draft-ietf-httpbis-p6-cache-03.txt		draft-ietf-httpbis-p6-cache-04.txt
	Network Working Group R. Fielding, Ed.		Network Working Group R. Fielding, Ed.
	Internet-Draft Day Software		Internet-Draft Day Software
	Obsoletes: 2616 (if approved) J. Gettys		Obsoletes: 2616 (if approved) J. Gettys
	Intended status: Standards Track One Laptop per Child		Intended status: Standards Track One Laptop per Child
	Expires: December 19, 2008 J. Mogul		Expires: March 2, 2009 J. Mogul
	HP		HP
	H. Frystyk		H. Frystyk
	Microsoft		Microsoft
	L. Masinter		L. Masinter
	Adobe Systems		Adobe Systems
	P. Leach		P. Leach
	Microsoft		Microsoft
	T. Berners-Lee		T. Berners-Lee
	W3C/MIT		W3C/MIT
	Y. Lafon, Ed.		Y. Lafon, Ed.
	W3C		W3C
	J. Reschke, Ed.		J. Reschke, Ed.
	greenbytes		greenbytes
	June 17, 2008		August 29, 2008
	HTTP/1.1, part 6: Caching		HTTP/1.1, part 6: Caching
	draft-ietf-httpbis-p6-cache-03		draft-ietf-httpbis-p6-cache-04
	Status of this Memo		Status of this Memo
	By submitting this Internet-Draft, each author represents that any		By submitting this Internet-Draft, each author represents that any
	applicable patent or other IPR claims of which he or she is aware		applicable patent or other IPR claims of which he or she is aware
	have been or will be disclosed, and any of which he or she becomes		have been or will be disclosed, and any of which he or she becomes
	aware will be disclosed, in accordance with Section 6 of BCP 79.		aware will be disclosed, in accordance with Section 6 of BCP 79.
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF), its areas, and its working groups. Note that		Task Force (IETF), its areas, and its working groups. Note that
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	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."
	The list of current Internet-Drafts can be accessed at		The list of current Internet-Drafts can be accessed at
	http://www.ietf.org/ietf/1id-abstracts.txt.		http://www.ietf.org/ietf/1id-abstracts.txt.
	The list of Internet-Draft Shadow Directories can be accessed at		The list of Internet-Draft Shadow Directories can be accessed at
	http://www.ietf.org/shadow.html.		http://www.ietf.org/shadow.html.
	This Internet-Draft will expire on December 19, 2008.		This Internet-Draft will expire on March 2, 2009.
	Abstract		Abstract
	The Hypertext Transfer Protocol (HTTP) is an application-level		The Hypertext Transfer Protocol (HTTP) is an application-level
	protocol for distributed, collaborative, hypermedia information		protocol for distributed, collaborative, hypermedia information
	systems. HTTP has been in use by the World Wide Web global		systems. HTTP has been in use by the World Wide Web global
	information initiative since 1990. This document is Part 6 of the		information initiative since 1990. This document is Part 6 of the
	seven-part specification that defines the protocol referred to as		seven-part specification that defines the protocol referred to as
	"HTTP/1.1" and, taken together, obsoletes RFC 2616. Part 6 defines		"HTTP/1.1" and, taken together, obsoletes RFC 2616. Part 6 defines
	requirements on HTTP caches and the associated header fields that		requirements on HTTP caches and the associated header fields that
	skipping to change at page 4, line 20		skipping to change at page 4, line 20
	20.2. Informative References . . . . . . . . . . . . . . . . . . 44		20.2. Informative References . . . . . . . . . . . . . . . . . . 44
	Appendix A. Compatibility with Previous Versions . . . . . . . . 44		Appendix A. Compatibility with Previous Versions . . . . . . . . 44
	A.1. Changes from RFC 2068 . . . . . . . . . . . . . . . . . . 44		A.1. Changes from RFC 2068 . . . . . . . . . . . . . . . . . . 44
	A.2. Changes from RFC 2616 . . . . . . . . . . . . . . . . . . 45		A.2. Changes from RFC 2616 . . . . . . . . . . . . . . . . . . 45
	Appendix B. Change Log (to be removed by RFC Editor before		Appendix B. Change Log (to be removed by RFC Editor before
	publication) . . . . . . . . . . . . . . . . . . . . 45		publication) . . . . . . . . . . . . . . . . . . . . 45
	B.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 45		B.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 45
	B.2. Since draft-ietf-httpbis-p6-cache-00 . . . . . . . . . . . 45		B.2. Since draft-ietf-httpbis-p6-cache-00 . . . . . . . . . . . 45
	B.3. Since draft-ietf-httpbis-p6-cache-01 . . . . . . . . . . . 46		B.3. Since draft-ietf-httpbis-p6-cache-01 . . . . . . . . . . . 46
	B.4. Since draft-ietf-httpbis-p6-cache-02 . . . . . . . . . . . 46		B.4. Since draft-ietf-httpbis-p6-cache-02 . . . . . . . . . . . 46
