Internet DRAFT - draft-bormann-cbor-cddl-csv
draft-bormann-cbor-cddl-csv
Network Working Group C. Bormann
Internet-Draft Universität Bremen TZI
Intended status: Standards Track H. Birkholz
Expires: 26 June 2024 Fraunhofer SIT
24 December 2023
Using CDDL for CSVs
draft-bormann-cbor-cddl-csv-04
Abstract
The Concise Data Definition Language (CDDL), standardized in RFC
8610, is defined to provide data models for data shaped like JSON or
CBOR.
Another representation format that is quote popular is the CSV
(Comma-Separated Values) file as defined by RFC 4180.
The present document shows a way how to use CDDL to provide a data
model for CSV files.
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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Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on 26 June 2024.
Copyright Notice
Copyright (c) 2023 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 (https://trustee.ietf.org/
license-info) in effect on the date of publication of this document.
Please review these documents carefully, as they describe your rights
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and restrictions with respect to this document. Code Components
extracted from this document must include Revised BSD License text as
described in Section 4.e of the Trust Legal Provisions and are
provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 2
2. CSV generic data model . . . . . . . . . . . . . . . . . . . 2
3. Examples . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security considerations . . . . . . . . . . . . . . . . . . . 5
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
6.1. Normative References . . . . . . . . . . . . . . . . . . 5
6.2. Informative References . . . . . . . . . . . . . . . . . 6
Appendix A. Example: ietf-system.sid represented in CSV . . . . 6
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
The Concise Data Definition Language (CDDL), standardized in
[RFC8610], is defined to provide data models for data shaped like
JSON or CBOR.
Another representation format that is quote popular is the CSV file
as defined by [RFC4180].
The present document shows how to use CDDL to provide a data model
for CSV files.
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.
This specification uses terminology from [RFC8610].
2. CSV generic data model
The CSV format is defined in [RFC4180]. The generic data model for
the data in a CSV file can be described in CDDL as:
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csv = [?header, *record]
header = [+header-field]
record = [+field]
header-field = text
field = text
Note that the elements of this data model describe the interpretation
of the data after processing and removal of lexical structure such as
newlines, commas, escape characters, and quotation marks.
For the purposes of a specific application, the data model level
structure of each field may be described in a more elaborate way,
e.g., as a number. A recent proposal,
[I-D.ietf-cbor-cddl-more-control], provides some CDDL control
operators that could be used to express the transformation between
the text string in the CSV field and the number that this text string
represents at the application data model level; this could be
explored in future revisions of this specification. For now, the
usage of anything but "text" for a field therefore MUST be
accompanied by an instruction how to perform the translation. As a
preferred choice, the JSON representation of the data model item, if
it exists, MAY be chosen by that instruction.
Since the CSV media type text/csv defaults to using the US-ASCII
character set (i.e., [STD80]; see Section 3 of [RFC4180]), many uses
of CSV will need to specify the media type parameter charset. (Note
that CDDL can describe text information that is in UTF-8 form, which
includes US-ASCII as that is a subset of UTF-8. If a different form
that is not a subset of UTF-8 is really still needed, some rules for
conversion will need to be defined by the application.)
The media type parameter header MAY be used to indicate the presence
or absence of a header line; if it is not given, the grammar MUST NOT
be ambiguous about the presence of a header (i.e., it MUST be either
mandatory or absent).
Note that the ABNF [STD68] in [RFC4180] does not quite handle the
case that charset is not us-ascii. For the purposes of the present
specification, the ABNF is understood to allow all characters from
the charset except %x22 and %x2C in TEXTDATA. For the purposes of
the present specification, the ABNF rule CRLF is read as:
CRLF = [CR] LF
as is hinted in Section 3 of [RFC4180].
