hangText="Base Units"><vspace blankLines="1" />A base unit that
is assumed for all entries, unless otherwise indicated. This
attribute is optional. Acceptable values are specified in <xref
target="sec-units"> </xref>.<vspace blankLines="1" /></t>
<t hangText="Version"><vspace blankLines="1" />Version number of
media type format. This attribute is optional positive integer and
defaults to 1 if not present.<vspace blankLines="1" /></t>
<t hangText="Measurement or Parameter Entries"><vspace
blankLines="1" />Array of values for sensor measurements or other
generic parameters (such as configuration parameters). If present
there must be at least one entry in the array.<vspace
blankLines="1" /></t>
</list></t>
<t>Each array entry contains several attributes, some of which are
optional and some of which are mandatory.</t>
<t><list style="hanging">
<t hangText="Name"><vspace blankLines="1" />Name of the sensor or
parameter. When appended to the Base Name attribute, this must
result in a globally unique identifier for the resource. The name is
optional, if the Base Name is present. If the name is missing Base
Name must uniquely identify the resource. This can be used to
represent a large array of measurements from the same sensor without
having to repeat its identifier on every measurement.<vspace
blankLines="1" /></t>
<t hangText="Units"><vspace blankLines="1" />Units for a measurement
value. Optional, if Base Unit is present or if not required for a
parameter. Acceptable values are specified in <xref
target="sec-units"> </xref>.<vspace blankLines="1" /></t>
<t hangText="Value"><vspace blankLines="1" />Value of the entry.
Optional if a Sum value is present, otherwise required. Values are
represented using three basic data types, Floating point numbers
("v" field for "Value"), Booleans ("bv" for "Boolean Value") and
Strings ("sv" for "String Value"). Exactly one of these three fields
MUST appear.<vspace blankLines="1" /></t>
<t hangText="Sum"><vspace blankLines="1" />Integrated sum of the
values over time. Optional. This attribute is in the units specified
in the Unit value multiplied by seconds.<vspace
blankLines="1" /></t>
<t hangText="Time"><vspace blankLines="1" />Time when value was
recorded. Optional.<vspace blankLines="1" /></t>
<t hangText="Update Time"><vspace blankLines="1" />Update time. A
time in seconds that represents the maximum time before this sensor
will provide an updated reading for a measurement. This can be used
to detect the failure of sensors or communications path from the
sensor. Optional.<vspace blankLines="1" /></t>
</list></t>
<t>The SenML format can be extended with further custom attributes
placed in the base object, or in an entry. Extensions in the base object
pertain to all entries, whereas extensions in an entry object only
pertain to that.</t>
<t>Systems reading one of the objects MUST check for the Version
attribute. 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 attributes. New version numbers can only be
defined in RFC which updates this specification or it successors.</t>
<t>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
differentiate the sensor from all others. If the object is a
representation resulting from the request of a URI <xref
target="RFC3986"></xref>, then in the absence of the Base Name
attribute, this URI is used as the default value of Base Name. Thus in
this case the Name field needs to be unique for that URI, for example an
index or subresource name of sensors handled by the URI.</t>
<t>Alternatively, for objects not related to a URI, a unique name is
required. In any case, it is RECOMMENDED that the full names are
represented as URIs or URNs <xref target="RFC2141"></xref>. One way to
create a unique name is to include a EUI-48 or EUI-64 identifier (A MAC
address) or some other bit string that is 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 type as specified in <xref
target="I-D.arkko-core-dev-urn"></xref>. UUIDs <xref
target="RFC4122"></xref> are another way to generate a unique name.</t>
<t>The resulting concatenated name MUST consist only of characters out
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 "z", or
"0" to "9". This restricted character set was chosen so that these names
can be directly used as in other types of URI including segments of an
HTTP path with no special encoding. <xref target="RFC5952"></xref>
contains advice on encoding an IPv6 address in a name.</t>
<t>If either the Base Time or Time value is missing, the missing
attribute is considered to have a value of zero. The Base Time and Time
values are added together to get the time of measurement. A time of zero
indicates that the sensor does not know the absolute time and the
measurement was made roughly "now". A negative value is used to indicate
seconds in the past from roughly "now". A positive value is used to
indicate the number of seconds, excluding leap seconds, since the start
of the year 1970 in UTC .</t>
<t>Representing the statistical characteristics of measurements can be
very complex. Future specification may add new attributes to provide
better information about the statistical properties of the
measurement.</t>
</section>
<section title="Associating Meta-data">
<t>SenML is designed to carry the minimum dynamic information about
measurements, and for efficiency reasons does not carry more static
meta-data about the device, object or sensors. Instead, it is assumed
that this meta-data is carried out of band. For web resources using
SenML representations, this meta-data can be made available using the
CoRE Link Format <xref target="I-D.ietf-core-link-format"></xref>.</t>
<t>The CoRE Link Format provides a simple way to describe Web Links, and
in particular allows a web server to describe resources it is hosting.
