draft-ietf-httpbis-p6-cache-08.txt | draft-ietf-httpbis-p6-cache-09.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 One Laptop per Child | Intended status: Standards Track One Laptop per Child | |||
Expires: April 29, 2010 J. Mogul | Expires: September 9, 2010 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 | |||
M. Nottingham, Ed. | M. Nottingham, Ed. | |||
J. Reschke, Ed. | J. Reschke, Ed. | |||
greenbytes | greenbytes | |||
October 26, 2009 | March 8, 2010 | |||
HTTP/1.1, part 6: Caching | HTTP/1.1, part 6: Caching | |||
draft-ietf-httpbis-p6-cache-08 | draft-ietf-httpbis-p6-cache-09 | |||
Status of this Memo | Abstract | |||
The Hypertext Transfer Protocol (HTTP) is an application-level | ||||
protocol for distributed, collaborative, hypermedia information | ||||
systems. This document is Part 6 of the seven-part specification | ||||
that defines the protocol referred to as "HTTP/1.1" and, taken | ||||
together, obsoletes RFC 2616. Part 6 defines requirements on HTTP | ||||
caches and the associated header fields that control cache behavior | ||||
or indicate cacheable response messages. | ||||
Editorial Note (To be removed by RFC Editor) | ||||
Discussion of this draft should take place on the HTTPBIS working | ||||
group mailing list (ietf-http-wg@w3.org). The current issues list is | ||||
at <http://tools.ietf.org/wg/httpbis/trac/report/11> and related | ||||
documents (including fancy diffs) can be found at | ||||
<http://tools.ietf.org/wg/httpbis/>. | ||||
The changes in this draft are summarized in Appendix C.10. | ||||
Status of this Memo | ||||
This Internet-Draft is submitted to IETF in full conformance with the | This Internet-Draft is submitted to IETF in full conformance with the | |||
provisions of BCP 78 and BCP 79. This document may contain material | provisions of BCP 78 and BCP 79. | |||
from IETF Documents or IETF Contributions published or made publicly | ||||
available before November 10, 2008. The person(s) controlling the | ||||
copyright in some of this material may not have granted the IETF | ||||
Trust the right to allow modifications of such material outside the | ||||
IETF Standards Process. Without obtaining an adequate license from | ||||
the person(s) controlling the copyright in such materials, this | ||||
document may not be modified outside the IETF Standards Process, and | ||||
derivative works of it may not be created outside the IETF Standards | ||||
Process, except to format it for publication as an RFC or to | ||||
translate it into languages other than English. | ||||
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 | |||
other groups may also distribute working documents as Internet- | other groups may also distribute working documents as Internet- | |||
Drafts. | Drafts. | |||
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." | |||
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 April 29, 2010. | This Internet-Draft will expire on September 9, 2010. | |||
Copyright Notice | Copyright Notice | |||
Copyright (c) 2009 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 in effect on the date of | Provisions Relating to IETF Documents | |||
publication of this document (http://trustee.ietf.org/license-info). | (http://trustee.ietf.org/license-info) in effect on the date of | |||
Please review these documents carefully, as they describe your rights | publication of this document. Please review these documents | |||
and restrictions with respect to this document. | carefully, as they describe your rights and restrictions with respect | |||
to this document. Code Components extracted from this document must | ||||
Abstract | include Simplified BSD License text as described in Section 4.e of | |||
the Trust Legal Provisions and are provided without warranty as | ||||
The Hypertext Transfer Protocol (HTTP) is an application-level | described in the BSD License. | |||
protocol for distributed, collaborative, hypermedia information | ||||
systems. This document is Part 6 of the seven-part specification | ||||
that defines the protocol referred to as "HTTP/1.1" and, taken | ||||
together, obsoletes RFC 2616. Part 6 defines requirements on HTTP | ||||
caches and the associated header fields that control cache behavior | ||||
or indicate cacheable response messages. | ||||
Editorial Note (To be removed by RFC Editor) | ||||
Discussion of this draft should take place on the HTTPBIS working | ||||
group mailing list (ietf-http-wg@w3.org). The current issues list is | ||||
at <http://tools.ietf.org/wg/httpbis/trac/report/11> and related | ||||
documents (including fancy diffs) can be found at | ||||
<http://tools.ietf.org/wg/httpbis/>. | ||||
The changes in this draft are summarized in Appendix C.9. | This document may contain material from IETF Documents or IETF | |||
Contributions published or made publicly available before November | ||||
10, 2008. The person(s) controlling the copyright in some of this | ||||
material may not have granted the IETF Trust the right to allow | ||||
modifications of such material outside the IETF Standards Process. | ||||
Without obtaining an adequate license from the person(s) controlling | ||||
the copyright in such materials, this document may not be modified | ||||
outside the IETF Standards Process, and derivative works of it may | ||||
not be created outside the IETF Standards Process, except to format | ||||
it for publication as an RFC or to translate it into languages other | ||||
than English. | ||||
Table of Contents | Table of Contents | |||
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 | 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 | |||
1.1. Purpose . . . . . . . . . . . . . . . . . . . . . . . . . 5 | 1.1. Purpose . . . . . . . . . . . . . . . . . . . . . . . . . 5 | |||
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 | 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 | |||
1.3. Requirements . . . . . . . . . . . . . . . . . . . . . . . 6 | 1.3. Requirements . . . . . . . . . . . . . . . . . . . . . . . 6 | |||
1.4. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 7 | 1.4. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 7 | |||
1.4.1. Core Rules . . . . . . . . . . . . . . . . . . . . . . 7 | 1.4.1. Core Rules . . . . . . . . . . . . . . . . . . . . . . 7 | |||
1.4.2. ABNF Rules defined in other Parts of the | 1.4.2. ABNF Rules defined in other Parts of the | |||
Specification . . . . . . . . . . . . . . . . . . . . 7 | Specification . . . . . . . . . . . . . . . . . . . . 7 | |||
2. Cache Operation . . . . . . . . . . . . . . . . . . . . . . . 7 | 2. Cache Operation . . . . . . . . . . . . . . . . . . . . . . . 7 | |||
2.1. Response Cacheability . . . . . . . . . . . . . . . . . . 7 | 2.1. Response Cacheability . . . . . . . . . . . . . . . . . . 7 | |||
2.1.1. Storing Partial and Incomplete Responses . . . . . . . 8 | 2.1.1. Storing Partial and Incomplete Responses . . . . . . . 8 | |||
2.2. Constructing Responses from Caches . . . . . . . . . . . . 8 | 2.2. Constructing Responses from Caches . . . . . . . . . . . . 9 | |||
2.3. Freshness Model . . . . . . . . . . . . . . . . . . . . . 9 | 2.3. Freshness Model . . . . . . . . . . . . . . . . . . . . . 10 | |||
2.3.1. Calculating Freshness Lifetime . . . . . . . . . . . . 10 | 2.3.1. Calculating Freshness Lifetime . . . . . . . . . . . . 11 | |||
2.3.2. Calculating Age . . . . . . . . . . . . . . . . . . . 11 | 2.3.2. Calculating Age . . . . . . . . . . . . . . . . . . . 12 | |||
