Internet DRAFT - draft-keranen-core-senml-base-prefix
draft-keranen-core-senml-base-prefix
Network Working Group A. Keranen
Internet-Draft Ericsson
Intended status: Standards Track C. Amsuess
Expires: January 23, 2020 July 22, 2019
SenML Base Name Prefix Indication
draft-keranen-core-senml-base-prefix-00
Abstract
The Sensor Measurement Lists (SenML) media type uses globally unique
names to facilitate information exchange across systems. This
requirement often leads to long names and hence large amount of data
to be transmitted with each SenML Pack. This document defines an
efficient mechanism to indicate a globally unique prefix for names.
Status of This Memo
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Copyright Notice
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Indicating base name prefix . . . . . . . . . . . . . . . . . 3
3.1. IP address . . . . . . . . . . . . . . . . . . . . . . . 4
3.2. Request Base URI . . . . . . . . . . . . . . . . . . . . 4
3.3. Public key fingerprint . . . . . . . . . . . . . . . . . 4
3.4. TLS PSK Identity . . . . . . . . . . . . . . . . . . . . 5
3.5. CoRE Resource Directory endpoint ID . . . . . . . . . . . 5
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 6
6.1. Normative References . . . . . . . . . . . . . . . . . . 6
6.2. Informative References . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction
The Sensor Measurement Lists (SenML) media type [RFC8428] indicates
sources of information with globally unique names. A SenML Pack can
indicate "base names" ("bn" field) that are prefixed to all names
("n" fields) in the SenML Records where the "bn" appears and all
subsequent records until a new base name is indicated. Example of a
SenML Pack with two sources of measurement data that share a base
name is shown in Figure 1.
[
{"bn":"2001:db8:1234:5678::1/",
"n":"temperature", "u":"Cel", "v":25.2},
{"n":"humidity", "u":"%RH", "v":30}
]
Figure 1: SenML Pack with two sources of measurements
The base name construct enables indicating the globally unique part
of the name only once for a set of Records. However, the globally
unique part still needs to be indicated in each Pack. Since base
name is often relatively long, in some scenarios it would be useful
to be able to further compress or omit this information.
Since the sender and receiver of a SenML Pack often share context
information beyond what is in the SenML Pack, e.g., request URI when
a RESTful protocol is used, sender IP address, or security
association information. This information can be used to assist
constructing the globally unique part of a name. However, the sender
of the Pack needs to be able to indicate unambiguously what
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information is used and how the name is generated from that
information.
This document registers a new SenML field to indicate what
information outside of the SenML Pack should be used as a prefix to
the base name(s). Also rules for consistently creating SenML names
from this information is specified for each information source.
Since SenML has only a small set of characters that are allowed in
names (see Section 4.5.1 in [RFC8428]) replacing rules for characters
outside of this set (e.g., brackets and semicolons) are also defined.
2. 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
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
Readers should also be familiar with the terms and concepts discussed
in [RFC8428].
3. Indicating base name prefix
SenML field "bpi" contains an integer value that indicates what
information should be used by the receiver to construct a prefix to
the base names. This document defines following modes:
1: IPv4 or IPv6 address of the sender
2: IPv4 or IPv6 address and port of the sender
3: Base URI of the request URI
5: Fingerprint of the public key of the sender
6: TLS PSK Identity
10: CoRE Resource Directory endpoint ID
The following sub-sections define rules for generating SenML basename
prefix for each mode. Some rules require replacing characters from
the input identifiers with characters that are safe for SenML names.
Applying these rules may result in multiple different input
identifiers being mapped to the same output identifer. The sender of
the SenML Pack MUST ensure that such mapping does not result in
conflicting names from that sender.
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3.1. IP address
The SenML Pack sender IP address can be used without (mode 1) or with
(mode 2) port number to generate the base name prefix.
For IPv6 addresses the format defined in [RFC5952] without brackets
("[" and "]") MUST be used.
Example: "2001:db8::1"
For IPv6 address and port underscore ("_") for port separator MUST be
used.
Example: "2001:db8::1_5683"
For IPv4 addresses the "dot decimal" notation MUST be used.
Example: "192.0.2.1"
For IPv4 addresses colon (":") MUST be used for port separator.
Example: "192.0.2.1:5684"
3.2. Request Base URI
When a RESTful protocol (e.g., CoAP [RFC7252] or HTTP [RFC7230]) is
used to request a SenML Pack, the base of the target request URI can
be used as the base name prefix. If IP address is used in the
authority part of the URI, rules in Section 3.1 MUST be followed for
it.
Characters in the URI that are not in the character set allowed for
SenML names MUST be replaced with the underscore ("_") character.