The list of links that a web server has available, can be discovered by
retrieving the /.well-known/core resource, which returns the list of
links in the CoRE Link Format. Each link may contain attributes, for
example title, resource type, interface description and
content-type.</t>
<t>The most obvious use of this link format is to describe that a
resource is available in a SenML format in the first place. The relevant
media type indicator is included in the Content-Type (ct=)
attribute.</t>
<t>Further semantics about a resource can be included in the Resource
Type and Interface Description attributes. The Resource Type (rt=)
attribute is meant to give a semantic meaning to that resource. For
example rt="OutdoorTemperature" would indicate static semantic meaning
in addition to the unit information included in SenML. The Interface
Description (if=) attribute is used to describe the REST interface of a
resource, and may include e.g. a reference to a WADL description <xref
target="WADL"></xref>.</t>
</section>
<section title="JSON Representation (application/senml+json)">
<t>Root variables:</t>
<texttable>
<ttcol align="right">SenML</ttcol>
<ttcol align="left">JSON</ttcol>
<ttcol align="left">Type</ttcol>
<c>Base Name</c>
<c>bn</c>
<c>String</c>
<c>Base Time</c>
<c>bt</c>
<c>Number</c>
<c>Base Units</c>
<c>bu</c>
<c>Number</c>
<c>Version</c>
<c>ver</c>
<c>Number</c>
<c>Measurement or Parameters</c>
<c>e</c>
<c>Array</c>
</texttable>
<t>Measurement or Parameter Entries:</t>
<texttable>
<ttcol align="right">SenML</ttcol>
<ttcol align="left">JSON</ttcol>
<ttcol align="left">Notes</ttcol>
<c>Name</c>
<c>n</c>
<c>String</c>
<c>Units</c>
<c>u</c>
<c>String</c>
<c>Value</c>
<c>v</c>
<c>Floating point</c>
<c>String Value</c>
<c>sv</c>
<c>String</c>
<c>Boolean Value</c>
<c>bv</c>
<c>Boolean</c>
<c>Value Sum</c>
<c>s</c>
<c>Floating point</c>
<c>Time</c>
<c>t</c>
<c>Number</c>
<c>Update Time</c>
<c>ut</c>
<c>Number</c>
</texttable>
<t>All of the data is UTF-8, but since this is for machine to machine
communications on constrained systems, only characters with code points
between U+0001 and U+007F are allowed which corresponds to the
ASCII<xref target="RFC0020"></xref> subset of UTF-8.</t>
<t>The root contents MUST consist of exactly one JSON object as
specified by <xref target="RFC4627"></xref>. This object MAY contain a
"bn" attribute with a value of type string. This object MAY contain a
"bt" attribute with a value of type number. The object MAY contain a
"bu" attribute with a value of type string. The object MAY contain a
"ver" attribute with a value of type number. The object MAY contain
other attribute value pairs, and the object MUST contain exactly one "e"
attribute with a value of type array. The array MUST have one or more
measurement or parameter objects.</t>
<t>Inside each measurement or parameter object the "n", "u", and "sv"
attributes are of type string, the "t" and "ut" attributes are of type
number, the "bv" attribute is of type boolean, and the "v" and "s"
attributes are of type floating point. All the attributes are optional,
but as specified in <xref target="semant"></xref>, one of the "v", "sv",
or "bv" attributes MUST appear unless the "s" attribute is also present.
The "v", and "sv", and "bv" attributes MUST NOT appear together.</t>
<t>Systems receiving measurements MUST be able to process the range of
floating point numbers that are representable as an IEEE
double-precision floating-point numbers <xref
target="IEEE.754.1985"></xref>. The number of 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 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 5 characters long. This allows time
values to have better than micro second precision over the next 100
years.</t>
<section title="Examples">
<section title="Single Datapoint">
<t>The following shows a temperature reading taken approximately
"now" by a 1-wire sensor device that was assigned the unique 1-wire
address of 10e2073a01080063:</t>
<figure>
<artwork><![CDATA[
{"e":[{ "n": "urn:dev:ow:10e2073a01080063", "v":23.5 }]}]]></artwork>
</figure>
</section>
<section anchor="co-ex" title="Multiple Datapoints">
<t>The following example shows voltage and current now, i.e., at an
unspecified time. The device has an EUI-64 MAC address of
0024befffe804ff1.</t>
<figure>
<artwork><![CDATA[
{"e":[
{ "n": "voltage", "t": 0, "u": "V", "v": 120.1 },
{ "n": "current", "t": 0, "u": "A", "v": 1.2 }],
"bn": "urn:dev:mac:0024befffe804ff1/"
}]]></artwork>
</figure>
<t>The next example is similar to the above one, but shows current
at Tue Jun 8 18:01:16 UTC 2010 and at each second for the previous 5
seconds.</t>
<!-- times generated with date '+%s' ; date -u ; date '+%s'-->
<figure>
<artwork><![CDATA[
{"e":[
{ "n": "voltage", "u": "V", "v": 120.1 },
{ "n": "current", "t": -5, "v": 1.2 },
{ "n": "current", "t": -4, "v": 1.30 },
{ "n": "current", "t": -3, "v": 0.14e1 },
{ "n": "current", "t": -2, "v": 1.5 },
{ "n": "current", "t": -1, "v": 1.6 },
{ "n": "current", "t": 0, "v": 1.7 }],
"bn": "urn:dev:mac:0024befffe804ff1/",
"bt": 1276020076,
"ver": 1,
"bu": "A"
}]]></artwork>
</figure>
</section>
<section anchor="an-co-ex" title="Multiple Measurements">
<t>The following example shows humidity measurements from a mobile
device with an IPv6 address 2001:db8::1, starting at Mon Oct 31
13:24:24 UTC 2011. The device also provide position data, which is
provided in the same measurement or parameter array as separate
entries. Note time is used to for correlating data that belongs
together, e.g., a measurement and a parameter associated with it.
Finally, the device also reports extra data about its battery status
at a separate time.</t>
<!-- times generated with date '+%s' ; date -u ; date '+%s'-->
<figure>
<artwork><![CDATA[
{"e":[
{ "v": 20.0, "t": 0 },
{ "sv": "E 24' 30.621", "u": "lon", "t": 0 },
{ "sv": "N 60' 7.965", "u": "lat", "t": 0 },
{ "v": 20.3, "t": 60 },
{ "sv": "E 24' 30.622", "u": "lon", "t": 60 },
{ "sv": "N 60' 7.965", "u": "lat", "t": 60 },
{ "v": 20.7, "t": 120 },
{ "sv": "E 24' 30.623", "u": "lon", "t": 120 },
{ "sv": "N 60' 7.966", "u": "lat", "t": 120 },
{ "v": 98.0, "u": "%EL", "t": 150 },
{ "v": 21.2, "t": 180 },
{ "sv": "E 24' 30.628", "u": "lon", "t": 180 },
{ "sv": "N 60' 7.967", "u": "lat", "t": 180 }],
"bn": "http://[2001:db8::1]",
"bt": 1320067464,
"bu": "%RH"
}]]></artwork>
</figure>
</section>
<section anchor="rest-ex" title="Collection of Resources">
<t>The following example shows how to query one device that can
provide multiple measurements. The 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 Mon Oct 31 16:27:09 UTC 2011,
and has gotten two separate values as a result, a temperature and
humidity measurement.</t>
<figure>
<artwork><![CDATA[
{"e":[
{ "n": "temperature", "v": 27.2, "u": "degC" },
{ "n": "humidity", "v": 80, "u": "%RH" }],
"bn": "http://[2001:db8::2]/",
"bt": 1320078429,
"ver": 1
}]]></artwork>
</figure>
</section>
</section>
</section>
<section anchor="sec-xml-examle"
title="XML Representation (application/senml+xml)">
<t>A SenML object can also be represented in XML format as defined in
this section. The following example shows an XML example for the same
sensor measurement as in <xref target="co-ex"></xref>.</t>
<figure>
<artwork><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<senml xmlns="urn:ietf:params:xml:ns:senml"
bn="urn:dev:mac:0024befffe804ff1/"
bt="1276020076"
ver="1" bu="A">
<e n="voltage" u="V" v="120.1" />
<e n="current" t="-5" v="1.2" />
<e n="current" t="-4" v="1.30" />
<e n="current" t="-3" v="0.14e1" />
<e n="current" t="-2" v="1.5" />
<e n="current" t="-1" v="1.6" />
<e n="current" t="0" v="1.7" />
</senml>
]]></artwork>
</figure>
<t>The RelaxNG schema for the XML is:</t>
<figure>
<artwork><![CDATA[
default namespace = "urn:ietf:params:xml:ns:senml"
namespace rng = "http://relaxng.org/ns/structure/1.0"
e = element e {
attribute n { xsd:string }?,
attribute u { xsd:string }?,
attribute v { xsd:float }?,
attribute sv { xsd:string }?,
attribute bv { xsd:boolean }?,
attribute s { xsd:decimal }?,
attribute t { xsd:integer }?,
attribute ut { xsd:integer }?,
p*
}
senml =
element senml {
attribute bn { xsd:string }?,
attribute bt { xsd:integer }?,
attribute bu { xsd:string }?,
attribute ver { xsd:integer }?,
e*
}
start = senml
]]></artwork>
</figure>
</section>
<section title="EXI Representation (application/senml+exi)">
<t>For efficient transmission of SenML over e.g. a constrained network,
Efficient XML Interchange (EXI) can be used. This encodes the XML Schema
structure of SenML into binary tags and values rather than ASCII text.
