draft-ietf-httpbis-cache-01.txt		draft-ietf-httpbis-cache-02.txt
	HTTP Working Group R. Fielding, Ed.		HTTP Working Group R. Fielding, Ed.
	Internet-Draft Adobe		Internet-Draft Adobe
	Obsoletes: 7234 (if approved) M. Nottingham, Ed.		Obsoletes: 7234 (if approved) M. Nottingham, Ed.
	Intended status: Standards Track Fastly		Intended status: Standards Track Fastly
	Expires: December 2, 2018 J. Reschke, Ed.		Expires: January 3, 2019 J. Reschke, Ed.
	greenbytes		greenbytes
	May 31, 2018		July 2, 2018
	HTTP Caching		HTTP Caching
	draft-ietf-httpbis-cache-01		draft-ietf-httpbis-cache-02
	Abstract		Abstract
	The Hypertext Transfer Protocol (HTTP) is a stateless application-		The Hypertext Transfer Protocol (HTTP) is a stateless application-
	level protocol for distributed, collaborative, hypertext information		level protocol for distributed, collaborative, hypertext information
	systems. This document defines HTTP caches and the associated header		systems. This document defines HTTP caches and the associated header
	fields that control cache behavior or indicate cacheable response		fields that control cache behavior or indicate cacheable response
	messages.		messages.
	This document obsoletes RFC 7234.		This document obsoletes RFC 7234.
	skipping to change at page 1, line 36 ¶		skipping to change at page 1, line 36 ¶
	This note is to be removed before publishing as an RFC.		This note is to be removed before publishing as an RFC.
	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/>.		<https://lists.w3.org/Archives/Public/ietf-http-wg/>.
	Working Group information can be found at <https://httpwg.org/>;		Working Group information can be found at <https://httpwg.org/>;
	source code and issues list for this draft can be found at		source code and issues list for this draft can be found at
	<https://github.com/httpwg/http-core>.		<https://github.com/httpwg/http-core>.
	The changes in this draft are summarized in Appendix C.2.		The changes in this draft are summarized in Appendix C.3.
	Status of This Memo		Status of This Memo
	This Internet-Draft is submitted in full conformance with the		This Internet-Draft is submitted in full conformance with the
	provisions of BCP 78 and BCP 79.		provisions of BCP 78 and BCP 79.
	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 December 2, 2018.		This Internet-Draft will expire on January 3, 2019.
	Copyright Notice		Copyright Notice
	Copyright (c) 2018 IETF Trust and the persons identified as the		Copyright (c) 2018 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 3, line 45 ¶		skipping to change at page 3, line 45 ¶
	8.2. Cache Directive Registration . . . . . . . . . . . . . . 36		8.2. Cache Directive Registration . . . . . . . . . . . . . . 36
	8.3. Warn Code Registration . . . . . . . . . . . . . . . . . 36		8.3. Warn Code Registration . . . . . . . . . . . . . . . . . 36
	9. References . . . . . . . . . . . . . . . . . . . . . . . . . 36		9. References . . . . . . . . . . . . . . . . . . . . . . . . . 36
	9.1. Normative References . . . . . . . . . . . . . . . . . . 36		9.1. Normative References . . . . . . . . . . . . . . . . . . 36
	9.2. Informative References . . . . . . . . . . . . . . . . . 37		9.2. Informative References . . . . . . . . . . . . . . . . . 37
	Appendix A. Collected ABNF . . . . . . . . . . . . . . . . . . . 38		Appendix A. Collected ABNF . . . . . . . . . . . . . . . . . . . 38
	Appendix B. Changes from RFC 7234 . . . . . . . . . . . . . . . 39		Appendix B. Changes from RFC 7234 . . . . . . . . . . . . . . . 39
	Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 39		Appendix C. Change Log . . . . . . . . . . . . . . . . . . . . . 39
	C.1. Between RFC7234 and draft 00 . . . . . . . . . . . . . . 39		C.1. Between RFC7234 and draft 00 . . . . . . . . . . . . . . 39
	C.2. Since draft-ietf-httpbis-cache-00 . . . . . . . . . . . . 39		C.2. Since draft-ietf-httpbis-cache-00 . . . . . . . . . . . . 39
	Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39		C.3. Since draft-ietf-httpbis-cache-01 . . . . . . . . . . . . 39
			Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
	Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 42		Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 42
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 42
	1. Introduction		1. Introduction
	The Hypertext Transfer Protocol (HTTP) is a stateless application-		The Hypertext Transfer Protocol (HTTP) is a stateless application-
	level request/response protocol that uses extensible semantics and		level request/response protocol that uses extensible semantics and
	self-descriptive messages for flexible interaction with network-based		self-descriptive messages for flexible interaction with network-based
	hypertext information systems. HTTP is defined by a series of		hypertext information systems. HTTP is defined by a series of
	documents that collectively form the HTTP/1.1 specification:		documents that collectively form the HTTP/1.1 specification:
	skipping to change at page 29, line 46 ¶		skipping to change at page 29, line 46 ¶
	and is now maintained at <https://www.iana.org/assignments/http-		and is now maintained at <https://www.iana.org/assignments/http-
	cache-directives>.		cache-directives>.
