source: draft-ietf-httpbis/latest/p2-semantics.xml @ 1335

Last change on this file since 1335 was 1335, checked in by julian.reschke@…, 8 years ago

Tune strength of requirements on Accept re: 406 (see #285)

  • Property svn:eol-style set to native
File size: 170.1 KB
Line 
1<?xml version="1.0" encoding="utf-8"?>
2<?xml-stylesheet type='text/xsl' href='../myxml2rfc.xslt'?>
3<!DOCTYPE rfc [
4  <!ENTITY MAY "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MAY</bcp14>">
5  <!ENTITY MUST "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST</bcp14>">
6  <!ENTITY MUST-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST NOT</bcp14>">
7  <!ENTITY OPTIONAL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>OPTIONAL</bcp14>">
8  <!ENTITY RECOMMENDED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>RECOMMENDED</bcp14>">
9  <!ENTITY REQUIRED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>REQUIRED</bcp14>">
10  <!ENTITY SHALL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL</bcp14>">
11  <!ENTITY SHALL-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL NOT</bcp14>">
12  <!ENTITY SHOULD "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD</bcp14>">
13  <!ENTITY SHOULD-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD NOT</bcp14>">
14  <!ENTITY ID-VERSION "latest">
15  <!ENTITY ID-MONTH "July">
16  <!ENTITY ID-YEAR "2011">
17  <!ENTITY mdash "&#8212;">
18  <!ENTITY notation                   "<xref target='Part1' x:rel='#notation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
19  <!ENTITY messaging                  "<xref target='Part1' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
20  <!ENTITY payload                    "<xref target='Part3' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
21  <!ENTITY conditional                "<xref target='Part4' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
22  <!ENTITY range                      "<xref target='Part5' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
23  <!ENTITY caching                    "<xref target='Part6' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
24  <!ENTITY auth                       "<xref target='Part7' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
25  <!ENTITY combining-responses        "<xref target='Part6' x:rel='#combining.responses' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
26  <!ENTITY content-negotiation        "<xref target='Part3' x:rel='#content.negotiation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
27  <!ENTITY notation-abnf              "<xref target='Part1' x:rel='#notation.abnf' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
28  <!ENTITY basic-rules                "<xref target='Part1' x:rel='#basic.rules' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
29  <!ENTITY uri                        "<xref target='Part1' x:rel='#uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
30  <!ENTITY effective-request-uri      "<xref target='Part1' x:rel='#effective.request.uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
31  <!ENTITY intermediaries             "<xref target='Part1' x:rel='#intermediaries' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
32  <!ENTITY full-date                  "<xref target='Part1' x:rel='#date.time.formats.full.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
33  <!ENTITY http-url                   "<xref target='Part1' x:rel='#http-url' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
34  <!ENTITY http-version               "<xref target='Part1' x:rel='#http.version' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
35  <!ENTITY use100                     "<xref target='Part1' x:rel='#use.of.the.100.status' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
36  <!ENTITY qvalue                     "<xref target='Part3' x:rel='#quality.values' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
37  <!ENTITY request-target             "<xref target='Part1' x:rel='#request-target' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
38  <!ENTITY header-accept              "<xref target='Part3' x:rel='#header.accept' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
39  <!ENTITY header-accept-charset      "<xref target='Part3' x:rel='#header.accept-charset' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
40  <!ENTITY header-accept-encoding     "<xref target='Part3' x:rel='#header.accept-encoding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
41  <!ENTITY header-accept-language     "<xref target='Part3' x:rel='#header.accept-language' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
42  <!ENTITY header-accept-ranges       "<xref target='Part5' x:rel='#header.accept-ranges' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
43  <!ENTITY header-age                 "<xref target='Part6' x:rel='#header.age' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
44  <!ENTITY header-authorization       "<xref target='Part7' x:rel='#header.authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
45  <!ENTITY header-cache-control       "<xref target='Part6' x:rel='#header.cache-control' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
46  <!ENTITY header-content-location    "<xref target='Part3' x:rel='#header.content-location' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
47  <!ENTITY header-content-range       "<xref target='Part5' x:rel='#header.content-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
48  <!ENTITY header-etag                "<xref target='Part4' x:rel='#header.etag' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
49  <!ENTITY header-expires             "<xref target='Part6' x:rel='#header.expires' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
50  <!ENTITY header-fields              "<xref target='Part1' x:rel='#header.fields' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
51  <!ENTITY header-host                "<xref target='Part1' x:rel='#header.host' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
52  <!ENTITY header-if-match            "<xref target='Part4' x:rel='#header.if-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
53  <!ENTITY header-if-modified-since   "<xref target='Part4' x:rel='#header.if-modified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
54  <!ENTITY header-if-none-match       "<xref target='Part4' x:rel='#header.if-none-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
55  <!ENTITY header-if-range            "<xref target='Part5' x:rel='#header.if-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
56  <!ENTITY header-if-unmodified-since "<xref target='Part4' x:rel='#header.if-unmodified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
57  <!ENTITY header-pragma              "<xref target='Part6' x:rel='#header.pragma' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
58  <!ENTITY header-proxy-authenticate  "<xref target='Part7' x:rel='#header.proxy-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
59  <!ENTITY header-proxy-authorization "<xref target='Part7' x:rel='#header.proxy-authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
60  <!ENTITY header-range               "<xref target='Part5' x:rel='#header.range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
61  <!ENTITY header-upgrade             "<xref target='Part1' x:rel='#header.upgrade' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
62  <!ENTITY header-te                  "<xref target='Part1' x:rel='#header.te' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
63  <!ENTITY header-vary                "<xref target='Part6' x:rel='#header.vary' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
64  <!ENTITY header-via                 "<xref target='Part1' x:rel='#header.via' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
65  <!ENTITY header-warning             "<xref target='Part6' x:rel='#header.warning' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
66  <!ENTITY header-www-authenticate    "<xref target='Part7' x:rel='#header.www-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
67  <!ENTITY message-body               "<xref target='Part1' x:rel='#message.body' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
68  <!ENTITY product-tokens             "<xref target='Part1' x:rel='#product.tokens' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
69  <!ENTITY media-type-message-http    "<xref target='Part1' x:rel='#internet.media.type.message.http' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
70  <!ENTITY status-206                 "<xref target='Part5' x:rel='#status.206' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
71  <!ENTITY status-304                 "<xref target='Part4' x:rel='#status.304' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
72  <!ENTITY status-401                 "<xref target='Part7' x:rel='#status.401' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
73  <!ENTITY status-407                 "<xref target='Part7' x:rel='#status.407' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
74  <!ENTITY status-412                 "<xref target='Part4' x:rel='#status.412' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
75  <!ENTITY status-416                 "<xref target='Part5' x:rel='#status.416' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
76  <!ENTITY p3-header-fields           "<xref target='Part3' x:rel='#header.fields' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
77  <!ENTITY p4-status-codes            "<xref target='Part4' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
78  <!ENTITY p5-status-codes            "<xref target='Part5' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
79  <!ENTITY p7-status-codes            "<xref target='Part7' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
80  <!ENTITY p6-heuristic               "<xref target='Part6' x:rel='#heuristic.freshness' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
81  <!ENTITY p6-explicit                "<xref target='Part6' x:rel='#calculating.freshness.lifetime' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
82  <!ENTITY p6-invalid                 "<xref target='Part6' x:rel='#invalidation.after.updates.or.deletions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
83]>
84<?rfc toc="yes" ?>
85<?rfc symrefs="yes" ?>
86<?rfc sortrefs="yes" ?>
87<?rfc compact="yes"?>
88<?rfc subcompact="no" ?>
89<?rfc linkmailto="no" ?>
90<?rfc editing="no" ?>
91<?rfc comments="yes"?>
92<?rfc inline="yes"?>
93<?rfc rfcedstyle="yes"?>
94<?rfc-ext allow-markup-in-artwork="yes" ?>
95<?rfc-ext include-references-in-index="yes" ?>
96<rfc obsoletes="2616" updates="2817" category="std" x:maturity-level="draft"
97     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"
98     xmlns:x='http://purl.org/net/xml2rfc/ext'
99     xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
100<front>
101
102  <title abbrev="HTTP/1.1, Part 2">HTTP/1.1, part 2: Message Semantics</title>
103
104  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
105    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
106    <address>
107      <postal>
108        <street>345 Park Ave</street>
109        <city>San Jose</city>
110        <region>CA</region>
111        <code>95110</code>
112        <country>USA</country>
113      </postal>
114      <email>fielding@gbiv.com</email>
115      <uri>http://roy.gbiv.com/</uri>
116    </address>
117  </author>
118
119  <author initials="J." surname="Gettys" fullname="Jim Gettys">
120    <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
121    <address>
122      <postal>
123        <street>21 Oak Knoll Road</street>
124        <city>Carlisle</city>
125        <region>MA</region>
126        <code>01741</code>
127        <country>USA</country>
128      </postal>
129      <email>jg@freedesktop.org</email>
130      <uri>http://gettys.wordpress.com/</uri>
131    </address>
132  </author>
133 
134  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
135    <organization abbrev="HP">Hewlett-Packard Company</organization>
136    <address>
137      <postal>
138        <street>HP Labs, Large Scale Systems Group</street>
139        <street>1501 Page Mill Road, MS 1177</street>
140        <city>Palo Alto</city>
141        <region>CA</region>
142        <code>94304</code>
143        <country>USA</country>
144      </postal>
145      <email>JeffMogul@acm.org</email>
146    </address>
147  </author>
148
149  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
150    <organization abbrev="Microsoft">Microsoft Corporation</organization>
151    <address>
152      <postal>
153        <street>1 Microsoft Way</street>
154        <city>Redmond</city>
155        <region>WA</region>
156        <code>98052</code>
157        <country>USA</country>
158      </postal>
159      <email>henrikn@microsoft.com</email>
160    </address>
161  </author>
162
163  <author initials="L." surname="Masinter" fullname="Larry Masinter">
164    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
165    <address>
166      <postal>
167        <street>345 Park Ave</street>
168        <city>San Jose</city>
169        <region>CA</region>
170        <code>95110</code>
171        <country>USA</country>
172      </postal>
173      <email>LMM@acm.org</email>
174      <uri>http://larry.masinter.net/</uri>
175    </address>
176  </author>
177 
178  <author initials="P." surname="Leach" fullname="Paul J. Leach">
179    <organization abbrev="Microsoft">Microsoft Corporation</organization>
180    <address>
181      <postal>
182        <street>1 Microsoft Way</street>
183        <city>Redmond</city>
184        <region>WA</region>
185        <code>98052</code>
186      </postal>
187      <email>paulle@microsoft.com</email>
188    </address>
189  </author>
190   
191  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
192    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
193    <address>
194      <postal>
195        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
196        <street>The Stata Center, Building 32</street>
197        <street>32 Vassar Street</street>
198        <city>Cambridge</city>
199        <region>MA</region>
200        <code>02139</code>
201        <country>USA</country>
202      </postal>
203      <email>timbl@w3.org</email>
204      <uri>http://www.w3.org/People/Berners-Lee/</uri>
205    </address>
206  </author>
207
208  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
209    <organization abbrev="W3C">World Wide Web Consortium</organization>
210    <address>
211      <postal>
212        <street>W3C / ERCIM</street>
213        <street>2004, rte des Lucioles</street>
214        <city>Sophia-Antipolis</city>
215        <region>AM</region>
216        <code>06902</code>
217        <country>France</country>
218      </postal>
219      <email>ylafon@w3.org</email>
220      <uri>http://www.raubacapeu.net/people/yves/</uri>
221    </address>
222  </author>
223
224  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
225    <organization abbrev="greenbytes">greenbytes GmbH</organization>
226    <address>
227      <postal>
228        <street>Hafenweg 16</street>
229        <city>Muenster</city><region>NW</region><code>48155</code>
230        <country>Germany</country>
231      </postal>
232      <phone>+49 251 2807760</phone>
233      <facsimile>+49 251 2807761</facsimile>
234      <email>julian.reschke@greenbytes.de</email>
235      <uri>http://greenbytes.de/tech/webdav/</uri>
236    </address>
237  </author>
238
239  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
240  <workgroup>HTTPbis Working Group</workgroup>
241
242<abstract>
243<t>
244   The Hypertext Transfer Protocol (HTTP) is an application-level
245   protocol for distributed, collaborative, hypermedia information
246   systems. HTTP has been in use by the World Wide Web global information
247   initiative since 1990. This document is Part 2 of the seven-part specification
248   that defines the protocol referred to as "HTTP/1.1" and, taken together,
249   obsoletes RFC 2616.  Part 2 defines the semantics of HTTP messages
250   as expressed by request methods, request header fields, response status codes,
251   and response header fields.
252</t>
253</abstract>
254
255<note title="Editorial Note (To be removed by RFC Editor)">
256  <t>
257    Discussion of this draft should take place on the HTTPBIS working group
258    mailing list (ietf-http-wg@w3.org), which is archived at
259    <eref target="http://lists.w3.org/Archives/Public/ietf-http-wg/"/>.
260  </t>
261  <t>
262    The current issues list is at
263    <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/> and related
264    documents (including fancy diffs) can be found at
265    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
266  </t>
267  <t>
268    The changes in this draft are summarized in <xref target="changes.since.15"/>.
269  </t>
270</note>
271</front>
272<middle>
273<section title="Introduction" anchor="introduction">
274<t>
275   This document defines HTTP/1.1 request and response semantics.  Each HTTP
276   message, as defined in &messaging;, is in the form of either a request or
277   a response.  An HTTP server listens on a connection for HTTP requests and
278   responds to each request, in the order received on that connection, with
279   one or more HTTP response messages.  This document defines the commonly
280   agreed upon semantics of the HTTP uniform interface, the intentions defined
281   by each request method, and the various response messages that might be
282   expected as a result of applying that method to the target resource.
283</t>
284<t>
285   This document is currently disorganized in order to minimize the changes
286   between drafts and enable reviewers to see the smaller errata changes.
287   A future draft will reorganize the sections to better reflect the content.
288   In particular, the sections will be ordered according to the typical
289   processing of an HTTP request message (after message parsing): resource
290   mapping, methods, request modifying header fields, response status,
291   status modifying header fields, and resource metadata.  The current mess
292   reflects how widely dispersed these topics and associated requirements
293   had become in <xref target="RFC2616"/>.
294</t>
295
296<section title="Requirements" anchor="intro.requirements">
297<t>
298   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
299   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
300   document are to be interpreted as described in <xref target="RFC2119"/>.
301</t>
302<t>
303   An implementation is not compliant if it fails to satisfy one or more
304   of the "MUST" or "REQUIRED" level requirements for the protocols it
305   implements. An implementation that satisfies all the "MUST" or "REQUIRED"
306   level and all the "SHOULD" level requirements for its protocols is said
307   to be "unconditionally compliant"; one that satisfies all the "MUST"
308   level requirements but not all the "SHOULD" level requirements for its
309   protocols is said to be "conditionally compliant".
310</t>
311</section>
312
313<section title="Syntax Notation" anchor="notation">
314  <x:anchor-alias value="CR"/>
315  <x:anchor-alias value="DIGIT"/>
316  <x:anchor-alias value="LF"/>
317  <x:anchor-alias value="VCHAR"/>
318  <x:anchor-alias value="WSP"/>
319<t>
320  This specification uses the ABNF syntax defined in &notation; (which
321  extends the syntax defined in <xref target="RFC5234"/> with a list rule).
322  <xref target="collected.abnf"/> shows the collected ABNF, with the list
323  rule expanded.
324</t>
325<t>
326  The following core rules are included by
327  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
328  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
329  DIGIT (decimal 0-9), DQUOTE (double quote),
330  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
331  OCTET (any 8-bit sequence of data), SP (space),
332  VCHAR (any visible USASCII character),
333  and WSP (whitespace).
334</t>
335
336<section title="Core Rules" anchor="core.rules">
337  <x:anchor-alias value="obs-text"/>
338  <x:anchor-alias value="quoted-string"/>
339  <x:anchor-alias value="token"/>
340  <x:anchor-alias value="OWS"/>
341  <x:anchor-alias value="RWS"/>
342<t>
343  The core rules below are defined in &basic-rules;:
344</t>
345<figure><artwork type="abnf2616">
346  <x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in &basic-rules;&gt;
347  <x:ref>token</x:ref>         = &lt;token, defined in &basic-rules;&gt;
348  <x:ref>OWS</x:ref>           = &lt;OWS, defined in &basic-rules;&gt;
349  <x:ref>RWS</x:ref>           = &lt;RWS, defined in &basic-rules;&gt;
350  <x:ref>obs-text</x:ref>      = &lt;obs-text, defined in &basic-rules;&gt;
351</artwork></figure>
352</section>
353
354<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
355  <x:anchor-alias value="absolute-URI"/>
356  <x:anchor-alias value="comment"/>
357  <x:anchor-alias value="HTTP-date"/>
358  <x:anchor-alias value="partial-URI"/>
359  <x:anchor-alias value="product"/>
360  <x:anchor-alias value="URI-reference"/>
361<t>
362  The ABNF rules below are defined in other parts:
363</t>
364<figure><!--Part1--><artwork type="abnf2616">
365  <x:ref>absolute-URI</x:ref>  = &lt;absolute-URI, defined in &uri;&gt;
366  <x:ref>comment</x:ref>       = &lt;comment, defined in &header-fields;&gt;
367  <x:ref>HTTP-date</x:ref>     = &lt;HTTP-date, defined in &full-date;&gt;
368  <x:ref>partial-URI</x:ref>   = &lt;partial-URI, defined in &uri;&gt;
369  <x:ref>product</x:ref>       = &lt;product, defined in &product-tokens;&gt;
370  <x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in &uri;&gt;
371</artwork></figure>
372</section>
373</section>
374</section>
375
376<section title="Method" anchor="method">
377  <x:anchor-alias value="Method"/>
378  <x:anchor-alias value="extension-method"/>
379<t>
380   The Method token indicates the request method to be performed on the target
381   resource (&effective-request-uri;). The method is case-sensitive.
382</t>
383<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Method"/>
384  <x:ref>Method</x:ref>         = <x:ref>token</x:ref>
385</artwork></figure>
386<t>
387   The list of methods allowed by a resource can be specified in an
388   Allow header field (<xref target="header.allow"/>). The status code of the response
389   always notifies the client whether a method is currently allowed on a
390   resource, since the set of allowed methods can change dynamically. An
391   origin server &SHOULD; respond with the status code 405 (Method Not Allowed)
392   if the method is known by the origin server but not allowed for the
393   resource, and 501 (Not Implemented) if the method is
394   unrecognized or not implemented by the origin server. The methods GET
395   and HEAD &MUST; be supported by all general-purpose servers. All other
396   methods are &OPTIONAL;; however, if the above methods are implemented,
397   they &MUST; be implemented with the same semantics as those specified
398   in <xref target="method.definitions"/>.
399</t>
400
401<section title="Overview of Methods" anchor="overview.of.methods">
402<t>
403  The methods listed below are defined in <xref target="method.definitions"/>.
404</t>
405<texttable align="left">
406  <ttcol>Method Name</ttcol><ttcol>Defined in...</ttcol>
407 
408  <c>OPTIONS</c> <c><xref target="OPTIONS"/></c>
409  <c>GET</c> <c><xref target="GET"/></c>
410  <c>HEAD</c> <c><xref target="HEAD"/></c>
411  <c>POST</c> <c><xref target="POST"/></c>
412  <c>PUT</c> <c><xref target="PUT"/></c>
413  <c>DELETE</c> <c><xref target="DELETE"/></c>
414  <c>TRACE</c> <c><xref target="TRACE"/></c>
415  <c>CONNECT</c> <c><xref target="CONNECT"/></c>
416</texttable>
417<t>
418  Note that this list is not exhaustive &mdash; it does not include request methods defined
419  in other specifications.