An EXI representation of SenML SHOULD be made using the strict
schema-mode of EXI. This mode however does not allow tag extensions to
the schema, and therefore any extensions will be lost in the encoding.
For uses where extensions need to be preserved in EXI, the non-strict
schema mode of EXI MAY be used.</t>
<t>The EXI header option MUST be included. An EXI schemaID options MUST
be set to value of "a" indicating the scheme provided in this
specification. Future revisions to the schema can change this schemaID
to allow for backwards compatibility. When the data will be transported
over COAP or HTTP, an EXI Cookie SHOULD NOT be used as it simply makes
things larger as is redundant to information provided in the
Content-Type header.</t>
<t>The following XSD Schema is generated from the RelaxNG and used for
strict schema guided EXI processing.</t>
<figure>
<artwork><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
elementFormDefault="qualified"
targetNamespace="urn:ietf:params:xml:ns:senml"
xmlns:ns1="urn:ietf:params:xml:ns:senml">
<xs:element name="e">
<xs:complexType>
<xs:attribute name="n" type="xs:string"/>
<xs:attribute name="u" type="xs:string"/>
<xs:attribute name="v" type="xs:float"/>
<xs:attribute name="sv" type="xs:string"/>
<xs:attribute name="bv" type="xs:boolean"/>
<xs:attribute name="s" type="xs:decimal"/>
<xs:attribute name="t" type="xs:integer"/>
<xs:attribute name="ut" type="xs:integer"/>
</xs:complexType>
</xs:element>
<xs:element name="senml">
<xs:complexType>
<xs:sequence>
<xs:element minOccurs="0" maxOccurs="unbounded" ref="ns1:e"/>
</xs:sequence>
<xs:attribute name="bn" type="xs:string"/>
<xs:attribute name="bt" type="xs:integer"/>
<xs:attribute name="bu" type="xs:string"/>
<xs:attribute name="ver" type="xs:integer"/>
</xs:complexType>
</xs:element>
</xs:schema>
]]></artwork>
</figure>
<t>The following shows a hexdump of the EXI produced from encoding the
following XML example. Note that while this example is similar to the
first example in <xref target="co-ex"></xref> in JSON format.</t>
<figure>
<artwork><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<senml xmlns="urn:ietf:params:xml:ns:senml"
bn="urn:dev:ow:10e2073a01080063" >
<e n="voltage" t="0" v="120.1" u="V" />
<e n="current" t="0" v="1.2" u="A" />
</senml>
]]></artwork>
</figure>
<t>Which compresses to the following displayed in hexdump:</t>
<figure>
<artwork><![CDATA[
00000000 a0 30 0d 85 01 d7 57 26 e3 a6 46 57 63 a6 f7 73
00000010 a3 13 06 53 23 03 73 36 13 03 13 03 83 03 03 63
00000020 36 21 2e cd ed 8e 8c 2c ec a8 00 00 d5 95 88 4c
00000030 02 08 4b 1b ab 93 93 2b 73 a2 00 00 34 14 19 00
00000040 c0
]]></artwork>
</figure>
<t>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 for
a simple sensor to produce valid EXI without really implementing 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 would
produce XML SenML file such as:</t>
<figure>
<artwork><![CDATA[
<?xml version="1.0" encoding="UTF-8"?>
<senml xmlns="urn:ietf:params:xml:ns:senml"
bn="urn:dev:ow:10e2073a01080063" >
<e n="temp" v="23.1" u="degC" />
</senml>
]]></artwork>
</figure>
<t>The compressed form, using the byte alignment option of EXI, for the
above XML is the following:</t>
<figure>
<artwork><![CDATA[
00000000 a00048806c200200 1d75726e3a646576 |..H.l ...urn:dev|
00000010 3a6f773a31306532 3037336130313038 |:ow:10e2073a0108|
00000020 3030363303010674 656d700306646567 |0063...temp..deg|
00000030 430100e701010001 02 |C........|
]]></artwork>
</figure>
<t>A small temperature sensor devices that only generates this one EXI
file does not really need an full EXI implementation. It can simple hard
code the output replacing the one wire device ID starting at byte 0x14
and going to byte 0x23 with it's device ID , and replacing the value
"0xe7 0x01" at location 0x33 to 0x34 with the current temperature. The
EXI Specification<xref target="W3C.REC-exi-20110310"></xref> contains
the full information on how floating point numbers are represented, 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 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 location 0x33 is set to low 7 bits
of the integer temperature in tenths of degrees plus 0x80. In this
example 231 & 0x7F + 0x80 = 0xE7. The second byte at location 0x34
is set to the integer temperature in tenths of degrees right shifted 7
bits. In this example 231 >> 7 = 0x01.</t>
</section>
<section title="Usage Considerations">
<t>The measurements support sending both the current value of a sensor
as well as the an integrated sum. For many types of measurements, the
sum is more useful than the current value. For example, an electrical
meter that measures the energy a given computer uses will typically want
to measure the cumulative amount of energy used. This is less prone to
error than reporting the power each second and trying to have something
on the server side sum together all the power measurements. 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 reflect what
happened while the network was 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 "s" attribute of the measurement. It might
optionally include the current power in the "v" attribute.</t>
<t>While the benefit of using the integrated sum is fairly clear for
measurements like power and energy, it is less obvious for something
like temperature. Reporting the sum of the temperature makes it easy to
compute averages even when the individual temperature values are not
reported frequently enough to compute accurate averages. Implementors
are encouraged to report the cumulative sum as well as the raw value of
a given sensor.</t>
<t>Applications that use the cumulative sum values need to understand
they are very loosely defined by this specification, and depending on
the particular sensor implementation may behave in unexpected ways.
