draft-ietf-httpbis-p6-cache-17.txt | draft-ietf-httpbis-p6-cache-18.txt | |||
---|---|---|---|---|
HTTPbis Working Group R. Fielding, Ed. | HTTPbis Working Group R. Fielding, Ed. | |||
Internet-Draft Adobe | Internet-Draft Adobe | |||
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: May 3, 2012 J. Mogul | Expires: July 7, 2012 J. Mogul | |||
HP | HP | |||
H. Frystyk | H. Frystyk | |||
Microsoft | Microsoft | |||
L. Masinter | L. Masinter | |||
Adobe | Adobe | |||
P. Leach | P. Leach | |||
Microsoft | Microsoft | |||
T. Berners-Lee | T. Berners-Lee | |||
W3C/MIT | W3C/MIT | |||
Y. Lafon, Ed. | Y. Lafon, Ed. | |||
W3C | W3C | |||
M. Nottingham, Ed. | M. Nottingham, Ed. | |||
Rackspace | Rackspace | |||
J. Reschke, Ed. | J. Reschke, Ed. | |||
greenbytes | greenbytes | |||
October 31, 2011 | January 4, 2012 | |||
HTTP/1.1, part 6: Caching | HTTP/1.1, part 6: Caching | |||
draft-ietf-httpbis-p6-cache-17 | draft-ietf-httpbis-p6-cache-18 | |||
Abstract | Abstract | |||
The Hypertext Transfer Protocol (HTTP) is an application-level | The Hypertext Transfer Protocol (HTTP) is an application-level | |||
protocol for distributed, collaborative, hypertext information | protocol for distributed, collaborative, hypertext 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. | "HTTP/1.1" and, taken together, obsoletes RFC 2616. | |||
skipping to change at page 2, line 6 | skipping to change at page 2, line 6 | |||
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), which is archived at | group mailing list (ietf-http-wg@w3.org), which is archived at | |||
<http://lists.w3.org/Archives/Public/ietf-http-wg/>. | <http://lists.w3.org/Archives/Public/ietf-http-wg/>. | |||
The current issues list is at | The current issues list is at | |||
<http://tools.ietf.org/wg/httpbis/trac/report/3> and related | <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.18. | The changes in this draft are summarized in Appendix C.19. | |||
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 May 3, 2012. | This Internet-Draft will expire on July 7, 2012. | |||
Copyright Notice | Copyright Notice | |||
Copyright (c) 2011 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. Code Components extracted from this document must | to this document. Code Components extracted from this document must | |||
include Simplified BSD License text as described in Section 4.e of | include Simplified BSD License text as described in Section 4.e of | |||
the Trust Legal Provisions and are provided without warranty as | the Trust Legal Provisions and are provided without warranty as | |||
skipping to change at page 3, line 19 | skipping to change at page 3, line 19 | |||
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 | 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 | |||
1.3. Conformance and Error Handling . . . . . . . . . . . . . . 7 | 1.3. Conformance and Error Handling . . . . . . . . . . . . . . 7 | |||
1.4. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 7 | 1.4. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 7 | |||
1.4.1. Core Rules . . . . . . . . . . . . . . . . . . . . . . 8 | 1.4.1. Core Rules . . . . . . . . . . . . . . . . . . . . . . 8 | |||
1.4.2. ABNF Rules defined in other Parts of the | 1.4.2. ABNF Rules defined in other Parts of the | |||
Specification . . . . . . . . . . . . . . . . . . . . 8 | Specification . . . . . . . . . . . . . . . . . . . . 8 | |||
1.5. Delta Seconds . . . . . . . . . . . . . . . . . . . . . . 8 | 1.5. Delta Seconds . . . . . . . . . . . . . . . . . . . . . . 8 | |||
2. Cache Operation . . . . . . . . . . . . . . . . . . . . . . . 8 | 2. Cache Operation . . . . . . . . . . . . . . . . . . . . . . . 8 | |||
2.1. Response Cacheability . . . . . . . . . . . . . . . . . . 9 | 2.1. Response Cacheability . . . . . . . . . . . . . . . . . . 9 | |||
2.2. Constructing Responses from Caches . . . . . . . . . . . . 10 | 2.2. Constructing Responses from Caches . . . . . . . . . . . . 10 | |||
2.3. Freshness Model . . . . . . . . . . . . . . . . . . . . . 11 | 2.3. Freshness Model . . . . . . . . . . . . . . . . . . . . . 12 | |||
2.3.1. Calculating Freshness Lifetime . . . . . . . . . . . . 12 | 2.3.1. Calculating Freshness Lifetime . . . . . . . . . . . . 13 | |||
2.3.2. Calculating Age . . . . . . . . . . . . . . . . . . . 13 | 2.3.2. Calculating Age . . . . . . . . . . . . . . . . . . . 14 | |||