420</t>
421</section>
422
423<section title="Method Registry" anchor="method.registry">
424<t>
425  The HTTP Method Registry defines the name space for the Method token in the
426  Request line of an HTTP request.
427</t>
428<t>
429  Registrations &MUST; include the following fields:
430  <list style="symbols">
431    <t>Method Name (see <xref target="method"/>)</t>
432    <t>Safe ("yes" or "no", see <xref target="safe.methods"/>)</t>
433    <t>Pointer to specification text</t>
434  </list>
435</t>
436<t>
437  Values to be added to this name space are subject to IETF review
438  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
439</t>
440<t>
441  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-methods"/>.
442</t>
443
444<section title="Considerations for New Methods" anchor="considerations.for.new.methods">
445<t>
446   When it is necessary to express new semantics for a HTTP request that
447   aren't specific to a single application or media type, and currently defined
448   methods are inadequate, it may be appropriate to register a new method.
449</t>
450<t>
451   HTTP methods are generic; that is, they are potentially applicable to any
452   resource, not just one particular media type, "type" of resource, or
453   application. As such, it is preferred that new HTTP methods be registered
454   in a document that isn't specific to a single application, so that this is
455   clear.
456</t>
457<t>
458   Due to the parsing rules defined in &message-body;, definitions of HTTP
459   methods cannot prohibit the presence of a message-body on either the request
460   or the response message (with responses to HEAD requests being the single
461   exception). Definitions of new methods cannot change this rule, but they can
462   specify that only zero-length bodies (as opposed to absent bodies) are allowed.
463</t>
464<t>
465   New method definitions need to indicate whether they are safe (<xref
466   target="safe.methods"/>), what semantics (if any) the request body has,
467   and whether they are idempotent (<xref target="idempotent.methods"/>).
468   They also need to state whether they can be cached (&caching;); in
469   particular what conditions a cache may store the response, and under what
470   conditions such a stored response may be used to satisfy a subsequent
471   request.
472</t>
473</section>
474
475</section>
476</section>
477
478<section title="Request Header Fields" anchor="request.header.fields">
479  <x:anchor-alias value="request-header"/>
480<t>
481   The request header fields allow the client to pass additional
482   information about the request, and about the client itself, to the
483   server. These fields act as request modifiers, with semantics
484   equivalent to the parameters on a programming language method
485   invocation.
486</t>
487<texttable align="left">
488  <ttcol>Header Field Name</ttcol>
489  <ttcol>Defined in...</ttcol>
490
491  <c>Accept</c> <c>&header-accept;</c>
492  <c>Accept-Charset</c> <c>&header-accept-charset;</c>
493  <c>Accept-Encoding</c> <c>&header-accept-encoding;</c>
494  <c>Accept-Language</c> <c>&header-accept-language;</c>
495  <c>Authorization</c> <c>&header-authorization;</c>
496  <c>Expect</c> <c><xref target="header.expect"/></c>
497  <c>From</c> <c><xref target="header.from"/></c>
498  <c>Host</c> <c>&header-host;</c>
499  <c>If-Match</c> <c>&header-if-match;</c>
500  <c>If-Modified-Since</c> <c>&header-if-modified-since;</c>
501  <c>If-None-Match</c> <c>&header-if-none-match;</c>
502  <c>If-Range</c> <c>&header-if-range;</c>
503  <c>If-Unmodified-Since</c> <c>&header-if-unmodified-since;</c>
504  <c>Max-Forwards</c> <c><xref target="header.max-forwards"/></c>
505  <c>Proxy-Authorization</c> <c>&header-proxy-authorization;</c>
506  <c>Range</c> <c>&header-range;</c>
507  <c>Referer</c> <c><xref target="header.referer"/></c>
508  <c>TE</c> <c>&header-te;</c>
509  <c>User-Agent</c> <c><xref target="header.user-agent"/></c>
510</texttable>
511</section>
512
513<section title="Status Code and Reason Phrase" anchor="status.code.and.reason.phrase">
514  <x:anchor-alias value="Reason-Phrase"/>
515  <x:anchor-alias value="Status-Code"/>
516  <x:anchor-alias value="extension-code"/>
517<t>
518   The Status-Code element is a 3-digit integer result code of the attempt to
519   understand and satisfy the request.
520</t>
521<t>
522   The Reason-Phrase is intended to give a short textual description of the
523   Status-Code and is intended for a human user. The client does not need
524   to examine or display the Reason-Phrase.
525</t>
526<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Status-Code"/><iref primary="true" item="Grammar" subitem="extension-code"/><iref primary="true" item="Grammar" subitem="Reason-Phrase"/>
527  <x:ref>Status-Code</x:ref>    = 3<x:ref>DIGIT</x:ref>
528  <x:ref>Reason-Phrase</x:ref>  = *( <x:ref>WSP</x:ref> / <x:ref>VCHAR</x:ref> / <x:ref>obs-text</x:ref> )
529</artwork></figure>
530<t>
531   HTTP status codes are extensible. HTTP applications are not required
532   to understand the meaning of all registered status codes, though such
533   understanding is obviously desirable. However, applications &MUST;
534   understand the class of any status code, as indicated by the first
535   digit, and treat any unrecognized response as being equivalent to the
536   x00 status code of that class, with the exception that an
537   unrecognized response &MUST-NOT; be cached. For example, if an
538   unrecognized status code of 431 is received by the client, it can
539   safely assume that there was something wrong with its request and
540   treat the response as if it had received a 400 status code. In such
541   cases, user agents &SHOULD; present to the user the representation enclosed
542   with the response, since that representation is likely to include human-readable
543   information which will explain the unusual status.
544</t>
545
546<section title="Overview of Status Codes" anchor="overview.of.status.codes">
547<t> 
548   The status codes listed below are defined in <xref target="status.codes"/>
549   of this specification, &p4-status-codes;, &p5-status-codes;, and &p7-status-codes;.
550   The reason phrases listed here are only recommendations &mdash; they can be
551   replaced by local equivalents without affecting the protocol.
552</t>
553<texttable align="left">
554  <ttcol>Status-Code</ttcol>
555  <ttcol>Reason-Phrase</ttcol>
556  <ttcol>Defined in...</ttcol>
557 
558  <c>100</c> <c>Continue</c> <c><xref target="status.100"/></c>
559  <c>101</c> <c>Switching Protocols</c> <c><xref target="status.101"/></c>
560
561  <c>200</c> <c>OK</c> <c><xref target="status.200"/></c>
562  <c>201</c> <c>Created</c> <c><xref target="status.201"/></c>
563  <c>202</c> <c>Accepted</c> <c><xref target="status.202"/></c>
564  <c>203</c> <c>Non-Authoritative Information</c> <c><xref target="status.203"/></c>
565  <c>204</c> <c>No Content</c> <c><xref target="status.204"/></c>
566  <c>205</c> <c>Reset Content</c> <c><xref target="status.205"/></c>
567  <c>206</c> <c>Partial Content</c> <c>&status-206;</c>
568
569  <c>300</c> <c>Multiple Choices</c> <c><xref target="status.300"/></c>
570  <c>301</c> <c>Moved Permanently</c> <c><xref target="status.301"/></c>
571  <c>302</c> <c>Found</c> <c><xref target="status.302"/></c>
572  <c>303</c> <c>See Other</c> <c><xref target="status.303"/></c>
573  <c>304</c> <c>Not Modified</c> <c>&status-304;</c>
574  <c>305</c> <c>Use Proxy</c> <c><xref target="status.305"/></c>
575  <c>307</c> <c>Temporary Redirect</c> <c><xref target="status.307"/></c>
576
577  <c>400</c> <c>Bad Request</c> <c><xref target="status.400"/></c>
578  <c>401</c> <c>Unauthorized</c> <c>&status-401;</c>
579  <c>402</c> <c>Payment Required</c> <c><xref target="status.402"/></c>
580  <c>403</c> <c>Forbidden</c> <c><xref target="status.403"/></c>
581  <c>404</c> <c>Not Found</c> <c><xref target="status.404"/></c>
582  <c>405</c> <c>Method Not Allowed</c> <c><xref target="status.405"/></c>
583  <c>406</c> <c>Not Acceptable</c> <c><xref target="status.406"/></c>
584  <c>407</c> <c>Proxy Authentication Required</c> <c>&status-407;</c>
585  <c>408</c> <c>Request Time-out</c> <c><xref target="status.408"/></c>
586  <c>409</c> <c>Conflict</c> <c><xref target="status.409"/></c>
587  <c>410</c> <c>Gone</c> <c><xref target="status.410"/></c>
588  <c>411</c> <c>Length Required</c> <c><xref target="status.411"/></c>
589  <c>412</c> <c>Precondition Failed</c> <c>&status-412;</c>
590  <c>413</c> <c>Request Representation Too Large</c> <c><xref target="status.413"/></c>
591  <c>414</c> <c>URI Too Long</c> <c><xref target="status.414"/></c>
592  <c>415</c> <c>Unsupported Media Type</c> <c><xref target="status.415"/></c>
593  <c>416</c> <c>Requested range not satisfiable</c> <c>&status-416;</c>
594  <c>417</c> <c>Expectation Failed</c> <c><xref target="status.417"/></c>
595  <c>426</c> <c>Upgrade Required</c> <c><xref target="status.426"/></c>
596
597  <c>500</c> <c>Internal Server Error</c> <c><xref target="status.500"/></c>
598  <c>501</c> <c>Not Implemented</c> <c><xref target="status.501"/></c>
599  <c>502</c> <c>Bad Gateway</c> <c><xref target="status.502"/></c>
600  <c>503</c> <c>Service Unavailable</c> <c><xref target="status.503"/></c>
601  <c>504</c> <c>Gateway Time-out</c> <c><xref target="status.504"/></c>
602  <c>505</c> <c>HTTP Version not supported</c> <c><xref target="status.505"/></c>
603</texttable>
604<t>
605   Note that this list is not exhaustive &mdash; it does not include
606   extension status codes defined in other specifications.
607</t>
608</section>
609
610<section title="Status Code Registry" anchor="status.code.registry">
611<t>
612  The HTTP Status Code Registry defines the name space for the Status-Code
613  token in the Status-Line of an HTTP response.
614</t>
615<t>
616  Values to be added to this name space are subject to IETF review
617  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
618</t>
619<t>
620  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-status-codes"/>.
621</t>
622
623<section title="Considerations for New Status Codes" anchor="considerations.for.new.status.codes">
624<t>
625   When it is necessary to express new semantics for a HTTP response that
626   aren't specific to a single application or media type, and currently defined
627   status codes are inadequate, a new status code can be registered.
628</t>
629<t>
630   HTTP status codes are generic; that is, they are potentially applicable to
631   any resource, not just one particular media type, "type" of resource, or
632   application. As such, it is preferred that new HTTP status codes be
633   registered in a document that isn't specific to a single application, so
634   that this is clear.
635</t>
636<t>
637   Definitions of new HTTP status codes typically explain the request
638   conditions that produce a response containing the status code (e.g.,
639   combinations of request headers and/or method(s)), along with any
640   interactions with response headers (e.g., those that are required, those
641   that modify the semantics of the response).
642</t>
643<t>
644   New HTTP status codes are required to fall under one of the categories
645   defined in <xref target="status.codes"/>. To allow existing parsers to
646   properly handle them, new status codes cannot disallow a response body,
647   although they can mandate a zero-length response body. They can require the
648   presence of one or more particular HTTP response header(s).
649</t>
650<t>
651   Likewise, their definitions can specify that caches are allowed to use
652   heuristics to determine their freshness (see &caching;; by default, it is
653   not allowed), and can define how to determine the resource which they
654   carry a representation for (see <xref
655   target="identifying.response.associated.with.representation"/>; by default,
656   it is anonymous).
657</t>
658</section>
659
660</section>
661
662</section>
663
664<section title="Response Header Fields" anchor="response.header.fields">
665  <x:anchor-alias value="response-header"/>
666<t>
667   The response header fields allow the server to pass additional
668   information about the response which cannot be placed in the Status-Line.
669   These header fields give information about the server and about
670   further access to the target resource (&effective-request-uri;).
671</t>
672<texttable align="left">
673  <ttcol>Header Field Name</ttcol><ttcol>Defined in...</ttcol>
674
675  <c>Accept-Ranges</c> <c>&header-accept-ranges;</c>
676  <c>Age</c> <c>&header-age;</c>
677  <c>Allow</c> <c><xref target="header.allow"/></c>
678  <c>ETag</c> <c>&header-etag;</c>
679  <c>Location</c> <c><xref target="header.location"/></c>
680  <c>Proxy-Authenticate</c> <c>&header-proxy-authenticate;</c>
681  <c>Retry-After</c> <c><xref target="header.retry-after"/></c>
682  <c>Server</c> <c><xref target="header.server"/></c>
683  <c>Vary</c> <c>&header-vary;</c>
684  <c>WWW-Authenticate</c> <c>&header-www-authenticate;</c>
685</texttable>
686</section>
687
688<section title="Representation" anchor="representation">
689<t>
690   Request and Response messages &MAY; transfer a representation if not otherwise
691   restricted by the request method or response status code. A representation
692   consists of metadata (representation header fields) and data (representation
693   body).  When a complete or partial representation is enclosed in an HTTP message,
694   it is referred to as the payload of the message. HTTP representations
695   are defined in &payload;.
696</t>
697<t>
698   A representation body is only present in a message when a message-body is
699   present, as described in &message-body;. The representation body is obtained
700   from the message-body by decoding any Transfer-Encoding that might
701   have been applied to ensure safe and proper transfer of the message.
702</t>
703
704<section title="Identifying the Resource Associated with a Representation" anchor="identifying.response.associated.with.representation">
705<t>
706   It is sometimes necessary to determine an identifier for the resource
707   associated with a representation.
708</t>
709<t>
710   An HTTP request representation, when present, is always associated with an
711   anonymous (i.e., unidentified) resource.
712</t>
713<t>
714   In the common case, an HTTP response is a representation of the target
715   resource (see &effective-request-uri;). However, this is not always the
716   case. To determine the URI of the resource a response is associated with,
717   the following rules are used (with the first applicable one being selected):
718</t>
719<t><list style="numbers">
720   <t>If the response status code is 200 or 203 and the request method was GET,
721   the response payload is a representation of the target resource.</t>
722   <t>If the response status code is 204, 206, or 304 and the request method was GET
723   or HEAD, the response payload is a partial representation of the target
724   resource (see &combining-responses;).</t>
725   <t>If the response has a Content-Location header field, and that URI is the same
726   as the effective request URI, the response payload is a representation of the
727   target resource.</t>
728   <t>If the response has a Content-Location header field, and that URI is not the
729   same as the effective request URI, then the response asserts that its
730   payload is a representation of the resource identified by the
731   Content-Location URI. However, such an assertion cannot be trusted unless
732   it can be verified by other means (not defined by HTTP).</t>
733   <t>Otherwise, the response is a representation of an anonymous (i.e.,
734   unidentified) resource.</t>
735</list></t>
736<t>
737  <cref anchor="TODO-req-uri">
738   The comparison function is going to have to be defined somewhere,
739   because we already need to compare URIs for things like cache invalidation.</cref>
740</t>
741</section>
742
743</section>
744
745
746<section title="Method Definitions" anchor="method.definitions">
747<t>
748   The set of common request methods for HTTP/1.1 is defined below. Although
749   this set can be expanded, additional methods cannot be assumed to
750   share the same semantics for separately extended clients and servers.
751</t>
752
753<section title="Safe and Idempotent Methods" anchor="safe.and.idempotent">
754
755<section title="Safe Methods" anchor="safe.methods">
756<iref item="Safe Methods" primary="true"/>
757<t>
758   Implementors need to be aware that the software represents the user in
759   their interactions over the Internet, and need to allow
760   the user to be aware of any actions they take which might have an
761   unexpected significance to themselves or others.
762</t>
763<t>
764   In particular, the convention has been established that the GET, HEAD,
765   OPTIONS, and TRACE request methods &SHOULD-NOT; have the significance
766   of taking an action other than retrieval. These request methods ought
767   to be considered "<x:dfn anchor="safe">safe</x:dfn>".
768   This allows user agents to represent other methods, such as POST, PUT
769   and DELETE, in a special way, so that the user is made aware of the
770   fact that a possibly unsafe action is being requested.
771</t>
772<t>
773   Naturally, it is not possible to ensure that the server does not
774   generate side-effects as a result of performing a GET request; in
775   fact, some dynamic resources consider that a feature. The important
776   distinction here is that the user did not request the side-effects,
777   so therefore cannot be held accountable for them.
778</t>
779</section>
780
781<section title="Idempotent Methods" anchor="idempotent.methods">
782<iref item="Idempotent Methods" primary="true"/>
783<t>
784   Request methods can also have the property of "idempotence" in that,
785   aside from error or expiration issues, the intended effect of multiple
786   identical requests is the same as for a single request.
787   PUT, DELETE, and all safe request methods are idempotent.
788   It is important to note that idempotence refers only to changes
789   requested by the client: a server is free to change its state due
790   to multiple requests for the purpose of tracking those requests,
791   versioning of results, etc.
792</t>
793</section>
794</section>
795
796<section title="OPTIONS" anchor="OPTIONS">
797  <rdf:Description>
798    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
799  </rdf:Description>
800  <iref primary="true" item="OPTIONS method" x:for-anchor=""/>
801  <iref primary="true" item="Methods" subitem="OPTIONS" x:for-anchor=""/>
802<t>
803   The OPTIONS method requests information about the
804   communication options available on the request/response chain
805   identified by the effective request URI. This method allows a client to
806   determine the options and/or requirements associated with a resource,
807   or the capabilities of a server, without implying a resource action
808   or initiating a resource retrieval.
809</t>
810<t>
811   Responses to the OPTIONS method are not cacheable.
812</t>
813<t>
814   If the OPTIONS request includes a message-body (as indicated by the
815   presence of Content-Length or Transfer-Encoding), then the media type
816   &MUST; be indicated by a Content-Type field. Although this
817   specification does not define any use for such a body, future
818   extensions to HTTP might use the OPTIONS body to make more detailed
819   queries on the server.
820</t>
821<t>
822   If the request-target is an asterisk ("*"), the OPTIONS request is
823   intended to apply to the server in general rather than to a specific
824   resource. Since a server's communication options typically depend on
825   the resource, the "*" request is only useful as a "ping" or "no-op"
826   type of method; it does nothing beyond allowing the client to test
827   the capabilities of the server. For example, this can be used to test
828   a proxy for HTTP/1.1 compliance (or lack thereof).
829</t>
830<t>
831   If the request-target is not an asterisk, the OPTIONS request applies
832   only to the options that are available when communicating with that
833   resource.
834</t>
835<t>
836   A 200 response &SHOULD; include any header fields that indicate
837   optional features implemented by the server and applicable to that
838   resource (e.g., Allow), possibly including extensions not defined by
839   this specification. The response body, if any, &SHOULD; also include
840   information about the communication options. The format for such a
841   body is not defined by this specification, but might be defined by
842   future extensions to HTTP. Content negotiation &MAY; be used to select
843   the appropriate response format. If no response body is included, the
844   response &MUST; include a Content-Length field with a field-value of
845   "0".
846</t>
847<t>
848   The Max-Forwards header field &MAY; be used to target a
849   specific proxy in the request chain (see <xref target="header.max-forwards"/>).
850   If no Max-Forwards field is present in the request, then the forwarded
851   request &MUST-NOT; include a Max-Forwards field.
852</t>
853</section>
854
855<section title="GET" anchor="GET">
856  <rdf:Description>
857    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
858  </rdf:Description>
859  <iref primary="true" item="GET method" x:for-anchor=""/>
860  <iref primary="true" item="Methods" subitem="GET" x:for-anchor=""/>
861<t>
862   The GET method requests transfer of a current representation of
863   the target resource.
864</t>
865<t>   
866   If the target resource is a data-producing process, it is the
867   produced data which shall be returned as the representation in the response and not
868   the source text of the process, unless that text happens to be the output of
869   the process.