Applications should be able to deal with the following issues:</t>
<t><list style="numbers">
<t>Many sensors will allow the cumulative sums to "wrap" back to
zero after the value gets sufficiently large.</t>
<t>Some sensors will reset the cumulative sum back to zero when the
device is reset, loses power, or is replaced with a different
sensor.</t>
<t>Applications cannot make assumptions about when the device
started accumulating values into the sum.</t>
</list></t>
<t>Typically applications can make some assumptions about specific
sensors that will allow them to deal with these problems. A common
assumption is that for sensors whose measurement values are always
positive, the sum should never get smaller; so if the sum does get
smaller, the application will know that one of the situations listed
above has happened.</t>
</section>
<section title="IANA Considerations">
<t>Note to RFC Editor: Please replace all occurrences of "RFC-AAAA" with
the RFC number of this specification.</t>
<section anchor="sec-units" title="Units Registry">
<t>IANA will create a registry of unit symbols. The primary purpose of
this registry is to make sure that symbols uniquely map to give type
of measurement. Definitions for many of these units can be found in
<xref target="NIST822"></xref> and <xref target="BIPM"></xref>.</t>
<texttable>
<ttcol align="right">Symbol</ttcol>
<ttcol align="left">Description</ttcol>
<ttcol align="left">Reference</ttcol>
<c>m</c>
<c>meter</c>
<c>RFC-AAAA</c>
<c>kg</c>
<c>kilogram</c>
<c>RFC-AAAA</c>
<c>s</c>
<c>second</c>
<c>RFC-AAAA</c>
<c>A</c>
<c>ampere</c>
<c>RFC-AAAA</c>
<c>K</c>
<c>kelvin</c>
<c>RFC-AAAA</c>
<c>cd</c>
<c>candela</c>
<c>RFC-AAAA</c>
<c>mol</c>
<c>mole</c>
<c>RFC-AAAA</c>
<c>Hz</c>
<c>hertz</c>
<c>RFC-AAAA</c>
<c>rad</c>
<c>radian</c>
<c>RFC-AAAA</c>
<c>sr</c>
<c>steradian</c>
<c>RFC-AAAA</c>
<c>N</c>
<c>newton</c>
<c>RFC-AAAA</c>
<c>Pa</c>
<c>pascal</c>
<c>RFC-AAAA</c>
<c>J</c>
<c>joule</c>
<c>RFC-AAAA</c>
<c>W</c>
<c>watt</c>
<c>RFC-AAAA</c>
<c>C</c>
<c>coulomb</c>
<c>RFC-AAAA</c>
<c>V</c>
<c>volt</c>
<c>RFC-AAAA</c>
<c>F</c>
<c>farad</c>
<c>RFC-AAAA</c>
<c>Ohm</c>
<c>ohm</c>
<c>RFC-AAAA</c>
<c>S</c>
<c>siemens</c>
<c>RFC-AAAA</c>
<c>Wb</c>
<c>weber</c>
<c>RFC-AAAA</c>
<c>T</c>
<c>tesla</c>
<c>RFC-AAAA</c>
<c>H</c>
<c>henry</c>
<c>RFC-AAAA</c>
<c>degC</c>
<c>degrees Celsius</c>
<c>RFC-AAAA</c>
<c>lm</c>
<c>lumen</c>
<c>RFC-AAAA</c>
<c>lx</c>
<c>lux</c>
<c>RFC-AAAA</c>
<c>Bq</c>
<c>becquerel</c>
<c>RFC-AAAA</c>
<c>Gy</c>
<c>gray</c>
<c>RFC-AAAA</c>
<c>Sv</c>
<c>sievert</c>
<c>RFC-AAAA</c>
<c>kat</c>
<c>katal</c>
<c>RFC-AAAA</c>
<c>pH</c>
<c>pH acidity</c>
<c>RFC-AAAA</c>
<c>%</c>
<c>Value of a switch. A value of 0.0 indicates the switch is off
while 100.0 indicates on.</c>
<c>RFC-AAAA</c>
<c>count</c>
<c>counter value</c>
<c>RFC-AAAA</c>
<c>%RH</c>
<c>Relative Humidity</c>
<c>RFC-AAAA</c>
<c>m2</c>
<c>area</c>
<c>RFC-AAAA</c>
<c>l</c>
<c>volume in liters</c>
<c>RFC-AAAA</c>
<!-- should this be m3 -->
<c>m/s</c>
<c>velocity</c>
<c>RFC-AAAA</c>
<c>m/s2</c>
<c>acceleration</c>
<c>RFC-AAAA</c>
<c>l/s</c>
<c>flow rate in liters per second</c>
<c>RFC-AAAA</c>
<!-- should this be m3/s -->
<c>W/m2</c>
<c>irradiance</c>
<c>RFC-AAAA</c>
<c>cd/m2</c>
<c>luminance</c>
<c>RFC-AAAA</c>
<c>Bspl</c>
<c>bel sound pressure level</c>
<c>RFC-AAAA</c>
<c>bit/s</c>
<c>bits per second</c>
<c>RFC-AAAA</c>
<c>lat</c>
<c>degrees latitude. Assumed to be in WGS84 unless another reference
frame is known for the sensor.</c>
<c>RFC-AAAA</c>
<c>lon</c>
<c>degrees longitude. Assumed to be in WGS84 unless another
reference frame is known for the sensor.</c>
<c>RFC-AAAA</c>
<c>%EL</c>
<c>remaining battery energy level in percents</c>
<c>RFC-AAAA</c>
<c>EL</c>
<c>remaining battery energy level in seconds</c>
<c>RFC-AAAA</c>
<c>beet/m</c>
<c>Heart rate in beets per minute</c>
<c>RFC-AAAA</c>
<c>beets</c>
<c>Cumulative number of heart beats</c>
<c>RFC-AAAA</c>
</texttable>
<t>New entries can be added to the registration by either Expert
Review or IESG Approval as defined in <xref target="RFC5226"></xref>.