2.3.3. Serving Stale Responses . . . . . . . . . . . . . . . 15 | 2.3.3. Serving Stale Responses . . . . . . . . . . . . . . . 16 | |||
2.4. Validation Model . . . . . . . . . . . . . . . . . . . . . 16 | 2.4. Validation Model . . . . . . . . . . . . . . . . . . . . . 16 | |||
2.4.1. Freshening Responses . . . . . . . . . . . . . . . . . 17 | 2.4.1. Freshening Responses . . . . . . . . . . . . . . . . . 17 | |||
2.5. Request Methods that Invalidate . . . . . . . . . . . . . 18 | 2.5. Request Methods that Invalidate . . . . . . . . . . . . . 18 | |||
2.6. Shared Caching of Authenticated Responses . . . . . . . . 18 | 2.6. Shared Caching of Authenticated Responses . . . . . . . . 18 | |||
2.7. Caching Negotiated Responses . . . . . . . . . . . . . . . 19 | 2.7. Caching Negotiated Responses . . . . . . . . . . . . . . . 19 | |||
2.8. Combining Partial Content . . . . . . . . . . . . . . . . 20 | 2.8. Combining Partial Content . . . . . . . . . . . . . . . . 20 | |||
3. Header Field Definitions . . . . . . . . . . . . . . . . . . . 20 | 3. Header Field Definitions . . . . . . . . . . . . . . . . . . . 20 | |||
3.1. Age . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 | 3.1. Age . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 | |||
3.2. Cache-Control . . . . . . . . . . . . . . . . . . . . . . 21 | 3.2. Cache-Control . . . . . . . . . . . . . . . . . . . . . . 21 | |||
3.2.1. Request Cache-Control Directives . . . . . . . . . . . 21 | 3.2.1. Request Cache-Control Directives . . . . . . . . . . . 21 | |||
3.2.2. Response Cache-Control Directives . . . . . . . . . . 23 | 3.2.2. Response Cache-Control Directives . . . . . . . . . . 23 | |||
3.2.3. Cache Control Extensions . . . . . . . . . . . . . . . 26 | 3.2.3. Cache Control Extensions . . . . . . . . . . . . . . . 26 | |||
3.3. Expires . . . . . . . . . . . . . . . . . . . . . . . . . 27 | 3.3. Expires . . . . . . . . . . . . . . . . . . . . . . . . . 27 | |||
3.4. Pragma . . . . . . . . . . . . . . . . . . . . . . . . . . 28 | 3.4. Pragma . . . . . . . . . . . . . . . . . . . . . . . . . . 28 | |||
3.5. Vary . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 | 3.5. Vary . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 | |||
3.6. Warning . . . . . . . . . . . . . . . . . . . . . . . . . 29 | 3.6. Warning . . . . . . . . . . . . . . . . . . . . . . . . . 29 | |||
4. History Lists . . . . . . . . . . . . . . . . . . . . . . . . 32 | 3.6.1. 110 Response is Stale . . . . . . . . . . . . . . . . 31 | |||
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 32 | 3.6.2. 111 Revalidation Failed . . . . . . . . . . . . . . . 31 | |||
5.1. Cache Directive Registry . . . . . . . . . . . . . . . . . 32 | 3.6.3. 112 Disconnected Operation . . . . . . . . . . . . . . 31 | |||
5.2. Header Field Registration . . . . . . . . . . . . . . . . 33 | 3.6.4. 113 Heuristic Expiration . . . . . . . . . . . . . . . 31 | |||
6. Security Considerations . . . . . . . . . . . . . . . . . . . 33 | 3.6.5. 199 Miscellaneous Warning . . . . . . . . . . . . . . 31 | |||
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 33 | 3.6.6. 214 Transformation Applied . . . . . . . . . . . . . . 31 | |||
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 33 | 3.6.7. 299 Miscellaneous Persistent Warning . . . . . . . . . 31 | |||
8.1. Normative References . . . . . . . . . . . . . . . . . . . 33 | 3.6.8. Warn Code Extensions . . . . . . . . . . . . . . . . . 32 | |||
8.2. Informative References . . . . . . . . . . . . . . . . . . 34 | 3.7. History Lists . . . . . . . . . . . . . . . . . . . . . . 32 | |||
3.8. IANA Considerations . . . . . . . . . . . . . . . . . . . 32 | ||||
3.8.1. Cache Directive Registry . . . . . . . . . . . . . . . 32 | ||||
3.8.2. Warn Code Registry . . . . . . . . . . . . . . . . . . 33 | ||||
3.9. Header Field Registration . . . . . . . . . . . . . . . . 33 | ||||
4. Security Considerations . . . . . . . . . . . . . . . . . . . 34 | ||||
5. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 34 | ||||
6. References . . . . . . . . . . . . . . . . . . . . . . . . . . 34 | ||||
6.1. Normative References . . . . . . . . . . . . . . . . . . . 34 | ||||
6.2. Informative References . . . . . . . . . . . . . . . . . . 35 | ||||
Appendix A. Changes from RFC 2616 . . . . . . . . . . . . . . . . 35 | Appendix A. Changes from RFC 2616 . . . . . . . . . . . . . . . . 35 | |||
