source: draft-ietf-httpbis/latest/p2-semantics.xml @ 1321

Last change on this file since 1321 was 1321, checked in by julian.reschke@…, 8 years ago

bump up document dates, update to latest version of rfc2629.xslt

  • Property svn:eol-style set to native
File size: 169.5 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 p4-status-codes            "<xref target='Part4' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
77  <!ENTITY p5-status-codes            "<xref target='Part5' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
78  <!ENTITY p7-status-codes            "<xref target='Part7' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
79  <!ENTITY p6-heuristic               "<xref target='Part6' x:rel='#heuristic.freshness' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
80  <!ENTITY p6-explicit                "<xref target='Part6' x:rel='#calculating.freshness.lifetime' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
81  <!ENTITY p6-invalid                 "<xref target='Part6' x:rel='#invalidation.after.updates.or.deletions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
82]>
83<?rfc toc="yes" ?>
84<?rfc symrefs="yes" ?>
85<?rfc sortrefs="yes" ?>
86<?rfc compact="yes"?>
87<?rfc subcompact="no" ?>
88<?rfc linkmailto="no" ?>
89<?rfc editing="no" ?>
90<?rfc comments="yes"?>
91<?rfc inline="yes"?>
92<?rfc rfcedstyle="yes"?>
93<?rfc-ext allow-markup-in-artwork="yes" ?>
94<?rfc-ext include-references-in-index="yes" ?>
95<rfc obsoletes="2616" updates="2817" category="std" x:maturity-level="draft"
96     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"
97     xmlns:x='http://purl.org/net/xml2rfc/ext'
98     xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
99<front>
100
101  <title abbrev="HTTP/1.1, Part 2">HTTP/1.1, part 2: Message Semantics</title>
102
103  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
104    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
105    <address>
106      <postal>
107        <street>345 Park Ave</street>
108        <city>San Jose</city>
109        <region>CA</region>
110        <code>95110</code>
111        <country>USA</country>
112      </postal>
113      <email>fielding@gbiv.com</email>
114      <uri>http://roy.gbiv.com/</uri>
115    </address>
116  </author>
117
118  <author initials="J." surname="Gettys" fullname="Jim Gettys">
119    <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
120    <address>
121      <postal>
122        <street>21 Oak Knoll Road</street>
123        <city>Carlisle</city>
124        <region>MA</region>
125        <code>01741</code>
126        <country>USA</country>
127      </postal>
128      <email>jg@freedesktop.org</email>
129      <uri>http://gettys.wordpress.com/</uri>
130    </address>
131  </author>
132 
133  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
134    <organization abbrev="HP">Hewlett-Packard Company</organization>
135    <address>
136      <postal>
137        <street>HP Labs, Large Scale Systems Group</street>
138        <street>1501 Page Mill Road, MS 1177</street>
139        <city>Palo Alto</city>
140        <region>CA</region>
141        <code>94304</code>
142        <country>USA</country>
143      </postal>
144      <email>JeffMogul@acm.org</email>
145    </address>
146  </author>
147
148  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
149    <organization abbrev="Microsoft">Microsoft Corporation</organization>
150    <address>
151      <postal>
152        <street>1 Microsoft Way</street>
153        <city>Redmond</city>
154        <region>WA</region>
155        <code>98052</code>
156        <country>USA</country>
157      </postal>
158      <email>henrikn@microsoft.com</email>
159    </address>
160  </author>
161
162  <author initials="L." surname="Masinter" fullname="Larry Masinter">
163    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
164    <address>
165      <postal>
166        <street>345 Park Ave</street>
167        <city>San Jose</city>
168        <region>CA</region>
169        <code>95110</code>
170        <country>USA</country>
171      </postal>
172      <email>LMM@acm.org</email>
173      <uri>http://larry.masinter.net/</uri>
174    </address>
175  </author>
176 
177  <author initials="P." surname="Leach" fullname="Paul J. Leach">
178    <organization abbrev="Microsoft">Microsoft Corporation</organization>
179    <address>
180      <postal>
181        <street>1 Microsoft Way</street>
182        <city>Redmond</city>
183        <region>WA</region>
184        <code>98052</code>
185      </postal>
186      <email>paulle@microsoft.com</email>
187    </address>
188  </author>
189   
190  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
191    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
192    <address>
193      <postal>
194        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
195        <street>The Stata Center, Building 32</street>
196        <street>32 Vassar Street</street>
197        <city>Cambridge</city>
198        <region>MA</region>
199        <code>02139</code>
200        <country>USA</country>
201      </postal>
202      <email>timbl@w3.org</email>
203      <uri>http://www.w3.org/People/Berners-Lee/</uri>
204    </address>
205  </author>
206
207  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
208    <organization abbrev="W3C">World Wide Web Consortium</organization>
209    <address>
210      <postal>
211        <street>W3C / ERCIM</street>
212        <street>2004, rte des Lucioles</street>
213        <city>Sophia-Antipolis</city>
214        <region>AM</region>
215        <code>06902</code>
216        <country>France</country>
217      </postal>
218      <email>ylafon@w3.org</email>
219      <uri>http://www.raubacapeu.net/people/yves/</uri>
220    </address>
221  </author>
222
223  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
224    <organization abbrev="greenbytes">greenbytes GmbH</organization>
225    <address>
226      <postal>
227        <street>Hafenweg 16</street>
228        <city>Muenster</city><region>NW</region><code>48155</code>
229        <country>Germany</country>
230      </postal>
231      <phone>+49 251 2807760</phone>
232      <facsimile>+49 251 2807761</facsimile>
233      <email>julian.reschke@greenbytes.de</email>
234      <uri>http://greenbytes.de/tech/webdav/</uri>
235    </address>
236  </author>
237
238  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
239  <workgroup>HTTPbis Working Group</workgroup>
240
241<abstract>
242<t>
243   The Hypertext Transfer Protocol (HTTP) is an application-level
244   protocol for distributed, collaborative, hypermedia information
245   systems. HTTP has been in use by the World Wide Web global information
246   initiative since 1990. This document is Part 2 of the seven-part specification
247   that defines the protocol referred to as "HTTP/1.1" and, taken together,
248   obsoletes RFC 2616.  Part 2 defines the semantics of HTTP messages
249   as expressed by request methods, request header fields, response status codes,
250   and response header fields.
251</t>
252</abstract>
253
254<note title="Editorial Note (To be removed by RFC Editor)">
255  <t>
256    Discussion of this draft should take place on the HTTPBIS working group
257    mailing list (ietf-http-wg@w3.org), which is archived at
258    <eref target="http://lists.w3.org/Archives/Public/ietf-http-wg/"/>.
259  </t>
260  <t>
261    The current issues list is at
262    <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/> and related
263    documents (including fancy diffs) can be found at
264    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
265  </t>
266  <t>
267    The changes in this draft are summarized in <xref target="changes.since.14"/>.
268  </t>
269</note>
270</front>
271<middle>
272<section title="Introduction" anchor="introduction">
273<t>
274   This document defines HTTP/1.1 request and response semantics.  Each HTTP
275   message, as defined in &messaging;, is in the form of either a request or
276   a response.  An HTTP server listens on a connection for HTTP requests and
277   responds to each request, in the order received on that connection, with
278   one or more HTTP response messages.  This document defines the commonly
279   agreed upon semantics of the HTTP uniform interface, the intentions defined
280   by each request method, and the various response messages that might be
281   expected as a result of applying that method to the target resource.
282</t>
283<t>
284   This document is currently disorganized in order to minimize the changes
285   between drafts and enable reviewers to see the smaller errata changes.
286   A future draft will reorganize the sections to better reflect the content.
287   In particular, the sections will be ordered according to the typical
288   processing of an HTTP request message (after message parsing): resource
289   mapping, methods, request modifying header fields, response status,
290   status modifying header fields, and resource metadata.  The current mess
291   reflects how widely dispersed these topics and associated requirements
292   had become in <xref target="RFC2616"/>.
293</t>
294
295<section title="Requirements" anchor="intro.requirements">
296<t>
297   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
298   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
299   document are to be interpreted as described in <xref target="RFC2119"/>.
300</t>
301<t>
302   An implementation is not compliant if it fails to satisfy one or more
303   of the "MUST" or "REQUIRED" level requirements for the protocols it
304   implements. An implementation that satisfies all the "MUST" or "REQUIRED"
305   level and all the "SHOULD" level requirements for its protocols is said
306   to be "unconditionally compliant"; one that satisfies all the "MUST"
307   level requirements but not all the "SHOULD" level requirements for its
308   protocols is said to be "conditionally compliant".
309</t>
310</section>
311
312<section title="Syntax Notation" anchor="notation">
313  <x:anchor-alias value="CR"/>
314  <x:anchor-alias value="DIGIT"/>
315  <x:anchor-alias value="LF"/>
316  <x:anchor-alias value="VCHAR"/>
317  <x:anchor-alias value="WSP"/>
318<t>
319  This specification uses the ABNF syntax defined in &notation; (which
320  extends the syntax defined in <xref target="RFC5234"/> with a list rule).
321  <xref target="collected.abnf"/> shows the collected ABNF, with the list
322  rule expanded.
323</t>
324<t>
325  The following core rules are included by
326  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
327  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
328  DIGIT (decimal 0-9), DQUOTE (double quote),
329  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
330  OCTET (any 8-bit sequence of data), SP (space),
331  VCHAR (any visible USASCII character),
332  and WSP (whitespace).
333</t>
334
335<section title="Core Rules" anchor="core.rules">
336  <x:anchor-alias value="obs-text"/>
337  <x:anchor-alias value="quoted-string"/>
338  <x:anchor-alias value="token"/>
339  <x:anchor-alias value="OWS"/>
340  <x:anchor-alias value="RWS"/>
341<t>
342  The core rules below are defined in &basic-rules;:
343</t>
344<figure><artwork type="abnf2616">
345  <x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in &basic-rules;&gt;
346  <x:ref>token</x:ref>         = &lt;token, defined in &basic-rules;&gt;
347  <x:ref>OWS</x:ref>           = &lt;OWS, defined in &basic-rules;&gt;
348  <x:ref>RWS</x:ref>           = &lt;RWS, defined in &basic-rules;&gt;
349  <x:ref>obs-text</x:ref>      = &lt;obs-text, defined in &basic-rules;&gt;
350</artwork></figure>
351</section>
352
353<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
354  <x:anchor-alias value="absolute-URI"/>
355  <x:anchor-alias value="comment"/>
356  <x:anchor-alias value="HTTP-date"/>
357  <x:anchor-alias value="partial-URI"/>
358  <x:anchor-alias value="product"/>
359  <x:anchor-alias value="URI-reference"/>
360<t>
361  The ABNF rules below are defined in other parts:
362</t>
363<figure><!--Part1--><artwork type="abnf2616">
364  <x:ref>absolute-URI</x:ref>  = &lt;absolute-URI, defined in &uri;&gt;
365  <x:ref>comment</x:ref>       = &lt;comment, defined in &header-fields;&gt;
366  <x:ref>HTTP-date</x:ref>     = &lt;HTTP-date, defined in &full-date;&gt;
367  <x:ref>partial-URI</x:ref>   = &lt;partial-URI, defined in &uri;&gt;
368  <x:ref>product</x:ref>       = &lt;product, defined in &product-tokens;&gt;
369  <x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in &uri;&gt;
370</artwork></figure>
371</section>
372</section>
373</section>
374
375<section title="Method" anchor="method">
376  <x:anchor-alias value="Method"/>
377  <x:anchor-alias value="extension-method"/>
378<t>
379   The Method token indicates the request method to be performed on the target
380   resource (&effective-request-uri;). The method is case-sensitive.
381</t>
382<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Method"/>
383  <x:ref>Method</x:ref>         = <x:ref>token</x:ref>
384</artwork></figure>
385<t>
386   The list of methods allowed by a resource can be specified in an
387   Allow header field (<xref target="header.allow"/>). The status code of the response
388   always notifies the client whether a method is currently allowed on a
389   resource, since the set of allowed methods can change dynamically. An
390   origin server &SHOULD; respond with the status code 405 (Method Not Allowed)
391   if the method is known by the origin server but not allowed for the
392   resource, and 501 (Not Implemented) if the method is
393   unrecognized or not implemented by the origin server. The methods GET
394   and HEAD &MUST; be supported by all general-purpose servers. All other
395   methods are &OPTIONAL;; however, if the above methods are implemented,
396   they &MUST; be implemented with the same semantics as those specified
397   in <xref target="method.definitions"/>.
398</t>
399
400<section title="Overview of Methods" anchor="overview.of.methods">
401<t>
402  The methods listed below are defined in <xref target="method.definitions"/>.
403</t>
404<texttable align="left">
405  <ttcol>Method Name</ttcol><ttcol>Defined in...</ttcol>
406 
407  <c>OPTIONS</c> <c><xref target="OPTIONS"/></c>
408  <c>GET</c> <c><xref target="GET"/></c>
409  <c>HEAD</c> <c><xref target="HEAD"/></c>
410  <c>POST</c> <c><xref target="POST"/></c>
411  <c>PUT</c> <c><xref target="PUT"/></c>
412  <c>DELETE</c> <c><xref target="DELETE"/></c>
413  <c>TRACE</c> <c><xref target="TRACE"/></c>
414  <c>CONNECT</c> <c><xref target="CONNECT"/></c>
415</texttable>
416<t>
417  Note that this list is not exhaustive &mdash; it does not include request methods defined
418  in other specifications.
419</t>
420</section>
421
422<section title="Method Registry" anchor="method.registry">
423<t>
424  The HTTP Method Registry defines the name space for the Method token in the
425  Request line of an HTTP request.
426</t>
427<t>
428  Registrations &MUST; include the following fields:
429  <list style="symbols">
430    <t>Method Name (see <xref target="method"/>)</t>
431    <t>Safe ("yes" or "no", see <xref target="safe.methods"/>)</t>
432    <t>Pointer to specification text</t>
433  </list>
434</t>
435<t>
436  Values to be added to this name space are subject to IETF review
437  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
438</t>
439<t>
440  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-methods"/>.
441</t>
442
443<section title="Considerations for New Methods" anchor="considerations.for.new.methods">
444<t>
445   When it is necessary to express new semantics for a HTTP request that
446   aren't specific to a single application or media type, and currently defined
447   methods are inadequate, it may be appropriate to register a new method.
448</t>
449<t>
450   HTTP methods are generic; that is, they are potentially applicable to any
451   resource, not just one particular media type, "type" of resource, or
452   application. As such, it is preferred that new HTTP methods be registered
453   in a document that isn't specific to a single application, so that this is
454   clear.
455</t>
456<t>
457   Due to the parsing rules defined in &message-body;, definitions of HTTP
458   methods cannot prohibit the presence of a message-body on either the request
459   or the response message (with responses to HEAD requests being the single
460   exception). Definitions of new methods cannot change this rule, but they can
461   specify that only zero-length bodies (as opposed to absent bodies) are allowed.
462</t>
463<t>
464   New method definitions need to indicate whether they are safe (<xref
465   target="safe.methods"/>), what semantics (if any) the request body has,
466   and whether they are idempotent (<xref target="idempotent.methods"/>).
467   They also need to state whether they can be cached (&caching;); in
468   particular what conditions a cache may store the response, and under what
469   conditions such a stored response may be used to satisfy a subsequent
470   request.
471</t>
472</section>
473
474</section>
475</section>
476
477<section title="Request Header Fields" anchor="request.header.fields">
478  <x:anchor-alias value="request-header"/>
479<t>
480   The request header fields allow the client to pass additional
481   information about the request, and about the client itself, to the
482   server. These fields act as request modifiers, with semantics
483   equivalent to the parameters on a programming language method
484   invocation.
485</t>
486<texttable align="left">
487  <ttcol>Header Field Name</ttcol>
488  <ttcol>Defined in...</ttcol>
489
490  <c>Accept</c> <c>&header-accept;</c>
491  <c>Accept-Charset</c> <c>&header-accept-charset;</c>
492  <c>Accept-Encoding</c> <c>&header-accept-encoding;</c>
493  <c>Accept-Language</c> <c>&header-accept-language;</c>
494  <c>Authorization</c> <c>&header-authorization;</c>
495  <c>Expect</c> <c><xref target="header.expect"/></c>
496  <c>From</c> <c><xref target="header.from"/></c>
497  <c>Host</c> <c>&header-host;</c>
498  <c>If-Match</c> <c>&header-if-match;</c>
499  <c>If-Modified-Since</c> <c>&header-if-modified-since;</c>
500  <c>If-None-Match</c> <c>&header-if-none-match;</c>
501  <c>If-Range</c> <c>&header-if-range;</c>
502  <c>If-Unmodified-Since</c> <c>&header-if-unmodified-since;</c>
503  <c>Max-Forwards</c> <c><xref target="header.max-forwards"/></c>
504  <c>Proxy-Authorization</c> <c>&header-proxy-authorization;</c>
505  <c>Range</c> <c>&header-range;</c>
506  <c>Referer</c> <c><xref target="header.referer"/></c>
507  <c>TE</c> <c>&header-te;</c>
508  <c>User-Agent</c> <c><xref target="header.user-agent"/></c>
509</texttable>
510</section>
511
512<section title="Status Code and Reason Phrase" anchor="status.code.and.reason.phrase">
513  <x:anchor-alias value="Reason-Phrase"/>
514  <x:anchor-alias value="Status-Code"/>
515  <x:anchor-alias value="extension-code"/>
516<t>
517   The Status-Code element is a 3-digit integer result code of the attempt to
518   understand and satisfy the request.