Experts should exercise their own good judgment but need to consider
the following guidelines:</t>
<t><list style="numbers">
<t>There needs to be a real and compelling use for any new unit to
be added.</t>
<t>Units should define the semantic information and be chosen
carefully. Implementors need to remember that the same word may be
used in different real-life contexts. For example, degrees when
measuring latitude have no semantic relation to degrees when
measuring temperature; thus two different units are needed.</t>
<t>These measurements are produced by computers for consumption by
computers. The principle is that conversion has to be easily be
done when both reading and writing the media type. The value of a
single canonical representation outweighs the convenience of easy
human representations or loss of precision in a conversion.</t>
<t>Use of SI prefixes such as "k" before the unit is not allowed.
Instead one can represent the value using scientific notation such
a 1.2e3.</t>
<t>For a given type of measurement, there will only be one unit
type defined. So for length, meters are defined and other lengths
such as mile, foot, light year are not allowed. For most cases,
the SI unit is preferred.</t>
<t>Symbol names that could be easily confused with existing common
units or units combined with prefixes should be avoided. For
example, selecting a unit name of "mph" to indicate something that
had nothing to do with velocity would be a bad choice, as "mph" is
commonly used to mean miles per hour.</t>
<t>The following should not be used because the are common SI
prefixes: Y, Z, E, P, T, G, M, k, h, da, d, c, n, u, p, f, a, z,
y, Ki, Mi, Gi, Ti, Pi, Ei, Zi, Yi.</t>
<t>The following units should not be used as they are commonly
used to represent other measurements Ky, Gal, dyn, etg, P, St, Mx,
G, Oe, Gb, sb, Lmb, ph, Ci, R, RAD, REM, gal, bbl, qt, degF, Cal,
BTU, HP, pH, B/s, psi, Torr, atm, at, bar, kWh.</t>
<t>The unit names are case sensitive and the correct case needs to
be used, but symbols that differ only in case should not be
allocated.</t>
<t>A number after a unit typically indicates the previous unit
raised to that power, and the / indicates that the units that
follow are the reciprocal. A unit should have only one / in the
name.</t>
</list></t>
</section>
<section anchor="sec-iana-media" title="Media Type Registration">
<t>The following registrations are done following the procedure
specified in <xref target="RFC4288"></xref> and <xref
target="RFC3023"></xref>.</t>
<t>Note to RFC Editor: Please replace all occurrences of "RFC-AAAA"
with the RFC number of this specification.</t>
<section title="senml+json Media Type Registration">
<t>Type name: application</t>
<t>Subtype name: senml+json</t>
<t>Required parameters: none</t>
<t>Optional parameters: none</t>
<t>Encoding considerations: Must be encoded as using a subset of the
encoding allowed in <xref target="RFC4627"></xref>. Specifically,
only the ASCII<xref target="RFC0020"></xref> subset of the UTF-8
characters are allowed. This simplifies implementation of very
simple system and does not impose any significant limitations as all
this data is meant for machine to machine communications and is not
meant to be human readable.</t>
<t>Security considerations: Sensor data can contain a wide range of
information ranging from information that is very public, such the
outside temperature in a given city, to very private information
that requires integrity and confidentiality protection, such as
patient health information. This format does not provide any
security and instead relies on the transport protocol that carries
it to provide security. Given applications need to look at the
overall context of how this media type will be used to decide if the
security is adequate.</t>
<t>Interoperability considerations: Applications should ignore any
JSON key value pairs that they do not understand. This allows
backwards compatibility extensions to this specification. The "ver"
field can be used to ensure the receiver supports a minimal level of
functionality needed by the creator of the JSON object.</t>
<t>Published specification: RFC-AAAA</t>
<t>Applications that use this media type: The type is used by
systems that report electrical power usage and environmental
information such as temperature and humidity. It can be used for a
wide range of sensor reporting systems.</t>
<t>Additional information:</t>
<t>Magic number(s): none</t>
<t>File extension(s): senml</t>
<t>Macintosh file type code(s): none</t>
<t>Person & email address to contact for further information:
Cullen Jennings <c.jennings@ieee.org></t>
<t>Intended usage: COMMON</t>
<t>Restrictions on usage: None</t>
<t>Author: Cullen Jennings <c.jennings@ieee.org></t>
<t>Change controller: IESG</t>
</section>
<section title="senml+xml Media Type Registration">
<t>Type name: application</t>
<t>Subtype name: senml+xml</t>
<t>Required parameters: none</t>
<t>Optional parameters: none</t>
<t>Encoding considerations: TBD</t>
<t>Security considerations: TBD</t>
<t>Interoperability considerations: TBD</t>
<t>Published specification: RFC-AAAA</t>
<t>Applications that use this media type: TBD</t>
<t>Additional information:</t>
<t>Magic number(s): none</t>
<t>File extension(s): senml</t>
<t>Macintosh file type code(s): none</t>
<t>Person & email address to contact for further information:
Cullen Jennings <c.jennings@ieee.org></t>
<t>Intended usage: COMMON</t>
<t>Restrictions on usage: None</t>
<t>Author: Cullen Jennings <c.jennings@ieee.org></t>
<t>Change controller: IESG</t>
</section>
<section title="senml+exi Media Type Registration">
<t>Type name: application</t>
<t>Subtype name: senml+exi</t>
<t>Required parameters: none</t>
<t>Optional parameters: none</t>
<t>Encoding considerations: TBD</t>
<t>Security considerations: TBD</t>
<t>Interoperability considerations: TBD</t>
<t>Published specification: RFC-AAAA</t>
<t>Applications that use this media type: TBD</t>
<t>Additional information:</t>
<t>Magic number(s): none</t>
<t>File extension(s): senml</t>
<t>Macintosh file type code(s): none</t>
<t>Person & email address to contact for further information:
Cullen Jennings <c.jennings@ieee.org></t>
<t>Intended usage: COMMON</t>
<t>Restrictions on usage: None</t>
<t>Author: Cullen Jennings <c.jennings@ieee.org></t>
<t>Change controller: IESG</t>
</section>
</section>
<section anchor="sec-iana-url" title="XML Namespace Registration">
<t>This document registers the following XML name paces in the IETF
XML registry defined in <xref target="RFC3688"></xref>.</t>
<t>URI: urn:ietf:params:xml:ns:senml</t>
<t>Registrant Contact: The IESG.</t>
<t>XML: N/A, the requested URIs are XML namespaces</t>
</section>
</section>
<section anchor="sec-sec" title="Security Considerations">
<t>See <xref target="sec-privacy"></xref>.Further discussion of security
proprieties can be found in <xref target="sec-iana-media"></xref>.</t>
</section>
<section anchor="sec-privacy" title="Privacy Considerations">
<t>Sensor data can range from information with almost no security
considerations, such as the current temperature in a given city, to
highly sensitive medical or location data. This specification provides
no security protection for the data but is meant to be used inside
another container or transport protocol such as S/MIME or HTTP with TLS
that can provide integrity, confidentiality, and authentication
information about the source of the data. </t>
</section>
<section title="Acknowledgement">
