draft-ietf-httpbis-client-hints-07.txt   draft-ietf-httpbis-client-hints-latest.txt 
HTTP Working Group I. Grigorik HTTP Working Group I. Grigorik
Internet-Draft Google Internet-Draft Google
Intended status: Experimental March 11, 2019 Intended status: Experimental May 16, 2019
Expires: September 12, 2019 Expires: November 17, 2019
HTTP Client Hints HTTP Client Hints
draft-ietf-httpbis-client-hints-07 draft-ietf-httpbis-client-hints-07
Abstract Abstract
HTTP defines proactive content negotiation to allow servers to select HTTP defines proactive content negotiation to allow servers to select
the appropriate response for a given request, based upon the user the appropriate response for a given request, based upon the user
agent's characteristics, as expressed in request headers. In agent's characteristics, as expressed in request headers. In
practice, clients are often unwilling to send those request headers, practice, clients are often unwilling to send those request headers,
because it is not clear whether they will be used, and sending them because it is not clear whether they will be used, and sending them
impacts both performance and privacy. impacts both performance and privacy.
This document defines two response headers, Accept-CH and Accept-CH- This document defines two response headers, Accept-CH and Accept-CH-
Lifetime, that servers can use to advertise their use of request Lifetime, that servers can use to advertise their use of request
headers for proactive content negotiation, along with a set of headers for proactive content negotiation, along with a set of
guidelines for the creation of such headers, colloquially known as guidelines for the creation of such headers, colloquially known as
"Client Hints." "Client Hints."
It also defines an initial set of Client Hints.
Note to Readers Note to Readers
Discussion of this draft takes place on the HTTP working group Discussion of this draft takes place on the HTTP working group
mailing list (ietf-http-wg@w3.org), which is archived at mailing list (ietf-http-wg@w3.org), which is archived at
https://lists.w3.org/Archives/Public/ietf-http-wg/ [1]. https://lists.w3.org/Archives/Public/ietf-http-wg/ [1].
Working Group information can be found at http://httpwg.github.io/ Working Group information can be found at http://httpwg.github.io/
[2]; source code and issues list for this draft can be found at [2]; source code and issues list for this draft can be found at
https://github.com/httpwg/http-extensions/labels/client-hints [3]. https://github.com/httpwg/http-extensions/labels/client-hints [3].
skipping to change at page 2, line 6 skipping to change at page 2, line 4
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/. Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on November 17, 2019.
This Internet-Draft will expire on September 12, 2019.
Copyright Notice Copyright Notice
Copyright (c) 2019 IETF Trust and the persons identified as the Copyright (c) 2019 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(https://trustee.ietf.org/license-info) in effect on the date of (https://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 2, line 34 skipping to change at page 2, line 31
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4 1.1. Notational Conventions . . . . . . . . . . . . . . . . . 4
2. Client Hint Request Header Fields . . . . . . . . . . . . . . 4 2. Client Hint Request Header Fields . . . . . . . . . . . . . . 4
2.1. Sending Client Hints . . . . . . . . . . . . . . . . . . 4 2.1. Sending Client Hints . . . . . . . . . . . . . . . . . . 4
2.2. Server Processing of Client Hints . . . . . . . . . . . . 5 2.2. Server Processing of Client Hints . . . . . . . . . . . . 5
2.2.1. Advertising Support via Accept-CH Header Field . . . 5 2.2.1. Advertising Support via Accept-CH Header Field . . . 5
2.2.2. The Accept-CH-Lifetime Header Field . . . . . . . . . 5 2.2.2. The Accept-CH-Lifetime Header Field . . . . . . . . . 5
2.2.3. Interaction with Caches . . . . . . . . . . . . . . . 6 2.2.3. Interaction with Caches . . . . . . . . . . . . . . . 6
3. Security Considerations . . . . . . . . . . . . . . . . . . . 7 3. Security Considerations . . . . . . . . . . . . . . . . . . . 6
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
4.1. Accept-CH . . . . . . . . . . . . . . . . . . . . . . . . 8 4.1. Accept-CH . . . . . . . . . . . . . . . . . . . . . . . . 7
4.2. Accept-CH-Lifetime . . . . . . . . . . . . . . . . . . . 8 4.2. Accept-CH-Lifetime . . . . . . . . . . . . . . . . . . . 8
5. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 5. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
5.1. Normative References . . . . . . . . . . . . . . . . . . 8 5.1. Normative References . . . . . . . . . . . . . . . . . . 8
5.2. Informative References . . . . . . . . . . . . . . . . . 9 5.2. Informative References . . . . . . . . . . . . . . . . . 9
5.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 9 5.3. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Appendix A. Interaction with Key Response Header Field . . . . . 9 Appendix A. Interaction with Key Response Header Field . . . . . 9
Appendix B. Changes . . . . . . . . . . . . . . . . . . . . . . 10 Appendix B. Changes . . . . . . . . . . . . . . . . . . . . . . 9
B.1. Since -00 . . . . . . . . . . . . . . . . . . . . . . . . 10 B.1. Since -00 . . . . . . . . . . . . . . . . . . . . . . . . 9
B.2. Since -01 . . . . . . . . . . . . . . . . . . . . . . . . 10 B.2. Since -01 . . . . . . . . . . . . . . . . . . . . . . . . 10
B.3. Since -02 . . . . . . . . . . . . . . . . . . . . . . . . 10 B.3. Since -02 . . . . . . . . . . . . . . . . . . . . . . . . 10
B.4. Since -03 . . . . . . . . . . . . . . . . . . . . . . . . 10 B.4. Since -03 . . . . . . . . . . . . . . . . . . . . . . . . 10
B.5. Since -04 . . . . . . . . . . . . . . . . . . . . . . . . 10 B.5. Since -04 . . . . . . . . . . . . . . . . . . . . . . . . 10
B.6. Since -05 . . . . . . . . . . . . . . . . . . . . . . . . 10 B.6. Since -05 . . . . . . . . . . . . . . . . . . . . . . . . 10
B.7. Since -06 . . . . . . . . . . . . . . . . . . . . . . . . 10 B.7. Since -06 . . . . . . . . . . . . . . . . . . . . . . . . 10
B.8. Since -07 . . . . . . . . . . . . . . . . . . . . . . . . 11 B.8. Since -07 . . . . . . . . . . . . . . . . . . . . . . . . 10
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 10
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 11
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 11
1. Introduction 1. Introduction
There are thousands of different devices accessing the web, each with There are thousands of different devices accessing the web, each with
different device capabilities and preference information. These different device capabilities and preference information. These
device capabilities include hardware and software characteristics, as device capabilities include hardware and software characteristics, as
well as dynamic user and client preferences. well as dynamic user and client preferences.
One way to infer some of these capabilities is through User-Agent One way to infer some of these capabilities is through User-Agent
 End of changes. 7 change blocks. 
13 lines changed or deleted 9 lines changed or added

This html diff was produced by rfcdiff 1.44jr. The latest version is available from http://tools.ietf.org/tools/rfcdiff/