draft-ietf-httpbis-p2-semantics-10.txt   draft-ietf-httpbis-p2-semantics-11.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
Updates: 2817 (if approved) Alcatel-Lucent Updates: 2817 (if approved) Alcatel-Lucent
Intended status: Standards Track J. Mogul Intended status: Standards Track J. Mogul
Expires: January 13, 2011 HP Expires: February 5, 2011 HP
H. Frystyk H. Frystyk
Microsoft Microsoft
L. Masinter L. Masinter
Adobe Systems Adobe Systems
P. Leach P. Leach
Microsoft Microsoft
T. Berners-Lee T. Berners-Lee
W3C/MIT W3C/MIT
Y. Lafon, Ed. Y. Lafon, Ed.
W3C W3C
J. Reschke, Ed. J. Reschke, Ed.
greenbytes greenbytes
July 12, 2010 August 4, 2010
HTTP/1.1, part 2: Message Semantics HTTP/1.1, part 2: Message Semantics
draft-ietf-httpbis-p2-semantics-10 draft-ietf-httpbis-p2-semantics-11
Abstract Abstract
The Hypertext Transfer Protocol (HTTP) is an application-level The Hypertext Transfer Protocol (HTTP) is an application-level
protocol for distributed, collaborative, hypermedia information protocol for distributed, collaborative, hypermedia information
systems. HTTP has been in use by the World Wide Web global systems. HTTP has been in use by the World Wide Web global
information initiative since 1990. This document is Part 2 of the information initiative since 1990. This document is Part 2 of the
seven-part specification that defines the protocol referred to as seven-part specification that defines the protocol referred to as
"HTTP/1.1" and, taken together, obsoletes RFC 2616. Part 2 defines "HTTP/1.1" and, taken together, obsoletes RFC 2616. Part 2 defines
the semantics of HTTP messages as expressed by request methods, the semantics of HTTP messages as expressed by request methods,
skipping to change at page 1, line 46 skipping to change at page 1, line 46
fields. fields.
Editorial Note (To be removed by RFC Editor) Editorial Note (To be removed by RFC Editor)
Discussion of this draft should take place on the HTTPBIS working Discussion of this draft should take place on the HTTPBIS working
group mailing list (ietf-http-wg@w3.org). The current issues list is group mailing list (ietf-http-wg@w3.org). The current issues list is
at <http://tools.ietf.org/wg/httpbis/trac/report/3> and related at <http://tools.ietf.org/wg/httpbis/trac/report/3> and related
documents (including fancy diffs) can be found at documents (including fancy diffs) can be found at
<http://tools.ietf.org/wg/httpbis/>. <http://tools.ietf.org/wg/httpbis/>.
The changes in this draft are summarized in Appendix C.11. The changes in this draft are summarized in Appendix C.12.
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 January 13, 2011. This Internet-Draft will expire on February 5, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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1.2. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 6 1.2. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 6
1.2.1. Core Rules . . . . . . . . . . . . . . . . . . . . . . 7 1.2.1. Core Rules . . . . . . . . . . . . . . . . . . . . . . 7
1.2.2. ABNF Rules defined in other Parts of the 1.2.2. ABNF Rules defined in other Parts of the
Specification . . . . . . . . . . . . . . . . . . . . 7 Specification . . . . . . . . . . . . . . . . . . . . 7
2. Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 2. Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
2.1. Method Registry . . . . . . . . . . . . . . . . . . . . . 8 2.1. Method Registry . . . . . . . . . . . . . . . . . . . . . 8
3. Request Header Fields . . . . . . . . . . . . . . . . . . . . 9 3. Request Header Fields . . . . . . . . . . . . . . . . . . . . 9
4. Status Code and Reason Phrase . . . . . . . . . . . . . . . . 10 4. Status Code and Reason Phrase . . . . . . . . . . . . . . . . 10
4.1. Status Code Registry . . . . . . . . . . . . . . . . . . . 12 4.1. Status Code Registry . . . . . . . . . . . . . . . . . . . 12
5. Response Header Fields . . . . . . . . . . . . . . . . . . . . 12 5. Response Header Fields . . . . . . . . . . . . . . . . . . . . 12
6. Entity . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 6. Representation . . . . . . . . . . . . . . . . . . . . . . . . 13
6.1. Identifying the Resource Associated with a 6.1. Identifying the Resource Associated with a
Representation . . . . . . . . . . . . . . . . . . . . . . 13 Representation . . . . . . . . . . . . . . . . . . . . . . 13
7. Method Definitions . . . . . . . . . . . . . . . . . . . . . . 14 7. Method Definitions . . . . . . . . . . . . . . . . . . . . . . 14
7.1. Safe and Idempotent Methods . . . . . . . . . . . . . . . 14 7.1. Safe and Idempotent Methods . . . . . . . . . . . . . . . 14
7.1.1. Safe Methods . . . . . . . . . . . . . . . . . . . . . 14 7.1.1. Safe Methods . . . . . . . . . . . . . . . . . . . . . 14
7.1.2. Idempotent Methods . . . . . . . . . . . . . . . . . . 14 7.1.2. Idempotent Methods . . . . . . . . . . . . . . . . . . 14
7.2. OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . 14 7.2. OPTIONS . . . . . . . . . . . . . . . . . . . . . . . . . 15
7.3. GET . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7.3. GET . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.4. HEAD . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 7.4. HEAD . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
7.5. POST . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 7.5. POST . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
7.6. PUT . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 7.6. PUT . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
7.7. DELETE . . . . . . . . . . . . . . . . . . . . . . . . . . 19 7.7. DELETE . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.8. TRACE . . . . . . . . . . . . . . . . . . . . . . . . . . 19 7.8. TRACE . . . . . . . . . . . . . . . . . . . . . . . . . . 19
7.9. CONNECT . . . . . . . . . . . . . . . . . . . . . . . . . 20 7.9. CONNECT . . . . . . . . . . . . . . . . . . . . . . . . . 20
8. Status Code Definitions . . . . . . . . . . . . . . . . . . . 20 8. Status Code Definitions . . . . . . . . . . . . . . . . . . . 20
8.1. Informational 1xx . . . . . . . . . . . . . . . . . . . . 20 8.1. Informational 1xx . . . . . . . . . . . . . . . . . . . . 20
8.1.1. 100 Continue . . . . . . . . . . . . . . . . . . . . . 20 8.1.1. 100 Continue . . . . . . . . . . . . . . . . . . . . . 20
8.1.2. 101 Switching Protocols . . . . . . . . . . . . . . . 20 8.1.2. 101 Switching Protocols . . . . . . . . . . . . . . . 21
8.2. Successful 2xx . . . . . . . . . . . . . . . . . . . . . . 21 8.2. Successful 2xx . . . . . . . . . . . . . . . . . . . . . . 21
8.2.1. 200 OK . . . . . . . . . . . . . . . . . . . . . . . . 21 8.2.1. 200 OK . . . . . . . . . . . . . . . . . . . . . . . . 21
8.2.2. 201 Created . . . . . . . . . . . . . . . . . . . . . 21 8.2.2. 201 Created . . . . . . . . . . . . . . . . . . . . . 21
8.2.3. 202 Accepted . . . . . . . . . . . . . . . . . . . . . 22 8.2.3. 202 Accepted . . . . . . . . . . . . . . . . . . . . . 22
8.2.4. 203 Non-Authoritative Information . . . . . . . . . . 22 8.2.4. 203 Non-Authoritative Information . . . . . . . . . . 22
8.2.5. 204 No Content . . . . . . . . . . . . . . . . . . . . 22 8.2.5. 204 No Content . . . . . . . . . . . . . . . . . . . . 22
8.2.6. 205 Reset Content . . . . . . . . . . . . . . . . . . 23 8.2.6. 205 Reset Content . . . . . . . . . . . . . . . . . . 23
8.2.7. 206 Partial Content . . . . . . . . . . . . . . . . . 23 8.2.7. 206 Partial Content . . . . . . . . . . . . . . . . . 23
8.3. Redirection 3xx . . . . . . . . . . . . . . . . . . . . . 23 8.3. Redirection 3xx . . . . . . . . . . . . . . . . . . . . . 23
8.3.1. 300 Multiple Choices . . . . . . . . . . . . . . . . . 23 8.3.1. 300 Multiple Choices . . . . . . . . . . . . . . . . . 24
8.3.2. 301 Moved Permanently . . . . . . . . . . . . . . . . 24 8.3.2. 301 Moved Permanently . . . . . . . . . . . . . . . . 24
8.3.3. 302 Found . . . . . . . . . . . . . . . . . . . . . . 24 8.3.3. 302 Found . . . . . . . . . . . . . . . . . . . . . . 25
8.3.4. 303 See Other . . . . . . . . . . . . . . . . . . . . 25 8.3.4. 303 See Other . . . . . . . . . . . . . . . . . . . . 25
8.3.5. 304 Not Modified . . . . . . . . . . . . . . . . . . . 25 8.3.5. 304 Not Modified . . . . . . . . . . . . . . . . . . . 26
8.3.6. 305 Use Proxy . . . . . . . . . . . . . . . . . . . . 26 8.3.6. 305 Use Proxy . . . . . . . . . . . . . . . . . . . . 26
8.3.7. 306 (Unused) . . . . . . . . . . . . . . . . . . . . . 26 8.3.7. 306 (Unused) . . . . . . . . . . . . . . . . . . . . . 26
8.3.8. 307 Temporary Redirect . . . . . . . . . . . . . . . . 26 8.3.8. 307 Temporary Redirect . . . . . . . . . . . . . . . . 26
8.4. Client Error 4xx . . . . . . . . . . . . . . . . . . . . . 26 8.4. Client Error 4xx . . . . . . . . . . . . . . . . . . . . . 27
8.4.1. 400 Bad Request . . . . . . . . . . . . . . . . . . . 27 8.4.1. 400 Bad Request . . . . . . . . . . . . . . . . . . . 27
8.4.2. 401 Unauthorized . . . . . . . . . . . . . . . . . . . 27 8.4.2. 401 Unauthorized . . . . . . . . . . . . . . . . . . . 27
8.4.3. 402 Payment Required . . . . . . . . . . . . . . . . . 27 8.4.3. 402 Payment Required . . . . . . . . . . . . . . . . . 27
8.4.4. 403 Forbidden . . . . . . . . . . . . . . . . . . . . 27 8.4.4. 403 Forbidden . . . . . . . . . . . . . . . . . . . . 27
8.4.5. 404 Not Found . . . . . . . . . . . . . . . . . . . . 27 8.4.5. 404 Not Found . . . . . . . . . . . . . . . . . . . . 28
8.4.6. 405 Method Not Allowed . . . . . . . . . . . . . . . . 27 8.4.6. 405 Method Not Allowed . . . . . . . . . . . . . . . . 28
8.4.7. 406 Not Acceptable . . . . . . . . . . . . . . . . . . 28 8.4.7. 406 Not Acceptable . . . . . . . . . . . . . . . . . . 28
8.4.8. 407 Proxy Authentication Required . . . . . . . . . . 28 8.4.8. 407 Proxy Authentication Required . . . . . . . . . . 28
8.4.9. 408 Request Timeout . . . . . . . . . . . . . . . . . 28 8.4.9. 408 Request Timeout . . . . . . . . . . . . . . . . . 29
8.4.10. 409 Conflict . . . . . . . . . . . . . . . . . . . . . 28 8.4.10. 409 Conflict . . . . . . . . . . . . . . . . . . . . . 29
8.4.11. 410 Gone . . . . . . . . . . . . . . . . . . . . . . . 29 8.4.11. 410 Gone . . . . . . . . . . . . . . . . . . . . . . . 29
8.4.12. 411 Length Required . . . . . . . . . . . . . . . . . 29 8.4.12. 411 Length Required . . . . . . . . . . . . . . . . . 30
8.4.13. 412 Precondition Failed . . . . . . . . . . . . . . . 29 8.4.13. 412 Precondition Failed . . . . . . . . . . . . . . . 30
8.4.14. 413 Request Entity Too Large . . . . . . . . . . . . . 29 8.4.14. 413 Request Entity Too Large . . . . . . . . . . . . . 30
8.4.15. 414 URI Too Long . . . . . . . . . . . . . . . . . . . 30 8.4.15. 414 URI Too Long . . . . . . . . . . . . . . . . . . . 30
8.4.16. 415 Unsupported Media Type . . . . . . . . . . . . . . 30 8.4.16. 415 Unsupported Media Type . . . . . . . . . . . . . . 30
8.4.17. 416 Requested Range Not Satisfiable . . . . . . . . . 30 8.4.17. 416 Requested Range Not Satisfiable . . . . . . . . . 30
8.4.18. 417 Expectation Failed . . . . . . . . . . . . . . . . 30 8.4.18. 417 Expectation Failed . . . . . . . . . . . . . . . . 31
8.5. Server Error 5xx . . . . . . . . . . . . . . . . . . . . . 30 8.5. Server Error 5xx . . . . . . . . . . . . . . . . . . . . . 31
8.5.1. 500 Internal Server Error . . . . . . . . . . . . . . 31 8.5.1. 500 Internal Server Error . . . . . . . . . . . . . . 31
8.5.2. 501 Not Implemented . . . . . . . . . . . . . . . . . 31 8.5.2. 501 Not Implemented . . . . . . . . . . . . . . . . . 31
8.5.3. 502 Bad Gateway . . . . . . . . . . . . . . . . . . . 31 8.5.3. 502 Bad Gateway . . . . . . . . . . . . . . . . . . . 31
8.5.4. 503 Service Unavailable . . . . . . . . . . . . . . . 31 8.5.4. 503 Service Unavailable . . . . . . . . . . . . . . . 31
8.5.5. 504 Gateway Timeout . . . . . . . . . . . . . . . . . 31 8.5.5. 504 Gateway Timeout . . . . . . . . . . . . . . . . . 32
8.5.6. 505 HTTP Version Not Supported . . . . . . . . . . . . 31 8.5.6. 505 HTTP Version Not Supported . . . . . . . . . . . . 32
9. Header Field Definitions . . . . . . . . . . . . . . . . . . . 32 9. Header Field Definitions . . . . . . . . . . . . . . . . . . . 32
9.1. Allow . . . . . . . . . . . . . . . . . . . . . . . . . . 32 9.1. Allow . . . . . . . . . . . . . . . . . . . . . . . . . . 32
9.2. Expect . . . . . . . . . . . . . . . . . . . . . . . . . . 32 9.2. Expect . . . . . . . . . . . . . . . . . . . . . . . . . . 33
9.3. From . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 9.3. From . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
9.4. Location . . . . . . . . . . . . . . . . . . . . . . . . . 34 9.4. Location . . . . . . . . . . . . . . . . . . . . . . . . . 34
9.5. Max-Forwards . . . . . . . . . . . . . . . . . . . . . . . 35 9.5. Max-Forwards . . . . . . . . . . . . . . . . . . . . . . . 35
9.6. Referer . . . . . . . . . . . . . . . . . . . . . . . . . 35 9.6. Referer . . . . . . . . . . . . . . . . . . . . . . . . . 36
9.7. Retry-After . . . . . . . . . . . . . . . . . . . . . . . 36 9.7. Retry-After . . . . . . . . . . . . . . . . . . . . . . . 36
9.8. Server . . . . . . . . . . . . . . . . . . . . . . . . . . 37 9.8. Server . . . . . . . . . . . . . . . . . . . . . . . . . . 37
9.9. User-Agent . . . . . . . . . . . . . . . . . . . . . . . . 37 9.9. User-Agent . . . . . . . . . . . . . . . . . . . . . . . . 37
10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 38 10. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 38
10.1. Method Registry . . . . . . . . . . . . . . . . . . . . . 38 10.1. Method Registry . . . . . . . . . . . . . . . . . . . . . 38
10.2. Status Code Registry . . . . . . . . . . . . . . . . . . . 38 10.2. Status Code Registry . . . . . . . . . . . . . . . . . . . 38
10.3. Message Header Registration . . . . . . . . . . . . . . . 39 10.3. Header Field Registration . . . . . . . . . . . . . . . . 39
11. Security Considerations . . . . . . . . . . . . . . . . . . . 40 11. Security Considerations . . . . . . . . . . . . . . . . . . . 40
11.1. Transfer of Sensitive Information . . . . . . . . . . . . 40 11.1. Transfer of Sensitive Information . . . . . . . . . . . . 40