<t>We would like to thank Lisa Dusseault, Joe Hildebrand, Lyndsay
Campbell, Martin Thomson, John Klensin, Bjoern Hoehrmann, and Carsten
Bormann for their review comments.</t>
</section>
</middle>
<back>
<references title="Normative References">
<reference anchor="RFC3688">
<front>
<title>The IETF XML Registry</title>
<author fullname="M. Mealling" initials="M." surname="Mealling">
<organization></organization>
</author>
<date month="January" year="2004" />
<abstract>
<t>This document describes an IANA maintained registry for IETF
standards which use Extensible Markup Language (XML) related items
such as Namespaces, Document Type Declarations (DTDs), Schemas,
and Resource Description Framework (RDF) Schemas.</t>
</abstract>
</front>
<seriesInfo name="BCP" value="81" />
<seriesInfo name="RFC" value="3688" />
<format octets="17325"
target="http://www.rfc-editor.org/rfc/rfc3688.txt" type="TXT" />
</reference>
<reference anchor="W3C.REC-exi-20110310"
target="http://www.w3.org/TR/2011/REC-exi-20110310">
<front>
<title>Efficient XML Interchange (EXI) Format 1.0</title>
<author fullname="Takuki Kamiya" initials="T." surname="Kamiya">
<organization></organization>
</author>
<author fullname="John Schneider" initials="J." surname="Schneider">
<organization></organization>
</author>
<date day="10" month="March" year="2011" />
</front>
<seriesInfo name="World Wide Web Consortium Recommendation"
value="REC-exi-20110310" />
<format target="http://www.w3.org/TR/2011/REC-exi-20110310"
type="HTML" />
</reference>
<reference anchor="RFC4627">
<front>
<title>The application/json Media Type for JavaScript Object
Notation (JSON)</title>
<author fullname="D. Crockford" initials="D." surname="Crockford">
<organization></organization>
</author>
<date month="July" year="2006" />
<abstract>
<t>JavaScript Object Notation (JSON) is a lightweight, text-based,
language-independent data interchange format. It was derived from
the ECMAScript Programming Language Standard. JSON defines a small
set of formatting rules for the portable representation of
structured data. This memo provides information for the Internet
community.</t>
</abstract>
</front>
<seriesInfo name="RFC" value="4627" />
<format octets="16319"
target="http://www.rfc-editor.org/rfc/rfc4627.txt" type="TXT" />
</reference>
<reference anchor="RFC3023">
<front>
<title>XML Media Types</title>
<author fullname="M. Murata" initials="M." surname="Murata">
<organization></organization>
</author>
<author fullname="S. St. Laurent" initials="S."
surname="St. Laurent">
<organization></organization>
</author>
<author fullname="D. Kohn" initials="D." surname="Kohn">
<organization></organization>
</author>
<date month="January" year="2001" />
<abstract>
<t>This document standardizes five new media types -- text/xml,
application/xml, text/xml-external-parsed-entity, application/xml-
external-parsed-entity, and application/xml-dtd -- for use in
exchanging network entities that are related to the Extensible
Markup Language (XML). This document also standardizes a
convention (using the suffix '+xml') for naming media types
outside of these five types when those media types represent XML
MIME (Multipurpose Internet Mail Extensions) entities. [STANDARDS
TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="3023" />
<format octets="86011"
target="http://www.rfc-editor.org/rfc/rfc3023.txt" type="TXT" />
</reference>
<reference anchor="RFC4288">
<front>
<title>Media Type Specifications and Registration Procedures</title>
<author fullname="N. Freed" initials="N." surname="Freed">
<organization></organization>
</author>
<author fullname="J. Klensin" initials="J." surname="Klensin">
<organization></organization>
</author>
<date month="December" year="2005" />
<abstract>
<t>This document defines procedures for the specification and
registration of media types for use in MIME and other Internet
protocols. This document specifies an Internet Best Current
Practices for the Internet Community, and requests discussion and
suggestions for improvements.</t>
</abstract>
</front>
<seriesInfo name="BCP" value="13" />
<seriesInfo name="RFC" value="4288" />
<format octets="52667"
target="http://www.rfc-editor.org/rfc/rfc4288.txt" type="TXT" />
</reference>
<reference anchor="RFC2119">
<front>
<title abbrev="RFC Key Words">Key words for use in RFCs to Indicate
Requirement Levels</title>
<author fullname="Scott Bradner" initials="S." surname="Bradner">
<organization>Harvard University</organization>
<address>
<postal>
<street>1350 Mass. Ave.</street>
<street>Cambridge</street>
<street>MA 02138</street>
</postal>
<phone>- +1 617 495 3864</phone>
<email>sob@harvard.edu</email>
</address>
</author>
<date month="March" year="1997" />
<area>General</area>
<keyword>keyword</keyword>
<abstract>
<t>In many standards track documents several words are used to
signify the requirements in the specification. These words are
often capitalized. This document defines these words as they
should be interpreted in IETF documents. Authors who follow these
guidelines should incorporate this phrase near the beginning of
their document: <list style="empty">
<t>The key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
"SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described
in RFC 2119.</t>
</list></t>
<t>Note that the force of these words is modified by the
requirement level of the document in which they are used.</t>
</abstract>
</front>
<seriesInfo name="BCP" value="14" />
<seriesInfo name="RFC" value="2119" />
<format octets="4723"
target="http://www.rfc-editor.org/rfc/rfc2119.txt" type="TXT" />
<format octets="17491"
target="http://xml.resource.org/public/rfc/html/rfc2119.html"
type="HTML" />
<format octets="5777"
target="http://xml.resource.org/public/rfc/xml/rfc2119.xml"
type="XML" />
</reference>
<reference anchor="IEEE.754.1985">
<front>
<title>Standard for Binary Floating-Point Arithmetic</title>
<author>
<organization>Institute of Electrical and Electronics
Engineers</organization>
</author>
<date month="August" year="1985" />
</front>
<seriesInfo name="IEEE" value="Standard 754" />
</reference>
<reference anchor="RFC5226">
<front>
<title>Guidelines for Writing an IANA Considerations Section in
RFCs</title>
<author fullname="T. Narten" initials="T." surname="Narten">
<organization></organization>
</author>
<author fullname="H. Alvestrand" initials="H." surname="Alvestrand">
<organization></organization>
</author>
<date month="May" year="2008" />
</front>
<seriesInfo name="BCP" value="26" />
</reference>
</references>
<references title="Informative References">
<reference anchor="RFC2141">
<front>
<title>URN Syntax</title>
<author fullname="Ryan Moats" initials="R." surname="Moats">
<organization>AT&T</organization>
<address>
<postal>
<street>15621 Drexel Circle</street>
<street>Omaha</street>
<street>NE 68135-2358</street>
<country>USA</country>
</postal>
<phone>+1 402 894-9456</phone>
<email>jayhawk@ds.internic.net</email>
</address>
</author>
<date month="May" year="1997" />
<area>Applications</area>
<keyword>URN</keyword>
<keyword>uniform resource</keyword>
</front>
<seriesInfo name="RFC" value="2141" />
<format octets="14077" target="ftp://ftp.isi.edu/in-notes/rfc2141.txt"
type="TXT" />
<format octets="17687"
target="http://xml.resource.org/public/rfc/xml/rfc2141.xml"
type="XML" />
</reference>
<reference anchor="RFC3986">
<front>
<title abbrev="URI Generic Syntax">Uniform Resource Identifier
(URI): Generic Syntax</title>
<author fullname="Tim Berners-Lee" initials="T."
