


Network Working Group                                        M. Amundsen
Internet-Draft                                          February 5, 2012
Intended status: Informational
Expires: August 8, 2012


                 The Item and Collection Link Relations
          draft-amundsen-item-and-collection-link-relations-05

Abstract

   RFC 5988 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.

Editorial Note (To be removed by RFC Editor)

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   publication of this document.  Please review these documents



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   carefully, as they describe your rights and restrictions with respect
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   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

1.  Introduction

   RFC 5988 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.

   <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




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   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"

   It should also be noted that that same link might represent an 'item'
   in one collection as well as a 'collection' itself.  In this case
   both Link Relation values can be applied to the same link:

   Link: <...>; rel="collection item";
         title="A Review of Issac Asimov's Collected Works - Vol. I"

3.  IANA Considerations

   IANA is asked to register the 'collection' and 'item' Link Relations
   below as per [RFC5988].






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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 do not 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

6.1.  Normative References

   [RFC5988]         Nottingham, M., "Web Linking", RFC 5988,
                     October 2010.



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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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