draft-ietf-httpbis-p4-conditional-11.txt		draft-ietf-httpbis-p4-conditional-latest.txt
	HTTPbis Working Group R. Fielding, Ed.		HTTPbis 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 Alcatel-Lucent		Intended status: Standards Track Alcatel-Lucent
	Expires: February 5, 2011 J. Mogul		Expires: March 6, 2011 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
	August 4, 2010		September 2, 2010
	HTTP/1.1, part 4: Conditional Requests		HTTP/1.1, part 4: Conditional Requests
	draft-ietf-httpbis-p4-conditional-11		draft-ietf-httpbis-p4-conditional-latest
	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 4 of the		information initiative since 1990. This document is Part 4 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 4 defines		"HTTP/1.1" and, taken together, obsoletes RFC 2616. Part 4 defines
	request header fields for indicating conditional requests and the		request header fields for indicating conditional requests and the
	rules for constructing responses to those requests.		rules for constructing responses to those requests.
	Editorial Note (To be removed by RFC Editor)		Editorial Note (To be removed by RFC Editor)
	Discussion of this draft should take place on the HTTPBIS working		Discussion of this draft should take place on the HTTPBIS working
	group mailing list (ietf-http-wg@w3.org). The current issues list is		group mailing list (ietf-http-wg@w3.org). The current issues list is
	at <http://tools.ietf.org/wg/httpbis/trac/report/3> and related		at <http://tools.ietf.org/wg/httpbis/trac/report/3> and related
	documents (including fancy diffs) can be found at		documents (including fancy diffs) can be found at
	<http://tools.ietf.org/wg/httpbis/>.		<http://tools.ietf.org/wg/httpbis/>.
	The changes in this draft are summarized in Appendix C.12.		The changes in this draft are summarized in Appendix C.13.
	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 http://datatracker.ietf.org/drafts/current/.		Drafts is at http://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 February 5, 2011.		This Internet-Draft will expire on March 6, 2011.
	Copyright Notice		Copyright Notice
	Copyright (c) 2010 IETF Trust and the persons identified as the		Copyright (c) 2010 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
	(http://trustee.ietf.org/license-info) in effect on the date of		(http://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 7		skipping to change at page 3, line 7
	modifications of such material outside the IETF Standards Process.		modifications of such material outside the IETF Standards Process.
	Without obtaining an adequate license from the person(s) controlling		Without obtaining an adequate license from the person(s) controlling
	the copyright in such materials, this document may not be modified		the copyright in such materials, this document may not be modified
	outside the IETF Standards Process, and derivative works of it may		outside the IETF Standards Process, and derivative works of it may
	not be created outside the IETF Standards Process, except to format		not be created outside the IETF Standards Process, except to format
	it for publication as an RFC or to translate it into languages other		it for publication as an RFC or to translate it into languages other
	than English.		than English.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
	1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . . 4		1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . . 5
	1.2. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 4		1.2. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 5
	1.2.1. Core Rules . . . . . . . . . . . . . . . . . . . . . . 5		1.2.1. Core Rules . . . . . . . . . . . . . . . . . . . . . . 6
	1.2.2. ABNF Rules defined in other Parts of the		1.2.2. ABNF Rules defined in other Parts of the
	Specification . . . . . . . . . . . . . . . . . . . . 5		Specification . . . . . . . . . . . . . . . . . . . . 6
	2. Entity-Tags . . . . . . . . . . . . . . . . . . . . . . . . . 5		2. Entity-Tags . . . . . . . . . . . . . . . . . . . . . . . . . 6
