Cache Digests for HTTP/2
draft-kazuho-h2-cache-digest-00

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Last updated 2016-01-06
Replaced by draft-ietf-httpbis-cache-digest
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Network Working Group                                             K. Oku
Internet-Draft                                             DeNA Co, Ltd.
Intended status: Informational                             M. Nottingham
Expires: July 10, 2016                                   January 7, 2016

                        Cache Digests for HTTP/2
                    draft-kazuho-h2-cache-digest-00

Abstract

   This specification defines a HTTP/2 frame type to allow clients to
   inform the server of their cache's contents.  Servers can then use
   this to inform their choices of what to push to clients.

Note to Readers

   The issues list for this draft can be found at
   https://github.com/mnot/I-D/labels/h2-cache-digest .

   The most recent (often, unpublished) draft is at
   https://mnot.github.io/I-D/h2-cache-digest/ .

   Recent changes are listed at https://github.com/mnot/I-D/commits/gh-
   pages/h2-cache-digest .

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
   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 July 10, 2016.

Copyright Notice

   Copyright (c) 2016 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

Oku & Nottingham          Expires July 10, 2016                 [Page 1]
Internet-Draft          Cache Digests for HTTP/2            January 2016

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://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
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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.

Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Notational Conventions  . . . . . . . . . . . . . . . . .   3
   2.  The CACHE_DIGEST Frame  . . . . . . . . . . . . . . . . . . .   3
     2.1.  Computing the Digest-Value  . . . . . . . . . . . . . . .   3
   3.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   5
   4.  Security Considerations . . . . . . . . . . . . . . . . . . .   5
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   5
     5.1.  Normative References  . . . . . . . . . . . . . . . . . .   5
     5.2.  Informative References  . . . . . . . . . . . . . . . . .   6
   Appendix A.  Acknowledgements . . . . . . . . . . . . . . . . . .   6
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   6

1.  Introduction

   HTTP/2 [RFC7540] allows a server to "push" synthetic request/response
   pairs into a client's cache optimistically.  While there is strong
   interest in using this facility to improve perceived Web browsing
   performance, it is sometimes counterproductive because the client
   might already have cached the "pushed" response.

   When this is the case, the bandwidth used to "push" the response is
   effectively wasted, and represents opportunity cost, because it could
   be used by other, more relevant responses.  HTTP/2 allows a stream to
   be cancelled by a client using a RST_STREAM frame in this situation,
   but there is still at least one round trip of potentially wasted
   capacity even then.

   This specification defines a HTTP/2 frame type to allow clients to
   inform the server of their cache's contents using a Golumb-Rice Coded
   Set. Servers can then use this to inform their choices of what to
   push to clients.

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1.1.  Notational Conventions

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

2.  The CACHE_DIGEST Frame

   The CACHE_DIGEST frame type is 0xf1.  NOTE: This is an experimental
   value; if standardised, a permanent value will be assigned.

   A CACHE_DIGEST frame can be sent from a client to a server on any
   stream in the "open" state, and conveys a digest of the contents of
   the cache associated with that stream, as explained in Section 2.1.
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