2.3.3. Serving Stale Responses . . . . . . . . . . . . . . . 13 | 2.3.3. Serving Stale Responses . . . . . . . . . . . . . . . 13 | |||
2.4. Validation Model . . . . . . . . . . . . . . . . . . . . . 13 | 2.4. Validation Model . . . . . . . . . . . . . . . . . . . . . 14 | |||
2.5. Request Methods that Invalidate . . . . . . . . . . . . . 14 | 2.5. Request Methods that Invalidate . . . . . . . . . . . . . 14 | |||
2.6. Caching Negotiated Responses . . . . . . . . . . . . . . . 15 | 2.6. Caching Negotiated Responses . . . . . . . . . . . . . . . 15 | |||
2.7. Combining Responses . . . . . . . . . . . . . . . . . . . 16 | 2.7. Combining Responses . . . . . . . . . . . . . . . . . . . 16 | |||
3. Header Field Definitions . . . . . . . . . . . . . . . . . . . 16 | 3. Header Field Definitions . . . . . . . . . . . . . . . . . . . 17 | |||
3.1. Age . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 | 3.1. Age . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 | |||
3.2. Cache-Control . . . . . . . . . . . . . . . . . . . . . . 17 | 3.2. Cache-Control . . . . . . . . . . . . . . . . . . . . . . 18 | |||
3.2.1. Request Cache-Control Directives . . . . . . . . . . . 18 | 3.2.1. Request Cache-Control Directives . . . . . . . . . . . 18 | |||
3.2.2. Response Cache-Control Directives . . . . . . . . . . 20 | 3.2.2. Response Cache-Control Directives . . . . . . . . . . 20 | |||
3.2.3. Cache Control Extensions . . . . . . . . . . . . . . . 22 | 3.2.3. Cache Control Extensions . . . . . . . . . . . . . . . 22 | |||
3.3. Expires . . . . . . . . . . . . . . . . . . . . . . . . . 23 | 3.3. Expires . . . . . . . . . . . . . . . . . . . . . . . . . 23 | |||
3.4. Pragma . . . . . . . . . . . . . . . . . . . . . . . . . . 24 | 3.4. Pragma . . . . . . . . . . . . . . . . . . . . . . . . . . 24 | |||
3.5. Vary . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 | 3.5. Vary . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 | |||
3.6. Warning . . . . . . . . . . . . . . . . . . . . . . . . . 25 | 3.6. Warning . . . . . . . . . . . . . . . . . . . . . . . . . 25 | |||
4. History Lists . . . . . . . . . . . . . . . . . . . . . . . . 28 | 4. History Lists . . . . . . . . . . . . . . . . . . . . . . . . 28 | |||
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28 | 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 28 | |||
5.1. Message Header Registration . . . . . . . . . . . . . . . 28 | 5.1. Message Header Registration . . . . . . . . . . . . . . . 28 | |||
6. Security Considerations . . . . . . . . . . . . . . . . . . . 29 | 6. Security Considerations . . . . . . . . . . . . . . . . . . . 28 | |||
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29 | 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 29 | |||
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29 | 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 29 | |||
8.1. Normative References . . . . . . . . . . . . . . . . . . . 29 | 8.1. Normative References . . . . . . . . . . . . . . . . . . . 29 | |||
8.2. Informative References . . . . . . . . . . . . . . . . . . 30 | 8.2. Informative References . . . . . . . . . . . . . . . . . . 30 | |||
Appendix A. Compatibility with Previous Versions . . . . . . . . 30 | Appendix A. Compatibility with Previous Versions . . . . . . . . 30 | |||
A.1. Changes from RFC 2068 . . . . . . . . . . . . . . . . . . 31 | A.1. Changes from RFC 2068 . . . . . . . . . . . . . . . . . . 30 | |||
A.2. Changes from RFC 2616 . . . . . . . . . . . . . . . . . . 31 | A.2. Changes from RFC 2616 . . . . . . . . . . . . . . . . . . 30 | |||
Appendix B. Collected ABNF . . . . . . . . . . . . . . . . . . . 31 | Appendix B. Collected ABNF . . . . . . . . . . . . . . . . . . . 31 | |||
Appendix C. Change Log (to be removed by RFC Editor before | Appendix C. Change Log (to be removed by RFC Editor before | |||
publication) . . . . . . . . . . . . . . . . . . . . 33 | publication) . . . . . . . . . . . . . . . . . . . . 32 | |||
C.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 33 | C.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 32 | |||
C.2. Since draft-ietf-httpbis-p6-cache-00 . . . . . . . . . . . 33 | C.2. Since draft-ietf-httpbis-p6-cache-00 . . . . . . . . . . . 32 | |||
C.3. Since draft-ietf-httpbis-p6-cache-01 . . . . . . . . . . . 34 | C.3. Since draft-ietf-httpbis-p6-cache-01 . . . . . . . . . . . 33 | |||
C.4. Since draft-ietf-httpbis-p6-cache-02 . . . . . . . . . . . 34 | C.4. Since draft-ietf-httpbis-p6-cache-02 . . . . . . . . . . . 33 | |||
C.5. Since draft-ietf-httpbis-p6-cache-03 . . . . . . . . . . . 34 | C.5. Since draft-ietf-httpbis-p6-cache-03 . . . . . . . . . . . 34 | |||
C.6. Since draft-ietf-httpbis-p6-cache-04 . . . . . . . . . . . 35 | C.6. Since draft-ietf-httpbis-p6-cache-04 . . . . . . . . . . . 34 | |||
C.7. Since draft-ietf-httpbis-p6-cache-05 . . . . . . . . . . . 35 | C.7. Since draft-ietf-httpbis-p6-cache-05 . . . . . . . . . . . 34 | |||
C.8. Since draft-ietf-httpbis-p6-cache-06 . . . . . . . . . . . 35 | C.8. Since draft-ietf-httpbis-p6-cache-06 . . . . . . . . . . . 35 | |||
C.9. Since draft-ietf-httpbis-p6-cache-07 . . . . . . . . . . . 36 | C.9. Since draft-ietf-httpbis-p6-cache-07 . . . . . . . . . . . 35 | |||
C.10. Since draft-ietf-httpbis-p6-cache-08 . . . . . . . . . . . 35 | ||||
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 | Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 | |||
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 38 | Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 38 | |||
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. | |||
skipping to change at page 8, line 5 | skipping to change at page 8, line 5 | |||
port = <port, defined in [Part1], Section 2.6> | port = <port, defined in [Part1], Section 2.6> | |||
pseudonym = <pseudonym, defined in [Part1], Section 9.9> | pseudonym = <pseudonym, defined in [Part1], Section 9.9> | |||
uri-host = <uri-host, defined in [Part1], Section 2.6> | uri-host = <uri-host, defined in [Part1], Section 2.6> | |||
2. Cache Operation | 2. Cache Operation | |||
2.1. Response Cacheability | 2.1. Response Cacheability | |||
A cache MUST NOT store a response to any request, unless: | A cache MUST NOT store a response to any request, unless: | |||
o The request method is defined as being cacheable, and | o The request method is understood by the cache and defined as being | |||
cacheable, and | ||||
o the response status code is understood by the cache, and | ||||
o the "no-store" cache directive (see Section 3.2) does not appear | o the "no-store" cache directive (see Section 3.2) does not appear | |||
in request or response headers, and | in request or response headers, and | |||
o the "private" cache response directive (see Section 3.2 does not | o the "private" cache response directive (see Section 3.2.2 does not | |||
appear in the response, if the cache is shared, and | appear in the response, if the cache is shared, and | |||
o the "Authorization" header (see Section 3.1 of [Part7]) does not | o the "Authorization" header (see Section 3.1 of [Part7]) does not | |||
appear in the request, if the cache is shared (unless the "public" | appear in the request, if the cache is shared (unless the "public" | |||
directive is present; see Section 3.2), and | directive is present; see Section 3.2), and | |||
o the cache understands partial responses, if the response is | o the response either: | |||
partial or incomplete (see Section 2.1.1). | ||||
* contains an Expires header (see Section 3.3), or | ||||
