Internet DRAFT - draft-bormann-cbor-edn-literals
draft-bormann-cbor-edn-literals
Network Working Group C. Bormann
Internet-Draft Universität Bremen TZI
Intended status: Informational 29 March 2023
Expires: 30 September 2023
Application-Oriented Literals in CBOR Extended Diagnostic Notation
draft-bormann-cbor-edn-literals-02
Abstract
The Concise Binary Object Representation, CBOR (RFC 8949), defines a
"diagnostic notation" in order to be able to converse about CBOR data
items without having to resort to binary data.
This document specifies how to add application-oriented extensions to
the diagnostic notation. It then defines two such extensions for the
use of CBOR diagnostic notation with CoRAL and Constrained Resource
Identifiers (draft-ietf-core-coral, draft-ietf-core-href).
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-cbor-edn-literals/.
Discussion of this document takes place on the cbor Working Group
mailing list (mailto:cbor@ietf.org), which is archived at
https://mailarchive.ietf.org/arch/browse/cbor/. Subscribe at
https://www.ietf.org/mailman/listinfo/cbor/.
Source for this draft and an issue tracker can be found at
https://github.com/cabo/edn-literal.
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
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This Internet-Draft will expire on 30 September 2023.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Application-Oriented Extension Literals . . . . . . . . . . . 3
3. The "cri" Extension . . . . . . . . . . . . . . . . . . . . . 4
4. The "dt" Extension . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5.1. CBOR Diagnostic Notation application extension identifiers
registry . . . . . . . . . . . . . . . . . . . . . . . . 5
5.2. Media Type . . . . . . . . . . . . . . . . . . . . . . . 5
5.3. Content-Format . . . . . . . . . . . . . . . . . . . . . 6
6. Security considerations . . . . . . . . . . . . . . . . . . . 7
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1. Normative References . . . . . . . . . . . . . . . . . . 7
7.2. Informative References . . . . . . . . . . . . . . . . . 7
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 8
1. Introduction
For the Concise Binary Object Representation, CBOR, Section 8 of
[RFC8949] in conjunction with Appendix G of [RFC8610] defines a
"diagnostic notation" in order to be able to converse about CBOR data
items without having to resort to binary data. Diagnostic notation
is based on JSON, with extensions for representing CBOR constructs
such as binary data and tags. (Standardizing this together with the
actual interchange format does not serve to create another
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interchange format, but enables the use of a shared diagnostic
notation in tools for and documents about CBOR.)
This document specifies how to add application-oriented extensions to
the diagnostic notation. It then defines two such extensions for the
use of CBOR diagnostic notation with CoRAL and Constrained Resource
Identifiers [I-D.ietf-core-coral] [I-D.ietf-core-href].
// Note that the Section 3 about CRIs may move to the
// [I-D.ietf-core-href] specification, depending on the relative
// speed of approval; the later document gets the section.
2. Application-Oriented Extension Literals
This document extends the syntax used in diagnostic notation for byte
string literals to also be available for application-oriented
extensions.
As per Section 8 of [RFC8949], the diagnostic notation can notate
byte strings in a number of [RFC4648] base encodings, where the
encoded text is enclosed in single quotes, prefixed by an identifier
(>h< for base16, >b32< for base32, >h32< for base32hex, >b64< for
base64 or base64url).
This syntax can be thought to establish a name space, with the names
"h", "b32", "h32", and "b64" taken, but other names being
unallocated. The present specification defines additional names for
this namespace, which we call _application-extension identifiers_.
For the quoted string, the same rules apply as for byte strings. In
particular, the escaping rules of JSON strings are applied
equivalently for application-oriented extensions, e.g., \\ stands for
a single backslash and \' stands for a single quote.
An application-extension identifier is a name consisting of a lower-
case ASCII letter (a-z) and zero or more additional ASCII characters
that are either lower-case letters or digits (a-z0-9).
Application-extension identifiers are registered in a registry
(Section 5.1). Prefixing a single-quoted string, an application-
extension identifier is used to build an application-oriented
extension literal, which stands for a CBOR data item the value of
which is derived from the text given in the single-quoted string
using a procedure defined in the specification for an application-
extension identifier.
Examples for application-oriented extensions to CBOR diagnostic
notation can be found in the following sections.
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In addition, this document finally registers a media type identifier
and a content-format for CBOR diagnostic notation. This does not
elevate its status as an interchange format, but recognizes that
interaction between tools is often smoother if media types can be
used.
3. The "cri" Extension
The application-extension identifier "cri" is used to notate a
Constrained Resource Identifier literal as per [I-D.ietf-core-href].
The text of the literal is a URI Reference as per [RFC3986] or an IRI
Reference as per [RFC3987].
The value of the literal is a CRI that can be converted to the text
of the literal using the procedure of Section 6.1 of
[I-D.ietf-core-href]. Note that there may be more than one CRI that
can be converted to the URI/IRI given; implementations are expected
to favor the simplest variant available and make non-surprising
choices otherwise.
As an example, the CBOR diagnostic notation
cri'https://example.com/bottarga/shaved'
is equivalent to
[-4, ["example", "com"], ["bottarga", "shaved"]]
4. The "dt" Extension
The application-extension identifier "dt" is used to notate a date/
time literal that can be used as an Epoch-Based Date/Time as per
Section 3.4.2 of [RFC8949].
The text of the literal is a Standard Date/Time String as per
Section 3.4.1 of [RFC8949].