11.2. Encoding Sensitive Information in URIs . . . . . . . . . . 41 11.2. Encoding Sensitive Information in URIs . . . . . . . . . . 41
11.3. Location Headers and Spoofing . . . . . . . . . . . . . . 42 11.3. Location Headers and Spoofing . . . . . . . . . . . . . . 42
12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 42 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 42
13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 42 13. References . . . . . . . . . . . . . . . . . . . . . . . . . . 42
13.1. Normative References . . . . . . . . . . . . . . . . . . . 42 13.1. Normative References . . . . . . . . . . . . . . . . . . . 42
13.2. Informative References . . . . . . . . . . . . . . . . . . 43 13.2. Informative References . . . . . . . . . . . . . . . . . . 43
Appendix A. Compatibility with Previous Versions . . . . . . . . 43 Appendix A. Changes from RFC 2616 . . . . . . . . . . . . . . . . 43
A.1. Changes from RFC 2068 . . . . . . . . . . . . . . . . . . 43 Appendix B. Collected ABNF . . . . . . . . . . . . . . . . . . . 44
A.2. Changes from RFC 2616 . . . . . . . . . . . . . . . . . . 44
Appendix B. Collected ABNF . . . . . . . . . . . . . . . . . . . 45
Appendix C. Change Log (to be removed by RFC Editor before Appendix C. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 48 publication) . . . . . . . . . . . . . . . . . . . . 47
C.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 48
C.2. Since draft-ietf-httpbis-p2-semantics-00 . . . . . . . . . 48 C.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 47
C.3. Since draft-ietf-httpbis-p2-semantics-01 . . . . . . . . . 49 C.2. Since draft-ietf-httpbis-p2-semantics-00 . . . . . . . . . 47
C.4. Since draft-ietf-httpbis-p2-semantics-02 . . . . . . . . . 49 C.3. Since draft-ietf-httpbis-p2-semantics-01 . . . . . . . . . 47
C.5. Since draft-ietf-httpbis-p2-semantics-03 . . . . . . . . . 50 C.4. Since draft-ietf-httpbis-p2-semantics-02 . . . . . . . . . 48
C.6. Since draft-ietf-httpbis-p2-semantics-04 . . . . . . . . . 50 C.5. Since draft-ietf-httpbis-p2-semantics-03 . . . . . . . . . 49
C.7. Since draft-ietf-httpbis-p2-semantics-05 . . . . . . . . . 51 C.6. Since draft-ietf-httpbis-p2-semantics-04 . . . . . . . . . 49
C.8. Since draft-ietf-httpbis-p2-semantics-06 . . . . . . . . . 51 C.7. Since draft-ietf-httpbis-p2-semantics-05 . . . . . . . . . 49
C.9. Since draft-ietf-httpbis-p2-semantics-07 . . . . . . . . . 51 C.8. Since draft-ietf-httpbis-p2-semantics-06 . . . . . . . . . 50
C.10. Since draft-ietf-httpbis-p2-semantics-08 . . . . . . . . . 52 C.9. Since draft-ietf-httpbis-p2-semantics-07 . . . . . . . . . 50
C.11. Since draft-ietf-httpbis-p2-semantics-09 . . . . . . . . . 52 C.10. Since draft-ietf-httpbis-p2-semantics-08 . . . . . . . . . 51
C.11. Since draft-ietf-httpbis-p2-semantics-09 . . . . . . . . . 51
C.12. Since draft-ietf-httpbis-p2-semantics-10 . . . . . . . . . 51
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
1. Introduction 1. Introduction
This document defines HTTP/1.1 request and response semantics. Each This document defines HTTP/1.1 request and response semantics. Each
HTTP message, as defined in [Part1], is in the form of either a HTTP message, as defined in [Part1], is in the form of either a
request or a response. An HTTP server listens on a connection for request or a response. An HTTP server listens on a connection for
HTTP requests and responds to each request, in the order received on HTTP requests and responds to each request, in the order received on
that connection, with one or more HTTP response messages. This that connection, with one or more HTTP response messages. This
document defines the commonly agreed upon semantics of the HTTP document defines the commonly agreed upon semantics of the HTTP
uniform interface, the intentions defined by each request method, and uniform interface, the intentions defined by each request method, and
the various response messages that might be expected as a result of the various response messages that might be expected as a result of
applying that method for the requested resource. applying that method to the target resource.
This document is currently disorganized in order to minimize the This document is currently disorganized in order to minimize the
changes between drafts and enable reviewers to see the smaller errata changes between drafts and enable reviewers to see the smaller errata
changes. The next draft will reorganize the sections to better changes. The next draft will reorganize the sections to better
reflect the content. In particular, the sections will be ordered reflect the content. In particular, the sections will be ordered
according to the typical processing of an HTTP request message (after according to the typical processing of an HTTP request message (after
message parsing): resource mapping, general header fields, methods, message parsing): resource mapping, general header fields, methods,
request modifiers, response status, and resource metadata. The request modifiers, response status, and resource metadata. The
current mess reflects how widely dispersed these topics and current mess reflects how widely dispersed these topics and
associated requirements had become in [RFC2616]. associated requirements had become in [RFC2616].
skipping to change at page 7, line 30 skipping to change at page 7, line 30
absolute-URI = <absolute-URI, defined in [Part1], Section 2.6> absolute-URI = <absolute-URI, defined in [Part1], Section 2.6>
comment = <comment, defined in [Part1], Section 3.2> comment = <comment, defined in [Part1], Section 3.2>
Host = <Host, defined in [Part1], Section 2.6> Host = <Host, defined in [Part1], Section 2.6>
HTTP-date = <HTTP-date, defined in [Part1], Section 6.1> HTTP-date = <HTTP-date, defined in [Part1], Section 6.1>
partial-URI = <partial-URI, defined in [Part1], Section 2.6> partial-URI = <partial-URI, defined in [Part1], Section 2.6>
product = <product, defined in [Part1], Section 6.3> product = <product, defined in [Part1], Section 6.3>
TE = <TE, defined in [Part1], Section 9.5> TE = <TE, defined in [Part1], Section 9.5>
URI-reference = <URI-reference, defined in [Part1], Section 2.6> URI-reference = <URI-reference, defined in [Part1], Section 2.6>
Accept = <Accept, defined in [Part3], Section 5.1> Accept = <Accept, defined in [Part3], Section 6.1>
Accept-Charset = Accept-Charset =
<Accept-Charset, defined in [Part3], Section 5.2> <Accept-Charset, defined in [Part3], Section 6.2>
Accept-Encoding = Accept-Encoding =
<Accept-Encoding, defined in [Part3], Section 5.3> <Accept-Encoding, defined in [Part3], Section 6.3>
Accept-Language = Accept-Language =
<Accept-Language, defined in [Part3], Section 5.4> <Accept-Language, defined in [Part3], Section 6.4>
ETag = <ETag, defined in [Part4], Section 6.1> ETag = <ETag, defined in [Part4], Section 6.1>
If-Match = <If-Match, defined in [Part4], Section 6.2> If-Match = <If-Match, defined in [Part4], Section 6.2>
If-Modified-Since = If-Modified-Since =
<If-Modified-Since, defined in [Part4], Section 6.3> <If-Modified-Since, defined in [Part4], Section 6.3>
If-None-Match = <If-None-Match, defined in [Part4], Section 6.4> If-None-Match = <If-None-Match, defined in [Part4], Section 6.4>
If-Unmodified-Since = If-Unmodified-Since =
<If-Unmodified-Since, defined in [Part4], Section 6.5> <If-Unmodified-Since, defined in [Part4], Section 6.5>
Accept-Ranges = <Accept-Ranges, defined in [Part5], Section 5.1> Accept-Ranges = <Accept-Ranges, defined in [Part5], Section 5.1>
skipping to change at page 8, line 17 skipping to change at page 8, line 17
Authorization = <Authorization, defined in [Part7], Section 3.1> Authorization = <Authorization, defined in [Part7], Section 3.1>
Proxy-Authenticate = Proxy-Authenticate =
<Proxy-Authenticate, defined in [Part7], Section 3.2> <Proxy-Authenticate, defined in [Part7], Section 3.2>
Proxy-Authorization = Proxy-Authorization =
<Proxy-Authorization, defined in [Part7], Section 3.3> <Proxy-Authorization, defined in [Part7], Section 3.3>
WWW-Authenticate = WWW-Authenticate =
<WWW-Authenticate, defined in [Part7], Section 3.4> <WWW-Authenticate, defined in [Part7], Section 3.4>
2. Method 2. Method
The Method token indicates the method to be performed on the resource The Method token indicates the method to be performed on the target
identified by the Effective Request URI (Section 4.3 of [Part1]). resource (Section 4.3 of [Part1]). The method is case-sensitive.
The method is case-sensitive.
Method = %x4F.50.54.49.4F.4E.53 ; "OPTIONS", Section 7.2 Method = %x4F.50.54.49.4F.4E.53 ; "OPTIONS", Section 7.2
/ %x47.45.54 ; "GET", Section 7.3 / %x47.45.54 ; "GET", Section 7.3
/ %x48.45.41.44 ; "HEAD", Section 7.4 / %x48.45.41.44 ; "HEAD", Section 7.4
/ %x50.4F.53.54 ; "POST", Section 7.5 / %x50.4F.53.54 ; "POST", Section 7.5
/ %x50.55.54 ; "PUT", Section 7.6 / %x50.55.54 ; "PUT", Section 7.6
/ %x44.45.4C.45.54.45 ; "DELETE", Section 7.7 / %x44.45.4C.45.54.45 ; "DELETE", Section 7.7
/ %x54.52.41.43.45 ; "TRACE", Section 7.8 / %x54.52.41.43.45 ; "TRACE", Section 7.8
/ %x43.4F.4E.4E.45.43.54 ; "CONNECT", Section 7.9 / %x43.4F.4E.4E.45.43.54 ; "CONNECT", Section 7.9
/ extension-method / extension-method
extension-method = token extension-method = token
The list of methods allowed by a resource can be specified in an The list of methods allowed by a resource can be specified in an
Allow header field (Section 9.1). The return code of the response Allow header field (Section 9.1). The status code of the response
always notifies the client whether a method is currently allowed on a always notifies the client whether a method is currently allowed on a
resource, since the set of allowed methods can change dynamically. resource, since the set of allowed methods can change dynamically.
An origin server SHOULD return the status code 405 (Method Not An origin server SHOULD respond with the status code 405 (Method Not
Allowed) if the method is known by the origin server but not allowed Allowed) if the method is known by the origin server but not allowed
for the requested resource, and 501 (Not Implemented) if the method for the resource, and 501 (Not Implemented) if the method is
is unrecognized or not implemented by the origin server. The methods unrecognized or not implemented by the origin server. The methods
GET and HEAD MUST be supported by all general-purpose servers. All GET and HEAD MUST be supported by all general-purpose servers. All
other methods are OPTIONAL; however, if the above methods are other methods are OPTIONAL; however, if the above methods are
implemented, they MUST be implemented with the same semantics as implemented, they MUST be implemented with the same semantics as
those specified in Section 7. those specified in Section 7.
2.1. Method Registry 2.1. Method Registry
The HTTP Method Registry defines the name space for the Method token The HTTP Method Registry defines the name space for the Method token
in the Request line of an HTTP request. in the Request line of an HTTP request.
skipping to change at page 9, line 25 skipping to change at page 9, line 25
<http://www.iana.org/assignments/http-methods>. <http://www.iana.org/assignments/http-methods>.
3. Request Header Fields 3. Request Header Fields
The request-header fields allow the client to pass additional The request-header fields allow the client to pass additional
information about the request, and about the client itself, to the information about the request, and about the client itself, to the
server. These fields act as request modifiers, with semantics server. These fields act as request modifiers, with semantics
equivalent to the parameters on a programming language method equivalent to the parameters on a programming language method
invocation. invocation.
request-header = Accept ; [Part3], Section 5.1 request-header = Accept ; [Part3], Section 6.1
/ Accept-Charset ; [Part3], Section 5.2 / Accept-Charset ; [Part3], Section 6.2
/ Accept-Encoding ; [Part3], Section 5.3 / Accept-Encoding ; [Part3], Section 6.3
/ Accept-Language ; [Part3], Section 5.4 / Accept-Language ; [Part3], Section 6.4
/ Authorization ; [Part7], Section 3.1 / Authorization ; [Part7], Section 3.1
/ Expect ; Section 9.2 / Expect ; Section 9.2
/ From ; Section 9.3 / From ; Section 9.3
/ Host ; [Part1], Section 9.4 / Host ; [Part1], Section 9.4
/ If-Match ; [Part4], Section 6.2 / If-Match ; [Part4], Section 6.2
/ If-Modified-Since ; [Part4], Section 6.3 / If-Modified-Since ; [Part4], Section 6.3
/ If-None-Match ; [Part4], Section 6.4 / If-None-Match ; [Part4], Section 6.4
/ If-Range ; [Part5], Section 5.3 / If-Range ; [Part5], Section 5.3
/ If-Unmodified-Since ; [Part4], Section 6.5 / If-Unmodified-Since ; [Part4], Section 6.5
/ Max-Forwards ; Section 9.5 / Max-Forwards ; Section 9.5
/ Proxy-Authorization ; [Part7], Section 3.3 / Proxy-Authorization ; [Part7], Section 3.3
/ Range ; [Part5], Section 5.4 / Range ; [Part5], Section 5.4
/ Referer ; Section 9.6 / Referer ; Section 9.6
/ TE ; [Part1], Section 9.5 / TE ; [Part1], Section 9.5
/ User-Agent ; Section 9.9 / User-Agent ; Section 9.9
Request-header field names can be extended reliably only in Request-header field names can be extended reliably only in
combination with a change in the protocol version. However, new or combination with a change in the protocol version. However, new or
experimental header fields MAY be given the semantics of request- experimental header fields MAY be given the semantics of request-
header fields if all parties in the communication recognize them to header fields if all parties in the communication recognize them to
be request-header fields. Unrecognized header fields are treated as be request-header fields.
entity-header fields.
4. Status Code and Reason Phrase 4. Status Code and Reason Phrase
The Status-Code element is a 3-digit integer result code of the The Status-Code element is a 3-digit integer result code of the
attempt to understand and satisfy the request. The status codes attempt to understand and satisfy the request. The status codes
listed below are defined in Section 8, Section 3 of [Part4], Section listed below are defined in Section 8, Section 3 of [Part4], Section
3 of [Part5], and Section 2 of [Part7]. 3 of [Part5], and Section 2 of [Part7].