* contains a max-age response cache directive (see | ||||
Section 3.2.2), or | ||||
* contains a s-maxage response cache directive and the cache is | ||||
shared, or | ||||
* contains a Cache Control Extension (see Section 3.2.3) that | ||||
allows it to be cached, or | ||||
* has a status code that can be served with heuristic freshness | ||||
(see Section 2.3.1.1). | ||||
In this context, a cache has "understood" a request method or a | ||||
response status code if it recognises it and implements any cache- | ||||
specific behaviour. In particular, 206 Partial Content responses | ||||
cannot be cached by an implementation that does not handle partial | ||||
content (see Section 2.1.1). | ||||
Note that in normal operation, most caches will not store a response | Note that in normal operation, most caches will not store a response | |||
that has neither a cache validator nor an explicit expiration time, | that has neither a cache validator nor an explicit expiration time, | |||
as such responses are not usually useful to store. However, caches | as such responses are not usually useful to store. However, caches | |||
are not prohibited from storing such responses. | are not prohibited from storing such responses. | |||
2.1.1. Storing Partial and Incomplete Responses | 2.1.1. Storing Partial and Incomplete Responses | |||
A cache that receives an incomplete response (for example, with fewer | A cache that receives an incomplete response (for example, with fewer | |||
bytes of data than specified in a Content-Length header) can store | bytes of data than specified in a Content-Length header) can store | |||
skipping to change at page 9, line 25 | skipping to change at page 9, line 47 | |||
* 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). | |||
[[TODO-method-cacheability: define method cacheability for GET, HEAD | [[TODO-method-cacheability: define method cacheability for GET, HEAD | |||
and POST in p2-semantics.]] | and POST in p2-semantics.]] | |||
When a stored response is used to satisfy a request, caches MUST | When a stored response is used to satisfy a request, caches MUST | |||
include a single Age header field (Section 3.1) in the response with | include a single Age header field (Section 3.1) in the response with | |||
a value equal to the stored response's current_age; see | a value equal to the stored response's current_age; see | |||
Section 2.3.2. [[anchor1: DISCUSS: this currently includes | Section 2.3.2. [[DISCUSS-includes-validated: this currently includes | |||
successfully validated responses.]] | successfully validated responses.]] | |||
Requests with methods that are unsafe (Section 7.1.1 of [Part2]) MUST | Requests with methods that are unsafe (Section 7.1.1 of [Part2]) MUST | |||
be written through the cache to the origin server; i.e., A cache must | be written through the cache to the origin server; i.e., a cache must | |||
not reply to such a request before having forwarded the request and | not reply to such a request before having forwarded the request and | |||
having received a corresponding response. | having received a corresponding response. | |||
Also, note that unsafe requests might invalidate already stored | Also, note that unsafe requests might invalidate already stored | |||
responses; see Section 2.5. | responses; see Section 2.5. | |||
Caches MUST use the most recent response (as determined by the Date | Caches MUST use the most recent response (as determined by the Date | |||
header) when more than one suitable response is stored. They can | header) when more than one suitable response is stored. They can | |||
also forward a request with "Cache-Control: max-age=0" or "Cache- | also forward a request with "Cache-Control: max-age=0" or "Cache- | |||
Control: no-cache" to disambiguate which response to use. | Control: no-cache" to disambiguate which response to use. | |||
skipping to change at page 10, line 12 | skipping to change at page 10, line 34 | |||
server to provide an explicit expiration time in the future, using | server to provide an explicit expiration time in the future, using | |||
either the Expires header (Section 3.3) or the max-age response cache | either the Expires header (Section 3.3) or the max-age response cache | |||
directive (Section 3.2.2). Generally, origin servers will assign | directive (Section 3.2.2). Generally, origin servers will assign | |||
future explicit expiration times to responses in the belief that the | future explicit expiration times to responses in the belief that the | |||
entity is not likely to change in a semantically significant way | entity is not likely to change in a semantically significant way | |||
before the expiration time is reached. | before the expiration time is reached. | |||
If an origin server wishes to force a cache to validate every | If an origin server wishes to force a cache to validate every | |||
request, it can assign an explicit expiration time in the past. This | request, it can assign an explicit expiration time in the past. This | |||
means that the response is always stale, so that caches should | means that the response is always stale, so that caches should | |||
validate it before using it for subsequent requests. [[anchor2: This | validate it before using it for subsequent requests. [[TODO- | |||
wording may cause confusion, because the response may still be served | response-stale: This wording may cause confusion, because the | |||
stale.]] | response may still be served stale.]] | |||
Since origin servers do not always provide explicit expiration times, | Since origin servers do not always provide explicit expiration times, | |||
HTTP caches may also assign heuristic expiration times when they are | HTTP caches may also assign heuristic expiration times when they are | |||
not specified, employing algorithms that use other header values | not specified, employing algorithms that use other header values | |||
(such as the Last-Modified time) to estimate a plausible expiration | (such as the Last-Modified time) to estimate a plausible expiration | |||
time. The HTTP/1.1 specification does not provide specific | time. The HTTP/1.1 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 may need to influence freshness calculation. | Additionally, clients may need to influence freshness calculation. | |||
They can do this using several request cache directives, with the | They can do this using several request cache directives, with the | |||
effect of either increasing or loosening constraints on freshness. | effect of either increasing or loosening constraints on freshness. | |||
See Section 3.2.1. | See Section 3.2.1. | |||
[[anchor3: ISSUE: there are not requirements directly applying to | [[ISSUE-no-req-for-directives: there are not requirements directly | |||
cache-request-directives and freshness.]] | applying to cache-request-directives and freshness.]] | |||
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 4 for an explanation of the difference between | |||
caches and history mechanisms. | 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: | |||
skipping to change at page 11, line 34 | skipping to change at page 12, line 6 | |||
When a heuristic is used to calculate freshness lifetime, the cache | When a heuristic is used to calculate freshness lifetime, the cache | |||
SHOULD attach a Warning header with a 113 warn-code to the response | SHOULD attach a Warning header with a 113 warn-code to the response | |||