870</t>
871<t>
872   The semantics of the GET method change to a "conditional GET" if the
873   request message includes an If-Modified-Since, If-Unmodified-Since,
874   If-Match, If-None-Match, or If-Range header field. A conditional GET
875   requests that the representation be transferred only under the
876   circumstances described by the conditional header field(s). The
877   conditional GET request is intended to reduce unnecessary network
878   usage by allowing cached representations to be refreshed without requiring
879   multiple requests or transferring data already held by the client.
880</t>
881<t>
882   The semantics of the GET method change to a "partial GET" if the
883   request message includes a Range header field. A partial GET requests
884   that only part of the representation be transferred, as described in &header-range;.
885   The partial GET request is intended to reduce unnecessary
886   network usage by allowing partially-retrieved representations to be
887   completed without transferring data already held by the client.
888</t>
889<t>
890   Bodies on GET requests have no defined semantics. Note that sending a body
891   on a GET request might cause some existing implementations to reject the
892   request.
893</t>
894<t>
895   The response to a GET request is cacheable and &MAY; be used to satisfy
896   subsequent GET and HEAD requests (see &caching;).
897</t>
898<t>
899   See <xref target="encoding.sensitive.information.in.uris"/> for security considerations when used for forms.
900</t>
901</section>
902
903<section title="HEAD" anchor="HEAD">
904  <rdf:Description>
905    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
906  </rdf:Description>
907  <iref primary="true" item="HEAD method" x:for-anchor=""/>
908  <iref primary="true" item="Methods" subitem="HEAD" x:for-anchor=""/>
909<t>
910   The HEAD method is identical to GET except that the server &MUST-NOT;
911   return a message-body in the response. The metadata contained
912   in the HTTP header fields in response to a HEAD request &SHOULD; be identical
913   to the information sent in response to a GET request. This method can
914   be used for obtaining metadata about the representation implied by the
915   request without transferring the representation body. This method is
916   often used for testing hypertext links for validity, accessibility,
917   and recent modification.
918</t>
919<t>
920   The response to a HEAD request is cacheable and &MAY; be used to satisfy
921   a subsequent HEAD request; see &caching;. It also &MAY; be used to update a previously cached
922   representation from that resource; if the new field values
923   indicate that the cached representation differs from the current representation (as
924   would be indicated by a change in Content-Length, Content-MD5, ETag
925   or Last-Modified), then the cache &MUST; treat the cache entry as
926   stale.
927</t>
928<t>
929   Bodies on HEAD requests have no defined semantics. Note that sending a body
930   on a HEAD request might cause some existing implementations to reject the
931   request.
932</t>
933</section>
934
935<section title="POST" anchor="POST">
936  <iref primary="true" item="POST method" x:for-anchor=""/>
937  <iref primary="true" item="Methods" subitem="POST" x:for-anchor=""/>
938<t>
939   The POST method requests that the origin server accept the
940   representation enclosed in the request as data to be processed by the
941   target resource. POST is designed to allow a uniform method to cover the
942   following functions:
943  <list style="symbols">
944    <t>
945      Annotation of existing resources;
946    </t>
947    <t>
948        Posting a message to a bulletin board, newsgroup, mailing list,
949        or similar group of articles;
950    </t>
951    <t>
952        Providing a block of data, such as the result of submitting a
953        form, to a data-handling process;
954    </t>
955    <t>
956        Extending a database through an append operation.
957    </t>
958  </list>
959</t>
960<t>
961   The actual function performed by the POST method is determined by the
962   server and is usually dependent on the effective request URI.
963</t>
964<t>
965   The action performed by the POST method might not result in a
966   resource that can be identified by a URI. In this case, either 200
967   (OK) or 204 (No Content) is the appropriate response status code,
968   depending on whether or not the response includes a representation that
969   describes the result.
970</t>
971<t>
972   If a resource has been created on the origin server, the response
973   &SHOULD; be 201 (Created) and contain a representation which describes the
974   status of the request and refers to the new resource, and a Location
975   header field (see <xref target="header.location"/>).
976</t>
977<t>
978   Responses to POST requests are only cacheable when they
979   include explicit freshness information (see &p6-explicit;). A
980   cached POST response with a Content-Location header field
981   (see &header-content-location;) whose value is the effective
982   Request URI &MAY; be used to satisfy subsequent GET and HEAD requests.
983</t>
984<t>
985   Note that POST caching is not widely implemented.
986   However, the 303 (See Other) response can be used to direct the
987   user agent to retrieve a cacheable resource.
988</t>
989</section>
990
991<section title="PUT" anchor="PUT">
992  <iref primary="true" item="PUT method" x:for-anchor=""/>
993  <iref primary="true" item="Methods" subitem="PUT" x:for-anchor=""/>
994<t>
995   The PUT method requests that the state of the target resource
996   be created or replaced with the state defined by the representation
997   enclosed in the request message payload.  A successful PUT of a given
998   representation would suggest that a subsequent GET on that same target
999   resource will result in an equivalent representation being returned in
1000   a 200 (OK) response.  However, there is no guarantee that such a state
1001   change will be observable, since the target resource might be acted
1002   upon by other user agents in parallel, or might be subject to dynamic
1003   processing by the origin server, before any subsequent GET is received.
1004   A successful response only implies that the user agent's intent was
1005   achieved at the time of its processing by the origin server.
1006</t>
1007<t>   
1008   If the target resource does not have a current representation and
1009   the PUT successfully creates one, then the origin server &MUST; inform
1010   the user agent by sending a 201 (Created) response.  If the target
1011   resource does have a current representation and that representation is
1012   successfully modified in accordance with the state of the enclosed
1013   representation, then either a 200 (OK) or 204 (No Content) response
1014   &SHOULD; be sent to indicate successful completion of the request.
1015</t>
1016<t>
1017   Unrecognized header fields &SHOULD; be ignored (i.e., not saved
1018   as part of the resource state).
1019</t>
1020<t>
1021   An origin server &SHOULD; verify that the PUT representation is
1022   consistent with any constraints which the server has for the target
1023   resource that cannot or will not be changed by the PUT.  This is
1024   particularly important when the origin server uses internal
1025   configuration information related to the URI in order to set the
1026   values for representation metadata on GET responses.  When a PUT
1027   representation is inconsistent with the target resource, the origin
1028   server &SHOULD; either make them consistent, by transforming the
1029   representation or changing the resource configuration, or respond
1030   with an appropriate error message containing sufficient information
1031   to explain why the representation is unsuitable.  The 409 (Conflict)
1032   or 415 (Unsupported Media Type) status codes are suggested, with the
1033   latter being specific to constraints on Content-Type values.
1034</t>
1035<t>
1036   For example, if the target resource is configured to always have a
1037   Content-Type of "text/html" and the representation being PUT has a
1038   Content-Type of "image/jpeg", then the origin server &SHOULD; do one of:
1039   (a) reconfigure the target resource to reflect the new media type;
1040   (b) transform the PUT representation to a format consistent with that
1041   of the resource before saving it as the new resource state; or,
1042   (c) reject the request with a 415 response indicating that the target
1043   resource is limited to "text/html", perhaps including a link to a
1044   different resource that would be a suitable target for the new
1045   representation.
1046</t>
1047<t>
1048   HTTP does not define exactly how a PUT method affects the state
1049   of an origin server beyond what can be expressed by the intent of
1050   the user agent request and the semantics of the origin server response.
1051   It does not define what a resource might be, in any sense of that
1052   word, beyond the interface provided via HTTP.  It does not define
1053   how resource state is "stored", nor how such storage might change
1054   as a result of a change in resource state, nor how the origin server
1055   translates resource state into representations.  Generally speaking,
1056   all implementation details behind the resource interface are
1057   intentionally hidden by the server.
1058</t>
1059<t>
1060   The fundamental difference between the POST and PUT methods is
1061   highlighted by the different intent for the target resource.
1062   The target resource in a POST request is intended to handle the
1063   enclosed representation as a data-accepting process, such as for
1064   a gateway to some other protocol or a document that accepts annotations.
1065   In contrast, the target resource in a PUT request is intended to
1066   take the enclosed representation as a new or replacement value.
1067   Hence, the intent of PUT is idempotent and visible to intermediaries,
1068   even though the exact effect is only known by the origin server.
1069</t>
1070<t>
1071   Proper interpretation of a PUT request presumes that the user agent
1072   knows what target resource is desired.  A service that is intended
1073   to select a proper URI on behalf of the client, after receiving
1074   a state-changing request, &SHOULD; be implemented using the POST
1075   method rather than PUT.  If the origin server will not make the
1076   requested PUT state change to the target resource and instead
1077   wishes to have it applied to a different resource, such as when the
1078   resource has been moved to a different URI, then the origin server
1079   &MUST; send a 301 (Moved Permanently) response; the user agent &MAY;
1080   then make its own decision regarding whether or not to redirect the
1081   request.
1082</t>
1083<t>
1084   A PUT request applied to the target resource &MAY; have side-effects
1085   on other resources.  For example, an article might have a URI for
1086   identifying "the current version" (a resource) which is separate
1087   from the URIs identifying each particular version (different
1088   resources that at one point shared the same state as the current version
1089   resource).  A successful PUT request on "the current version" URI might
1090   therefore create a new version resource in addition to changing the
1091   state of the target resource, and might also cause links to be added
1092   between the related resources.
1093</t>
1094<t>
1095   An origin server &SHOULD; reject any PUT request that contains a
1096   Content-Range header field, since it might be misinterpreted as
1097   partial content (or might be partial content that is being mistakenly
1098   PUT as a full representation).  Partial content updates are
1099   possible by targeting a separately identified resource with state
1100   that overlaps a portion of the larger resource, or by using a
1101   different method that has been specifically defined for partial
1102   updates (for example, the PATCH method defined in
1103   <xref target="RFC5789"/>).
1104</t>
1105<t>
1106   Responses to the PUT method are not cacheable. If a PUT request passes
1107   through a cache that has one or more stored responses for the effective
1108   request URI, those stored responses will be invalidated (see
1109   &p6-invalid;).
1110</t>
1111</section>
1112
1113<section title="DELETE" anchor="DELETE">
1114  <iref primary="true" item="DELETE method" x:for-anchor=""/>
1115  <iref primary="true" item="Methods" subitem="DELETE" x:for-anchor=""/>
1116<t>
1117   The DELETE method requests that the origin server delete the target
1118   resource. This method &MAY; be overridden by
1119   human intervention (or other means) on the origin server. The client cannot
1120   be guaranteed that the operation has been carried out, even if the
1121   status code returned from the origin server indicates that the action
1122   has been completed successfully. However, the server &SHOULD-NOT; 
1123   indicate success unless, at the time the response is given, it
1124   intends to delete the resource or move it to an inaccessible
1125   location.
1126</t>
1127<t>
1128   A successful response &SHOULD; be 200 (OK) if the response includes an
1129   representation describing the status, 202 (Accepted) if the action has not
1130   yet been enacted, or 204 (No Content) if the action has been enacted
1131   but the response does not include a representation.
1132</t>
1133<t>
1134   Bodies on DELETE requests have no defined semantics. Note that sending a body
1135   on a DELETE request might cause some existing implementations to reject the
1136   request.
1137</t>
1138<t>
1139   Responses to the DELETE method are not cacheable. If a DELETE request
1140   passes through a cache that has one or more stored responses for the
1141   effective request URI, those stored responses will be invalidated (see
1142   &p6-invalid;).
1143</t>
1144</section>
1145
1146<section title="TRACE" anchor="TRACE">
1147  <rdf:Description>
1148    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
1149  </rdf:Description>
1150  <iref primary="true" item="TRACE method" x:for-anchor=""/>
1151  <iref primary="true" item="Methods" subitem="TRACE" x:for-anchor=""/>
1152<t>
1153   The TRACE method requests a remote, application-layer loop-back
1154   of the request message. The final recipient of the request
1155   &SHOULD; reflect the message received back to the client as the
1156   message-body of a 200 (OK) response. The final recipient is either the
1157   origin server or the first proxy to receive a Max-Forwards
1158   value of zero (0) in the request (see <xref target="header.max-forwards"/>).
1159   A TRACE request &MUST-NOT; include a message-body.
1160</t>
1161<t>
1162   TRACE allows the client to see what is being received at the other
1163   end of the request chain and use that data for testing or diagnostic
1164   information. The value of the Via header field (&header-via;) is of
1165   particular interest, since it acts as a trace of the request chain.
1166   Use of the Max-Forwards header field allows the client to limit the
1167   length of the request chain, which is useful for testing a chain of
1168   proxies forwarding messages in an infinite loop.
1169</t>
1170<t>
1171   If the request is valid, the response &SHOULD; have a Content-Type of
1172   "message/http" (see &media-type-message-http;) and contain a message-body
1173   that encloses a copy of the entire request message.
1174   Responses to the TRACE method are not cacheable.
1175</t>
1176</section>
1177
1178<section title="CONNECT" anchor="CONNECT">
1179  <iref primary="true" item="CONNECT method" x:for-anchor=""/>
1180  <iref primary="true" item="Methods" subitem="CONNECT" x:for-anchor=""/>
1181<t>
1182   The CONNECT method requests that the proxy establish a tunnel
1183   to the request-target and then restrict its behavior to blind
1184   forwarding of packets until the connection is closed.
1185</t>
1186<t>
1187   When using CONNECT, the request-target &MUST; use the authority form
1188   (&request-target;); i.e., the request-target consists of only the
1189   host name and port number of the tunnel destination, separated by a colon.
1190   For example,
1191</t>
1192<figure><artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
1193CONNECT server.example.com:80 HTTP/1.1
1194Host: server.example.com:80
1195
1196</artwork></figure>
1197<t>
1198   Other HTTP mechanisms can be used normally with the CONNECT method &mdash;
1199   except end-to-end protocol Upgrade requests, since the
1200   tunnel must be established first.
1201</t>
1202<t>
1203   For example, proxy authentication might be used to establish the
1204   authority to create a tunnel:
1205</t>
1206<figure><artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
1207CONNECT server.example.com:80 HTTP/1.1
1208Host: server.example.com:80
1209Proxy-Authorization: basic aGVsbG86d29ybGQ=
1210
1211</artwork></figure>
1212<t>
1213   Bodies on CONNECT requests have no defined semantics. Note that sending a body
1214   on a CONNECT request might cause some existing implementations to reject the
1215   request.
1216</t>
1217<t>
1218   Like any other pipelined HTTP/1.1 request, data to be tunnel may be
1219   sent immediately after the blank line. The usual caveats also apply:
1220   data may be discarded if the eventual response is negative, and the
1221   connection may be reset with no response if more than one TCP segment
1222   is outstanding.
1223</t>
1224
1225<section title="Establishing a Tunnel with CONNECT">
1226<t>
1227   Any successful (2xx) response to a CONNECT request indicates that the
1228   proxy has established a connection to the requested host and port,
1229   and has switched to tunneling the current connection to that server
1230   connection.
1231</t>
1232<t>
1233   It may be the case that the proxy itself can only reach the requested
1234   origin server through another proxy.  In this case, the first proxy
1235   &SHOULD; make a CONNECT request of that next proxy, requesting a tunnel
1236   to the authority.  A proxy &MUST-NOT; respond with any 2xx status code
1237   unless it has either a direct or tunnel connection established to the
1238   authority.
1239</t>
1240<t>
1241   An origin server which receives a CONNECT request for itself &MAY;
1242   respond with a 2xx status code to indicate that a connection is
1243   established.
1244</t>
1245<t>
1246   If at any point either one of the peers gets disconnected, any
1247   outstanding data that came from that peer will be passed to the other
1248   one, and after that also the other connection will be terminated by
1249   the proxy. If there is outstanding data to that peer undelivered,
1250   that data will be discarded.
1251</t>
1252
1253</section>
1254</section>
1255</section>
1256
1257
1258<section title="Status Code Definitions" anchor="status.codes">
1259<t>
1260   Each Status-Code is described below, including any metadata required
1261   in the response.
1262</t>
1263
1264<section title="Informational 1xx" anchor="status.1xx">
1265<t>
1266   This class of status code indicates a provisional response,
1267   consisting only of the Status-Line and optional header fields, and is
1268   terminated by an empty line. There are no required header fields for this
1269   class of status code. Since HTTP/1.0 did not define any 1xx status
1270   codes, servers &MUST-NOT; send a 1xx response to an HTTP/1.0 client
1271   except under experimental conditions.
1272</t>
1273<t>
1274   A client &MUST; be prepared to accept one or more 1xx status responses
1275   prior to a regular response, even if the client does not expect a 100
1276   (Continue) status message. Unexpected 1xx status responses &MAY; be
1277   ignored by a user agent.
1278</t>
1279<t>
1280   Proxies &MUST; forward 1xx responses, unless the connection between the
1281   proxy and its client has been closed, or unless the proxy itself
1282   requested the generation of the 1xx response. (For example, if a
1283   proxy adds a "Expect: 100-continue" field when it forwards a request,
1284   then it need not forward the corresponding 100 (Continue)
1285   response(s).)
1286</t>
1287
1288<section title="100 Continue" anchor="status.100">
1289  <iref primary="true" item="100 Continue (status code)" x:for-anchor=""/>
1290  <iref primary="true" item="Status Codes" subitem="100 Continue" x:for-anchor=""/>
1291<t>
1292   The client &SHOULD; continue with its request. This interim response is
1293   used to inform the client that the initial part of the request has
1294   been received and has not yet been rejected by the server. The client
1295   &SHOULD; continue by sending the remainder of the request or, if the
1296   request has already been completed, ignore this response. The server
1297   &MUST; send a final response after the request has been completed. See
1298   &use100; for detailed discussion of the use and handling of this
1299   status code.
1300</t>
1301</section>
1302
1303<section title="101 Switching Protocols" anchor="status.101">
1304  <iref primary="true" item="101 Switching Protocols (status code)" x:for-anchor=""/>
1305  <iref primary="true" item="Status Codes" subitem="101 Switching Protocols" x:for-anchor=""/>
1306<t>
1307   The server understands and is willing to comply with the client's
1308   request, via the Upgrade message header field (&header-upgrade;), for a
1309   change in the application protocol being used on this connection. The
1310   server will switch protocols to those defined by the response's
1311   Upgrade header field immediately after the empty line which
1312   terminates the 101 response.
1313</t>
1314<t>
1315   The protocol &SHOULD; be switched only when it is advantageous to do
1316   so. For example, switching to a newer version of HTTP is advantageous
1317   over older versions, and switching to a real-time, synchronous
1318   protocol might be advantageous when delivering resources that use
1319   such features.
1320</t>
1321</section>
1322</section>
1323
1324<section title="Successful 2xx" anchor="status.2xx">
1325<t>
1326   This class of status code indicates that the client's request was
1327   successfully received, understood, and accepted.
1328</t>
1329
1330<section title="200 OK" anchor="status.200">
1331  <iref primary="true" item="200 OK (status code)" x:for-anchor=""/>
1332  <iref primary="true" item="Status Codes" subitem="200 OK" x:for-anchor=""/>
1333<t>
1334   The request has succeeded. The payload returned with the response
1335   is dependent on the method used in the request, for example:
1336  <list style="hanging">
1337    <t hangText="GET">
1338      a representation of the target resource is sent in the response;
1339    </t>
1340    <t hangText="HEAD">
1341      the same representation as GET, except without the message-body;
1342    </t>
1343    <t hangText="POST">
1344      a representation describing or containing the result of the action;
1345    </t>
1346    <t hangText="TRACE">
1347      a representation containing the request message as received by the
1348      end server.
1349    </t>
1350  </list>
1351</t>
1352<t>
1353   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1354   freshness for 200 responses.
1355</t>
1356</section>
1357
1358<section title="201 Created" anchor="status.201">
1359  <iref primary="true" item="201 Created (status code)" x:for-anchor=""/>
1360  <iref primary="true" item="Status Codes" subitem="201 Created" x:for-anchor=""/>
1361<t>
1362   The request has been fulfilled and has resulted in a new resource being
1363   created. The newly created resource can be referenced by the URI(s)
1364   returned in the payload of the response, with the most specific URI
1365   for the resource given by a Location header field. The response
1366   &SHOULD; include a payload containing a list of resource
1367   characteristics and location(s) from which the user or user agent can
1368   choose the one most appropriate. The payload format is specified by
1369   the media type given in the Content-Type header field. The origin
1370   server &MUST; create the resource before returning the 201 status code.