519</t>
520<t>
521   The Reason-Phrase is intended to give a short textual description of the
522   Status-Code and is intended for a human user. The client does not need
523   to examine or display the Reason-Phrase.
524</t>
525<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"/>
526  <x:ref>Status-Code</x:ref>    = 3<x:ref>DIGIT</x:ref>
527  <x:ref>Reason-Phrase</x:ref>  = *( <x:ref>WSP</x:ref> / <x:ref>VCHAR</x:ref> / <x:ref>obs-text</x:ref> )
528</artwork></figure>
529<t>
530   HTTP status codes are extensible. HTTP applications are not required
531   to understand the meaning of all registered status codes, though such
532   understanding is obviously desirable. However, applications &MUST;
533   understand the class of any status code, as indicated by the first
534   digit, and treat any unrecognized response as being equivalent to the
535   x00 status code of that class, with the exception that an
536   unrecognized response &MUST-NOT; be cached. For example, if an
537   unrecognized status code of 431 is received by the client, it can
538   safely assume that there was something wrong with its request and
539   treat the response as if it had received a 400 status code. In such
540   cases, user agents &SHOULD; present to the user the representation enclosed
541   with the response, since that representation is likely to include human-readable
542   information which will explain the unusual status.
543</t>
544
545<section title="Overview of Status Codes" anchor="overview.of.status.codes">
546<t> 
547   The status codes listed below are defined in <xref target="status.codes"/>
548   of this specification, &p4-status-codes;, &p5-status-codes;, and &p7-status-codes;.
549   The reason phrases listed here are only recommendations &mdash; they can be
550   replaced by local equivalents without affecting the protocol.
551</t>
552<texttable align="left">
553  <ttcol>Status-Code</ttcol>
554  <ttcol>Reason-Phrase</ttcol>
555  <ttcol>Defined in...</ttcol>
556 
557  <c>100</c> <c>Continue</c> <c><xref target="status.100"/></c>
558  <c>101</c> <c>Switching Protocols</c> <c><xref target="status.101"/></c>
559
560  <c>200</c> <c>OK</c> <c><xref target="status.200"/></c>
561  <c>201</c> <c>Created</c> <c><xref target="status.201"/></c>
562  <c>202</c> <c>Accepted</c> <c><xref target="status.202"/></c>
563  <c>203</c> <c>Non-Authoritative Information</c> <c><xref target="status.203"/></c>
564  <c>204</c> <c>No Content</c> <c><xref target="status.204"/></c>
565  <c>205</c> <c>Reset Content</c> <c><xref target="status.205"/></c>
566  <c>206</c> <c>Partial Content</c> <c>&status-206;</c>
567
568  <c>300</c> <c>Multiple Choices</c> <c><xref target="status.300"/></c>
569  <c>301</c> <c>Moved Permanently</c> <c><xref target="status.301"/></c>
570  <c>302</c> <c>Found</c> <c><xref target="status.302"/></c>
571  <c>303</c> <c>See Other</c> <c><xref target="status.303"/></c>
572  <c>304</c> <c>Not Modified</c> <c>&status-304;</c>
573  <c>305</c> <c>Use Proxy</c> <c><xref target="status.305"/></c>
574  <c>307</c> <c>Temporary Redirect</c> <c><xref target="status.307"/></c>
575
576  <c>400</c> <c>Bad Request</c> <c><xref target="status.400"/></c>
577  <c>401</c> <c>Unauthorized</c> <c>&status-401;</c>
578  <c>402</c> <c>Payment Required</c> <c><xref target="status.402"/></c>
579  <c>403</c> <c>Forbidden</c> <c><xref target="status.403"/></c>
580  <c>404</c> <c>Not Found</c> <c><xref target="status.404"/></c>
581  <c>405</c> <c>Method Not Allowed</c> <c><xref target="status.405"/></c>
582  <c>406</c> <c>Not Acceptable</c> <c><xref target="status.406"/></c>
583  <c>407</c> <c>Proxy Authentication Required</c> <c>&status-407;</c>
584  <c>408</c> <c>Request Time-out</c> <c><xref target="status.408"/></c>
585  <c>409</c> <c>Conflict</c> <c><xref target="status.409"/></c>
586  <c>410</c> <c>Gone</c> <c><xref target="status.410"/></c>
587  <c>411</c> <c>Length Required</c> <c><xref target="status.411"/></c>
588  <c>412</c> <c>Precondition Failed</c> <c>&status-412;</c>
589  <c>413</c> <c>Request Entity Too Large</c> <c><xref target="status.413"/></c>
590  <c>414</c> <c>URI Too Long</c> <c><xref target="status.414"/></c>
591  <c>415</c> <c>Unsupported Media Type</c> <c><xref target="status.415"/></c>
592  <c>416</c> <c>Requested range not satisfiable</c> <c>&status-416;</c>
593  <c>417</c> <c>Expectation Failed</c> <c><xref target="status.417"/></c>
594  <c>426</c> <c>Upgrade Required</c> <c><xref target="status.426"/></c>
595
596  <c>500</c> <c>Internal Server Error</c> <c><xref target="status.500"/></c>
597  <c>501</c> <c>Not Implemented</c> <c><xref target="status.501"/></c>
598  <c>502</c> <c>Bad Gateway</c> <c><xref target="status.502"/></c>
599  <c>503</c> <c>Service Unavailable</c> <c><xref target="status.503"/></c>
600  <c>504</c> <c>Gateway Time-out</c> <c><xref target="status.504"/></c>
601  <c>505</c> <c>HTTP Version not supported</c> <c><xref target="status.505"/></c>
602</texttable>
603<t>
604   Note that this list is not exhaustive &mdash; it does not include
605   extension status codes defined in other specifications.
606</t>
607</section>
608
609<section title="Status Code Registry" anchor="status.code.registry">
610<t>
611  The HTTP Status Code Registry defines the name space for the Status-Code
612  token in the Status-Line of an HTTP response.
613</t>
614<t>
615  Values to be added to this name space are subject to IETF review
616  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
617</t>
618<t>
619  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-status-codes"/>.
620</t>
621
622<section title="Considerations for New Status Codes" anchor="considerations.for.new.status.codes">
623<t>
624   When it is necessary to express new semantics for a HTTP response that
625   aren't specific to a single application or media type, and currently defined
626   status codes are inadequate, a new status code can be registered.
627</t>
628<t>
629   HTTP status codes are generic; that is, they are potentially applicable to
630   any resource, not just one particular media type, "type" of resource, or
631   application. As such, it is preferred that new HTTP status codes be
632   registered in a document that isn't specific to a single application, so
633   that this is clear.
634</t>
635<t>
636   Definitions of new HTTP status codes typically explain the request
637   conditions that produce a response containing the status code (e.g.,
638   combinations of request headers and/or method(s)), along with any
639   interactions with response headers (e.g., those that are required, those
640   that modify the semantics of the response).
641</t>
642<t>
643   New HTTP status codes are required to fall under one of the categories
644   defined in <xref target="status.codes"/>. To allow existing parsers to
645   properly handle them, new status codes cannot disallow a response body,
646   although they can mandate a zero-length response body. They can require the
647   presence of one or more particular HTTP response header(s).
648</t>
649<t>
650   Likewise, their definitions can specify that caches are allowed to use
651   heuristics to determine their freshness (see &caching;; by default, it is
652   not allowed), and can define how to determine the resource which they
653   carry a representation for (see <xref
654   target="identifying.response.associated.with.representation"/>; by default,
655   it is anonymous).
656</t>
657</section>
658
659</section>
660
661</section>
662
663<section title="Response Header Fields" anchor="response.header.fields">
664  <x:anchor-alias value="response-header"/>
665<t>
666   The response header fields allow the server to pass additional
667   information about the response which cannot be placed in the Status-Line.
668   These header fields give information about the server and about
669   further access to the target resource (&effective-request-uri;).
670</t>
671<texttable align="left">
672  <ttcol>Header Field Name</ttcol><ttcol>Defined in...</ttcol>
673
674  <c>Accept-Ranges</c> <c>&header-accept-ranges;</c>
675  <c>Age</c> <c>&header-age;</c>
676  <c>Allow</c> <c><xref target="header.allow"/></c>
677  <c>ETag</c> <c>&header-etag;</c>
678  <c>Location</c> <c><xref target="header.location"/></c>
679  <c>Proxy-Authenticate</c> <c>&header-proxy-authenticate;</c>
680  <c>Retry-After</c> <c><xref target="header.retry-after"/></c>
681  <c>Server</c> <c><xref target="header.server"/></c>
682  <c>Vary</c> <c>&header-vary;</c>
683  <c>WWW-Authenticate</c> <c>&header-www-authenticate;</c>
684</texttable>
685</section>
686
687<section title="Representation" anchor="representation">
688<t>
689   Request and Response messages &MAY; transfer a representation if not otherwise
690   restricted by the request method or response status code. A representation
691   consists of metadata (representation header fields) and data (representation
692   body).  When a complete or partial representation is enclosed in an HTTP message,
693   it is referred to as the payload of the message. HTTP representations
694   are defined in &payload;.
695</t>
696<t>
697   A representation body is only present in a message when a message-body is
698   present, as described in &message-body;. The representation body is obtained
699   from the message-body by decoding any Transfer-Encoding that might
700   have been applied to ensure safe and proper transfer of the message.
701</t>
702
703<section title="Identifying the Resource Associated with a Representation" anchor="identifying.response.associated.with.representation">
704<t>
705   It is sometimes necessary to determine an identifier for the resource
706   associated with a representation.
707</t>
708<t>
709   An HTTP request representation, when present, is always associated with an
710   anonymous (i.e., unidentified) resource.
711</t>
712<t>
713   In the common case, an HTTP response is a representation of the target
714   resource (see &effective-request-uri;). However, this is not always the
715   case. To determine the URI of the resource a response is associated with,
716   the following rules are used (with the first applicable one being selected):
717</t>
718<t><list style="numbers">
719   <t>If the response status code is 200 or 203 and the request method was GET,
720   the response payload is a representation of the target resource.</t>
721   <t>If the response status code is 204, 206, or 304 and the request method was GET
722   or HEAD, the response payload is a partial representation of the target
723   resource (see &combining-responses;).</t>
724   <t>If the response has a Content-Location header field, and that URI is the same
725   as the effective request URI, the response payload is a representation of the
726   target resource.</t>
727   <t>If the response has a Content-Location header field, and that URI is not the
728   same as the effective request URI, then the response asserts that its
729   payload is a representation of the resource identified by the
730   Content-Location URI. However, such an assertion cannot be trusted unless
731   it can be verified by other means (not defined by HTTP).</t>
732   <t>Otherwise, the response is a representation of an anonymous (i.e.,
733   unidentified) resource.</t>
734</list></t>
735<t>
736  <cref anchor="TODO-req-uri">
737   The comparison function is going to have to be defined somewhere,
738   because we already need to compare URIs for things like cache invalidation.</cref>
739</t>
740</section>
741
742</section>
743
744
745<section title="Method Definitions" anchor="method.definitions">
746<t>
747   The set of common request methods for HTTP/1.1 is defined below. Although
748   this set can be expanded, additional methods cannot be assumed to
749   share the same semantics for separately extended clients and servers.
750</t>
751
752<section title="Safe and Idempotent Methods" anchor="safe.and.idempotent">
753
754<section title="Safe Methods" anchor="safe.methods">
755<iref item="Safe Methods" primary="true"/>
756<t>
757   Implementors need to be aware that the software represents the user in
758   their interactions over the Internet, and need to allow
759   the user to be aware of any actions they take which might have an
760   unexpected significance to themselves or others.
761</t>
762<t>
763   In particular, the convention has been established that the GET, HEAD,
764   OPTIONS, and TRACE request methods &SHOULD-NOT; have the significance
765   of taking an action other than retrieval. These request methods ought
766   to be considered "<x:dfn anchor="safe">safe</x:dfn>".
767   This allows user agents to represent other methods, such as POST, PUT
768   and DELETE, in a special way, so that the user is made aware of the
769   fact that a possibly unsafe action is being requested.
770</t>
771<t>
772   Naturally, it is not possible to ensure that the server does not
773   generate side-effects as a result of performing a GET request; in
774   fact, some dynamic resources consider that a feature. The important
775   distinction here is that the user did not request the side-effects,
776   so therefore cannot be held accountable for them.
777</t>
778</section>
779
780<section title="Idempotent Methods" anchor="idempotent.methods">
781<iref item="Idempotent Methods" primary="true"/>
782<t>
783   Request methods can also have the property of "idempotence" in that,
784   aside from error or expiration issues, the intended effect of multiple
785   identical requests is the same as for a single request.
786   PUT, DELETE, and all safe request methods are idempotent.
787   It is important to note that idempotence refers only to changes
788   requested by the client: a server is free to change its state due
789   to multiple requests for the purpose of tracking those requests,
790   versioning of results, etc.
791</t>
792</section>
793</section>
794
795<section title="OPTIONS" anchor="OPTIONS">
796  <rdf:Description>
797    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
798  </rdf:Description>
799  <iref primary="true" item="OPTIONS method" x:for-anchor=""/>
800  <iref primary="true" item="Methods" subitem="OPTIONS" x:for-anchor=""/>
801<t>
802   The OPTIONS method requests information about the
803   communication options available on the request/response chain
804   identified by the effective request URI. This method allows a client to
805   determine the options and/or requirements associated with a resource,
806   or the capabilities of a server, without implying a resource action
807   or initiating a resource retrieval.
808</t>
809<t>
810   Responses to the OPTIONS method are not cacheable.
811</t>
812<t>
813   If the OPTIONS request includes a message-body (as indicated by the
814   presence of Content-Length or Transfer-Encoding), then the media type
815   &MUST; be indicated by a Content-Type field. Although this
816   specification does not define any use for such a body, future
817   extensions to HTTP might use the OPTIONS body to make more detailed
818   queries on the server.
819</t>
820<t>
821   If the request-target is an asterisk ("*"), the OPTIONS request is
822   intended to apply to the server in general rather than to a specific
823   resource. Since a server's communication options typically depend on
824   the resource, the "*" request is only useful as a "ping" or "no-op"
825   type of method; it does nothing beyond allowing the client to test
826   the capabilities of the server. For example, this can be used to test
827   a proxy for HTTP/1.1 compliance (or lack thereof).
828</t>
829<t>
830   If the request-target is not an asterisk, the OPTIONS request applies
831   only to the options that are available when communicating with that
832   resource.
833</t>
834<t>
835   A 200 response &SHOULD; include any header fields that indicate
836   optional features implemented by the server and applicable to that
837   resource (e.g., Allow), possibly including extensions not defined by
838   this specification. The response body, if any, &SHOULD; also include
839   information about the communication options. The format for such a
840   body is not defined by this specification, but might be defined by
841   future extensions to HTTP. Content negotiation &MAY; be used to select
842   the appropriate response format. If no response body is included, the
843   response &MUST; include a Content-Length field with a field-value of
844   "0".
845</t>
846<t>
847   The Max-Forwards header field &MAY; be used to target a
848   specific proxy in the request chain (see <xref target="header.max-forwards"/>).
849   If no Max-Forwards field is present in the request, then the forwarded
850   request &MUST-NOT; include a Max-Forwards field.
851</t>
852</section>
853
854<section title="GET" anchor="GET">
855  <rdf:Description>
856    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
857  </rdf:Description>
858  <iref primary="true" item="GET method" x:for-anchor=""/>
859  <iref primary="true" item="Methods" subitem="GET" x:for-anchor=""/>
860<t>
861   The GET method requests transfer of a current representation of
862   the target resource.
863</t>
864<t>   
865   If the target resource is a data-producing process, it is the
866   produced data which shall be returned as the representation in the response and not
867   the source text of the process, unless that text happens to be the output of
868   the process.
869</t>
870<t>
871   The semantics of the GET method change to a "conditional GET" if the
872   request message includes an If-Modified-Since, If-Unmodified-Since,
873   If-Match, If-None-Match, or If-Range header field. A conditional GET
874   requests that the representation be transferred only under the
875   circumstances described by the conditional header field(s). The
876   conditional GET request is intended to reduce unnecessary network
877   usage by allowing cached representations to be refreshed without requiring
878   multiple requests or transferring data already held by the client.
879</t>
880<t>
881   The semantics of the GET method change to a "partial GET" if the
882   request message includes a Range header field. A partial GET requests
883   that only part of the representation be transferred, as described in &header-range;.
884   The partial GET request is intended to reduce unnecessary
885   network usage by allowing partially-retrieved representations to be
886   completed without transferring data already held by the client.
887</t>
888<t>
889   Bodies on GET requests have no defined semantics. Note that sending a body
890   on a GET request might cause some existing implementations to reject the
891   request.
892</t>
893<t>
894   The response to a GET request is cacheable and &MAY; be used to satisfy
895   subsequent GET and HEAD requests (see &caching;).
896</t>
897<t>
898   See <xref target="encoding.sensitive.information.in.uris"/> for security considerations when used for forms.
899</t>
900</section>
901
902<section title="HEAD" anchor="HEAD">
903  <rdf:Description>
904    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
905  </rdf:Description>
906  <iref primary="true" item="HEAD method" x:for-anchor=""/>
907  <iref primary="true" item="Methods" subitem="HEAD" x:for-anchor=""/>
908<t>
909   The HEAD method is identical to GET except that the server &MUST-NOT;
910   return a message-body in the response. The metadata contained
911   in the HTTP header fields in response to a HEAD request &SHOULD; be identical
912   to the information sent in response to a GET request. This method can
913   be used for obtaining metadata about the representation implied by the
914   request without transferring the representation body. This method is
915   often used for testing hypertext links for validity, accessibility,
916   and recent modification.