if its current_age is more than 24 hours and such a warning is not | if its current_age is more than 24 hours and such a warning is not | |||
already present. | already present. | |||
Also, if the response has a Last-Modified header (Section 6.6 of | Also, if the response has a Last-Modified header (Section 6.6 of | |||
[Part4]), the heuristic expiration value SHOULD be no more than some | [Part4]), the heuristic expiration value SHOULD be no more than some | |||
fraction of the interval since that time. A typical setting of this | fraction of the interval since that time. A typical setting of this | |||
fraction might be 10%. | fraction might be 10%. | |||
[[anchor4: REVIEW: took away HTTP/1.0 query string heuristic | [[REVIEW-query-string-heuristics: took away HTTP/1.0 query string | |||
uncacheability.]] | heuristic uncacheability.]] | |||
2.3.2. Calculating Age | 2.3.2. Calculating Age | |||
HTTP/1.1 uses the Age response-header to convey the estimated age of | HTTP/1.1 uses the Age response-header to convey the estimated age of | |||
the response message when obtained from a cache. The Age field value | the response message when obtained from a cache. The Age field value | |||
is the cache's estimate of the amount of time since the response was | is the cache's estimate of the amount of time since the response was | |||
generated or validated by the origin server. In essence, the Age | generated or validated by the origin server. In essence, the Age | |||
value is the sum of the time that the response has been resident in | value is the sum of the time that the response has been resident in | |||
each of the caches along the path from the origin server, plus the | each of the caches along the path from the origin server, plus the | |||
amount of time it has been in transit along network paths. | amount of time it has been in transit along network paths. | |||
skipping to change at page 14, line 26 | skipping to change at page 14, line 37 | |||
contains only partial content, its entity-tag SHOULD NOT be included | contains only partial content, its entity-tag SHOULD NOT be included | |||
in the If-None-Match header field unless the request is for a range | in the If-None-Match header field unless the request is for a range | |||
that would be fully satisfied by that stored response. | that would be fully satisfied by that stored response. | |||
A 304 (Not Modified) response status code indicates that the stored | A 304 (Not Modified) response status code indicates that the stored | |||
response can be updated and reused; see Section 2.7. | response can be updated and reused; see Section 2.7. | |||
A full response (i.e., one with a response body) indicates that none | A full response (i.e., one with a response body) indicates that none | |||
of the stored responses nominated in the conditional request is | of the stored responses nominated in the conditional request is | |||
suitable. Instead, the full response is used both to satisfy the | suitable. Instead, the full response is used both to satisfy the | |||
request and replace the stored response. [[anchor5: Should there be a | request and replace the stored response. [[TODO-req-missing: Should | |||
requirement here?]] | there be a requirement here?]] | |||
If a cache receives a 5xx response while attempting to validate a | If a cache receives a 5xx response while attempting to validate a | |||
response, it MAY either forward this response to the requesting | response, it MAY either forward this response to the requesting | |||
client, or act as if the server failed to respond. In the latter | client, or act as if the server failed to respond. In the latter | |||
case, it MAY return a previously stored response (see Section 2.3.3). | case, it MAY return a previously stored response (see Section 2.3.3). | |||
2.5. Request Methods that Invalidate | 2.5. Request Methods that Invalidate | |||
Because unsafe methods (Section 7.1.1 of [Part2]) have the potential | Because unsafe methods (Section 7.1.1 of [Part2]) have the potential | |||
for changing state on the origin server, intervening caches can use | for changing state on the origin server, intervening caches can use | |||
skipping to change at page 15, line 7 | skipping to change at page 15, line 18 | |||
o DELETE | o DELETE | |||
o POST | o POST | |||
An invalidation based on a URI from a Location or Content-Location | An invalidation based on a URI from a Location or Content-Location | |||
header MUST NOT be performed if the host part of that URI differs | header MUST NOT be performed if the host part of that URI differs | |||
from the host part in the Request-URI. This helps prevent denial of | from the host part in the Request-URI. This helps prevent denial of | |||
service attacks. | service attacks. | |||
[[anchor6: TODO: "host part" needs to be specified better.]] | [[TODO-def-host-part: "host part" needs to be specified better.]] | |||
A cache that passes through requests for methods it does not | A cache that passes through requests for methods it does not | |||
understand SHOULD invalidate the Request-URI. | understand SHOULD invalidate the Request-URI. | |||
Here, "invalidate" means that the cache will either remove all stored | Here, "invalidate" means that the cache will either remove all stored | |||
responses related to the Request-URI, or will mark these as "invalid" | responses related to the Request-URI, or will mark these as "invalid" | |||
and in need of a mandatory validation before they can be returned in | and in need of a mandatory validation before they can be returned in | |||
response to a subsequent request. | response to a subsequent request. | |||
Note that this does not guarantee that all appropriate responses are | Note that this does not guarantee that all appropriate responses are | |||
invalidated. For example, the request that caused the change at the | invalidated. For example, the request that caused the change at the | |||
origin server might not have gone through the cache where a response | origin server might not have gone through the cache where a response | |||
is stored. | is stored. | |||
[[anchor7: TODO: specify that only successful (2xx, 3xx?) responses | [[TODO-spec-success-invalidate: specify that only successful (2xx, | |||
invalidate.]] | 3xx?) responses invalidate.]] | |||
2.6. Caching Negotiated Responses | 2.6. Caching Negotiated Responses | |||
When a cache receives a request that can be satisfied by a stored | When a cache receives a request that can be satisfied by a stored | |||
response that has a Vary header field (Section 3.5), it MUST NOT use | response that has a Vary header field (Section 3.5), it MUST NOT use | |||
that response unless all of the selecting request-headers nominated | that response unless all of the selecting request-headers nominated | |||
by the Vary header match in both the original request (i.e., that | by the Vary header match in both the original request (i.e., that | |||
associated with the stored response), and the presented request. | associated with the stored response), and the presented request. | |||
The selecting request-headers from two requests are defined to match | The selecting request-headers from two requests are defined to match | |||
if and only if the selecting request-headers in the first request can | if and only if those in the first request can be transformed to those | |||
be transformed to the selecting request-headers in the second request | in the second request by applying any of the following: | |||
