< draft-nottingham-linked-cache-inv-02.txt		draft-nottingham-linked-cache-inv-03.txt >
	Network Working Group M. Nottingham		Network Working Group M. Nottingham
	Internet-Draft M. Kelly		Internet-Draft M. Kelly
	Intended status: Informational June 1, 2012		Intended status: Informational June 27, 2012
	Expires: December 3, 2012		Expires: December 29, 2012
	Linked Cache Invalidation		Linked Cache Invalidation
	draft-nottingham-linked-cache-inv-02		draft-nottingham-linked-cache-inv-03
	Abstract		Abstract
	This memo defines two new link types that indicate relationships		This memo defines two new link types that indicate relationships
	between resources in terms of cache invalidation, along with a HTTP		between resources in terms of cache invalidation, along with a HTTP
	cache-control extension that takes advantage of those relationships		cache-control extension that takes advantage of those relationships
	to use them to extend response freshness. Collectively, this is		to use them to extend response freshness. Collectively, this is
	referred to as Linked Cache Invalidation (LCI).		referred to as Linked Cache Invalidation (LCI).
	Status of this Memo		Status of this Memo
	skipping to change at page 1, line 34 ¶		skipping to change at page 1, line 34 ¶
	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 December 3, 2012.		This Internet-Draft will expire on December 29, 2012.
	Copyright Notice		Copyright Notice
	Copyright (c) 2012 IETF Trust and the persons identified as the		Copyright (c) 2012 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
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document.		to this document.
	Table of Contents		Table of Contents
	1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3		1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
	1.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . . 3		1.1. Example . . . . . . . . . . . . . . . . . . . . . . . . . . 3
	2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 5		2. Notational Conventions . . . . . . . . . . . . . . . . . . . . 5
	3. The 'invalidates' link relation type . . . . . . . . . . . . . 5		3. The 'invalidates' Link Relation Type . . . . . . . . . . . . . 5
	4. The 'inv-by' link relation type . . . . . . . . . . . . . . . . 5		4. The 'inv-by' Link Relation Type . . . . . . . . . . . . . . . . 5
	5. The 'inv-maxage' response cache-control extension . . . . . . . 6		5. The 'inv-maxage' Response Cache-Control Extension . . . . . . . 6
			5.1. inv-maxage Syntax . . . . . . . . . . . . . . . . . . . . . 6
			5.2. inv-maxage Semantics . . . . . . . . . . . . . . . . . . . 6
	6. Security Considerations . . . . . . . . . . . . . . . . . . . . 7		6. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
	7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7		7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 8
	8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8		8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 8
	8.1. Normative References . . . . . . . . . . . . . . . . . . . 8		8.1. Normative References . . . . . . . . . . . . . . . . . . . 8
	8.2. Informative References . . . . . . . . . . . . . . . . . . 8		8.2. Informative References . . . . . . . . . . . . . . . . . . 8
	Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . . 8		Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . . 8
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
	1. Introduction		1. Introduction
	In normal operation, a HTTP [RFC2616] cache will invalidate a stored		In normal operation, a HTTP [RFC2616] cache will invalidate a stored
	response if an unsafe request (e.g., POST, PUT or DELETE) is made to		response if an unsafe request (e.g., POST, PUT or DELETE) is made to
	skipping to change at page 5, line 31 ¶		skipping to change at page 5, line 31 ¶
	2. Notational Conventions		2. Notational Conventions
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
	document are to be interpreted as described in RFC 2119 [RFC2119].		document are to be interpreted as described in RFC 2119 [RFC2119].
	This document uses the Augmented Backus-Naur Form (ABNF) notation of		This document uses the Augmented Backus-Naur Form (ABNF) notation of
	[RFC2616], and explicitly includes the following rules from it:		[RFC2616], and explicitly includes the following rules from it:
	delta-seconds.		delta-seconds.