917</t>
918<t>
919   The response to a HEAD request is cacheable and &MAY; be used to satisfy
920   a subsequent HEAD request; see &caching;. It also &MAY; be used to update a previously cached
921   representation from that resource; if the new field values
922   indicate that the cached representation differs from the current representation (as
923   would be indicated by a change in Content-Length, Content-MD5, ETag
924   or Last-Modified), then the cache &MUST; treat the cache entry as
925   stale.
926</t>
927<t>
928   Bodies on HEAD requests have no defined semantics. Note that sending a body
929   on a HEAD request might cause some existing implementations to reject the
930   request.
931</t>
932</section>
933
934<section title="POST" anchor="POST">
935  <iref primary="true" item="POST method" x:for-anchor=""/>
936  <iref primary="true" item="Methods" subitem="POST" x:for-anchor=""/>
937<t>
938   The POST method requests that the origin server accept the
939   representation enclosed in the request as data to be processed by the
940   target resource. POST is designed to allow a uniform method to cover the
941   following functions:
942  <list style="symbols">
943    <t>
944      Annotation of existing resources;
945    </t>
946    <t>
947        Posting a message to a bulletin board, newsgroup, mailing list,
948        or similar group of articles;
949    </t>
950    <t>
951        Providing a block of data, such as the result of submitting a
952        form, to a data-handling process;
953    </t>
954    <t>
955        Extending a database through an append operation.
956    </t>
957  </list>
958</t>
959<t>
960   The actual function performed by the POST method is determined by the
961   server and is usually dependent on the effective request URI.
962</t>
963<t>
964   The action performed by the POST method might not result in a
965   resource that can be identified by a URI. In this case, either 200
966   (OK) or 204 (No Content) is the appropriate response status code,
967   depending on whether or not the response includes a representation that
968   describes the result.
969</t>
970<t>
971   If a resource has been created on the origin server, the response
972   &SHOULD; be 201 (Created) and contain a representation which describes the
973   status of the request and refers to the new resource, and a Location
974   header field (see <xref target="header.location"/>).
975</t>
976<t>
977   Responses to POST requests are only cacheable when they
978   include explicit freshness information (see &p6-explicit;). A
979   cached POST response with a Content-Location header field
980   (see &header-content-location;) whose value is the effective
981   Request URI &MAY; be used to satisfy subsequent GET and HEAD requests.
982</t>
983<t>
984   Note that POST caching is not widely implemented.
985   However, the 303 (See Other) response can be used to direct the
986   user agent to retrieve a cacheable resource.
987</t>
988</section>
989
990<section title="PUT" anchor="PUT">
991  <iref primary="true" item="PUT method" x:for-anchor=""/>
992  <iref primary="true" item="Methods" subitem="PUT" x:for-anchor=""/>
993<t>
994   The PUT method requests that the state of the target resource
995   be created or replaced with the state defined by the representation
996   enclosed in the request message payload.  A successful PUT of a given
997   representation would suggest that a subsequent GET on that same target
998   resource will result in an equivalent representation being returned in
999   a 200 (OK) response.  However, there is no guarantee that such a state
1000   change will be observable, since the target resource might be acted
1001   upon by other user agents in parallel, or might be subject to dynamic
1002   processing by the origin server, before any subsequent GET is received.
1003   A successful response only implies that the user agent's intent was
1004   achieved at the time of its processing by the origin server.
1005</t>
1006<t>   
1007   If the target resource does not have a current representation and
1008   the PUT successfully creates one, then the origin server &MUST; inform
1009   the user agent by sending a 201 (Created) response.  If the target
1010   resource does have a current representation and that representation is
1011   successfully modified in accordance with the state of the enclosed
1012   representation, then either a 200 (OK) or 204 (No Content) response
1013   &SHOULD; be sent to indicate successful completion of the request.
1014</t>
1015<t>
1016   Unrecognized header fields &SHOULD; be ignored (i.e., not saved
1017   as part of the resource state).
1018</t>
1019<t>
1020   An origin server &SHOULD; verify that the PUT representation is
1021   consistent with any constraints which the server has for the target
1022   resource that cannot or will not be changed by the PUT.  This is
1023   particularly important when the origin server uses internal
1024   configuration information related to the URI in order to set the
1025   values for representation metadata on GET responses.  When a PUT
1026   representation is inconsistent with the target resource, the origin
1027   server &SHOULD; either make them consistent, by transforming the
1028   representation or changing the resource configuration, or respond
1029   with an appropriate error message containing sufficient information
1030   to explain why the representation is unsuitable.  The 409 (Conflict)
1031   or 415 (Unsupported Media Type) status codes are suggested, with the
1032   latter being specific to constraints on Content-Type values.
1033</t>
1034<t>
1035   For example, if the target resource is configured to always have a
1036   Content-Type of "text/html" and the representation being PUT has a
1037   Content-Type of "image/jpeg", then the origin server &SHOULD; do one of:
1038   (a) reconfigure the target resource to reflect the new media type;
1039   (b) transform the PUT representation to a format consistent with that
1040   of the resource before saving it as the new resource state; or,
1041   (c) reject the request with a 415 response indicating that the target
1042   resource is limited to "text/html", perhaps including a link to a
1043   different resource that would be a suitable target for the new
1044   representation.
1045</t>
1046<t>
1047   HTTP does not define exactly how a PUT method affects the state
1048   of an origin server beyond what can be expressed by the intent of
1049   the user agent request and the semantics of the origin server response.
1050   It does not define what a resource might be, in any sense of that
1051   word, beyond the interface provided via HTTP.  It does not define
1052   how resource state is "stored", nor how such storage might change
1053   as a result of a change in resource state, nor how the origin server
1054   translates resource state into representations.  Generally speaking,
1055   all implementation details behind the resource interface are
1056   intentionally hidden by the server.
1057</t>
1058<t>
1059   The fundamental difference between the POST and PUT methods is
1060   highlighted by the different intent for the target resource.
1061   The target resource in a POST request is intended to handle the
1062   enclosed representation as a data-accepting process, such as for
1063   a gateway to some other protocol or a document that accepts annotations.
1064   In contrast, the target resource in a PUT request is intended to
1065   take the enclosed representation as a new or replacement value.
1066   Hence, the intent of PUT is idempotent and visible to intermediaries,
1067   even though the exact effect is only known by the origin server.
1068</t>
1069<t>
1070   Proper interpretation of a PUT request presumes that the user agent
1071   knows what target resource is desired.  A service that is intended
1072   to select a proper URI on behalf of the client, after receiving
1073   a state-changing request, &SHOULD; be implemented using the POST
1074   method rather than PUT.  If the origin server will not make the
1075   requested PUT state change to the target resource and instead
1076   wishes to have it applied to a different resource, such as when the
1077   resource has been moved to a different URI, then the origin server
1078   &MUST; send a 301 (Moved Permanently) response; the user agent &MAY;
1079   then make its own decision regarding whether or not to redirect the
1080   request.
1081</t>
1082<t>
1083   A PUT request applied to the target resource &MAY; have side-effects
1084   on other resources.  For example, an article might have a URI for
1085   identifying "the current version" (a resource) which is separate
1086   from the URIs identifying each particular version (different
1087   resources that at one point shared the same state as the current version
1088   resource).  A successful PUT request on "the current version" URI might
1089   therefore create a new version resource in addition to changing the
1090   state of the target resource, and might also cause links to be added
1091   between the related resources.
1092</t>
1093<t>
1094   An origin server &SHOULD; reject any PUT request that contains a
1095   Content-Range header field, since it might be misinterpreted as
1096   partial content (or might be partial content that is being mistakenly
1097   PUT as a full representation).  Partial content updates are
1098   possible by targeting a separately identified resource with state
1099   that overlaps a portion of the larger resource, or by using a
1100   different method that has been specifically defined for partial
1101   updates (for example, the PATCH method defined in
1102   <xref target="RFC5789"/>).
1103</t>
1104<t>
1105   Responses to the PUT method are not cacheable. If a PUT request passes
1106   through a cache that has one or more stored responses for the effective
1107   request URI, those stored responses will be invalidated (see
1108   &p6-invalid;).
1109</t>
1110</section>
1111
1112<section title="DELETE" anchor="DELETE">
1113  <iref primary="true" item="DELETE method" x:for-anchor=""/>
1114  <iref primary="true" item="Methods" subitem="DELETE" x:for-anchor=""/>
1115<t>
1116   The DELETE method requests that the origin server delete the target
1117   resource. This method &MAY; be overridden by
1118   human intervention (or other means) on the origin server. The client cannot
1119   be guaranteed that the operation has been carried out, even if the
1120   status code returned from the origin server indicates that the action
1121   has been completed successfully. However, the server &SHOULD-NOT; 
1122   indicate success unless, at the time the response is given, it
1123   intends to delete the resource or move it to an inaccessible
1124   location.
1125</t>
1126<t>
1127   A successful response &SHOULD; be 200 (OK) if the response includes an
1128   representation describing the status, 202 (Accepted) if the action has not
1129   yet been enacted, or 204 (No Content) if the action has been enacted
1130   but the response does not include a representation.
1131</t>
1132<t>
1133   Bodies on DELETE requests have no defined semantics. Note that sending a body
1134   on a DELETE request might cause some existing implementations to reject the
1135   request.
1136</t>
1137<t>
1138   Responses to the DELETE method are not cacheable. If a DELETE request
1139   passes through a cache that has one or more stored responses for the
1140   effective request URI, those stored responses will be invalidated (see
1141   &p6-invalid;).
1142</t>
1143</section>
1144
1145<section title="TRACE" anchor="TRACE">
1146  <rdf:Description>
1147    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
1148  </rdf:Description>
1149  <iref primary="true" item="TRACE method" x:for-anchor=""/>
1150  <iref primary="true" item="Methods" subitem="TRACE" x:for-anchor=""/>
1151<t>
1152   The TRACE method requests a remote, application-layer loop-back
1153   of the request message. The final recipient of the request
1154   &SHOULD; reflect the message received back to the client as the
1155   message-body of a 200 (OK) response. The final recipient is either the
1156   origin server or the first proxy to receive a Max-Forwards
1157   value of zero (0) in the request (see <xref target="header.max-forwards"/>).
1158   A TRACE request &MUST-NOT; include a message-body.
1159</t>
1160<t>
1161   TRACE allows the client to see what is being received at the other
1162   end of the request chain and use that data for testing or diagnostic
1163   information. The value of the Via header field (&header-via;) is of
1164   particular interest, since it acts as a trace of the request chain.
1165   Use of the Max-Forwards header field allows the client to limit the
1166   length of the request chain, which is useful for testing a chain of
1167   proxies forwarding messages in an infinite loop.
1168</t>
1169<t>
1170   If the request is valid, the response &SHOULD; have a Content-Type of
1171   "message/http" (see &media-type-message-http;) and contain a message-body
1172   that encloses a copy of the entire request message.
1173   Responses to the TRACE method are not cacheable.
1174</t>
1175</section>
1176
1177<section title="CONNECT" anchor="CONNECT">
1178  <iref primary="true" item="CONNECT method" x:for-anchor=""/>
1179  <iref primary="true" item="Methods" subitem="CONNECT" x:for-anchor=""/>
1180<t>
1181   The CONNECT method requests that the proxy establish a tunnel
1182   to the request-target and then restrict its behavior to blind
1183   forwarding of packets until the connection is closed.
1184</t>
1185<t>
1186   When using CONNECT, the request-target &MUST; use the authority form
1187   (&request-target;); i.e., the request-target consists of only the
1188   host name and port number of the tunnel destination, separated by a colon.
1189   For example,
1190</t>
1191<figure><artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
1192CONNECT server.example.com:80 HTTP/1.1
1193Host: server.example.com:80
1194
1195</artwork></figure>
1196<t>
1197   Other HTTP mechanisms can be used normally with the CONNECT method &mdash;
1198   except end-to-end protocol Upgrade requests, since the
1199   tunnel must be established first.
1200</t>
1201<t>
1202   For example, proxy authentication might be used to establish the
1203   authority to create a tunnel:
1204</t>
1205<figure><artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
1206CONNECT server.example.com:80 HTTP/1.1
1207Host: server.example.com:80
1208Proxy-Authorization: basic aGVsbG86d29ybGQ=
1209
1210</artwork></figure>
1211<t>
1212   Bodies on CONNECT requests have no defined semantics. Note that sending a body
1213   on a CONNECT request might cause some existing implementations to reject the
1214   request.
1215</t>
1216<t>
1217   Like any other pipelined HTTP/1.1 request, data to be tunnel may be
1218   sent immediately after the blank line. The usual caveats also apply:
1219   data may be discarded if the eventual response is negative, and the
1220   connection may be reset with no response if more than one TCP segment
1221   is outstanding.
1222</t>
1223
1224<section title="Establishing a Tunnel with CONNECT">
1225<t>
1226   Any successful (2xx) response to a CONNECT request indicates that the
1227   proxy has established a connection to the requested host and port,
1228   and has switched to tunneling the current connection to that server
1229   connection.
1230</t>
1231<t>
1232   It may be the case that the proxy itself can only reach the requested
1233   origin server through another proxy.  In this case, the first proxy
1234   &SHOULD; make a CONNECT request of that next proxy, requesting a tunnel
1235   to the authority.  A proxy &MUST-NOT; respond with any 2xx status code
1236   unless it has either a direct or tunnel connection established to the
1237   authority.
1238</t>
1239<t>
1240   An origin server which receives a CONNECT request for itself &MAY;
1241   respond with a 2xx status code to indicate that a connection is
1242   established.
1243</t>
1244<t>
1245   If at any point either one of the peers gets disconnected, any
1246   outstanding data that came from that peer will be passed to the other
1247   one, and after that also the other connection will be terminated by
1248   the proxy. If there is outstanding data to that peer undelivered,
1249   that data will be discarded.
1250</t>
1251
1252</section>
1253</section>
1254</section>
1255
1256
1257<section title="Status Code Definitions" anchor="status.codes">
1258<t>
1259   Each Status-Code is described below, including any metadata required
1260   in the response.
1261</t>
1262
1263<section title="Informational 1xx" anchor="status.1xx">
1264<t>
1265   This class of status code indicates a provisional response,
1266   consisting only of the Status-Line and optional header fields, and is
1267   terminated by an empty line. There are no required header fields for this
1268   class of status code. Since HTTP/1.0 did not define any 1xx status
1269   codes, servers &MUST-NOT; send a 1xx response to an HTTP/1.0 client
1270   except under experimental conditions.
1271</t>
1272<t>
1273   A client &MUST; be prepared to accept one or more 1xx status responses
1274   prior to a regular response, even if the client does not expect a 100
1275   (Continue) status message. Unexpected 1xx status responses &MAY; be
1276   ignored by a user agent.
1277</t>
1278<t>
1279   Proxies &MUST; forward 1xx responses, unless the connection between the
1280   proxy and its client has been closed, or unless the proxy itself
1281   requested the generation of the 1xx response. (For example, if a
1282   proxy adds a "Expect: 100-continue" field when it forwards a request,
1283   then it need not forward the corresponding 100 (Continue)
1284   response(s).)
1285</t>
1286
1287<section title="100 Continue" anchor="status.100">
1288  <iref primary="true" item="100 Continue (status code)" x:for-anchor=""/>
1289  <iref primary="true" item="Status Codes" subitem="100 Continue" x:for-anchor=""/>
1290<t>
1291   The client &SHOULD; continue with its request. This interim response is
1292   used to inform the client that the initial part of the request has
1293   been received and has not yet been rejected by the server. The client
1294   &SHOULD; continue by sending the remainder of the request or, if the
1295   request has already been completed, ignore this response. The server
1296   &MUST; send a final response after the request has been completed. See
1297   &use100; for detailed discussion of the use and handling of this
1298   status code.
1299</t>
1300</section>
1301
1302<section title="101 Switching Protocols" anchor="status.101">
1303  <iref primary="true" item="101 Switching Protocols (status code)" x:for-anchor=""/>
1304  <iref primary="true" item="Status Codes" subitem="101 Switching Protocols" x:for-anchor=""/>
1305<t>
1306   The server understands and is willing to comply with the client's
1307   request, via the Upgrade message header field (&header-upgrade;), for a
1308   change in the application protocol being used on this connection. The
1309   server will switch protocols to those defined by the response's
1310   Upgrade header field immediately after the empty line which
1311   terminates the 101 response.
1312</t>
1313<t>
1314   The protocol &SHOULD; be switched only when it is advantageous to do
1315   so. For example, switching to a newer version of HTTP is advantageous
1316   over older versions, and switching to a real-time, synchronous
1317   protocol might be advantageous when delivering resources that use
1318   such features.
1319</t>
1320</section>
1321</section>
1322
1323<section title="Successful 2xx" anchor="status.2xx">
1324<t>
1325   This class of status code indicates that the client's request was
1326   successfully received, understood, and accepted.