The Reason-Phrase is intended to give a short textual description of The Reason-Phrase is intended to give a short textual description of
the Status-Code. The Status-Code is intended for use by automata and the Status-Code. The Status-Code is intended for use by automata and
skipping to change at page 12, line 12 skipping to change at page 12, line 12
HTTP status codes are extensible. HTTP applications are not required HTTP status codes are extensible. HTTP applications are not required
to understand the meaning of all registered status codes, though such to understand the meaning of all registered status codes, though such
understanding is obviously desirable. However, applications MUST understanding is obviously desirable. However, applications MUST
understand the class of any status code, as indicated by the first understand the class of any status code, as indicated by the first
digit, and treat any unrecognized response as being equivalent to the digit, and treat any unrecognized response as being equivalent to the
x00 status code of that class, with the exception that an x00 status code of that class, with the exception that an
unrecognized response MUST NOT be cached. For example, if an unrecognized response MUST NOT be cached. For example, if an
unrecognized status code of 431 is received by the client, it can unrecognized status code of 431 is received by the client, it can
safely assume that there was something wrong with its request and safely assume that there was something wrong with its request and
treat the response as if it had received a 400 status code. In such treat the response as if it had received a 400 status code. In such
cases, user agents SHOULD present to the user the entity returned cases, user agents SHOULD present to the user the representation
with the response, since that entity is likely to include human- enclosed with the response, since that representation is likely to
readable information which will explain the unusual status. include human-readable information which will explain the unusual
status.
4.1. Status Code Registry 4.1. Status Code Registry
The HTTP Status Code Registry defines the name space for the Status- The HTTP Status Code Registry defines the name space for the Status-
Code token in the Status line of an HTTP response. Code token in the Status-Line of an HTTP response.
Values to be added to this name space are subject to IETF review Values to be added to this name space are subject to IETF review
([RFC5226], Section 4.1). ([RFC5226], Section 4.1).
The registry itself is maintained at The registry itself is maintained at
<http://www.iana.org/assignments/http-status-codes>. <http://www.iana.org/assignments/http-status-codes>.
5. Response Header Fields 5. Response Header Fields
The response-header fields allow the server to pass additional The response-header fields allow the server to pass additional
information about the response which cannot be placed in the Status- information about the response which cannot be placed in the Status-
Line. These header fields give information about the server and Line. These header fields give information about the server and
about further access to the resource identified by the Effective about further access to the target resource (Section 4.3 of [Part1]).
Request URI (Section 4.3 of [Part1]).
response-header = Accept-Ranges ; [Part5], Section 5.1 response-header = Accept-Ranges ; [Part5], Section 5.1
/ Age ; [Part6], Section 3.1 / Age ; [Part6], Section 3.1
/ Allow ; Section 9.1 / Allow ; Section 9.1
/ ETag ; [Part4], Section 6.1 / ETag ; [Part4], Section 6.1
/ Location ; Section 9.4 / Location ; Section 9.4
/ Proxy-Authenticate ; [Part7], Section 3.2 / Proxy-Authenticate ; [Part7], Section 3.2
/ Retry-After ; Section 9.7 / Retry-After ; Section 9.7
/ Server ; Section 9.8 / Server ; Section 9.8
/ Vary ; [Part6], Section 3.5 / Vary ; [Part6], Section 3.5
/ WWW-Authenticate ; [Part7], Section 3.4 / WWW-Authenticate ; [Part7], Section 3.4
Response-header field names can be extended reliably only in Response-header field names can be extended reliably only in
combination with a change in the protocol version. However, new or combination with a change in the protocol version. However, new or
experimental header fields MAY be given the semantics of response- experimental header fields MAY be given the semantics of response-
header fields if all parties in the communication recognize them to header fields if all parties in the communication recognize them to
be response-header fields. Unrecognized header fields are treated as be response-header fields.
entity-header fields.
6. Entity 6. Representation
Request and Response messages MAY transfer an entity if not otherwise Request and Response messages MAY transfer a representation if not
restricted by the request method or response status code. An entity otherwise restricted by the request method or response status code.
consists of entity-header fields and an entity-body, although some A representation consists of metadata (representation header fields)
responses will only include the entity-headers. HTTP entity-body and and data (representation body). When a complete or partial
entity-header fields are defined in [Part3]. representation is enclosed in an HTTP message, it is referred to as
the payload of the message. HTTP representations are defined in
[Part3].
An entity-body is only present in a message when a message-body is A representation body is only present in a message when a message-
present, as described in Section 3.3 of [Part1]. The entity-body is body is present, as described in Section 3.3 of [Part1]. The
obtained from the message-body by decoding any Transfer-Encoding that representation body is obtained from the message-body by decoding any
might have been applied to ensure safe and proper transfer of the Transfer-Encoding that might have been applied to ensure safe and
message. proper transfer of the message.
6.1. Identifying the Resource Associated with a Representation 6.1. Identifying the Resource Associated with a Representation
It is sometimes necessary to determine the identity of the resource It is sometimes necessary to determine an identifier for the resource
associated with a representation. associated with a representation.
An HTTP request representation, when present, is always associated An HTTP request representation, when present, is always associated
with an anonymous (i.e., unidentified) resource. with an anonymous (i.e., unidentified) resource.
In the common case, an HTTP response is a representation of the In the common case, an HTTP response is a representation of the
resource located at the Effective Request URI (see Section 4.3 of target resource (see Section 4.3 of [Part1]). However, this is not
[Part1]). However, this is not always the case. To determine the always the case. To determine the URI of the resource a response is
URI of the resource a response is associated with, the following associated with, the following rules are used (with the first
rules are used (with the first applicable one being selected): applicable one being selected):
1. If the response status code is 200 or 203 and the request method 1. If the response status code is 200 or 203 and the request method
was GET, the response is a representation of the resource at the was GET, the response payload is a representation of the target
Effective Request URI. resource.
2. If the response status is 204, 206, or 304 and the request method 2. If the response status code is 204, 206, or 304 and the request
was GET or HEAD, the response is a partial representation of the method was GET or HEAD, the response payload is a partial
resource at the Effective Request URI (see Section 2.8 of representation of the target (see Section 2.8 of [Part6]).
[Part6]).
3. If the response has a Content-Location header, and that URI is 3. If the response has a Content-Location header, and that URI is
the same as the Effective Request URI, the response is a the same as the effective request URI, the response payload is a
representation of the resource at the Effective Request URI. representation of the target resource.
4. If the response has a Content-Location header, and that URI is 4. If the response has a Content-Location header, and that URI is
not the same as the Effective Request URI, the response asserts not the same as the effective request URI, then the response
that it is a representation of the resource at the Content- asserts that its payload is a representation of the resource
Location URI (but it may not be). identified by the Content-Location URI. However, such an
assertion cannot be trusted unless it can be verified by other
means (not defined by HTTP).
5. Otherwise, the response is a representation of an anonymous 5. Otherwise, the response is a representation of an anonymous
(i.e., unidentified) resource. (i.e., unidentified) resource.
[[TODO-req-uri: The comparison function is going to have to be [[TODO-req-uri: The comparison function is going to have to be
defined somewhere, because we already need to compare URIs for things defined somewhere, because we already need to compare URIs for things
like cache invalidation.]] like cache invalidation.]]
7. Method Definitions 7. Method Definitions
The set of common methods for HTTP/1.1 is defined below. Although The set of common methods for HTTP/1.1 is defined below. Although
this set can be expanded, additional methods cannot be assumed to this set can be expanded, additional methods cannot be assumed to
share the same semantics for separately extended clients and servers. share the same semantics for separately extended clients and servers.
7.1. Safe and Idempotent Methods 7.1. Safe and Idempotent Methods
7.1.1. Safe Methods 7.1.1. Safe Methods
Implementors should be aware that the software represents the user in Implementors need to be aware that the software represents the user
their interactions over the Internet, and should be careful to allow in their interactions over the Internet, and need to allow the user
the user to be aware of any actions they might take which may have an to be aware of any actions they take which might have an unexpected
unexpected significance to themselves or others. significance to themselves or others.
In particular, the convention has been established that the GET, In particular, the convention has been established that the GET,
HEAD, OPTIONS, and TRACE methods SHOULD NOT have the significance of HEAD, OPTIONS, and TRACE methods SHOULD NOT have the significance of
taking an action other than retrieval. These methods ought to be taking an action other than retrieval. These methods ought to be
considered "safe". This allows user agents to represent other considered "safe". This allows user agents to represent other
methods, such as POST, PUT and DELETE, in a special way, so that the methods, such as POST, PUT and DELETE, in a special way, so that the
user is made aware of the fact that a possibly unsafe action is being user is made aware of the fact that a possibly unsafe action is being
requested. requested.
Naturally, it is not possible to ensure that the server does not Naturally, it is not possible to ensure that the server does not
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identical requests is the same as for a single request. The methods identical requests is the same as for a single request. The methods
PUT, DELETE, and all safe methods are idempotent. It is important to PUT, DELETE, and all safe methods are idempotent. It is important to
note that idempotence refers only to changes requested by the client: note that idempotence refers only to changes requested by the client:
a server is free to change its state due to multiple requests for the a server is free to change its state due to multiple requests for the
purpose of tracking those requests, versioning of results, etc. purpose of tracking those requests, versioning of results, etc.
7.2. OPTIONS 7.2. OPTIONS
The OPTIONS method represents a request for information about the The OPTIONS method represents a request for information about the
communication options available on the request/response chain communication options available on the request/response chain
identified by the Effective Request URI. This method allows the identified by the effective request URI. This method allows the
client to determine the options and/or requirements associated with a client to determine the options and/or requirements associated with a
resource, or the capabilities of a server, without implying a resource, or the capabilities of a server, without implying a
resource action or initiating a resource retrieval. resource action or initiating a resource retrieval.
Responses to this method are not cacheable. Responses to this method are not cacheable.
If the OPTIONS request includes an entity-body (as indicated by the If the OPTIONS request includes a message-body (as indicated by the
presence of Content-Length or Transfer-Encoding), then the media type presence of Content-Length or Transfer-Encoding), then the media type
MUST be indicated by a Content-Type field. Although this MUST be indicated by a Content-Type field. Although this
specification does not define any use for such a body, future specification does not define any use for such a body, future
extensions to HTTP might use the OPTIONS body to make more detailed extensions to HTTP might use the OPTIONS body to make more detailed
queries on the server. queries on the server.
If the request-target is an asterisk ("*"), the OPTIONS request is If the request-target is an asterisk ("*"), the OPTIONS request is
intended to apply to the server in general rather than to a specific intended to apply to the server in general rather than to a specific
resource. Since a server's communication options typically depend on resource. Since a server's communication options typically depend on
the resource, the "*" request is only useful as a "ping" or "no-op" the resource, the "*" request is only useful as a "ping" or "no-op"
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resource (e.g., Allow), possibly including extensions not defined by resource (e.g., Allow), possibly including extensions not defined by
this specification. The response body, if any, SHOULD also include this specification. The response body, if any, SHOULD also include
information about the communication options. The format for such a information about the communication options. The format for such a
body is not defined by this specification, but might be defined by body is not defined by this specification, but might be defined by
future extensions to HTTP. Content negotiation MAY be used to select future extensions to HTTP. Content negotiation MAY be used to select
the appropriate response format. If no response body is included, the appropriate response format. If no response body is included,
the response MUST include a Content-Length field with a field-value the response MUST include a Content-Length field with a field-value
of "0". of "0".
The Max-Forwards request-header field MAY be used to target a The Max-Forwards request-header field MAY be used to target a
specific proxy in the request chain. When a proxy receives an specific proxy in the request chain (see Section 9.5). If no Max-
OPTIONS request on an absolute-URI for which request forwarding is Forwards field is present in the request, then the forwarded request
permitted, the proxy MUST check for a Max-Forwards field. If the MUST NOT include a Max-Forwards field.
Max-Forwards field-value is zero ("0"), the proxy MUST NOT forward
the message; instead, the proxy SHOULD respond with its own
communication options. If the Max-Forwards field-value is an integer
greater than zero, the proxy MUST decrement the field-value when it
forwards the request. If no Max-Forwards field is present in the
request, then the forwarded request MUST NOT include a Max-Forwards
field.
7.3. GET 7.3. GET
The GET method means retrieve whatever information (in the form of an The GET method means retrieve whatever information (in the form of a
entity) currently corresponds to the resource identified by the representation) currently corresponds to the target resource.
Effective Request URI.
If the Effective Request URI identifies a data-producing process, it If the target resource is a data-producing process, it is the
is the produced data which shall be returned as the entity in the produced data which shall be returned as the representation in the
response and not the source text of the process, unless that text response and not the source text of the process, unless that text
happens to be the output of the process. happens to be the output of the process.
The semantics of the GET method change to a "conditional GET" if the The semantics of the GET method change to a "conditional GET" if the
request message includes an If-Modified-Since, If-Unmodified-Since, request message includes an If-Modified-Since, If-Unmodified-Since,
If-Match, If-None-Match, or If-Range header field. A conditional GET If-Match, If-None-Match, or If-Range header field. A conditional GET
method requests that the entity be transferred only under the method requests that the representation be transferred only under the
circumstances described by the conditional header field(s). The circumstances described by the conditional header field(s). The
conditional GET method is intended to reduce unnecessary network conditional GET method is intended to reduce unnecessary network
usage by allowing cached entities to be refreshed without requiring usage by allowing cached representations to be refreshed without
multiple requests or transferring data already held by the client. requiring multiple requests or transferring data already held by the
client.
The semantics of the GET method change to a "partial GET" if the The semantics of the GET method change to a "partial GET" if the
request message includes a Range header field. A partial GET request message includes a Range header field. A partial GET
requests that only part of the entity be transferred, as described in requests that only part of the representation be transferred, as
Section 5.4 of [Part5]. The partial GET method is intended to reduce described in Section 5.4 of [Part5]. The partial GET method is
unnecessary network usage by allowing partially-retrieved entities to intended to reduce unnecessary network usage by allowing partially-
be completed without transferring data already held by the client. retrieved representations to be completed without transferring data
already held by the client.
The response to a GET request is cacheable if and only if it meets The response to a GET request is cacheable and MAY be used to satisfy
the requirements for HTTP caching described in [Part6]. subsequent GET and HEAD requests (see [Part6]).
See Section 11.2 for security considerations when used for forms. See Section 11.2 for security considerations when used for forms.
7.4. HEAD 7.4. HEAD
The HEAD method is identical to GET except that the server MUST NOT The HEAD method is identical to GET except that the server MUST NOT
return a message-body in the response. The metainformation contained return a message-body in the response. The metadata contained in the
in the HTTP headers in response to a HEAD request SHOULD be identical HTTP headers in response to a HEAD request SHOULD be identical to the
to the information sent in response to a GET request. This method information sent in response to a GET request. This method can be
can be used for obtaining metainformation about the entity implied by used for obtaining metadata about the representation implied by the
the request without transferring the entity-body itself. This method request without transferring the representation body. This method is
is often used for testing hypertext links for validity, often used for testing hypertext links for validity, accessibility,
accessibility, and recent modification. and recent modification.
The response to a HEAD request MAY be cacheable in the sense that the The response to a HEAD request is cacheable and MAY be used to
information contained in the response MAY be used to update a satisfy a subsequent HEAD request; see [Part6]. It also MAY be used
previously cached entity from that resource. If the new field values to update a previously cached representation from that resource; if
indicate that the cached entity differs from the current entity (as the new field values indicate that the cached representation differs
would be indicated by a change in Content-Length, Content-MD5, ETag from the current representation (as would be indicated by a change in
or Last-Modified), then the cache MUST treat the cache entry as Content-Length, Content-MD5, ETag or Last-Modified), then the cache
stale. MUST treat the cache entry as stale.