			B.5. Since draft-ietf-httpbis-p6-cache-03 . . . . . . . . . . . 46
	Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46		Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 49		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 49
	Intellectual Property and Copyright Statements . . . . . . . . . . 52		Intellectual Property and Copyright Statements . . . . . . . . . . 52
	1. Introduction		1. Introduction
	HTTP is typically used for distributed information systems, where		HTTP is typically used for distributed information systems, where
	performance can be improved by the use of response caches, and		performance can be improved by the use of response caches, and
	includes a number of elements intended to make caching work as well		includes a number of elements intended to make caching work as well
	as possible. Because these elements interact with each other, it is		as possible. Because these elements interact with each other, it is
	skipping to change at page 38, line 42		skipping to change at page 38, line 42
	HTTP/1.1 caches SHOULD treat "Pragma: no-cache" as if the client had		HTTP/1.1 caches SHOULD treat "Pragma: no-cache" as if the client had
	sent "Cache-Control: no-cache". No new Pragma directives will be		sent "Cache-Control: no-cache". No new Pragma directives will be
	defined in HTTP.		defined in HTTP.
	Note: because the meaning of "Pragma: no-cache" as a response-		Note: because the meaning of "Pragma: no-cache" as a response-
	header field is not actually specified, it does not provide a		header field is not actually specified, it does not provide a
	reliable replacement for "Cache-Control: no-cache" in a response.		reliable replacement for "Cache-Control: no-cache" in a response.
	16.5. Vary		16.5. Vary
	The Vary field value indicates the set of request-header fields that		The Vary response-header field's value indicates the set of request-
	fully determines, while the response is fresh, whether a cache is		header fields that fully determines, while the response is fresh,
	permitted to use the response to reply to a subsequent request		whether a cache is permitted to use the response to reply to a
	without revalidation. For uncacheable or stale responses, the Vary		subsequent request without revalidation. For uncacheable or stale
	field value advises the user agent about the criteria that were used		responses, the Vary field value advises the user agent about the
	to select the representation. A Vary field value of "*" implies that		criteria that were used to select the representation. A Vary field
	a cache cannot determine from the request headers of a subsequent		value of "*" implies that a cache cannot determine from the request
	request whether this response is the appropriate representation. See		headers of a subsequent request whether this response is the
	Section 8 for use of the Vary header field by caches.		appropriate representation. See Section 8 for use of the Vary header
			field by caches.
	Vary = "Vary" ":" ( "*" | 1#field-name )		Vary = "Vary" ":" ( "*" | 1#field-name )
	An HTTP/1.1 server SHOULD include a Vary header field with any		An HTTP/1.1 server SHOULD include a Vary header field with any
	cacheable response that is subject to server-driven negotiation.		cacheable response that is subject to server-driven negotiation.
	Doing so allows a cache to properly interpret future requests on that		Doing so allows a cache to properly interpret future requests on that
	resource and informs the user agent about the presence of negotiation		resource and informs the user agent about the presence of negotiation
	on that resource. A server MAY include a Vary header field with a		on that resource. A server MAY include a Vary header field with a
	non-cacheable response that is subject to server-driven negotiation,		non-cacheable response that is subject to server-driven negotiation,
	since this might provide the user agent with useful information about		since this might provide the user agent with useful information about
	the dimensions over which the response varies at the time of the		the dimensions over which the response varies at the time of the
	response.		response.
	skipping to change at page 43, line 27		skipping to change at page 43, line 27
	[ISO-8859-1]		[ISO-8859-1]
	International Organization for Standardization,		International Organization for Standardization,
	"Information technology -- 8-bit single-byte coded graphic		"Information technology -- 8-bit single-byte coded graphic
	character sets -- Part 1: Latin alphabet No. 1", ISO/		character sets -- Part 1: Latin alphabet No. 1", ISO/
	IEC 8859-1:1998, 1998.		IEC 8859-1:1998, 1998.