1371   If the action cannot be carried out immediately, the server &SHOULD;
1372   respond with 202 (Accepted) response instead.
1373</t>
1374<t>
1375   A 201 response &MAY; contain an ETag response header field indicating
1376   the current value of the entity-tag for the representation of the resource
1377   just created (see &header-etag;).
1378</t>
1379</section>
1380
1381<section title="202 Accepted" anchor="status.202">
1382  <iref primary="true" item="202 Accepted (status code)" x:for-anchor=""/>
1383  <iref primary="true" item="Status Codes" subitem="202 Accepted" x:for-anchor=""/>
1384<t>
1385   The request has been accepted for processing, but the processing has
1386   not been completed.  The request might or might not eventually be
1387   acted upon, as it might be disallowed when processing actually takes
1388   place. There is no facility for re-sending a status code from an
1389   asynchronous operation such as this.
1390</t>
1391<t>
1392   The 202 response is intentionally non-committal. Its purpose is to
1393   allow a server to accept a request for some other process (perhaps a
1394   batch-oriented process that is only run once per day) without
1395   requiring that the user agent's connection to the server persist
1396   until the process is completed. The representation returned with this
1397   response &SHOULD; include an indication of the request's current status
1398   and either a pointer to a status monitor or some estimate of when the
1399   user can expect the request to be fulfilled.
1400</t>
1401</section>
1402
1403<section title="203 Non-Authoritative Information" anchor="status.203">
1404  <iref primary="true" item="203 Non-Authoritative Information (status code)" x:for-anchor=""/>
1405  <iref primary="true" item="Status Codes" subitem="203 Non-Authoritative Information" x:for-anchor=""/>
1406<t>
1407   The representation in the response has been transformed or otherwise
1408   modified by a transforming proxy (&intermediaries;).  Note that the
1409   behaviour of transforming intermediaries is controlled by the no-transform
1410   Cache-Control directive (&header-cache-control;).
1411</t>
1412<t>
1413   This status code is only appropriate when the response status code would
1414   have been 200 (OK) otherwise. When the status code before transformation
1415   would have been different, the 214 Transformation Applied warn-code
1416   (&header-warning;) is appropriate.
1417</t>
1418<t>
1419   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1420   freshness for 203 responses.
1421</t>
1422</section>
1423
1424<section title="204 No Content" anchor="status.204">
1425  <iref primary="true" item="204 No Content (status code)" x:for-anchor=""/>
1426  <iref primary="true" item="Status Codes" subitem="204 No Content" x:for-anchor=""/>
1427<t>
1428   The 204 (No Content) status code indicates that the server has
1429   successfully fulfilled the request and that there is no additional
1430   content to return in the response payload body.  Metadata in the
1431   response header fields refer to the target resource and its current
1432   representation after the requested action.
1433</t>
1434<t>
1435   For example, if a 204 status code is received in response to a PUT
1436   request and the response contains an ETag header field, then the PUT
1437   was successful and the ETag field-value contains the entity-tag for
1438   the new representation of that target resource.
1439</t>
1440<t>
1441   The 204 response allows a server to indicate that the action has been
1442   successfully applied to the target resource while implying that the
1443   user agent &SHOULD-NOT; traverse away from its current "document view"
1444   (if any).  The server assumes that the user agent will provide some
1445   indication of the success to its user, in accord with its own interface,
1446   and apply any new or updated metadata in the response to the active
1447   representation.
1448</t>
1449<t>
1450   For example, a 204 status code is commonly used with document editing
1451   interfaces corresponding to a "save" action, such that the document
1452   being saved remains available to the user for editing. It is also
1453   frequently used with interfaces that expect automated data transfers
1454   to be prevalent, such as within distributed version control systems.
1455</t>
1456<t>
1457   The 204 response &MUST-NOT; include a message-body, and thus is always
1458   terminated by the first empty line after the header fields.
1459</t>
1460</section>
1461
1462<section title="205 Reset Content" anchor="status.205">
1463  <iref primary="true" item="205 Reset Content (status code)" x:for-anchor=""/>
1464  <iref primary="true" item="Status Codes" subitem="205 Reset Content" x:for-anchor=""/>
1465<t>
1466   The server has fulfilled the request and the user agent &SHOULD; reset
1467   the document view which caused the request to be sent. This response
1468   is primarily intended to allow input for actions to take place via
1469   user input, followed by a clearing of the form in which the input is
1470   given so that the user can easily initiate another input action.
1471</t>
1472<t>   
1473   The message-body included with the response &MUST; be empty. Note that
1474   receivers still need to parse the response according to the algorithm defined
1475   in &message-body;.
1476</t>
1477</section>
1478
1479<section title="206 Partial Content" anchor="status.206">
1480  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
1481  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
1482  <rdf:Description>
1483    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1484  </rdf:Description>
1485<t>
1486   The server has fulfilled the partial GET request for the resource
1487   and the enclosed payload is a partial representation as defined in &status-206;.
1488</t>
1489<t>
1490   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1491   freshness for 206 responses.
1492</t>
1493</section>
1494</section>
1495
1496<section title="Redirection 3xx" anchor="status.3xx">
1497<t>
1498   This class of status code indicates that further action needs to be
1499   taken by the user agent in order to fulfill the request.  The action
1500   required &MAY; be carried out by the user agent without interaction
1501   with the user if and only if the method used in the second request is
1502   known to be "safe", as defined in <xref target="safe.methods"/>.
1503   A client &SHOULD; detect infinite redirection loops, since such loops
1504   generate network traffic for each redirection.
1505</t>
1506<x:note>
1507  <t>
1508    <x:h>Note:</x:h> An earlier version of this specification recommended a
1509    maximum of five redirections (<xref target="RFC2068" x:fmt="," x:sec="10.3"/>).
1510    Content developers need to be aware that some clients might
1511    implement such a fixed limitation.
1512  </t>
1513</x:note>
1514
1515<section title="300 Multiple Choices" anchor="status.300">
1516  <iref primary="true" item="300 Multiple Choices (status code)" x:for-anchor=""/>
1517  <iref primary="true" item="Status Codes" subitem="300 Multiple Choices" x:for-anchor=""/>
1518<t>
1519   The target resource has more than one
1520   representation, each with its own specific location, and agent-driven
1521   negotiation information (&content-negotiation;) is being provided so that
1522   the user (or user agent) can select a preferred representation by
1523   redirecting its request to that location.
1524</t>
1525<t>
1526   Unless it was a HEAD request, the response &SHOULD; include a representation
1527   containing a list of representation metadata and location(s) from
1528   which the user or user agent can choose the one most appropriate. The
1529   data format is specified by the media type given in the Content-Type
1530   header field. Depending upon the format and the capabilities of
1531   the user agent, selection of the most appropriate choice &MAY; be
1532   performed automatically. However, this specification does not define
1533   any standard for such automatic selection.
1534</t>
1535<t>
1536   If the server has a preferred choice of representation, it &SHOULD;
1537   include the specific URI for that representation in the Location
1538   field; user agents &MAY; use the Location field value for automatic
1539   redirection.
1540</t>
1541<t>
1542   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1543   freshness for 300 responses.
1544</t>
1545
1546</section>
1547
1548<section title="301 Moved Permanently" anchor="status.301">
1549  <iref primary="true" item="301 Moved Permanently (status code)" x:for-anchor=""/>
1550  <iref primary="true" item="Status Codes" subitem="301 Moved Permanently" x:for-anchor=""/>
1551<t>
1552   The target resource has been assigned a new permanent URI and any
1553   future references to this resource &SHOULD; use one of the returned
1554   URIs.  Clients with link editing capabilities ought to automatically
1555   re-link references to the effective request URI to one or more of the new
1556   references returned by the server, where possible.
1557</t>
1558<t>
1559   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1560   freshness for 301 responses.
1561</t>
1562<t>
1563   The new permanent URI &SHOULD; be given by the Location field in the
1564   response. Unless the request method was HEAD, the representation of the
1565   response &SHOULD; contain a short hypertext note with a hyperlink to
1566   the new URI(s).
1567</t>
1568<t>
1569   If the 301 status code is received in response to a request method
1570   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1571   then the request &MAY; be automatically redirected by the user agent without
1572   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1573   request unless it can be confirmed by the user, since this might
1574   change the conditions under which the request was issued.
1575</t>
1576<x:note>
1577  <t>
1578    <x:h>Note:</x:h> When automatically redirecting a POST request after
1579    receiving a 301 status code, some existing HTTP/1.0 user agents
1580    will erroneously change it into a GET request.
1581  </t>
1582</x:note>
1583</section>
1584
1585<section title="302 Found" anchor="status.302">
1586  <iref primary="true" item="302 Found (status code)" x:for-anchor=""/>
1587  <iref primary="true" item="Status Codes" subitem="302 Found" x:for-anchor=""/>
1588<t>
1589   The target resource resides temporarily under a different URI.
1590   Since the redirection might be altered on occasion, the client &SHOULD;
1591   continue to use the effective request URI for future requests.
1592</t>
1593<t>
1594   The temporary URI &SHOULD; be given by the Location field in the
1595   response. Unless the request method was HEAD, the representation of the
1596   response &SHOULD; contain a short hypertext note with a hyperlink to
1597   the new URI(s).
1598</t>
1599<t>
1600   If the 302 status code is received in response to a request method
1601   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1602   then the request &MAY; be automatically redirected by the user agent without
1603   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1604   request unless it can be confirmed by the user, since this might
1605   change the conditions under which the request was issued.
1606</t>
1607<x:note>
1608  <t>
1609    <x:h>Note:</x:h> HTTP/1.0 (<xref target="RFC1945" x:fmt="," x:sec="9.3"/>)
1610    and the first version of HTTP/1.1 (<xref target="RFC2068" x:fmt="," x:sec ="10.3.3"/>)
1611    specify that the client is not allowed to change the method on the
1612    redirected request.  However, most existing user agent implementations
1613    treat 302 as if it were a 303 response, performing a GET on the Location
1614    field-value regardless of the original request method. Therefore, a
1615    previous version of this specification
1616    (<xref target="RFC2616" x:fmt="," x:sec="10.3.3"/>) has added the
1617    status codes
1618    <xref target="status.303" format="none">303</xref> and
1619    <xref target="status.307" format="none">307</xref> for servers that wish
1620    to make unambiguously clear which kind of reaction is expected of the
1621    client.
1622  </t>
1623</x:note>
1624</section>
1625
1626<section title="303 See Other" anchor="status.303">
1627  <iref primary="true" item="303 See Other (status code)" x:for-anchor=""/>
1628  <iref primary="true" item="Status Codes" subitem="303 See Other" x:for-anchor=""/>
1629<t>
1630   The server directs the user agent to a different resource, indicated
1631   by a URI in the Location header field, that provides an indirect
1632   response to the original request.  The user agent &MAY; perform a GET
1633   request on the URI in the Location field in order to obtain a
1634   representation corresponding to the response, be redirected again,
1635   or end with an error status.  The Location URI is not a substitute
1636   reference for the effective request URI.
1637</t>
1638<t>
1639   The 303 status code is generally applicable to any HTTP method.  It is
1640   primarily used to allow the output of a POST action to redirect
1641   the user agent to a selected resource, since doing so provides the
1642   information corresponding to the POST response in a form that
1643   can be separately identified, bookmarked, and cached independent
1644   of the original request.
1645</t>
1646<t>
1647   A 303 response to a GET request indicates that the requested
1648   resource does not have a representation of its own that can be
1649   transferred by the server over HTTP.  The Location URI indicates a
1650   resource that is descriptive of the target resource, such that the
1651   follow-on representation might be useful to recipients without
1652   implying that it adequately represents the target resource.
1653   Note that answers to the questions of what can be represented, what
1654   representations are adequate, and what might be a useful description
1655   are outside the scope of HTTP and thus entirely determined by the
1656   URI owner(s).
1657</t>
1658<t>
1659   Except for responses to a HEAD request, the representation of a 303
1660   response &SHOULD; contain a short hypertext note with a hyperlink
1661   to the Location URI.
1662</t>
1663</section>
1664
1665<section title="304 Not Modified" anchor="status.304">
1666  <iref primary="true" item="304 Not Modified (status code)" x:for-anchor=""/>
1667  <iref primary="true" item="Status Codes" subitem="304 Not Modified" x:for-anchor=""/>
1668  <rdf:Description>
1669    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1670  </rdf:Description>
1671<t>
1672   The response to the request has not been modified since the conditions
1673   indicated by the client's conditional GET request, as defined in &status-304;.
1674</t>
1675</section>
1676
1677<section title="305 Use Proxy" anchor="status.305">
1678  <iref primary="true" item="305 Use Proxy (status code)" x:for-anchor=""/>
1679  <iref primary="true" item="Status Codes" subitem="305 Use Proxy" x:for-anchor=""/>
1680<t>
1681   The 305 status code was defined in a previous version of this specification
1682   (see <xref target="changes.from.rfc.2616"/>), and is now deprecated.
1683</t>
1684</section>
1685
1686<section title="306 (Unused)" anchor="status.306">
1687  <iref primary="true" item="306 (Unused) (status code)" x:for-anchor=""/>
1688  <iref primary="true" item="Status Codes" subitem="306 (Unused)" x:for-anchor=""/>
1689<t>
1690   The 306 status code was used in a previous version of the
1691   specification, is no longer used, and the code is reserved.
1692</t>
1693</section>
1694
1695<section title="307 Temporary Redirect" anchor="status.307">
1696  <iref primary="true" item="307 Temporary Redirect (status code)" x:for-anchor=""/>
1697  <iref primary="true" item="Status Codes" subitem="307 Temporary Redirect" x:for-anchor=""/>
1698<t>
1699   The target resource resides temporarily under a different URI.
1700   Since the redirection can change over time, the client &SHOULD;
1701   continue to use the effective request URI for future requests.
1702</t>
1703<t>
1704   The temporary URI &SHOULD; be given by the Location field in the
1705   response. Unless the request method was HEAD, the representation of the
1706   response &SHOULD; contain a short hypertext note with a hyperlink to
1707   the new URI(s), since many pre-HTTP/1.1 user agents do not
1708   understand the 307 status code. Therefore, the note &SHOULD; contain the
1709   information necessary for a user to repeat the original request on
1710   the new URI.
1711</t>
1712<t>
1713   If the 307 status code is received in response to a request method
1714   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1715   then the request &MAY; be automatically redirected by the user agent without
1716   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1717   request unless it can be confirmed by the user, since this might
1718   change the conditions under which the request was issued.
1719</t>
1720</section>
1721</section>
1722
1723<section title="Client Error 4xx" anchor="status.4xx">
1724<t>
1725   The 4xx class of status code is intended for cases in which the
1726   client seems to have erred. Except when responding to a HEAD request,
1727   the server &SHOULD; include a representation containing an explanation of the
1728   error situation, and whether it is a temporary or permanent
1729   condition. These status codes are applicable to any request method.
1730   User agents &SHOULD; display any included representation to the user.
1731</t>
1732<t>
1733   If the client is sending data, a server implementation using TCP
1734   &SHOULD; be careful to ensure that the client acknowledges receipt of
1735   the packet(s) containing the response, before the server closes the
1736   input connection. If the client continues sending data to the server
1737   after the close, the server's TCP stack will send a reset packet to
1738   the client, which might erase the client's unacknowledged input buffers
1739   before they can be read and interpreted by the HTTP application.
1740</t>
1741
1742<section title="400 Bad Request" anchor="status.400">
1743  <iref primary="true" item="400 Bad Request (status code)" x:for-anchor=""/>
1744  <iref primary="true" item="Status Codes" subitem="400 Bad Request" x:for-anchor=""/>
1745<t>
1746   The request could not be understood by the server due to malformed
1747   syntax. The client &SHOULD-NOT; repeat the request without
1748   modifications.
1749</t>
1750</section>
1751
1752<section title="401 Unauthorized" anchor="status.401">
1753  <iref primary="true" item="401 Unauthorized (status code)" x:for-anchor=""/>
1754  <iref primary="true" item="Status Codes" subitem="401 Unauthorized" x:for-anchor=""/>
1755  <rdf:Description>
1756    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part7</redirects-to>
1757  </rdf:Description>
1758<t>
1759   The request requires user authentication (see &status-401;).
1760</t>
1761</section>
1762
1763<section title="402 Payment Required" anchor="status.402">
1764  <iref primary="true" item="402 Payment Required (status code)" x:for-anchor=""/>
1765  <iref primary="true" item="Status Codes" subitem="402 Payment Required" x:for-anchor=""/>
1766<t>
1767   This code is reserved for future use.
1768</t>
1769</section>
1770
1771<section title="403 Forbidden" anchor="status.403">
1772  <iref primary="true" item="403 Forbidden (status code)" x:for-anchor=""/>
1773  <iref primary="true" item="Status Codes" subitem="403 Forbidden" x:for-anchor=""/>
1774<t>
1775   The server understood the request, but refuses to authorize it. Providing
1776   different user authentication credentials might be successful, but any
1777   credentials that were provided in the request are insufficient. The request
1778   &SHOULD-NOT; be repeated with the same credentials.
1779</t>
1780<t>
1781   If the request method was not HEAD and the server wishes to make
1782   public why the request has not been fulfilled, it &SHOULD; describe the
1783   reason for the refusal in the representation.  If the server does not wish to
1784   make this information available to the client, the status code 404
1785   (Not Found) &MAY; be used instead.
1786</t>
1787</section>
1788
1789<section title="404 Not Found" anchor="status.404">
1790  <iref primary="true" item="404 Not Found (status code)" x:for-anchor=""/>
1791  <iref primary="true" item="Status Codes" subitem="404 Not Found" x:for-anchor=""/>
1792<t>
1793   The server has not found anything matching the effective request URI. No
1794   indication is given of whether the condition is temporary or
1795   permanent. The 410 (Gone) status code &SHOULD; be used if the server
1796   knows, through some internally configurable mechanism, that an old
1797   resource is permanently unavailable and has no forwarding address.
1798   This status code is commonly used when the server does not wish to
1799   reveal exactly why the request has been refused, or when no other
1800   response is applicable.
1801</t>
1802</section>
1803
1804<section title="405 Method Not Allowed" anchor="status.405">
1805  <iref primary="true" item="405 Method Not Allowed (status code)" x:for-anchor=""/>
1806  <iref primary="true" item="Status Codes" subitem="405 Method Not Allowed" x:for-anchor=""/>
1807<t>
1808   The method specified in the Request-Line is not allowed for the target
1809   resource. The response &MUST; include an Allow header field containing a
1810   list of valid methods for the requested resource.
1811</t>
1812</section>
1813
1814<section title="406 Not Acceptable" anchor="status.406">
1815  <iref primary="true" item="406 Not Acceptable (status code)" x:for-anchor=""/>
1816  <iref primary="true" item="Status Codes" subitem="406 Not Acceptable" x:for-anchor=""/>
1817<t>
1818   The resource identified by the request is only capable of generating
1819   response representations which have content characteristics not acceptable
1820   according to the Accept and Accept-* header fields sent in the request
1821   (see &p3-header-fields;).
1822</t>
1823<t>
1824   Unless it was a HEAD request, the response &SHOULD; include a representation
1825   containing a list of available representation characteristics and location(s)
1826   from which the user or user agent can choose the one most
1827   appropriate. The data format is specified by the media type given
1828   in the Content-Type header field. Depending upon the format and the
1829   capabilities of the user agent, selection of the most appropriate
1830   choice &MAY; be performed automatically. However, this specification
1831   does not define any standard for such automatic selection.
1832</t>
1833<x:note>
1834  <t>
1835    <x:h>Note:</x:h> HTTP/1.1 servers are allowed to return responses which are
1836    not acceptable according to the accept header fields sent in the
1837    request. In some cases, this might even be preferable to sending a
1838    406 response. User agents are encouraged to inspect the header fields of
1839    an incoming response to determine if it is acceptable.