7.5. POST 7.5. POST
The POST method is used to request that the origin server accept the The POST method is used to request that the origin server accept the
entity enclosed in the request as data to be processed by the representation enclosed in the request as data to be processed by the
resource identified by the Effective Request URI. POST is designed target resource. POST is designed to allow a uniform method to cover
to allow a uniform method to cover the following functions: the following functions:
o Annotation of existing resources; o Annotation of existing resources;
o Posting a message to a bulletin board, newsgroup, mailing list, or o Posting a message to a bulletin board, newsgroup, mailing list, or
similar group of articles; similar group of articles;
o Providing a block of data, such as the result of submitting a o Providing a block of data, such as the result of submitting a
form, to a data-handling process; form, to a data-handling process;
o Extending a database through an append operation. o Extending a database through an append operation.
The actual function performed by the POST method is determined by the The actual function performed by the POST method is determined by the
server and is usually dependent on the Effective Request URI. server and is usually dependent on the effective request URI.
The action performed by the POST method might not result in a The action performed by the POST method might not result in a
resource that can be identified by a URI. In this case, either 200 resource that can be identified by a URI. In this case, either 200
(OK) or 204 (No Content) is the appropriate response status, (OK) or 204 (No Content) is the appropriate response status code,
depending on whether or not the response includes an entity that depending on whether or not the response includes a representation
describes the result. that describes the result.
If a resource has been created on the origin server, the response If a resource has been created on the origin server, the response
SHOULD be 201 (Created) and contain an entity which describes the SHOULD be 201 (Created) and contain a representation which describes
status of the request and refers to the new resource, and a Location the status of the request and refers to the new resource, and a
header (see Section 9.4). Location header (see Section 9.4).
Responses to this method are not cacheable, unless the response Responses to POST requests are only cacheable when they include
includes appropriate Cache-Control or Expires header fields. explicit freshness information (see Section 2.3.1 of [Part6]). A
However, the 303 (See Other) response can be used to direct the user cached POST response with a Content-Location header (see Section 6.7
agent to retrieve a cacheable resource. of [Part3]) whose value is the effective Request URI MAY be used to
satisfy subsequent GET and HEAD requests.
Note that POST caching is not widely implemented. However, the 303
(See Other) response can be used to direct the user agent to retrieve
a cacheable resource.
7.6. PUT 7.6. PUT
The PUT method requests that the enclosed entity be stored at the The PUT method requests that the enclosed representation be stored at
Effective Request URI. If the Effective Request URI refers to an the effective request URI. If the effective request URI refers to an
already existing resource, the enclosed entity SHOULD be considered already existing resource, the enclosed representation SHOULD be
as a modified version of the one residing on the origin server. considered a modified version of the one residing on the origin
Otherwise, if the Effective Request URI does not point to an existing server. Otherwise, if the effective request URI does not point to an
resource, and that URI is capable of being defined as a new resource existing resource, and that URI is capable of being defined as a new
by the requesting user agent, the origin server can create the resource by the requesting user agent, the origin server can create
resource with that URI. the resource with that URI.
If a new resource is created at the Effective Request URI, the origin If a new resource is created at the effective request URI, the origin
server MUST inform the user agent via the 201 (Created) response. If server MUST inform the user agent via the 201 (Created) response. If
an existing resource is modified, either the 200 (OK) or 204 (No an existing resource is modified, either the 200 (OK) or 204 (No
Content) response codes SHOULD be sent to indicate successful Content) response codes SHOULD be sent to indicate successful
completion of the request. completion of the request.
If the resource could not be created or modified with the Effective If the target resource could not be created or modified, an
Request URI, an appropriate error response SHOULD be given that appropriate error response SHOULD be given that reflects the nature
reflects the nature of the problem. The recipient of the entity MUST of the problem. The recipient of the representation MUST NOT ignore
NOT ignore any Content-* headers (headers starting with the prefix any Content-* headers (headers starting with the prefix "Content-")
"Content-") that it does not understand or implement and MUST return that it does not understand or implement and MUST return a 501 (Not
a 501 (Not Implemented) response in such cases. Implemented) response in such cases.
If the request passes through a cache and the Effective Request URI If the request passes through a cache that has one or more stored
identifies one or more currently cached entities, those entries responses for the effective request URI, those stored responses
SHOULD be treated as stale. Responses to this method are not SHOULD be marked as stale if the response to the PUT request has a
cacheable. success status code. Responses to the PUT method are not cacheable.
The fundamental difference between the POST and PUT requests is The fundamental difference between the POST and PUT requests is
reflected in the different meaning of the Effective Request URI. The reflected in the different meaning of the effective request URI. The
URI in a POST request identifies the resource that will handle the URI in a POST request identifies the resource that will handle the
enclosed entity. That resource might be a data-accepting process, a enclosed representation. That resource might be a data-accepting
gateway to some other protocol, or a separate entity that accepts process, a gateway to some other protocol, or a document that accepts
annotations. In contrast, the URI in a PUT request identifies the annotations. In contrast, the URI in a PUT request identifies the
entity enclosed with the request -- the user agent knows what URI is resource for which enclosed representation is a new or replacement
intended and the server MUST NOT attempt to apply the request to some value; the user agent knows what URI is intended and the server MUST
other resource. If the server desires that the request be applied to NOT attempt to apply the request to some other resource. If the
a different URI, it MUST send a 301 (Moved Permanently) response; the server desires that the request be applied to a different URI, it
user agent MAY then make its own decision regarding whether or not to MUST send a 301 (Moved Permanently) response; the user agent MAY then
redirect the request. make its own decision regarding whether or not to redirect the
request.
A single resource MAY be identified by many different URIs. For A single resource MAY be identified by many different URIs. For
example, an article might have a URI for identifying "the current example, an article might have a URI for identifying "the current
version" which is separate from the URI identifying each particular version" which is separate from the URI identifying each particular
version. In this case, a PUT request on a general URI might result version. In this case, a PUT request on a general URI might result
in several other URIs being defined by the origin server. in several other URIs being defined by the origin server.
HTTP/1.1 does not define how a PUT method affects the state of an HTTP/1.1 does not define how a PUT method affects the state of an
origin server. origin server.
Unless otherwise specified for a particular entity-header, the Header fields in a PUT request that are recognized as representation
entity-headers in the PUT request SHOULD be applied to the resource metadata SHOULD be applied to the resource created or modified by the
created or modified by the PUT. PUT. Unrecognized header fields SHOULD be ignored.
7.7. DELETE 7.7. DELETE
The DELETE method requests that the origin server delete the resource The DELETE method requests that the origin server delete the target
identified by the Effective Request URI. This method MAY be resource. This method MAY be overridden by human intervention (or
overridden by human intervention (or other means) on the origin other means) on the origin server. The client cannot be guaranteed
server. The client cannot be guaranteed that the operation has been that the operation has been carried out, even if the status code
carried out, even if the status code returned from the origin server returned from the origin server indicates that the action has been
indicates that the action has been completed successfully. However, completed successfully. However, the server SHOULD NOT indicate
the server SHOULD NOT indicate success unless, at the time the success unless, at the time the response is given, it intends to
response is given, it intends to delete the resource or move it to an delete the resource or move it to an inaccessible location.
inaccessible location.
A successful response SHOULD be 200 (OK) if the response includes an A successful response SHOULD be 200 (OK) if the response includes an
entity describing the status, 202 (Accepted) if the action has not representation describing the status, 202 (Accepted) if the action
yet been enacted, or 204 (No Content) if the action has been enacted has not yet been enacted, or 204 (No Content) if the action has been
but the response does not include an entity. enacted but the response does not include a representation.
If the request passes through a cache and the Effective Request URI If the request passes through a cache and the effective request URI
identifies one or more currently cached entities, those entries identifies one or more currently cached representations, those
SHOULD be treated as stale. Responses to this method are not entries SHOULD be treated as stale. Responses to the DELETE method
cacheable. are not cacheable.
7.8. TRACE 7.8. TRACE
The TRACE method is used to invoke a remote, application-layer loop- The TRACE method is used to invoke a remote, application-layer loop-
back of the request message. The final recipient of the request back of the request message. The final recipient of the request
SHOULD reflect the message received back to the client as the entity- SHOULD reflect the message received back to the client as the
body of a 200 (OK) response. The final recipient is either the message-body of a 200 (OK) response. The final recipient is either
origin server or the first proxy or gateway to receive a Max-Forwards the origin server or the first proxy or gateway to receive a Max-
value of zero (0) in the request (see Section 9.5). A TRACE request Forwards value of zero (0) in the request (see Section 9.5). A TRACE
MUST NOT include an entity. request MUST NOT include a message-body.
TRACE allows the client to see what is being received at the other TRACE allows the client to see what is being received at the other
end of the request chain and use that data for testing or diagnostic end of the request chain and use that data for testing or diagnostic
information. The value of the Via header field (Section 9.9 of information. The value of the Via header field (Section 9.9 of
[Part1]) is of particular interest, since it acts as a trace of the [Part1]) is of particular interest, since it acts as a trace of the
request chain. Use of the Max-Forwards header field allows the request chain. Use of the Max-Forwards header field allows the
client to limit the length of the request chain, which is useful for client to limit the length of the request chain, which is useful for
testing a chain of proxies forwarding messages in an infinite loop. testing a chain of proxies forwarding messages in an infinite loop.
If the request is valid, the response SHOULD contain the entire If the request is valid, the response SHOULD have a Content-Type of
request message in the entity-body, with a Content-Type of "message/ "message/http" (see Section 10.3.1 of [Part1]) and contain a message-
http" (see Section 10.3.1 of [Part1]). Responses to this method MUST body that encloses a copy of the entire request message. Responses
NOT be cached. to the TRACE method are not cacheable.
7.9. CONNECT 7.9. CONNECT
This specification reserves the method name CONNECT for use with a This specification reserves the method name CONNECT for use with a
proxy that can dynamically switch to being a tunnel (e.g., SSL proxy that can dynamically switch to being a tunnel (e.g., SSL
tunneling [RFC2817]). tunneling [RFC2817]).
8. Status Code Definitions 8. Status Code Definitions
Each Status-Code is described below, including any metainformation Each Status-Code is described below, including any metadata required
required in the response. in the response.
8.1. Informational 1xx 8.1. Informational 1xx
This class of status code indicates a provisional response, This class of status code indicates a provisional response,
consisting only of the Status-Line and optional headers, and is consisting only of the Status-Line and optional headers, and is
terminated by an empty line. There are no required headers for this terminated by an empty line. There are no required headers for this
class of status code. Since HTTP/1.0 did not define any 1xx status class of status code. Since HTTP/1.0 did not define any 1xx status
codes, servers MUST NOT send a 1xx response to an HTTP/1.0 client codes, servers MUST NOT send a 1xx response to an HTTP/1.0 client
except under experimental conditions. except under experimental conditions.
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synchronous protocol might be advantageous when delivering resources synchronous protocol might be advantageous when delivering resources
that use such features. that use such features.
8.2. Successful 2xx 8.2. Successful 2xx
This class of status code indicates that the client's request was This class of status code indicates that the client's request was
successfully received, understood, and accepted. successfully received, understood, and accepted.
8.2.1. 200 OK 8.2.1. 200 OK
The request has succeeded. The information returned with the The request has succeeded. The payload returned with the response is
response is dependent on the method used in the request, for example: dependent on the method used in the request, for example:
GET an entity corresponding to the requested resource is sent in the GET a representation of the target resource is sent in the response;
response;
HEAD the entity-header fields corresponding to the requested HEAD the same representation as GET, except without the message-
resource are sent in the response without any message-body; body;
POST an entity describing or containing the result of the action; POST a representation describing or containing the result of the
action;
TRACE an entity containing the request message as received by the TRACE a representation containing the request message as received by
end server. the end server.
Caches MAY use a heuristic (see Section 2.3.1.1 of [Part6]) to
determine freshness for 200 responses.
8.2.2. 201 Created 8.2.2. 201 Created
The request has been fulfilled and has resulted in a new resource The request has been fulfilled and has resulted in a new resource
being created. The newly created resource can be referenced by the being created. The newly created resource can be referenced by the
URI(s) returned in the entity of the response, with the most specific URI(s) returned in the payload of the response, with the most
URI for the resource given by a Location header field. The response specific URI for the resource given by a Location header field. The
SHOULD include an entity containing a list of resource response SHOULD include a payload containing a list of resource
characteristics and location(s) from which the user or user agent can characteristics and location(s) from which the user or user agent can
choose the one most appropriate. The entity format is specified by choose the one most appropriate. The payload format is specified by
the media type given in the Content-Type header field. The origin the media type given in the Content-Type header field. The origin
server MUST create the resource before returning the 201 status code. server MUST create the resource before returning the 201 status code.
If the action cannot be carried out immediately, the server SHOULD If the action cannot be carried out immediately, the server SHOULD
respond with 202 (Accepted) response instead. respond with 202 (Accepted) response instead.
A 201 response MAY contain an ETag response header field indicating A 201 response MAY contain an ETag response header field indicating
the current value of the entity tag for the requested variant just the current value of the entity-tag for the representation of the
created, see Section 6.1 of [Part4]. resource just created (see Section 6.1 of [Part4]).
8.2.3. 202 Accepted 8.2.3. 202 Accepted
The request has been accepted for processing, but the processing has The request has been accepted for processing, but the processing has
not been completed. The request might or might not eventually be not been completed. The request might or might not eventually be
acted upon, as it might be disallowed when processing actually takes acted upon, as it might be disallowed when processing actually takes
place. There is no facility for re-sending a status code from an place. There is no facility for re-sending a status code from an
asynchronous operation such as this. asynchronous operation such as this.
The 202 response is intentionally non-committal. Its purpose is to The 202 response is intentionally non-committal. Its purpose is to
allow a server to accept a request for some other process (perhaps a allow a server to accept a request for some other process (perhaps a
batch-oriented process that is only run once per day) without batch-oriented process that is only run once per day) without
requiring that the user agent's connection to the server persist requiring that the user agent's connection to the server persist
until the process is completed. The entity returned with this until the process is completed. The representation returned with
response SHOULD include an indication of the request's current status this response SHOULD include an indication of the request's current
and either a pointer to a status monitor or some estimate of when the status and either a pointer to a status monitor or some estimate of
user can expect the request to be fulfilled. when the user can expect the request to be fulfilled.
8.2.4. 203 Non-Authoritative Information 8.2.4. 203 Non-Authoritative Information
The returned metainformation in the entity-header is not the The returned metadata in the header fields is not the definitive set
definitive set as available from the origin server, but is gathered as available from the origin server, but is gathered from a local or
from a local or a third-party copy. The set presented MAY be a a third-party copy. The set presented MAY be a subset or superset of
subset or superset of the original version. For example, including the original version. For example, including local annotation
local annotation information about the resource might result in a information about the resource might result in a superset of the
superset of the metainformation known by the origin server. Use of metadata known by the origin server. Use of this response code is
this response code is not required and is only appropriate when the not required and is only appropriate when the response would
response would otherwise be 200 (OK). otherwise be 200 (OK).
Caches MAY use a heuristic (see Section 2.3.1.1 of [Part6]) to
determine freshness for 203 responses.