by adding or removing linear white space [[anchor8: [ref]]] at places | ||||
where this is allowed by the corresponding ABNF, and/or combining | ||||
multiple message-header fields with the same field name following the | ||||
rules about header fields in Section 3.2 of [Part1]. | ||||
If a header field is absent from a request, it can only match another | o adding or removing whitespace, where allowed in the header's | |||
request if it is also absent there. | syntax | |||
o combining multiple message-header fields with the same field name | ||||
(see Section 3.2 of [Part1]) | ||||
o normalizing both header values in a way that is known to have | ||||
identical semantics, according to the header's specification | ||||
(e.g., re-ordering field values when order is not significant; | ||||
case-normalization, where values are defined to be case- | ||||
insensitive) | ||||
If (after any normalisation that may take place) a header field is | ||||
absent from a request, it can only match another request if it is | ||||
also absent there. | ||||
A Vary header field-value of "*" always fails to match, and | A Vary header field-value of "*" always fails to match, and | |||
subsequent requests to that resource can only be properly interpreted | subsequent requests to that resource can only be properly interpreted | |||
by the origin server. | by the origin server. | |||
The stored response with matching selecting request-headers is known | The stored response with matching selecting request-headers is known | |||
as the selected response. | as the selected response. | |||
If no selected response is available, the cache MAY forward the | If no selected response is available, the cache MAY forward the | |||
presented request to the origin server in a conditional request; see | presented request to the origin server in a conditional request; see | |||
skipping to change at page 16, line 16 | skipping to change at page 16, line 38 | |||
2.7. Combining Responses | 2.7. Combining Responses | |||
When a cache receives a 304 (Not Modified) response or a 206 (Partial | When a cache receives a 304 (Not Modified) response or a 206 (Partial | |||
Content) response (in this section, the "new" response"), it needs to | Content) response (in this section, the "new" response"), it needs to | |||
created an updated response by combining the stored response with the | created an updated response by combining the stored response with the | |||
new one, so that the updated response can be used to satisfy the | new one, so that the updated response can be used to satisfy the | |||
request. | request. | |||
If the new response contains an ETag, it identifies the stored | If the new response contains an ETag, it identifies the stored | |||
response to use. [[anchor9: may need language about Content-Location | response to use. [[TODO-mention-CL: may need language about Content- | |||
here]][[anchor10: cover case where INM with multiple etags was sent]] | Location here]][[TODO-inm-mult-etags: cover case where INM with | |||
multiple etags was sent]] | ||||
If the status code is 206 (partial content), both the stored and new | If the status code is 206 (partial content), both the stored and new | |||
responses MUST have validators, and those validators MUST match using | responses MUST have validators, and those validators MUST match using | |||
the strong comparison function (see Section 4 of [Part4]). | the strong comparison function (see Section 4 of [Part4]). | |||
Otherwise, the responses MUST NOT be combined. | Otherwise, the responses MUST NOT be combined. | |||
The stored response headers are used as those of the updated | The stored response headers are used as those of the updated | |||
response, except that | response, except that | |||
o any stored Warning headers with warn-code 1xx (see Section 3.6) | o any stored Warning headers with warn-code 1xx (see Section 3.6) | |||
skipping to change at page 16, line 40 | skipping to change at page 17, line 15 | |||
o any stored Warning headers with warn-code 2xx MUST be retained in | o any stored Warning headers with warn-code 2xx MUST be retained in | |||
the stored response and the updated response. | the stored response and the updated response. | |||
o any headers provided in the new response MUST replace the | o any headers provided in the new response MUST replace the | |||
corresponding headers from the stored response. | corresponding headers from the stored response. | |||
If a header field-name in the new response matches more than one | If a header field-name in the new response matches more than one | |||
header in the stored response, all such stored headers MUST be | header in the stored response, all such stored headers MUST be | |||
replaced. | replaced. | |||
The updated response can [[[[anchor11: requirement?]]]] be used to | The updated response can [[TODO-is-req: requirement?]] be used to | |||
replace the stored response in cache. In the case of a 206 response, | replace the stored response in cache. In the case of a 206 response, | |||
the combined entity-body MAY be stored. | the combined entity-body MAY be stored. | |||
[[anchor12: ISSUE: discuss how to handle HEAD updates]] | [[ISSUE-how-head: discuss how to handle HEAD updates]] | |||
3. Header Field Definitions | 3. Header Field Definitions | |||
This section defines the syntax and semantics of HTTP/1.1 header | This section defines the syntax and semantics of HTTP/1.1 header | |||
fields related to caching. | fields related to caching. | |||
For entity-header fields, both sender and recipient refer to either | For entity-header fields, both sender and recipient refer to either | |||
the client or the server, depending on who sends and who receives the | the client or the server, depending on who sends and who receives the | |||
entity. | entity. | |||
skipping to change at page 19, line 13 | skipping to change at page 19, line 32 | |||
client is not willing to accept a stale response. | client is not willing to accept a stale response. | |||
max-stale | max-stale | |||
The max-stale request directive indicates that the client is | The max-stale request directive indicates that the client is | |||
willing to accept a response that has exceeded its expiration | willing to accept a response that has exceeded its expiration | |||
time. If max-stale is assigned a value, then the client is | time. If max-stale is assigned a value, then the client is | |||
willing to accept a response that has exceeded its expiration time | willing to accept a response that has exceeded its expiration time | |||
by no more than the specified number of seconds. If no value is | by no more than the specified number of seconds. If no value is | |||
assigned to max-stale, then the client is willing to accept a | assigned to max-stale, then the client is willing to accept a | |||
stale response of any age. [[anchor13: of any staleness? --mnot]] | stale response of any age. [[TODO-staleness: of any staleness? | |||
--mnot]] | ||||
min-fresh | min-fresh | |||
The min-fresh request directive indicates that the client is | The min-fresh request directive indicates that the client is | |||
willing to accept a response whose freshness lifetime is no less | willing to accept a response whose freshness lifetime is no less | |||
than its current age plus the specified time in seconds. That is, | than its current age plus the specified time in seconds. That is, | |||
