< draft-ietf-core-senml-etch-02.txt   draft-ietf-core-senml-etch-03.txt >
Network Working Group A. Keranen Network Working Group A. Keranen
Internet-Draft Ericsson Internet-Draft Ericsson
Intended status: Standards Track M. Mohajer Intended status: Standards Track M. Mohajer
Expires: August 22, 2019 u-blox UK Expires: September 13, 2019 u-blox UK
February 18, 2019 March 12, 2019
FETCH & PATCH with Sensor Measurement Lists (SenML) FETCH & PATCH with Sensor Measurement Lists (SenML)
draft-ietf-core-senml-etch-02 draft-ietf-core-senml-etch-03
Abstract Abstract
The Sensor Measurement Lists (SenML) media type and data model can be The Sensor Measurement Lists (SenML) media type and data model can be
used to send collections of resources, such as batches of sensor data used to send collections of resources, such as batches of sensor data
or configuration parameters. The CoAP iPATCH, PATCH, and FETCH or configuration parameters. The CoAP iPATCH, PATCH, and FETCH
methods enable accessing and updating parts of a resource or multiple methods enable accessing and updating parts of a resource or multiple
resources with one request. This document defines new media types resources with one request. This document defines new media types
for the CoAP iPATCH, and FETCH methods for resources represented with for the CoAP iPATCH, PATCH, and FETCH methods for resources
the SenML data model. represented with the SenML data model.
Status of This Memo Status of This Memo
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Copyright Notice Copyright Notice
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document authors. All rights reserved. document authors. All rights reserved.
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Using FETCH and iPATCH with SenML . . . . . . . . . . . . . . 3 3. Using FETCH and (i)PATCH with SenML . . . . . . . . . . . . . 3
3.1. SenML FETCH . . . . . . . . . . . . . . . . . . . . . . . 3 3.1. SenML FETCH . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. SenML iPATCH . . . . . . . . . . . . . . . . . . . . . . 4 3.2. SenML (i)PATCH . . . . . . . . . . . . . . . . . . . . . 4
4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
5.1. CoAP Content-Format Registration . . . . . . . . . . . . 5 5.1. CoAP Content-Format Registration . . . . . . . . . . . . 6
5.2. senml-etch+json Media Type . . . . . . . . . . . . . . . 6 5.2. senml-etch+json Media Type . . . . . . . . . . . . . . . 6
5.3. senml-etch+cbor Media Type . . . . . . . . . . . . . . . 7 5.3. senml-etch+cbor Media Type . . . . . . . . . . . . . . . 7
6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 8
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
7.1. Normative References . . . . . . . . . . . . . . . . . . 8 7.1. Normative References . . . . . . . . . . . . . . . . . . 8
7.2. Informative References . . . . . . . . . . . . . . . . . 9 7.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
The Sensor Measurement Lists (SenML) media type {{RFC8428} and data The Sensor Measurement Lists (SenML) media type [RFC8428] and data
model can be used to transmit collections of resources, such as model can be used to transmit collections of resources, such as
batches of sensor data or configuration parameters. batches of sensor data or configuration parameters.
Example of a SenML collection is shown below: An example of a SenML collection is shown below:
[ [
{"bn":"2001:db8::2/3306/0/", "n":"5850", "vb":true}, {"bn":"2001:db8::2/3306/0/", "n":"5850", "vb":true},
{"n":"5851", "v":42}, {"n":"5851", "v":42},
{"n":"5750", "vs":"Ceiling light"} {"n":"5750", "vs":"Ceiling light"}
] ]
Here three resources "3306/0/5850", "3306/0/5851", and "3306/0/5750", Here three resources "3306/0/5850", "3306/0/5851", and "3306/0/5750",
of an IPSO dimmable light smart object [IPSO] are represented using a of an IPSO dimmable light smart object [IPSO] are represented using a
single SenML Pack with three SenML Records. All resources share the single SenML Pack with three SenML Records. All resources share the
same base name "2001:db8::2/3306/0/", hence full names for resources same base name "2001:db8::2/3306/0/", hence full names for resources
are "2001:db8::2/3306/0/5850", etc. are "2001:db8::2/3306/0/5850", etc.