8.2.5. 204 No Content 8.2.5. 204 No Content
The server has fulfilled the request but does not need to return an The server has successfully fulfilled the request, but there is no
entity-body, and might want to return updated metainformation. The additional content to return in the response payload body. The
response MAY include new or updated metainformation in the form of resource metadata and representation metadata in the response
entity-headers, which if present SHOULD be associated with the message's header fields refer to the target resource and its current
requested variant. representation, respectively, after the requested action. For
example, if a 204 status code is received in response to a PUT and
the response contains an ETag header field, then the value of that
field is the current entity-tag for the representation that was
successfully PUT.
If the client is a user agent, it SHOULD NOT change its document view If the client is a user agent, it SHOULD NOT change its document view
from that which caused the request to be sent. This response is from that which caused the request to be sent. This response is
primarily intended to allow input for actions to take place without primarily intended to allow input for actions to take place without
causing a change to the user agent's active document view, although causing a change to the user agent's active document view, although
any new or updated metainformation SHOULD be applied to the document any new or updated metadata SHOULD be applied to the document
currently in the user agent's active view. currently in the user agent's active view.
The 204 response MUST NOT include a message-body, and thus is always The 204 response MUST NOT include a message-body, and thus is always
terminated by the first empty line after the header fields. terminated by the first empty line after the header fields.
8.2.6. 205 Reset Content 8.2.6. 205 Reset Content
The server has fulfilled the request and the user agent SHOULD reset The server has fulfilled the request and the user agent SHOULD reset
the document view which caused the request to be sent. This response the document view which caused the request to be sent. This response
is primarily intended to allow input for actions to take place via is primarily intended to allow input for actions to take place via
user input, followed by a clearing of the form in which the input is user input, followed by a clearing of the form in which the input is
given so that the user can easily initiate another input action. The given so that the user can easily initiate another input action. The
response MUST NOT include an entity. response MUST NOT include a message-body.
8.2.7. 206 Partial Content 8.2.7. 206 Partial Content
The server has fulfilled the partial GET request for the resource and The server has fulfilled the partial GET request for the resource and
the enclosed entity is a partial representation as defined in Section the enclosed payload is a partial representation as defined in
3.1 of [Part5]. Section 3.1 of [Part5].
Caches MAY use a heuristic (see Section 2.3.1.1 of [Part6]) to
determine freshness for 206 responses.
8.3. Redirection 3xx 8.3. Redirection 3xx
This class of status code indicates that further action needs to be This class of status code indicates that further action needs to be
taken by the user agent in order to fulfill the request. The action taken by the user agent in order to fulfill the request. The action
required MAY be carried out by the user agent without interaction required MAY be carried out by the user agent without interaction
with the user if and only if the method used in the second request is with the user if and only if the method used in the second request is
known to be "safe", as defined in Section 7.1.1. A client SHOULD known to be "safe", as defined in Section 7.1.1. A client SHOULD
detect infinite redirection loops, since such loops generate network detect infinite redirection loops, since such loops generate network
traffic for each redirection. traffic for each redirection.
Note: An earlier version of this specification recommended a Note: An earlier version of this specification recommended a
maximum of five redirections ([RFC2068], Section 10.3). Content maximum of five redirections ([RFC2068], Section 10.3). Content
developers should be aware that there might be clients that developers need to be aware that some clients might implement such
implement such a fixed limitation. a fixed limitation.
8.3.1. 300 Multiple Choices 8.3.1. 300 Multiple Choices
The requested resource corresponds to any one of a set of The target resource more than one representation, each with its own
representations, each with its own specific location, and agent- specific location, and agent-driven negotiation information (Section
driven negotiation information (Section 4 of [Part3]) is being 5 of [Part3]) is being provided so that the user (or user agent) can
provided so that the user (or user agent) can select a preferred select a preferred representation by redirecting its request to that
representation and redirect its request to that location. location.
Unless it was a HEAD request, the response SHOULD include an entity Unless it was a HEAD request, the response SHOULD include a
containing a list of resource characteristics and location(s) from representation containing a list of representation metadata and
which the user or user agent can choose the one most appropriate. location(s) from which the user or user agent can choose the one most
The entity format is specified by the media type given in the appropriate. The data format is specified by the media type given in
Content-Type header field. Depending upon the format and the the Content-Type header field. Depending upon the format and the
capabilities of the user agent, selection of the most appropriate capabilities of the user agent, selection of the most appropriate
choice MAY be performed automatically. However, this specification choice MAY be performed automatically. However, this specification
does not define any standard for such automatic selection. does not define any standard for such automatic selection.
If the server has a preferred choice of representation, it SHOULD If the server has a preferred choice of representation, it SHOULD
include the specific URI for that representation in the Location include the specific URI for that representation in the Location
field; user agents MAY use the Location field value for automatic field; user agents MAY use the Location field value for automatic
redirection. This response is cacheable unless indicated otherwise. redirection.
Caches MAY use a heuristic (see Section 2.3.1.1 of [Part6]) to
determine freshness for 300 responses.
8.3.2. 301 Moved Permanently 8.3.2. 301 Moved Permanently
The requested resource has been assigned a new permanent URI and any The target resource has been assigned a new permanent URI and any
future references to this resource SHOULD use one of the returned future references to this resource SHOULD use one of the returned
URIs. Clients with link editing capabilities ought to automatically URIs. Clients with link editing capabilities ought to automatically
re-link references to the Effective Request URI to one or more of the re-link references to the effective request URI to one or more of the
new references returned by the server, where possible. This response new references returned by the server, where possible.
is cacheable unless indicated otherwise.
Caches MAY use a heuristic (see Section 2.3.1.1 of [Part6]) to
determine freshness for 301 responses.
The new permanent URI SHOULD be given by the Location field in the The new permanent URI SHOULD be given by the Location field in the
response. Unless the request method was HEAD, the entity of the response. Unless the request method was HEAD, the representation of
response SHOULD contain a short hypertext note with a hyperlink to the response SHOULD contain a short hypertext note with a hyperlink
the new URI(s). to the new URI(s).
If the 301 status code is received in response to a request method If the 301 status code is received in response to a request method
that is known to be "safe", as defined in Section 7.1.1, then the that is known to be "safe", as defined in Section 7.1.1, then the
request MAY be automatically redirected by the user agent without request MAY be automatically redirected by the user agent without
confirmation. Otherwise, the user agent MUST NOT automatically confirmation. Otherwise, the user agent MUST NOT automatically
redirect the request unless it can be confirmed by the user, since redirect the request unless it can be confirmed by the user, since
this might change the conditions under which the request was issued. this might change the conditions under which the request was issued.
Note: When automatically redirecting a POST request after Note: When automatically redirecting a POST request after
receiving a 301 status code, some existing HTTP/1.0 user agents receiving a 301 status code, some existing HTTP/1.0 user agents
will erroneously change it into a GET request. will erroneously change it into a GET request.
8.3.3. 302 Found 8.3.3. 302 Found
The requested resource resides temporarily under a different URI. The target resource resides temporarily under a different URI. Since
Since the redirection might be altered on occasion, the client SHOULD the redirection might be altered on occasion, the client SHOULD
continue to use the Effectice Request URI for future requests. This continue to use the effective request URI for future requests.
response is only cacheable if indicated by a Cache-Control or Expires
header field.
The temporary URI SHOULD be given by the Location field in the The temporary URI SHOULD be given by the Location field in the
response. Unless the request method was HEAD, the entity of the response. Unless the request method was HEAD, the representation of
response SHOULD contain a short hypertext note with a hyperlink to the response SHOULD contain a short hypertext note with a hyperlink
the new URI(s). to the new URI(s).
If the 302 status code is received in response to a request method If the 302 status code is received in response to a request method
that is known to be "safe", as defined in Section 7.1.1, then the that is known to be "safe", as defined in Section 7.1.1, then the
request MAY be automatically redirected by the user agent without request MAY be automatically redirected by the user agent without
confirmation. Otherwise, the user agent MUST NOT automatically confirmation. Otherwise, the user agent MUST NOT automatically
redirect the request unless it can be confirmed by the user, since redirect the request unless it can be confirmed by the user, since
this might change the conditions under which the request was issued. this might change the conditions under which the request was issued.
Note: HTTP/1.0 ([RFC1945], Section 9.3) and the first version of Note: HTTP/1.0 ([RFC1945], Section 9.3) and the first version of
HTTP/1.1 ([RFC2068], Section 10.3.3) specify that the client is HTTP/1.1 ([RFC2068], Section 10.3.3) specify that the client is
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client. client.
8.3.4. 303 See Other 8.3.4. 303 See Other
The server directs the user agent to a different resource, indicated The server directs the user agent to a different resource, indicated
by a URI in the Location header field, that provides an indirect by a URI in the Location header field, that provides an indirect
response to the original request. The user agent MAY perform a GET response to the original request. The user agent MAY perform a GET
request on the URI in the Location field in order to obtain a request on the URI in the Location field in order to obtain a
representation corresponding to the response, be redirected again, or representation corresponding to the response, be redirected again, or
end with an error status. The Location URI is not a substitute end with an error status. The Location URI is not a substitute
reference for the originally requested resource. reference for the effective request URI.
The 303 status is generally applicable to any HTTP method. It is The 303 status code is generally applicable to any HTTP method. It
primarily used to allow the output of a POST action to redirect the is primarily used to allow the output of a POST action to redirect
user agent to a selected resource, since doing so provides the the user agent to a selected resource, since doing so provides the
information corresponding to the POST response in a form that can be information corresponding to the POST response in a form that can be
separately identified, bookmarked, and cached independent of the separately identified, bookmarked, and cached independent of the
original request. original request.
A 303 response to a GET request indicates that the requested resource A 303 response to a GET request indicates that the requested resource
does not have a representation of its own that can be transferred by does not have a representation of its own that can be transferred by
the server over HTTP. The Location URI indicates a resource that is the server over HTTP. The Location URI indicates a resource that is
descriptive of the requested resource such that the follow-on descriptive of the target resource, such that the follow-on
representation may be useful without implying that it adequately representation might be useful to recipients without implying that it
represents the previously requested resource. Note that answers to adequately represents the target resource. Note that answers to the
the questions of what can be represented, what representations are questions of what can be represented, what representations are
adequate, and what might be a useful description are outside the adequate, and what might be a useful description are outside the
scope of HTTP and thus entirely determined by the URI owner(s). scope of HTTP and thus entirely determined by the URI owner(s).
A 303 response SHOULD NOT be cached unless it is indicated as Except for responses to a HEAD request, the representation of a 303
cacheable by Cache-Control or Expires header fields. Except for response SHOULD contain a short hypertext note with a hyperlink to
responses to a HEAD request, the entity of a 303 response SHOULD the Location URI.
contain a short hypertext note with a hyperlink to the Location URI.
8.3.5. 304 Not Modified 8.3.5. 304 Not Modified
The response to the request has not been modified since the The response to the request has not been modified since the
conditions indicated by the client's conditional GET request, as conditions indicated by the client's conditional GET request, as
defined in Section 3.1 of [Part4]. defined in Section 3.1 of [Part4].
8.3.6. 305 Use Proxy 8.3.6. 305 Use Proxy
The 305 status was defined in a previous version of this The 305 status code was defined in a previous version of this
specification (see Appendix A.2), and is now deprecated. specification (see Appendix A), and is now deprecated.
8.3.7. 306 (Unused) 8.3.7. 306 (Unused)
The 306 status code was used in a previous version of the The 306 status code was used in a previous version of the
specification, is no longer used, and the code is reserved. specification, is no longer used, and the code is reserved.
8.3.8. 307 Temporary Redirect 8.3.8. 307 Temporary Redirect
The requested resource resides temporarily under a different URI. The target resource resides temporarily under a different URI. Since
Since the redirection MAY be altered on occasion, the client SHOULD the redirection can change over time, the client SHOULD continue to
continue to use the Effective Request URI for future requests. This use the effective request URI for future requests.
response is only cacheable if indicated by a Cache-Control or Expires
header field.
The temporary URI SHOULD be given by the Location field in the The temporary URI SHOULD be given by the Location field in the
response. Unless the request method was HEAD, the entity of the response. Unless the request method was HEAD, the representation of
response SHOULD contain a short hypertext note with a hyperlink to the response SHOULD contain a short hypertext note with a hyperlink
the new URI(s) , since many pre-HTTP/1.1 user agents do not to the new URI(s) , since many pre-HTTP/1.1 user agents do not
understand the 307 status. Therefore, the note SHOULD contain the understand the 307 status code. Therefore, the note SHOULD contain
information necessary for a user to repeat the original request on the information necessary for a user to repeat the original request
the new URI. on the new URI.
If the 307 status code is received in response to a request method If the 307 status code is received in response to a request method
that is known to be "safe", as defined in Section 7.1.1, then the that is known to be "safe", as defined in Section 7.1.1, then the
request MAY be automatically redirected by the user agent without request MAY be automatically redirected by the user agent without
confirmation. Otherwise, the user agent MUST NOT automatically confirmation. Otherwise, the user agent MUST NOT automatically
redirect the request unless it can be confirmed by the user, since redirect the request unless it can be confirmed by the user, since
this might change the conditions under which the request was issued. this might change the conditions under which the request was issued.
8.4. Client Error 4xx 8.4. Client Error 4xx
The 4xx class of status code is intended for cases in which the The 4xx class of status code is intended for cases in which the
client seems to have erred. Except when responding to a HEAD client seems to have erred. Except when responding to a HEAD
request, the server SHOULD include an entity containing an request, the server SHOULD include a representation containing an
explanation of the error situation, and whether it is a temporary or explanation of the error situation, and whether it is a temporary or
permanent condition. These status codes are applicable to any permanent condition. These status codes are applicable to any
request method. User agents SHOULD display any included entity to request method. User agents SHOULD display any included
the user. representation to the user.
If the client is sending data, a server implementation using TCP If the client is sending data, a server implementation using TCP
SHOULD be careful to ensure that the client acknowledges receipt of SHOULD be careful to ensure that the client acknowledges receipt of
the packet(s) containing the response, before the server closes the the packet(s) containing the response, before the server closes the
input connection. If the client continues sending data to the server input connection. If the client continues sending data to the server
after the close, the server's TCP stack will send a reset packet to after the close, the server's TCP stack will send a reset packet to
the client, which may erase the client's unacknowledged input buffers the client, which might erase the client's unacknowledged input
before they can be read and interpreted by the HTTP application. buffers before they can be read and interpreted by the HTTP
application.
8.4.1. 400 Bad Request 8.4.1. 400 Bad Request
The request could not be understood by the server due to malformed The request could not be understood by the server due to malformed
syntax. The client SHOULD NOT repeat the request without syntax. The client SHOULD NOT repeat the request without
modifications. modifications.
8.4.2. 401 Unauthorized 8.4.2. 401 Unauthorized
The request requires user authentication (see Section 2.1 of The request requires user authentication (see Section 2.1 of
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8.4.3. 402 Payment Required 8.4.3. 402 Payment Required
This code is reserved for future use. This code is reserved for future use.
8.4.4. 403 Forbidden 8.4.4. 403 Forbidden
The server understood the request, but is refusing to fulfill it. The server understood the request, but is refusing to fulfill it.
Authorization will not help and the request SHOULD NOT be repeated. Authorization will not help and the request SHOULD NOT be repeated.
If the request method was not HEAD and the server wishes to make If the request method was not HEAD and the server wishes to make
public why the request has not been fulfilled, it SHOULD describe the public why the request has not been fulfilled, it SHOULD describe the
reason for the refusal in the entity. If the server does not wish to reason for the refusal in the representation. If the server does not
make this information available to the client, the status code 404 wish to make this information available to the client, the status
(Not Found) can be used instead. code 404 (Not Found) can be used instead.