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3. Examples
A simplified CSV form definition of a SID file [I-D.ietf-core-sid]
might look like this:
; header = absent
SID-File = [meta-record,
?description-record,
*dependency-record,
*range-record,
*item-record]
meta-record = ["ietf-sid-file",
module-name: text,
module-revision: empty / text,
sid-file-revision: empty / text,
sid-file-status: empty / "unpublished" / "published"]
description-record = ["description",
description: empty / text]
dependency-record = ["dependency",
module-name: text,
module-revision: text]
range-record = ["range",
entry-point: uint,
size: uint]
item-record = [; "item", -- useful to elide for bulk of file
sid: uint
(
namespace: "module" / "identity" / "feature"
identifier: yang-identifier
//
namespace: "data"
identifier: schema-node-path
)
status: empty / "stable" / "unstable" / "obsolete"]
yang-identifier = text .abnf ("yang-identifier" .det id-abnf)
schema-node-path = text .abnf ("schema-node-path" .det id-abnf)
id-abnf = '
schema-node-path = "/" QID *( "/" OQID)
yang-identifier = ID
QID = ID ":" ID
OQID = ID [":" ID]
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ID = I *C
I = "_" / %x41-5a / %x61-7a
C = I / %x30-39 / "-" / "."
'
empty = ""
This CDDL data model assumes that the text strings representing the
numbers entry-point, size, and sid are converted to uint. (Note
that, due to the way YANG-JSON [RFC7951] defines the representation
of uint64 data items, these actually are text strings in JSON, which
in CSV is indistinguishable from numbers. However, the CDDL model
for the CSV files will be more useful if it takes into account
typical CSV applications that automatically convert integer-like text
strings into numbers.)
The result of representing in CSV the sid file ietf-system.sid (as
defined in Appendix A of [I-D.ietf-core-sid]) is shown in Appendix A.
4. IANA Considerations
This document makes no requests of IANA.
5. Security considerations
The security considerations of [RFC8610] and [RFC4180] apply.
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,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC4180] Shafranovich, Y., "Common Format and MIME Type for Comma-
Separated Values (CSV) Files", RFC 4180,
DOI 10.17487/RFC4180, October 2005,
<https://www.rfc-editor.org/rfc/rfc4180>.
[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/rfc/rfc8174>.
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[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>.
[STD68] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234,
DOI 10.17487/RFC5234, January 2008,
<https://www.rfc-editor.org/rfc/rfc5234>.
6.2. Informative References
[I-D.ietf-cbor-cddl-more-control]
Bormann, C., "More Control Operators for CDDL", Work in
Progress, Internet-Draft, draft-ietf-cbor-cddl-more-
control-01, 7 December 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-cbor-
cddl-more-control-01>.
[I-D.ietf-core-sid]
Veillette, M., Pelov, A., Petrov, I., Bormann, C., and M.
Richardson, "YANG Schema Item iDentifier (YANG SID)", Work
in Progress, Internet-Draft, draft-ietf-core-sid-24, 22
December 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-core-sid-24>.
[RFC7951] Lhotka, L., "JSON Encoding of Data Modeled with YANG",
RFC 7951, DOI 10.17487/RFC7951, August 2016,
<https://www.rfc-editor.org/rfc/rfc7951>.
[RFC8792] Watsen, K., Auerswald, E., Farrel, A., and Q. Wu,
"Handling Long Lines in Content of Internet-Drafts and
RFCs", RFC 8792, DOI 10.17487/RFC8792, June 2020,
<https://www.rfc-editor.org/rfc/rfc8792>.
[STD80] Cerf, V., "ASCII format for network interchange", STD 80,
RFC 20, DOI 10.17487/RFC0020, October 1969,
<https://www.rfc-editor.org/rfc/rfc20>.
Appendix A. Example: ietf-system.sid represented in CSV
This appendix shows the CSV file that is automatically generated from
Appendix A of [I-D.ietf-core-sid]. (Note that plaintext-based RFCs
are limited to 72 columns; therefore five long lines in the CSV file
have been folded as defined in [RFC8792].)