	[Part1] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,		[Part1] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
	Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,		Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
	and J. Reschke, Ed., "HTTP/1.1, part 1: URIs, Connections,		and J. Reschke, Ed., "HTTP/1.1, part 1: URIs, Connections,
	and Message Parsing", draft-ietf-httpbis-p1-messaging-03		and Message Parsing", draft-ietf-httpbis-p1-messaging-04
	(work in progress), June 2008.		(work in progress), August 2008.
	[Part2] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,		[Part2] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
	Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,		Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
	and J. Reschke, Ed., "HTTP/1.1, part 2: Message		and J. Reschke, Ed., "HTTP/1.1, part 2: Message
	Semantics", draft-ietf-httpbis-p2-semantics-03 (work in		Semantics", draft-ietf-httpbis-p2-semantics-04 (work in
	progress), June 2008.		progress), August 2008.
	[Part3] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,		[Part3] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
	Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,		Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
	and J. Reschke, Ed., "HTTP/1.1, part 3: Message Payload		and J. Reschke, Ed., "HTTP/1.1, part 3: Message Payload
	and Content Negotiation", draft-ietf-httpbis-p3-payload-03		and Content Negotiation", draft-ietf-httpbis-p3-payload-04
	(work in progress), June 2008.		(work in progress), August 2008.
	[Part4] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,		[Part4] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
	Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,		Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
	and J. Reschke, Ed., "HTTP/1.1, part 4: Conditional		and J. Reschke, Ed., "HTTP/1.1, part 4: Conditional
	Requests", draft-ietf-httpbis-p4-conditional-03 (work in		Requests", draft-ietf-httpbis-p4-conditional-04 (work in
	progress), June 2008.		progress), August 2008.
	[Part5] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,		[Part5] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
	Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,		Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
	and J. Reschke, Ed., "HTTP/1.1, part 5: Range Requests and		and J. Reschke, Ed., "HTTP/1.1, part 5: Range Requests and
	Partial Responses", draft-ietf-httpbis-p5-range-03 (work		Partial Responses", draft-ietf-httpbis-p5-range-04 (work
	in progress), June 2008.		in progress), August 2008.
	[Part7] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,		[Part7] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
	Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,		Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
	and J. Reschke, Ed., "HTTP/1.1, part 7: Authentication",		and J. Reschke, Ed., "HTTP/1.1, part 7: Authentication",
	draft-ietf-httpbis-p7-auth-03 (work in progress),		draft-ietf-httpbis-p7-auth-04 (work in progress),
	June 2008.		August 2008.
	[RFC2047] Moore, K., "MIME (Multipurpose Internet Mail Extensions)		[RFC2047] Moore, K., "MIME (Multipurpose Internet Mail Extensions)
	Part Three: Message Header Extensions for Non-ASCII Text",		Part Three: Message Header Extensions for Non-ASCII Text",
	RFC 2047, November 1996.		RFC 2047, November 1996.
	[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, March 1997.		Requirement Levels", BCP 14, RFC 2119, March 1997.
	20.2. Informative References		20.2. Informative References
	skipping to change at page 46, line 39		skipping to change at page 46, line 39
	other parts of the specification.		other parts of the specification.
	B.4. Since draft-ietf-httpbis-p6-cache-02		B.4. Since draft-ietf-httpbis-p6-cache-02
	Ongoing work on IANA Message Header Registration		Ongoing work on IANA Message Header Registration
	(<http://www3.tools.ietf.org/wg/httpbis/trac/ticket/40>):		(<http://www3.tools.ietf.org/wg/httpbis/trac/ticket/40>):
	o Reference RFC 3984, and update header registrations for headers		o Reference RFC 3984, and update header registrations for headers
	defined in this document.		defined in this document.
			B.5. Since draft-ietf-httpbis-p6-cache-03
			Closed issues:
			o <http://www3.tools.ietf.org/wg/httpbis/trac/ticket/106>: "Vary
			header classification"
	Index		Index
	A		A
	age 7		age 7
	Age header 27		Age header 27
	C		C
	cache 5		cache 5
	Cache Directives		Cache Directives
	max-age 32-33		max-age 32-33
	max-stale 32		max-stale 32
	min-fresh 32		min-fresh 32
	must-revalidate 34		must-revalidate 34
	no-cache 29		no-cache 29
	no-store 30		no-store 30
	no-transform 35		no-transform 35
End of changes. 15 change blocks.
	26 lines changed or deleted		35 lines changed or added
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