The CoAP [RFC7252] iPATCH and FETCH methods [RFC8132] enable The CoAP [RFC7252] iPATCH, PATCH, and FETCH methods [RFC8132] enable
accessing and updating parts of a resource or multiple resources with accessing and updating parts of a resource or multiple resources with
one request. one request.
This document defines two new media types, one using the JavaScript This document defines two new media types, one using the JavaScript
Object Notation (JSON) [RFC8259] and one using the Concise Binary Object Notation (JSON) [RFC8259] and one using the Concise Binary
Object Representation (CBOR) [RFC7049], that can be used with the Object Representation (CBOR) [RFC7049], that can be used with the
CoAP iPATCH, PATCH, and FETCH methods for resources represented with CoAP iPATCH, PATCH, and FETCH methods for resources represented with
the SenML data model. The semantics of the new media types are the the SenML data model. The semantics of the new media types are the
same for the CoAP PATCH and iPATCH methods. same for the CoAP PATCH and iPATCH methods. The rest of the document
uses term "(i)PATCH" when referring to both methods.
2. Terminology 2. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
Readers should also be familiar with the terms and concepts discussed Readers should also be familiar with the terms and concepts discussed
skipping to change at page 3, line 35 skipping to change at page 3, line 36
Patch Record: One set of parameters similar to Fetch Record but also Patch Record: One set of parameters similar to Fetch Record but also
containing instructions on how to change existing SenML Pack(s). containing instructions on how to change existing SenML Pack(s).
Patch Pack: One or more Patch Records in an array structure. Patch Pack: One or more Patch Records in an array structure.
Target Record: A Record in a SenML Pack that is matching the Target Record: A Record in a SenML Pack that is matching the
selection criteria of a Fetch or Patch Record and hence is a selection criteria of a Fetch or Patch Record and hence is a
target for a Fetch or Patch operation. target for a Fetch or Patch operation.
3. Using FETCH and iPATCH with SenML (i)PATCH: A term that refers to both CoAP "PATCH" and "iPATCH"
methods when there is no difference in this specification in which
one is used.
The FETCH/iPATCH media types for SenML are modeled as extensions to 3. Using FETCH and (i)PATCH with SenML
The FETCH/(i)PATCH media types for SenML are modeled as extensions to
the SenML media type to enable re-use of existing SenML parsers and the SenML media type to enable re-use of existing SenML parsers and
generators, in particular on constrained devices. Unless mentioned generators, in particular on constrained devices. Unless mentioned
otherwise, FETCH and PATCH Packs are constructed with the same rules otherwise, FETCH and PATCH Packs are constructed with the same rules
and constraints as SenML Packs. The only difference to SenML media and constraints as SenML Packs.
type is allowing the use of "null" value for removing records with
the iPATCH method. The key difference to the SenML media type is allowing the use of a
"null" value for removing records with the (i)PATCH method. Also the
Fetch and Patch Records do not have default time or base version when
the fields are omitted.
3.1. SenML FETCH 3.1. SenML FETCH
The FETCH method can be used to select and return parts of one or The FETCH method can be used to select and return a subset of
more SenML Packs. The SenML Records are selected by giving the records, in sequence, of one or more SenML Packs. The SenML Records
name(s) of the resources using the SenML "name" and/or "base name" are selected by giving a set of names that, when resolved, match
Fields. resolved names in a SenML Pack. The names for a Fetch Pack are given
using the SenML "name" and/or "base name" Fields. The names are
resolved by concatenating the base name with the name field as
defined in [RFC8428].
