Internet DRAFT - draft-allen-newsml-urn-rfc3085bis
draft-allen-newsml-urn-rfc3085bis
Network Working Group D. Allen
Internet-Draft IPTC
Expires: Feb 25, 2003 September 24 2002
URN Namespace for NewsML Resources
draft-allen-newsml-urn-rfc3085bis-00.txt
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Copyright Notice
Copyright (C) The Internet Society (2000). All Rights Reserved.
Abstract
This document describes a URN (Uniform Resource Name) namespace for
identifying NewsML NewsItems and NewsML related XML Schemas. A NewsItem
is an information resource that is expressible as a NewsML element
within a NewsML document conforming to the NewsML Document Type
Declaration (DTD) as defined by the International Press Tele-
communications Council (IPTC).
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1. Introduction
NewsML is an XML format for packaging multimedia news resources. It
has been created under the auspices of the International Press
Telecommunications Council (IPTC), and version 1.0 was approved by
the IPTC on 6 October 2000.
The same logical NewsItem may exist in multiple physical locations.
The NewsML specification allows NewsItems to have multiple URLs, but
only a single URN. It is the latter which then uniquely names the
resource. This document obsoletes RFC 3085 (see Appendix A).
This namespace specification is for a formal namespace.
2. Specification Template
Namespace ID:
"newsml" requested.
Registration Information:
Registration Version Number: 1
Registration Date: 2002-12-07
Declared registrant of the namespace:
Name: International Press Telecommunications Council
Address: Royal Albert House
Sheet Street
Windsor
SL4 1BE
Contact: David Allen
m_director_iptc@iptc.org
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Declaration of syntactic structure:
The identifier has the following ABNF[6] specification:
(1) Either
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 = "(" / ")" / "+" / "," / "-" / "." / "=" / "@" / ";" /
"$" / "_" / "!" / "*" / "'"
escape = "%" HEXDIG HEXDIG
posint = posdig *DIGIT
posdig = "1" / "2" / "3" / "4" / "5" / "6" / "7" / "8" / "9"
The ProviderId must be an Internet domain name, and must be owned
by the organisation creating the NewsML resource and allocating
the URN to it, at the date identified by the DateId.
DateId is a date in ISO 8601 Basic Format (CCYYMMDD), and must
correspond to a date at which the organisation allocating the
URN owned the domain name specified in the ProviderId.
The NewsItemId must be unique among all NewsItems emanating from
the same provider and having the same DateId.
RevisionId is a positive integer indicating which revision of a
given NewsItem this is. Any positive integer may be used, but
it must always be the case that of two instances of a NewsItem
that have the same ProviderId, DateId and NewsItemId, the one
whose RevisionId has the larger value must be the more recent
revision. A RevisionId of 0 is not permitted.
If the NewsItem contains an "Update" element or elements, then
Update must be set to "U". If the NewsItem consists only of a
replacement set of NewsManagement data, then Update must be set
to "A". If neither of these is the case, then Update must be
suppressed.
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Or (2) - this is the form used for identifying an XML schema
NSS = ProviderId ":" DateId ":" FormatName
ProviderId = string
DateId = date
FormatName = string
date = century year month day
century = ( "0" posdig ) / ( posdig DIGIT )
year = 2DIGIT
month = ( 0 posdig ) / ( "1" ( "0" "1" "2" ) )
day = ( 0 posdig ) / ( ( "1" / "2" ) DIGIT ) / "30" / "31"
string = 1*char
char = ALPHA / DIGIT / symbol / escape
symbol = "(" / ")" / "+" / "," / "-" / "." / "=" / "@" / ";" /
"$" / "_" / "!" / "*" / "'"
escape = "%" HEXDIG HEXDIG
The ProviderId must be an Internet domain name, and must be
owned by the organisation creating the NewsML resource and
allocating the URN to it, at the date identified by the DateId.
In this case the allowed value is iptc.org
DateId is a date in ISO 8601 Basic Format (CCYYMMDD), and must
correspond to a date at which the organisation allocating the
URN owned the domain name specified in the ProviderId.
The FormatName must be unique among all FormatNames emanating from
the same provider and having the same DateId.