1840  </t>
1841</x:note>
1842<t>
1843   If the response could be unacceptable, a user agent &SHOULD;
1844   temporarily stop receipt of more data and query the user for a
1845   decision on further actions.
1846</t>
1847</section>
1848
1849<section title="407 Proxy Authentication Required" anchor="status.407">
1850  <iref primary="true" item="407 Proxy Authentication Required (status code)" x:for-anchor=""/>
1851  <iref primary="true" item="Status Codes" subitem="407 Proxy Authentication Required" x:for-anchor=""/>
1852<t>
1853   This code is similar to 401 (Unauthorized), but indicates that the
1854   client must first authenticate itself with the proxy (see &status-407;).
1855</t>
1856</section>
1857
1858<section title="408 Request Timeout" anchor="status.408">
1859  <iref primary="true" item="408 Request Timeout (status code)" x:for-anchor=""/>
1860  <iref primary="true" item="Status Codes" subitem="408 Request Timeout" x:for-anchor=""/>
1861<t>
1862   The client did not produce a request within the time that the server
1863   was prepared to wait. The client &MAY; repeat the request without
1864   modifications at any later time.
1865</t>
1866</section>
1867
1868<section title="409 Conflict" anchor="status.409">
1869  <iref primary="true" item="409 Conflict (status code)" x:for-anchor=""/>
1870  <iref primary="true" item="Status Codes" subitem="409 Conflict" x:for-anchor=""/>
1871<t>
1872   The request could not be completed due to a conflict with the current
1873   state of the resource. This code is only allowed in situations where
1874   it is expected that the user might be able to resolve the conflict
1875   and resubmit the request. The response body &SHOULD; include enough
1876   information for the user to recognize the source of the conflict.
1877   Ideally, the response representation would include enough information for the
1878   user or user agent to fix the problem; however, that might not be
1879   possible and is not required.
1880</t>
1881<t>
1882   Conflicts are most likely to occur in response to a PUT request. For
1883   example, if versioning were being used and the representation being PUT
1884   included changes to a resource which conflict with those made by an
1885   earlier (third-party) request, the server might use the 409 response
1886   to indicate that it can't complete the request. In this case, the
1887   response representation would likely contain a list of the differences
1888   between the two versions in a format defined by the response
1889   Content-Type.
1890</t>
1891</section>
1892
1893<section title="410 Gone" anchor="status.410">
1894  <iref primary="true" item="410 Gone (status code)" x:for-anchor=""/>
1895  <iref primary="true" item="Status Codes" subitem="410 Gone" x:for-anchor=""/>
1896<t>
1897   The target resource is no longer available at the server and no
1898   forwarding address is known. This condition is expected to be
1899   considered permanent. Clients with link editing capabilities &SHOULD;
1900   delete references to the effective request URI after user approval. If the
1901   server does not know, or has no facility to determine, whether or not
1902   the condition is permanent, the status code 404 (Not Found) &SHOULD; be
1903   used instead.
1904</t>
1905<t>
1906   The 410 response is primarily intended to assist the task of web
1907   maintenance by notifying the recipient that the resource is
1908   intentionally unavailable and that the server owners desire that
1909   remote links to that resource be removed. Such an event is common for
1910   limited-time, promotional services and for resources belonging to
1911   individuals no longer working at the server's site. It is not
1912   necessary to mark all permanently unavailable resources as "gone" or
1913   to keep the mark for any length of time &mdash; that is left to the
1914   discretion of the server owner.
1915</t>
1916<t>
1917   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine freshness
1918   for 410 responses.
1919</t>
1920
1921</section>
1922
1923<section title="411 Length Required" anchor="status.411">
1924  <iref primary="true" item="411 Length Required (status code)" x:for-anchor=""/>
1925  <iref primary="true" item="Status Codes" subitem="411 Length Required" x:for-anchor=""/>
1926<t>
1927   The server refuses to accept the request without a defined Content-Length.
1928   The client &MAY; repeat the request if it adds a valid
1929   Content-Length header field containing the length of the message-body
1930   in the request message.
1931</t>
1932</section>
1933
1934<section title="412 Precondition Failed" anchor="status.412">
1935  <iref primary="true" item="412 Precondition Failed (status code)" x:for-anchor=""/>
1936  <iref primary="true" item="Status Codes" subitem="412 Precondition Failed" x:for-anchor=""/>
1937  <rdf:Description>
1938    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1939  </rdf:Description>
1940<t>
1941   The precondition given in one or more of the header fields
1942   evaluated to false when it was tested on the server, as defined in
1943   &status-412;.
1944</t>
1945</section>
1946
1947<section title="413 Request Representation Too Large" anchor="status.413">
1948  <iref primary="true" item="413 Request Representation Too Large (status code)" x:for-anchor=""/>
1949  <iref primary="true" item="Status Codes" subitem="413 Request Representation Too Large" x:for-anchor=""/>
1950<t>
1951   The server is refusing to process a request because the request
1952   representation is larger than the server is willing or able to process. The
1953   server &MAY; close the connection to prevent the client from continuing
1954   the request.
1955</t>
1956<t>
1957   If the condition is temporary, the server &SHOULD; include a Retry-After
1958   header field to indicate that it is temporary and after what
1959   time the client &MAY; try again.
1960</t>
1961</section>
1962
1963<section title="414 URI Too Long" anchor="status.414">
1964  <iref primary="true" item="414 URI Too Long (status code)" x:for-anchor=""/>
1965  <iref primary="true" item="Status Codes" subitem="414 URI Too Long" x:for-anchor=""/>
1966<t>
1967   The server is refusing to service the request because the effective request URI
1968   is longer than the server is willing to interpret. This rare
1969   condition is only likely to occur when a client has improperly
1970   converted a POST request to a GET request with long query
1971   information, when the client has descended into a URI "black hole" of
1972   redirection (e.g., a redirected URI prefix that points to a suffix of
1973   itself), or when the server is under attack by a client attempting to
1974   exploit security holes present in some servers using fixed-length
1975   buffers for reading or manipulating the effective request URI.
1976</t>
1977</section>
1978
1979<section title="415 Unsupported Media Type" anchor="status.415">
1980  <iref primary="true" item="415 Unsupported Media Type (status code)" x:for-anchor=""/>
1981  <iref primary="true" item="Status Codes" subitem="415 Unsupported Media Type" x:for-anchor=""/>
1982<t>
1983   The server is refusing to service the request because the request
1984   payload is in a format not supported by this request method on the
1985   target resource.
1986</t>
1987</section>
1988
1989<section title="416 Requested Range Not Satisfiable" anchor="status.416">
1990  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
1991  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
1992  <rdf:Description>
1993    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1994  </rdf:Description>
1995<t>
1996   The request included a Range header field (&header-range;) and none of
1997   the range-specifier values in this field overlap the current extent
1998   of the selected resource. See &status-416;.
1999</t>
2000</section>
2001
2002<section title="417 Expectation Failed" anchor="status.417">
2003  <iref primary="true" item="417 Expectation Failed (status code)" x:for-anchor=""/>
2004  <iref primary="true" item="Status Codes" subitem="417 Expectation Failed" x:for-anchor=""/>
2005<t>
2006   The expectation given in an Expect header field (see <xref target="header.expect"/>)
2007   could not be met by this server, or, if the server is a proxy,
2008   the server has unambiguous evidence that the request could not be met
2009   by the next-hop server.
2010</t>
2011</section>
2012
2013<section title="426 Upgrade Required" anchor="status.426">
2014  <iref primary="true" item="426 Upgrade Required (status code)" x:for-anchor=""/>
2015  <iref primary="true" item="Status Codes" subitem="426 Upgrade Required" x:for-anchor=""/>
2016<t>
2017   The request can not be completed without a prior protocol upgrade. This
2018   response &MUST; include an Upgrade header field (&header-upgrade;)
2019   specifying the required protocols.
2020</t>
2021<figure>
2022<preamble>Example:</preamble>
2023<artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
2024HTTP/1.1 426 Upgrade Required
2025Upgrade: HTTP/2.0
2026Connection: Upgrade
2027
2028</artwork></figure>
2029<t>
2030   The server &SHOULD; include a message body in the 426 response which
2031   indicates in human readable form the reason for the error and describes any
2032   alternative courses which may be available to the user.
2033</t>
2034</section>
2035</section>
2036
2037<section title="Server Error 5xx" anchor="status.5xx">
2038<t>
2039   Response status codes beginning with the digit "5" indicate cases in
2040   which the server is aware that it has erred or is incapable of
2041   performing the request. Except when responding to a HEAD request, the
2042   server &SHOULD; include a representation containing an explanation of the
2043   error situation, and whether it is a temporary or permanent
2044   condition. User agents &SHOULD; display any included representation to the
2045   user. These response codes are applicable to any request method.
2046</t>
2047
2048<section title="500 Internal Server Error" anchor="status.500">
2049  <iref primary="true" item="500 Internal Server Error (status code)" x:for-anchor=""/>
2050  <iref primary="true" item="Status Codes" subitem="500 Internal Server Error" x:for-anchor=""/>
2051<t>
2052   The server encountered an unexpected condition which prevented it
2053   from fulfilling the request.
2054</t>
2055</section>
2056
2057<section title="501 Not Implemented" anchor="status.501">
2058  <iref primary="true" item="501 Not Implemented (status code)" x:for-anchor=""/>
2059  <iref primary="true" item="Status Codes" subitem="501 Not Implemented" x:for-anchor=""/>
2060<t>
2061   The server does not support the functionality required to fulfill the
2062   request. This is the appropriate response when the server does not
2063   recognize the request method and is not capable of supporting it for
2064   any resource.
2065</t>
2066</section>
2067
2068<section title="502 Bad Gateway" anchor="status.502">
2069  <iref primary="true" item="502 Bad Gateway (status code)" x:for-anchor=""/>
2070  <iref primary="true" item="Status Codes" subitem="502 Bad Gateway" x:for-anchor=""/>
2071<t>
2072   The server, while acting as a gateway or proxy, received an invalid
2073   response from the upstream server it accessed in attempting to
2074   fulfill the request.
2075</t>
2076</section>
2077
2078<section title="503 Service Unavailable" anchor="status.503">
2079  <iref primary="true" item="503 Service Unavailable (status code)" x:for-anchor=""/>
2080  <iref primary="true" item="Status Codes" subitem="503 Service Unavailable" x:for-anchor=""/>
2081<t>
2082   The server is currently unable or unwilling to handle the request due to
2083   reasons such as temporary overloading, maintenance of the server, or rate
2084   limiting of the client.
2085</t>
2086<t>
2087   The implication is that this is a temporary condition which will be
2088   alleviated after some delay. If known, the length of the delay &MAY; be
2089   indicated in a Retry-After header field (<xref target="header.retry-after"/>).
2090   If no Retry-After is given, the client &SHOULD; handle the response as it
2091   would for a 500 response.
2092</t>
2093<x:note>
2094  <t>
2095    <x:h>Note:</x:h> The existence of the 503 status code does not imply that a
2096    server must use it when becoming overloaded. Some servers might wish
2097    to simply refuse the connection.
2098  </t>
2099</x:note>
2100</section>
2101
2102<section title="504 Gateway Timeout" anchor="status.504">
2103  <iref primary="true" item="504 Gateway Timeout (status code)" x:for-anchor=""/>
2104  <iref primary="true" item="Status Codes" subitem="504 Gateway Timeout" x:for-anchor=""/>
2105<t>
2106   The server, while acting as a gateway or proxy, did not receive a
2107   timely response from the upstream server specified by the URI (e.g.,
2108   HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed
2109   to access in attempting to complete the request.
2110</t>
2111<x:note>
2112  <t>
2113    <x:h>Note</x:h> to implementors: some deployed proxies are known to
2114    return 400 or 500 when DNS lookups time out.
2115  </t>
2116</x:note>
2117</section>
2118
2119<section title="505 HTTP Version Not Supported" anchor="status.505">
2120  <iref primary="true" item="505 HTTP Version Not Supported (status code)" x:for-anchor=""/>
2121  <iref primary="true" item="Status Codes" subitem="505 HTTP Version Not Supported" x:for-anchor=""/>
2122<t>
2123   The server does not support, or refuses to support, the protocol
2124   version that was used in the request message. The server is
2125   indicating that it is unable or unwilling to complete the request
2126   using the same major version as the client, as described in &http-version;,
2127   other than with this error message. The response &SHOULD; contain
2128   a representation describing why that version is not supported and what other
2129   protocols are supported by that server.
2130</t>
2131
2132</section>
2133</section>
2134</section>
2135
2136
2137<section title="Header Field Definitions" anchor="header.fields">
2138<t>
2139   This section defines the syntax and semantics of HTTP/1.1 header fields
2140   related to request and response semantics.
2141</t>
2142
2143<section title="Allow" anchor="header.allow">
2144  <iref primary="true" item="Allow header field" x:for-anchor=""/>
2145  <iref primary="true" item="Header Fields" subitem="Allow" x:for-anchor=""/>
2146  <x:anchor-alias value="Allow"/>
2147<t>
2148   The "Allow" header field lists the set of methods advertised as
2149   supported by the target resource. The purpose of this field is strictly to
2150   inform the recipient of valid request methods associated with the resource.
2151</t>
2152<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Allow"/>
2153  <x:ref>Allow</x:ref> = #<x:ref>Method</x:ref>
2154</artwork></figure>
2155<t>
2156   Example of use:
2157</t>
2158<figure><artwork type="example">
2159  Allow: GET, HEAD, PUT
2160</artwork></figure>
2161<t>
2162   The actual set of allowed methods is defined by the origin server at the
2163   time of each request.
2164</t>
2165<t>
2166   A proxy &MUST-NOT; modify the Allow header field &mdash; it does not need to
2167   understand all the methods specified in order to handle them according to
2168   the generic message handling rules.
2169</t>
2170</section>
2171
2172<section title="Expect" anchor="header.expect">
2173  <iref primary="true" item="Expect header field" x:for-anchor=""/>
2174  <iref primary="true" item="Header Fields" subitem="Expect" x:for-anchor=""/>
2175  <x:anchor-alias value="Expect"/>
2176  <x:anchor-alias value="expectation"/>
2177  <x:anchor-alias value="expectation-extension"/>
2178  <x:anchor-alias value="expect-params"/>
2179<t>
2180   The "Expect" header field is used to indicate that particular
2181   server behaviors are required by the client.
2182</t>
2183<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Expect"/><iref primary="true" item="Grammar" subitem="expectation"/><iref primary="true" item="Grammar" subitem="expectation-extension"/><iref primary="true" item="Grammar" subitem="expect-params"/>
2184  <x:ref>Expect</x:ref>       = 1#<x:ref>expectation</x:ref>
2185 
2186  <x:ref>expectation</x:ref>  = "100-continue" / <x:ref>expectation-extension</x:ref>
2187  <x:ref>expectation-extension</x:ref> = <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> )
2188                           *<x:ref>expect-params</x:ref> ]
2189  <x:ref>expect-params</x:ref> = ";" <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> ) ]
2190</artwork></figure>
2191<t>
2192   A server that does not understand or is unable to comply with any of
2193   the expectation values in the Expect field of a request &MUST; respond
2194   with appropriate error status code. The server &MUST; respond with a 417
2195   (Expectation Failed) status code if any of the expectations cannot be met
2196   or, if there are other problems with the request, some other 4xx
2197   status code.
2198</t>
2199<t>
2200   This header field is defined with extensible syntax to allow for
2201   future extensions. If a server receives a request containing an
2202   Expect field that includes an expectation-extension that it does not
2203   support, it &MUST; respond with a 417 (Expectation Failed) status code.
2204</t>
2205<t>
2206   Comparison of expectation values is case-insensitive for unquoted
2207   tokens (including the 100-continue token), and is case-sensitive for
2208   quoted-string expectation-extensions.
2209</t>
2210<t>
2211   The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy &MUST;
2212   return a 417 (Expectation Failed) status code if it receives a request
2213   with an expectation that it cannot meet. However, the Expect
2214   header field itself is end-to-end; it &MUST; be forwarded if the
2215   request is forwarded.
2216</t>
2217<t>
2218   Many older HTTP/1.0 and HTTP/1.1 applications do not understand the
2219   Expect header field.
2220</t>
2221<t>
2222   See &use100; for the use of the 100 (Continue) status code.
2223</t>
2224</section>
2225
2226<section title="From" anchor="header.from">
2227  <iref primary="true" item="From header field" x:for-anchor=""/>
2228  <iref primary="true" item="Header Fields" subitem="From" x:for-anchor=""/>
2229  <x:anchor-alias value="From"/>
2230  <x:anchor-alias value="mailbox"/>
2231<t>
2232   The "From" header field, if given, &SHOULD; contain an Internet
2233   e-mail address for the human user who controls the requesting user
2234   agent. The address &SHOULD; be machine-usable, as defined by "mailbox"
2235   in <xref x:sec="3.4" x:fmt="of" target="RFC5322"/>:
2236</t>
2237<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="From"/>
2238  <x:ref>From</x:ref>    = <x:ref>mailbox</x:ref>
2239 
2240  <x:ref>mailbox</x:ref> = &lt;mailbox, defined in <xref x:sec="3.4" x:fmt="," target="RFC5322"/>&gt;
2241</artwork></figure>
2242<t>
2243   An example is:
2244</t>
2245<figure><artwork type="example">
2246  From: webmaster@example.org
2247</artwork></figure>
2248<t>
2249   This header field &MAY; be used for logging purposes and as a means for
2250   identifying the source of invalid or unwanted requests. It &SHOULD-NOT; 
2251   be used as an insecure form of access protection. The interpretation
2252   of this field is that the request is being performed on behalf of the
2253   person given, who accepts responsibility for the method performed. In
2254   particular, robot agents &SHOULD; include this header field so that the
2255   person responsible for running the robot can be contacted if problems
2256   occur on the receiving end.
2257</t>
2258<t>
2259   The Internet e-mail address in this field &MAY; be separate from the
2260   Internet host which issued the request. For example, when a request
2261   is passed through a proxy the original issuer's address &SHOULD; be
2262   used.
2263</t>
2264<t>
2265   The client &SHOULD-NOT;  send the From header field without the user's
2266   approval, as it might conflict with the user's privacy interests or
2267   their site's security policy. It is strongly recommended that the
2268   user be able to disable, enable, and modify the value of this field
2269   at any time prior to a request.
2270</t>
2271</section>
2272
2273<section title="Location" anchor="header.location">
2274  <iref primary="true" item="Location header field" x:for-anchor=""/>
2275  <iref primary="true" item="Header Fields" subitem="Location" x:for-anchor=""/>
2276  <x:anchor-alias value="Location"/>
2277<t>
2278   The "Location" header field is used to identify a newly created
2279   resource, or to redirect the recipient to a different location for
2280   completion of the request.
2281</t>
2282<t>
2283   For 201 (Created) responses, the Location is the URI of the new resource
2284   which was created by the request. For 3xx responses, the location &SHOULD;
2285   indicate the server's preferred URI for automatic redirection to the
2286   resource.
2287</t>
2288<t>
2289   The field value consists of a single URI-reference. When it has the form
2290   of a relative reference (<xref target="RFC3986" x:fmt="," x:sec="4.2"/>),
2291   the final value is computed by resolving it against the effective request
2292   URI (<xref target="RFC3986" x:fmt="," x:sec="5"/>).
2293</t>
2294<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Location"/>
2295  <x:ref>Location</x:ref> = <x:ref>URI-reference</x:ref>
2296</artwork></figure>
2297<figure>
2298<preamble>Examples are:</preamble><!--DO NOT DARE changing the vertical WSP below, it's necessary this way for xml2rfc-->
2299<artwork type="example">
2300  Location: http://www.example.org/pub/WWW/People.html#tim
2301</artwork></figure><figure><artwork type="example">  Location: /index.html
2302</artwork></figure>
2303<t>
2304   There are circumstances in which a fragment identifier in a Location URI
2305   would not be appropriate. For instance, when it appears in a 201 Created
2306   response, where the Location header field specifies the URI for the entire
2307   created resource.