the client wants a response that will still be fresh for at least | the client wants a response that will still be fresh for at least | |||
the specified number of seconds. | the specified number of seconds. | |||
no-transform | no-transform | |||
skipping to change at page 20, line 42 | skipping to change at page 20, line 50 | |||
If the private response directive specifies one or more field- | If the private response directive specifies one or more field- | |||
names, this requirement is limited to the field-values associated | names, this requirement is limited to the field-values associated | |||
with the listed response headers. That is, the specified field- | with the listed response headers. That is, the specified field- | |||
names(s) MUST NOT be stored by a shared cache, whereas the | names(s) MUST NOT be stored by a shared cache, whereas the | |||
remainder of the response message MAY be. | remainder of the response message MAY be. | |||
Note: This usage of the word private only controls where the | Note: This usage of the word private only controls where the | |||
response may be stored, and cannot ensure the privacy of the | response may be stored, and cannot ensure the privacy of the | |||
message content. Also, private response directives with field- | message content. Also, private response directives with field- | |||
names are often handled by implementations as if an unqualified | names are often handled by implementations as if an unqualified | |||
private directive was recieved; i.e., the special handling for the | private directive was received; i.e., the special handling for the | |||
qualified form is not widely implemented. | qualified form is not widely implemented. | |||
no-cache | no-cache | |||
The no-cache response directive indicates that the response MUST | The no-cache response directive indicates that the response MUST | |||
NOT be used to satisfy a subsequent request without successful | NOT be used to satisfy a subsequent request without successful | |||
validation on the origin server. This allows an origin server to | validation on the origin server. This allows an origin server to | |||
prevent caching even by caches that have been configured to return | prevent caching even by caches that have been configured to return | |||
stale responses. | stale responses. | |||
skipping to change at page 21, line 17 | skipping to change at page 21, line 25 | |||
with the listed response headers. That is, the specified field- | with the listed response headers. That is, the specified field- | |||
name(s) MUST NOT be sent in the response to a subsequent request | name(s) MUST NOT be sent in the response to a subsequent request | |||
without successful validation on the origin server. This allows | without successful validation on the origin server. This allows | |||
an origin server to prevent the re-use of certain header fields in | an origin server to prevent the re-use of certain header fields in | |||
a response, while still allowing caching of the rest of the | a response, while still allowing caching of the rest of the | |||
response. | response. | |||
Note: Most HTTP/1.0 caches will not recognize or obey this | Note: Most HTTP/1.0 caches will not recognize or obey this | |||
directive. Also, no-cache response directives with field-names | directive. Also, no-cache response directives with field-names | |||
are often handled by implementations as if an unqualified no-cache | are often handled by implementations as if an unqualified no-cache | |||
directive was recieved; i.e., the special handling for the | directive was received; i.e., the special handling for the | |||
qualified form is not widely implemented. | qualified form is not widely implemented. | |||
no-store | no-store | |||
The no-store response directive indicates that a cache MUST NOT | The no-store response directive indicates that a cache MUST NOT | |||
store any part of either the immediate request or response. This | store any part of either the immediate request or response. This | |||
directive applies to both non-shared and shared caches. "MUST NOT | directive applies to both non-shared and shared caches. "MUST NOT | |||
store" in this context means that the cache MUST NOT intentionally | store" in this context means that the cache MUST NOT intentionally | |||
store the information in non-volatile storage, and MUST make a | store the information in non-volatile storage, and MUST make a | |||
best-effort attempt to remove the information from volatile | best-effort attempt to remove the information from volatile | |||
skipping to change at page 23, line 41 | skipping to change at page 24, line 4 | |||
The field-value is an absolute date and time as defined by HTTP-date | The field-value is an absolute date and time as defined by HTTP-date | |||
in Section 6.1 of [Part1]; it MUST be sent in rfc1123-date format. | in Section 6.1 of [Part1]; it MUST be sent in rfc1123-date format. | |||
Expires = "Expires" ":" OWS Expires-v | Expires = "Expires" ":" OWS Expires-v | |||
Expires-v = HTTP-date | Expires-v = HTTP-date | |||
For example | For example | |||
Expires: Thu, 01 Dec 1994 16:00:00 GMT | Expires: Thu, 01 Dec 1994 16:00:00 GMT | |||
Note: If a response includes a Cache-Control field with the max- | ||||
Note: if a response includes a Cache-Control field with the max- | ||||
age directive (see Section 3.2.2), that directive overrides the | age directive (see Section 3.2.2), that directive overrides the | |||
Expires field. Likewise, the s-maxage directive overrides Expires | Expires field. Likewise, the s-maxage directive overrides Expires | |||
in shared caches. | in shared caches. | |||
HTTP/1.1 servers SHOULD NOT send Expires dates more than one year in | HTTP/1.1 servers SHOULD NOT send Expires dates more than one year in | |||
the future. | the future. | |||
HTTP/1.1 clients and caches MUST treat other invalid date formats, | HTTP/1.1 clients and caches MUST treat other invalid date formats, | |||
especially including the value "0", as in the past (i.e., "already | especially including the value "0", as in the past (i.e., "already | |||
expired"). | expired"). | |||
skipping to change at page 24, line 29 | skipping to change at page 24, line 39 | |||
When the no-cache directive is present in a request message, an | When the no-cache directive is present in a request message, an | |||
application SHOULD forward the request toward the origin server even | application SHOULD forward the request toward the origin server even | |||
if it has a cached copy of what is being requested. This pragma | if it has a cached copy of what is being requested. This pragma | |||
directive has the same semantics as the no-cache response directive | directive has the same semantics as the no-cache response directive | |||
(see Section 3.2.2) and is defined here for backward compatibility | (see Section 3.2.2) and is defined here for backward compatibility | |||
with HTTP/1.0. Clients SHOULD include both header fields when a no- | with HTTP/1.0. Clients SHOULD include both header fields when a no- | |||
cache request is sent to a server not known to be HTTP/1.1 compliant. | cache request is sent to a server not known to be HTTP/1.1 compliant. | |||
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". | sent "Cache-Control: no-cache". | |||
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. | |||
This mechanism is deprecated; no new Pragma directives will be | This mechanism is deprecated; no new Pragma directives will be | |||
