Network Working Group M. Steidl
Internet-Draft IPTC
Intended status: Informational J. Lorenzen
Obsoletes: 3085 Businesswire
Expires: January 8, 2010 July 7, 2009
URN Namespace for news-related resources
draft-steidl-newsml-urn-rfc3085bis-00.txt
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Abstract
This document describes a URN (Uniform Resource Name) namespace for
identifying news-related data items. A news-related data item is an
information resource used for news exchange that is expressed as an
instance complying with a specific data schema. This may be the
schema of IPTC news standards specifications such as NewsML 1 and
the G2-Standards or the specification of any other body.
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Table of Contents
1. Introduction .................................................. 2
2. Specification Template ........................................ 2
3. Examples ...................................................... 5
4. Security Considerations ....................................... 5
5. Community Considerations ...................................... 6
6. IANA Considerations ........................................... 6
References ....................................................... 6
Author's addresses ............................................... 7
1. Introduction
NewsML 1 and the G2-Standards specify XML formats for packaging
multimedia news resources and items representing knowledge. These
standards have been created under the auspices of the International
Press Telecommunications Council (IPTC). Though the Namespace ID
specified by this RFC is "newsml", the URNs specified here are
intended for global use by any kind of news-related item. Their
intended use is not restricted to IPTC standards.
The same logical news-related data item may exist in multiple
physical locations. Specifications for such items - among them
NewsML 1 and the IPTC G2-Standards - allow for each item to have
multiple URLs to access and retrieve it, but only a single URN as an
identifier. It is the latter which uniquely identifies the resource.
This document obsoletes RFC 3085. The reasons for updating RFC 3085
are:
RFC 3085, issued in March 2001, specified the URN to be used when
identifying individual NewsML 1 NewsItems only. Since that time the
IPTC and other organisations have defined other news item formats
than NewsML 1 which also require identification and do so in a
slightly different way. This new RFC addresses this issue by
updating the original definition. This includes meeting the formal
requirements of the new RFC template for URN registrations issued by
the IETF (RFC 3406).
This namespace specification is for a formal namespace.
2. Specification Template
Namespace ID:
"newsml"
Registration Information:
Registration Version Number: 2
Registration Date: 2009-06-15
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Declared registrant of the namespace:
Name: International Press Telecommunications Council
Address: 20 Garrick Street
London WC2E 9BT
United Kingdom
Contact: Michael Steidl
office@iptc.org
http://www.iptc.org
Declaration of syntactic structure:
The identifier has the following ABNF[6] specification:
This is the form used for identifying a unique resource
in a NewsML instance.
NSS = ProviderId ":" DateId ":" NewsItemId
[":" RevisionId][Update]
ProviderId = string
DateId = date
NewsItemId = string
RevisionId = posint
Update = 0*1( "A" / "U" )
date = century year month day
century = ( "0" posdig ) / ( posdig DIGIT )
year = 2DIGIT
month = ( 0 posdig ) / ( "1" ( "0" "1" "2" ) )
day = ( 0 posdig ) / ( ( "1" / "2" ) DIGIT ) / "30" / "31"
string = 1*char
char = ALPHA / DIGIT / symbol / escape
symbol = "(" / ")" / "+" / "," / "-" / "." / "=" / "@" / ";" /
"$" / "_" / "!" / "*" / "'"
escape = "%" HEXDIG HEXDIG
posint = posdig *DIGIT
posdig = "1" / "2" / "3" / "4" / "5" / "6" / "7" / "8" / "9"
ProviderId must be a registered Internet domain name or a
subdomain name of such a domain, and must be registered, at the
date given in DateId, by the organisation creating the news
resource and allocating the URN to it.
DateId is a date in ISO 8601 Basic Format (CCYYMMDD), and must
correspond to a date at which the organisation allocating the
URN was the registered owner of the domain name specified in
the ProviderId.
NewsItemId must be unique among all news-related data items
emanating from the organisation with the same ProviderId
and having the same DateId.
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RevisionId is an optional positive integer indicating which
revision of a given data item this is. The use of the optional
RevisionId must be specified by the standard of the
corresponding data item. This includes requiring a mandatory
use of the RevisionId by the standard of the corresponding data
item. Any positive integer may be used as a RevisionId, but it
must always be the case that of two instances of a data item
that have the same ProviderId, DateId and NewsItemId, the one
whose RevisionId has the larger value must be the more recent
revision. A RevisionId of 0 is not permitted.