The value of the literal is a number representing the result of a
conversion of the given Standard Date/Time String to an Epoch-Based
Date/Time. If fractional seconds are given in the text (production
time-fraction in Appendix A of [RFC3339]), the value is a floating-
point number; the value is an integer number otherwise.
As an example, the CBOR diagnostic notation
dt'1969-07-21T02:56:16Z'
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is equivalent to
-14159024
5. IANA Considerations
5.1. CBOR Diagnostic Notation application extension identifiers
registry
IANA is requested to create a registry [[where?]] for application-
extension identifiers, with the initial content shown in Table 1.
+=======================+=====================+===========+
| application-extension | description | reference |
| identifier | | |
+=======================+=====================+===========+
| h | Reserved | RFC8949 |
+-----------------------+---------------------+-----------+
| b32 | Reserved | RFC8949 |
+-----------------------+---------------------+-----------+
| h32 | Reserved | RFC8949 |
+-----------------------+---------------------+-----------+
| b64 | Reserved | RFC8949 |
+-----------------------+---------------------+-----------+
| cri | Constrained | RFCthis |
| | Resource Identifier | |
+-----------------------+---------------------+-----------+
| dt | Date/Time | RFCthis |
+-----------------------+---------------------+-----------+
Table 1: Initial Content of application extension
identifier registry
// (Define policy: probably specification required?; detailed
// template)
5.2. Media Type
IANA is requested to add the following Media-Type to the "Media
Types" registry [IANA.media-types].
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+=================+=============================+=============+
| Name | Template | Reference |
+=================+=============================+=============+
| cbor-diagnostic | application/cbor-diagnostic | RFC XXXX, |
| | | Section 5.2 |
+-----------------+-----------------------------+-------------+
Table 2: New Media Type application/cbor-diagnostic
Type name: application
Subtype name: cbor-diagnostic
Required parameters: N/A
Optional parameters: N/A
Encoding considerations: binary (UTF-8)
Security considerations: Section 6 of RFC XXXX
Interoperability considerations: none
Published specification: Section 5.2 of RFC XXXX
Applications that use this media type: Tools interchanging a human-
readable form of CBOR
Fragment identifier considerations: The syntax and semantics of
fragment identifiers is as specified for "application/cbor". (At
publication of RFC XXXX, there is no fragment identification
syntax defined for "application/cbor".)
Person & email address to contact for further information: CBOR WG
mailing list (cbor@ietf.org), or IETF Applications and Real-Time
Area (art@ietf.org)
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IETF
Provisional registration: no
5.3. Content-Format
IANA is requested to register a Content-Format number in the "CoAP
Content-Formats" sub-registry, within the "Constrained RESTful
Environments (CoRE) Parameters" Registry [IANA.core-parameters], as
follows:
+=============================+================+======+===========+
| Content-Type | Content Coding | ID | Reference |
+=============================+================+======+===========+
| application/cbor-diagnostic | - | TBD1 | RFC XXXX |
+-----------------------------+----------------+------+-----------+
Table 3: New Content-Format
TBD1 is to be assigned from the space 256..999.
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6. Security considerations
The security considerations of [RFC8949] and [RFC8610] apply.
// Anything else meaningful to say here?
7. References
7.1. Normative References
[I-D.ietf-core-href]
Bormann, C. and H. Birkholz, "Constrained Resource
Identifiers", Work in Progress, Internet-Draft, draft-
ietf-core-href-12, 6 March 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-core-
href-12>.
[IANA.media-types]
IANA, "Media Types",
<https://www.iana.org/assignments/media-types>.
[RFC3339] Klyne, G. and C. Newman, "Date and Time on the Internet:
Timestamps", RFC 3339, DOI 10.17487/RFC3339, July 2002,
<https://www.rfc-editor.org/rfc/rfc3339>.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", STD 66,
RFC 3986, DOI 10.17487/RFC3986, January 2005,
<https://www.rfc-editor.org/rfc/rfc3986>.
[RFC3987] Duerst, M. and M. Suignard, "Internationalized Resource
Identifiers (IRIs)", RFC 3987, DOI 10.17487/RFC3987,
January 2005, <https://www.rfc-editor.org/rfc/rfc3987>.
[RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data
Definition Language (CDDL): A Notational Convention to
Express Concise Binary Object Representation (CBOR) and
JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610,
June 2019, <https://www.rfc-editor.org/rfc/rfc8610>.
[RFC8949] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", STD 94, RFC 8949,
DOI 10.17487/RFC8949, December 2020,
<https://www.rfc-editor.org/rfc/rfc8949>.
7.2. Informative References
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[I-D.ietf-core-coral]
Amsüss, C. and T. Fossati, "The Constrained RESTful
Application Language (CoRAL)", Work in Progress, Internet-
Draft, draft-ietf-core-coral-05, 7 March 2022,
<https://datatracker.ietf.org/doc/html/draft-ietf-core-
coral-05>.
[IANA.core-parameters]
IANA, "Constrained RESTful Environments (CoRE)
Parameters",
<https://www.iana.org/assignments/core-parameters>.
[RFC4648] Josefsson, S., "The Base16, Base32, and Base64 Data
Encodings", RFC 4648, DOI 10.17487/RFC4648, October 2006,
<https://www.rfc-editor.org/rfc/rfc4648>.
Acknowledgements
The concept of application-oriented extensions to diagnostic
notation, as well as the definition for the "dt" extension were
inspired by the CoRAL work by Klaus Hartke.
Author's Address
Carsten Bormann
Universität Bremen TZI
Postfach 330440
D-28359 Bremen
Germany
Phone: +49-421-218-63921
Email: cabo@tzi.org
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