HTTP Caching
draft-ietf-httpbis-cache-03

Document Type Active Internet-Draft (httpbis WG)
Last updated 2018-10-18
Replaces draft-fielding-httpbis-http-cache
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HTTP Working Group                                      R. Fielding, Ed.
Internet-Draft                                                     Adobe
Obsoletes: 7234 (if approved)                         M. Nottingham, Ed.
Intended status: Standards Track                                  Fastly
Expires: April 21, 2019                                  J. Reschke, Ed.
                                                              greenbytes
                                                        October 18, 2018

                              HTTP Caching
                      draft-ietf-httpbis-cache-03

Abstract

   The Hypertext Transfer Protocol (HTTP) is a stateless application-
   level protocol for distributed, collaborative, hypertext information
   systems.  This document defines HTTP caches and the associated header
   fields that control cache behavior or indicate cacheable response
   messages.

   This document obsoletes RFC 7234.

Editorial Note

   This note is to be removed before publishing as an RFC.

   Discussion of this draft takes place on the HTTP working group
   mailing list (ietf-http-wg@w3.org), which is archived at
   <https://lists.w3.org/Archives/Public/ietf-http-wg/>.

   Working Group information can be found at <https://httpwg.org/>;
   source code and issues list for this draft can be found at
   <https://github.com/httpwg/http-core>.

   The changes in this draft are summarized in Appendix C.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
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at https://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

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   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 April 21, 2019.

Copyright Notice

   Copyright (c) 2018 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
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   include Simplified BSD License text as described in Section 4.e of
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   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
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   modifications of such material outside the IETF Standards Process.
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   than English.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   4
     1.1.  Requirements Notation . . . . . . . . . . . . . . . . . .   5
     1.2.  Syntax Notation . . . . . . . . . . . . . . . . . . . . .   5
     1.3.  Delta Seconds . . . . . . . . . . . . . . . . . . . . . .   5
   2.  Overview of Cache Operation . . . . . . . . . . . . . . . . .   6
   3.  Storing Responses in Caches . . . . . . . . . . . . . . . . .   7
     3.1.  Storing Incomplete Responses  . . . . . . . . . . . . . .   8
     3.2.  Storing Responses to Authenticated Requests . . . . . . .   8
     3.3.  Combining Partial Content . . . . . . . . . . . . . . . .   8
   4.  Constructing Responses from Caches  . . . . . . . . . . . . .   9
     4.1.  Calculating Secondary Keys with Vary  . . . . . . . . . .  10
     4.2.  Freshness . . . . . . . . . . . . . . . . . . . . . . . .  11
       4.2.1.  Calculating Freshness Lifetime  . . . . . . . . . . .  12
       4.2.2.  Calculating Heuristic Freshness . . . . . . . . . . .  13

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       4.2.3.  Calculating Age . . . . . . . . . . . . . . . . . . .  14
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