HTTP Client Hints
draft-ietf-httpbis-client-hints-08
HTTP Working Group I. Grigorik
Internet-Draft Y. Weiss
Intended status: Experimental Google
Expires: May 21, 2020 November 18, 2019
HTTP Client Hints
draft-ietf-httpbis-client-hints-08
Abstract
HTTP defines proactive content negotiation to allow servers to select
the appropriate response for a given request, based upon the user
agent's characteristics, as expressed in request headers. In
practice, clients are often unwilling to send those request headers,
because it is not clear whether they will be used, and sending them
impacts both performance and privacy.
This document defines an Accept-CH response header that servers can
use to advertise their use of request headers for proactive content
negotiation, along with a set of guidelines for the creation of such
headers, colloquially known as "Client Hints."
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/ [1].
Working Group information can be found at http://httpwg.github.io/
[2]; source code and issues list for this draft can be found at
https://github.com/httpwg/http-extensions/labels/client-hints [3].
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
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
Grigorik & Weiss Expires May 21, 2020 [Page 1]
Internet-Draft HTTP Client Hints November 2019
This Internet-Draft will expire on May 21, 2020.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4
2. Client Hint Request Header Fields . . . . . . . . . . . . . . 4
2.1. Sending Client Hints . . . . . . . . . . . . . . . . . . 4
2.2. Server Processing of Client Hints . . . . . . . . . . . . 5
3. Advertising Server Support . . . . . . . . . . . . . . . . . 5
3.1. The Accept-CH Response Header Field . . . . . . . . . . . 5
3.1.1. Interaction with Caches . . . . . . . . . . . . . . . 6
4. Security Considerations . . . . . . . . . . . . . . . . . . . 6
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
5.1. Accept-CH . . . . . . . . . . . . . . . . . . . . . . . . 7
6. References . . . . . . . . . . . . . . . . . . . . . . . . . 7
6.1. Normative References . . . . . . . . . . . . . . . . . . 7
6.2. Informative References . . . . . . . . . . . . . . . . . 8
6.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Appendix A. Interaction with Variants Response Header Field . . 9
Appendix B. Changes . . . . . . . . . . . . . . . . . . . . . . 9
B.1. Since -00 . . . . . . . . . . . . . . . . . . . . . . . . 9
B.2. Since -01 . . . . . . . . . . . . . . . . . . . . . . . . 9
B.3. Since -02 . . . . . . . . . . . . . . . . . . . . . . . . 9
B.4. Since -03 . . . . . . . . . . . . . . . . . . . . . . . . 9
B.5. Since -04 . . . . . . . . . . . . . . . . . . . . . . . . 10
B.6. Since -05 . . . . . . . . . . . . . . . . . . . . . . . . 10
B.7. Since -06 . . . . . . . . . . . . . . . . . . . . . . . . 10
B.8. Since -07 . . . . . . . . . . . . . . . . . . . . . . . . 10
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
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