[Docs] [txt|pdf|xml|html] [Tracker] [Email] [Nits]

Versions: 00 01 02 RFC 6892

Network Working Group                                           E. Wilde
Internet-Draft                                           EMC Corporation
Intended status: Standards Track                           April 3, 2012
Expires: October 5, 2012


                   The 'describes' Link Relation Type
                     draft-wilde-describes-link-00

Abstract

   This specification defines the 'describes' link relation type that
   allows resource representations to indicate that they are describing
   another resource.  In contexts where applications want to associate
   described resources and description resources, and want to build
   services based on these associations, the 'describes' link relation
   type provides the opposite direction of the 'describedby' link
   relation type, which already is a registered link relation type.

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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   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 October 5, 2012.

Copyright Notice

   Copyright (c) 2012 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
   (http://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 and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of



Wilde                    Expires October 5, 2012                [Page 1]

Internet-Draft            "describes" Link Type               April 2012


   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Resource Descriptions . . . . . . . . . . . . . . . . . . . . . 3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
   6.  Change Log  . . . . . . . . . . . . . . . . . . . . . . . . . . 4
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 5
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 5
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . . . 5
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 5


































Wilde                    Expires October 5, 2012                [Page 2]

Internet-Draft            "describes" Link Type               April 2012


1.  Introduction

   Resources on the Web can be identified by an (registered) URI scheme
   and can be represented by any (registered) media type.  In many
   cases, applications establish specific (i.e., typed) relations
   between the resources they are concerned with, which can be under
   their control or controlled by another authority.  A common pattern
   for associating resources is to have resources which are descriptions
   of other resources.  This specification registers the 'describes'
   link relation which allows applications to represent the fact that
   one resource is a description of another resource.

   RFC 5988 [1] "defines a framework for typed links that isn't specific
   to a particular serialisation or application.  It does so by
   redefining the link relation registry established by Atom to have a
   broader domain, and adding to it the relations that are defined by
   HTML."


2.  Terminology

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [2].


3.  Resource Descriptions

   Associating resources with descriptions of these resources is a
   recurring pattern on the Web. The IANA link relation registry
   established by RFC 5988 [1] currently contains a 'describedby' link
   relation type, which has been registered by POWDER [3].  The
   definition given in that registration is as follows: "The
   relationship A 'describedby' B asserts that resource B provides a
   description of resource A. There are no constraints on the format or
   representation of either A or B, neither are there any further
   constraints on either resource."

   Since many scenarios using resource descriptions need to represent
   the fact that some resource describes a resource (the opposite of the
   'describedby' relation), this document registers a 'describes' link
   relation type.  Establishing a link A 'describes' B asserts that the
   resource identified by A is a description of the resource identified
   by B, without constraining in any way the identifiers being used for
   A and B, and the media types for the representations being provided,
   when those identifiers are dereferenced.  Specifically, it is
   possible that identifiers A and/or B have no associated interaction
   method (they could be URNs, for example), but it still is valid to



Wilde                    Expires October 5, 2012                [Page 3]

Internet-Draft            "describes" Link Type               April 2012


   establish the A 'describes' B link.

   Another design freedom is to use "chains" of 'describes' (or
   'describedby') links, so that one resource is a description of
   another resource, which in turn is a description of yet another
   resource.  The "levels" of descriptions can go as deep as required by
   an application, and are not constrained by this specification.


4.  IANA Considerations

   The link relation type below has been registered by IANA per Section
   6.2.1 of RFC 5988 [1]:

      Relation Name: describes

      Description: Identifying that a resource describes another
      resource, without making additional claims of the described or
      description resource.

      Reference: RFC xxxx (this draft's eventual RFC number)

      Notes: This link relation type is intended to be the inverse of
      the already 'describedby' relation type, thus allowing links to be
      established in both directions.


5.  Security Considerations

   Resource descriptions SHOULD never be treated as authoritative or
   exclusive without relying on additional mechanisms for trust and
   security.  Resources can have many (possible conflicting)
   descriptions, and the 'describes' link relation type makes no claim
   whatsoever about the authority of the party providing the association
   between the two resources, or about the authority of the party
   providing the description resource.


6.  Change Log

   Note to RFC Editor: Please remove this section before publication.


7.  References







Wilde                    Expires October 5, 2012                [Page 4]

Internet-Draft            "describes" Link Type               April 2012


7.1.  Normative References

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

   [2]  Bradner, S., "Key words for use in RFCs to Indicate Requirement
        Levels", RFC 2119, March 1997.

7.2.  Informative References

   [3]  Archer, P., Smith, K., and A. Perego, "Protocol for Web
        Description Resources (POWDER): Description Resources", World
        Wide Web Consortium Recommendation REC-powder-dr-20090901,
        September 2009,
        <http://www.w3.org/TR/2009/REC-powder-dr-20090901/>.


Appendix A.  Acknowledgements

   Thanks for comments and suggestions provided by ...


Author's Address

   Erik Wilde
   EMC Corporation
   6801 Koll Center Parkway
   Pleasanton, CA 94566
   U.S.A.

   Phone: +1-925-6006244
   Email: erik.wilde@emc.com
   URI:   http://dret.net/netdret/



















Wilde                    Expires October 5, 2012                [Page 5]


Html markup produced by rfcmarkup 1.109, available from https://tools.ietf.org/tools/rfcmarkup/