Initial FormatNames declared are NewsML, NITF and SportsML
Relevant ancillary documentation:
Definition of domain names, found in:
P. Mockapetris, "DOMAIN NAMES - IMPLEMENTATION AND SPECIFICATION",
RFC1035, November 1987.
Definition of NewsML structure found in:
"NewsML Functional Specification" 24 October 2000 published by IPTC
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Identifier uniqueness considerations:
The combination of ProviderId and DateId serves to uniquely
identify the organisation that is allocating the URN. That
organisation is responsible for ensuring the uniqueness of the
DateId/NewsItemId/RevisionId combination or the FormatName.
Uniqueness is guaranteed as long as the assigned string is never
reassigned for a given FQDN, and that the FQDN is never
reassigned.
N.B.: operationally, there is nothing that prevents a domain name
from being reassigned; indeed, it is not an uncommon occurrence.
This is one of the reasons that this example makes a poor URN
namespace in practice, and is therefore not seriously being
proposed as it stands.
Identifier persistence considerations:
A NewsML URN may only be allocated by an organisation that owns
an Internet domain name. The URN identifies a date on which
the organisation owned that domain name. The combination of
date and domain name will serve to uniquely identify that
organisation for all time.
Process of identifier assignment:
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 DateId.
Process of identifier resolution:
NewsML providers are responsible for the provision of a URN
resolution service, if any, for NewsML URNs they have assigned
with a valid ProviderId/DateId combination.
Rules for Lexical Equivalence:
URNs are lexically equivalent if the ProviderId, DateId,
NewsItemId, and RevisionId are all identical (case-insensitive
comparison).
Conformance with URN Syntax:
No special considerations beyond the syntax herein described.
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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:
Global (Option (1)).
The Option (2) of this specification will be used by the International
Press Telecommunications Council to define namespaces for its XML based
news exchange Schema such as NewsML, NITF and SportsML etc.
3. Examples
The following examples are representative of NewsML URNs, but may not
refer to actual resources.
urn:newsml:iptc.org:20001006:NewsMLv1.0:1
urn:newsml:reuters.com:20000206:
IIMFFH05643_2000-02-06_17-54-01_L06156584:1U
or
urn:newsml:iptc.org:20001006:NewsML
4. Namespace Considerations
RFC 3085 was designed to support the operational use of NewsML and
allow news providers to assign unique identifiers to NewsItems
transporting news content. Since the introduction of the XML Schema
it is necessary to provide a mechanism for allowing other news formats
to be imported into the NewsML structure in a way that allows
proper validation. The updated definition in this document specifies
an alternate form of the NewsML URN NID that may be used to
assign identifiers to these XML formats and to NewsML itself.
5. Security Considerations
There are no additional security considerations other than those
normally associated with the use and resolution of URNs in general.
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6. Community Considerations.
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 a 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.
7. IANA Considerations
This RFC includes an extended URN NID registration that is to be
entered into the IANA registry of URN NIDs.
The NID string "newsml" is requested. This was previously assigned
under RFC 3085 and meets the IETF constraints for URN naming.
References
[1] Rivers-Moore, D., "NewsML Version 1.0 Functional Specification",
November 2000,
<http://www.iptc.org/NewsML/specification/NewsMLv1.0.pdf>.
[2] Rivers-Moore, D., "NewsML Version 1.0 DTD", November 2000,
<http://www.iptc.org/NewsML/DTD/NewsMLv1.0.dtd>.
[3] W3C, XML WG, "Extensible Markup Language (XML) 1.0", February
1998, <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 YYYY, 2002.
[6] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", RFC 2234, November 1997.
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Author's Address
David Allen
IPTC
Royal Albert House
Sheet Street
Windsor SL4 1BE
United Kingdom
Phone: +44 17 53 70 50 51
EMail: m_director_iptc@iptc.org
Internet-Draft URN Namespace for NewsML September 2002
Appendix A
Reasons for Issue of New RFC
RFC 3085 issued in March 2001 specified the URN to be used when
identifying individual NewsML NewsItems. Since that time the use
of XML Schemas has become more common and it is now necessary to
provide a modified form of the original newsml URN to enable
individual Schemas to be properly identified. This new RFC seeks
to address this issue by:
1. Introducing a new alternative form of the newsml URN definition.
2. Updating the original definition to meet the new RFC template
recently issued by the IETF.(RFC YYYY)
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Acknowledgement
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