	2.1. Example: Entity-tags varying on Content-Negotiated		2.1. Example: Entity-tags varying on Content-Negotiated
	Resources . . . . . . . . . . . . . . . . . . . . . . . . 6		Resources . . . . . . . . . . . . . . . . . . . . . . . . 7
	3. Status Code Definitions . . . . . . . . . . . . . . . . . . . 7		3. Status Code Definitions . . . . . . . . . . . . . . . . . . . 8
	3.1. 304 Not Modified . . . . . . . . . . . . . . . . . . . . . 7		3.1. 304 Not Modified . . . . . . . . . . . . . . . . . . . . . 8
	3.2. 412 Precondition Failed . . . . . . . . . . . . . . . . . 7		3.2. 412 Precondition Failed . . . . . . . . . . . . . . . . . 8
	4. Weak and Strong Validators . . . . . . . . . . . . . . . . . . 8		4. Weak and Strong Validators . . . . . . . . . . . . . . . . . . 9
	5. Rules for When to Use Entity-tags and Last-Modified Dates . . 10		5. Rules for When to Use Entity-tags and Last-Modified Dates . . 11
	6. Header Field Definitions . . . . . . . . . . . . . . . . . . . 12		6. Header Field Definitions . . . . . . . . . . . . . . . . . . . 13
	6.1. ETag . . . . . . . . . . . . . . . . . . . . . . . . . . . 12		6.1. ETag . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
	6.2. If-Match . . . . . . . . . . . . . . . . . . . . . . . . . 13		6.2. If-Match . . . . . . . . . . . . . . . . . . . . . . . . . 14
	6.3. If-Modified-Since . . . . . . . . . . . . . . . . . . . . 14		6.3. If-Modified-Since . . . . . . . . . . . . . . . . . . . . 15
	6.4. If-None-Match . . . . . . . . . . . . . . . . . . . . . . 16		6.4. If-None-Match . . . . . . . . . . . . . . . . . . . . . . 17
	6.5. If-Unmodified-Since . . . . . . . . . . . . . . . . . . . 17		6.5. If-Unmodified-Since . . . . . . . . . . . . . . . . . . . 18
	6.6. Last-Modified . . . . . . . . . . . . . . . . . . . . . . 18		6.6. Last-Modified . . . . . . . . . . . . . . . . . . . . . . 19
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 18		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 19
	7.1. Status Code Registration . . . . . . . . . . . . . . . . . 19		7.1. Status Code Registration . . . . . . . . . . . . . . . . . 20
	7.2. Header Field Registration . . . . . . . . . . . . . . . . 19		7.2. Header Field Registration . . . . . . . . . . . . . . . . 20
	8. Security Considerations . . . . . . . . . . . . . . . . . . . 19		8. Security Considerations . . . . . . . . . . . . . . . . . . . 20
	9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 19		9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 20
	10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 19		10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 20
	10.1. Normative References . . . . . . . . . . . . . . . . . . . 19		10.1. Normative References . . . . . . . . . . . . . . . . . . . 20
	10.2. Informative References . . . . . . . . . . . . . . . . . . 20		10.2. Informative References . . . . . . . . . . . . . . . . . . 21
	Appendix A. Changes from RFC 2616 . . . . . . . . . . . . . . . . 20		Appendix A. Changes from RFC 2616 . . . . . . . . . . . . . . . . 21
	Appendix B. Collected ABNF . . . . . . . . . . . . . . . . . . . 21		Appendix B. Collected ABNF . . . . . . . . . . . . . . . . . . . 22
	Appendix C. Change Log (to be removed by RFC Editor before		Appendix C. Change Log (to be removed by RFC Editor before
	publication) . . . . . . . . . . . . . . . . . . . . 21		publication) . . . . . . . . . . . . . . . . . . . . 22
	C.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 21		C.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 22
	C.2. Since draft-ietf-httpbis-p4-conditional-00 . . . . . . . . 22		C.2. Since draft-ietf-httpbis-p4-conditional-00 . . . . . . . . 23
	C.3. Since draft-ietf-httpbis-p4-conditional-01 . . . . . . . . 22		C.3. Since draft-ietf-httpbis-p4-conditional-01 . . . . . . . . 23
	C.4. Since draft-ietf-httpbis-p4-conditional-02 . . . . . . . . 22		C.4. Since draft-ietf-httpbis-p4-conditional-02 . . . . . . . . 23
	C.5. Since draft-ietf-httpbis-p4-conditional-03 . . . . . . . . 22		C.5. Since draft-ietf-httpbis-p4-conditional-03 . . . . . . . . 23
	C.6. Since draft-ietf-httpbis-p4-conditional-04 . . . . . . . . 23		C.6. Since draft-ietf-httpbis-p4-conditional-04 . . . . . . . . 24