2308</t>
2309<x:note>
2310  <t>
2311    <x:h>Note:</x:h> This specification does not define precedence rules
2312    for the case where the original URI, as navigated to by the user
2313    agent, and the Location header field value both contain fragment
2314    identifiers. Thus be aware that including fragment identifiers might
2315    inconvenience anyone relying on the semantics of the original URI's
2316    fragment identifier.
2317  </t>
2318</x:note>
2319<x:note>
2320  <t>
2321    <x:h>Note:</x:h> The Content-Location header field (&header-content-location;) differs
2322    from Location in that the Content-Location identifies the most specific
2323    resource corresponding to the enclosed representation.
2324    It is therefore possible for a response to contain header fields for
2325    both Location and Content-Location.
2326  </t>
2327</x:note>
2328</section>
2329
2330<section title="Max-Forwards" anchor="header.max-forwards">
2331  <iref primary="true" item="Max-Forwards header field" x:for-anchor=""/>
2332  <iref primary="true" item="Header Fields" subitem="Max-Forwards" x:for-anchor=""/>
2333  <x:anchor-alias value="Max-Forwards"/>
2334<t>
2335   The "Max-Forwards" header field provides a mechanism with the
2336   TRACE (<xref target="TRACE"/>) and OPTIONS (<xref target="OPTIONS"/>)
2337   methods to limit the number of times that the request is forwarded by
2338   proxies. This can be useful when the client is attempting to
2339   trace a request which appears to be failing or looping in mid-chain.
2340</t>
2341<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Max-Forwards"/>
2342  <x:ref>Max-Forwards</x:ref> = 1*<x:ref>DIGIT</x:ref>
2343</artwork></figure>
2344<t>
2345   The Max-Forwards value is a decimal integer indicating the remaining
2346   number of times this request message can be forwarded.
2347</t>
2348<t>
2349   Each recipient of a TRACE or OPTIONS request
2350   containing a Max-Forwards header field &MUST; check and update its
2351   value prior to forwarding the request. If the received value is zero
2352   (0), the recipient &MUST-NOT; forward the request; instead, it &MUST;
2353   respond as the final recipient. If the received Max-Forwards value is
2354   greater than zero, then the forwarded message &MUST; contain an updated
2355   Max-Forwards field with a value decremented by one (1).
2356</t>
2357<t>
2358   The Max-Forwards header field &MAY; be ignored for all other request
2359   methods.
2360</t>
2361</section>
2362
2363<section title="Referer" anchor="header.referer">
2364  <iref primary="true" item="Referer header field" x:for-anchor=""/>
2365  <iref primary="true" item="Header Fields" subitem="Referer" x:for-anchor=""/>
2366  <x:anchor-alias value="Referer"/>
2367<t>
2368   The "Referer" [sic] header field allows the client to specify the
2369   URI of the resource from which the effective request URI was obtained (the
2370   "referrer", although the header field is misspelled.).
2371</t>
2372<t>
2373   The Referer header field allows servers to generate lists of back-links to
2374   resources for interest, logging, optimized caching, etc. It also allows
2375   obsolete or mistyped links to be traced for maintenance. Some servers use
2376   Referer as a means of controlling where they allow links from (so-called
2377   "deep linking"), but legitimate requests do not always
2378   contain a Referer header field.
2379</t>
2380<t>
2381   If the effective request URI was obtained from a source that does not have its own
2382   URI (e.g., input from the user keyboard), the Referer field &MUST; either be
2383   sent with the value "about:blank", or not be sent at all. Note that this
2384   requirement does not apply to sources with non-HTTP URIs (e.g., FTP).
2385</t>
2386<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Referer"/>
2387  <x:ref>Referer</x:ref> = <x:ref>absolute-URI</x:ref> / <x:ref>partial-URI</x:ref>
2388</artwork></figure>
2389<t>
2390   Example:
2391</t>
2392<figure><artwork type="example">
2393  Referer: http://www.example.org/hypertext/Overview.html
2394</artwork></figure>
2395<t>
2396   If the field value is a relative URI, it &SHOULD; be interpreted
2397   relative to the effective request URI. The URI &MUST-NOT; include a fragment. See
2398   <xref target="encoding.sensitive.information.in.uris"/> for security considerations.
2399</t>
2400</section>
2401
2402<section title="Retry-After" anchor="header.retry-after">
2403  <iref primary="true" item="Retry-After header field" x:for-anchor=""/>
2404  <iref primary="true" item="Header Fields" subitem="Retry-After" x:for-anchor=""/>
2405  <x:anchor-alias value="Retry-After"/>
2406<t>
2407   The header "Retry-After" field can be used with a 503 (Service
2408   Unavailable) response to indicate how long the service is expected to
2409   be unavailable to the requesting client. This field &MAY; also be used
2410   with any 3xx (Redirection) response to indicate the minimum time the
2411   user-agent is asked wait before issuing the redirected request.
2412</t>
2413<t>
2414   The value of this field can be either an HTTP-date or an integer number
2415   of seconds (in decimal) after the time of the response.
2416</t>
2417<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Retry-After"/>
2418  <x:ref>Retry-After</x:ref> = <x:ref>HTTP-date</x:ref> / <x:ref>delta-seconds</x:ref>
2419</artwork></figure>
2420<t anchor="rule.delta-seconds">
2421  <x:anchor-alias value="delta-seconds"/>
2422   Time spans are non-negative decimal integers, representing time in
2423   seconds.
2424</t>
2425<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="delta-seconds"/>
2426  <x:ref>delta-seconds</x:ref>  = 1*<x:ref>DIGIT</x:ref>
2427</artwork></figure>
2428<t>
2429   Two examples of its use are
2430</t>
2431<figure><artwork type="example">
2432  Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
2433  Retry-After: 120
2434</artwork></figure>
2435<t>
2436   In the latter example, the delay is 2 minutes.
2437</t>
2438</section>
2439
2440<section title="Server" anchor="header.server">
2441  <iref primary="true" item="Server header field" x:for-anchor=""/>
2442  <iref primary="true" item="Header Fields" subitem="Server" x:for-anchor=""/>
2443  <x:anchor-alias value="Server"/>
2444<t>
2445   The "Server" header field contains information about the
2446   software used by the origin server to handle the request.
2447</t>
2448<t>
2449   The field can contain multiple product tokens (&product-tokens;) and
2450   comments (&header-fields;) identifying the server and any significant
2451   subproducts. The product tokens are listed in order of their significance
2452   for identifying the application.
2453</t>
2454<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Server"/>
2455  <x:ref>Server</x:ref> = <x:ref>product</x:ref> *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2456</artwork></figure>
2457<t>
2458   Example:
2459</t>
2460<figure><artwork type="example">
2461  Server: CERN/3.0 libwww/2.17
2462</artwork></figure>
2463<t>
2464   If the response is being forwarded through a proxy, the proxy
2465   application &MUST-NOT; modify the Server header field. Instead, it
2466   &MUST; include a Via field (as described in &header-via;).
2467</t>
2468<x:note>
2469  <t>
2470    <x:h>Note:</x:h> Revealing the specific software version of the server might
2471    allow the server machine to become more vulnerable to attacks
2472    against software that is known to contain security holes. Server
2473    implementors are encouraged to make this field a configurable
2474    option.
2475  </t>
2476</x:note>
2477</section>
2478
2479<section title="User-Agent" anchor="header.user-agent">
2480  <iref primary="true" item="User-Agent header field" x:for-anchor=""/>
2481  <iref primary="true" item="Header Fields" subitem="User-Agent" x:for-anchor=""/>
2482  <x:anchor-alias value="User-Agent"/>
2483<t>
2484   The "User-Agent" header field contains information about the user
2485   agent originating the request. User agents &SHOULD; include this field with
2486   requests.
2487</t>
2488<t>
2489   Typically, it is used for statistical purposes, the tracing of protocol
2490   violations, and tailoring responses to avoid particular user agent
2491   limitations.
2492</t>
2493<t>
2494   The field can contain multiple product tokens (&product-tokens;)
2495   and comments (&header-fields;) identifying the agent and its
2496   significant subproducts. By convention, the product tokens are listed in
2497   order of their significance for identifying the application.
2498</t>
2499<t>
2500   Because this field is usually sent on every request a user agent makes,
2501   implementations are encouraged not to include needlessly fine-grained
2502   detail, and to limit (or even prohibit) the addition of subproducts by third
2503   parties. Overly long and detailed User-Agent field values make requests
2504   larger and can also be used to identify ("fingerprint") the user against
2505   their wishes.
2506</t>
2507<t>
2508   Likewise, implementations are encouraged not to use the product tokens of
2509   other implementations in order to declare compatibility with them, as this
2510   circumvents the purpose of the field. Finally, they are encouraged not to
2511   use comments to identify products; doing so makes the field value more
2512   difficult to parse.
2513</t>
2514<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="User-Agent"/>
2515  <x:ref>User-Agent</x:ref> = <x:ref>product</x:ref> *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2516</artwork></figure>
2517<t>
2518   Example:
2519</t>
2520<figure><artwork type="example">
2521  User-Agent: CERN-LineMode/2.15 libwww/2.17b3
2522</artwork></figure>
2523</section>
2524
2525</section>
2526
2527<section title="IANA Considerations" anchor="IANA.considerations">
2528
2529<section title="Method Registry" anchor="method.registration">
2530<t>
2531  The registration procedure for HTTP request methods is defined by
2532  <xref target="method.registry"/> of this document.
2533</t>
2534<t>
2535   The HTTP Method Registry shall be created at <eref target="http://www.iana.org/assignments/http-methods"/>
2536   and be populated with the registrations below:
2537</t>
2538<?BEGININC p2-semantics.iana-methods ?>
2539<!--AUTOGENERATED FROM extract-method-defs.xslt, do not edit manually-->
2540<texttable align="left" suppress-title="true" anchor="iana.method.registration.table">
2541   <ttcol>Method</ttcol>
2542   <ttcol>Safe</ttcol>
2543   <ttcol>Reference</ttcol>
2544   <c>CONNECT</c>
2545   <c>no</c>
2546   <c>
2547      <xref target="CONNECT"/>
2548   </c>
2549   <c>DELETE</c>
2550   <c>no</c>
2551   <c>
2552      <xref target="DELETE"/>
2553   </c>
2554   <c>GET</c>
2555   <c>yes</c>
2556   <c>
2557      <xref target="GET"/>
2558   </c>
2559   <c>HEAD</c>
2560   <c>yes</c>
2561   <c>
2562      <xref target="HEAD"/>
2563   </c>
2564   <c>OPTIONS</c>
2565   <c>yes</c>
2566   <c>
2567      <xref target="OPTIONS"/>
2568   </c>
2569   <c>POST</c>
2570   <c>no</c>
2571   <c>
2572      <xref target="POST"/>
2573   </c>
2574   <c>PUT</c>
2575   <c>no</c>
2576   <c>
2577      <xref target="PUT"/>
2578   </c>
2579   <c>TRACE</c>
2580   <c>yes</c>
2581   <c>
2582      <xref target="TRACE"/>
2583   </c>
2584</texttable>
2585<!--(END)-->
2586<?ENDINC p2-semantics.iana-methods ?>
2587</section>
2588
2589<section title="Status Code Registry" anchor="status.code.registration">
2590<t>
2591   The registration procedure for HTTP Status Codes &mdash; previously defined
2592   in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/> &mdash; is now defined
2593   by <xref target="status.code.registry"/> of this document.
2594</t>
2595<t>
2596   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
2597   shall be updated with the registrations below:
2598</t>
2599<?BEGININC p2-semantics.iana-status-codes ?>
2600<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
2601<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
2602   <ttcol>Value</ttcol>
2603   <ttcol>Description</ttcol>
2604   <ttcol>Reference</ttcol>
2605   <c>100</c>
2606   <c>Continue</c>
2607   <c>
2608      <xref target="status.100"/>
2609   </c>
2610   <c>101</c>
2611   <c>Switching Protocols</c>
2612   <c>
2613      <xref target="status.101"/>
2614   </c>
2615   <c>200</c>
2616   <c>OK</c>
2617   <c>
2618      <xref target="status.200"/>
2619   </c>
2620   <c>201</c>
2621   <c>Created</c>
2622   <c>
2623      <xref target="status.201"/>
2624   </c>
2625   <c>202</c>
2626   <c>Accepted</c>
2627   <c>
2628      <xref target="status.202"/>
2629   </c>
2630   <c>203</c>
2631   <c>Non-Authoritative Information</c>
2632   <c>
2633      <xref target="status.203"/>
2634   </c>
2635   <c>204</c>
2636   <c>No Content</c>
2637   <c>
2638      <xref target="status.204"/>
2639   </c>
2640   <c>205</c>
2641   <c>Reset Content</c>
2642   <c>
2643      <xref target="status.205"/>
2644   </c>
2645   <c>300</c>
2646   <c>Multiple Choices</c>
2647   <c>
2648      <xref target="status.300"/>
2649   </c>
2650   <c>301</c>
2651   <c>Moved Permanently</c>
2652   <c>
2653      <xref target="status.301"/>
2654   </c>
2655   <c>302</c>
2656   <c>Found</c>
2657   <c>
2658      <xref target="status.302"/>
2659   </c>
2660   <c>303</c>
2661   <c>See Other</c>
2662   <c>
2663      <xref target="status.303"/>
2664   </c>
2665   <c>305</c>
2666   <c>Use Proxy</c>
2667   <c>
2668      <xref target="status.305"/>
2669   </c>
2670   <c>306</c>
2671   <c>(Unused)</c>
2672   <c>
2673      <xref target="status.306"/>
2674   </c>
2675   <c>307</c>
2676   <c>Temporary Redirect</c>
2677   <c>
2678      <xref target="status.307"/>
2679   </c>
2680   <c>400</c>
2681   <c>Bad Request</c>
2682   <c>
2683      <xref target="status.400"/>
2684   </c>
2685   <c>402</c>
2686   <c>Payment Required</c>
2687   <c>
2688      <xref target="status.402"/>
2689   </c>
2690   <c>403</c>
2691   <c>Forbidden</c>
2692   <c>
2693      <xref target="status.403"/>
2694   </c>
2695   <c>404</c>
2696   <c>Not Found</c>
2697   <c>
2698      <xref target="status.404"/>
2699   </c>
2700   <c>405</c>
2701   <c>Method Not Allowed</c>
2702   <c>
2703      <xref target="status.405"/>
2704   </c>
2705   <c>406</c>
2706   <c>Not Acceptable</c>
2707   <c>
2708      <xref target="status.406"/>
2709   </c>
2710   <c>407</c>
2711   <c>Proxy Authentication Required</c>
2712   <c>
2713      <xref target="status.407"/>
2714   </c>
2715   <c>408</c>
2716   <c>Request Timeout</c>
2717   <c>
2718      <xref target="status.408"/>
2719   </c>
2720   <c>409</c>
2721   <c>Conflict</c>
2722   <c>
2723      <xref target="status.409"/>
2724   </c>
2725   <c>410</c>
2726   <c>Gone</c>
2727   <c>
2728      <xref target="status.410"/>
2729   </c>
2730   <c>411</c>
2731   <c>Length Required</c>
2732   <c>
2733      <xref target="status.411"/>
2734   </c>
2735   <c>413</c>
2736   <c>Request Representation Too Large</c>
2737   <c>
2738      <xref target="status.413"/>
2739   </c>
2740   <c>414</c>
2741   <c>URI Too Long</c>
2742   <c>
2743      <xref target="status.414"/>
2744   </c>
2745   <c>415</c>
2746   <c>Unsupported Media Type</c>
2747   <c>
2748      <xref target="status.415"/>
2749   </c>
2750   <c>417</c>
2751   <c>Expectation Failed</c>
2752   <c>
2753      <xref target="status.417"/>
2754   </c>
2755   <c>426</c>
2756   <c>Upgrade Required</c>
2757   <c>
2758      <xref target="status.426"/>
2759   </c>
2760   <c>500</c>
2761   <c>Internal Server Error</c>
2762   <c>
2763      <xref target="status.500"/>
2764   </c>
2765   <c>501</c>
2766   <c>Not Implemented</c>
2767   <c>
2768      <xref target="status.501"/>
2769   </c>
2770   <c>502</c>
2771   <c>Bad Gateway</c>
2772   <c>
2773      <xref target="status.502"/>
2774   </c>
2775   <c>503</c>
2776   <c>Service Unavailable</c>
2777   <c>
2778      <xref target="status.503"/>
2779   </c>
2780   <c>504</c>
2781   <c>Gateway Timeout</c>
2782   <c>
2783      <xref target="status.504"/>
2784   </c>
2785   <c>505</c>
2786   <c>HTTP Version Not Supported</c>
2787   <c>
2788      <xref target="status.505"/>
2789   </c>
2790</texttable>
2791<!--(END)-->
2792<?ENDINC p2-semantics.iana-status-codes ?>
2793</section>
2794<section title="Header Field Registration" anchor="header.field.registration">
2795<t>
2796   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> shall be updated
2797   with the permanent registrations below (see <xref target="RFC3864"/>):
2798</t>
2799<?BEGININC p2-semantics.iana-headers ?>
2800<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
2801<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
2802   <ttcol>Header Field Name</ttcol>
2803   <ttcol>Protocol</ttcol>
2804   <ttcol>Status</ttcol>
2805   <ttcol>Reference</ttcol>
2806
2807   <c>Allow</c>
2808   <c>http</c>
2809   <c>standard</c>
2810   <c>
2811      <xref target="header.allow"/>
2812   </c>
2813   <c>Expect</c>
2814   <c>http</c>
2815   <c>standard</c>
2816   <c>
2817      <xref target="header.expect"/>
2818   </c>
2819   <c>From</c>
2820   <c>http</c>
2821   <c>standard</c>
2822   <c>
2823      <xref target="header.from"/>
2824   </c>
2825   <c>Location</c>
2826   <c>http</c>
2827   <c>standard</c>
2828   <c>
2829      <xref target="header.location"/>
2830   </c>
2831   <c>Max-Forwards</c>
2832   <c>http</c>
2833   <c>standard</c>
2834   <c>
2835      <xref target="header.max-forwards"/>
2836   </c>
2837   <c>Referer</c>
2838   <c>http</c>
2839   <c>standard</c>
2840   <c>
2841      <xref target="header.referer"/>
2842   </c>
2843   <c>Retry-After</c>
2844   <c>http</c>
2845   <c>standard</c>
2846   <c>
2847      <xref target="header.retry-after"/>
2848   </c>
2849   <c>Server</c>
2850   <c>http</c>
2851   <c>standard</c>
2852   <c>
2853      <xref target="header.server"/>
2854   </c>
2855   <c>User-Agent</c>
2856   <c>http</c>
2857   <c>standard</c>
2858   <c>
2859      <xref target="header.user-agent"/>
2860   </c>
2861</texttable>
2862<!--(END)-->
2863<?ENDINC p2-semantics.iana-headers ?>
2864<t>
2865   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
2866</t>
2867</section>
2868</section>
2869
2870<section title="Security Considerations" anchor="security.considerations">
2871<t>
2872   This section is meant to inform application developers, information
2873   providers, and users of the security limitations in HTTP/1.1 as
2874   described by this document. The discussion does not include
2875   definitive solutions to the problems revealed, though it does make
2876   some suggestions for reducing security risks.
2877</t>
2878
2879<section title="Transfer of Sensitive Information" anchor="security.sensitive">
2880<t>
2881   Like any generic data transfer protocol, HTTP cannot regulate the
2882   content of the data that is transferred, nor is there any a priori
2883   method of determining the sensitivity of any particular piece of
2884   information within the context of any given request. Therefore,
2885   applications &SHOULD; supply as much control over this information as
2886   possible to the provider of that information. Four header fields are
2887   worth special mention in this context: Server, Via, Referer and From.
2888</t>
2889<t>
2890   Revealing the specific software version of the server might allow the
2891   server machine to become more vulnerable to attacks against software
2892   that is known to contain security holes. Implementors &SHOULD; make the
2893   Server header field a configurable option.
2894</t>
2895<t>
2896   Proxies which serve as a portal through a network firewall &SHOULD;
2897   take special precautions regarding the transfer of header information
2898   that identifies the hosts behind the firewall. In particular, they
2899   &SHOULD; remove, or replace with sanitized versions, any Via fields
2900   generated behind the firewall.