Appendix B. Collected ABNF . . . . . . . . . . . . . . . . . . . 35 | Appendix B. Collected ABNF . . . . . . . . . . . . . . . . . . . 36 | |||
Appendix C. Change Log (to be removed by RFC Editor before | Appendix C. Change Log (to be removed by RFC Editor before | |||
publication) . . . . . . . . . . . . . . . . . . . . 36 | publication) . . . . . . . . . . . . . . . . . . . . 37 | |||
C.1. Since RFC 2616 . . . . . . . . . . . . . . . . . . . . . . 36 | C.1. Since RFC 2616 . . . . . . . . . . . . . . . . . . . . . . 37 | |||
C.2. Since draft-ietf-httpbis-p6-cache-00 . . . . . . . . . . . 37 | C.2. Since draft-ietf-httpbis-p6-cache-00 . . . . . . . . . . . 37 | |||
C.3. Since draft-ietf-httpbis-p6-cache-01 . . . . . . . . . . . 37 | C.3. Since draft-ietf-httpbis-p6-cache-01 . . . . . . . . . . . 38 | |||
C.4. Since draft-ietf-httpbis-p6-cache-02 . . . . . . . . . . . 38 | C.4. Since draft-ietf-httpbis-p6-cache-02 . . . . . . . . . . . 38 | |||
C.5. Since draft-ietf-httpbis-p6-cache-03 . . . . . . . . . . . 38 | C.5. Since draft-ietf-httpbis-p6-cache-03 . . . . . . . . . . . 39 | |||
C.6. Since draft-ietf-httpbis-p6-cache-04 . . . . . . . . . . . 38 | C.6. Since draft-ietf-httpbis-p6-cache-04 . . . . . . . . . . . 39 | |||
C.7. Since draft-ietf-httpbis-p6-cache-05 . . . . . . . . . . . 38 | C.7. Since draft-ietf-httpbis-p6-cache-05 . . . . . . . . . . . 39 | |||
C.8. Since draft-ietf-httpbis-p6-cache-06 . . . . . . . . . . . 39 | C.8. Since draft-ietf-httpbis-p6-cache-06 . . . . . . . . . . . 40 | |||
C.9. Since draft-ietf-httpbis-p6-cache-07 . . . . . . . . . . . 39 | C.9. Since draft-ietf-httpbis-p6-cache-07 . . . . . . . . . . . 40 | |||
C.10. Since draft-ietf-httpbis-p6-cache-08 . . . . . . . . . . . 39 | C.10. Since draft-ietf-httpbis-p6-cache-08 . . . . . . . . . . . 40 | |||
C.11. Since draft-ietf-httpbis-p6-cache-09 . . . . . . . . . . . 40 | C.11. Since draft-ietf-httpbis-p6-cache-09 . . . . . . . . . . . 41 | |||
C.12. Since draft-ietf-httpbis-p6-cache-10 . . . . . . . . . . . 40 | C.12. Since draft-ietf-httpbis-p6-cache-10 . . . . . . . . . . . 41 | |||
C.13. Since draft-ietf-httpbis-p6-cache-11 . . . . . . . . . . . 41 | C.13. Since draft-ietf-httpbis-p6-cache-11 . . . . . . . . . . . 41 | |||
C.14. Since draft-ietf-httpbis-p6-cache-12 . . . . . . . . . . . 41 | C.14. Since draft-ietf-httpbis-p6-cache-12 . . . . . . . . . . . 42 | |||
C.15. Since draft-ietf-httpbis-p6-cache-13 . . . . . . . . . . . 41 | C.15. Since draft-ietf-httpbis-p6-cache-13 . . . . . . . . . . . 42 | |||
C.16. Since draft-ietf-httpbis-p6-cache-14 . . . . . . . . . . . 41 | C.16. Since draft-ietf-httpbis-p6-cache-14 . . . . . . . . . . . 42 | |||
C.17. Since draft-ietf-httpbis-p6-cache-15 . . . . . . . . . . . 42 | C.17. Since draft-ietf-httpbis-p6-cache-15 . . . . . . . . . . . 42 | |||
C.18. Since draft-ietf-httpbis-p6-cache-16 . . . . . . . . . . . 42 | C.18. Since draft-ietf-httpbis-p6-cache-16 . . . . . . . . . . . 43 | |||
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 | C.19. Since draft-ietf-httpbis-p6-cache-17 . . . . . . . . . . . 43 | |||
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 | ||||
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. This | performance can be improved by the use of response caches. This | |||
document defines aspects of HTTP/1.1 related to caching and reusing | document defines aspects of HTTP/1.1 related to caching and reusing | |||
response messages. | response messages. | |||
1.1. Purpose | 1.1. Purpose | |||
skipping to change at page 11, line 11 | skipping to change at page 11, line 11 | |||
o The presented effective request URI (Section 4.3 of [Part1]) and | o The presented effective request URI (Section 4.3 of [Part1]) and | |||
that of the stored response match, and | that of the stored response match, and | |||
o the request method associated with the stored response allows it | o the request method associated with the stored response allows it | |||
to be used for the presented request, and | to be used for the presented request, and | |||
o selecting header fields nominated by the stored response (if any) | o selecting header fields nominated by the stored response (if any) | |||
match those presented (see Section 2.7), and | match those presented (see Section 2.7), and | |||