	C.7. Since draft-ietf-httpbis-p4-conditional-05 . . . . . . . . 23		C.7. Since draft-ietf-httpbis-p4-conditional-05 . . . . . . . . 24
	C.8. Since draft-ietf-httpbis-p4-conditional-06 . . . . . . . . 23		C.8. Since draft-ietf-httpbis-p4-conditional-06 . . . . . . . . 24
	C.9. Since draft-ietf-httpbis-p4-conditional-07 . . . . . . . . 23		C.9. Since draft-ietf-httpbis-p4-conditional-07 . . . . . . . . 24
	C.10. Since draft-ietf-httpbis-p4-conditional-08 . . . . . . . . 23		C.10. Since draft-ietf-httpbis-p4-conditional-08 . . . . . . . . 24
	C.11. Since draft-ietf-httpbis-p4-conditional-09 . . . . . . . . 23		C.11. Since draft-ietf-httpbis-p4-conditional-09 . . . . . . . . 24
	C.12. Since draft-ietf-httpbis-p4-conditional-10 . . . . . . . . 24		C.12. Since draft-ietf-httpbis-p4-conditional-10 . . . . . . . . 25
	Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24		C.13. Since draft-ietf-httpbis-p4-conditional-11 . . . . . . . . 25
			Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
	1. Introduction		1. Introduction
	This document defines HTTP/1.1 response metadata for indicating		This document defines HTTP/1.1 response metadata for indicating
	potential changes to payload content, including modification time		potential changes to payload content, including modification time
	stamps and opaque entity-tags, and the HTTP conditional request		stamps and opaque entity-tags, and the HTTP conditional request
	mechanisms that allow preconditions to be placed on a request method.		mechanisms that allow preconditions to be placed on a request method.
	Conditional GET requests allow for efficient cache updates. Other		Conditional GET requests allow for efficient cache updates. Other
	conditional request methods are used to protect against overwriting		conditional request methods are used to protect against overwriting
	or misunderstanding the state of a resource that has been changed		or misunderstanding the state of a resource that has been changed
	unbeknownst to the requesting client.		unbeknownst to the requesting client.
	This document is currently disorganized in order to minimize the		This document is currently disorganized in order to minimize the
	changes between drafts and enable reviewers to see the smaller errata		changes between drafts and enable reviewers to see the smaller errata
	changes. The next draft will reorganize the sections to better		changes. A future draft will reorganize the sections to better
	reflect the content. In particular, the sections on resource		reflect the content. In particular, the sections on resource
	metadata will be discussed first and then followed by each		metadata will be discussed first and then followed by each
	conditional request-header, concluding with a definition of		conditional request-header, concluding with a definition of
	precedence and the expectation of ordering strong validator checks		precedence and the expectation of ordering strong validator checks
	before weak validator checks. It is likely that more content from		before weak validator checks. It is likely that more content from
	[Part6] will migrate to this part, where appropriate. The current		[Part6] will migrate to this part, where appropriate. The current
	mess reflects how widely dispersed these topics and associated		mess reflects how widely dispersed these topics and associated
	requirements had become in [RFC2616].		requirements had become in [RFC2616].
	1.1. Requirements		1.1. Requirements
	skipping to change at page 19, line 51		skipping to change at page 20, line 51
	9. Acknowledgments		9. Acknowledgments
	10. References		10. References
	10.1. Normative References		10.1. Normative References
	[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-11		and Message Parsing",
	(work in progress), August 2010.		draft-ietf-httpbis-p1-messaging-latest (work in progress),
			September 2010.
	[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-11		and Content Negotiation",
	(work in progress), August 2010.		draft-ietf-httpbis-p3-payload-latest (work in progress),
			September 2010.
