Concise Binary Object Representation (CBOR) Tag for Error Indications
draft-richter-cbor-error-tag-00
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Joerg Richter , Carsten Bormann | ||
| Last updated | 2019-01-29 | ||
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draft-richter-cbor-error-tag-00
Network Working Group J. Richter
Internet-Draft pdv Financial Software GmbH
Intended status: Informational C. Bormann
Expires: August 1, 2019 Universitaet Bremen TZI
January 28, 2019
Concise Binary Object Representation (CBOR) Tag for Error Indications
draft-richter-cbor-error-tag-00
Abstract
The Concise Binary Object Representation (CBOR, RFC 7049) is a data
format whose design goals include the possibility of extremely small
code size, fairly small message size, and extensibility without the
need for version negotiation.
In CBOR, one point of extensibility is the definition of CBOR tags.
While CBOR defines representations for null values and for an
undefined value, there is no convention for expressing errors or
exceptions in data structures, where the actual value desired could
not be calculated due to an error. The present specification defines
a tag for such error indications, enabling the addition of varying
levels of detail.
Note to Readers
Please discuss this draft on the mailing list cbor@ietf.org -
subscribe at https://www.ietf.org/mailman/listinfo/cbor to follow the
discussions.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Internet-Drafts are draft documents valid for a maximum of six months
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on August 1, 2019.
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Copyright Notice
Copyright (c) 2019 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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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. Error Format . . . . . . . . . . . . . . . . . . . . . . . . 3
3. CDDL typenames . . . . . . . . . . . . . . . . . . . . . . . 3
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 3
5. Security Considerations . . . . . . . . . . . . . . . . . . . 3
6. Normative References . . . . . . . . . . . . . . . . . . . . 4
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 4
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 4
1. Introduction
The Concise Binary Object Representation (CBOR, [RFC7049]) provides
for the interchange of structured data without a requirement for a
pre-agreed schema. RFC 7049 defines a basic set of data types, as
well as a tagging mechanism that enables extending the set of data
types supported via an IANA registry.
In CBOR, one point of extensibility is the definition of CBOR tags.
While CBOR defines representations for null values and for an
undefine value, there is no convention for expressing errors or
exceptions in data structures. The present specification defines a
tag for such error indications, enabling varying levels of detail.
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.
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2. Error Format
An error value is indicated by CBOR tag TBD101, which tags a data
item that may contain additional information about the error value:
o If no further information is provided, the data item is the CBOR
value null.
o If a diagnostic text string is provided, the data item is that
text string.
o If more detailed information is provided, the data item is a map
(CBOR major type 5), with text string or integer keys and values
as defined by the application.
3. CDDL typenames
For the use with the CBOR Data Definition Language, CDDL
[I-D.ietf-cbor-cddl], the type names defined in Figure 1 are
recommended:
error = error-of<(null / text / {* (int/tstr) => any})>
error-of<T> = #6.101(T)
Figure 1: Recommended type names for CDDL
4. IANA Considerations
In the registry [IANA.cbor-tags], IANA is requested to allocate the
tag in Table 1 from the FCFS space, with the present document as the
specification reference.
+--------+-----------------+----------------------------+
| Tag | Data Item | Semantics |
+--------+-----------------+----------------------------+
| TBD101 | null, text, map | [RFCthis] error indication |
+--------+-----------------+----------------------------+
Table 1: Values for Tags
5. Security Considerations
The security considerations of RFC 7049 apply; the tag introduced
here are not expected to raise security considerations beyond those.
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6. Normative References
[I-D.ietf-cbor-cddl]
Birkholz, H., Vigano, C., and C. Bormann, "Concise data
definition language (CDDL): a notational convention to
express CBOR and JSON data structures", draft-ietf-cbor-
cddl-06 (work in progress), November 2018.
[IANA.cbor-tags]
IANA, "Concise Binary Object Representation (CBOR) Tags",
<http://www.iana.org/assignments/cbor-tags>.
[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>.
[RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object
Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049,
October 2013, <https://www.rfc-editor.org/info/rfc7049>.
[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>.
Acknowledgements
Authors' Addresses
Joerg Richter
pdv Financial Software GmbH
Dorotheenstr. 64
Hamburg D-22301
Germany
Email: joerg.richter@pdv-fs.de
Carsten Bormann
Universitaet Bremen TZI
Postfach 330440
Bremen D-28359
Germany
Phone: +49-421-218-63921
Email: cabo@tzi.org
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