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=============== NOTE: '\' line wrapping per RFC 8792 ================
ietf-sid-file,ietf-system,2014-08-06,,
description,Example sid file
dependency,ietf-yang-types,2013-07-15
dependency,ietf-inet-types,2013-07-15
dependency,ietf-netconf-acm,2018-02-14
dependency,iana-crypt-hash,2014-08-06
range,1700,100
1700,module,ietf-system,
1701,identity,authentication-method,
1702,identity,local-users,
1703,identity,radius,
1704,identity,radius-authentication-type,
1705,identity,radius-chap,
1706,identity,radius-pap,
1707,feature,authentication,
1708,feature,dns-udp-tcp-port,
1709,feature,local-users,
1710,feature,ntp,
1711,feature,ntp-udp-port,
1712,feature,radius,
1713,feature,radius-authentication,
1714,feature,timezone-name,
1715,data,/ietf-system:set-current-datetime,
1775,data,/ietf-system:set-current-datetime/input,
1776,data,/ietf-system:set-current-datetime/input/current-datetime,
1717,data,/ietf-system:system,
1718,data,/ietf-system:system-restart,
1719,data,/ietf-system:system-shutdown,
1720,data,/ietf-system:system-state,
1721,data,/ietf-system:system-state/clock,
1722,data,/ietf-system:system-state/clock/boot-datetime,
1723,data,/ietf-system:system-state/clock/current-datetime,
1724,data,/ietf-system:system-state/platform,
1725,data,/ietf-system:system-state/platform/machine,
1726,data,/ietf-system:system-state/platform/os-name,
1727,data,/ietf-system:system-state/platform/os-release,
1728,data,/ietf-system:system-state/platform/os-version,
1729,data,/ietf-system:system/authentication,
1730,data,/ietf-system:system/authentication/user,
1731,data,/ietf-system:system/authentication/user-authentication-\
order,
1732,data,/ietf-system:system/authentication/user/authorized-key,
1733,data,/ietf-system:system/authentication/user/authorized-key/\
algorithm,
1734,data,/ietf-system:system/authentication/user/authorized-key/key\
-data,
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1735,data,/ietf-system:system/authentication/user/authorized-key/\
name,
1736,data,/ietf-system:system/authentication/user/name,
1737,data,/ietf-system:system/authentication/user/password,
1738,data,/ietf-system:system/clock,
1739,data,/ietf-system:system/clock/timezone-name,
1740,data,/ietf-system:system/clock/timezone-utc-offset,
1741,data,/ietf-system:system/contact,
1742,data,/ietf-system:system/dns-resolver,
1743,data,/ietf-system:system/dns-resolver/options,
1744,data,/ietf-system:system/dns-resolver/options/attempts,
1745,data,/ietf-system:system/dns-resolver/options/timeout,
1746,data,/ietf-system:system/dns-resolver/search,
1747,data,/ietf-system:system/dns-resolver/server,
1748,data,/ietf-system:system/dns-resolver/server/name,
1749,data,/ietf-system:system/dns-resolver/server/udp-and-tcp,
1750,data,/ietf-system:system/dns-resolver/server/udp-and-tcp/\
address,
1751,data,/ietf-system:system/dns-resolver/server/udp-and-tcp/port,
1752,data,/ietf-system:system/hostname,
1753,data,/ietf-system:system/location,
1754,data,/ietf-system:system/ntp,
1755,data,/ietf-system:system/ntp/enabled,
1756,data,/ietf-system:system/ntp/server,
1757,data,/ietf-system:system/ntp/server/association-type,
1758,data,/ietf-system:system/ntp/server/iburst,
1759,data,/ietf-system:system/ntp/server/name,
1760,data,/ietf-system:system/ntp/server/prefer,
1761,data,/ietf-system:system/ntp/server/udp,
1762,data,/ietf-system:system/ntp/server/udp/address,
1763,data,/ietf-system:system/ntp/server/udp/port,
1764,data,/ietf-system:system/radius,
1765,data,/ietf-system:system/radius/options,
1766,data,/ietf-system:system/radius/options/attempts,
1767,data,/ietf-system:system/radius/options/timeout,
1768,data,/ietf-system:system/radius/server,
1769,data,/ietf-system:system/radius/server/authentication-type,
1770,data,/ietf-system:system/radius/server/name,
1771,data,/ietf-system:system/radius/server/udp,
1772,data,/ietf-system:system/radius/server/udp/address,
1773,data,/ietf-system:system/radius/server/udp/authentication-port,
1774,data,/ietf-system:system/radius/server/udp/shared-secret,
Acknowledgements
Rob Wilton, unknowingly, made us write this specification. We hope
it will be useful. Laurent Toutain inspired the SID CDDL format with
an example.
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Authors' Addresses
Carsten Bormann
Universität Bremen TZI
Postfach 330440
D-28359 Bremen
Germany
Phone: +49-421-218-63921
Email: cabo@tzi.org
Henk Birkholz
Fraunhofer SIT
Rheinstrasse 75
64295 Darmstadt
Germany
Email: henk.birkholz@sit.fraunhofer.de
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