surname="Berners-Lee">
<organization abbrev="W3C/MIT">World Wide Web
Consortium</organization>
<address>
<postal>
<street>Massachusetts Institute of Technology</street>
<street>77 Massachusetts Avenue</street>
<city>Cambridge</city>
<region>MA</region>
<code>02139</code>
<country>USA</country>
</postal>
<phone>+1-617-253-5702</phone>
<facsimile>+1-617-258-5999</facsimile>
<email>timbl@w3.org</email>
<uri>http://www.w3.org/People/Berners-Lee/</uri>
</address>
</author>
<author fullname="Roy T. Fielding" initials="R." surname="Fielding">
<organization abbrev="Day Software">Day Software</organization>
<address>
<postal>
<street>5251 California Ave., Suite 110</street>
<city>Irvine</city>
<region>CA</region>
<code>92617</code>
<country>USA</country>
</postal>
<phone>+1-949-679-2960</phone>
<facsimile>+1-949-679-2972</facsimile>
<email>fielding@gbiv.com</email>
<uri>http://roy.gbiv.com/</uri>
</address>
</author>
<author fullname="Larry Masinter" initials="L." surname="Masinter">
<organization abbrev="Adobe Systems">Adobe Systems
Incorporated</organization>
<address>
<postal>
<street>345 Park Ave</street>
<city>San Jose</city>
<region>CA</region>
<code>95110</code>
<country>USA</country>
</postal>
<phone>+1-408-536-3024</phone>
<email>LMM@acm.org</email>
<uri>http://larry.masinter.net/</uri>
</address>
</author>
<date month="January" year="2005" />
<area>Applications</area>
<keyword>uniform resource identifier</keyword>
<keyword>URI</keyword>
<keyword>URL</keyword>
<keyword>URN</keyword>
<keyword>WWW</keyword>
<keyword>resource</keyword>
</front>
<seriesInfo name="STD" value="66" />
<seriesInfo name="RFC" value="3986" />
<format octets="141811"
target="ftp://ftp.isi.edu/in-notes/rfc3986.txt" type="TXT" />
<format octets="213584"
target="http://xml.resource.org/public/rfc/html/rfc3986.html"
type="HTML" />
<format octets="163534"
target="http://xml.resource.org/public/rfc/xml/rfc3986.xml"
type="XML" />
</reference>
<reference anchor="I-D.ietf-core-coap">
<front>
<title>Constrained Application Protocol (CoAP)</title>
<author fullname="Zach Shelby" initials="Z" surname="Shelby">
<organization></organization>
</author>
<author fullname="Klaus Hartke" initials="K" surname="Hartke">
<organization></organization>
</author>
<author fullname="Carsten Bormann" initials="C" surname="Bormann">
<organization></organization>
</author>
<author fullname="Brian Frank" initials="B" surname="Frank">
<organization></organization>
</author>
<date day="31" month="October" year="2011" />
<abstract>
<t>This document specifies the Constrained Application Protocol
(CoAP), a specialized web transfer protocol for use with
constrained networks and nodes for machine-to-machine applications
such as smart energy and building automation. These constrained
nodes often have 8-bit microcontrollers with small amounts of ROM
and RAM, while networks such as 6LoWPAN often have high packet
error rates and a typical throughput of 10s of kbit/s. CoAP
provides a method/response interaction model between application
end-points, supports built-in resource discovery, and includes key
web concepts such as URIs and content-types. CoAP easily
translates to HTTP for integration with the web while meeting
specialized requirements such as multicast support, very low
overhead and simplicity for constrained environments.</t>
</abstract>
</front>
<seriesInfo name="Internet-Draft" value="draft-ietf-core-coap-08" />
<format target="http://www.ietf.org/internet-drafts/draft-ietf-core-coap-08.txt"
type="TXT" />
</reference>
<reference anchor="I-D.ietf-core-link-format">
<front>
<title>CoRE Link Format</title>
<author fullname="Zach Shelby" initials="Z" surname="Shelby">
<organization></organization>
</author>
<date day="16" month="November" year="2011" />
<abstract>
<t>This document defines Web Linking using a link format for use
by constrained web servers to describe hosted resources, their
attributes and other relationships between links. Based on the
HTTP Link Header format defined in RFC5988, the CoRE Link Format
is carried as a payload and is assigned an Internet media type. A
well- known URI is defined as a default entry-point for requesting
the links hosted by a server.</t>
</abstract>
</front>
<seriesInfo name="Internet-Draft"
value="draft-ietf-core-link-format-09" />
<format target="http://www.ietf.org/internet-drafts/draft-ietf-core-link-format-09.txt"
type="TXT" />
</reference>
<reference anchor="BIPM">
<front>
<title>The International System of Units (SI)</title>
<author>
<organization>Bureau International des Poids et
Mesures</organization>
</author>
</front>
<seriesInfo name="8th edition, 2006" value="" />
<format target="http://www.bipm.org/utils/common/pdf/si_brochure_8_en.pdf"
type="PDF" />
</reference>
<reference anchor="NIST822">
<front>
<title>Guide for the Use of the International System of Units
(SI)</title>
<author initials="A." surname="Thompson">
<organization />
</author>
<author initials="B." surname="Taylor">
<organization />
</author>
</front>
<seriesInfo name="NIST Special Publication 811, 2008 Edition" value="" />
<format target="http://physics.nist.gov/cuu/pdf/sp811.pdf" type="PDF" />
</reference>
<reference anchor="RFC5952">
<front>
<title>A Recommendation for IPv6 Address Text Representation</title>
<author fullname="S. Kawamura" initials="S." surname="Kawamura">
<organization></organization>
</author>
<author fullname="M. Kawashima" initials="M." surname="Kawashima">
<organization></organization>
</author>
<date month="August" year="2010" />
<abstract>
<t>As IPv6 deployment increases, there will be a dramatic increase
in the need to use IPv6 addresses in text. While the IPv6 address
architecture in Section 2.2 of RFC 4291 describes a flexible model
for text representation of an IPv6 address, this flexibility has
been causing problems for operators, system engineers, and users.