defined in HTTP. | defined in HTTP. | |||
3.5. Vary | 3.5. Vary | |||
The "Vary" response-header field conveys the set of request-header | The "Vary" response-header field conveys the set of request-header | |||
fields that were used to select the representation. | fields that were used to select the representation. | |||
Caches use this information, in part, to determine whether a stored | Caches use this information, in part, to determine whether a stored | |||
response can be used to satisdy a given request; see Section 2.6. | response can be used to satisfy a given request; see Section 2.6. | |||
determines, while the response is fresh, whether a cache is permitted | determines, while the response is fresh, whether a cache is permitted | |||
to use the response to reply to a subsequent request without | to use the response to reply to a subsequent request without | |||
validation; see Section 2.6. | validation; see Section 2.6. | |||
In uncacheable or stale responses, the Vary field value advises the | In uncacheable or stale responses, the Vary field value advises the | |||
user agent about the criteria that were used to select the | user agent about the criteria that were used to select the | |||
representation. | representation. | |||
Vary = "Vary" ":" OWS Vary-v | Vary = "Vary" ":" OWS Vary-v | |||
Vary-v = "*" / 1#field-name | Vary-v = "*" / 1#field-name | |||
skipping to change at page 25, line 41 | skipping to change at page 25, line 51 | |||
The "Warning" general-header field is used to carry additional | The "Warning" general-header field is used to carry additional | |||
information about the status or transformation of a message that | information about the status or transformation of a message that | |||
might not be reflected in the message. This information is typically | might not be reflected in the message. This information is typically | |||
used to warn about possible incorrectness introduced by caching | used to warn about possible incorrectness introduced by caching | |||
operations or transformations applied to the entity body of the | operations or transformations applied to the entity body of the | |||
message. | message. | |||
Warnings can be used for other purposes, both cache-related and | Warnings can be used for other purposes, both cache-related and | |||
otherwise. The use of a warning, rather than an error status code, | otherwise. The use of a warning, rather than an error status code, | |||
distinguish these responses from true failures. | distinguishes these responses from true failures. | |||
Warning headers can in general be applied to any message, however | Warning headers can in general be applied to any message, however | |||
some warn-codes are specific to caches and can only be applied to | some warn-codes are specific to caches and can only be applied to | |||
response messages. | response messages. | |||
Warning = "Warning" ":" OWS Warning-v | Warning = "Warning" ":" OWS Warning-v | |||
Warning-v = 1#warning-value | Warning-v = 1#warning-value | |||
warning-value = warn-code SP warn-agent SP warn-text | warning-value = warn-code SP warn-agent SP warn-text | |||
[SP warn-date] | [SP warn-date] | |||
skipping to change at page 28, line 12 | skipping to change at page 28, line 17 | |||
The warning text can include arbitrary information to be presented | The warning text can include arbitrary information to be presented | |||
to a human user, or logged. A system receiving this warning MUST | to a human user, or logged. A system receiving this warning MUST | |||
NOT take any automated action. | NOT take any automated action. | |||
4. History Lists | 4. 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 an entity retrieved | history lists, that can be used to redisplay an entity retrieved | |||
earlier in a session. | earlier in a session. | |||
History mechanisms and caches are different. In particular history | The freshness model (Section 2.3) does not necessarily apply to | |||
mechanisms SHOULD NOT try to show a correct view of the current state | history mechanisms. I.e., a history mechanism can display a previous | |||
of a resource. Rather, a history mechanism is meant to show exactly | representation even if it has expired. | |||
what the user saw at the time when the resource was retrieved. | ||||
By default, an expiration time does not apply to history mechanisms. | ||||
If the entity is still in storage, a history mechanism SHOULD display | ||||
it even if the entity has expired, unless the user has specifically | ||||
configured the agent to refresh expired history documents. | ||||
This is not to be construed to prohibit the history mechanism from | ||||
telling the user that a view might be stale. | ||||
Note: if history list mechanisms unnecessarily prevent users from | This does not prohibit the history mechanism from telling the user | |||
viewing stale resources, this will tend to force service authors | that a view might be stale, or from honoring cache directives (e.g., | |||
to avoid using HTTP expiration controls and cache controls when | Cache-Control: no-store). | |||
they would otherwise like to. Service authors may consider it | ||||
important that users not be presented with error messages or | ||||
warning messages when they use navigation controls (such as BACK) | ||||
to view previously fetched resources. Even though sometimes such | ||||
resources ought not be cached, or ought to expire quickly, user | ||||
interface considerations may force service authors to resort to | ||||
other means of preventing caching (e.g. "once-only" URLs) in order | ||||
not to suffer the effects of improperly functioning history | ||||
mechanisms. | ||||
5. IANA Considerations | 5. IANA Considerations | |||
5.1. Message Header Registration | 5.1. Message Header Registration | |||
The Message Header Registry located at <http://www.iana.org/ | The Message Header Registry located at <http://www.iana.org/ | |||
assignments/message-headers/message-header-index.html> should be | assignments/message-headers/message-header-index.html> should be | |||
updated with the permanent registrations below (see [RFC3864]): | updated with the permanent registrations below (see [RFC3864]): | |||
+-------------------+----------+----------+-------------+ | +-------------------+----------+----------+-------------+ | |||
skipping to change at page 29, line 42 | skipping to change at page 29, line 24 | |||
suggestions and comments from individuals including: Shel Kaphan, | suggestions and comments from individuals including: Shel Kaphan, | |||
Paul Leach, Koen Holtman, David Morris, and Larry Masinter. | Paul Leach, Koen Holtman, David Morris, and Larry Masinter. | |||
8. References | 8. References | |||
8.1. Normative References | 8.1. 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-08 | and Message Parsing", draft-ietf-httpbis-p1-messaging-09 | |||
(work in progress), October 2009. | (work in progress), March 2010. | |||
[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-08 (work in | Semantics", draft-ietf-httpbis-p2-semantics-09 (work in | |||
progress), October 2009. | progress), March 2010. | |||
[Part3] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H., | ||||
Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed., | ||||
and J. Reschke, Ed., "HTTP/1.1, part 3: Message Payload | ||||
and Content Negotiation", draft-ietf-httpbis-p3-payload-08 | ||||
(work in progress), October 2009. | ||||