	A registration MUST include the following fields:		A registration MUST include the following fields:
	o Cache Directive Name		o Cache Directive Name
	o Pointer to specification text		o Pointer to specification text
	Values to be added to this namespace require IETF Review (see		Values to be added to this namespace require IETF Review (see
	[RFC5226], Section 4.1).		[RFC8126], Section 4.8).
	5.3. Expires		5.3. Expires
	The "Expires" header field gives the date/time after which the		The "Expires" header field gives the date/time after which the
	response is considered stale. See Section 4.2 for further discussion		response is considered stale. See Section 4.2 for further discussion
	of the freshness model.		of the freshness model.
	The presence of an Expires field does not imply that the original		The presence of an Expires field does not imply that the original
	resource will change or cease to exist at, before, or after that		resource will change or cease to exist at, before, or after that
	time.		time.
	skipping to change at page 31, line 16 ¶		skipping to change at page 31, line 16 ¶
	pragma-directive = "no-cache" / extension-pragma		pragma-directive = "no-cache" / extension-pragma
	extension-pragma = token [ "=" ( token / quoted-string ) ]		extension-pragma = token [ "=" ( token / quoted-string ) ]
	When the Cache-Control header field is not present in a request,		When the Cache-Control header field is not present in a request,
	caches MUST consider the no-cache request pragma-directive as having		caches MUST consider the no-cache request pragma-directive as having
	the same effect as if "Cache-Control: no-cache" were present (see		the same effect as if "Cache-Control: no-cache" were present (see
	Section 5.2.1).		Section 5.2.1).
	When sending a no-cache request, a client ought to include both the		When sending a no-cache request, a client ought to include both the
	pragma and cache-control directives, unless Cache-Control: no-cache		pragma and cache-control directives, unless Cache-Control: no-cache
	is purposefully omitted to target other Cache-Control response		is purposefully omitted to target other Cache-Control request
	directives at HTTP/1.1 caches. For example:		directives at HTTP/1.1 caches. For example:
	GET / HTTP/1.1		GET / HTTP/1.1
	Host: www.example.com		Host: www.example.com
	Cache-Control: max-age=30		Cache-Control: max-age=30
	Pragma: no-cache		Pragma: no-cache
	will constrain HTTP/1.1 caches to serve a response no older than 30		will constrain HTTP/1.1 caches to serve a response no older than 30
	seconds, while precluding implementations that do not understand		seconds, while precluding implementations that do not understand
	Cache-Control from serving a cached response.		Cache-Control from serving a cached response.
	skipping to change at page 34, line 46 ¶		skipping to change at page 34, line 46 ¶
	A registration MUST include the following fields:		A registration MUST include the following fields:
	o Warn Code (3 digits)		o Warn Code (3 digits)
	o Short Description		o Short Description
	o Pointer to specification text		o Pointer to specification text
	Values to be added to this namespace require IETF Review (see		Values to be added to this namespace require IETF Review (see
	[RFC5226], Section 4.1).		[RFC8126], Section 4.8).
	6. History Lists		6. History Lists
	User agents often have history mechanisms, such as "Back" buttons and		User agents often have history mechanisms, such as "Back" buttons and
	history lists, that can be used to redisplay a representation		history lists, that can be used to redisplay a representation
	retrieved earlier in a session.		retrieved earlier in a session.
