HTTP/1.1, part 4: Conditional Requests
draft-ietf-httpbis-p4-conditional-19

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HTTPbis Working Group                                   R. Fielding, Ed.
Internet-Draft                                                     Adobe
Obsoletes: 2616 (if approved)                              Y. Lafon, Ed.
Intended status: Standards Track                                     W3C
Expires: September 13, 2012                              J. Reschke, Ed.
                                                              greenbytes
                                                          March 12, 2012

                 HTTP/1.1, part 4: Conditional Requests
                  draft-ietf-httpbis-p4-conditional-19

Abstract

   The Hypertext Transfer Protocol (HTTP) is an application-level
   protocol for distributed, collaborative, hypertext information
   systems.  HTTP has been in use by the World Wide Web global
   information initiative since 1990.  This document is Part 4 of the
   seven-part specification that defines the protocol referred to as
   "HTTP/1.1" and, taken together, obsoletes RFC 2616.

   Part 4 defines request header fields for indicating conditional
   requests and the rules for constructing responses to those requests.

Editorial Note (To be removed by RFC Editor)

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

   The current issues list is at
   <http://tools.ietf.org/wg/httpbis/trac/report/3> and related
   documents (including fancy diffs) can be found at
   <http://tools.ietf.org/wg/httpbis/>.

   The changes in this draft are summarized in Appendix C.20.

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

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   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 September 13, 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
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   publication of this document.  Please review these documents
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   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.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
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   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
     1.1.  Conformance and Error Handling . . . . . . . . . . . . . .  4
     1.2.  Syntax Notation  . . . . . . . . . . . . . . . . . . . . .  5
   2.  Validators . . . . . . . . . . . . . . . . . . . . . . . . . .  5
     2.1.  Weak versus Strong . . . . . . . . . . . . . . . . . . . .  5
     2.2.  Last-Modified  . . . . . . . . . . . . . . . . . . . . . .  7
       2.2.1.  Generation . . . . . . . . . . . . . . . . . . . . . .  7
       2.2.2.  Comparison . . . . . . . . . . . . . . . . . . . . . .  8
     2.3.  ETag . . . . . . . . . . . . . . . . . . . . . . . . . . .  9
       2.3.1.  Generation . . . . . . . . . . . . . . . . . . . . . . 10
       2.3.2.  Comparison . . . . . . . . . . . . . . . . . . . . . . 11
       2.3.3.  Example: Entity-tags varying on Content-Negotiated
               Resources  . . . . . . . . . . . . . . . . . . . . . . 11

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