CoRE Working Group K. Li
Internet-Draft Alibaba Group
Intended status: Standards Track A. Rahman
Expires: January 9, 2017 InterDigital
C. Bormann, Ed.
Universitaet Bremen TZI
July 08, 2016
Representing CoRE Groupcomm Formats in CBOR
draft-bormann-core-groupcomm-cbor-00
Abstract
Group Communication for the Constrained Application Protocol
(RFC7390) defines a number of JSON formats for controlling
communication between groups of nodes employing the Constrained
Application Protocol (CoAP). This specification defines CBOR
variants of these formats.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 9, 2017.
Copyright Notice
Copyright (c) 2016 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
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publication of this document. Please review these documents
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include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2
2. Group Communication Management Objects in CBOR . . . . . . . 3
2.1. Background . . . . . . . . . . . . . . . . . . . . . . . 3
2.2. Information Model . . . . . . . . . . . . . . . . . . . . 3
2.3. Mapping . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.4. Group Communication Example . . . . . . . . . . . . . . . 3
3. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
5. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Normative References . . . . . . . . . . . . . . . . . . 6
6.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
(See abstract for now.)
1.1. Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119] when they appear in ALL CAPS. These words may also appear
in this document in lower case as plain English words, absent their
normative meanings.
The term "byte" is used in its now customary sense as a synonym for
"octet".
CoAP: Constrained Application Protocol [RFC7252]
CBOR: Concise Binary Object Representation [RFC7049]
CoRE: Constrained RESTful Environments, the field of work underlying
[RFC6690], [RFC7049], [RFC7252], and [RFC7641]
IoT: Internet of Things
JSON: JavaScript Object Notation [RFC7159]
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2. Group Communication Management Objects in CBOR
2.1. Background
The CoAP Group Communications specification [RFC7390] defines group
management objects in JSON format. These objects are used to
represent IP multicast group information for CoAP endpoints. See
[I-D.ietf-core-resource-directory] for more examples of using these
objects.
2.2. Information Model
This section discusses the information model underlying the CoAP
Group Communication management object payload.
A group membership JSON object contains one or more key/value pairs,
and represents a single IP multicast group membership for the CoAP
endpoint. Each key/value pair is encoded as a member of the JSON
object, where the key is the member name and the value is the
member's value.
The information model of the CoAP Group Communication management
object can be summarized in CDDL [I-D.greevenbosch-appsawg-cbor-cddl]
below:
collection = { * index => membership }
index = tstr .regexp "[A-Za-z0-9]{1,2}"
membership = {
? n: groupname,
? a: groupaddress,
}
groupname = tstr ; host [":" port]
groupaddress = tstr ; IPv4address [ ":" port ]
; / "[" IPv6address "]" [":" port ]
Figure 1: CoAP Group Communication Data Model
2.3. Mapping
The objective of the mapping defined in this section is to map
information from the JSON formats specified in [RFC7390] into CBOR
format, using the rules of Section 4.2 of [RFC7049].