1327</t>
1328
1329<section title="200 OK" anchor="status.200">
1330  <iref primary="true" item="200 OK (status code)" x:for-anchor=""/>
1331  <iref primary="true" item="Status Codes" subitem="200 OK" x:for-anchor=""/>
1332<t>
1333   The request has succeeded. The payload returned with the response
1334   is dependent on the method used in the request, for example:
1335  <list style="hanging">
1336    <t hangText="GET">
1337      a representation of the target resource is sent in the response;
1338    </t>
1339    <t hangText="HEAD">
1340      the same representation as GET, except without the message-body;
1341    </t>
1342    <t hangText="POST">
1343      a representation describing or containing the result of the action;
1344    </t>
1345    <t hangText="TRACE">
1346      a representation containing the request message as received by the
1347      end server.
1348    </t>
1349  </list>
1350</t>
1351<t>
1352   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1353   freshness for 200 responses.
1354</t>
1355</section>
1356
1357<section title="201 Created" anchor="status.201">
1358  <iref primary="true" item="201 Created (status code)" x:for-anchor=""/>
1359  <iref primary="true" item="Status Codes" subitem="201 Created" x:for-anchor=""/>
1360<t>
1361   The request has been fulfilled and has resulted in a new resource being
1362   created. The newly created resource can be referenced by the URI(s)
1363   returned in the payload of the response, with the most specific URI
1364   for the resource given by a Location header field. The response
1365   &SHOULD; include a payload containing a list of resource
1366   characteristics and location(s) from which the user or user agent can
1367   choose the one most appropriate. The payload format is specified by
1368   the media type given in the Content-Type header field. The origin
1369   server &MUST; create the resource before returning the 201 status code.
1370   If the action cannot be carried out immediately, the server &SHOULD;
1371   respond with 202 (Accepted) response instead.
1372</t>
1373<t>
1374   A 201 response &MAY; contain an ETag response header field indicating
1375   the current value of the entity-tag for the representation of the resource
1376   just created (see &header-etag;).
1377</t>
1378</section>
1379
1380<section title="202 Accepted" anchor="status.202">
1381  <iref primary="true" item="202 Accepted (status code)" x:for-anchor=""/>
1382  <iref primary="true" item="Status Codes" subitem="202 Accepted" x:for-anchor=""/>
1383<t>
1384   The request has been accepted for processing, but the processing has
1385   not been completed.  The request might or might not eventually be
1386   acted upon, as it might be disallowed when processing actually takes
1387   place. There is no facility for re-sending a status code from an
1388   asynchronous operation such as this.
1389</t>
1390<t>
1391   The 202 response is intentionally non-committal. Its purpose is to
1392   allow a server to accept a request for some other process (perhaps a
1393   batch-oriented process that is only run once per day) without
1394   requiring that the user agent's connection to the server persist
1395   until the process is completed. The representation returned with this
1396   response &SHOULD; include an indication of the request's current status
1397   and either a pointer to a status monitor or some estimate of when the
1398   user can expect the request to be fulfilled.
1399</t>
1400</section>
1401
1402<section title="203 Non-Authoritative Information" anchor="status.203">
1403  <iref primary="true" item="203 Non-Authoritative Information (status code)" x:for-anchor=""/>
1404  <iref primary="true" item="Status Codes" subitem="203 Non-Authoritative Information" x:for-anchor=""/>
1405<t>
1406   The representation in the response has been transformed or otherwise
1407   modified by a transforming proxy (&intermediaries;).  Note that the
1408   behaviour of transforming intermediaries is controlled by the no-transform
1409   Cache-Control directive (&header-cache-control;).
1410</t>
1411<t>
1412   This status code is only appropriate when the response status code would
1413   have been 200 (OK) otherwise. When the status code before transformation
1414   would have been different, the 214 Transformation Applied warn-code
1415   (&header-warning;) is appropriate.
1416</t>
1417<t>
1418   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1419   freshness for 203 responses.
1420</t>
1421</section>
1422
1423<section title="204 No Content" anchor="status.204">
1424  <iref primary="true" item="204 No Content (status code)" x:for-anchor=""/>
1425  <iref primary="true" item="Status Codes" subitem="204 No Content" x:for-anchor=""/>
1426<t>
1427   The 204 (No Content) status code indicates that the server has
1428   successfully fulfilled the request and that there is no additional
1429   content to return in the response payload body.  Metadata in the
1430   response header fields refer to the target resource and its current
1431   representation after the requested action.
1432</t>
1433<t>
1434   For example, if a 204 status code is received in response to a PUT
1435   request and the response contains an ETag header field, then the PUT
1436   was successful and the ETag field-value contains the entity-tag for
1437   the new representation of that target resource.
1438</t>
1439<t>
1440   The 204 response allows a server to indicate that the action has been
1441   successfully applied to the target resource while implying that the
1442   user agent &SHOULD-NOT; traverse away from its current "document view"
1443   (if any).  The server assumes that the user agent will provide some
1444   indication of the success to its user, in accord with its own interface,
1445   and apply any new or updated metadata in the response to the active
1446   representation.
1447</t>
1448<t>
1449   For example, a 204 status code is commonly used with document editing
1450   interfaces corresponding to a "save" action, such that the document
1451   being saved remains available to the user for editing. It is also
1452   frequently used with interfaces that expect automated data transfers
1453   to be prevalent, such as within distributed version control systems.
1454</t>
1455<t>
1456   The 204 response &MUST-NOT; include a message-body, and thus is always
1457   terminated by the first empty line after the header fields.
1458</t>
1459</section>
1460
1461<section title="205 Reset Content" anchor="status.205">
1462  <iref primary="true" item="205 Reset Content (status code)" x:for-anchor=""/>
1463  <iref primary="true" item="Status Codes" subitem="205 Reset Content" x:for-anchor=""/>
1464<t>
1465   The server has fulfilled the request and the user agent &SHOULD; reset
1466   the document view which caused the request to be sent. This response
1467   is primarily intended to allow input for actions to take place via
1468   user input, followed by a clearing of the form in which the input is
1469   given so that the user can easily initiate another input action.
1470</t>
1471<t>   
1472   The message-body included with the response &MUST; be empty. Note that
1473   receivers still need to parse the response according to the algorithm defined
1474   in &message-body;.
1475</t>
1476</section>
1477
1478<section title="206 Partial Content" anchor="status.206">
1479  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
1480  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
1481  <rdf:Description>
1482    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1483  </rdf:Description>
1484<t>
1485   The server has fulfilled the partial GET request for the resource
1486   and the enclosed payload is a partial representation as defined in &status-206;.
1487</t>
1488<t>
1489   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1490   freshness for 206 responses.
1491</t>
1492</section>
1493</section>
1494
1495<section title="Redirection 3xx" anchor="status.3xx">
1496<t>
1497   This class of status code indicates that further action needs to be
1498   taken by the user agent in order to fulfill the request.  The action
1499   required &MAY; be carried out by the user agent without interaction
1500   with the user if and only if the method used in the second request is
1501   known to be "safe", as defined in <xref target="safe.methods"/>.
1502   A client &SHOULD; detect infinite redirection loops, since such loops
1503   generate network traffic for each redirection.
1504</t>
1505<x:note>
1506  <t>
1507    <x:h>Note:</x:h> An earlier version of this specification recommended a
1508    maximum of five redirections (<xref target="RFC2068" x:fmt="," x:sec="10.3"/>).
1509    Content developers need to be aware that some clients might
1510    implement such a fixed limitation.
1511  </t>
1512</x:note>
1513
1514<section title="300 Multiple Choices" anchor="status.300">
1515  <iref primary="true" item="300 Multiple Choices (status code)" x:for-anchor=""/>
1516  <iref primary="true" item="Status Codes" subitem="300 Multiple Choices" x:for-anchor=""/>
1517<t>
1518   The target resource has more than one
1519   representation, each with its own specific location, and agent-driven
1520   negotiation information (&content-negotiation;) is being provided so that
1521   the user (or user agent) can select a preferred representation by
1522   redirecting its request to that location.
1523</t>
1524<t>
1525   Unless it was a HEAD request, the response &SHOULD; include a representation
1526   containing a list of representation metadata and location(s) from
1527   which the user or user agent can choose the one most appropriate. The
1528   data format is specified by the media type given in the Content-Type
1529   header field. Depending upon the format and the capabilities of
1530   the user agent, selection of the most appropriate choice &MAY; be
1531   performed automatically. However, this specification does not define
1532   any standard for such automatic selection.
1533</t>
1534<t>
1535   If the server has a preferred choice of representation, it &SHOULD;
1536   include the specific URI for that representation in the Location
1537   field; user agents &MAY; use the Location field value for automatic
1538   redirection.
1539</t>
1540<t>
1541   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1542   freshness for 300 responses.
1543</t>
1544
1545</section>
1546
1547<section title="301 Moved Permanently" anchor="status.301">
1548  <iref primary="true" item="301 Moved Permanently (status code)" x:for-anchor=""/>
1549  <iref primary="true" item="Status Codes" subitem="301 Moved Permanently" x:for-anchor=""/>
1550<t>
1551   The target resource has been assigned a new permanent URI and any
1552   future references to this resource &SHOULD; use one of the returned
1553   URIs.  Clients with link editing capabilities ought to automatically
1554   re-link references to the effective request URI to one or more of the new
1555   references returned by the server, where possible.
1556</t>
1557<t>
1558   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1559   freshness for 301 responses.
1560</t>
1561<t>
1562   The new permanent URI &SHOULD; be given by the Location field in the
1563   response. Unless the request method was HEAD, the representation of the
1564   response &SHOULD; contain a short hypertext note with a hyperlink to
1565   the new URI(s).
1566</t>
1567<t>
1568   If the 301 status code is received in response to a request method
1569   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1570   then the request &MAY; be automatically redirected by the user agent without
1571   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1572   request unless it can be confirmed by the user, since this might
1573   change the conditions under which the request was issued.
1574</t>
1575<x:note>
1576  <t>
1577    <x:h>Note:</x:h> When automatically redirecting a POST request after
1578    receiving a 301 status code, some existing HTTP/1.0 user agents
1579    will erroneously change it into a GET request.
1580  </t>
1581</x:note>
1582</section>
1583
1584<section title="302 Found" anchor="status.302">
1585  <iref primary="true" item="302 Found (status code)" x:for-anchor=""/>
1586  <iref primary="true" item="Status Codes" subitem="302 Found" x:for-anchor=""/>
1587<t>
1588   The target resource resides temporarily under a different URI.
1589   Since the redirection might be altered on occasion, the client &SHOULD;
1590   continue to use the effective request URI for future requests.
1591</t>
1592<t>
1593   The temporary URI &SHOULD; be given by the Location field in the
1594   response. Unless the request method was HEAD, the representation of the
1595   response &SHOULD; contain a short hypertext note with a hyperlink to
1596   the new URI(s).
1597</t>
1598<t>
1599   If the 302 status code is received in response to a request method
1600   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1601   then the request &MAY; be automatically redirected by the user agent without
1602   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1603   request unless it can be confirmed by the user, since this might
1604   change the conditions under which the request was issued.
1605</t>
1606<x:note>
1607  <t>
1608    <x:h>Note:</x:h> HTTP/1.0 (<xref target="RFC1945" x:fmt="," x:sec="9.3"/>)
1609    and the first version of HTTP/1.1 (<xref target="RFC2068" x:fmt="," x:sec ="10.3.3"/>)
1610    specify that the client is not allowed to change the method on the
1611    redirected request.  However, most existing user agent implementations
1612    treat 302 as if it were a 303 response, performing a GET on the Location
1613    field-value regardless of the original request method. Therefore, a
1614    previous version of this specification
1615    (<xref target="RFC2616" x:fmt="," x:sec="10.3.3"/>) has added the
1616    status codes
1617    <xref target="status.303" format="none">303</xref> and
1618    <xref target="status.307" format="none">307</xref> for servers that wish
1619    to make unambiguously clear which kind of reaction is expected of the
1620    client.
1621  </t>
1622</x:note>
1623</section>
1624
1625<section title="303 See Other" anchor="status.303">
1626  <iref primary="true" item="303 See Other (status code)" x:for-anchor=""/>
1627  <iref primary="true" item="Status Codes" subitem="303 See Other" x:for-anchor=""/>
1628<t>
1629   The server directs the user agent to a different resource, indicated
1630   by a URI in the Location header field, that provides an indirect
1631   response to the original request.  The user agent &MAY; perform a GET
1632   request on the URI in the Location field in order to obtain a
1633   representation corresponding to the response, be redirected again,
1634   or end with an error status.  The Location URI is not a substitute
1635   reference for the effective request URI.
1636</t>
1637<t>
1638   The 303 status code is generally applicable to any HTTP method.  It is
1639   primarily used to allow the output of a POST action to redirect
1640   the user agent to a selected resource, since doing so provides the
1641   information corresponding to the POST response in a form that
1642   can be separately identified, bookmarked, and cached independent
1643   of the original request.
1644</t>
1645<t>
1646   A 303 response to a GET request indicates that the requested
1647   resource does not have a representation of its own that can be
1648   transferred by the server over HTTP.  The Location URI indicates a
1649   resource that is descriptive of the target resource, such that the
1650   follow-on representation might be useful to recipients without
1651   implying that it adequately represents the target resource.
1652   Note that answers to the questions of what can be represented, what
1653   representations are adequate, and what might be a useful description
1654   are outside the scope of HTTP and thus entirely determined by the
1655   URI owner(s).
1656</t>
1657<t>
1658   Except for responses to a HEAD request, the representation of a 303
1659   response &SHOULD; contain a short hypertext note with a hyperlink
1660   to the Location URI.
1661</t>
1662</section>
1663
1664<section title="304 Not Modified" anchor="status.304">
1665  <iref primary="true" item="304 Not Modified (status code)" x:for-anchor=""/>
1666  <iref primary="true" item="Status Codes" subitem="304 Not Modified" x:for-anchor=""/>
1667  <rdf:Description>
1668    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1669  </rdf:Description>
1670<t>
1671   The response to the request has not been modified since the conditions
1672   indicated by the client's conditional GET request, as defined in &status-304;.
1673</t>
1674</section>
1675
1676<section title="305 Use Proxy" anchor="status.305">
1677  <iref primary="true" item="305 Use Proxy (status code)" x:for-anchor=""/>
1678  <iref primary="true" item="Status Codes" subitem="305 Use Proxy" x:for-anchor=""/>
1679<t>
1680   The 305 status code was defined in a previous version of this specification
1681   (see <xref target="changes.from.rfc.2616"/>), and is now deprecated.
1682</t>
1683</section>
1684
1685<section title="306 (Unused)" anchor="status.306">
1686  <iref primary="true" item="306 (Unused) (status code)" x:for-anchor=""/>
1687  <iref primary="true" item="Status Codes" subitem="306 (Unused)" x:for-anchor=""/>
1688<t>
1689   The 306 status code was used in a previous version of the
1690   specification, is no longer used, and the code is reserved.
1691</t>
1692</section>
1693
1694<section title="307 Temporary Redirect" anchor="status.307">
1695  <iref primary="true" item="307 Temporary Redirect (status code)" x:for-anchor=""/>
1696  <iref primary="true" item="Status Codes" subitem="307 Temporary Redirect" x:for-anchor=""/>
1697<t>
1698   The target resource resides temporarily under a different URI.
1699   Since the redirection can change over time, the client &SHOULD;
1700   continue to use the effective request URI for future requests.
1701</t>
1702<t>
1703   The temporary URI &SHOULD; be given by the Location field in the
1704   response. Unless the request method was HEAD, the representation of the
1705   response &SHOULD; contain a short hypertext note with a hyperlink to
1706   the new URI(s), since many pre-HTTP/1.1 user agents do not
1707   understand the 307 status code. Therefore, the note &SHOULD; contain the
1708   information necessary for a user to repeat the original request on
1709   the new URI.
1710</t>
1711<t>
1712   If the 307 status code is received in response to a request method
1713   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1714   then the request &MAY; be automatically redirected by the user agent without
1715   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1716   request unless it can be confirmed by the user, since this might
1717   change the conditions under which the request was issued.
1718</t>
1719</section>
1720</section>
1721
1722<section title="Client Error 4xx" anchor="status.4xx">
1723<t>
1724   The 4xx class of status code is intended for cases in which the
1725   client seems to have erred. Except when responding to a HEAD request,
1726   the server &SHOULD; include a representation containing an explanation of the
1727   error situation, and whether it is a temporary or permanent
1728   condition. These status codes are applicable to any request method.
1729   User agents &SHOULD; display any included representation to the user.
1730</t>
1731<t>
1732   If the client is sending data, a server implementation using TCP
1733   &SHOULD; be careful to ensure that the client acknowledges receipt of
1734   the packet(s) containing the response, before the server closes the
1735   input connection. If the client continues sending data to the server
1736   after the close, the server's TCP stack will send a reset packet to
1737   the client, which might erase the client's unacknowledged input buffers
1738   before they can be read and interpreted by the HTTP application.
1739</t>
1740
1741<section title="400 Bad Request" anchor="status.400">
1742  <iref primary="true" item="400 Bad Request (status code)" x:for-anchor=""/>
1743  <iref primary="true" item="Status Codes" subitem="400 Bad Request" x:for-anchor=""/>
1744<t>
1745   The request could not be understood by the server due to malformed
1746   syntax. The client &SHOULD-NOT; repeat the request without
1747   modifications.