8.4.5. 404 Not Found 8.4.5. 404 Not Found
The server has not found anything matching the Effective Request URI. The server has not found anything matching the effective request URI.
No indication is given of whether the condition is temporary or No indication is given of whether the condition is temporary or
permanent. The 410 (Gone) status code SHOULD be used if the server permanent. The 410 (Gone) status code SHOULD be used if the server
knows, through some internally configurable mechanism, that an old knows, through some internally configurable mechanism, that an old
resource is permanently unavailable and has no forwarding address. resource is permanently unavailable and has no forwarding address.
This status code is commonly used when the server does not wish to This status code is commonly used when the server does not wish to
reveal exactly why the request has been refused, or when no other reveal exactly why the request has been refused, or when no other
response is applicable. response is applicable.
8.4.6. 405 Method Not Allowed 8.4.6. 405 Method Not Allowed
The method specified in the Request-Line is not allowed for the The method specified in the Request-Line is not allowed for the
resource identified by the Effective Request URI. The response MUST target resource. The response MUST include an Allow header
include an Allow header containing a list of valid methods for the containing a list of valid methods for the requested resource.
requested resource.
8.4.7. 406 Not Acceptable 8.4.7. 406 Not Acceptable
The resource identified by the request is only capable of generating The resource identified by the request is only capable of generating
response entities which have content characteristics not acceptable response representations which have content characteristics not
according to the accept headers sent in the request. acceptable according to the accept headers sent in the request.
Unless it was a HEAD request, the response SHOULD include an entity Unless it was a HEAD request, the response SHOULD include a
containing a list of available entity characteristics and location(s) representation containing a list of available representation
from which the user or user agent can choose the one most characteristics and location(s) from which the user or user agent can
appropriate. The entity format is specified by the media type given choose the one most appropriate. The data format is specified by the
in the Content-Type header field. Depending upon the format and the media type given in the Content-Type header field. Depending upon
capabilities of the user agent, selection of the most appropriate the format and the capabilities of the user agent, selection of the
choice MAY be performed automatically. However, this specification most appropriate choice MAY be performed automatically. However,
does not define any standard for such automatic selection. this specification does not define any standard for such automatic
selection.
Note: HTTP/1.1 servers are allowed to return responses which are Note: HTTP/1.1 servers are allowed to return responses which are
not acceptable according to the accept headers sent in the not acceptable according to the accept headers sent in the
request. In some cases, this may even be preferable to sending a request. In some cases, this might even be preferable to sending
406 response. User agents are encouraged to inspect the headers a 406 response. User agents are encouraged to inspect the headers
of an incoming response to determine if it is acceptable. of an incoming response to determine if it is acceptable.
If the response could be unacceptable, a user agent SHOULD If the response could be unacceptable, a user agent SHOULD
temporarily stop receipt of more data and query the user for a temporarily stop receipt of more data and query the user for a
decision on further actions. decision on further actions.
8.4.8. 407 Proxy Authentication Required 8.4.8. 407 Proxy Authentication Required
This code is similar to 401 (Unauthorized), but indicates that the This code is similar to 401 (Unauthorized), but indicates that the
client must first authenticate itself with the proxy (see Section 2.2 client must first authenticate itself with the proxy (see Section 2.2
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was prepared to wait. The client MAY repeat the request without was prepared to wait. The client MAY repeat the request without
modifications at any later time. modifications at any later time.
8.4.10. 409 Conflict 8.4.10. 409 Conflict
The request could not be completed due to a conflict with the current The request could not be completed due to a conflict with the current
state of the resource. This code is only allowed in situations where state of the resource. This code is only allowed in situations where
it is expected that the user might be able to resolve the conflict it is expected that the user might be able to resolve the conflict
and resubmit the request. The response body SHOULD include enough and resubmit the request. The response body SHOULD include enough
information for the user to recognize the source of the conflict. information for the user to recognize the source of the conflict.
Ideally, the response entity would include enough information for the Ideally, the response representation would include enough information
user or user agent to fix the problem; however, that might not be for the user or user agent to fix the problem; however, that might
possible and is not required. not be possible and is not required.
Conflicts are most likely to occur in response to a PUT request. For Conflicts are most likely to occur in response to a PUT request. For
example, if versioning were being used and the entity being PUT example, if versioning were being used and the representation being
included changes to a resource which conflict with those made by an PUT included changes to a resource which conflict with those made by
earlier (third-party) request, the server might use the 409 response an earlier (third-party) request, the server might use the 409
to indicate that it can't complete the request. In this case, the response to indicate that it can't complete the request. In this
response entity would likely contain a list of the differences case, the response representation would likely contain a list of the
between the two versions in a format defined by the response Content- differences between the two versions in a format defined by the
Type. response Content-Type.
8.4.11. 410 Gone 8.4.11. 410 Gone
The requested resource is no longer available at the server and no The target resource is no longer available at the server and no
forwarding address is known. This condition is expected to be forwarding address is known. This condition is expected to be
considered permanent. Clients with link editing capabilities SHOULD considered permanent. Clients with link editing capabilities SHOULD
delete references to the Effective Request URI after user approval. delete references to the effective request URI after user approval.
If the server does not know, or has no facility to determine, whether If the server does not know, or has no facility to determine, whether
or not the condition is permanent, the status code 404 (Not Found) or not the condition is permanent, the status code 404 (Not Found)
SHOULD be used instead. This response is cacheable unless indicated SHOULD be used instead.
otherwise.
The 410 response is primarily intended to assist the task of web The 410 response is primarily intended to assist the task of web
maintenance by notifying the recipient that the resource is maintenance by notifying the recipient that the resource is
intentionally unavailable and that the server owners desire that intentionally unavailable and that the server owners desire that
remote links to that resource be removed. Such an event is common remote links to that resource be removed. Such an event is common
for limited-time, promotional services and for resources belonging to for limited-time, promotional services and for resources belonging to
individuals no longer working at the server's site. It is not individuals no longer working at the server's site. It is not
necessary to mark all permanently unavailable resources as "gone" or necessary to mark all permanently unavailable resources as "gone" or
to keep the mark for any length of time -- that is left to the to keep the mark for any length of time -- that is left to the
discretion of the server owner. discretion of the server owner.
Caches MAY use a heuristic (see Section 2.3.1.1 of [Part6]) to
determine freshness for 410 responses.
8.4.12. 411 Length Required 8.4.12. 411 Length Required
The server refuses to accept the request without a defined Content- The server refuses to accept the request without a defined Content-
Length. The client MAY repeat the request if it adds a valid Length. The client MAY repeat the request if it adds a valid
Content-Length header field containing the length of the message-body Content-Length header field containing the length of the message-body
in the request message. in the request message.
8.4.13. 412 Precondition Failed 8.4.13. 412 Precondition Failed
The precondition given in one or more of the request-header fields The precondition given in one or more of the request-header fields
evaluated to false when it was tested on the server, as defined in evaluated to false when it was tested on the server, as defined in
Section 3.2 of [Part4]. Section 3.2 of [Part4].
8.4.14. 413 Request Entity Too Large 8.4.14. 413 Request Entity Too Large
The server is refusing to process a request because the request The server is refusing to process a request because the request
entity is larger than the server is willing or able to process. The representation is larger than the server is willing or able to
server MAY close the connection to prevent the client from continuing process. The server MAY close the connection to prevent the client
the request. from continuing the request.
If the condition is temporary, the server SHOULD include a Retry- If the condition is temporary, the server SHOULD include a Retry-
After header field to indicate that it is temporary and after what After header field to indicate that it is temporary and after what
time the client MAY try again. time the client MAY try again.
8.4.15. 414 URI Too Long 8.4.15. 414 URI Too Long
The server is refusing to service the request because the Effective The server is refusing to service the request because the effective
Request URI is longer than the server is willing to interpret. This request URI is longer than the server is willing to interpret. This
rare condition is only likely to occur when a client has improperly rare condition is only likely to occur when a client has improperly
converted a POST request to a GET request with long query converted a POST request to a GET request with long query
information, when the client has descended into a URI "black hole" of information, when the client has descended into a URI "black hole" of
redirection (e.g., a redirected URI prefix that points to a suffix of redirection (e.g., a redirected URI prefix that points to a suffix of
itself), or when the server is under attack by a client attempting to itself), or when the server is under attack by a client attempting to
exploit security holes present in some servers using fixed-length exploit security holes present in some servers using fixed-length
buffers for reading or manipulating the Effective Request URI. buffers for reading or manipulating the effective request URI.
8.4.16. 415 Unsupported Media Type 8.4.16. 415 Unsupported Media Type
The server is refusing to service the request because the entity of The server is refusing to service the request because the
the request is in a format not supported by the requested resource representation of the request is in a format not supported by the
for the requested method. target resource for the requested method.
8.4.17. 416 Requested Range Not Satisfiable 8.4.17. 416 Requested Range Not Satisfiable
The request included a Range request-header field (Section 5.4 of The request included a Range request-header field (Section 5.4 of
[Part5]) and none of the range-specifier values in this field overlap [Part5]) and none of the range-specifier values in this field overlap
the current extent of the selected resource. See Section 3.2 of the current extent of the selected resource. See Section 3.2 of
[Part5] [Part5].
8.4.18. 417 Expectation Failed 8.4.18. 417 Expectation Failed
The expectation given in an Expect request-header field (see The expectation given in an Expect request-header field (see
Section 9.2) could not be met by this server, or, if the server is a Section 9.2) could not be met by this server, or, if the server is a
proxy, the server has unambiguous evidence that the request could not proxy, the server has unambiguous evidence that the request could not
be met by the next-hop server. be met by the next-hop server.
8.5. Server Error 5xx 8.5. Server Error 5xx
Response status codes beginning with the digit "5" indicate cases in Response status codes beginning with the digit "5" indicate cases in
which the server is aware that it has erred or is incapable of which the server is aware that it has erred or is incapable of
performing the request. Except when responding to a HEAD request, performing the request. Except when responding to a HEAD request,
the server SHOULD include an entity containing an explanation of the the server SHOULD include a representation containing an explanation
error situation, and whether it is a temporary or permanent of the error situation, and whether it is a temporary or permanent
condition. User agents SHOULD display any included entity to the condition. User agents SHOULD display any included representation to
user. These response codes are applicable to any request method. the user. These response codes are applicable to any request method.
8.5.1. 500 Internal Server Error 8.5.1. 500 Internal Server Error
The server encountered an unexpected condition which prevented it The server encountered an unexpected condition which prevented it
from fulfilling the request. from fulfilling the request.
8.5.2. 501 Not Implemented 8.5.2. 501 Not Implemented
The server does not support the functionality required to fulfill the The server does not support the functionality required to fulfill the
request. This is the appropriate response when the server does not request. This is the appropriate response when the server does not
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8.5.4. 503 Service Unavailable 8.5.4. 503 Service Unavailable
The server is currently unable to handle the request due to a The server is currently unable to handle the request due to a
temporary overloading or maintenance of the server. The implication temporary overloading or maintenance of the server. The implication
is that this is a temporary condition which will be alleviated after is that this is a temporary condition which will be alleviated after
some delay. If known, the length of the delay MAY be indicated in a some delay. If known, the length of the delay MAY be indicated in a
Retry-After header. If no Retry-After is given, the client SHOULD Retry-After header. If no Retry-After is given, the client SHOULD
handle the response as it would for a 500 response. handle the response as it would for a 500 response.
Note: The existence of the 503 status code does not imply that a Note: The existence of the 503 status code does not imply that a
server must use it when becoming overloaded. Some servers may server must use it when becoming overloaded. Some servers might
wish to simply refuse the connection. wish to simply refuse the connection.
8.5.5. 504 Gateway Timeout 8.5.5. 504 Gateway Timeout
The server, while acting as a gateway or proxy, did not receive a The server, while acting as a gateway or proxy, did not receive a
timely response from the upstream server specified by the URI (e.g., timely response from the upstream server specified by the URI (e.g.,
HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed
to access in attempting to complete the request. to access in attempting to complete the request.
Note to implementors: some deployed proxies are known to return Note to implementors: some deployed proxies are known to return
400 or 500 when DNS lookups time out. 400 or 500 when DNS lookups time out.
8.5.6. 505 HTTP Version Not Supported 8.5.6. 505 HTTP Version Not Supported
The server does not support, or refuses to support, the protocol The server does not support, or refuses to support, the protocol
version that was used in the request message. The server is version that was used in the request message. The server is
indicating that it is unable or unwilling to complete the request indicating that it is unable or unwilling to complete the request
using the same major version as the client, as described in Section using the same major version as the client, as described in Section
2.5 of [Part1], other than with this error message. The response 2.5 of [Part1], other than with this error message. The response
SHOULD contain an entity describing why that version is not supported SHOULD contain a representation describing why that version is not
and what other protocols are supported by that server. supported and what other protocols are supported by that server.
9. Header Field Definitions 9. 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 request and response semantics. fields related to request and response semantics.
For entity-header fields, both sender and recipient refer to either
the client or the server, depending on who sends and who receives the
entity.
9.1. Allow 9.1. Allow
The "Allow" response-header field lists the set of methods advertised The "Allow" response-header field lists the set of methods advertised
as supported by the resource identified by the Effective Request URI. as supported by the target resource. The purpose of this field is
The purpose of this field is strictly to inform the recipient of strictly to inform the recipient of valid methods associated with the
valid methods associated with the resource. resource.
Allow = "Allow" ":" OWS Allow-v Allow = "Allow" ":" OWS Allow-v
Allow-v = #Method Allow-v = #Method
Example of use: Example of use:
Allow: GET, HEAD, PUT Allow: GET, HEAD, PUT
The actual set of allowed methods is defined by the origin server at The actual set of allowed methods is defined by the origin server at
the time of each request. the time of each request.
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Expect = "Expect" ":" OWS Expect-v Expect = "Expect" ":" OWS Expect-v
Expect-v = 1#expectation Expect-v = 1#expectation
expectation = "100-continue" / expectation-extension expectation = "100-continue" / expectation-extension
expectation-extension = token [ "=" ( token / quoted-string ) expectation-extension = token [ "=" ( token / quoted-string )
*expect-params ] *expect-params ]
expect-params = ";" token [ "=" ( token / quoted-string ) ] expect-params = ";" token [ "=" ( token / quoted-string ) ]
A server that does not understand or is unable to comply with any of A server that does not understand or is unable to comply with any of
the expectation values in the Expect field of a request MUST respond the expectation values in the Expect field of a request MUST respond
with appropriate error status. The server MUST respond with a 417 with appropriate error status code. The server MUST respond with a
(Expectation Failed) status if any of the expectations cannot be met 417 (Expectation Failed) status code if any of the expectations
or, if there are other problems with the request, some other 4xx cannot be met or, if there are other problems with the request, some
status. other 4xx status code.
This header field is defined with extensible syntax to allow for This header field is defined with extensible syntax to allow for
future extensions. If a server receives a request containing an future extensions. If a server receives a request containing an
Expect field that includes an expectation-extension that it does not Expect field that includes an expectation-extension that it does not
support, it MUST respond with a 417 (Expectation Failed) status. support, it MUST respond with a 417 (Expectation Failed) status code.
Comparison of expectation values is case-insensitive for unquoted Comparison of expectation values is case-insensitive for unquoted
tokens (including the 100-continue token), and is case-sensitive for tokens (including the 100-continue token), and is case-sensitive for
quoted-string expectation-extensions. quoted-string expectation-extensions.