2.4. Group Communication Example
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{ "8" :{ "a": "[ff15::4200:f7fe:ed37:14ca]" },
"11":{ "n": "sensors.floor1.west.bldg6.example.com",
"a": "[ff15::4200:f7fe:ed37:25cb]" },
"12":{ "n": "All-Devices.floor1.west.bldg6.example.com",
"a": "[ff15::4200:f7fe:ed37:abcd]:4567" }
}
Figure 2: Example from section 2.6.2.4 of [RFC7390]
becomes:
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a3 # map(3)
61 # text(1)
38 # "8"
a1 # map(1)
61 # text(1)
61 # "a"
78 1b # text(27)
5b666631353a3a343230
303a663766653a656433
373a313463615d # "[ff15::4200:f7fe:ed37:14ca]"
62 # text(2)
3131 # "11"
a2 # map(2)
61 # text(1)
6e # "n"
78 25 # text(37)
73656e736f72732e666c
6f6f72312e776573742e
626c6467362e6578616d
706c652e636f6d # "sensors.floor1.west.bldg6.example.com"
61 # text(1)
61 # "a"
78 1b # text(27)
5b666631353a3a343230
303a663766653a656433
373a323563625d # "[ff15::4200:f7fe:ed37:25cb]"
62 # text(2)
3132 # "12"
a2 # map(2)
61 # text(1)
6e # "n"
78 29 # text(41)
416c6c2d446576696365
732e666c6f6f72312e77
6573742e626c6467362e
6578616d706c652e636f
6d # "All-Devices.floor1.west.bldg6.example.com"
61 # text(1)
61 # "a"
78 20 # text(32)
5b666631353a3a343230
303a663766653a656433
373a616263645d3a34353637 # "[ff15::4200:f7fe:ed37:abcd]:4567"
Figure 3: Group Communication Management Object Encoded in CBOR
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3. IANA Considerations
This specification registers the following additional Internet Media
Types:
TBD
4. Security Considerations
The security considerations relevant to the data models of [RFC7390],
as well as those of [RFC7049] and [RFC7159] apply.
5. Acknowledgements
Special thanks to Bert Greevenbosch who was an author on the initial
version of a contributing document as well as the original author on
the CDDL notation.
Hannes Tschofenig made many helpful suggestions for improving this
document, in particular splitting off the [RFC7390] parts from
[I-D.ietf-core-links-json].
6. References
6.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC6690] Shelby, Z., "Constrained RESTful Environments (CoRE) Link
Format", RFC 6690, DOI 10.17487/RFC6690, August 2012,
<http://www.rfc-editor.org/info/rfc6690>.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <http://www.rfc-editor.org/info/rfc7049>.
[RFC7159] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data
Interchange Format", RFC 7159, DOI 10.17487/RFC7159, March
2014, <http://www.rfc-editor.org/info/rfc7159>.
6.2. Informative References
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[I-D.greevenbosch-appsawg-cbor-cddl]
Vigano, C. and H. Birkholz, "CBOR data definition language
(CDDL): a notational convention to express CBOR data
structures", draft-greevenbosch-appsawg-cbor-cddl-08 (work
in progress), March 2016.
[I-D.ietf-core-links-json]
Li, K., Rahman, A., and D. Bormann, "Representing CoRE
Formats in JSON and CBOR", draft-ietf-core-links-json-05
(work in progress), April 2016.
[I-D.ietf-core-resource-directory]
Shelby, Z., Koster, M., Bormann, D., and P. Stok, "CoRE
Resource Directory", draft-ietf-core-resource-directory-08
(work in progress), July 2016.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014,
<http://www.rfc-editor.org/info/rfc7252>.
[RFC7390] Rahman, A., Ed. and E. Dijk, Ed., "Group Communication for
the Constrained Application Protocol (CoAP)", RFC 7390,
DOI 10.17487/RFC7390, October 2014,
<http://www.rfc-editor.org/info/rfc7390>.
[RFC7641] Hartke, K., "Observing Resources in the Constrained
Application Protocol (CoAP)", RFC 7641,
DOI 10.17487/RFC7641, September 2015,
<http://www.rfc-editor.org/info/rfc7641>.
Authors' Addresses
Kepeng LI
Alibaba Group
Wenyixi Road, Yuhang District
Hangzhou, Zhejiang 311121
China
Email: kepeng.lkp@alibaba-inc.com
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Akbar Rahman
InterDigital Communications, LLC
1000 Sherbrooke Street West
Montreal, Quebec H3A 3G4
Canada
Phone: +1-514-585-0761
Email: akbar.rahman@interdigital.com
Carsten Bormann (editor)
Universitaet Bremen TZI
Postfach 330440
Bremen D-28359
Germany
Phone: +49-421-218-63921
Email: cabo@tzi.org
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