	[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-11 (work		Partial Responses", draft-ietf-httpbis-p5-range-latest
	in progress), August 2010.		(work in progress), September 2010.
	[Part6] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,		[Part6] 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.,
	Nottingham, M., Ed., and J. Reschke, Ed., "HTTP/1.1, part		Nottingham, M., Ed., and J. Reschke, Ed., "HTTP/1.1, part
	6: Caching", draft-ietf-httpbis-p6-cache-11 (work in		6: Caching", draft-ietf-httpbis-p6-cache-latest (work in
	progress), August 2010.		progress), September 2010.
	[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.
	[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, January 2008.		Specifications: ABNF", STD 68, RFC 5234, January 2008.
	10.2. Informative References		10.2. Informative References
	[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,		[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
	skipping to change at page 24, line 18		skipping to change at page 25, line 18
	o <http://tools.ietf.org/wg/httpbis/trac/ticket/69>: "Clarify		o <http://tools.ietf.org/wg/httpbis/trac/ticket/69>: "Clarify
	'Requested Variant'"		'Requested Variant'"
	o <http://tools.ietf.org/wg/httpbis/trac/ticket/109>: "Clarify		o <http://tools.ietf.org/wg/httpbis/trac/ticket/109>: "Clarify
	entity / representation / variant terminology"		entity / representation / variant terminology"
	o <http://tools.ietf.org/wg/httpbis/trac/ticket/220>: "consider		o <http://tools.ietf.org/wg/httpbis/trac/ticket/220>: "consider
	removing the 'changes from 2068' sections"		removing the 'changes from 2068' sections"
			C.13. Since draft-ietf-httpbis-p4-conditional-11
			None yet.
	Index		Index
	3		3
	304 Not Modified (status code) 7		304 Not Modified (status code) 8
	4		4
	412 Precondition Failed (status code) 7		412 Precondition Failed (status code) 8
	E		E
	ETag header 12		ETag header 13
	G		G
	Grammar		Grammar
	entity-tag 5		entity-tag 6
	ETag 12		ETag 13
	ETag-v 12		ETag-v 13
	If-Match 13		If-Match 14
	If-Match-v 13		If-Match-v 14
	If-Modified-Since 14		If-Modified-Since 15
	If-Modified-Since-v 14		If-Modified-Since-v 15
	If-None-Match 16		If-None-Match 17
	If-None-Match-v 16		If-None-Match-v 17
	If-Unmodified-Since 17		If-Unmodified-Since 18
	If-Unmodified-Since-v 17		If-Unmodified-Since-v 18
	Last-Modified 18		Last-Modified 19
	Last-Modified-v 18		Last-Modified-v 19
	opaque-tag 5		opaque-tag 6
	weak 5		weak 6
	H		H
	Headers		Headers
	ETag 12		ETag 13
	If-Match 13		If-Match 14
	If-Modified-Since 14		If-Modified-Since 15
	If-None-Match 16		If-None-Match 17
	If-Unmodified-Since 17		If-Unmodified-Since 18
	Last-Modified 18		Last-Modified 19
	I		I
	If-Match header 13		If-Match header 14
	If-Modified-Since header 14		If-Modified-Since header 15
	If-None-Match header 16		If-None-Match header 17
	If-Unmodified-Since header 17		If-Unmodified-Since header 18
	L		L
	Last-Modified header 18		Last-Modified header 19
	S		S
	Status Codes		Status Codes
	304 Not Modified 7		304 Not Modified 8
	412 Precondition Failed 7		412 Precondition Failed 8
	Authors' Addresses		Authors' Addresses
	Roy T. Fielding (editor)		Roy T. Fielding (editor)
	Day Software		Day Software
	23 Corporate Plaza DR, Suite 280		23 Corporate Plaza DR, Suite 280
	Newport Beach, CA 92660		Newport Beach, CA 92660
	USA		USA
	Phone: +1-949-706-5300		Phone: +1-949-706-5300
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