Example: "coap://example.com/room1/"
3.3. Public key fingerprint
When X.509 certificate or raw public key is used to setup the
security association (e.g., a TLS connection) to retrieve a SenML
Pack, a fingerprint of the public key of the sender of the SenML Pack
can be used as the base name prefix. For a public key fingerprint
the "URL Segment Format" of [RFC6920] with ";" characters replaced
with "_" MUST be used.
Example: "sha-256_UyaQV-Ev4rdLoHyJJWCi11OHfrYv9E1aGQAlMO2X_-Q"
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3.4. TLS PSK Identity
When a pre-shared key (PSK) ciphersuites (e.g., [RFC4279])) are used
to establish a TLS connection, the PSK identity can be used as the
base name prefix. In this mode the PSK identity from the TLS
handshake with characters not allowed for SenML names replaced with
"_" MUST be used.
Example: "foo.example.com"
3.5. CoRE Resource Directory endpoint ID
When the sender has registered with the receiving system using the
CoRE Resource Directory [I-D.ietf-core-resource-directory] interface,
and has defined an "endpoint name" during the registration, the
endpoint name can be used as the base name prefix. Characters not
allowed for SenML names MUST be replaced with "_".
Example: "urn:dev:ow:10e2073a01080063"
4. IANA Considerations
IANA is requested to assign a new label in the "SenML Labels"
subregistry of the SenML registry [IANA.senml] (as defined in
[RFC8428]) for the "Base Name Prefix Indicator" as follows:
+-----------------------+-------+----------+---------+--------------+
| Name | Label | JSON | XML | Reference |
| | | Type | Type | |
+-----------------------+-------+----------+---------+--------------+
| Base Name Prefix | bpi | Number | int | this |
| Indicator | | | | document |
+-----------------------+-------+----------+---------+--------------+
IANA is requested to create a new "SenML Base Name Prefix Indicator
modes" subregistry to the SenML registry. Initial contents of the
subregistry is shown below:
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+-------------------+-------+---------------+
| Name | Value | Reference |
+-------------------+-------+---------------+
| IP address | 1 | this document |
| | | |
| IP address & port | 2 | this document |
| | | |
| Base URI | 3 | this document |
| | | |
| Public key | 5 | this document |
| | | |
| TLS PSK ID | 6 | this document |
| | | |
| CoRE RD endpoint | 10 | this document |
+-------------------+-------+---------------+
Acknowledgements
TBD
6. References
6.1. Normative References
[I-D.ietf-core-resource-directory]
Shelby, Z., Koster, M., Bormann, C., Stok, P., and C.
Amsuess, "CoRE Resource Directory", draft-ietf-core-
resource-directory-23 (work in progress), July 2019.
[IANA.senml]
IANA, "Sensor Measurement Lists (SenML)",
<http://www.iana.org/assignments/senml>.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>.
[RFC4279] Eronen, P., Ed. and H. Tschofenig, Ed., "Pre-Shared Key
Ciphersuites for Transport Layer Security (TLS)",
RFC 4279, DOI 10.17487/RFC4279, December 2005,
<https://www.rfc-editor.org/info/rfc4279>.
[RFC5952] Kawamura, S. and M. Kawashima, "A Recommendation for IPv6
Address Text Representation", RFC 5952,
DOI 10.17487/RFC5952, August 2010,
<https://www.rfc-editor.org/info/rfc5952>.
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[RFC6920] Farrell, S., Kutscher, D., Dannewitz, C., Ohlman, B.,
Keranen, A., and P. Hallam-Baker, "Naming Things with
Hashes", RFC 6920, DOI 10.17487/RFC6920, April 2013,
<https://www.rfc-editor.org/info/rfc6920>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/info/rfc8174>.
[RFC8428] Jennings, C., Shelby, Z., Arkko, J., Keranen, A., and C.
Bormann, "Sensor Measurement Lists (SenML)", RFC 8428,
DOI 10.17487/RFC8428, August 2018,
<https://www.rfc-editor.org/info/rfc8428>.
6.2. Informative References
[RFC7230] Fielding, R., Ed. and J. Reschke, Ed., "Hypertext Transfer
Protocol (HTTP/1.1): Message Syntax and Routing",
RFC 7230, DOI 10.17487/RFC7230, June 2014,
<https://www.rfc-editor.org/info/rfc7230>.
[RFC7252] Shelby, Z., Hartke, K., and C. Bormann, "The Constrained
Application Protocol (CoAP)", RFC 7252,
DOI 10.17487/RFC7252, June 2014,
<https://www.rfc-editor.org/info/rfc7252>.
Authors' Addresses
Ari Keranen
Ericsson
Jorvas 02420
Finland
Email: ari.keranen@ericsson.com
Christian Amsuess
Hollandstr. 12/4
1020
Austria
Phone: +43-664-9790639
Email: christian@amsuess.com
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