1748</t>
1749</section>
1750
1751<section title="401 Unauthorized" anchor="status.401">
1752  <iref primary="true" item="401 Unauthorized (status code)" x:for-anchor=""/>
1753  <iref primary="true" item="Status Codes" subitem="401 Unauthorized" x:for-anchor=""/>
1754  <rdf:Description>
1755    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part7</redirects-to>
1756  </rdf:Description>
1757<t>
1758   The request requires user authentication (see &status-401;).
1759</t>
1760</section>
1761
1762<section title="402 Payment Required" anchor="status.402">
1763  <iref primary="true" item="402 Payment Required (status code)" x:for-anchor=""/>
1764  <iref primary="true" item="Status Codes" subitem="402 Payment Required" x:for-anchor=""/>
1765<t>
1766   This code is reserved for future use.
1767</t>
1768</section>
1769
1770<section title="403 Forbidden" anchor="status.403">
1771  <iref primary="true" item="403 Forbidden (status code)" x:for-anchor=""/>
1772  <iref primary="true" item="Status Codes" subitem="403 Forbidden" x:for-anchor=""/>
1773<t>
1774   The server understood the request, but refuses to authorize it. Providing
1775   different user authentication credentials might be successful, but any
1776   credentials that were provided in the request are insufficient. The request
1777   &SHOULD-NOT; be repeated with the same credentials.
1778</t>
1779<t>
1780   If the request method was not HEAD and the server wishes to make
1781   public why the request has not been fulfilled, it &SHOULD; describe the
1782   reason for the refusal in the representation.  If the server does not wish to
1783   make this information available to the client, the status code 404
1784   (Not Found) &MAY; be used instead.
1785</t>
1786</section>
1787
1788<section title="404 Not Found" anchor="status.404">
1789  <iref primary="true" item="404 Not Found (status code)" x:for-anchor=""/>
1790  <iref primary="true" item="Status Codes" subitem="404 Not Found" x:for-anchor=""/>
1791<t>
1792   The server has not found anything matching the effective request URI. No
1793   indication is given of whether the condition is temporary or
1794   permanent. The 410 (Gone) status code &SHOULD; be used if the server
1795   knows, through some internally configurable mechanism, that an old
1796   resource is permanently unavailable and has no forwarding address.
1797   This status code is commonly used when the server does not wish to
1798   reveal exactly why the request has been refused, or when no other
1799   response is applicable.
1800</t>
1801</section>
1802
1803<section title="405 Method Not Allowed" anchor="status.405">
1804  <iref primary="true" item="405 Method Not Allowed (status code)" x:for-anchor=""/>
1805  <iref primary="true" item="Status Codes" subitem="405 Method Not Allowed" x:for-anchor=""/>
1806<t>
1807   The method specified in the Request-Line is not allowed for the target
1808   resource. The response &MUST; include an Allow header field containing a
1809   list of valid methods for the requested resource.
1810</t>
1811</section>
1812
1813<section title="406 Not Acceptable" anchor="status.406">
1814  <iref primary="true" item="406 Not Acceptable (status code)" x:for-anchor=""/>
1815  <iref primary="true" item="Status Codes" subitem="406 Not Acceptable" x:for-anchor=""/>
1816<t>
1817   The resource identified by the request is only capable of generating
1818   response representations which have content characteristics not acceptable
1819   according to the accept header fields sent in the request.
1820</t>
1821<t>
1822   Unless it was a HEAD request, the response &SHOULD; include a representation
1823   containing a list of available representation characteristics and location(s)
1824   from which the user or user agent can choose the one most
1825   appropriate. The data format is specified by the media type given
1826   in the Content-Type header field. Depending upon the format and the
1827   capabilities of the user agent, selection of the most appropriate
1828   choice &MAY; be performed automatically. However, this specification
1829   does not define any standard for such automatic selection.
1830</t>
1831<x:note>
1832  <t>
1833    <x:h>Note:</x:h> HTTP/1.1 servers are allowed to return responses which are
1834    not acceptable according to the accept header fields sent in the
1835    request. In some cases, this might even be preferable to sending a
1836    406 response. User agents are encouraged to inspect the header fields of
1837    an incoming response to determine if it is acceptable.
1838  </t>
1839</x:note>
1840<t>
1841   If the response could be unacceptable, a user agent &SHOULD;
1842   temporarily stop receipt of more data and query the user for a
1843   decision on further actions.
1844</t>
1845</section>
1846
1847<section title="407 Proxy Authentication Required" anchor="status.407">
1848  <iref primary="true" item="407 Proxy Authentication Required (status code)" x:for-anchor=""/>
1849  <iref primary="true" item="Status Codes" subitem="407 Proxy Authentication Required" x:for-anchor=""/>
1850<t>
1851   This code is similar to 401 (Unauthorized), but indicates that the
1852   client must first authenticate itself with the proxy (see &status-407;).
1853</t>
1854</section>
1855
1856<section title="408 Request Timeout" anchor="status.408">
1857  <iref primary="true" item="408 Request Timeout (status code)" x:for-anchor=""/>
1858  <iref primary="true" item="Status Codes" subitem="408 Request Timeout" x:for-anchor=""/>
1859<t>
1860   The client did not produce a request within the time that the server
1861   was prepared to wait. The client &MAY; repeat the request without
1862   modifications at any later time.
1863</t>
1864</section>
1865
1866<section title="409 Conflict" anchor="status.409">
1867  <iref primary="true" item="409 Conflict (status code)" x:for-anchor=""/>
1868  <iref primary="true" item="Status Codes" subitem="409 Conflict" x:for-anchor=""/>
1869<t>
1870   The request could not be completed due to a conflict with the current
1871   state of the resource. This code is only allowed in situations where
1872   it is expected that the user might be able to resolve the conflict
1873   and resubmit the request. The response body &SHOULD; include enough
1874   information for the user to recognize the source of the conflict.
1875   Ideally, the response representation would include enough information for the
1876   user or user agent to fix the problem; however, that might not be
1877   possible and is not required.
1878</t>
1879<t>
1880   Conflicts are most likely to occur in response to a PUT request. For
1881   example, if versioning were being used and the representation being PUT
1882   included changes to a resource which conflict with those made by an
1883   earlier (third-party) request, the server might use the 409 response
1884   to indicate that it can't complete the request. In this case, the
1885   response representation would likely contain a list of the differences
1886   between the two versions in a format defined by the response
1887   Content-Type.
1888</t>
1889</section>
1890
1891<section title="410 Gone" anchor="status.410">
1892  <iref primary="true" item="410 Gone (status code)" x:for-anchor=""/>
1893  <iref primary="true" item="Status Codes" subitem="410 Gone" x:for-anchor=""/>
1894<t>
1895   The target resource is no longer available at the server and no
1896   forwarding address is known. This condition is expected to be
1897   considered permanent. Clients with link editing capabilities &SHOULD;
1898   delete references to the effective request URI after user approval. If the
1899   server does not know, or has no facility to determine, whether or not
1900   the condition is permanent, the status code 404 (Not Found) &SHOULD; be
1901   used instead.
1902</t>
1903<t>
1904   The 410 response is primarily intended to assist the task of web
1905   maintenance by notifying the recipient that the resource is
1906   intentionally unavailable and that the server owners desire that
1907   remote links to that resource be removed. Such an event is common for
1908   limited-time, promotional services and for resources belonging to
1909   individuals no longer working at the server's site. It is not
1910   necessary to mark all permanently unavailable resources as "gone" or
1911   to keep the mark for any length of time &mdash; that is left to the
1912   discretion of the server owner.
1913</t>
1914<t>
1915   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine freshness
1916   for 410 responses.
1917</t>
1918
1919</section>
1920
1921<section title="411 Length Required" anchor="status.411">
1922  <iref primary="true" item="411 Length Required (status code)" x:for-anchor=""/>
1923  <iref primary="true" item="Status Codes" subitem="411 Length Required" x:for-anchor=""/>
1924<t>
1925   The server refuses to accept the request without a defined Content-Length.
1926   The client &MAY; repeat the request if it adds a valid
1927   Content-Length header field containing the length of the message-body
1928   in the request message.
1929</t>
1930</section>
1931
1932<section title="412 Precondition Failed" anchor="status.412">
1933  <iref primary="true" item="412 Precondition Failed (status code)" x:for-anchor=""/>
1934  <iref primary="true" item="Status Codes" subitem="412 Precondition Failed" x:for-anchor=""/>
1935  <rdf:Description>
1936    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1937  </rdf:Description>
1938<t>
1939   The precondition given in one or more of the header fields
1940   evaluated to false when it was tested on the server, as defined in
1941   &status-412;.
1942</t>
1943</section>
1944
1945<section title="413 Request Entity Too Large" anchor="status.413">
1946  <iref primary="true" item="413 Request Entity Too Large (status code)" x:for-anchor=""/>
1947  <iref primary="true" item="Status Codes" subitem="413 Request Entity Too Large" x:for-anchor=""/>
1948<t>
1949   The server is refusing to process a request because the request
1950   representation is larger than the server is willing or able to process. The
1951   server &MAY; close the connection to prevent the client from continuing
1952   the request.
1953</t>
1954<t>
1955   If the condition is temporary, the server &SHOULD; include a Retry-After
1956   header field to indicate that it is temporary and after what
1957   time the client &MAY; try again.
1958</t>
1959</section>
1960
1961<section title="414 URI Too Long" anchor="status.414">
1962  <iref primary="true" item="414 URI Too Long (status code)" x:for-anchor=""/>
1963  <iref primary="true" item="Status Codes" subitem="414 URI Too Long" x:for-anchor=""/>
1964<t>
1965   The server is refusing to service the request because the effective request URI
1966   is longer than the server is willing to interpret. This rare
1967   condition is only likely to occur when a client has improperly
1968   converted a POST request to a GET request with long query
1969   information, when the client has descended into a URI "black hole" of
1970   redirection (e.g., a redirected URI prefix that points to a suffix of
1971   itself), or when the server is under attack by a client attempting to
1972   exploit security holes present in some servers using fixed-length
1973   buffers for reading or manipulating the effective request URI.
1974</t>
1975</section>
1976
1977<section title="415 Unsupported Media Type" anchor="status.415">
1978  <iref primary="true" item="415 Unsupported Media Type (status code)" x:for-anchor=""/>
1979  <iref primary="true" item="Status Codes" subitem="415 Unsupported Media Type" x:for-anchor=""/>
1980<t>
1981   The server is refusing to service the request because the request
1982   payload is in a format not supported by this request method on the
1983   target resource.
1984</t>
1985</section>
1986
1987<section title="416 Requested Range Not Satisfiable" anchor="status.416">
1988  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
1989  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
1990  <rdf:Description>
1991    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1992  </rdf:Description>
1993<t>
1994   The request included a Range header field (&header-range;) and none of
1995   the range-specifier values in this field overlap the current extent
1996   of the selected resource. See &status-416;.
1997</t>
1998</section>
1999
2000<section title="417 Expectation Failed" anchor="status.417">
2001  <iref primary="true" item="417 Expectation Failed (status code)" x:for-anchor=""/>
2002  <iref primary="true" item="Status Codes" subitem="417 Expectation Failed" x:for-anchor=""/>
2003<t>
2004   The expectation given in an Expect header field (see <xref target="header.expect"/>)
2005   could not be met by this server, or, if the server is a proxy,
2006   the server has unambiguous evidence that the request could not be met
2007   by the next-hop server.
2008</t>
2009</section>
2010
2011<section title="426 Upgrade Required" anchor="status.426">
2012  <iref primary="true" item="426 Upgrade Required (status code)" x:for-anchor=""/>
2013  <iref primary="true" item="Status Codes" subitem="426 Upgrade Required" x:for-anchor=""/>
2014<t>
2015   The request can not be completed without a prior protocol upgrade. This
2016   response &MUST; include an Upgrade header field (&header-upgrade;)
2017   specifying the required protocols.
2018</t>
2019<figure>
2020<preamble>Example:</preamble>
2021<artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
2022HTTP/1.1 426 Upgrade Required
2023Upgrade: HTTP/2.0
2024Connection: Upgrade
2025
2026</artwork></figure>
2027<t>
2028   The server &SHOULD; include a message body in the 426 response which
2029   indicates in human readable form the reason for the error and describes any
2030   alternative courses which may be available to the user.
2031</t>
2032</section>
2033</section>
2034
2035<section title="Server Error 5xx" anchor="status.5xx">
2036<t>
2037   Response status codes beginning with the digit "5" indicate cases in
2038   which the server is aware that it has erred or is incapable of
2039   performing the request. Except when responding to a HEAD request, the
2040   server &SHOULD; include a representation containing an explanation of the
2041   error situation, and whether it is a temporary or permanent
2042   condition. User agents &SHOULD; display any included representation to the
2043   user. These response codes are applicable to any request method.
2044</t>
2045
2046<section title="500 Internal Server Error" anchor="status.500">
2047  <iref primary="true" item="500 Internal Server Error (status code)" x:for-anchor=""/>
2048  <iref primary="true" item="Status Codes" subitem="500 Internal Server Error" x:for-anchor=""/>
2049<t>
2050   The server encountered an unexpected condition which prevented it
2051   from fulfilling the request.
2052</t>
2053</section>
2054
2055<section title="501 Not Implemented" anchor="status.501">
2056  <iref primary="true" item="501 Not Implemented (status code)" x:for-anchor=""/>
2057  <iref primary="true" item="Status Codes" subitem="501 Not Implemented" x:for-anchor=""/>
2058<t>
2059   The server does not support the functionality required to fulfill the
2060   request. This is the appropriate response when the server does not
2061   recognize the request method and is not capable of supporting it for
2062   any resource.
2063</t>
2064</section>
2065
2066<section title="502 Bad Gateway" anchor="status.502">
2067  <iref primary="true" item="502 Bad Gateway (status code)" x:for-anchor=""/>
2068  <iref primary="true" item="Status Codes" subitem="502 Bad Gateway" x:for-anchor=""/>
2069<t>
2070   The server, while acting as a gateway or proxy, received an invalid
2071   response from the upstream server it accessed in attempting to
2072   fulfill the request.
2073</t>
2074</section>
2075
2076<section title="503 Service Unavailable" anchor="status.503">
2077  <iref primary="true" item="503 Service Unavailable (status code)" x:for-anchor=""/>
2078  <iref primary="true" item="Status Codes" subitem="503 Service Unavailable" x:for-anchor=""/>
2079<t>
2080   The server is currently unable or unwilling to handle the request due to
2081   reasons such as temporary overloading, maintenance of the server, or rate
2082   limiting of the client.
2083</t>
2084<t>
2085   The implication is that this is a temporary condition which will be
2086   alleviated after some delay. If known, the length of the delay &MAY; be
2087   indicated in a Retry-After header field (<xref target="header.retry-after"/>).
2088   If no Retry-After is given, the client &SHOULD; handle the response as it
2089   would for a 500 response.
2090</t>
2091<x:note>
2092  <t>
2093    <x:h>Note:</x:h> The existence of the 503 status code does not imply that a
2094    server must use it when becoming overloaded. Some servers might wish
2095    to simply refuse the connection.
2096  </t>
2097</x:note>
2098</section>
2099
2100<section title="504 Gateway Timeout" anchor="status.504">
2101  <iref primary="true" item="504 Gateway Timeout (status code)" x:for-anchor=""/>
2102  <iref primary="true" item="Status Codes" subitem="504 Gateway Timeout" x:for-anchor=""/>
2103<t>
2104   The server, while acting as a gateway or proxy, did not receive a
2105   timely response from the upstream server specified by the URI (e.g.,
2106   HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed
2107   to access in attempting to complete the request.
2108</t>
2109<x:note>
2110  <t>
2111    <x:h>Note</x:h> to implementors: some deployed proxies are known to
2112    return 400 or 500 when DNS lookups time out.
2113  </t>
2114</x:note>
2115</section>
2116
2117<section title="505 HTTP Version Not Supported" anchor="status.505">
2118  <iref primary="true" item="505 HTTP Version Not Supported (status code)" x:for-anchor=""/>
2119  <iref primary="true" item="Status Codes" subitem="505 HTTP Version Not Supported" x:for-anchor=""/>
2120<t>
2121   The server does not support, or refuses to support, the protocol
2122   version that was used in the request message. The server is
2123   indicating that it is unable or unwilling to complete the request
2124   using the same major version as the client, as described in &http-version;,
2125   other than with this error message. The response &SHOULD; contain
2126   a representation describing why that version is not supported and what other
2127   protocols are supported by that server.
2128</t>
2129
2130</section>
2131</section>
2132</section>
2133
2134
2135<section title="Header Field Definitions" anchor="header.fields">
2136<t>
2137   This section defines the syntax and semantics of HTTP/1.1 header fields
2138   related to request and response semantics.
2139</t>
2140
2141<section title="Allow" anchor="header.allow">
2142  <iref primary="true" item="Allow header field" x:for-anchor=""/>
2143  <iref primary="true" item="Header Fields" subitem="Allow" x:for-anchor=""/>
2144  <x:anchor-alias value="Allow"/>
2145<t>
2146   The "Allow" header field lists the set of methods advertised as
2147   supported by the target resource. The purpose of this field is strictly to
2148   inform the recipient of valid request methods associated with the resource.
2149</t>
2150<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Allow"/>
2151  <x:ref>Allow</x:ref> = #<x:ref>Method</x:ref>
2152</artwork></figure>
2153<t>
2154   Example of use:
2155</t>
2156<figure><artwork type="example">
2157  Allow: GET, HEAD, PUT
2158</artwork></figure>
2159<t>
2160   The actual set of allowed methods is defined by the origin server at the
2161   time of each request.
2162</t>
2163<t>
2164   A proxy &MUST-NOT; modify the Allow header field &mdash; it does not need to
2165   understand all the methods specified in order to handle them according to
2166   the generic message handling rules.