The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy MUST The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy MUST
return a 417 (Expectation Failed) status if it receives a request return a 417 (Expectation Failed) status code if it receives a
with an expectation that it cannot meet. However, the Expect request with an expectation that it cannot meet. However, the Expect
request-header itself is end-to-end; it MUST be forwarded if the request-header itself is end-to-end; it MUST be forwarded if the
request is forwarded. request is forwarded.
Many older HTTP/1.0 and HTTP/1.1 applications do not understand the Many older HTTP/1.0 and HTTP/1.1 applications do not understand the
Expect header. Expect header.
See Section 7.2.3 of [Part1] for the use of the 100 (Continue) See Section 7.2.3 of [Part1] for the use of the 100 (Continue) status
status. code.
9.3. From 9.3. From
The "From" request-header field, if given, SHOULD contain an Internet The "From" request-header field, if given, SHOULD contain an Internet
e-mail address for the human user who controls the requesting user e-mail address for the human user who controls the requesting user
agent. The address SHOULD be machine-usable, as defined by "mailbox" agent. The address SHOULD be machine-usable, as defined by "mailbox"
in Section 3.4 of [RFC5322]: in Section 3.4 of [RFC5322]:
From = "From" ":" OWS From-v From = "From" ":" OWS From-v
From-v = mailbox From-v = mailbox
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o With a 201 Created response, because in this usage the Location o With a 201 Created response, because in this usage the Location
header specifies the URI for the entire created resource. header specifies the URI for the entire created resource.
o With 305 Use Proxy. o With 305 Use Proxy.
Note: This specification does not define precedence rules for the Note: This specification does not define precedence rules for the
case where the original URI, as navigated to by the user agent, case where the original URI, as navigated to by the user agent,
and the Location header field value both contain fragment and the Location header field value both contain fragment
identifiers. identifiers.
Note: The Content-Location header field (Section 5.7 of [Part3]) Note: The Content-Location header field (Section 6.7 of [Part3])
differs from Location in that the Content-Location identifies the differs from Location in that the Content-Location identifies the
original location of the entity enclosed in the response. It is most specific resource corresponding to the enclosed
therefore possible for a response to contain header fields for representation. It is therefore possible for a response to
both Location and Content-Location. contain header fields for both Location and Content-Location.
9.5. Max-Forwards 9.5. Max-Forwards
The "Max-Forwards" request-header field provides a mechanism with the The "Max-Forwards" request-header field provides a mechanism with the
TRACE (Section 7.8) and OPTIONS (Section 7.2) methods to limit the TRACE (Section 7.8) and OPTIONS (Section 7.2) methods to limit the
number of times that the request is forwarded by proxies or gateways. number of times that the request is forwarded by proxies or gateways.
This can be useful when the client is attempting to trace a request This can be useful when the client is attempting to trace a request
which appears to be failing or looping in mid-chain. which appears to be failing or looping in mid-chain.
Max-Forwards = "Max-Forwards" ":" OWS Max-Forwards-v Max-Forwards = "Max-Forwards" ":" OWS Max-Forwards-v
Max-Forwards-v = 1*DIGIT Max-Forwards-v = 1*DIGIT
The Max-Forwards value is a decimal integer indicating the remaining The Max-Forwards value is a decimal integer indicating the remaining
number of times this request message may be forwarded. number of times this request message can be forwarded.
Each proxy or gateway recipient of a TRACE or OPTIONS request Each proxy or gateway recipient of a TRACE or OPTIONS request
containing a Max-Forwards header field MUST check and update its containing a Max-Forwards header field MUST check and update its
value prior to forwarding the request. If the received value is zero value prior to forwarding the request. If the received value is zero
(0), the recipient MUST NOT forward the request; instead, it MUST (0), the recipient MUST NOT forward the request; instead, it MUST
respond as the final recipient. If the received Max-Forwards value respond as the final recipient. If the received Max-Forwards value
is greater than zero, then the forwarded message MUST contain an is greater than zero, then the forwarded message MUST contain an
updated Max-Forwards field with a value decremented by one (1). updated Max-Forwards field with a value decremented by one (1).
The Max-Forwards header field MAY be ignored for all other methods The Max-Forwards header field MAY be ignored for all other methods
defined by this specification and for any extension methods for which defined by this specification and for any extension methods for which
it is not explicitly referred to as part of that method definition. it is not explicitly referred to as part of that method definition.
9.6. Referer 9.6. Referer
The "Referer" [sic] request-header field allows the client to specify The "Referer" [sic] request-header field allows the client to specify
the URI of the resource from which the Effective Request URI was the URI of the resource from which the effective request URI was
obtained (the "referrer", although the header field is misspelled.). obtained (the "referrer", although the header field is misspelled.).
The Referer header allows servers to generate lists of back-links to The Referer header allows servers to generate lists of back-links to
resources for interest, logging, optimized caching, etc. It also resources for interest, logging, optimized caching, etc. It also
allows obsolete or mistyped links to be traced for maintenance. Some allows obsolete or mistyped links to be traced for maintenance. Some
servers use Referer as a means of controlling where they allow links servers use Referer as a means of controlling where they allow links
from (so-called "deep linking"), but it should be noted that from (so-called "deep linking"), but legitimate requests do not
legitimate requests are not required to contain a Referer header always contain a Referer header field.
field.
If the Effective Request URI was obtained from a source that does not If the effective request URI was obtained from a source that does not
have its own URI (e.g., input from the user keyboard), the Referer have its own URI (e.g., input from the user keyboard), the Referer
field MUST either be sent with the value "about:blank", or not be field MUST either be sent with the value "about:blank", or not be
sent at all. Note that this requirement does not apply to sources sent at all. Note that this requirement does not apply to sources
with non-HTTP URIs (e.g., FTP). with non-HTTP URIs (e.g., FTP).
Referer = "Referer" ":" OWS Referer-v Referer = "Referer" ":" OWS Referer-v
Referer-v = absolute-URI / partial-URI Referer-v = absolute-URI / partial-URI
Example: Example:
Referer: http://www.example.org/hypertext/Overview.html Referer: http://www.example.org/hypertext/Overview.html
If the field value is a relative URI, it SHOULD be interpreted If the field value is a relative URI, it SHOULD be interpreted
relative to the Effective Request URI. The URI MUST NOT include a relative to the effective request URI. The URI MUST NOT include a
fragment. See Section 11.2 for security considerations. fragment. See Section 11.2 for security considerations.
9.7. Retry-After 9.7. Retry-After
The response-header "Retry-After" field can be used with a 503 The response-header "Retry-After" field can be used with a 503
(Service Unavailable) response to indicate how long the service is (Service Unavailable) response to indicate how long the service is
expected to be unavailable to the requesting client. This field MAY expected to be unavailable to the requesting client. This field MAY
also be used with any 3xx (Redirection) response to indicate the also be used with any 3xx (Redirection) response to indicate the
minimum time the user-agent is asked wait before issuing the minimum time the user-agent is asked wait before issuing the
redirected request. redirected request.
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User-Agent: CERN-LineMode/2.15 libwww/2.17b3 User-Agent: CERN-LineMode/2.15 libwww/2.17b3
10. IANA Considerations 10. IANA Considerations
10.1. Method Registry 10.1. Method Registry
The registration procedure for HTTP Methods is defined by Section 2.1 The registration procedure for HTTP Methods is defined by Section 2.1
of this document. of this document.
The HTTP Method Registry should be created at The HTTP Method Registry shall be created at
<http://www.iana.org/assignments/http-methods> and be populated with <http://www.iana.org/assignments/http-methods> and be populated with
the registrations below: the registrations below:
+---------+------+-------------+ +---------+------+-------------+
| Method | Safe | Reference | | Method | Safe | Reference |
+---------+------+-------------+ +---------+------+-------------+
| CONNECT | no | Section 7.9 | | CONNECT | no | Section 7.9 |
| DELETE | no | Section 7.7 | | DELETE | no | Section 7.7 |
| GET | yes | Section 7.3 | | GET | yes | Section 7.3 |
| HEAD | yes | Section 7.4 | | HEAD | yes | Section 7.4 |
skipping to change at page 38, line 38 skipping to change at page 38, line 51
| TRACE | yes | Section 7.8 | | TRACE | yes | Section 7.8 |
+---------+------+-------------+ +---------+------+-------------+
10.2. Status Code Registry 10.2. Status Code Registry
The registration procedure for HTTP Status Codes -- previously The registration procedure for HTTP Status Codes -- previously
defined in Section 7.1 of [RFC2817] -- is now defined by Section 4.1 defined in Section 7.1 of [RFC2817] -- is now defined by Section 4.1
of this document. of this document.
The HTTP Status Code Registry located at The HTTP Status Code Registry located at
<http://www.iana.org/assignments/http-status-codes> should be updated <http://www.iana.org/assignments/http-status-codes> shall be updated
with the registrations below: with the registrations below:
+-------+-------------------------------+----------------+ +-------+-------------------------------+----------------+
| Value | Description | Reference | | Value | Description | Reference |
+-------+-------------------------------+----------------+ +-------+-------------------------------+----------------+
| 100 | Continue | Section 8.1.1 | | 100 | Continue | Section 8.1.1 |
| 101 | Switching Protocols | Section 8.1.2 | | 101 | Switching Protocols | Section 8.1.2 |
| 200 | OK | Section 8.2.1 | | 200 | OK | Section 8.2.1 |
| 201 | Created | Section 8.2.2 | | 201 | Created | Section 8.2.2 |
| 202 | Accepted | Section 8.2.3 | | 202 | Accepted | Section 8.2.3 |
skipping to change at page 39, line 46 skipping to change at page 39, line 46
| 415 | Unsupported Media Type | Section 8.4.16 | | 415 | Unsupported Media Type | Section 8.4.16 |
| 417 | Expectation Failed | Section 8.4.18 | | 417 | Expectation Failed | Section 8.4.18 |
| 500 | Internal Server Error | Section 8.5.1 | | 500 | Internal Server Error | Section 8.5.1 |
| 501 | Not Implemented | Section 8.5.2 | | 501 | Not Implemented | Section 8.5.2 |
| 502 | Bad Gateway | Section 8.5.3 | | 502 | Bad Gateway | Section 8.5.3 |
| 503 | Service Unavailable | Section 8.5.4 | | 503 | Service Unavailable | Section 8.5.4 |
| 504 | Gateway Timeout | Section 8.5.5 | | 504 | Gateway Timeout | Section 8.5.5 |
| 505 | HTTP Version Not Supported | Section 8.5.6 | | 505 | HTTP Version Not Supported | Section 8.5.6 |
+-------+-------------------------------+----------------+ +-------+-------------------------------+----------------+
10.3. Message Header Registration 10.3. Header Field Registration
The Message Header 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> should 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 |
+-------------------+----------+----------+-------------+ +-------------------+----------+----------+-------------+
| Allow | http | standard | Section 9.1 | | Allow | http | standard | Section 9.1 |
| Expect | http | standard | Section 9.2 | | Expect | http | standard | Section 9.2 |
| From | http | standard | Section 9.3 | | From | http | standard | Section 9.3 |
| Location | http | standard | Section 9.4 | | Location | http | standard | Section 9.4 |
| Max-Forwards | http | standard | Section 9.5 | | Max-Forwards | http | standard | Section 9.5 |
skipping to change at page 41, line 26 skipping to change at page 41, line 26
We suggest, though do not require, that a convenient toggle interface We suggest, though do not require, that a convenient toggle interface
be provided for the user to enable or disable the sending of From and be provided for the user to enable or disable the sending of From and
Referer information. Referer information.
The User-Agent (Section 9.9) or Server (Section 9.8) header fields The User-Agent (Section 9.9) or Server (Section 9.8) header fields
can sometimes be used to determine that a specific client or server can sometimes be used to determine that a specific client or server
have a particular security hole which might be exploited. have a particular security hole which might be exploited.
Unfortunately, this same information is often used for other valuable Unfortunately, this same information is often used for other valuable
purposes for which HTTP currently has no better mechanism. purposes for which HTTP currently has no better mechanism.
Some methods, like TRACE (Section 7.8) may expose information sent in Some methods, like TRACE (Section 7.8), expose information that was
request headers in the response entity. Clients SHOULD be careful sent in request headers within the body of their response. Clients
with sensitive information, like Cookies, Authorization credentials SHOULD be careful with sensitive information, like Cookies,
and other headers that might be used to collect data from the client. Authorization credentials and other headers that might be used to
collect data from the client.
11.2. Encoding Sensitive Information in URIs 11.2. Encoding Sensitive Information in URIs
Because the source of a link might be private information or might Because the source of a link might be private information or might
reveal an otherwise private information source, it is strongly reveal an otherwise private information source, it is strongly
recommended that the user be able to select whether or not the recommended that the user be able to select whether or not the
Referer field is sent. For example, a browser client could have a Referer field is sent. For example, a browser client could have a
toggle switch for browsing openly/anonymously, which would toggle switch for browsing openly/anonymously, which would
respectively enable/disable the sending of Referer and From respectively enable/disable the sending of Referer and From
information. information.
Clients SHOULD NOT include a Referer header field in a (non-secure) Clients SHOULD NOT include a Referer header field in a (non-secure)
HTTP request if the referring page was transferred with a secure HTTP request if the referring page was transferred with a secure
protocol. protocol.
Authors of services should not use GET-based forms for the submission Authors of services SHOULD NOT use GET-based forms for the submission
of sensitive data because that data will be encoded in the request- of sensitive data because that data will be placed in the request-
target. Many existing servers, proxies, and user agents log or target. Many existing servers, proxies, and user agents log or
display the request-target in places where it might be visible to display the request-target in places where it might be visible to
third parties. Such services can use POST-based form submission third parties. Such services can use POST-based form submission
instead. instead.
11.3. Location Headers and Spoofing 11.3. Location Headers and Spoofing
If a single server supports multiple organizations that do not trust If a single server supports multiple organizations that do not trust
one another, then it MUST check the values of Location and Content- one another, then it MUST check the values of Location and Content-
Location headers in responses that are generated under control of Location headers in responses that are generated under control of
skipping to change at page 42, line 22 skipping to change at page 42, line 22
12. Acknowledgments 12. Acknowledgments
13. References 13. References
13.1. Normative References 13.1. 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-10 and Message Parsing", draft-ietf-httpbis-p1-messaging-11
(work in progress), July 2010. (work in progress), August 2010.
[Part3] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H., [Part3] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed., Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
and J. Reschke, Ed., "HTTP/1.1, part 3: Message Payload and J. Reschke, Ed., "HTTP/1.1, part 3: Message Payload
and Content Negotiation", draft-ietf-httpbis-p3-payload-10 and Content Negotiation", draft-ietf-httpbis-p3-payload-11
(work in progress), July 2010. (work in progress), August 2010.
[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-10 (work in Requests", draft-ietf-httpbis-p4-conditional-11 (work in
progress), July 2010. progress), August 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-10 (work Partial Responses", draft-ietf-httpbis-p5-range-11 (work
in progress), July 2010. in progress), August 2010.
[Part6] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H., [Part6] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed., Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
Nottingham, M., Ed., and J. Reschke, Ed., "HTTP/1.1, part Nottingham, M., Ed., and J. Reschke, Ed., "HTTP/1.1, part
6: Caching", draft-ietf-httpbis-p6-cache-10 (work in 6: Caching", draft-ietf-httpbis-p6-cache-11 (work in
progress), July 2010. progress), August 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-10 (work in progress), draft-ietf-httpbis-p7-auth-11 (work in progress),
July 2010. August 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.
[RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform [RFC3986] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
Resource Identifier (URI): Generic Syntax", RFC 3986, Resource Identifier (URI): Generic Syntax", RFC 3986,
STD 66, January 2005. STD 66, January 2005.
[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.
skipping to change at page 43, line 43 skipping to change at page 43, line 43
Procedures for Message Header Fields", BCP 90, RFC 3864, Procedures for Message Header Fields", BCP 90, RFC 3864,
September 2004. September 2004.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226, IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008. May 2008.
[RFC5322] Resnick, P., "Internet Message Format", RFC 5322, [RFC5322] Resnick, P., "Internet Message Format", RFC 5322,
October 2008. October 2008.
Appendix A. Compatibility with Previous Versions Appendix A. Changes from RFC 2616
A.1. Changes from RFC 2068
Clarified which error code should be used for inbound server failures
(e.g., DNS failures). (Section 8.5.5).
201 (Created) had a race that required an Etag be sent when a
resource is first created. (Section 8.2.2).
303 (See Also) and 307 (Temporary Redirect) added to address user
agent failure to implement status code 302 properly. (Section 8.3.4
and 8.3.8)
Rewrite of message transmission requirements to make it much harder
for implementors to get it wrong, as the consequences of errors here
can have significant impact on the Internet, and to deal with the
following problems:
1. Changing "HTTP/1.1 or later" to "HTTP/1.1", in contexts where
this was incorrectly placing a requirement on the behavior of an
implementation of a future version of HTTP/1.x
2. Made it clear that user-agents should retry requests, not
"clients" in general.
3. Converted requirements for clients to ignore unexpected 100
(Continue) responses, and for proxies to forward 100 responses,
into a general requirement for 1xx responses.
4. Modified some TCP-specific language, to make it clearer that non-
TCP transports are possible for HTTP.
5. Require that the origin server MUST NOT wait for the request body
before it sends a required 100 (Continue) response.
6. Allow, rather than require, a server to omit 100 (Continue) if it
has already seen some of the request body.
7. Allow servers to defend against denial-of-service attacks and
broken clients.
This change adds the Expect header and 417 status code.
Clean up confusion between 403 and 404 responses. (Section 8.4.4,
8.4.5, and 8.4.11)
The PATCH, LINK, UNLINK methods were defined but not commonly
implemented in previous versions of this specification. See Section
19.6.1 of [RFC2068].
A.2. Changes from RFC 2616
This document takes over the Status Code Registry, previously defined This document takes over the Status Code Registry, previously defined
in Section 7.1 of [RFC2817]. (Section 4.1) in Section 7.1 of [RFC2817]. (Section 4.1)
Clarify definition of POST. (Section 7.5) Clarify definition of POST. (Section 7.5)
Failed to consider that there are many other request methods that are Failed to consider that there are many other request methods that are
safe to automatically redirect, and further that the user agent is safe to automatically redirect, and further that the user agent is
able to make that determination based on the request method able to make that determination based on the request method
semantics. (Sections 8.3.2, 8.3.3 and 8.3.8) semantics. (Sections 8.3.2, 8.3.3 and 8.3.8)
Deprecate 305 Use Proxy status code, because user agents did not Deprecate 305 Use Proxy status code, because user agents did not
implement it. It used to indicate that the requested resource must implement it. It used to indicate that the target resource must be
be accessed through the proxy given by the Location field. The accessed through the proxy given by the Location field. The Location
Location field gave the URI of the proxy. The recipient was expected field gave the URI of the proxy. The recipient was expected to
to repeat this single request via the proxy. (Section 8.3.6) repeat this single request via the proxy. (Section 8.3.6)
Reclassify Allow header as response header, removing the option to Reclassify Allow header as response header, removing the option to
specify it in a PUT request. Relax the server requirement on the specify it in a PUT request. Relax the server requirement on the
contents of the Allow header and remove requirement on clients to contents of the Allow header and remove requirement on clients to
always trust the header value. (Section 9.1) always trust the header value. (Section 9.1)
Correct syntax of Location header to allow URI references (including Correct syntax of Location header to allow URI references (including
relative references and fragments), as referred symbol "absoluteURI" relative references and fragments), as referred symbol "absoluteURI"
wasn't what was expected, and add some clarifications as to when use wasn't what was expected, and add some clarifications as to when use
of fragments would not be appropriate. (Section 9.4) of fragments would not be appropriate. (Section 9.4)
skipping to change at page 45, line 35 skipping to change at page 44, line 33
Allow Referer value of "about:blank" as alternative to not specifying Allow Referer value of "about:blank" as alternative to not specifying
it. (Section 9.6) it. (Section 9.6)
In the description of the Server header, the Via field was described In the description of the Server header, the Via field was described
as a SHOULD. The requirement was and is stated correctly in the as a SHOULD. The requirement was and is stated correctly in the
description of the Via header in Section 9.9 of [Part1]. description of the Via header in Section 9.9 of [Part1].
(Section 9.8) (Section 9.8)
Appendix B. Collected ABNF Appendix B. Collected ABNF
Accept = <Accept, defined in [Part3], Section 5.1> Accept = <Accept, defined in [Part3], Section 6.1>
Accept-Charset = <Accept-Charset, defined in [Part3], Section 5.2> Accept-Charset = <Accept-Charset, defined in [Part3], Section 6.2>
Accept-Encoding = <Accept-Encoding, defined in [Part3], Section 5.3> Accept-Encoding = <Accept-Encoding, defined in [Part3], Section 6.3>
Accept-Language = <Accept-Language, defined in [Part3], Section 5.4> Accept-Language = <Accept-Language, defined in [Part3], Section 6.4>
Accept-Ranges = <Accept-Ranges, defined in [Part5], Section 5.1> Accept-Ranges = <Accept-Ranges, defined in [Part5], Section 5.1>
Age = <Age, defined in [Part6], Section 3.1> Age = <Age, defined in [Part6], Section 3.1>
Allow = "Allow:" OWS Allow-v Allow = "Allow:" OWS Allow-v
Allow-v = [ ( "," / Method ) *( OWS "," [ OWS Method ] ) ] Allow-v = [ ( "," / Method ) *( OWS "," [ OWS Method ] ) ]
Authorization = <Authorization, defined in [Part7], Section 3.1> Authorization = <Authorization, defined in [Part7], Section 3.1>
ETag = <ETag, defined in [Part4], Section 6.1> ETag = <ETag, defined in [Part4], Section 6.1>
Expect = "Expect:" OWS Expect-v Expect = "Expect:" OWS Expect-v
Expect-v = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] ) Expect-v = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] )
skipping to change at page 52, line 42 skipping to change at page 51, line 36
combination / precedence during redirects" combination / precedence during redirects"
Partly resolved issues: Partly resolved issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/185>: "Location o <http://tools.ietf.org/wg/httpbis/trac/ticket/185>: "Location
header payload handling" header payload handling"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/196>: "Term for the o <http://tools.ietf.org/wg/httpbis/trac/ticket/196>: "Term for the
requested resource's URI" requested resource's URI"
C.12. Since draft-ietf-httpbis-p2-semantics-10
Closed issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/69>: "Clarify
'Requested Variant'"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/109>: "Clarify
entity / representation / variant terminology"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/139>: "Methods and
Caching"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/190>: "OPTIONS vs
Max-Forwards"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/199>: "Status codes
and caching"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/220>: "consider
removing the 'changes from 2068' sections"
Index Index
1 1
100 Continue (status code) 20 100 Continue (status code) 20
101 Switching Protocols (status code) 20 101 Switching Protocols (status code) 21
2 2
200 OK (status code) 21 200 OK (status code) 21
201 Created (status code) 21 201 Created (status code) 21
202 Accepted (status code) 22 202 Accepted (status code) 22
203 Non-Authoritative Information (status code) 22 203 Non-Authoritative Information (status code) 22
204 No Content (status code) 22 204 No Content (status code) 22
205 Reset Content (status code) 23 205 Reset Content (status code) 23
206 Partial Content (status code) 23 206 Partial Content (status code) 23
3 3
300 Multiple Choices (status code) 23 300 Multiple Choices (status code) 24
301 Moved Permanently (status code) 24 301 Moved Permanently (status code) 24
302 Found (status code) 24 302 Found (status code) 25
303 See Other (status code) 25 303 See Other (status code) 25
304 Not Modified (status code) 25 304 Not Modified (status code) 26
305 Use Proxy (status code) 26 305 Use Proxy (status code) 26
306 (Unused) (status code) 26 306 (Unused) (status code) 26
307 Temporary Redirect (status code) 26 307 Temporary Redirect (status code) 26
4 4
400 Bad Request (status code) 27 400 Bad Request (status code) 27
401 Unauthorized (status code) 27 401 Unauthorized (status code) 27
402 Payment Required (status code) 27 402 Payment Required (status code) 27
403 Forbidden (status code) 27 403 Forbidden (status code) 27
404 Not Found (status code) 27 404 Not Found (status code) 28
405 Method Not Allowed (status code) 27 405 Method Not Allowed (status code) 28
406 Not Acceptable (status code) 28 406 Not Acceptable (status code) 28
407 Proxy Authentication Required (status code) 28 407 Proxy Authentication Required (status code) 28
408 Request Timeout (status code) 28 408 Request Timeout (status code) 29
409 Conflict (status code) 28 409 Conflict (status code) 29
410 Gone (status code) 29 410 Gone (status code) 29
411 Length Required (status code) 29 411 Length Required (status code) 30
412 Precondition Failed (status code) 29 412 Precondition Failed (status code) 30
413 Request Entity Too Large (status code) 29 413 Request Entity Too Large (status code) 30
414 URI Too Long (status code) 30 414 URI Too Long (status code) 30
415 Unsupported Media Type (status code) 30 415 Unsupported Media Type (status code) 30
416 Requested Range Not Satisfiable (status code) 30 416 Requested Range Not Satisfiable (status code) 30
417 Expectation Failed (status code) 30 417 Expectation Failed (status code) 31
5 5
500 Internal Server Error (status code) 31 500 Internal Server Error (status code) 31
501 Not Implemented (status code) 31 501 Not Implemented (status code) 31
502 Bad Gateway (status code) 31 502 Bad Gateway (status code) 31
503 Service Unavailable (status code) 31 503 Service Unavailable (status code) 31
504 Gateway Timeout (status code) 31 504 Gateway Timeout (status code) 32
505 HTTP Version Not Supported (status code) 31 505 HTTP Version Not Supported (status code) 32
A A
Allow header 32 Allow header 32
C C
CONNECT method 20 CONNECT method 20
D D
DELETE method 19 DELETE method 19
E E
Expect header 32 Expect header 33
F F
From header 33 From header 33
G G
GET method 16 GET method 16
Grammar Grammar
Allow 32 Allow 32
Allow-v 32 Allow-v 32
delta-seconds 36 delta-seconds 37
Expect 32 Expect 33
expect-params 32 expect-params 33
Expect-v 32 Expect-v 33
expectation 32 expectation 33
expectation-extension 32 expectation-extension 33
extension-code 11 extension-code 11
extension-method 8 extension-method 8
From 33 From 34
From-v 33 From-v 34
Location 34 Location 34
Location-v 34 Location-v 34
Max-Forwards 35 Max-Forwards 35
Max-Forwards-v 35 Max-Forwards-v 35
Method 8 Method 8
Reason-Phrase 11 Reason-Phrase 11
Referer 36 Referer 36
Referer-v 36 Referer-v 36
request-header 9 request-header 9
response-header 12 response-header 12
Retry-After 36 Retry-After 36
Retry-After-v 36 Retry-After-v 36
Server 37 Server 37
Server-v 37 Server-v 37
Status-Code 11 Status-Code 11
User-Agent 37 User-Agent 38
User-Agent-v 37 User-Agent-v 38
H H
HEAD method 16 HEAD method 16
Headers Headers
Allow 32 Allow 32
Expect 32 Expect 33
From 33 From 33
Location 34 Location 34
Max-Forwards 35 Max-Forwards 35
Referer 35 Referer 36
Retry-After 36 Retry-After 36
Server 37 Server 37
User-Agent 37 User-Agent 37
I I
Idempotent Methods 14 Idempotent Methods 14
L L
LINK method 44
Location header 34 Location header 34
M M
Max-Forwards header 35 Max-Forwards header 35
Methods Methods
CONNECT 20 CONNECT 20
DELETE 19 DELETE 19
GET 16 GET 16
HEAD 16 HEAD 16
LINK 44 OPTIONS 15
OPTIONS 14
PATCH 44
POST 17 POST 17
PUT 17 PUT 18
TRACE 19 TRACE 19
UNLINK 44
O O
OPTIONS method 14 OPTIONS method 15
P P
PATCH method 44
POST method 17 POST method 17
PUT method 17 PUT method 18
R R
Referer header 35 Referer header 36
Retry-After header 36 Retry-After header 36
S S
Safe Methods 14 Safe Methods 14
Server header 37 Server header 37
Status Codes Status Codes
100 Continue 20 100 Continue 20
101 Switching Protocols 20 101 Switching Protocols 21
200 OK 21 200 OK 21
201 Created 21 201 Created 21
202 Accepted 22 202 Accepted 22
203 Non-Authoritative Information 22 203 Non-Authoritative Information 22
204 No Content 22 204 No Content 22
205 Reset Content 23 205 Reset Content 23
206 Partial Content 23 206 Partial Content 23
300 Multiple Choices 23 300 Multiple Choices 24
301 Moved Permanently 24 301 Moved Permanently 24
302 Found 24 302 Found 25
303 See Other 25 303 See Other 25
304 Not Modified 25 304 Not Modified 26
305 Use Proxy 26 305 Use Proxy 26
306 (Unused) 26 306 (Unused) 26
307 Temporary Redirect 26 307 Temporary Redirect 26
400 Bad Request 27 400 Bad Request 27
401 Unauthorized 27 401 Unauthorized 27
402 Payment Required 27 402 Payment Required 27
403 Forbidden 27 403 Forbidden 27
404 Not Found 27 404 Not Found 28
405 Method Not Allowed 27 405 Method Not Allowed 28
406 Not Acceptable 28 406 Not Acceptable 28
407 Proxy Authentication Required 28 407 Proxy Authentication Required 28
408 Request Timeout 28 408 Request Timeout 29
409 Conflict 28 409 Conflict 29
410 Gone 29 410 Gone 29
411 Length Required 29 411 Length Required 30
412 Precondition Failed 29 412 Precondition Failed 30
413 Request Entity Too Large 29 413 Request Entity Too Large 30
414 URI Too Long 30 414 URI Too Long 30
415 Unsupported Media Type 30 415 Unsupported Media Type 30
416 Requested Range Not Satisfiable 30 416 Requested Range Not Satisfiable 30
417 Expectation Failed 30 417 Expectation Failed 31
500 Internal Server Error 31 500 Internal Server Error 31
501 Not Implemented 31 501 Not Implemented 31
502 Bad Gateway 31 502 Bad Gateway 31
503 Service Unavailable 31 503 Service Unavailable 31
504 Gateway Timeout 31 504 Gateway Timeout 32
505 HTTP Version Not Supported 31 505 HTTP Version Not Supported 32
T T
TRACE method 19 TRACE method 19
U U
UNLINK method 44
User-Agent header 37 User-Agent header 37
Authors' Addresses Authors' Addresses
Roy T. Fielding (editor) Roy T. Fielding (editor)
Day Software Day Software
23 Corporate Plaza DR, Suite 280 23 Corporate Plaza DR, Suite 280
Newport Beach, CA 92660 Newport Beach, CA 92660
USA USA
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