	The freshness model (Section 4.2) does not necessarily apply to		The freshness model (Section 4.2) does not necessarily apply to
	history mechanisms. That is, a history mechanism can display a		history mechanisms. That is, a history mechanism can display a
	previous representation even if it has expired.		previous representation even if it has expired.
	skipping to change at page 36, line 7 ¶		skipping to change at page 36, line 7 ¶
	quickly, thanks to the cache.		quickly, thanks to the cache.
	Note that the Set-Cookie response header field [RFC6265] does not		Note that the Set-Cookie response header field [RFC6265] does not
	inhibit caching; a cacheable response with a Set-Cookie header field		inhibit caching; a cacheable response with a Set-Cookie header field
	can be (and often is) used to satisfy subsequent requests to caches.		can be (and often is) used to satisfy subsequent requests to caches.
	Servers who wish to control caching of these responses are encouraged		Servers who wish to control caching of these responses are encouraged
	to emit appropriate Cache-Control response header fields.		to emit appropriate Cache-Control response header fields.
	8. IANA Considerations		8. IANA Considerations
	This section is to be removed before publishing as an RFC.
	The change controller for the following registrations is: "IETF		The change controller for the following registrations is: "IETF
	(iesg@ietf.org) - Internet Engineering Task Force".		(iesg@ietf.org) - Internet Engineering Task Force".
	8.1. Header Field Registration		8.1. Header Field Registration
	Please update the "Message Headers" registry of "Permanent Message		Please update the "Message Headers" registry of "Permanent Message
	Header Field Names" at <https://www.iana.org/assignments/message-		Header Field Names" at <https://www.iana.org/assignments/message-
	headers> with the header field names listed in the table of		headers> with the header field names listed in the table of
	Section 5.		Section 5.
	skipping to change at page 36, line 39 ¶		skipping to change at page 36, line 37 ¶
	registry at <https://www.iana.org/assignments/http-warn-codes> with		registry at <https://www.iana.org/assignments/http-warn-codes> with
	the registration procedure of Section 5.5.8 and the warn code values		the registration procedure of Section 5.5.8 and the warn code values
	summarized in the table of Section 5.5.		summarized in the table of Section 5.5.
	9. References		9. References
	9.1. Normative References		9.1. Normative References
	[Messaging]		[Messaging]
	Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,		Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
	Ed., "HTTP/1.1 Messaging", draft-ietf-httpbis-messaging-01		Ed., "HTTP/1.1 Messaging", draft-ietf-httpbis-messaging-02
	(work in progress), May 2018.		(work in progress), July 2018.
	[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate		[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
	Requirement Levels", BCP 14, RFC 2119,		Requirement Levels", BCP 14, RFC 2119,
	DOI 10.17487/RFC2119, March 1997,		DOI 10.17487/RFC2119, March 1997,
	<https://www.rfc-editor.org/info/rfc2119>.		<https://www.rfc-editor.org/info/rfc2119>.
	[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform		[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
	Resource Identifier (URI): Generic Syntax", STD 66,		Resource Identifier (URI): Generic Syntax", STD 66,
	RFC 3986, DOI 10.17487/RFC3986, January 2005,		RFC 3986, DOI 10.17487/RFC3986, January 2005,
	<https://www.rfc-editor.org/info/rfc3986>.		<https://www.rfc-editor.org/info/rfc3986>.
	[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax		[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
	Specifications: ABNF", STD 68, RFC 5234,		Specifications: ABNF", STD 68, RFC 5234,
	DOI 10.17487/RFC5234, January 2008,		DOI 10.17487/RFC5234, January 2008,
	<https://www.rfc-editor.org/info/rfc5234>.		<https://www.rfc-editor.org/info/rfc5234>.
	[Semantics]		[Semantics]
	Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,		Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
	Ed., "HTTP Semantics", draft-ietf-httpbis-semantics-01		Ed., "HTTP Semantics", draft-ietf-httpbis-semantics-02
	(work in progress), May 2018.		(work in progress), July 2018.
	[USASCII] American National Standards Institute, "Coded Character		[USASCII] American National Standards Institute, "Coded Character
	Set -- 7-bit American Standard Code for Information		Set -- 7-bit American Standard Code for Information
	Interchange", ANSI X3.4, 1986.		Interchange", ANSI X3.4, 1986.