Update: when associated with NewsML 1 news items, if the news item
contains one or more NewsML 1 "Update" elements, then Update
must be set to "U". If the news item consists only of a
replacement set of NewsML 1 NewsManagement data, then Update
must be set to "A". If neither of these is the case, or if the
URN is not associated with a NewsML 1 news item, then Update
must be omitted.
Identifier uniqueness considerations:
The ProviderId plus the DateId serves to uniquely identify the
organisation that is allocating the URN by the requirement that
the domain name of the ProviderId is registered to the
organisation on the day of the DateId. That organisation is
responsible for ensuring the uniqueness of the NewsItemId and
for the use of any RevisionId in line with the specification of
the standard of the data item schema.
Identifier persistence considerations:
A newsml-URN may only be allocated by an organisation that is
registered with the Internet domain name of the ProviderId on
the day of the DateId. As a domain name can only be registered
to one organisation on a specific day the combination of date
and domain name will uniquely identify that organisation as
long as the information about this registration will be
available.
Process of identifier assignment:
For a newsml-URN identified data item the organisation identified
by the ProviderId/DateId combination is responsible for
allocating a NewsItemId that is unique among all those that it
allocates with that ProviderId/DateId.
Process of identifier resolution:
Any resolution mechanism for newsml-URNs is optional. Providers of
newsml-URN-identified data items are responsible for the
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provision of such a resolution service if they have decided to
provide one.
Rules for Lexical Equivalence:
Newsml-URNs are lexically equivalent if the ProviderId, DateId,
NewsItemId, and - if used - the optional RevisionId and Update
indicator are all identical (case-insensitive comparison).
Conformance with URN Syntax:
No special considerations beyond the syntax herein described.
Validation mechanism:
Organisations that allocate newsml-URNs are responsible for the
provision of a URN validation service, if any, for URNs they
have assigned with a valid ProviderId/DateId combination.
Scope:
Newsml-URNs are intended for global use by any kind of news-
related item.
3. Examples
The following examples are representative of NewsML URNs, but may not
refer to actual resources.
urn:newsml:businesswire.com:20010714:20070403005477
The example above identifies all versions of an IPTC G2 item - as
it omits the RevisionId
urn:newsml:pressassociation.press.net:20001017:nmhp-home_news-37896:1
The example above identifies the first revision of a
news item
urn:newsml:afp.com:20030704:AFP_TX_PAR_20030704_114814_IHB86:2A
The example above identifies the first revision of a NewsML 1
NewsItem with NewsManagement data only
urn:newsml:reuters.com:20000206:IIMFFH05643_2000-02-06_17-54-01:3U
The example above identifies the third revision of a NewsML 1
NewsItem with Updates elements only
4. Security Considerations
There are no additional security considerations other than those
normally associated with the use and resolution of URNs in general.
5. Community Considerations.
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The NewsML user community is moving towards the adoption of XML
Schema and the use of XML formats for marking up content that is not
suited to a pure textual form such as that in W3C XHTML or IPTC News
Industry Text Format (NITF). At present there is no consistent way
in which to refer to these other namespaces that may need to be
included within NewsML and are required to be identified in a manner
that allows proper validation of the complete document instance. The
introduction of an additional new form of the newsml-URN designed to
identify such XML Schema will provide such a mechanism. This will
enable users to properly resolve the relevant namespaces to identify
the Schemas in a consistent fashion.
6. IANA Considerations
This RFC includes an extended URN NID registration that is to be
entered into the IANA registry of URN NIDs as an update to the
existing registration of the NID string "newsml".
The NID string "newsml" is requested again. It was previously
assigned under RFC 3085 and meets the IETF constraints for URN
naming.
References
Normative References
[1] IPTC: NewsML 1 specifications
<http://www.newsml.org>
[2] IPTC: G2-Standards specifications
<http://www.g2-standards.org>
[3] W3C, XML WG, "Extensible Markup Language (XML) 1.0 (Fifth
Edition)", November 2008, <http://www.w3.org/TR/REC-xml>
[4] Moats, R., "URN Syntax", RFC 2141, May 1997.
[5] Daigle, L., van Gulik, D., Iannella, R. and P. Faltstrom, "URN
Namespace Definition Mechanisms", RFC 3406 and BCP 66,
October 2002.
[6] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
Informative References:
[7] P. Mockapetris, "DOMAIN NAMES - IMPLEMENTATION AND
SPECIFICATION", RFC1035, November 1987.
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Author's Address
Michael Steidl
IPTC
20 Garrick Street
London WC2E 9BT
United Kingdom
Email: mdirector@iptc.org
Jayson Lorenzen
Business Wire
44 Montgomery Street
San Francisco, CA 94104
USA
Email: Jayson.Lorenzen@businesswire.com
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