2167</t>
2168</section>
2169
2170<section title="Expect" anchor="header.expect">
2171  <iref primary="true" item="Expect header field" x:for-anchor=""/>
2172  <iref primary="true" item="Header Fields" subitem="Expect" x:for-anchor=""/>
2173  <x:anchor-alias value="Expect"/>
2174  <x:anchor-alias value="expectation"/>
2175  <x:anchor-alias value="expectation-extension"/>
2176  <x:anchor-alias value="expect-params"/>
2177<t>
2178   The "Expect" header field is used to indicate that particular
2179   server behaviors are required by the client.
2180</t>
2181<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"/>
2182  <x:ref>Expect</x:ref>       = 1#<x:ref>expectation</x:ref>
2183 
2184  <x:ref>expectation</x:ref>  = "100-continue" / <x:ref>expectation-extension</x:ref>
2185  <x:ref>expectation-extension</x:ref> = <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> )
2186                           *<x:ref>expect-params</x:ref> ]
2187  <x:ref>expect-params</x:ref> = ";" <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> ) ]
2188</artwork></figure>
2189<t>
2190   A server that does not understand or is unable to comply with any of
2191   the expectation values in the Expect field of a request &MUST; respond
2192   with appropriate error status code. The server &MUST; respond with a 417
2193   (Expectation Failed) status code if any of the expectations cannot be met
2194   or, if there are other problems with the request, some other 4xx
2195   status code.
2196</t>
2197<t>
2198   This header field is defined with extensible syntax to allow for
2199   future extensions. If a server receives a request containing an
2200   Expect field that includes an expectation-extension that it does not
2201   support, it &MUST; respond with a 417 (Expectation Failed) status code.
2202</t>
2203<t>
2204   Comparison of expectation values is case-insensitive for unquoted
2205   tokens (including the 100-continue token), and is case-sensitive for
2206   quoted-string expectation-extensions.
2207</t>
2208<t>
2209   The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy &MUST;
2210   return a 417 (Expectation Failed) status code if it receives a request
2211   with an expectation that it cannot meet. However, the Expect
2212   header field itself is end-to-end; it &MUST; be forwarded if the
2213   request is forwarded.
2214</t>
2215<t>
2216   Many older HTTP/1.0 and HTTP/1.1 applications do not understand the
2217   Expect header field.
2218</t>
2219<t>
2220   See &use100; for the use of the 100 (Continue) status code.
2221</t>
2222</section>
2223
2224<section title="From" anchor="header.from">
2225  <iref primary="true" item="From header field" x:for-anchor=""/>
2226  <iref primary="true" item="Header Fields" subitem="From" x:for-anchor=""/>
2227  <x:anchor-alias value="From"/>
2228  <x:anchor-alias value="mailbox"/>
2229<t>
2230   The "From" header field, if given, &SHOULD; contain an Internet
2231   e-mail address for the human user who controls the requesting user
2232   agent. The address &SHOULD; be machine-usable, as defined by "mailbox"
2233   in <xref x:sec="3.4" x:fmt="of" target="RFC5322"/>:
2234</t>
2235<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="From"/>
2236  <x:ref>From</x:ref>    = <x:ref>mailbox</x:ref>
2237 
2238  <x:ref>mailbox</x:ref> = &lt;mailbox, defined in <xref x:sec="3.4" x:fmt="," target="RFC5322"/>&gt;
2239</artwork></figure>
2240<t>
2241   An example is:
2242</t>
2243<figure><artwork type="example">
2244  From: webmaster@example.org
2245</artwork></figure>
2246<t>
2247   This header field &MAY; be used for logging purposes and as a means for
2248   identifying the source of invalid or unwanted requests. It &SHOULD-NOT; 
2249   be used as an insecure form of access protection. The interpretation
2250   of this field is that the request is being performed on behalf of the
2251   person given, who accepts responsibility for the method performed. In
2252   particular, robot agents &SHOULD; include this header field so that the
2253   person responsible for running the robot can be contacted if problems
2254   occur on the receiving end.
2255</t>
2256<t>
2257   The Internet e-mail address in this field &MAY; be separate from the
2258   Internet host which issued the request. For example, when a request
2259   is passed through a proxy the original issuer's address &SHOULD; be
2260   used.
2261</t>
2262<t>
2263   The client &SHOULD-NOT;  send the From header field without the user's
2264   approval, as it might conflict with the user's privacy interests or
2265   their site's security policy. It is strongly recommended that the
2266   user be able to disable, enable, and modify the value of this field
2267   at any time prior to a request.
2268</t>
2269</section>
2270
2271<section title="Location" anchor="header.location">
2272  <iref primary="true" item="Location header field" x:for-anchor=""/>
2273  <iref primary="true" item="Header Fields" subitem="Location" x:for-anchor=""/>
2274  <x:anchor-alias value="Location"/>
2275<t>
2276   The "Location" header field is used to identify a newly created
2277   resource, or to redirect the recipient to a different location for
2278   completion of the request.
2279</t>
2280<t>
2281   For 201 (Created) responses, the Location is the URI of the new resource
2282   which was created by the request. For 3xx responses, the location &SHOULD;
2283   indicate the server's preferred URI for automatic redirection to the
2284   resource.
2285</t>
2286<t>
2287   The field value consists of a single URI-reference. When it has the form
2288   of a relative reference (<xref target="RFC3986" x:fmt="," x:sec="4.2"/>),
2289   the final value is computed by resolving it against the effective request
2290   URI (<xref target="RFC3986" x:fmt="," x:sec="5"/>).
2291</t>
2292<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Location"/>
2293  <x:ref>Location</x:ref> = <x:ref>URI-reference</x:ref>
2294</artwork></figure>
2295<figure>
2296<preamble>Examples are:</preamble><!--DO NOT DARE changing the vertical WSP below, it's necessary this way for xml2rfc-->
2297<artwork type="example">
2298  Location: http://www.example.org/pub/WWW/People.html#tim
2299</artwork></figure><figure><artwork type="example">  Location: /index.html
2300</artwork></figure>
2301<t>
2302   There are circumstances in which a fragment identifier in a Location URI
2303   would not be appropriate. For instance, when it appears in a 201 Created
2304   response, where the Location header field specifies the URI for the entire
2305   created resource.
2306</t>
2307<x:note>
2308  <t>
2309    <x:h>Note:</x:h> This specification does not define precedence rules
2310    for the case where the original URI, as navigated to by the user
2311    agent, and the Location header field value both contain fragment
2312    identifiers. Thus be aware that including fragment identifiers might
2313    inconvenience anyone relying on the semantics of the original URI's
2314    fragment identifier.
2315  </t>
2316</x:note>
2317<x:note>
2318  <t>
2319    <x:h>Note:</x:h> The Content-Location header field (&header-content-location;) differs
2320    from Location in that the Content-Location identifies the most specific
2321    resource corresponding to the enclosed representation.
2322    It is therefore possible for a response to contain header fields for
2323    both Location and Content-Location.
2324  </t>
2325</x:note>
2326</section>
2327
2328<section title="Max-Forwards" anchor="header.max-forwards">
2329  <iref primary="true" item="Max-Forwards header field" x:for-anchor=""/>
2330  <iref primary="true" item="Header Fields" subitem="Max-Forwards" x:for-anchor=""/>
2331  <x:anchor-alias value="Max-Forwards"/>
2332<t>
2333   The "Max-Forwards" header field provides a mechanism with the
2334   TRACE (<xref target="TRACE"/>) and OPTIONS (<xref target="OPTIONS"/>)
2335   methods to limit the number of times that the request is forwarded by
2336   proxies. This can be useful when the client is attempting to
2337   trace a request which appears to be failing or looping in mid-chain.
2338</t>
2339<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Max-Forwards"/>
2340  <x:ref>Max-Forwards</x:ref> = 1*<x:ref>DIGIT</x:ref>
2341</artwork></figure>
2342<t>
2343   The Max-Forwards value is a decimal integer indicating the remaining
2344   number of times this request message can be forwarded.
2345</t>
2346<t>
2347   Each recipient of a TRACE or OPTIONS request
2348   containing a Max-Forwards header field &MUST; check and update its
2349   value prior to forwarding the request. If the received value is zero
2350   (0), the recipient &MUST-NOT; forward the request; instead, it &MUST;
2351   respond as the final recipient. If the received Max-Forwards value is
2352   greater than zero, then the forwarded message &MUST; contain an updated
2353   Max-Forwards field with a value decremented by one (1).
2354</t>
2355<t>
2356   The Max-Forwards header field &MAY; be ignored for all other request
2357   methods.
2358</t>
2359</section>
2360
2361<section title="Referer" anchor="header.referer">
2362  <iref primary="true" item="Referer header field" x:for-anchor=""/>
2363  <iref primary="true" item="Header Fields" subitem="Referer" x:for-anchor=""/>
2364  <x:anchor-alias value="Referer"/>
2365<t>
2366   The "Referer" [sic] header field allows the client to specify the
2367   URI of the resource from which the effective request URI was obtained (the
2368   "referrer", although the header field is misspelled.).
2369</t>
2370<t>
2371   The Referer header field allows servers to generate lists of back-links to
2372   resources for interest, logging, optimized caching, etc. It also allows
2373   obsolete or mistyped links to be traced for maintenance. Some servers use
2374   Referer as a means of controlling where they allow links from (so-called
2375   "deep linking"), but legitimate requests do not always
2376   contain a Referer header field.
2377</t>
2378<t>
2379   If the effective request URI was obtained from a source that does not have its own
2380   URI (e.g., input from the user keyboard), the Referer field &MUST; either be
2381   sent with the value "about:blank", or not be sent at all. Note that this
2382   requirement does not apply to sources with non-HTTP URIs (e.g., FTP).
2383</t>
2384<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Referer"/>
2385  <x:ref>Referer</x:ref> = <x:ref>absolute-URI</x:ref> / <x:ref>partial-URI</x:ref>
2386</artwork></figure>
2387<t>
2388   Example:
2389</t>
2390<figure><artwork type="example">
2391  Referer: http://www.example.org/hypertext/Overview.html
2392</artwork></figure>
2393<t>
2394   If the field value is a relative URI, it &SHOULD; be interpreted
2395   relative to the effective request URI. The URI &MUST-NOT; include a fragment. See
2396   <xref target="encoding.sensitive.information.in.uris"/> for security considerations.
2397</t>
2398</section>
2399
2400<section title="Retry-After" anchor="header.retry-after">
2401  <iref primary="true" item="Retry-After header field" x:for-anchor=""/>
2402  <iref primary="true" item="Header Fields" subitem="Retry-After" x:for-anchor=""/>
2403  <x:anchor-alias value="Retry-After"/>
2404<t>
2405   The header "Retry-After" field can be used with a 503 (Service
2406   Unavailable) response to indicate how long the service is expected to
2407   be unavailable to the requesting client. This field &MAY; also be used
2408   with any 3xx (Redirection) response to indicate the minimum time the
2409   user-agent is asked wait before issuing the redirected request.
2410</t>
2411<t>
2412   The value of this field can be either an HTTP-date or an integer number
2413   of seconds (in decimal) after the time of the response.
2414</t>
2415<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Retry-After"/>
2416  <x:ref>Retry-After</x:ref> = <x:ref>HTTP-date</x:ref> / <x:ref>delta-seconds</x:ref>
2417</artwork></figure>
2418<t anchor="rule.delta-seconds">
2419  <x:anchor-alias value="delta-seconds"/>
2420   Time spans are non-negative decimal integers, representing time in
2421   seconds.
2422</t>
2423<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="delta-seconds"/>
2424  <x:ref>delta-seconds</x:ref>  = 1*<x:ref>DIGIT</x:ref>
2425</artwork></figure>
2426<t>
2427   Two examples of its use are
2428</t>
2429<figure><artwork type="example">
2430  Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
2431  Retry-After: 120
2432</artwork></figure>
2433<t>
2434   In the latter example, the delay is 2 minutes.
2435</t>
2436</section>
2437
2438<section title="Server" anchor="header.server">
2439  <iref primary="true" item="Server header field" x:for-anchor=""/>
2440  <iref primary="true" item="Header Fields" subitem="Server" x:for-anchor=""/>
2441  <x:anchor-alias value="Server"/>
2442<t>
2443   The "Server" header field contains information about the
2444   software used by the origin server to handle the request.
2445</t>
2446<t>
2447   The field can contain multiple product tokens (&product-tokens;) and
2448   comments (&header-fields;) identifying the server and any significant
2449   subproducts. The product tokens are listed in order of their significance
2450   for identifying the application.
2451</t>
2452<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Server"/>
2453  <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> ) )
2454</artwork></figure>
2455<t>
2456   Example:
2457</t>
2458<figure><artwork type="example">
2459  Server: CERN/3.0 libwww/2.17
2460</artwork></figure>
2461<t>
2462   If the response is being forwarded through a proxy, the proxy
2463   application &MUST-NOT; modify the Server header field. Instead, it
2464   &MUST; include a Via field (as described in &header-via;).
2465</t>
2466<x:note>
2467  <t>
2468    <x:h>Note:</x:h> Revealing the specific software version of the server might
2469    allow the server machine to become more vulnerable to attacks
2470    against software that is known to contain security holes. Server
2471    implementors are encouraged to make this field a configurable
2472    option.
2473  </t>
2474</x:note>
2475</section>
2476
2477<section title="User-Agent" anchor="header.user-agent">
2478  <iref primary="true" item="User-Agent header field" x:for-anchor=""/>
2479  <iref primary="true" item="Header Fields" subitem="User-Agent" x:for-anchor=""/>
2480  <x:anchor-alias value="User-Agent"/>
2481<t>
2482   The "User-Agent" header field contains information about the user
2483   agent originating the request. User agents &SHOULD; include this field with
2484   requests.
2485</t>
2486<t>
2487   Typically, it is used for statistical purposes, the tracing of protocol
2488   violations, and tailoring responses to avoid particular user agent
2489   limitations.
2490</t>
2491<t>
2492   The field can contain multiple product tokens (&product-tokens;)
2493   and comments (&header-fields;) identifying the agent and its
2494   significant subproducts. By convention, the product tokens are listed in
2495   order of their significance for identifying the application.
2496</t>
2497<t>
2498   Because this field is usually sent on every request a user agent makes,
2499   implementations are encouraged not to include needlessly fine-grained
2500   detail, and to limit (or even prohibit) the addition of subproducts by third
2501   parties. Overly long and detailed User-Agent field values make requests
2502   larger and can also be used to identify ("fingerprint") the user against
2503   their wishes.
2504</t>
2505<t>
2506   Likewise, implementations are encouraged not to use the product tokens of
2507   other implementations in order to declare compatibility with them, as this
2508   circumvents the purpose of the field. Finally, they are encouraged not to
2509   use comments to identify products; doing so makes the field value more
2510   difficult to parse.
2511</t>
2512<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="User-Agent"/>
2513  <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> ) )
2514</artwork></figure>
2515<t>
2516   Example:
2517</t>
2518<figure><artwork type="example">
2519  User-Agent: CERN-LineMode/2.15 libwww/2.17b3
2520</artwork></figure>
2521</section>
2522
2523</section>
2524
2525<section title="IANA Considerations" anchor="IANA.considerations">
2526
2527<section title="Method Registry" anchor="method.registration">
2528<t>
2529  The registration procedure for HTTP request methods is defined by
2530  <xref target="method.registry"/> of this document.
2531</t>
2532<t>
2533   The HTTP Method Registry shall be created at <eref target="http://www.iana.org/assignments/http-methods"/>
2534   and be populated with the registrations below:
2535</t>
2536<?BEGININC p2-semantics.iana-methods ?>
2537<!--AUTOGENERATED FROM extract-method-defs.xslt, do not edit manually-->
2538<texttable align="left" suppress-title="true" anchor="iana.method.registration.table">
2539   <ttcol>Method</ttcol>
2540   <ttcol>Safe</ttcol>
2541   <ttcol>Reference</ttcol>
2542   <c>CONNECT</c>
2543   <c>no</c>
2544   <c>
2545      <xref target="CONNECT"/>
2546   </c>
2547   <c>DELETE</c>
2548   <c>no</c>
2549   <c>
2550      <xref target="DELETE"/>
2551   </c>
2552   <c>GET</c>
2553   <c>yes</c>
2554   <c>
2555      <xref target="GET"/>
2556   </c>
2557   <c>HEAD</c>
2558   <c>yes</c>
2559   <c>
2560      <xref target="HEAD"/>
2561   </c>
2562   <c>OPTIONS</c>
2563   <c>yes</c>
2564   <c>
2565      <xref target="OPTIONS"/>
2566   </c>
2567   <c>POST</c>
2568   <c>no</c>
2569   <c>
2570      <xref target="POST"/>
2571   </c>
2572   <c>PUT</c>
2573   <c>no</c>
2574   <c>
2575      <xref target="PUT"/>
2576   </c>
2577   <c>TRACE</c>
2578   <c>yes</c>
2579   <c>
2580      <xref target="TRACE"/>
2581   </c>
2582</texttable>
2583<!--(END)-->
2584<?ENDINC p2-semantics.iana-methods ?>
2585</section>
2586
2587<section title="Status Code Registry" anchor="status.code.registration">
2588<t>
2589   The registration procedure for HTTP Status Codes &mdash; previously defined
2590   in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/> &mdash; is now defined
2591   by <xref target="status.code.registry"/> of this document.