This document defines a canonical textual representation format.
It does not define a format for internal storage, such as within
an application or database. It is expected that the canonical
format will be followed by humans and systems when representing
IPv6 addresses as text, but all implementations must accept and be
able to handle any legitimate RFC 4291 format. [STANDARDS
TRACK]</t>
</abstract>
</front>
<seriesInfo name="RFC" value="5952" />
<format octets="26570"
target="http://www.rfc-editor.org/rfc/rfc5952.txt" type="TXT" />
</reference>
<reference anchor="RFC4122">
<front>
<title abbrev="UUID URN">A Universally Unique IDentifier (UUID) URN
Namespace</title>
<author fullname="Paul J. Leach" initials="P." surname="Leach">
<organization>Microsoft</organization>
<address>
<postal>
<street>1 Microsoft Way</street>
<city>Redmond</city>
<region>WA</region>
<code>98052</code>
<country>US</country>
</postal>
<phone>+1 425-882-8080</phone>
<email>paulle@microsoft.com</email>
</address>
</author>
<author fullname="Michael Mealling" initials="M." surname="Mealling">
<organization>Refactored Networks, LLC</organization>
<address>
<postal>
<street>1635 Old Hwy 41</street>
<street>Suite 112, Box 138</street>
<city>Kennesaw</city>
<region>GA</region>
<code>30152</code>
<country>US</country>
</postal>
<phone>+1-678-581-9656</phone>
<email>michael@refactored-networks.com</email>
<uri>http://www.refactored-networks.com</uri>
</address>
</author>
<author fullname="Rich Salz" initials="R." surname="Salz">
<organization>DataPower Technology, Inc.</organization>
<address>
<postal>
<street>1 Alewife Center</street>
<city>Cambridge</city>
<region>MA</region>
<code>02142</code>
<country>US</country>
</postal>
<phone>+1 617-864-0455</phone>
<email>rsalz@datapower.com</email>
<uri>http://www.datapower.com</uri>
</address>
</author>
<date month="July" year="2005" />
<keyword>URN, UUID</keyword>
<abstract>
<t>This specification defines a Uniform Resource Name namespace
for UUIDs (Universally Unique IDentifier), also known as GUIDs
(Globally Unique IDentifier). A UUID is 128 bits long, and can
guarantee uniqueness across space and time. UUIDs were originally
used in the Apollo Network Computing System and later in the Open
Software Foundation's (OSF) Distributed Computing Environment
(DCE), and then in Microsoft Windows platforms.</t>
<t>This specification is derived from the DCE specification with
the kind permission of the OSF (now known as The Open Group).
Information from earlier versions of the DCE specification have
been incorporated into this document.</t>
</abstract>
</front>
<seriesInfo name="RFC" value="4122" />
<format octets="59319"
target="http://www.rfc-editor.org/rfc/rfc4122.txt" type="TXT" />
<format octets="82717"
target="http://xml.resource.org/public/rfc/html/rfc4122.html"
type="HTML" />
<format octets="62931"
target="http://xml.resource.org/public/rfc/xml/rfc4122.xml"
type="XML" />
</reference>
<reference anchor="RFC0020">
<front>
<title>ASCII format for network interchange</title>
<author fullname="Vint Cerf" initials="V." surname="Cerf">
<organization>University California Los Angeles
(UCLA)</organization>
</author>
<date day="16" month="October" year="1969" />
<abstract>
<t>For concreteness, we suggest the use of standard 7-bit ASCII
embedded in an 8 bit byte whose high order bit is always 0.</t>
</abstract>
</front>
<seriesInfo name="RFC" value="20" />
<format octets="18504"
target="http://www.rfc-editor.org/rfc/rfc20.txt" type="TXT" />
</reference>
<reference anchor="I-D.arkko-core-dev-urn">
<front>
<title>Uniform Resource Names for Device Identifiers</title>
<author fullname="Jari Arkko" initials="J" surname="Arkko">
<organization></organization>
</author>
<author fullname="Cullen Jennings" initials="C" surname="Jennings">
<organization></organization>
</author>
<author fullname="Zach Shelby" initials="Z" surname="Shelby">
<organization></organization>
</author>
<date day="31" month="October" year="2011" />
<abstract>
<t>This memo describes a new Uniform Resource Name (URN) namespace
for hardware device identifiers. A general representation of
device identity can be useful in many applications, such as in
sensor data streams and storage, or equipment inventories. A
URN-based representation can be easily passed along in any
application that needs the information.</t>
</abstract>
</front>
<seriesInfo name="Internet-Draft" value="draft-arkko-core-dev-urn-01" />
<format target="http://www.ietf.org/internet-drafts/draft-arkko-core-dev-urn-01.txt"
type="TXT" />
</reference>
<reference anchor="WADL"
target="http://java.net/projects/wadl/sources/svn/content/trunk/www/wadl20090202.pdf">
<front>
<title>Web Application Description Language (WADL)</title>
<author fullname="Marc J. Hadley" initials="M.J.H" surname="Hadley">
<organization>Sun Microsystems Inc.</organization>
</author>
<date year="2009" />
</front>
</reference>
</references>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-22 21:57:27 |