Hypertext Transfer Protocol (HTTP): Conditional Requests
draft-ietf-httpbis-conditional-00

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HTTP Working Group                                      R. Fielding, Ed.
Internet-Draft                                                     Adobe
Obsoletes: 7232 (if approved)                         M. Nottingham, Ed.
Intended status: Standards Track                                  Fastly
Expires: October 5, 2018                                 J. Reschke, Ed.
                                                              greenbytes
                                                           April 3, 2018

        Hypertext Transfer Protocol (HTTP): Conditional Requests
                   draft-ietf-httpbis-conditional-00

Abstract

   The Hypertext Transfer Protocol (HTTP) is a stateless application-
   level protocol for distributed, collaborative, hypertext information
   systems.  This document defines HTTP/1.1 conditional requests,
   including metadata header fields for indicating state changes,
   request header fields for making preconditions on such state, and
   rules for constructing the responses to a conditional request when
   one or more preconditions evaluate to false.

   This document obsoletes RFC 7232.

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
   <http://lists.w3.org/Archives/Public/ietf-http-wg/>.

   Working Group information can be found at <http://httpwg.github.io/>;
   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 D.1.

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/.

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   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on October 5, 2018.

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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   Contributions published or made publicly available before November
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   than English.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     1.1.  Conformance and Error Handling  . . . . . . . . . . . . .   4
     1.2.  Syntax Notation . . . . . . . . . . . . . . . . . . . . .   4
   2.  Validators  . . . . . . . . . . . . . . . . . . . . . . . . .   4
     2.1.  Weak versus Strong  . . . . . . . . . . . . . . . . . . .   5
     2.2.  Last-Modified . . . . . . . . . . . . . . . . . . . . . .   6
       2.2.1.  Generation  . . . . . . . . . . . . . . . . . . . . .   7
       2.2.2.  Comparison  . . . . . . . . . . . . . . . . . . . . .   7
     2.3.  ETag  . . . . . . . . . . . . . . . . . . . . . . . . . .   8
       2.3.1.  Generation  . . . . . . . . . . . . . . . . . . . . .   9
       2.3.2.  Comparison  . . . . . . . . . . . . . . . . . . . . .  10
       2.3.3.  Example: Entity-Tags Varying on Content-Negotiated

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               Resources . . . . . . . . . . . . . . . . . . . . . .  10