2592</t>
2593<t>
2594   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
2595   shall be updated with the registrations below:
2596</t>
2597<?BEGININC p2-semantics.iana-status-codes ?>
2598<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
2599<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
2600   <ttcol>Value</ttcol>
2601   <ttcol>Description</ttcol>
2602   <ttcol>Reference</ttcol>
2603   <c>100</c>
2604   <c>Continue</c>
2605   <c>
2606      <xref target="status.100"/>
2607   </c>
2608   <c>101</c>
2609   <c>Switching Protocols</c>
2610   <c>
2611      <xref target="status.101"/>
2612   </c>
2613   <c>200</c>
2614   <c>OK</c>
2615   <c>
2616      <xref target="status.200"/>
2617   </c>
2618   <c>201</c>
2619   <c>Created</c>
2620   <c>
2621      <xref target="status.201"/>
2622   </c>
2623   <c>202</c>
2624   <c>Accepted</c>
2625   <c>
2626      <xref target="status.202"/>
2627   </c>
2628   <c>203</c>
2629   <c>Non-Authoritative Information</c>
2630   <c>
2631      <xref target="status.203"/>
2632   </c>
2633   <c>204</c>
2634   <c>No Content</c>
2635   <c>
2636      <xref target="status.204"/>
2637   </c>
2638   <c>205</c>
2639   <c>Reset Content</c>
2640   <c>
2641      <xref target="status.205"/>
2642   </c>
2643   <c>300</c>
2644   <c>Multiple Choices</c>
2645   <c>
2646      <xref target="status.300"/>
2647   </c>
2648   <c>301</c>
2649   <c>Moved Permanently</c>
2650   <c>
2651      <xref target="status.301"/>
2652   </c>
2653   <c>302</c>
2654   <c>Found</c>
2655   <c>
2656      <xref target="status.302"/>
2657   </c>
2658   <c>303</c>
2659   <c>See Other</c>
2660   <c>
2661      <xref target="status.303"/>
2662   </c>
2663   <c>305</c>
2664   <c>Use Proxy</c>
2665   <c>
2666      <xref target="status.305"/>
2667   </c>
2668   <c>306</c>
2669   <c>(Unused)</c>
2670   <c>
2671      <xref target="status.306"/>
2672   </c>
2673   <c>307</c>
2674   <c>Temporary Redirect</c>
2675   <c>
2676      <xref target="status.307"/>
2677   </c>
2678   <c>400</c>
2679   <c>Bad Request</c>
2680   <c>
2681      <xref target="status.400"/>
2682   </c>
2683   <c>402</c>
2684   <c>Payment Required</c>
2685   <c>
2686      <xref target="status.402"/>
2687   </c>
2688   <c>403</c>
2689   <c>Forbidden</c>
2690   <c>
2691      <xref target="status.403"/>
2692   </c>
2693   <c>404</c>
2694   <c>Not Found</c>
2695   <c>
2696      <xref target="status.404"/>
2697   </c>
2698   <c>405</c>
2699   <c>Method Not Allowed</c>
2700   <c>
2701      <xref target="status.405"/>
2702   </c>
2703   <c>406</c>
2704   <c>Not Acceptable</c>
2705   <c>
2706      <xref target="status.406"/>
2707   </c>
2708   <c>407</c>
2709   <c>Proxy Authentication Required</c>
2710   <c>
2711      <xref target="status.407"/>
2712   </c>
2713   <c>408</c>
2714   <c>Request Timeout</c>
2715   <c>
2716      <xref target="status.408"/>
2717   </c>
2718   <c>409</c>
2719   <c>Conflict</c>
2720   <c>
2721      <xref target="status.409"/>
2722   </c>
2723   <c>410</c>
2724   <c>Gone</c>
2725   <c>
2726      <xref target="status.410"/>
2727   </c>
2728   <c>411</c>
2729   <c>Length Required</c>
2730   <c>
2731      <xref target="status.411"/>
2732   </c>
2733   <c>413</c>
2734   <c>Request Entity Too Large</c>
2735   <c>
2736      <xref target="status.413"/>
2737   </c>
2738   <c>414</c>
2739   <c>URI Too Long</c>
2740   <c>
2741      <xref target="status.414"/>
2742   </c>
2743   <c>415</c>
2744   <c>Unsupported Media Type</c>
2745   <c>
2746      <xref target="status.415"/>
2747   </c>
2748   <c>417</c>
2749   <c>Expectation Failed</c>
2750   <c>
2751      <xref target="status.417"/>
2752   </c>
2753   <c>426</c>
2754   <c>Upgrade Required</c>
2755   <c>
2756      <xref target="status.426"/>
2757   </c>
2758   <c>500</c>
2759   <c>Internal Server Error</c>
2760   <c>
2761      <xref target="status.500"/>
2762   </c>
2763   <c>501</c>
2764   <c>Not Implemented</c>
2765   <c>
2766      <xref target="status.501"/>
2767   </c>
2768   <c>502</c>
2769   <c>Bad Gateway</c>
2770   <c>
2771      <xref target="status.502"/>
2772   </c>
2773   <c>503</c>
2774   <c>Service Unavailable</c>
2775   <c>
2776      <xref target="status.503"/>
2777   </c>
2778   <c>504</c>
2779   <c>Gateway Timeout</c>
2780   <c>
2781      <xref target="status.504"/>
2782   </c>
2783   <c>505</c>
2784   <c>HTTP Version Not Supported</c>
2785   <c>
2786      <xref target="status.505"/>
2787   </c>
2788</texttable>
2789<!--(END)-->
2790<?ENDINC p2-semantics.iana-status-codes ?>
2791</section>
2792<section title="Header Field Registration" anchor="header.field.registration">
2793<t>
2794   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> shall be updated
2795   with the permanent registrations below (see <xref target="RFC3864"/>):
2796</t>
2797<?BEGININC p2-semantics.iana-headers ?>
2798<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
2799<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
2800   <ttcol>Header Field Name</ttcol>
2801   <ttcol>Protocol</ttcol>
2802   <ttcol>Status</ttcol>
2803   <ttcol>Reference</ttcol>
2804
2805   <c>Allow</c>
2806   <c>http</c>
2807   <c>standard</c>
2808   <c>
2809      <xref target="header.allow"/>
2810   </c>
2811   <c>Expect</c>
2812   <c>http</c>
2813   <c>standard</c>
2814   <c>
2815      <xref target="header.expect"/>
2816   </c>
2817   <c>From</c>
2818   <c>http</c>
2819   <c>standard</c>
2820   <c>
2821      <xref target="header.from"/>
2822   </c>
2823   <c>Location</c>
2824   <c>http</c>
2825   <c>standard</c>
2826   <c>
2827      <xref target="header.location"/>
2828   </c>
2829   <c>Max-Forwards</c>
2830   <c>http</c>
2831   <c>standard</c>
2832   <c>
2833      <xref target="header.max-forwards"/>
2834   </c>
2835   <c>Referer</c>
2836   <c>http</c>
2837   <c>standard</c>
2838   <c>
2839      <xref target="header.referer"/>
2840   </c>
2841   <c>Retry-After</c>
2842   <c>http</c>
2843   <c>standard</c>
2844   <c>
2845      <xref target="header.retry-after"/>
2846   </c>
2847   <c>Server</c>
2848   <c>http</c>
2849   <c>standard</c>
2850   <c>
2851      <xref target="header.server"/>
2852   </c>
2853   <c>User-Agent</c>
2854   <c>http</c>
2855   <c>standard</c>
2856   <c>
2857      <xref target="header.user-agent"/>
2858   </c>
2859</texttable>
2860<!--(END)-->
2861<?ENDINC p2-semantics.iana-headers ?>
2862<t>
2863   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
2864</t>
2865</section>
2866</section>
2867
2868<section title="Security Considerations" anchor="security.considerations">
2869<t>
2870   This section is meant to inform application developers, information
2871   providers, and users of the security limitations in HTTP/1.1 as
2872   described by this document. The discussion does not include
2873   definitive solutions to the problems revealed, though it does make
2874   some suggestions for reducing security risks.
2875</t>
2876
2877<section title="Transfer of Sensitive Information" anchor="security.sensitive">
2878<t>
2879   Like any generic data transfer protocol, HTTP cannot regulate the
2880   content of the data that is transferred, nor is there any a priori
2881   method of determining the sensitivity of any particular piece of
2882   information within the context of any given request. Therefore,
2883   applications &SHOULD; supply as much control over this information as
2884   possible to the provider of that information. Four header fields are
2885   worth special mention in this context: Server, Via, Referer and From.
2886</t>
2887<t>
2888   Revealing the specific software version of the server might allow the
2889   server machine to become more vulnerable to attacks against software
2890   that is known to contain security holes. Implementors &SHOULD; make the
2891   Server header field a configurable option.
2892</t>
2893<t>
2894   Proxies which serve as a portal through a network firewall &SHOULD;
2895   take special precautions regarding the transfer of header information
2896   that identifies the hosts behind the firewall. In particular, they
2897   &SHOULD; remove, or replace with sanitized versions, any Via fields
2898   generated behind the firewall.
2899</t>
2900<t>
2901   The Referer header field allows reading patterns to be studied and reverse
2902   links drawn. Although it can be very useful, its power can be abused
2903   if user details are not separated from the information contained in
2904   the Referer. Even when the personal information has been removed, the
2905   Referer header field might indicate a private document's URI whose
2906   publication would be inappropriate.
2907</t>
2908<t>
2909   The information sent in the From field might conflict with the user's
2910   privacy interests or their site's security policy, and hence it
2911   &SHOULD-NOT;  be transmitted without the user being able to disable,
2912   enable, and modify the contents of the field. The user &MUST; be able
2913   to set the contents of this field within a user preference or
2914   application defaults configuration.
2915</t>
2916<t>
2917   We suggest, though do not require, that a convenient toggle interface
2918   be provided for the user to enable or disable the sending of From and
2919   Referer information.
2920</t>
2921<t>
2922   The User-Agent (<xref target="header.user-agent"/>) or Server (<xref
2923   target="header.server"/>) header fields can sometimes be used to determine
2924   that a specific client or server have a particular security hole which might
2925   be exploited. Unfortunately, this same information is often used for other
2926   valuable purposes for which HTTP currently has no better mechanism.
2927</t>
2928<t>
2929   Furthermore, the User-Agent header field may contain enough entropy to be
2930   used, possibly in conjunction with other material, to uniquely identify the
2931   user.
2932</t>
2933<t>
2934   Some request methods, like TRACE (<xref target="TRACE"/>), expose information
2935   that was sent in request header fields within the body of their response.
2936   Clients &SHOULD; be careful with sensitive information, like Cookies,
2937   Authorization credentials, and other header fields that might be used to
2938   collect data from the client.
2939</t> 
2940</section>
2941
2942<section title="Encoding Sensitive Information in URIs" anchor="encoding.sensitive.information.in.uris">
2943<t>
2944   Because the source of a link might be private information or might
2945   reveal an otherwise private information source, it is strongly
2946   recommended that the user be able to select whether or not the
2947   Referer field is sent. For example, a browser client could have a
2948   toggle switch for browsing openly/anonymously, which would
2949   respectively enable/disable the sending of Referer and From
2950   information.
2951</t>
2952<t>
2953   Clients &SHOULD-NOT; include a Referer header field in a (non-secure)
2954   HTTP request if the referring page was transferred with a secure
2955   protocol.
2956</t>
2957<t>
2958   Authors of services &SHOULD-NOT; use GET-based forms for the submission of
2959   sensitive data because that data will be placed in the request-target. Many
2960   existing servers, proxies, and user agents log or display the request-target
2961   in places where it might be visible to third parties. Such services can
2962   use POST-based form submission instead.
2963</t>
2964</section>
2965
2966<section title="Location Headers and Spoofing" anchor="location.spoofing">
2967<t>
2968   If a single server supports multiple organizations that do not trust
2969   one another, then it &MUST; check the values of Location and Content-Location
2970   header fields in responses that are generated under control of
2971   said organizations to make sure that they do not attempt to
2972   invalidate resources over which they have no authority.
2973</t>
2974</section>
2975
2976<section title="Security Considerations for CONNECT">
2977<t>
2978   Since tunneled data is opaque to the proxy, there are additional
2979   risks to tunneling to other well-known or reserved ports.
2980   A HTTP client CONNECTing to port 25 could relay spam
2981   via SMTP, for example. As such, proxies &SHOULD; restrict CONNECT
2982   access to a small number of known ports.
