Internet-Draft CoRE Target Attribute Registry October 2022
Bormann Expires 26 April 2023 [Page]
Workgroup:
CoRE Working group
Internet-Draft:
draft-bormann-core-target-attr-00
Published:
Intended Status:
Informational
Expires:
Author:
C. Bormann
Universität Bremen TZI

CoRE Target Attribute Registry

Abstract

The Constrained RESTful Environments (CoRE) specifications apply Web technologies to constrained environments. One important such technology is Web Linking [RFC8288], which CoRE uses as the basis for a number of discovery protocols, such as the Link Format [RFC6690] in CoAP's Resource Discovery Protocol (Section 7 of [RFC7252]) and the Resource Directory [RFC9176].

Web Links can have Target Attributes, the names of which are not generally coordinated by the Web Linking specification (Section 2.2 of [RFC8288]). This short note introduces an IANA registry for coordinating names of Target Attributes when used in Constrained RESTful Environments.

About This Document

This note is to be removed before publishing as an RFC.

Status information for this document may be found at https://datatracker.ietf.org/doc/draft-bormann-core-target-attr/.

Discussion of this document takes place on the core Working Group mailing list (mailto:core@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/core/. Subscribe at https://www.ietf.org/mailman/listinfo/core/.

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 Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet-Drafts is at https://datatracker.ietf.org/drafts/current/.

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This Internet-Draft will expire on 26 April 2023.

Table of Contents

1. Introduction

(Please see abstract.)

The original Web Linking specification Section 3 of [RFC5988] did not attempt to coordinate names of target attributes except for providing common target attributes for use in the Link HTTP header. The current revision of that specification clarifies (Section 2.2 of [RFC8288]):

This specification does not attempt to coordinate the name of target attributes, their cardinality, or use. Those creating and maintaining serialisations SHOULD coordinate their target attributes to avoid conflicts in semantics or syntax and MAY define their own registries of target attributes.

This short note introduces an IANA registry for coordinating names of Target Attributes when used in Constrained RESTful Environments.

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 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here.

2. IANA Considerations

This specification defines a new sub-registry for Target Attributes in the CoRE Parameters registry [IANA.core-parameters], with the policy "expert review" (Section 4.5 of [BCP26]).

The expert is instructed to be frugal in the allocation of very short target attribute names, keeping them in reverse for applications that are likely to enjoy wide use and can make good use of their shortness. The expert is also instructed to direct the registrant to provide a specification (Section 4.6 of [BCP26]), but can make exceptions, for instance when a specification is not available at the time of registration but is likely forthcoming.

Each entry in the registry must include:

Attribute Name:

a lower case ASCII [STD90] string that starts with a letter and can contain digits and hyphen-minus characters afterwards ([a-z][-a-z0-9]*). (Note that [RFC8288] requires target attribute names to be interpreted in a case-insensitive way; the restriction to lower case here ensures that they are registered in a predictable form).

Brief description:

a brief description

Change Controller:

(see Section 2.3 of [BCP26])

Reference:

a reference document that provides a description of the target attribute, including the semantics for when the target attribute appears more than once in a link.

Initial entries in this sub-registry are as listed in Table 1:

Table 1: Initial Entries in the Target Attributes Registry
Attribute Name Brief description Change Controller Reference
href reserved (not useful as target attribute name) IESG [RFC6690]
anchor reserved (not useful as target attribute name) IESG [RFC6690]
rel reserved (not useful as target attribute name) IESG [RFC6690]
rev reserved (not useful as target attribute name) IESG [RFC6690]
hreflang (Web Linking) IESG [RFC8288]
media (Web Linking) IESG [RFC8288]
title (Web Linking) IESG [RFC8288]
type (Web Linking) IESG [RFC8288]
rt resource type IESG Section 3.1 of [RFC6690]
if interface description IESG Section 3.2 of [RFC6690]
sz maximum size estimate IESG Section 3.3 of [RFC6690]
ct Content-Format hint IESG Section 7.2.1 of [RFC7252]
obs observable resource IESG Section 6 of [RFC7641]
osc hint: resource only accessible using OSCORE IESG Section 9 of [RFC8613]
oscore-gid Group ID of the OSCORE Group (join resource of the Group Manager) IESG Section 3 of [I-D.tiloca-core-oscore-discovery]
app-gp endpoint name of the application group associated to the OSCORE Group (join resource of the Group Manager) IESG Section 3 of [I-D.tiloca-core-oscore-discovery]

A number of names are reserved as they are used for parameters in links other than target attributes, a further set is predefined in [RFC8288].

3. Security considerations

The security considerations of [RFC8288] apply, as do those of the discovery specifications [RFC6690], [RFC7252], and [RFC9176].

4. References

4.1. Normative References

[BCP26]
Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, , <https://www.rfc-editor.org/info/rfc8126>.
[IANA.core-parameters]
IANA, "Constrained RESTful Environments (CoRE) Parameters", , <https://www.iana.org/assignments/core-parameters>.
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, DOI 10.17487/RFC2119, , <https://www.rfc-editor.org/info/rfc2119>.
[RFC8174]
Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, , <https://www.rfc-editor.org/info/rfc8174>.
[RFC8288]
Nottingham, M., "Web Linking", RFC 8288, DOI 10.17487/RFC8288, , <https://www.rfc-editor.org/info/rfc8288>.
[STD90]
Cerf, V., "ASCII format for network interchange", STD 80, RFC 20, DOI 10.17487/RFC0020, , <https://www.rfc-editor.org/info/rfc20>.

4.2. Informative References

[I-D.tiloca-core-oscore-discovery]
Tiloca, M., Amsüss, C., and P. Van der Stok, "Discovery of OSCORE Groups with the CoRE Resource Directory", Work in Progress, Internet-Draft, draft-tiloca-core-oscore-discovery-12, , <https://www.ietf.org/archive/id/draft-tiloca-core-oscore-discovery-12.txt>.
[RFC5988]
Nottingham, M., "Web Linking", RFC 5988, DOI 10.17487/RFC5988, , <https://www.rfc-editor.org/info/rfc5988>.
[RFC6690]
Shelby, Z., "Constrained RESTful Environments (CoRE) Link Format", RFC 6690, DOI 10.17487/RFC6690, , <https://www.rfc-editor.org/info/rfc6690>.
[RFC7252]
Shelby, Z., Hartke, K., and C. Bormann, "The Constrained Application Protocol (CoAP)", RFC 7252, DOI 10.17487/RFC7252, , <https://www.rfc-editor.org/info/rfc7252>.
[RFC7641]
Hartke, K., "Observing Resources in the Constrained Application Protocol (CoAP)", RFC 7641, DOI 10.17487/RFC7641, , <https://www.rfc-editor.org/info/rfc7641>.
[RFC8613]
Selander, G., Mattsson, J., Palombini, F., and L. Seitz, "Object Security for Constrained RESTful Environments (OSCORE)", RFC 8613, DOI 10.17487/RFC8613, , <https://www.rfc-editor.org/info/rfc8613>.
[RFC9176]
Amsüss, C., Ed., Shelby, Z., Koster, M., Bormann, C., and P. van der Stok, "Constrained RESTful Environments (CoRE) Resource Directory", RFC 9176, DOI 10.17487/RFC9176, , <https://www.rfc-editor.org/info/rfc9176>.

Acknowledgements

TBD

Contributors

Jaime Jiménez
Ericsson

Jaime provided the list of initial registrations.

Author's Address

Carsten Bormann
Universität Bremen TZI
Postfach 330440
D-28359 Bremen
Germany