o the presented request and stored response are free from directives | o the presented request does not contain the no-cache pragma | |||
that would prevent its use (see Section 3.2 and Section 3.4), and | (Section 3.4), nor the no-cache cache directive (Section 3.2.1), | |||
unless the stored response is successfully validated | ||||
(Section 2.4), and | ||||
o the stored response does not contain the no-cache cache directive | ||||
(Section 3.2.2), unless it is successfully validated | ||||
(Section 2.4), and | ||||
o the stored response is either: | o the stored response is either: | |||
* fresh (see Section 2.3), or | * fresh (see Section 2.3), or | |||
* allowed to be served stale (see Section 2.3.3), or | * allowed to be served stale (see Section 2.3.3), or | |||
* successfully validated (see Section 2.4). | * successfully validated (see Section 2.4). | |||
Note that any of the requirements listed above can be overridden by a | Note that any of the requirements listed above can be overridden by a | |||
skipping to change at page 12, line 34 | skipping to change at page 12, line 40 | |||
expiration time. This specification does not provide specific | expiration time. This specification does not provide specific | |||
algorithms, but does impose worst-case constraints on their results. | algorithms, but does impose worst-case constraints on their results. | |||
The calculation to determine if a response is fresh is: | The calculation to determine if a response is fresh is: | |||
response_is_fresh = (freshness_lifetime > current_age) | response_is_fresh = (freshness_lifetime > current_age) | |||
The freshness_lifetime is defined in Section 2.3.1; the current_age | The freshness_lifetime is defined in Section 2.3.1; the current_age | |||
is defined in Section 2.3.2. | is defined in Section 2.3.2. | |||
Additionally, clients might need to influence freshness calculation. | Additionally, clients can influence freshness calculation -- either | |||
They can do this using several request cache directives, with the | constraining it relaxing it -- by using the max-age and min-fresh | |||
effect of either increasing or loosening constraints on freshness. | request cache directives. See Section 3.2.1 for details. | |||
See Section 3.2.1. | ||||
Note that freshness applies only to cache operation; it cannot be | Note that freshness applies only to cache operation; it cannot be | |||
used to force a user agent to refresh its display or reload a | used to force a user agent to refresh its display or reload a | |||
resource. See Section 4 for an explanation of the difference between | resource. See Section 3.7 for an explanation of the difference | |||
caches and history mechanisms. | between caches and history mechanisms. | |||
2.3.1. Calculating Freshness Lifetime | 2.3.1. Calculating Freshness Lifetime | |||
A cache can calculate the freshness lifetime (denoted as | A cache can calculate the freshness lifetime (denoted as | |||
freshness_lifetime) of a response by using the first match of: | freshness_lifetime) of a response by using the first match of: | |||
o If the cache is shared and the s-maxage response cache directive | o If the cache is shared and the s-maxage response cache directive | |||
(Section 3.2.2) is present, use its value, or | (Section 3.2.2) is present, use its value, or | |||
o If the max-age response cache directive (Section 3.2.2) is | o If the max-age response cache directive (Section 3.2.2) is | |||
skipping to change at page 15, line 10 | skipping to change at page 15, line 20 | |||
2. the "corrected_age_value", if all of the caches along the | 2. the "corrected_age_value", if all of the caches along the | |||
response path implement HTTP/1.1. A cache MUST interpret this | response path implement HTTP/1.1. A cache MUST interpret this | |||
value relative to the time the request was initiated, not the | value relative to the time the request was initiated, not the | |||
time that the response was received. | time that the response was received. | |||
apparent_age = max(0, response_time - date_value); | apparent_age = max(0, response_time - date_value); | |||
response_delay = response_time - request_time; | response_delay = response_time - request_time; | |||
corrected_age_value = age_value + response_delay; | corrected_age_value = age_value + response_delay; | |||
These are combined as | These SHOULD be combined as | |||