For example, to select resources "5850" and "5851" from the example For example, to select the IPSO resources "5850" and "5851" from the
in Section 1, the following Fetch Pack can be used: example in Section 1, the following Fetch Pack can be used:
[ [
{"bn":"2001:db8::2/3306/0/", "n":"5850"}, {"bn":"2001:db8::2/3306/0/", "n":"5850"},
{"n":"5851"} {"n":"5851"}
] ]
The result to a FETCH request with the example above would be: The result to a FETCH request with the example above would be:
[ [
{"bn":"2001:db8::2/3306/0/", "n":"5850", "vb":true}, {"bn":"2001:db8::2/3306/0/", "n":"5850", "vb":true},
{"n":"5851", "v":42}, {"n":"5851", "v":42},
] ]
When SenML Records contain also time values, a name may no longer When SenML Records contain also time values, a name may no longer
uniquely identify a single Record. When no time is given in a Fetch uniquely identify a single Record. When no time is given in a Fetch
Record, all SenML Records with the given name are matched. When time Record, all SenML Records with the given name are matched (i.e.,
is given in the Fetch Record, only a SenML Record (if any) with equal unlike with SenML Records, lack of time field in a Fetch Record does
time value and name is matched. not imply time value zero). When time is given in the Fetch Record,
only a SenML Record (if any) with equal resolved time value and name
is matched.
The resolved form of records (Section 4.6 of [RFC8428]) is used when The resolved form of records (Section 4.6 of [RFC8428]) is used when
comparing the names and times of the Target and Fetch Records to comparing the names and times of the Target and Fetch Records to
accommodate for differences in use of the base values. accommodate for differences in use of the base values.
3.2. SenML iPATCH 3.2. SenML (i)PATCH
The iPATCH method can be used to change the values of SenML Records, The (i)PATCH method can be used to change the values of SenML
to add new Records, and to remove existing Records. The names and Records, to add new Records, and to remove existing Records. The
times of the Patch Records are given and matched in same way as for names and times of the Patch Records are given and matched in same
the Fetch Records, except each Patch Record can match at most one way as for the Fetch Records, except each Patch Record can match at
Target Record. Patch Packs can also include new values and other most one Target Record. Patch Packs can also include new values and
SenML Fields for the Records. other SenML Fields for the Records. Application of Patch Packs is
idempotent.
When the name in a Patch Record matches with the name in an existing When the name in a Patch Record matches with the name in an existing
Record, the time values are compared. If the time values do not Record, the resolved time values are compared. If the time values
exist or are equal in both Records, the Target Record is replaced either do not exist in both Records or are equal, the Target Record
with the contents of the Patch Record. is replaced with the contents of the Patch Record.
If a Patch Record contains a name, or combination of a time value and If a Patch Record contains a name, or combination of a time value and
a name, that do not exist in any existing Record in the Pack, the a name, that do not exist in any existing Record in the Pack, the
given Record, with all the fields it contains, is added to the Pack. given Record, with all the fields it contains, is added to the Pack.
If a Patch Record has a value field with value null, the matched If a Patch Record has a value field with value null, the matched
Record (if any) is removed from the Pack. Record (if any) is removed from the Pack.
For example, the following document could be given as iPATCH payload For example, the following document could be given as (i)PATCH
to change/set values of two SenML Records for the example in payload to change/set values of two SenML Records for the example in
Section 1: Section 1:
[ [
{"bn":"2001:db8::2/3306/0/", "n":"5850", "vb":false}, {"bn":"2001:db8::2/3306/0/", "n":"5850", "vb":false},
{"n":"5851", "v":10} {"n":"5851", "v":10}
] ]
If the request is successful, the resulting representation of the If the request is successful, the resulting representation of the
example SenML Pack would be as follows: example SenML Pack would be as follows:
[ [
{"bn":"2001:db8::2/3306/0/", "n":"5850", "vb":false}, {"bn":"2001:db8::2/3306/0/", "n":"5850", "vb":false},
{"n":"5851", "v":10}, {"n":"5851", "v":10},
{"n":"5750", "vs":"Ceiling light"} {"n":"5750", "vs":"Ceiling light"}
] ]
4. Security Considerations 4. Security Considerations
The security and privacy considerations of SenML apply also with the The security and privacy considerations of SenML apply also with the
FETCH and iPATCH methods. FETCH and (i)PATCH methods.
In FETCH and iPATCH requests, the client can pass arbitrary names to In FETCH and (i)PATCH requests, the client can pass arbitrary names
the target resource for manipulation. The resource implementer must to the target resource for manipulation. The resource implementer
take care to only allow access to names that are actually part of (or must take care to only allow access to names that are actually part
accessible through) the target resource. of (or accessible through) the target resource.
