HTTP Representation Variants
draft-nottingham-variants-01

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Network Working Group                                      M. Nottingham
Internet-Draft                                                    Fastly
Updates: 7234 (if approved)                             October 30, 2017
Intended status: Standards Track
Expires: May 3, 2018

                      HTTP Representation Variants
                      draft-nottingham-variants-01

Abstract

   This specification introduces the HTTP "Variants" response header
   field to communicate what representations are available for a given
   resource, and the companion "Variant-Key" response header field to
   indicate which representation was selected.  It is an augmentation of
   the "Vary" mechanism in HTTP caching.

Note to Readers

   _RFC EDITOR: please remove this section before publication_

   The issues list for this draft can be found at
   https://github.com/mnot/I-D/labels/variants [1].

   The most recent (often, unpublished) draft is at
   https://mnot.github.io/I-D/variants/ [2].

   Recent changes are listed at https://github.com/mnot/I-D/commits/gh-
   pages/variants [3].

   See also the draft's current status in the IETF datatracker, at
   https://datatracker.ietf.org/doc/draft-nottingham-variants/ [4].

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
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   Internet-Drafts are draft documents valid for a maximum of six months
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Nottingham                 Expires May 3, 2018                  [Page 1]
Internet-Draft        HTTP Representation Variants          October 2017

   This Internet-Draft will expire on May 3, 2018.

Copyright Notice

   Copyright (c) 2017 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
   (https://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
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Notational Conventions  . . . . . . . . . . . . . . . . .   4
   2.  The "Variants" HTTP Header Field  . . . . . . . . . . . . . .   4
     2.1.  Relationship to Vary  . . . . . . . . . . . . . . . . . .   6
   3.  The "Variant-Key" HTTP Header Field . . . . . . . . . . . . .   6
   4.  Defining Content Negotiation Using Variants . . . . . . . . .   7
   5.  Cache Behaviour . . . . . . . . . . . . . . . . . . . . . . .   7
     5.1.  Find Available Keys . . . . . . . . . . . . . . . . . . .   9
     5.2.  Example of Cache Behaviour  . . . . . . . . . . . . . . .   9
   6.  Example Headers . . . . . . . . . . . . . . . . . . . . . . .  10
     6.1.  Single Variant  . . . . . . . . . . . . . . . . . . . . .  10
     6.2.  Multiple Variants . . . . . . . . . . . . . . . . . . . .  11
     6.3.  Partial Coverage  . . . . . . . . . . . . . . . . . . . .  11
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  12
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  13
   9.  Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .  13
   10. References  . . . . . . . . . . . . . . . . . . . . . . . . .  13
     10.1.  Normative References . . . . . . . . . . . . . . . . . .  13
     10.2.  Informative References . . . . . . . . . . . . . . . . .  14
     10.3.  URIs . . . . . . . . . . . . . . . . . . . . . . . . . .  14
   Appendix A.  Variants for Existing Content Negotiation Mechanisms  14
     A.1.  Accept-Encoding . . . . . . . . . . . . . . . . . . . . .  14
     A.2.  Accept-Language . . . . . . . . . . . . . . . . . . . . .  15
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  15

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1.  Introduction
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