corrected_initial_age = max(apparent_age, corrected_age_value); | corrected_initial_age = max(apparent_age, corrected_age_value); | |||
unless the cache is confident in the value of the Age header (e.g., | ||||
because there are no HTTP/1.0 hops in the Via header), in which case | ||||
the corrected_age_value MAY be used as the corrected_initial_age. | ||||
The current_age of a stored response can then be calculated by adding | The current_age of a stored response can then be calculated by adding | |||
the amount of time (in seconds) since the stored response was last | the amount of time (in seconds) since the stored response was last | |||
validated by the origin server to the corrected_initial_age. | validated by the origin server to the corrected_initial_age. | |||
resident_time = now - response_time; | resident_time = now - response_time; | |||
current_age = corrected_initial_age + resident_time; | current_age = corrected_initial_age + resident_time; | |||
Additionally, to avoid common problems in date parsing: | Additionally, to avoid common problems in date parsing: | |||
o HTTP/1.1 clients and caches SHOULD assume that an RFC-850 date | o HTTP/1.1 clients and caches SHOULD assume that an RFC-850 date | |||
skipping to change at page 31, line 12 | skipping to change at page 31, line 12 | |||
warn-date, and that warn-date is different from the Date value in the | warn-date, and that warn-date is different from the Date value in the | |||
response, then that warning-value MUST be deleted from the message | response, then that warning-value MUST be deleted from the message | |||
before storing, forwarding, or using it. (preventing the consequences | before storing, forwarding, or using it. (preventing the consequences | |||
of naive caching of Warning header fields.) If all of the warning- | of naive caching of Warning header fields.) If all of the warning- | |||
values are deleted for this reason, the Warning header field MUST be | values are deleted for this reason, the Warning header field MUST be | |||
deleted as well. | deleted as well. | |||
The following warn-codes are defined by this specification, each with | The following warn-codes are defined by this specification, each with | |||
a recommended warn-text in English, and a description of its meaning. | a recommended warn-text in English, and a description of its meaning. | |||
110 Response is stale | 3.6.1. 110 Response is Stale | |||
A cache SHOULD include this whenever the returned response is | A cache SHOULD include this whenever the returned response is stale. | |||
stale. | ||||
111 Revalidation failed | 3.6.2. 111 Revalidation Failed | |||
A cache SHOULD include this when returning a stale response | A cache SHOULD include this when returning a stale response because | |||
because an attempt to validate the response failed, due to an | an attempt to validate the response failed, due to an inability to | |||
inability to reach the server. | reach the server. | |||
112 Disconnected operation | 3.6.3. 112 Disconnected Operation | |||
A cache SHOULD include this if it is intentionally disconnected | A cache SHOULD include this if it is intentionally disconnected from | |||
from the rest of the network for a period of time. | the rest of the network for a period of time. | |||
113 Heuristic expiration | 3.6.4. 113 Heuristic Expiration | |||
A cache SHOULD include this if it heuristically chose a freshness | A cache SHOULD include this if it heuristically chose a freshness | |||
lifetime greater than 24 hours and the response's age is greater | lifetime greater than 24 hours and the response's age is greater than | |||
than 24 hours. | 24 hours. | |||
199 Miscellaneous warning | 3.6.5. 199 Miscellaneous Warning | |||
The warning text can include arbitrary information to be presented | The warning text can include arbitrary information to be presented to | |||
to a human user, or logged. A system receiving this warning MUST | a human user, or logged. A system receiving this warning MUST NOT | |||
NOT take any automated action, besides presenting the warning to | take any automated action, besides presenting the warning to the | |||
the user. | user. | |||
214 Transformation applied | 3.6.6. 214 Transformation Applied | |||
MUST be added by a proxy if it applies any transformation to the | MUST be added by a proxy if it applies any transformation to the | |||