	9.2. Informative References		9.2. Informative References
	[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,		[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
	Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext		Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
	Transfer Protocol -- HTTP/1.1", RFC 2616,		Transfer Protocol -- HTTP/1.1", RFC 2616,
	DOI 10.17487/RFC2616, June 1999,		DOI 10.17487/RFC2616, June 1999,
	<https://www.rfc-editor.org/info/rfc2616>.		<https://www.rfc-editor.org/info/rfc2616>.
	[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
	IANA Considerations Section in RFCs", BCP 26, RFC 5226,
	DOI 10.17487/RFC5226, May 2008,
	<https://www.rfc-editor.org/info/rfc5226>.
	[RFC5861] Nottingham, M., "HTTP Cache-Control Extensions for Stale		[RFC5861] Nottingham, M., "HTTP Cache-Control Extensions for Stale
	Content", RFC 5861, DOI 10.17487/RFC5861, April 2010,		Content", RFC 5861, DOI 10.17487/RFC5861, April 2010,
	<https://www.rfc-editor.org/info/rfc5861>.		<https://www.rfc-editor.org/info/rfc5861>.
	[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,		[RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch,
	"Network Time Protocol Version 4: Protocol and Algorithms		"Network Time Protocol Version 4: Protocol and Algorithms
	Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,		Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010,
	<https://www.rfc-editor.org/info/rfc5905>.		<https://www.rfc-editor.org/info/rfc5905>.
	[RFC6265] Barth, A., "HTTP State Management Mechanism", RFC 6265,		[RFC6265] Barth, A., "HTTP State Management Mechanism", RFC 6265,
	DOI 10.17487/RFC6265, April 2011,		DOI 10.17487/RFC6265, April 2011,
	<https://www.rfc-editor.org/info/rfc6265>.		<https://www.rfc-editor.org/info/rfc6265>.
	[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,		[RFC7234] Fielding, R., Ed., Nottingham, M., Ed., and J. Reschke,
	Ed., "Hypertext Transfer Protocol (HTTP): Caching",		Ed., "Hypertext Transfer Protocol (HTTP): Caching",
	RFC 7234, DOI 10.17487/RFC7234, June 2014,		RFC 7234, DOI 10.17487/RFC7234, June 2014,
	<https://www.rfc-editor.org/info/rfc7234>.		<https://www.rfc-editor.org/info/rfc7234>.
			[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
			Writing an IANA Considerations Section in RFCs", BCP 26,
			RFC 8126, DOI 10.17487/RFC8126, June 2017,
			<https://www.rfc-editor.org/info/rfc8126>.
	Appendix A. Collected ABNF		Appendix A. Collected ABNF
	In the collected ABNF below, list rules are expanded as per		In the collected ABNF below, list rules are expanded as per
	Section 11 of [Semantics].		Section 11 of [Semantics].
	Age = delta-seconds		Age = delta-seconds
	Cache-Control = *( "," OWS ) cache-directive *( OWS "," [ OWS		Cache-Control = *( "," OWS ) cache-directive *( OWS "," [ OWS
	cache-directive ] )		cache-directive ] )
	skipping to change at page 39, line 43 ¶		skipping to change at page 39, line 43 ¶
	C.2. Since draft-ietf-httpbis-cache-00		C.2. Since draft-ietf-httpbis-cache-00
	The changes are purely editorial:		The changes are purely editorial:
	o Moved all extensibility tips, registration procedures, and		o Moved all extensibility tips, registration procedures, and
	registry tables from the IANA considerations to normative		registry tables from the IANA considerations to normative
	sections, reducing the IANA considerations to just instructions		sections, reducing the IANA considerations to just instructions
	that will be removed prior to publication as an RFC.		that will be removed prior to publication as an RFC.
			C.3. Since draft-ietf-httpbis-cache-01
			o Cite RFC 8126 instead of RFC 5226 (<https://github.com/httpwg/
			http-core/issues/75>)
			o In Section 5.4, misleading statement about the relation between
			Pragma and Cache-Control (<https://github.com/httpwg/http-core/
			issues/92>, <https://www.rfc-editor.org/errata/eid4674>)
	Index		Index
	1		1
	110 (warn-code) 33		110 (warn-code) 33
	111 (warn-code) 33		111 (warn-code) 33
	112 (warn-code) 33		112 (warn-code) 33
	113 (warn-code) 34		113 (warn-code) 34
	199 (warn-code) 34		199 (warn-code) 34
	2		2
End of changes. 15 change blocks.
	20 lines changed or deleted		28 lines changed or added
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