If the client is not allowed to do a GET or PUT on the full target If the client is not allowed to do a GET or PUT on the full target
resource (and thus all the names accessible through it), access resource (and thus all the names accessible through it), access
control rules must be evaluated for each record in the pack. control rules must be evaluated for each record in the pack.
5. IANA Considerations 5. IANA Considerations
This document registers two new media types and CoAP Content-Format This document registers two new media types and CoAP Content-Format
IDs for both media types. IDs for both media types.
skipping to change at page 6, line 26 skipping to change at page 6, line 42
Type name: application Type name: application
Subtype name: senml-etch+json Subtype name: senml-etch+json
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: Must be encoded as using a subset of the Encoding considerations: Must be encoded as using a subset of the
encoding allowed in [RFC8259]. See RFC-AAAA for details. This encoding allowed in [RFC8259]. This simplifies implementation of a
simplifies implementation of very simple system and does not impose very simple system and does not impose any significant limitations as
any significant limitations as all this data is meant for machine to all this data is meant for machine to machine communications and is
machine communications and is not meant to be human readable. not meant to be human readable.
Security considerations: See Section 4 of RFC-AAAA. Security considerations: See Section 4 of RFC-AAAA.
Interoperability considerations: Applications MUST ignore any key Interoperability considerations: Applications MUST ignore any key
value pairs that they do not understand unless the key ends with the value pairs that they do not understand unless the key ends with the
'_' character in which case an error MUST be generated. This allows '_' character in which case an error MUST be generated. This allows
backwards compatible extensions to this specification. backwards compatible extensions to this specification.
Published specification: RFC-AAAA Published specification: RFC-AAAA
skipping to change at page 7, line 30 skipping to change at page 7, line 46
5.3. senml-etch+cbor Media Type 5.3. senml-etch+cbor Media Type
Type name: application Type name: application
Subtype name: senml-etch+cbor Subtype name: senml-etch+cbor
Required parameters: none Required parameters: none
Optional parameters: none Optional parameters: none
Encoding considerations: Must be encoded as using [RFC7049]. See Encoding considerations: Must be encoded as using [RFC7049].
RFC-AAAA for details.
Security considerations: See Section 4 of RFC-AAAA. Security considerations: See Section 4 of RFC-AAAA.
Interoperability considerations: Applications MUST ignore any key Interoperability considerations: Applications MUST ignore any key
value pairs that they do not understand unless the key ends with the value pairs that they do not understand unless the key ends with the
'_' character in which case an error MUST be generated. This allows '_' character in which case an error MUST be generated. This allows
backwards compatible extensions to this specification. backwards compatible extensions to this specification.
Published specification: RFC-AAAA Published specification: RFC-AAAA
skipping to change at page 8, line 22 skipping to change at page 8, line 38
Intended usage: COMMON Intended usage: COMMON
Restrictions on usage: None Restrictions on usage: None
Author: Ari Keranen ari.keranen@ericsson.com Author: Ari Keranen ari.keranen@ericsson.com
Change controller: IESG Change controller: IESG
6. Acknowledgements 6. Acknowledgements
The use of FETCH and iPATCH methods with SenML was first introduced The use of FETCH and (i)PATCH methods with SenML was first introduced
by the OMA SpecWorks LwM2M v1.1 specification. This document by the OMA SpecWorks LwM2M v1.1 specification. This document
generalizes the use to any SenML representation. The authors would generalizes the use to any SenML representation. The authors would
like to thank Carsten Bormann, Christian Amsuess, Jaime Jimenez, like to thank Carsten Bormann, Christian Amsuess, Jaime Jimenez,
Klaus Hartke, and also everyone in the IETF CoRE and OMA SpecWorks Klaus Hartke, and other participants from the IETF CoRE and OMA
DMSE working groups for their contributions and reviews. SpecWorks DMSE working groups who have contributed ideas and reviews.
7. References 7. References
7.1. Normative References 7.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
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