representation, such as changing the content-coding, media-type, | representation, such as changing the content-coding, media-type, or | |||
or modifying the representation data, unless this Warning code | modifying the representation data, unless this Warning code already | |||
already appears in the response. | appears in the response. | |||
299 Miscellaneous persistent warning | 3.6.7. 299 Miscellaneous Persistent Warning | |||
The warning text can include arbitrary information to be presented | The warning text can include arbitrary information to be presented to | |||
to a human user, or logged. A system receiving this warning MUST | a human user, or logged. A system receiving this warning MUST NOT | |||
NOT take any automated action. | take any automated action. | |||
4. History Lists | 3.6.8. Warn Code Extensions | |||
The HTTP Warn Code Registry defines the name space for warn codes. | ||||
A registration MUST include the following fields: | ||||
o Warn Code (3 digits) | ||||
o Short Description | ||||
o Pointer to specification text | ||||
Values to be added to this name space are subject to IETF review | ||||
([RFC5226], Section 4.1). | ||||
The registry itself is maintained at | ||||
<http://www.iana.org/assignments/http-warn-codes>. | ||||
3.7. 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 2.3) does not necessarily apply to | The freshness model (Section 2.3) does not necessarily apply to | |||
history mechanisms. I.e., a history mechanism can display a previous | history mechanisms. I.e., a history mechanism can display a previous | |||
representation even if it has expired. | representation even if it has expired. | |||
This does not prohibit the history mechanism from telling the user | This does not prohibit the history mechanism from telling the user | |||
that a view might be stale, or from honoring cache directives (e.g., | that a view might be stale, or from honoring cache directives (e.g., | |||
Cache-Control: no-store). | Cache-Control: no-store). | |||
5. IANA Considerations | 3.8. IANA Considerations | |||
5.1. Cache Directive Registry | 3.8.1. Cache Directive Registry | |||
The registration procedure for HTTP Cache Directives is defined by | The registration procedure for HTTP Cache Directives is defined by | |||
Section 3.2.3 of this document. | Section 3.2.3 of this document. | |||
The HTTP Cache Directive Registry shall be created at | The HTTP Cache Directive Registry shall be created at | |||
<http://www.iana.org/assignments/http-cache-directives> and be | <http://www.iana.org/assignments/http-cache-directives> and be | |||
populated with the registrations below: | populated with the registrations below: | |||
+------------------------+------------------------------+ | +------------------------+------------------------------+ | |||
| Cache Directive | Reference | | | Cache Directive | Reference | | |||
skipping to change at page 33, line 5 | skipping to change at page 33, line 24 | |||
| no-transform | Section 3.2.1, Section 3.2.2 | | | no-transform | Section 3.2.1, Section 3.2.2 | | |||
| only-if-cached | Section 3.2.1 | | | only-if-cached | Section 3.2.1 | | |||
| private | Section 3.2.2 | | | private | Section 3.2.2 | | |||
| proxy-revalidate | Section 3.2.2 | | | proxy-revalidate | Section 3.2.2 | | |||
| public | Section 3.2.2 | | | public | Section 3.2.2 | | |||
| s-maxage | Section 3.2.2 | | | s-maxage | Section 3.2.2 | | |||
| stale-if-error | [RFC5861], Section 4 | | | stale-if-error | [RFC5861], Section 4 | | |||
| stale-while-revalidate | [RFC5861], Section 3 | | | stale-while-revalidate | [RFC5861], Section 3 | | |||
+------------------------+------------------------------+ | +------------------------+------------------------------+ | |||
5.2. Header Field Registration | 3.8.2. Warn Code Registry | |||
The registration procedure for HTTP Warn Codes is defined by | ||||
Section 3.6.8 of this document. | ||||
The HTTP Warn Code Registry shall be created at | ||||
<http://www.iana.org/assignments/http-cache-directives> and be | ||||
populated with the registrations below: | ||||
+-----------+----------------------------------+---------------+ | ||||
| Warn Code | Short Description | Reference | | ||||
+-----------+----------------------------------+---------------+ | ||||
| 110 | Response is Stale | Section 3.6.1 | | ||||
| 111 | Revalidation Failed | Section 3.6.2 | | ||||