2901</t>
2902<t>
2903   The Referer header field allows reading patterns to be studied and reverse
2904   links drawn. Although it can be very useful, its power can be abused
2905   if user details are not separated from the information contained in
2906   the Referer. Even when the personal information has been removed, the
2907   Referer header field might indicate a private document's URI whose
2908   publication would be inappropriate.
2909</t>
2910<t>
2911   The information sent in the From field might conflict with the user's
2912   privacy interests or their site's security policy, and hence it
2913   &SHOULD-NOT;  be transmitted without the user being able to disable,
2914   enable, and modify the contents of the field. The user &MUST; be able
2915   to set the contents of this field within a user preference or
2916   application defaults configuration.
2917</t>
2918<t>
2919   We suggest, though do not require, that a convenient toggle interface
2920   be provided for the user to enable or disable the sending of From and
2921   Referer information.
2922</t>
2923<t>
2924   The User-Agent (<xref target="header.user-agent"/>) or Server (<xref
2925   target="header.server"/>) header fields can sometimes be used to determine
2926   that a specific client or server have a particular security hole which might
2927   be exploited. Unfortunately, this same information is often used for other
2928   valuable purposes for which HTTP currently has no better mechanism.
2929</t>
2930<t>
2931   Furthermore, the User-Agent header field may contain enough entropy to be
2932   used, possibly in conjunction with other material, to uniquely identify the
2933   user.
2934</t>
2935<t>
2936   Some request methods, like TRACE (<xref target="TRACE"/>), expose information
2937   that was sent in request header fields within the body of their response.
2938   Clients &SHOULD; be careful with sensitive information, like Cookies,
2939   Authorization credentials, and other header fields that might be used to
2940   collect data from the client.
2941</t> 
2942</section>
2943
2944<section title="Encoding Sensitive Information in URIs" anchor="encoding.sensitive.information.in.uris">
2945<t>
2946   Because the source of a link might be private information or might
2947   reveal an otherwise private information source, it is strongly
2948   recommended that the user be able to select whether or not the
2949   Referer field is sent. For example, a browser client could have a
2950   toggle switch for browsing openly/anonymously, which would
2951   respectively enable/disable the sending of Referer and From
2952   information.
2953</t>
2954<t>
2955   Clients &SHOULD-NOT; include a Referer header field in a (non-secure)
2956   HTTP request if the referring page was transferred with a secure
2957   protocol.
2958</t>
2959<t>
2960   Authors of services &SHOULD-NOT; use GET-based forms for the submission of
2961   sensitive data because that data will be placed in the request-target. Many
2962   existing servers, proxies, and user agents log or display the request-target
2963   in places where it might be visible to third parties. Such services can
2964   use POST-based form submission instead.
2965</t>
2966</section>
2967
2968<section title="Location Headers and Spoofing" anchor="location.spoofing">
2969<t>
2970   If a single server supports multiple organizations that do not trust
2971   one another, then it &MUST; check the values of Location and Content-Location
2972   header fields in responses that are generated under control of
2973   said organizations to make sure that they do not attempt to
2974   invalidate resources over which they have no authority.
2975</t>
2976</section>
2977
2978<section title="Security Considerations for CONNECT">
2979<t>
2980   Since tunneled data is opaque to the proxy, there are additional
2981   risks to tunneling to other well-known or reserved ports.
2982   A HTTP client CONNECTing to port 25 could relay spam
2983   via SMTP, for example. As such, proxies &SHOULD; restrict CONNECT
2984   access to a small number of known ports.
2985</t>
2986</section>
2987
2988</section>
2989
2990<section title="Acknowledgments" anchor="ack">
2991</section>
2992</middle>
2993<back>
2994
2995<references title="Normative References">
2996
2997<reference anchor="Part1">
2998  <front>
2999    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
3000    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3001      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3002      <address><email>fielding@gbiv.com</email></address>
3003    </author>
3004    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3005      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3006      <address><email>jg@freedesktop.org</email></address>
3007    </author>
3008    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3009      <organization abbrev="HP">Hewlett-Packard Company</organization>
3010      <address><email>JeffMogul@acm.org</email></address>
3011    </author>
3012    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3013      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3014      <address><email>henrikn@microsoft.com</email></address>
3015    </author>
3016    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3017      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3018      <address><email>LMM@acm.org</email></address>
3019    </author>
3020    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3021      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3022      <address><email>paulle@microsoft.com</email></address>
3023    </author>
3024    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3025      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3026      <address><email>timbl@w3.org</email></address>
3027    </author>
3028    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3029      <organization abbrev="W3C">World Wide Web Consortium</organization>
3030      <address><email>ylafon@w3.org</email></address>
3031    </author>
3032    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3033      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3034      <address><email>julian.reschke@greenbytes.de</email></address>
3035    </author>
3036    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3037  </front>
3038  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
3039  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
3040</reference>
3041
3042<reference anchor="Part3">
3043  <front>
3044    <title abbrev="HTTP/1.1">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
3045    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3046      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3047      <address><email>fielding@gbiv.com</email></address>
3048    </author>
3049    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3050      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3051      <address><email>jg@freedesktop.org</email></address>
3052    </author>
3053    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3054      <organization abbrev="HP">Hewlett-Packard Company</organization>
3055      <address><email>JeffMogul@acm.org</email></address>
3056    </author>
3057    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3058      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3059      <address><email>henrikn@microsoft.com</email></address>
3060    </author>
3061    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3062      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3063      <address><email>LMM@acm.org</email></address>
3064    </author>
3065    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3066      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3067      <address><email>paulle@microsoft.com</email></address>
3068    </author>
3069    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3070      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3071      <address><email>timbl@w3.org</email></address>
3072    </author>
3073    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3074      <organization abbrev="W3C">World Wide Web Consortium</organization>
3075      <address><email>ylafon@w3.org</email></address>
3076    </author>
3077    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3078      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3079      <address><email>julian.reschke@greenbytes.de</email></address>
3080    </author>
3081    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3082  </front>
3083  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p3-payload-&ID-VERSION;"/>
3084  <x:source href="p3-payload.xml" basename="p3-payload"/>
3085</reference>
3086
3087<reference anchor="Part4">
3088  <front>
3089    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
3090    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3091      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3092      <address><email>fielding@gbiv.com</email></address>
3093    </author>
3094    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3095      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3096      <address><email>jg@freedesktop.org</email></address>
3097    </author>
3098    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3099      <organization abbrev="HP">Hewlett-Packard Company</organization>
3100      <address><email>JeffMogul@acm.org</email></address>
3101    </author>
3102    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3103      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3104      <address><email>henrikn@microsoft.com</email></address>
3105    </author>
3106    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3107      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3108      <address><email>LMM@acm.org</email></address>
3109    </author>
3110    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3111      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3112      <address><email>paulle@microsoft.com</email></address>
3113    </author>
3114    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3115      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3116      <address><email>timbl@w3.org</email></address>
3117    </author>
3118    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3119      <organization abbrev="W3C">World Wide Web Consortium</organization>
3120      <address><email>ylafon@w3.org</email></address>
3121    </author>
3122    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3123      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3124      <address><email>julian.reschke@greenbytes.de</email></address>
3125    </author>
3126    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3127  </front>
3128  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
3129  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
3130</reference>
3131
3132<reference anchor="Part5">
3133  <front>
3134    <title abbrev="HTTP/1.1">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
3135    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3136      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3137      <address><email>fielding@gbiv.com</email></address>
3138    </author>
3139    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3140      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3141      <address><email>jg@freedesktop.org</email></address>
3142    </author>
3143    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3144      <organization abbrev="HP">Hewlett-Packard Company</organization>
3145      <address><email>JeffMogul@acm.org</email></address>
3146    </author>
3147    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3148      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3149      <address><email>henrikn@microsoft.com</email></address>
3150    </author>
3151    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3152      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3153      <address><email>LMM@acm.org</email></address>
3154    </author>
3155    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3156      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3157      <address><email>paulle@microsoft.com</email></address>
3158    </author>
3159    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3160      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3161      <address><email>timbl@w3.org</email></address>
3162    </author>
3163    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3164      <organization abbrev="W3C">World Wide Web Consortium</organization>
3165      <address><email>ylafon@w3.org</email></address>
3166    </author>
3167    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3168      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3169      <address><email>julian.reschke@greenbytes.de</email></address>
3170    </author>
3171    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3172  </front>
3173  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p5-range-&ID-VERSION;"/>
3174  <x:source href="p5-range.xml" basename="p5-range"/>
3175</reference>
3176
3177<reference anchor="Part6">
3178  <front>
3179    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
3180    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3181      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3182      <address><email>fielding@gbiv.com</email></address>
3183    </author>
3184    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3185      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3186      <address><email>jg@freedesktop.org</email></address>
3187    </author>
3188    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3189      <organization abbrev="HP">Hewlett-Packard Company</organization>
3190      <address><email>JeffMogul@acm.org</email></address>
3191    </author>
3192    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3193      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3194      <address><email>henrikn@microsoft.com</email></address>
3195    </author>
3196    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3197      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3198      <address><email>LMM@acm.org</email></address>
3199    </author>
3200    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3201      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3202      <address><email>paulle@microsoft.com</email></address>
3203    </author>
3204    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3205      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3206      <address><email>timbl@w3.org</email></address>
3207    </author>
3208    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3209      <organization abbrev="W3C">World Wide Web Consortium</organization>
3210      <address><email>ylafon@w3.org</email></address>
3211    </author>
3212    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
3213      <address><email>mnot@mnot.net</email></address>
3214    </author>
3215    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3216      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3217      <address><email>julian.reschke@greenbytes.de</email></address>
3218    </author>
3219    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3220  </front>
3221  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
3222  <x:source href="p6-cache.xml" basename="p6-cache"/>
3223</reference>
3224
3225<reference anchor="Part7">
3226  <front>
3227    <title abbrev="HTTP/1.1">HTTP/1.1, part 7: Authentication</title>
3228    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3229      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3230      <address><email>fielding@gbiv.com</email></address>
3231    </author>
3232    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3233      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3234      <address><email>jg@freedesktop.org</email></address>
3235    </author>
3236    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3237      <organization abbrev="HP">Hewlett-Packard Company</organization>
3238      <address><email>JeffMogul@acm.org</email></address>
3239    </author>
3240    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3241      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3242      <address><email>henrikn@microsoft.com</email></address>
3243    </author>
3244    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3245      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3246      <address><email>LMM@acm.org</email></address>
3247    </author>
3248    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3249      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3250      <address><email>paulle@microsoft.com</email></address>
3251    </author>
3252    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3253      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3254      <address><email>timbl@w3.org</email></address>
3255    </author>
3256    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3257      <organization abbrev="W3C">World Wide Web Consortium</organization>
3258      <address><email>ylafon@w3.org</email></address>
3259    </author>
3260    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3261      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3262      <address><email>julian.reschke@greenbytes.de</email></address>
3263    </author>
3264    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3265  </front>
3266  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p7-auth-&ID-VERSION;"/>
3267  <x:source href="p7-auth.xml" basename="p7-auth"/>
3268</reference>
3269
3270<reference anchor="RFC2119">
3271  <front>
3272    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
3273    <author initials="S." surname="Bradner" fullname="Scott Bradner">
3274      <organization>Harvard University</organization>
3275      <address><email>sob@harvard.edu</email></address>
3276    </author>
3277    <date month="March" year="1997"/>
3278  </front>
3279  <seriesInfo name="BCP" value="14"/>
3280  <seriesInfo name="RFC" value="2119"/>
3281</reference>
3282
3283<reference anchor="RFC3986">
3284 <front>
3285  <title abbrev='URI Generic Syntax'>Uniform Resource Identifier (URI): Generic Syntax</title>
3286  <author initials='T.' surname='Berners-Lee' fullname='Tim Berners-Lee'>
3287    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3288    <address>
3289       <email>timbl@w3.org</email>
3290       <uri>http://www.w3.org/People/Berners-Lee/</uri>
3291    </address>
3292  </author>
3293  <author initials='R.' surname='Fielding' fullname='Roy T. Fielding'>
3294    <organization abbrev="Day Software">Day Software</organization>
3295    <address>
3296      <email>fielding@gbiv.com</email>
3297      <uri>http://roy.gbiv.com/</uri>
3298    </address>
3299  </author>
3300  <author initials='L.' surname='Masinter' fullname='Larry Masinter'>
3301    <organization abbrev="Adobe Systems">Adobe Systems Incorporated</organization>
3302    <address>
3303      <email>LMM@acm.org</email>
3304      <uri>http://larry.masinter.net/</uri>
3305    </address>
3306  </author>
3307  <date month='January' year='2005'></date>
3308 </front>
3309 <seriesInfo name="STD" value="66"/>
3310 <seriesInfo name="RFC" value="3986"/>
3311</reference>
3312
3313<reference anchor="RFC5234">
3314  <front>
3315    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
3316    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
3317      <organization>Brandenburg InternetWorking</organization>
3318      <address>
3319        <email>dcrocker@bbiw.net</email>
3320      </address> 
3321    </author>
3322    <author initials="P." surname="Overell" fullname="Paul Overell">
3323      <organization>THUS plc.</organization>
3324      <address>
3325        <email>paul.overell@thus.net</email>
3326      </address>
3327    </author>
3328    <date month="January" year="2008"/>
3329  </front>
3330  <seriesInfo name="STD" value="68"/>
3331  <seriesInfo name="RFC" value="5234"/>
3332</reference>
3333
3334</references>
3335
3336<references title="Informative References">
3337
3338<reference anchor="RFC1945">
3339  <front>
3340    <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1.0</title>
3341    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3342      <organization>MIT, Laboratory for Computer Science</organization>
3343      <address><email>timbl@w3.org</email></address>
3344    </author>
3345    <author initials="R.T." surname="Fielding" fullname="Roy T. Fielding">
3346      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3347      <address><email>fielding@ics.uci.edu</email></address>
3348    </author>
3349    <author initials="H.F." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3350      <organization>W3 Consortium, MIT Laboratory for Computer Science</organization>
3351      <address><email>frystyk@w3.org</email></address>
3352    </author>
3353    <date month="May" year="1996"/>
3354  </front>
3355  <seriesInfo name="RFC" value="1945"/>
3356</reference>
3357
3358<reference anchor="RFC2068">
3359  <front>
3360    <title abbrev="HTTP/1.1">Hypertext Transfer Protocol -- HTTP/1.1</title>
3361    <author initials="R." surname="Fielding" fullname="Roy T. Fielding">
3362      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3363      <address><email>fielding@ics.uci.edu</email></address>
3364    </author>
3365    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3366      <organization>MIT Laboratory for Computer Science</organization>
3367      <address><email>jg@w3.org</email></address>
3368    </author>
3369    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3370      <organization>Digital Equipment Corporation, Western Research Laboratory</organization>
3371      <address><email>mogul@wrl.dec.com</email></address>
3372    </author>
3373    <author initials="H." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3374      <organization>MIT Laboratory for Computer Science</organization>
3375      <address><email>frystyk@w3.org</email></address>
3376    </author>
3377    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3378      <organization>MIT Laboratory for Computer Science</organization>
3379      <address><email>timbl@w3.org</email></address>
3380    </author>
3381    <date month="January" year="1997"/>
3382  </front>
3383  <seriesInfo name="RFC" value="2068"/>
3384</reference>
3385
3386<reference anchor="RFC2616">
3387  <front>
3388    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
3389    <author initials="R." surname="Fielding" fullname="R. Fielding">
3390      <organization>University of California, Irvine</organization>
3391      <address><email>fielding@ics.uci.edu</email></address>
3392    </author>
3393    <author initials="J." surname="Gettys" fullname="J. Gettys">
3394      <organization>W3C</organization>
3395      <address><email>jg@w3.org</email></address>
3396    </author>
3397    <author initials="J." surname="Mogul" fullname="J. Mogul">
3398      <organization>Compaq Computer Corporation</organization>
3399      <address><email>mogul@wrl.dec.com</email></address>
3400    </author>
3401    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
3402      <organization>MIT Laboratory for Computer Science</organization>
3403      <address><email>frystyk@w3.org</email></address>
3404    </author>
3405    <author initials="L." surname="Masinter" fullname="L. Masinter">
3406      <organization>Xerox Corporation</organization>
3407      <address><email>masinter@parc.xerox.com</email></address>
3408    </author>
3409    <author initials="P." surname="Leach" fullname="P. Leach">
3410      <organization>Microsoft Corporation</organization>
3411      <address><email>paulle@microsoft.com</email></address>
3412    </author>
3413    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
3414      <organization>W3C</organization>
3415      <address><email>timbl@w3.org</email></address>
3416    </author>
3417    <date month="June" year="1999"/>
3418  </front>
3419  <seriesInfo name="RFC" value="2616"/>
3420</reference>
3421
3422<reference anchor='RFC2817'>
3423  <front>
3424    <title>Upgrading to TLS Within HTTP/1.1</title>
3425    <author initials='R.' surname='Khare' fullname='R. Khare'>
3426      <organization>4K Associates / UC Irvine</organization>
3427      <address><email>rohit@4K-associates.com</email></address>
3428    </author>
3429    <author initials='S.' surname='Lawrence' fullname='S. Lawrence'>
3430      <organization>Agranat Systems, Inc.</organization>
3431      <address><email>lawrence@agranat.com</email></address>
3432    </author>
3433    <date year='2000' month='May' />
3434  </front>
3435  <seriesInfo name='RFC' value='2817' />
3436</reference>
3437
3438<reference anchor='RFC3864'>
3439  <front>
3440    <title>Registration Procedures for Message Header Fields</title>
3441    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
3442      <organization>Nine by Nine</organization>
3443      <address><email>GK-IETF@ninebynine.org</email></address>
3444    </author>
3445    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
3446      <organization>BEA Systems</organization>
3447      <address><email>mnot@pobox.com</email></address>
3448    </author>
3449    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
3450      <organization>HP Labs</organization>
3451      <address><email>JeffMogul@acm.org</email></address>
3452    </author>
3453    <date year='2004' month='September' />
3454  </front>
3455  <seriesInfo name='BCP' value='90' />
3456  <seriesInfo name='RFC' value='3864' />
3457</reference>
3458
3459<reference anchor='RFC5226'>
3460  <front>
3461    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
3462    <author initials='T.' surname='Narten' fullname='T. Narten'>
3463      <organization>IBM</organization>
3464      <address><email>narten@us.ibm.com</email></address>
3465    </author>
3466    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
3467      <organization>Google</organization>
3468      <address><email>Harald@Alvestrand.no</email></address>
3469    </author>
3470    <date year='2008' month='May' />
3471  </front>
3472  <seriesInfo name='BCP' value='26' />
3473  <seriesInfo name='RFC' value='5226' />
3474</reference>
3475
3476<reference anchor="RFC5322">
3477  <front>
3478    <title>Internet Message Format</title>
3479    <author initials="P." surname="Resnick" fullname="P. Resnick">
3480      <organization>Qualcomm Incorporated</organization>
3481    </author>
3482    <date year="2008" month="October"/>
3483  </front> 
3484  <seriesInfo name="RFC" value="5322"/>
3485</reference>
3486
3487<reference anchor='RFC5789'>
3488  <front>
3489    <title>PATCH Method for HTTP</title>
3490    <author initials='L.' surname='Dusseault' fullname='L. Dusseault'>
3491      <organization>Linden Lab</organization>
3492    </author>
3493    <author initials='J.' surname='Snell' fullname='J. Snell' />
3494    <date year='2010' month='March' />
3495  </front>
3496  <seriesInfo name='RFC' value='5789' />
3497</reference>
3498
3499</references>
3500
3501<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
3502<t>
3503  This document takes over the Status Code Registry, previously defined
3504  in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/>.