	3. The 'invalidates' link relation type		3. The 'invalidates' Link Relation Type
	The 'invalidates' link relation type allows a response that signifies		The 'invalidates' link relation type allows a response that signifies
	a state change on the server to indicate one or more associated URIs		a state change on the server to indicate one or more associated URIs
	whose states have also changed.		whose states have also changed.
	o Relation name: invalidates		o Relation name: invalidates
	o Description: Indicates that when the link context changes, the		o Description: Indicates that when the link context changes, the
	link target also has changed.		link target also has changed.
	o Reference: [this document]		o Reference: [this document]
	o Notes:		o Notes:
	4. The 'inv-by' link relation type		4. The 'inv-by' Link Relation Type
	The 'inv-by' link relation type allows a response to nominate one or		The 'inv-by' link relation type allows a response to nominate one or
	more other resources that affect the state of the resource it's		more other resources that affect the state of the resource it's
	associated with. That is, when one of the nominated resources		associated with. That is, when one of the nominated resources
	changes, it also changes the state of this response's resource.		changes, it also changes the state of this response's resource.
	o Relation name: inv-by		o Relation name: inv-by
	o Description: Indicates that when the link target changes, the		o Description: Indicates that when the link target changes, the
	link's context has also changed.		link's context has also changed.
	o Reference: [this document]		o Reference: [this document]
	o Notes:		o Notes:
	5. The 'inv-maxage' response cache-control extension		5. The 'inv-maxage' Response Cache-Control Extension
	When present, the 'inv-maxage' cache-control extension indicates the		When present, the 'inv-maxage' cache-control extension indicates the
	number of seconds that caches who implement Linked Cache invalidation		number of seconds that caches who implement Linked Cache invalidation
	can consider responses fresh for, provided they are not invalidated.		can consider responses fresh for, provided they are not invalidated.
	"inv-maxage" "=" delta-seconds		5.1. inv-maxage Syntax
			The inv-maxage cache-control extension is parameterised with a
			numeric argument:
			"inv-maxage" "=" ( delta-seconds | ( <"> delta-seconds <"> ) )
			Note that the argument MAY occur in either token or quoted-string
			form.
			If the argument is missing or otherwise does not conform to the BNF
			rule, it is invalid and MUST be ignored by caches.
			If the directive appears more than once in a response, each instance
			is invalid and MUST be ignored by caches.
			5.2. inv-maxage Semantics
	HTTP caches MAY, if they fully implement this specification,		HTTP caches MAY, if they fully implement this specification,
	disregard the HTTP response cache-control directives 'no-cache',		disregard the HTTP response cache-control directives 'no-cache',
	'max-age' and 's-maxage' and use the value of inv-maxage as a		'max-age' and 's-maxage' when a valid 'inv-maxage' cache-control
	replacement for max-age.		directive is present in a response, using its value as a replacement
			for max-age.
	HTTP caches using inv-maxage to calculate freshness MUST invalidate		HTTP caches using inv-maxage to calculate freshness MUST invalidate
	all stored responses whose request-URIs (after normalisation) are the		all stored responses whose request-URIs (after normalisation) are the
	target of a 'invalidates' link relation contained in a successful		target of a 'invalidates' link relation contained in a successful
	response to a state-changing request, provided that they are allowed.		response to a state-changing request, provided that they are allowed.
	HTTP caches using inv-maxage to calculate freshness MUST invalidate		HTTP caches using inv-maxage to calculate freshness MUST invalidate
	all stored responses containing a 'inv-by' link relation whose target		all stored responses containing a 'inv-by' link relation whose target
	is the current request-URI (after normalisation) upon receipt of a		is the current request-URI (after normalisation) upon receipt of a
	successful response to a state-changing request.		successful response to a state-changing request.
	skipping to change at page 7, line 45 ¶		skipping to change at page 8, line 14 ¶
	attacks through invalidation, cache efficiency may still be impaired		attacks through invalidation, cache efficiency may still be impaired
	under certain circumstances (e.g., arranging for one request to		under certain circumstances (e.g., arranging for one request to
	invalidate a large number of responses), leading to a reduction in		invalidate a large number of responses), leading to a reduction in
	service quality.		service quality.
	7. IANA Considerations		7. IANA Considerations
	This document registers two entries in the Link Relation Type		This document registers two entries in the Link Relation Type
	Registry; see Section 3 and Section 4.		Registry; see Section 3 and Section 4.
			It also registers a HTTP Cache Directive, "inv-maxage"; see
			Section 5.
	8. References		8. References
	8.1. Normative References		8.1. Normative References
	[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.
	[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, June 1999.		Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
	[RFC5988] Nottingham, M., "Web Linking", RFC 5988, October 2010.		[RFC5988] Nottingham, M., "Web Linking", RFC 5988, October 2010.
End of changes. 12 change blocks.
	14 lines changed or deleted		37 lines changed or added
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