| 112 | Disconnected Operation | Section 3.6.3 | | ||||
| 113 | Heuristic Expiration | Section 3.6.4 | | ||||
| 199 | Miscellaneous Warning | Section 3.6.5 | | ||||
| 214 | Transformation Applied | Section 3.6.6 | | ||||
| 299 | Miscellaneous Persistent Warning | Section 3.6.7 | | ||||
+-----------+----------------------------------+---------------+ | ||||
3.9. Header Field Registration | ||||
The Message Header Field Registry located at <http://www.iana.org/ | The Message Header Field Registry located at <http://www.iana.org/ | |||
assignments/message-headers/message-header-index.html> shall be | assignments/message-headers/message-header-index.html> shall be | |||
updated with the permanent registrations below (see [RFC3864]): | updated with the permanent registrations below (see [RFC3864]): | |||
+-------------------+----------+----------+-------------+ | +-------------------+----------+----------+-------------+ | |||
| Header Field Name | Protocol | Status | Reference | | | Header Field Name | Protocol | Status | Reference | | |||
+-------------------+----------+----------+-------------+ | +-------------------+----------+----------+-------------+ | |||
| Age | http | standard | Section 3.1 | | | Age | http | standard | Section 3.1 | | |||
| Cache-Control | http | standard | Section 3.2 | | | Cache-Control | http | standard | Section 3.2 | | |||
| Expires | http | standard | Section 3.3 | | | Expires | http | standard | Section 3.3 | | |||
| Pragma | http | standard | Section 3.4 | | | Pragma | http | standard | Section 3.4 | | |||
| Vary | http | standard | Section 3.5 | | | Vary | http | standard | Section 3.5 | | |||
| Warning | http | standard | Section 3.6 | | | Warning | http | standard | Section 3.6 | | |||
+-------------------+----------+----------+-------------+ | +-------------------+----------+----------+-------------+ | |||
The change controller is: "IETF (iesg@ietf.org) - Internet | The change controller is: "IETF (iesg@ietf.org) - Internet | |||
Engineering Task Force". | Engineering Task Force". | |||
6. Security Considerations | 4. Security Considerations | |||
Caches expose additional potential vulnerabilities, since the | Caches expose additional potential vulnerabilities, since the | |||
contents of the cache represent an attractive target for malicious | contents of the cache represent an attractive target for malicious | |||
exploitation. Because cache contents persist after an HTTP request | exploitation. Because cache contents persist after an HTTP request | |||
is complete, an attack on the cache can reveal information long after | is complete, an attack on the cache can reveal information long after | |||
a user believes that the information has been removed from the | a user believes that the information has been removed from the | |||
network. Therefore, cache contents need to be protected as sensitive | network. Therefore, cache contents need to be protected as sensitive | |||
information. | information. | |||
7. Acknowledgments | 5. Acknowledgments | |||
See Section 11 of [Part1]. | See Section 11 of [Part1]. | |||
8. References | 6. References | |||
8.1. Normative References | 6.1. 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-17 | and Message Parsing", draft-ietf-httpbis-p1-messaging-18 | |||
(work in progress), October 2011. | (work in progress), January 2012. | |||
[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-17 (work in | Semantics", draft-ietf-httpbis-p2-semantics-18 (work in | |||
progress), October 2011. | progress), January 2012. | |||
[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-17 (work in | Requests", draft-ietf-httpbis-p4-conditional-18 (work in | |||
progress), October 2011. | progress), January 2012. | |||
[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-17 (work | Partial Responses", draft-ietf-httpbis-p5-range-18 (work | |||
in progress), October 2011. | in progress), January 2012. | |||
[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-17 (work in progress), | draft-ietf-httpbis-p7-auth-18 (work in progress), | |||
October 2011. | January 2012. | |||
[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. | |||
8.2. Informative References | 6.2. Informative References | |||
[RFC1305] Mills, D., "Network Time Protocol (Version 3) | [RFC1305] Mills, D., "Network Time Protocol (Version 3) | |||