3505  (<xref target="status.code.registry"/>)
3506</t>
3507<t>
3508  Clarify definition of POST.
3509  (<xref target="POST"/>)
3510</t>
3511<t>
3512  Remove requirement to handle all Content-* header fields; ban use of
3513  Content-Range with PUT.
3514  (<xref target="PUT"/>)
3515</t>
3516<t>
3517  Take over definition of CONNECT method from <xref target="RFC2817"/>.
3518  (<xref target="CONNECT"/>)
3519</t>
3520<t>
3521  Broadened the definition of 203 (Non-Authoritative Information) to include
3522  cases of payload transformations as well.
3523  (<xref target="status.203"/>)
3524</t>
3525<t>
3526  Failed to consider that there are
3527  many other request methods that are safe to automatically redirect,
3528  and further that the user agent is able to make that determination
3529  based on the request method semantics.
3530  (Sections <xref format="counter" target="status.301"/>,
3531  <xref format="counter" target="status.302"/> and
3532  <xref format="counter" target="status.307"/>)
3533</t>
3534<t>
3535  Deprecate 305 Use Proxy status code, because user agents did not implement it.
3536  It used to indicate that the target resource must be accessed through the
3537  proxy given by the Location field. The Location field gave the URI of the
3538  proxy. The recipient was expected to repeat this single request via the proxy.
3539  (<xref target="status.305"/>)
3540</t>
3541<t>
3542  Define status 426 (Upgrade Required) (this was incorporated from
3543  <xref target="RFC2817"/>).
3544  (<xref target="status.426"/>)
3545</t>
3546<t>
3547  Change ABNF productions for header fields to only define the field value.
3548  (<xref target="header.fields"/>)
3549</t>
3550<t>
3551  Reclassify "Allow" as response header field, removing the option to
3552  specify it in a PUT request.
3553  Relax the server requirement on the contents of the Allow header field and
3554  remove requirement on clients to always trust the header field value.
3555  (<xref target="header.allow"/>)
3556</t>
3557<t>
3558  Correct syntax of Location header field to allow URI references (including
3559  relative references and fragments), as referred symbol "absoluteURI" wasn't
3560  what was expected, and add some clarifications as to when use of fragments
3561  would not be appropriate.
3562  (<xref target="header.location"/>)
3563</t>
3564<t>
3565  Restrict Max-Forwards header field to OPTIONS and TRACE (previously,
3566  extension methods could have used it as well).
3567  (<xref target="header.max-forwards"/>)
3568</t>
3569<t>
3570  Allow Referer field value of "about:blank" as alternative to not specifying it.
3571  (<xref target="header.referer"/>)
3572</t>
3573<t>
3574  In the description of the Server header field, the Via field
3575  was described as a SHOULD. The requirement was and is stated
3576  correctly in the description of the Via header field in &header-via;.
3577  (<xref target="header.server"/>)
3578</t>
3579</section>
3580
3581<?BEGININC p2-semantics.abnf-appendix ?>
3582<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
3583<figure>
3584<artwork type="abnf" name="p2-semantics.parsed-abnf">
3585<x:ref>Allow</x:ref> = [ ( "," / Method ) *( OWS "," [ OWS Method ] ) ]
3586
3587<x:ref>Expect</x:ref> = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] )
3588
3589<x:ref>From</x:ref> = mailbox
3590
3591<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part1], Section 6.1&gt;
3592
3593<x:ref>Location</x:ref> = URI-reference
3594
3595<x:ref>Max-Forwards</x:ref> = 1*DIGIT
3596<x:ref>Method</x:ref> = token
3597
3598<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
3599
3600<x:ref>RWS</x:ref> = &lt;RWS, defined in [Part1], Section 1.2.2&gt;
3601<x:ref>Reason-Phrase</x:ref> = *( WSP / VCHAR / obs-text )
3602<x:ref>Referer</x:ref> = absolute-URI / partial-URI
3603<x:ref>Retry-After</x:ref> = HTTP-date / delta-seconds
3604
3605<x:ref>Server</x:ref> = product *( RWS ( product / comment ) )
3606<x:ref>Status-Code</x:ref> = 3DIGIT
3607
3608<x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in [Part1], Section 2.7&gt;
3609<x:ref>User-Agent</x:ref> = product *( RWS ( product / comment ) )
3610
3611<x:ref>absolute-URI</x:ref> = &lt;absolute-URI, defined in [Part1], Section 2.7&gt;
3612
3613<x:ref>comment</x:ref> = &lt;comment, defined in [Part1], Section 3.2&gt;
3614
3615<x:ref>delta-seconds</x:ref> = 1*DIGIT
3616
3617<x:ref>expect-params</x:ref> = ";" token [ "=" ( token / quoted-string ) ]
3618<x:ref>expectation</x:ref> = "100-continue" / expectation-extension
3619<x:ref>expectation-extension</x:ref> = token [ "=" ( token / quoted-string )
3620 *expect-params ]
3621
3622<x:ref>mailbox</x:ref> = &lt;mailbox, defined in [RFC5322], Section 3.4&gt;
3623
3624<x:ref>obs-text</x:ref> = &lt;obs-text, defined in [Part1], Section 1.2.2&gt;
3625
3626<x:ref>partial-URI</x:ref> = &lt;partial-URI, defined in [Part1], Section 2.7&gt;
3627<x:ref>product</x:ref> = &lt;product, defined in [Part1], Section 6.3&gt;
3628
3629<x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in [Part1], Section 1.2.2&gt;
3630
3631<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 1.2.2&gt;
3632</artwork>
3633</figure>
3634<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
3635; Allow defined but not used
3636; Expect defined but not used
3637; From defined but not used
3638; Location defined but not used
3639; Max-Forwards defined but not used
3640; Reason-Phrase defined but not used
3641; Referer defined but not used
3642; Retry-After defined but not used
3643; Server defined but not used
3644; Status-Code defined but not used
3645; User-Agent defined but not used
3646</artwork></figure></section>
3647<?ENDINC p2-semantics.abnf-appendix ?>
3648
3649<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
3650
3651<section title="Since RFC 2616">
3652<t>
3653  Extracted relevant partitions from <xref target="RFC2616"/>.
3654</t>
3655</section>
3656
3657<section title="Since draft-ietf-httpbis-p2-semantics-00">
3658<t>
3659  Closed issues:
3660  <list style="symbols"> 
3661    <t>
3662      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/5"/>:
3663      "Via is a MUST"
3664      (<eref target="http://purl.org/NET/http-errata#via-must"/>)
3665    </t>
3666    <t>
3667      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/6"/>:
3668      "Fragments allowed in Location"
3669      (<eref target="http://purl.org/NET/http-errata#location-fragments"/>)
3670    </t>
3671    <t>
3672      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3673      "Safe Methods vs Redirection"
3674      (<eref target="http://purl.org/NET/http-errata#saferedirect"/>)
3675    </t>
3676    <t>
3677      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/17"/>:
3678      "Revise description of the POST method"
3679      (<eref target="http://purl.org/NET/http-errata#post"/>)
3680    </t>
3681    <t>
3682      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
3683      "Normative and Informative references"
3684    </t>
3685    <t>
3686      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/42"/>:
3687      "RFC2606 Compliance"
3688    </t>
3689    <t>
3690      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/65"/>:
3691      "Informative references"
3692    </t>
3693    <t>
3694      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/84"/>:
3695      "Redundant cross-references"
3696    </t>
3697  </list>
3698</t>
3699<t>
3700  Other changes:
3701  <list style="symbols"> 
3702    <t>
3703      Move definitions of 304 and 412 condition codes to <xref target="Part4"/>
3704    </t>
3705  </list>
3706</t>
3707</section>
3708
3709<section title="Since draft-ietf-httpbis-p2-semantics-01">
3710<t>
3711  Closed issues:
3712  <list style="symbols"> 
3713    <t>
3714      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/21"/>:
3715      "PUT side effects"
3716    </t>
3717    <t>
3718      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/91"/>:
3719      "Duplicate Host header requirements"
3720    </t>
3721  </list>
3722</t>
3723<t>
3724  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3725  <list style="symbols"> 
3726    <t>
3727      Move "Product Tokens" section (back) into Part 1, as "token" is used
3728      in the definition of the Upgrade header field.
3729    </t>
3730    <t>
3731      Add explicit references to BNF syntax and rules imported from other parts of the specification.
3732    </t>
3733    <t>
3734      Copy definition of delta-seconds from Part6 instead of referencing it.
3735    </t>
3736  </list>
3737</t>
3738</section>
3739
3740<section title="Since draft-ietf-httpbis-p2-semantics-02" anchor="changes.since.02">
3741<t>
3742  Closed issues:
3743  <list style="symbols"> 
3744    <t>
3745      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/24"/>:
3746      "Requiring Allow in 405 responses"
3747    </t>
3748    <t>
3749      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/59"/>:
3750      "Status Code Registry"
3751    </t>
3752    <t>
3753      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/61"/>:
3754      "Redirection vs. Location"
3755    </t>
3756    <t>
3757      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/70"/>:
3758      "Cacheability of 303 response"
3759    </t>
3760    <t>
3761      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/76"/>:
3762      "305 Use Proxy"
3763    </t>
3764    <t>
3765      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/105"/>:
3766      "Classification for Allow header"
3767    </t>
3768    <t>
3769      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
3770      "PUT - 'store under' vs 'store at'"
3771    </t>
3772  </list>
3773</t>
3774<t>
3775  Ongoing work on IANA Message Header Field Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
3776  <list style="symbols"> 
3777    <t>
3778      Reference RFC 3984, and update header field registrations for headers defined
3779      in this document.
3780    </t>
3781  </list>
3782</t>
3783<t>
3784  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3785  <list style="symbols"> 
3786    <t>
3787      Replace string literals when the string really is case-sensitive (method).
3788    </t>
3789  </list>
3790</t>
3791</section>
3792
3793<section title="Since draft-ietf-httpbis-p2-semantics-03" anchor="changes.since.03">
3794<t>
3795  Closed issues:
3796  <list style="symbols"> 
3797    <t>
3798      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/98"/>:
3799      "OPTIONS request bodies"
3800    </t>
3801    <t>
3802      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/119"/>:
3803      "Description of CONNECT should refer to RFC2817"
3804    </t>
3805    <t>
3806      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/125"/>:
3807      "Location Content-Location reference request/response mixup"
3808    </t>
3809  </list>
3810</t>
3811<t>
3812  Ongoing work on Method Registry (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/72"/>):
3813  <list style="symbols"> 
3814    <t>
3815      Added initial proposal for registration process, plus initial
3816      content (non-HTTP/1.1 methods to be added by a separate specification).
3817    </t>
3818  </list>
3819</t>
3820</section>
3821
3822<section title="Since draft-ietf-httpbis-p2-semantics-04" anchor="changes.since.04">
3823<t>
3824  Closed issues:
3825  <list style="symbols"> 
3826    <t>
3827      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/103"/>:
3828      "Content-*"
3829    </t>
3830    <t>
3831      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/132"/>:
3832      "RFC 2822 is updated by RFC 5322"
3833    </t>
3834  </list>
3835</t>
3836<t>
3837  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3838  <list style="symbols"> 
3839    <t>
3840      Use "/" instead of "|" for alternatives.
3841    </t>
3842    <t>
3843      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
3844      whitespace ("OWS") and required whitespace ("RWS").
3845    </t>
3846    <t>
3847      Rewrite ABNFs to spell out whitespace rules, factor out
3848      header field value format definitions.
3849    </t>
3850  </list>
3851</t>
3852</section>
3853
3854<section title="Since draft-ietf-httpbis-p2-semantics-05" anchor="changes.since.05">
3855<t>
3856  Closed issues:
3857  <list style="symbols"> 
3858    <t>
3859      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/94"/>:
3860      "Reason-Phrase BNF"
3861    </t>
3862  </list>
3863</t>
3864<t>
3865  Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3866  <list style="symbols"> 
3867    <t>
3868      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
3869    </t>
3870  </list>
3871</t>
3872</section>
3873
3874<section title="Since draft-ietf-httpbis-p2-semantics-06" anchor="changes.since.06">
3875<t>
3876  Closed issues:
3877  <list style="symbols"> 
3878    <t>
3879      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/144"/>:
3880      "Clarify when Referer is sent"
3881    </t>
3882    <t>
3883      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/164"/>:
3884      "status codes vs methods"
3885    </t>
3886    <t>
3887      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/170"/>:
3888      "Do not require "updates" relation for specs that register status codes or method names"
3889    </t>
3890  </list>
3891</t>
3892</section>
3893
3894<section title="Since draft-ietf-httpbis-p2-semantics-07" anchor="changes.since.07">
3895<t>
3896  Closed issues:
3897  <list style="symbols"> 
3898    <t>
3899      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/27"/>:
3900      "Idempotency"
3901    </t>
3902    <t>
3903      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/33"/>:
3904      "TRACE security considerations"
3905    </t>
3906    <t>
3907      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/110"/>:
3908      "Clarify rules for determining what entities a response carries"
3909    </t>
3910    <t>
3911      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/140"/>:
3912      "update note citing RFC 1945 and 2068"
3913    </t>
3914    <t>
3915      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/182"/>:
3916      "update note about redirect limit"
3917    </t>
3918    <t>
3919      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/191"/>:
3920      "Location header ABNF should use 'URI'"
3921    </t>
3922    <t>
3923      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/192"/>:
3924      "fragments in Location vs status 303"
3925    </t>
3926    <t>
3927      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/198"/>:
3928      "move IANA registrations for optional status codes"
3929    </t>
3930  </list>
3931</t>
3932<t>
3933  Partly resolved issues:
3934  <list style="symbols"> 
3935    <t>
3936      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/171"/>:
3937      "Are OPTIONS and TRACE safe?"
3938    </t>
3939  </list>
3940</t>
3941</section>
3942
3943<section title="Since draft-ietf-httpbis-p2-semantics-08" anchor="changes.since.08">
3944<t>
3945  Closed issues:
3946  <list style="symbols"> 
3947    <t>
3948      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3949      "Safe Methods vs Redirection" (we missed the introduction to the 3xx
3950      status codes when fixing this previously)
3951    </t>
3952  </list>
3953</t>
3954</section>
3955
3956<section title="Since draft-ietf-httpbis-p2-semantics-09" anchor="changes.since.09">
3957<t>
3958  Closed issues:
3959  <list style="symbols"> 
3960    <t>
3961      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/43"/>:
3962      "Fragment combination / precedence during redirects"
3963    </t>
3964  </list>
3965</t>
3966<t>
3967  Partly resolved issues:
3968  <list style="symbols"> 
3969    <t>
3970      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/185"/>:
3971      "Location header payload handling"
3972    </t>
3973    <t>
3974      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/196"/>:
3975      "Term for the requested resource's URI"
3976    </t>
3977  </list>
3978</t>
3979</section>
3980
3981<section title="Since draft-ietf-httpbis-p2-semantics-10" anchor="changes.since.10">
3982<t>
3983  Closed issues:
3984  <list style="symbols"> 
3985    <t>
3986      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/69"/>:
3987      "Clarify 'Requested Variant'"
3988    </t>
3989    <t>
3990      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/109"/>:
3991      "Clarify entity / representation / variant terminology"
3992    </t>
3993    <t>
3994      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/139"/>:
3995      "Methods and Caching"
3996    </t>
3997    <t>
3998      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/190"/>:
3999      "OPTIONS vs Max-Forwards"
4000    </t>
4001    <t>
4002      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/199"/>:
4003      "Status codes and caching"
4004    </t>
4005    <t>
4006      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>:
4007      "consider removing the 'changes from 2068' sections"
4008    </t>
4009  </list>
4010</t>
4011</section>
4012
4013<section title="Since draft-ietf-httpbis-p2-semantics-11" anchor="changes.since.11">
4014<t>
4015  Closed issues:
4016  <list style="symbols"> 
4017    <t>
4018      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/229"/>:
4019      "Considerations for new status codes"
4020    </t>
4021    <t>
4022      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/230"/>:
4023      "Considerations for new methods"
4024    </t>
4025    <t>
4026      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/232"/>:
4027      "User-Agent guidelines" (relating to the 'User-Agent' header field)
4028    </t>
4029  </list>
4030</t>
4031</section>
4032
4033<section title="Since draft-ietf-httpbis-p2-semantics-12" anchor="changes.since.12">
4034<t>
4035  Closed issues:
4036  <list style="symbols"> 
4037    <t>
4038      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/43"/>:
4039      "Fragment combination / precedence during redirects" (added warning
4040      about having a fragid on the redirect may cause inconvenience in
4041      some cases)
4042    </t>
4043    <t>
4044      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/79"/>:
4045      "Content-* vs. PUT"
4046    </t>
4047    <t>
4048      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/88"/>:
4049      "205 Bodies"
4050    </t>
4051    <t>
4052      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/102"/>:
4053      "Understanding Content-* on non-PUT requests"
4054    </t>
4055    <t>
4056      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/103"/>:
4057      "Content-*"
4058    </t>
4059    <t>
4060      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/104"/>:
4061      "Header type defaulting"
4062    </t>
4063    <t>
4064      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
4065      "PUT - 'store under' vs 'store at'"
4066    </t>
4067    <t>
4068      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/137"/>:
4069      "duplicate ABNF for Reason-Phrase"
4070    </t>
4071    <t>
4072      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/180"/>:
4073      "Note special status of Content-* prefix in header registration procedures"
4074    </t>
4075    <t>
4076      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/203"/>:
4077      "Max-Forwards vs extension methods"
4078    </t>
4079    <t>
4080      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/213"/>:
4081      "What is the value space of HTTP status codes?" (actually fixed in
4082      draft-ietf-httpbis-p2-semantics-11)
4083    </t>
4084    <t>
4085      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/224"/>:
4086      "Header Classification"
4087    </t>
4088    <t>
4089      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/225"/>:
4090      "PUT side effect: invalidation or just stale?"
4091    </t>
4092    <t>
4093      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/226"/>:
4094      "proxies not supporting certain methods"
4095    </t>
4096    <t>
4097      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/239"/>:
4098      "Migrate CONNECT from RFC2817 to p2"
4099    </t>
4100    <t>
4101      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/240"/>:
4102      "Migrate Upgrade details from RFC2817"
4103    </t>
4104    <t>
4105      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/267"/>:
4106      "clarify PUT semantics'"
4107    </t>
4108    <t>
4109      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/275"/>:
4110      "duplicate ABNF for 'Method'"
4111    </t>
4112    <t>
4113      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/276"/>:
4114      "untangle ABNFs for header fields"
4115    </t>
4116  </list>
4117</t>
4118</section>
4119
4120<section title="Since draft-ietf-httpbis-p2-semantics-13" anchor="changes.since.13">
4121<t>
4122  Closed issues:
4123  <list style="symbols"> 
4124    <t>
4125      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/276"/>:
4126      "untangle ABNFs for header fields"
4127    </t>
4128    <t>
4129      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/251"/>:
4130      "message-body in CONNECT request"
4131    </t>
4132  </list>
4133</t>
4134</section>
4135
4136<section title="Since draft-ietf-httpbis-p2-semantics-14" anchor="changes.since.14">
4137<t>
4138  Closed issues:
4139  <list style="symbols"> 
4140    <t>
4141      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/255"/>:
4142      "Clarify status code for rate limiting"
4143    </t>
4144    <t>
4145      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/294"/>:
4146      "clarify 403 forbidden"
4147    </t>
4148    <t>
4149      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/296"/>:
4150      "Clarify 203 Non-Authoritative Information"
4151    </t>
4152    <t>
4153      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/298"/>:
4154      "update default reason phrase for 413"
4155    </t>
4156  </list>
4157</t>
4158</section>
4159
4160<section title="Since draft-ietf-httpbis-p2-semantics-15" anchor="changes.since.15">
4161<t>
4162  Closed issues:
4163  <list style="symbols"> 
4164    <t>
4165      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/285"/>:
4166      "Strength of requirements on Accept re: 406"
4167    </t>
4168  </list>
4169</t>
4170</section>
4171</section>
4172
4173</back>
4174</rfc>
Note: See TracBrowser for help on using the repository browser.