Network Working Group M. Amundsen
Internet-Draft October 9, 2011
Intended status: Informational
Expires: April 11, 2012
The Item and Collection Link Relations
draft-amundsen-item-and-collection-link-relations-04
Abstract
RFC 5988 [RFC5988] standardized a means of indicating the
relationships between resources on the Web. This specification
defines a pair of reciprocal link relation types that may be used to
express the relationship between a collection and its members.
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Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the
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Internet-Draft The Item and Collection Link Relations October 2011
document authors. All rights reserved.
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1. Introduction
RFC 5988 [RFC5988] standardized a means of indicating the
relationships between resources on the Web. This specification
defines a pair of reciprocal link relation types that may be used to
express the relationship between a collection and its members.
These link relation types can be applied to a wide range of use cases
across multiple media types. For example, the 'collection' and
'item' link relation types are used in these media types:
1. OpenSearch 1.1: see Section 4.5.4.1 of [OpenSearch]
2. Maze+XML: see Section 3 of [Maze]
3. Collection+JSON: see Section 5 of [CollectionJSON]
2. Link Relations
The following link relations are defined.
2.1. 'item'
When included in a resource which represents a collection, the 'item'
link relation identifies a target resource that represents a member
of that collection.
For example, if a resource represents a catalog of products, that
same representation may include one or more links to resources which
represent members of that catalog.
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<html>
...
<h1>Product Group X Listing</h1>
...
<a href="..." rel="item">View Product X001</a>
<a href="..." rel="item">View Product X002</a>
...
</html>
or, in the case of a Link Header field
Link: <...>; rel="item"; title="View Product X001"
Link: <...>; rel="item"; title="View Product X002"
2.2. 'collection'
When included in a resource which represents a member of a
collection, the 'collection' link relation identifies a target
resource that represents a collection of which the context resource
is a member.
For example, if a resource represents a single product in a catalog,
that same representation may include a link to a resource which
represents a product group to which this single product belongs:
<a href="..." rel="collection">Return to Product Group X</a>
or, in the case of a Link Header field
Link: <...>; rel="collection"; title="Return to Product Group X"
Since it is possible that a resource could be a member of multiple
collections, multiple 'collection' link relations may appear within
the same representation:
<a href="..." rel="collection">View other widgets</a>
<a href="..." rel="collection">View all discontinued items</a>
The target resource representation need not be restricted to
representing a list. It may simply be a document that provides
details on the collection of which the context resource is a member:
Link: <...>; rel="collection";
title="Shakespeare's Collected Works - A History"
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3. IANA Considerations
IANA is asked to register the 'collection' and 'item' Link Relations
below as per [RFC5988].
3.1. 'item' Link Relation Registration
Relation Name:
item
Description:
The target IRI points to a resource that is a member of the
collection represented by the context IRI.
Reference:
See Section 2
3.2. 'collection' Link Relation Registration
Relation Name:
collection
Description:
The target IRI points to a resource which represents a collection
of which the context IRI is a member.
Reference:
See Section 2
4. Security Considerations
The two link relation types defined in this document are not believed
to introduce any new security issues to those which are discussed in
Section 7 of RFC5988 [RFC5988].
5. Internationalisation Considerations
The 'item' and 'collection' link relation types do not have any
internationalization considerations other than those which are
discussed in Section 8 of RFC5988 [RFC5988].
6. References
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6.1. Normative References
[RFC5988] Nottingham, M., "Web Linking", RFC 5988,
October 2010.
6.2. Informative References
[OpenSearch] Clinton, D., "Open Search 1.1", Work in Progress ,
March 2011, <http://www.opensearch.org/
Specifications/OpenSearch/1.1/>.
[Maze] Amundsen, M., "Maze+XML - Format", Web Page ,
December 2010,
<http://amundsen.com/media-types/maze/format/>.
[CollectionJSON] Amundsen, M., "Collection+JSON - Document Format",
Web Page , July 2011, <http://amundsen.com/
media-types/collection/format/>.
Appendix A. Acknowledgements
The author gratefully acknowledges the contributions of Julian
Reschke and Mykyta Yevstifeyev.
Author's Address
Mike Amundsen
EMail: mca@amundsen.com
URI: http://amundsen.com
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