Specification, Implementation", RFC 1305, March 1992. | Specification, Implementation", RFC 1305, March 1992. | |||
[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. | |||
[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration | [RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration | |||
Procedures for Message Header Fields", BCP 90, RFC 3864, | Procedures for Message Header Fields", BCP 90, RFC 3864, | |||
skipping to change at page 42, line 22 | skipping to change at page 43, line 15 | |||
C.18. Since draft-ietf-httpbis-p6-cache-16 | C.18. Since draft-ietf-httpbis-p6-cache-16 | |||
Closed issues: | Closed issues: | |||
o <http://tools.ietf.org/wg/httpbis/trac/ticket/186>: "Document | o <http://tools.ietf.org/wg/httpbis/trac/ticket/186>: "Document | |||
HTTP's error-handling philosophy" | HTTP's error-handling philosophy" | |||
o <http://tools.ietf.org/wg/httpbis/trac/ticket/317>: "Cache-Control | o <http://tools.ietf.org/wg/httpbis/trac/ticket/317>: "Cache-Control | |||
directive case sensitivity" | directive case sensitivity" | |||
C.19. Since draft-ietf-httpbis-p6-cache-17 | ||||
Closed issues: | ||||
o <http://tools.ietf.org/wg/httpbis/trac/ticket/293>: "Interaction | ||||
of request and response Cache-Control" | ||||
o <http://tools.ietf.org/wg/httpbis/trac/ticket/212>: "Refining age | ||||
for 1.1 proxy chains" | ||||
o <http://tools.ietf.org/wg/httpbis/trac/ticket/274>: "warn-code | ||||
registry" | ||||
Index | Index | |||
1 | ||||
110 Response is Stale (warn code) 31 | ||||
111 Revalidation Failed (warn code) 31 | ||||
112 Disconnected Operation (warn code) 31 | ||||
113 Heuristic Expiration (warn code) 31 | ||||
199 Miscellaneous Warning (warn code) 31 | ||||
2 | ||||
214 Transformation Applied (warn code) 31 | ||||
299 Miscellaneous Persistent Warning (warn code) 31 | ||||
A | A | |||
age 6 | age 6 | |||
Age header field 20 | Age header field 20 | |||
C | C | |||
cache 5 | cache 5 | |||
Cache Directives | Cache Directives | |||
max-age 22, 25 | max-age 22, 25 | |||
max-stale 22 | max-stale 22 | |||
min-fresh 22 | min-fresh 22 | |||
must-revalidate 25 | must-revalidate 25 | |||
no-cache 21, 24 | no-cache 22, 24 | |||
no-store 22, 24 | no-store 22, 24 | |||
no-transform 23, 25 | no-transform 23, 25 | |||
only-if-cached 23 | only-if-cached 23 | |||
private 23 | private 23 | |||
proxy-revalidate 25 | proxy-revalidate 25 | |||
public 23 | public 23 | |||
s-maxage 25 | s-maxage 25 | |||
cache entry 8 | cache entry 8 | |||
cache key 8 | cache key 8 | |||
Cache-Control header field 21 | Cache-Control header field 21 | |||
skipping to change at page 43, line 50 | skipping to change at page 45, line 19 | |||
Cache Directive 22, 25 | Cache Directive 22, 25 | |||
max-stale | max-stale | |||
Cache Directive 22 | Cache Directive 22 | |||
min-fresh | min-fresh | |||
Cache Directive 22 | Cache Directive 22 | |||
must-revalidate | must-revalidate | |||
Cache Directive 25 | Cache Directive 25 | |||
N | N | |||
no-cache | no-cache | |||
Cache Directive 21, 24 | Cache Directive 22, 24 | |||
no-store | no-store | |||
Cache Directive 22, 24 | Cache Directive 22, 24 | |||
no-transform | no-transform | |||
Cache Directive 23, 25 | Cache Directive 23, 25 | |||
O | O | |||
only-if-cached | only-if-cached | |||
Cache Directive 23 | Cache Directive 23 | |||
P | P | |||
skipping to change at page 44, line 35 | skipping to change at page 46, line 4 | |||
shared cache 5 | shared cache 5 | |||
stale 6 | stale 6 | |||
strong validator 7 | strong validator 7 | |||
V | V | |||
validator 6 | validator 6 | |||
strong 7 | strong 7 | |||
Vary header field 28 | Vary header field 28 | |||
W | W | |||
Warn Codes | ||||
110 Response is Stale 31 | ||||
111 Revalidation Failed 31 | ||||
112 Disconnected Operation 31 | ||||
113 Heuristic Expiration 31 | ||||
199 Miscellaneous Warning 31 | ||||
214 Transformation Applied 31 | ||||
299 Miscellaneous Persistent Warning 31 | ||||
Warning header field 29 | Warning header field 29 | |||
Authors' Addresses | Authors' Addresses | |||
Roy T. Fielding (editor) | Roy T. Fielding (editor) | |||
Adobe Systems Incorporated | Adobe Systems Incorporated | |||
345 Park Ave | 345 Park Ave | |||
San Jose, CA 95110 | San Jose, CA 95110 | |||
USA | USA | |||
End of changes. 52 change blocks. | ||||
94 lines changed or deleted | 183 lines changed or added | |||
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