Cache Digests for HTTP/2
draft-ietf-httpbis-cache-digest-02
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Active Internet-Draft (httpbis WG)
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Last updated |
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2017-07-27
(latest revision 2017-05-29)
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draft-kazuho-h2-cache-digest
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IETF
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Intended RFC status |
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Experimental
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plain text
pdf
html
bibtex
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WG state
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In WG Last Call
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Document shepherd |
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Patrick McManus
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IESG state |
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I-D Exists
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Consensus Boilerplate |
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Yes
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Telechat date |
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Responsible AD |
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(None)
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Send notices to |
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Patrick McManus <mcmanus@ducksong.com>
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HTTP Working Group K. Oku
Internet-Draft DeNA Co, Ltd.
Intended status: Experimental M. Nottingham
Expires: December 1, 2017 May 30, 2017
Cache Digests for HTTP/2
draft-ietf-httpbis-cache-digest-02
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
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 http://httpwg.github.io/ ;
source code and issues list for this draft can be found at
https://github.com/httpwg/http-extensions/labels/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 December 1, 2017.
Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the
document authors. All rights reserved.
Oku & Nottingham Expires December 1, 2017 [Page 1]
Internet-Draft Cache Digests for HTTP/2 May 2017
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
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 . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 3
2. The CACHE_DIGEST Frame . . . . . . . . . . . . . . . . . . . 3
2.1. Client Behavior . . . . . . . . . . . . . . . . . . . . . 4
2.1.1. Computing the Digest-Value . . . . . . . . . . . . . 5
2.1.2. Computing a Hash Value . . . . . . . . . . . . . . . 6
2.2. Server Behavior . . . . . . . . . . . . . . . . . . . . . 7
2.2.1. Querying the Digest for a Value . . . . . . . . . . . 7
3. The ACCEPT_CACHE_DIGEST SETTINGS Parameter . . . . . . . . . 8
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9
5. Security Considerations . . . . . . . . . . . . . . . . . . . 10
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 10
6.1. Normative References . . . . . . . . . . . . . . . . . . 10
6.2. Informative References . . . . . . . . . . . . . . . . . 11
Appendix A. Encoding the CACHE_DIGEST frame as an HTTP Header . 12
Appendix B. Acknowledgements . . . . . . . . . . . . . . . . . . 13
Appendix C. Changes . . . . . . . . . . . . . . . . . . . . . . 13
C.1. Since draft-ietf-httpbis-cache-digest-01 . . . . . . . . 13
C.2. Since draft-ietf-httpbis-cache-digest-00 . . . . . . . . 13
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
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
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