Additional Link Relation Types
draft-snell-additional-link-relations-01

Network Working Group                                           J. Snell
Internet-Draft                                         February 24, 2012
Intended status: Standards Track
Expires: August 27, 2012

                     Additional Link Relation Types
                draft-snell-additional-link-relations-01

Abstract

   This specification defines a number of additional Link Relation
   Types.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

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   This Internet-Draft will expire on August 27, 2012.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  "implements"  . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  "privacy-policy"  . . . . . . . . . . . . . . . . . . . . . . . 3
   4.  "terms-of-service"  . . . . . . . . . . . . . . . . . . . . . . 4
   5.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   6.  Security Considerations . . . . . . . . . . . . . . . . . . . . 6
   7.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 6
     7.1.  Normative References  . . . . . . . . . . . . . . . . . . . 6
     7.2.  Informative References  . . . . . . . . . . . . . . . . . . 6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 6

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1.  Introduction

   This specification defines a number of additional Link Relation Types
   for a variety of common linking scenarios.

   In this document, the key words "MUST", "MUST NOT", "REQUIRED",
   "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY",
   and "OPTIONAL" are to be interpreted as described in [RFC2119].

2.  "implements"

   The "implements" Link relation can be used to refer to a resource
   that specifies the behavior implemented by the link's context.  Links
   using the "implements" link relation can point either to formal
   specification documents such as RFC's, Internet-Drafts, W3C
   Recommendations, or to informal and possibly vendor specific
   documents that describe implementation details.

   For example, an HTTP client that implements the Atom Publishing
   Protocol [RFC5023] could include an "implements" Link (per [RFC5988])
   within the HTTP Request referencing RFC 5023:

     POST /collection HTTP/1.1
     Host: example.org
     Content-Type: application/atom+xml; type=entry
     Link: <http://tools.ietf.org/html/rfc5023>; rel="implements"

     <entry ...

   Multiple "implements" Links can be used to indicate that multiple
   specifications have been implemented.

3.  "privacy-policy"

   The "privacy-policy" Link relation can be used to refer to a resource
   describing the privacy policy associated with the link's context.
   The privacy policy can be any resource that discloses what personal
   information about the user is collected, and how that personal
   information is stored, used, managed and disclosed to other parties.

   For example, an HTTP server that collects personal information about
   a user throughout the course of the user's interaction with the
   service can include "privacy-policy" Links within all HTTP Responses
   using any combination of Link headers or links embedded in the
   response payload:

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     HTTP/1.1 200 OK
     Content-Type: text/html
     Link: </privacy-policy.html>; rel="privacy-policy"

     <html>
       <head>
         ...
         <link rel="privacy-policy" href="/privacy-policy.html">
         ...
       </head>
       <body>
         ...
         <a rel="privacy-policy" href="/privacy-policy.html">
           Privacy Policy
         </a>
         ...
       </body>
     </html>

   Note that in the absence of clear legal obligations placed on an
   entity either through contract or law, the presence of a "privacy-
   policy" Link does not constitute a legally binding obligation on the
   part of the service.  The linked resource MUST be interpreted as only
   a description of the expected practice.

4.  "terms-of-service"

   The "terms-of-service" Link relation can be used to refer to a
   resource describing the Terms of Service associated with the link's
   context.  The Terms of Service can be any resource that describes the
   rules to which a consumer of the service must agree to follow when
   using the service provided by the link's context.

   For example, an HTTP server can include "terms-of-service" Links
   within all HTTP Responses using any combination of Link headers or
   links embedded in the response payload:

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     HTTP/1.1 200 OK
     Content-Type: text/html
     Link: </tos.html>; rel="terms-of-service"

     <html>
       <head>
         ...
         <link rel="terms-of-service" href="/tos.html">
         ...
       </head>
       <body>
         ...
         <a rel="terms-of-service" href="/tos.html">
           Privacy Policy
         </a>
         ...
       </body>
     </html>

   It must be noted that the Terms of Service linked to using this link
   relation carries no legal weight and can be ignored with impunity in
   the absence of an explicit, legally enforceable contract.  The linked
   Terms of Service are simply a notice of the terms that may be
   expected to apply once a contract is established.

5.  IANA Considerations

   The Registry of Link Relations should be updated with the following
   entries:

   o  Relation Name: implements
   o  Description: Refers to a specification implemented by the link's
      context.
   o  Reference: This specification.

   o  Relation Name: privacy-policy
   o  Description: Refers to a Privacy Policy associated with the link's
      context.
   o  Reference: This specification.

   o  Relation Name: terms-of-service
   o  Description: Refers to the Terms of Service associated with the
      link's context.
   o  Reference: This specification.

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6.  Security Considerations

   Implementors should note that the presence of a "privacy-policy" Link
   provides no guarantee that personal information collected and used by
   a resource will be handled in the manner described by the linked
   resource.

   Publishers of Privacy Policy resources linked to using the "privacy-
   policy" Link relation type SHOULD provide a clear and simple
   mechanism for signaling when changes to the Privacy Policy resource
   have been made, such as generating a new Entity Tag for the resource
   or generating a hash over the Privacy Policy's content.

   There are no additional security concerns introduced by the "terms-
   of-service" and "implements" Link relations.

7.  References

7.1.  Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

7.2.  Informative References

   [RFC5023]  Gregorio, J. and B. de hOra, "The Atom Publishing
              Protocol", RFC 5023, October 2007.

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

Author's Address

   James M Snell

   Email: jasnell@gmail.com

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