[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-08 (work in | Requests", draft-ietf-httpbis-p4-conditional-09 (work in | |||
progress), October 2009. | progress), March 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-08 (work | Partial Responses", draft-ietf-httpbis-p5-range-09 (work | |||
in progress), October 2009. | in progress), March 2010. | |||
[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-08 (work in progress), | draft-ietf-httpbis-p7-auth-09 (work in progress), | |||
October 2009. | March 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. | |||
8.2. Informative References | 8.2. Informative References | |||
[RFC1305] Mills, D., "Network Time Protocol (Version 3) | [RFC1305] Mills, D., "Network Time Protocol (Version 3) | |||
skipping to change at page 31, line 4 | skipping to change at page 30, line 25 | |||
[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, | |||
September 2004. | September 2004. | |||
Appendix A. Compatibility with Previous Versions | Appendix A. Compatibility with Previous Versions | |||
A.1. Changes from RFC 2068 | A.1. Changes from RFC 2068 | |||
A case was missed in the Cache-Control model of HTTP/1.1; s-maxage | A case was missed in the Cache-Control model of HTTP/1.1; s-maxage | |||
was introduced to add this missing case. (Sections 2.1, 3.2). | was introduced to add this missing case. (Sections 2.1, 3.2). | |||
Transfer-coding and message lengths all interact in ways that | ||||
required fixing exactly when chunked encoding is used (to allow for | ||||
transfer encoding that may not be self delimiting); it was important | ||||
to straighten out exactly how message lengths are computed. (see also | ||||
[Part1], [Part3] and [Part5]) [[anchor16: This used to refer to the | ||||
text about non-modifiable headers, and will have to be updated later | ||||
on. --jre]] | ||||
Proxies should be able to add Content-Length when appropriate. | ||||
[[anchor17: This used to refer to the text about non-modifiable | ||||
headers, and will have to be updated later on. --jre]] | ||||
Range request responses would become very verbose if all meta-data | Range request responses would become very verbose if all meta-data | |||
were always returned; by allowing the server to only send needed | were always returned; by allowing the server to only send needed | |||
headers in a 206 response, this problem can be avoided. | headers in a 206 response, this problem can be avoided. | |||
(Section 2.7) | (Section 2.7) | |||
The Cache-Control: max-age directive was not properly defined for | The Cache-Control: max-age directive was not properly defined for | |||
responses. (Section 3.2.2) | responses. (Section 3.2.2) | |||
Warnings could be cached incorrectly, or not updated appropriately. | Warnings could be cached incorrectly, or not updated appropriately. | |||
(Section 2.3, 2.7, 3.2, and 3.6) Warning also needed to be a general | (Section 2.3, 2.7, 3.2, and 3.6) Warning also needed to be a general | |||
skipping to change at page 36, line 21 | skipping to change at page 35, line 33 | |||
o <http://tools.ietf.org/wg/httpbis/trac/ticket/167>: "Content- | o <http://tools.ietf.org/wg/httpbis/trac/ticket/167>: "Content- | |||
Location on 304 responses" | Location on 304 responses" | |||
o <http://tools.ietf.org/wg/httpbis/trac/ticket/169>: "private and | o <http://tools.ietf.org/wg/httpbis/trac/ticket/169>: "private and | |||
no-cache CC directives with headers" | no-cache CC directives with headers" | |||
o <http://tools.ietf.org/wg/httpbis/trac/ticket/187>: "RFC2047 and | o <http://tools.ietf.org/wg/httpbis/trac/ticket/187>: "RFC2047 and | |||
warn-text" | warn-text" | |||
C.10. Since draft-ietf-httpbis-p6-cache-08 | ||||
Closed issues: | ||||
o <http://tools.ietf.org/wg/httpbis/trac/ticket/147>: "serving | ||||
negotiated responses from cache: header-specific canonicalization" | ||||
o <http://tools.ietf.org/wg/httpbis/trac/ticket/197>: "Effect of CC | ||||
directives on history lists" | ||||
Affected issues: | ||||
o <http://tools.ietf.org/wg/httpbis/trac/ticket/199>: Status codes | ||||
and caching | ||||
Partly resolved issues: | ||||
o <http://tools.ietf.org/wg/httpbis/trac/ticket/60>: "Placement of | ||||
13.5.1 and 13.5.2" | ||||
Index | Index | |||
A | A | |||
age 6 | age 6 | |||
Age header 17 | Age header 17 | |||
C | C | |||
cache 5 | cache 5 | |||
Cache Directives | Cache Directives | |||
max-age 18, 22 | max-age 19, 22 | |||
max-stale 19 | max-stale 19 | |||
min-fresh 19 | min-fresh 19 | |||
must-revalidate 21 | must-revalidate 21 | |||
no-cache 18, 20 | no-cache 18, 21 | |||
no-store 18, 21 | no-store 18, 21 | |||
no-transform 19, 22 | no-transform 19, 22 | |||
only-if-cached 19 | only-if-cached 19 | |||
private 20 | private 20 | |||
proxy-revalidate 21 | proxy-revalidate 22 | |||
public 20 | public 20 | |||
s-maxage 22 | s-maxage 22 | |||
Cache-Control header 17 | Cache-Control header 18 | |||
cacheable 5 | cacheable 5 | |||
E | E | |||
Expires header 23 | Expires header 23 | |||
explicit expiration time 5 | explicit expiration time 5 | |||
F | F | |||
first-hand 6 | first-hand 6 | |||
fresh 6 | fresh 6 | |||
freshness lifetime 6 | freshness lifetime 6 | |||
skipping to change at page 37, line 22 | skipping to change at page 37, line 5 | |||
cache-extension 18 | cache-extension 18 | |||
cache-request-directive 18 | cache-request-directive 18 | |||
cache-response-directive 20 | cache-response-directive 20 | |||
delta-seconds 17 | delta-seconds 17 | |||
Expires 23 | Expires 23 | |||
Expires-v 23 | Expires-v 23 | |||
extension-pragma 24 | extension-pragma 24 | |||
Pragma 24 | Pragma 24 | |||
pragma-directive 24 | pragma-directive 24 | |||
Pragma-v 24 | Pragma-v 24 | |||
Vary 24 | Vary 25 | |||
Vary-v 24 | Vary-v 25 | |||
warn-agent 26 | warn-agent 26 | |||
warn-code 26 | warn-code 26 | |||
warn-date 26 | warn-date 26 | |||
warn-text 26 | warn-text 26 | |||
Warning 26 | Warning 26 | |||
Warning-v 26 | Warning-v 26 | |||
warning-value 26 | warning-value 26 | |||
H | H | |||
Headers | Headers | |||
Age 17 | Age 17 | |||
Cache-Control 17 | Cache-Control 18 | |||
Expires 23 | Expires 23 | |||
Pragma 24 | Pragma 24 | |||
Vary 24 | Vary 24 | |||
Warning 25 | Warning 25 | |||
heuristic expiration time 5 | heuristic expiration time 5 | |||
M | M | |||
max-age | max-age | |||
Cache Directive 18, 22 | Cache Directive 19, 22 | |||
max-stale | max-stale | |||
Cache Directive 19 | Cache Directive 19 | |||
min-fresh | min-fresh | |||
Cache Directive 19 | Cache Directive 19 | |||
must-revalidate | must-revalidate | |||
Cache Directive 21 | Cache Directive 21 | |||
N | N | |||
no-cache | no-cache | |||
Cache Directive 18, 20 | Cache Directive 18, 21 | |||
no-store | no-store | |||
Cache Directive 18, 21 | Cache Directive 18, 21 | |||
no-transform | no-transform | |||
Cache Directive 19, 22 | Cache Directive 19, 22 | |||
O | O | |||
only-if-cached | only-if-cached | |||
Cache Directive 19 | Cache Directive 19 | |||
P | P | |||
Pragma header 24 | Pragma header 24 | |||
private | private | |||
Cache Directive 20 | Cache Directive 20 | |||
proxy-revalidate | proxy-revalidate | |||
Cache Directive 21 | Cache Directive 22 | |||
public | public | |||
Cache Directive 20 | Cache Directive 20 | |||
S | S | |||
s-maxage | s-maxage | |||
Cache Directive 22 | Cache Directive 22 | |||
stale 6 | stale 6 | |||
V | V | |||
validator 6 | validator 6 | |||
End of changes. 61 change blocks. | ||||
158 lines changed or deleted | 181 lines changed or added | |||
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