2983</t>
2984</section>
2985
2986</section>
2987
2988<section title="Acknowledgments" anchor="ack">
2989</section>
2990</middle>
2991<back>
2992
2993<references title="Normative References">
2994
2995<reference anchor="Part1">
2996  <front>
2997    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
2998    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2999      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3000      <address><email>fielding@gbiv.com</email></address>
3001    </author>
3002    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3003      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3004      <address><email>jg@freedesktop.org</email></address>
3005    </author>
3006    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3007      <organization abbrev="HP">Hewlett-Packard Company</organization>
3008      <address><email>JeffMogul@acm.org</email></address>
3009    </author>
3010    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3011      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3012      <address><email>henrikn@microsoft.com</email></address>
3013    </author>
3014    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3015      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3016      <address><email>LMM@acm.org</email></address>
3017    </author>
3018    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3019      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3020      <address><email>paulle@microsoft.com</email></address>
3021    </author>
3022    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3023      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3024      <address><email>timbl@w3.org</email></address>
3025    </author>
3026    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3027      <organization abbrev="W3C">World Wide Web Consortium</organization>
3028      <address><email>ylafon@w3.org</email></address>
3029    </author>
3030    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3031      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3032      <address><email>julian.reschke@greenbytes.de</email></address>
3033    </author>
3034    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3035  </front>
3036  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
3037  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
3038</reference>
3039
3040<reference anchor="Part3">
3041  <front>
3042    <title abbrev="HTTP/1.1">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
3043    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3044      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3045      <address><email>fielding@gbiv.com</email></address>
3046    </author>
3047    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3048      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3049      <address><email>jg@freedesktop.org</email></address>
3050    </author>
3051    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3052      <organization abbrev="HP">Hewlett-Packard Company</organization>
3053      <address><email>JeffMogul@acm.org</email></address>
3054    </author>
3055    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3056      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3057      <address><email>henrikn@microsoft.com</email></address>
3058    </author>
3059    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3060      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3061      <address><email>LMM@acm.org</email></address>
3062    </author>
3063    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3064      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3065      <address><email>paulle@microsoft.com</email></address>
3066    </author>
3067    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3068      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3069      <address><email>timbl@w3.org</email></address>
3070    </author>
3071    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3072      <organization abbrev="W3C">World Wide Web Consortium</organization>
3073      <address><email>ylafon@w3.org</email></address>
3074    </author>
3075    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3076      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3077      <address><email>julian.reschke@greenbytes.de</email></address>
3078    </author>
3079    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3080  </front>
3081  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p3-payload-&ID-VERSION;"/>
3082  <x:source href="p3-payload.xml" basename="p3-payload"/>
3083</reference>
3084
3085<reference anchor="Part4">
3086  <front>
3087    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
3088    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3089      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3090      <address><email>fielding@gbiv.com</email></address>
3091    </author>
3092    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3093      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3094      <address><email>jg@freedesktop.org</email></address>
3095    </author>
3096    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3097      <organization abbrev="HP">Hewlett-Packard Company</organization>
3098      <address><email>JeffMogul@acm.org</email></address>
3099    </author>
3100    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3101      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3102      <address><email>henrikn@microsoft.com</email></address>
3103    </author>
3104    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3105      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3106      <address><email>LMM@acm.org</email></address>
3107    </author>
3108    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3109      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3110      <address><email>paulle@microsoft.com</email></address>
3111    </author>
3112    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3113      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3114      <address><email>timbl@w3.org</email></address>
3115    </author>
3116    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3117      <organization abbrev="W3C">World Wide Web Consortium</organization>
3118      <address><email>ylafon@w3.org</email></address>
3119    </author>
3120    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3121      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3122      <address><email>julian.reschke@greenbytes.de</email></address>
3123    </author>
3124    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3125  </front>
3126  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
3127  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
3128</reference>
3129
3130<reference anchor="Part5">
3131  <front>
3132    <title abbrev="HTTP/1.1">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
3133    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3134      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3135      <address><email>fielding@gbiv.com</email></address>
3136    </author>
3137    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3138      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3139      <address><email>jg@freedesktop.org</email></address>
3140    </author>
3141    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3142      <organization abbrev="HP">Hewlett-Packard Company</organization>
3143      <address><email>JeffMogul@acm.org</email></address>
3144    </author>
3145    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3146      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3147      <address><email>henrikn@microsoft.com</email></address>
3148    </author>
3149    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3150      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3151      <address><email>LMM@acm.org</email></address>
3152    </author>
3153    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3154      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3155      <address><email>paulle@microsoft.com</email></address>
3156    </author>
3157    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3158      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3159      <address><email>timbl@w3.org</email></address>
3160    </author>
3161    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3162      <organization abbrev="W3C">World Wide Web Consortium</organization>
3163      <address><email>ylafon@w3.org</email></address>
3164    </author>
3165    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3166      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3167      <address><email>julian.reschke@greenbytes.de</email></address>
3168    </author>
3169    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3170  </front>
3171  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p5-range-&ID-VERSION;"/>
3172  <x:source href="p5-range.xml" basename="p5-range"/>
3173</reference>
3174
3175<reference anchor="Part6">
3176  <front>
3177    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
3178    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3179      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3180      <address><email>fielding@gbiv.com</email></address>
3181    </author>
3182    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3183      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3184      <address><email>jg@freedesktop.org</email></address>
3185    </author>
3186    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3187      <organization abbrev="HP">Hewlett-Packard Company</organization>
3188      <address><email>JeffMogul@acm.org</email></address>
3189    </author>
3190    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3191      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3192      <address><email>henrikn@microsoft.com</email></address>
3193    </author>
3194    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3195      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3196      <address><email>LMM@acm.org</email></address>
3197    </author>
3198    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3199      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3200      <address><email>paulle@microsoft.com</email></address>
3201    </author>
3202    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3203      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3204      <address><email>timbl@w3.org</email></address>
3205    </author>
3206    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3207      <organization abbrev="W3C">World Wide Web Consortium</organization>
3208      <address><email>ylafon@w3.org</email></address>
3209    </author>
3210    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
3211      <address><email>mnot@mnot.net</email></address>
3212    </author>
3213    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3214      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3215      <address><email>julian.reschke@greenbytes.de</email></address>
3216    </author>
3217    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3218  </front>
3219  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
3220  <x:source href="p6-cache.xml" basename="p6-cache"/>
3221</reference>
3222
3223<reference anchor="Part7">
3224  <front>
3225    <title abbrev="HTTP/1.1">HTTP/1.1, part 7: Authentication</title>
3226    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3227      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3228      <address><email>fielding@gbiv.com</email></address>
3229    </author>
3230    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3231      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3232      <address><email>jg@freedesktop.org</email></address>
3233    </author>
3234    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3235      <organization abbrev="HP">Hewlett-Packard Company</organization>
3236      <address><email>JeffMogul@acm.org</email></address>
3237    </author>
3238    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3239      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3240      <address><email>henrikn@microsoft.com</email></address>
3241    </author>
3242    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3243      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3244      <address><email>LMM@acm.org</email></address>
3245    </author>
3246    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3247      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3248      <address><email>paulle@microsoft.com</email></address>
3249    </author>
3250    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3251      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3252      <address><email>timbl@w3.org</email></address>
3253    </author>
3254    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3255      <organization abbrev="W3C">World Wide Web Consortium</organization>
3256      <address><email>ylafon@w3.org</email></address>
3257    </author>
3258    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3259      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3260      <address><email>julian.reschke@greenbytes.de</email></address>
3261    </author>
3262    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3263  </front>
3264  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p7-auth-&ID-VERSION;"/>
3265  <x:source href="p7-auth.xml" basename="p7-auth"/>
3266</reference>
3267
3268<reference anchor="RFC2119">
3269  <front>
3270    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
3271    <author initials="S." surname="Bradner" fullname="Scott Bradner">
3272      <organization>Harvard University</organization>
3273      <address><email>sob@harvard.edu</email></address>
3274    </author>
3275    <date month="March" year="1997"/>
3276  </front>
3277  <seriesInfo name="BCP" value="14"/>
3278  <seriesInfo name="RFC" value="2119"/>
3279</reference>
3280
3281<reference anchor="RFC3986">
3282 <front>
3283  <title abbrev='URI Generic Syntax'>Uniform Resource Identifier (URI): Generic Syntax</title>
3284  <author initials='T.' surname='Berners-Lee' fullname='Tim Berners-Lee'>
3285    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3286    <address>
3287       <email>timbl@w3.org</email>
3288       <uri>http://www.w3.org/People/Berners-Lee/</uri>
3289    </address>
3290  </author>
3291  <author initials='R.' surname='Fielding' fullname='Roy T. Fielding'>
3292    <organization abbrev="Day Software">Day Software</organization>
3293    <address>
3294      <email>fielding@gbiv.com</email>
3295      <uri>http://roy.gbiv.com/</uri>
3296    </address>
3297  </author>
3298  <author initials='L.' surname='Masinter' fullname='Larry Masinter'>
3299    <organization abbrev="Adobe Systems">Adobe Systems Incorporated</organization>
3300    <address>
3301      <email>LMM@acm.org</email>
3302      <uri>http://larry.masinter.net/</uri>
3303    </address>
3304  </author>
3305  <date month='January' year='2005'></date>
3306 </front>
3307 <seriesInfo name="STD" value="66"/>
3308 <seriesInfo name="RFC" value="3986"/>
3309</reference>
3310
3311<reference anchor="RFC5234">
3312  <front>
3313    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
3314    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
3315      <organization>Brandenburg InternetWorking</organization>
3316      <address>
3317        <email>dcrocker@bbiw.net</email>
3318      </address> 
3319    </author>
3320    <author initials="P." surname="Overell" fullname="Paul Overell">
3321      <organization>THUS plc.</organization>
3322      <address>
3323        <email>paul.overell@thus.net</email>
3324      </address>
3325    </author>
3326    <date month="January" year="2008"/>
3327  </front>
3328  <seriesInfo name="STD" value="68"/>
3329  <seriesInfo name="RFC" value="5234"/>
3330</reference>
3331
3332</references>
3333
3334<references title="Informative References">
3335
3336<reference anchor="RFC1945">
3337  <front>
3338    <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1.0</title>
3339    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3340      <organization>MIT, Laboratory for Computer Science</organization>
3341      <address><email>timbl@w3.org</email></address>
3342    </author>
3343    <author initials="R.T." surname="Fielding" fullname="Roy T. Fielding">
3344      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3345      <address><email>fielding@ics.uci.edu</email></address>
3346    </author>
3347    <author initials="H.F." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3348      <organization>W3 Consortium, MIT Laboratory for Computer Science</organization>
3349      <address><email>frystyk@w3.org</email></address>
3350    </author>
3351    <date month="May" year="1996"/>
3352  </front>
3353  <seriesInfo name="RFC" value="1945"/>
3354</reference>
3355
3356<reference anchor="RFC2068">
3357  <front>
3358    <title abbrev="HTTP/1.1">Hypertext Transfer Protocol -- HTTP/1.1</title>
3359    <author initials="R." surname="Fielding" fullname="Roy T. Fielding">
3360      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3361      <address><email>fielding@ics.uci.edu</email></address>
3362    </author>
3363    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3364      <organization>MIT Laboratory for Computer Science</organization>
3365      <address><email>jg@w3.org</email></address>
3366    </author>
3367    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3368      <organization>Digital Equipment Corporation, Western Research Laboratory</organization>
3369      <address><email>mogul@wrl.dec.com</email></address>
3370    </author>
3371    <author initials="H." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3372      <organization>MIT Laboratory for Computer Science</organization>
3373      <address><email>frystyk@w3.org</email></address>
3374    </author>
3375    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3376      <organization>MIT Laboratory for Computer Science</organization>
3377      <address><email>timbl@w3.org</email></address>
3378    </author>
3379    <date month="January" year="1997"/>
3380  </front>
3381  <seriesInfo name="RFC" value="2068"/>
3382</reference>
3383
3384<reference anchor="RFC2616">
3385  <front>
3386    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
3387    <author initials="R." surname="Fielding" fullname="R. Fielding">
3388      <organization>University of California, Irvine</organization>
3389      <address><email>fielding@ics.uci.edu</email></address>
3390    </author>
3391    <author initials="J." surname="Gettys" fullname="J. Gettys">
3392      <organization>W3C</organization>
3393      <address><email>jg@w3.org</email></address>
3394    </author>
3395    <author initials="J." surname="Mogul" fullname="J. Mogul">
3396      <organization>Compaq Computer Corporation</organization>
3397      <address><email>mogul@wrl.dec.com</email></address>
3398    </author>
3399    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
3400      <organization>MIT Laboratory for Computer Science</organization>
3401      <address><email>frystyk@w3.org</email></address>
3402    </author>
3403    <author initials="L." surname="Masinter" fullname="L. Masinter">
3404      <organization>Xerox Corporation</organization>
3405      <address><email>masinter@parc.xerox.com</email></address>
3406    </author>
3407    <author initials="P." surname="Leach" fullname="P. Leach">
3408      <organization>Microsoft Corporation</organization>
3409      <address><email>paulle@microsoft.com</email></address>
3410    </author>
3411    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
3412      <organization>W3C</organization>
3413      <address><email>timbl@w3.org</email></address>
3414    </author>
3415    <date month="June" year="1999"/>
3416  </front>
3417  <seriesInfo name="RFC" value="2616"/>
3418</reference>
3419
3420<reference anchor='RFC2817'>
3421  <front>
3422    <title>Upgrading to TLS Within HTTP/1.1</title>
3423    <author initials='R.' surname='Khare' fullname='R. Khare'>
3424      <organization>4K Associates / UC Irvine</organization>
3425      <address><email>rohit@4K-associates.com</email></address>
3426    </author>
3427    <author initials='S.' surname='Lawrence' fullname='S. Lawrence'>
3428      <organization>Agranat Systems, Inc.</organization>
3429      <address><email>lawrence@agranat.com</email></address>
3430    </author>
3431    <date year='2000' month='May' />
3432  </front>
3433  <seriesInfo name='RFC' value='2817' />
3434</reference>
3435
3436<reference anchor='RFC3864'>
3437  <front>
3438    <title>Registration Procedures for Message Header Fields</title>
3439    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
3440      <organization>Nine by Nine</organization>
3441      <address><email>GK-IETF@ninebynine.org</email></address>
3442    </author>
3443    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
3444      <organization>BEA Systems</organization>
3445      <address><email>mnot@pobox.com</email></address>
3446    </author>
3447    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
3448      <organization>HP Labs</organization>
3449      <address><email>JeffMogul@acm.org</email></address>
3450    </author>
3451    <date year='2004' month='September' />
3452  </front>
3453  <seriesInfo name='BCP' value='90' />
3454  <seriesInfo name='RFC' value='3864' />
3455</reference>
3456
3457<reference anchor='RFC5226'>
3458  <front>
3459    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
3460    <author initials='T.' surname='Narten' fullname='T. Narten'>
3461      <organization>IBM</organization>
3462      <address><email>narten@us.ibm.com</email></address>
3463    </author>
3464    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
3465      <organization>Google</organization>
3466      <address><email>Harald@Alvestrand.no</email></address>
3467    </author>
3468    <date year='2008' month='May' />
3469  </front>
3470  <seriesInfo name='BCP' value='26' />
3471  <seriesInfo name='RFC' value='5226' />
3472</reference>
3473
3474<reference anchor="RFC5322">
3475  <front>
3476    <title>Internet Message Format</title>
3477    <author initials="P." surname="Resnick" fullname="P. Resnick">
3478      <organization>Qualcomm Incorporated</organization>
3479    </author>
3480    <date year="2008" month="October"/>
3481  </front> 
3482  <seriesInfo name="RFC" value="5322"/>
3483</reference>
3484
3485<reference anchor='RFC5789'>
3486  <front>
3487    <title>PATCH Method for HTTP</title>
3488    <author initials='L.' surname='Dusseault' fullname='L. Dusseault'>
3489      <organization>Linden Lab</organization>
3490    </author>
3491    <author initials='J.' surname='Snell' fullname='J. Snell' />
3492    <date year='2010' month='March' />
3493  </front>
3494  <seriesInfo name='RFC' value='5789' />
3495</reference>
3496
3497</references>
3498
3499<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
3500<t>
3501  This document takes over the Status Code Registry, previously defined
3502  in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/>.
3503  (<xref target="status.code.registry"/>)
3504</t>
3505<t>
3506  Clarify definition of POST.
3507  (<xref target="POST"/>)
3508</t>
3509<t>
3510  Remove requirement to handle all Content-* header fields; ban use of
3511  Content-Range with PUT.
3512  (<xref target="PUT"/>)
3513</t>
3514<t>
3515  Take over definition of CONNECT method from <xref target="RFC2817"/>.
3516  (<xref target="CONNECT"/>)
3517</t>
3518<t>
3519  Broadened the definition of 203 (Non-Authoritative Information) to include
3520  cases of payload transformations as well.
3521  (<xref target="status.203"/>)
3522</t>
3523<t>
3524  Failed to consider that there are
3525  many other request methods that are safe to automatically redirect,
3526  and further that the user agent is able to make that determination
3527  based on the request method semantics.
3528  (Sections <xref format="counter" target="status.301"/>,
3529  <xref format="counter" target="status.302"/> and
3530  <xref format="counter" target="status.307"/>)
3531</t>
3532<t>
3533  Deprecate 305 Use Proxy status code, because user agents did not implement it.
3534  It used to indicate that the target resource must be accessed through the
3535  proxy given by the Location field. The Location field gave the URI of the
3536  proxy. The recipient was expected to repeat this single request via the proxy.
3537  (<xref target="status.305"/>)
3538</t>
3539<t>
3540  Define status 426 (Upgrade Required) (this was incorporated from
3541  <xref target="RFC2817"/>).
3542  (<xref target="status.426"/>)
3543</t>
3544<t>
3545  Change ABNF productions for header fields to only define the field value.
3546  (<xref target="header.fields"/>)
3547</t>
3548<t>
3549  Reclassify "Allow" as response header field, removing the option to
3550  specify it in a PUT request.
3551  Relax the server requirement on the contents of the Allow header field and
3552  remove requirement on clients to always trust the header field value.
3553  (<xref target="header.allow"/>)
3554</t>
3555<t>
3556  Correct syntax of Location header field to allow URI references (including
3557  relative references and fragments), as referred symbol "absoluteURI" wasn't
3558  what was expected, and add some clarifications as to when use of fragments
3559  would not be appropriate.
3560  (<xref target="header.location"/>)
3561</t>
3562<t>
3563  Restrict Max-Forwards header field to OPTIONS and TRACE (previously,
3564  extension methods could have used it as well).
3565  (<xref target="header.max-forwards"/>)
3566</t>
3567<t>
3568  Allow Referer field value of "about:blank" as alternative to not specifying it.
3569  (<xref target="header.referer"/>)
3570</t>
3571<t>
3572  In the description of the Server header field, the Via field
3573  was described as a SHOULD. The requirement was and is stated
3574  correctly in the description of the Via header field in &header-via;.
3575  (<xref target="header.server"/>)
3576</t>
3577</section>
3578
3579<?BEGININC p2-semantics.abnf-appendix ?>
3580<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
3581<figure>
3582<artwork type="abnf" name="p2-semantics.parsed-abnf">
3583<x:ref>Allow</x:ref> = [ ( "," / Method ) *( OWS "," [ OWS Method ] ) ]
3584
3585<x:ref>Expect</x:ref> = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] )
3586
3587<x:ref>From</x:ref> = mailbox
3588
3589<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part1], Section 6.1&gt;
3590
3591<x:ref>Location</x:ref> = URI-reference
3592
3593<x:ref>Max-Forwards</x:ref> = 1*DIGIT
3594<x:ref>Method</x:ref> = token
3595
3596<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
3597
3598<x:ref>RWS</x:ref> = &lt;RWS, defined in [Part1], Section 1.2.2&gt;
3599<x:ref>Reason-Phrase</x:ref> = *( WSP / VCHAR / obs-text )
3600<x:ref>Referer</x:ref> = absolute-URI / partial-URI
3601<x:ref>Retry-After</x:ref> = HTTP-date / delta-seconds
3602
3603<x:ref>Server</x:ref> = product *( RWS ( product / comment ) )
3604<x:ref>Status-Code</x:ref> = 3DIGIT
3605
3606<x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in [Part1], Section 2.7&gt;
3607<x:ref>User-Agent</x:ref> = product *( RWS ( product / comment ) )
3608
3609<x:ref>absolute-URI</x:ref> = &lt;absolute-URI, defined in [Part1], Section 2.7&gt;
3610
3611<x:ref>comment</x:ref> = &lt;comment, defined in [Part1], Section 3.2&gt;
3612
3613<x:ref>delta-seconds</x:ref> = 1*DIGIT
3614
3615<x:ref>expect-params</x:ref> = ";" token [ "=" ( token / quoted-string ) ]
3616<x:ref>expectation</x:ref> = "100-continue" / expectation-extension
3617<x:ref>expectation-extension</x:ref> = token [ "=" ( token / quoted-string )
3618 *expect-params ]
3619
3620<x:ref>mailbox</x:ref> = &lt;mailbox, defined in [RFC5322], Section 3.4&gt;
3621
3622<x:ref>obs-text</x:ref> = &lt;obs-text, defined in [Part1], Section 1.2.2&gt;
3623
3624<x:ref>partial-URI</x:ref> = &lt;partial-URI, defined in [Part1], Section 2.7&gt;
3625<x:ref>product</x:ref> = &lt;product, defined in [Part1], Section 6.3&gt;
3626
3627<x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in [Part1], Section 1.2.2&gt;
3628
3629<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 1.2.2&gt;
3630</artwork>
3631</figure>
3632<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
3633; Allow defined but not used
3634; Expect defined but not used
3635; From defined but not used
3636; Location defined but not used
3637; Max-Forwards defined but not used
3638; Reason-Phrase defined but not used
3639; Referer defined but not used
3640; Retry-After defined but not used
3641; Server defined but not used
3642; Status-Code defined but not used
3643; User-Agent defined but not used
3644</artwork></figure></section>
3645<?ENDINC p2-semantics.abnf-appendix ?>
3646
3647<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
3648
3649<section title="Since RFC 2616">
3650<t>
3651  Extracted relevant partitions from <xref target="RFC2616"/>.
3652</t>
3653</section>
3654
3655<section title="Since draft-ietf-httpbis-p2-semantics-00">
3656<t>
3657  Closed issues:
3658  <list style="symbols"> 
3659    <t>
3660      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/5"/>:
3661      "Via is a MUST"
3662      (<eref target="http://purl.org/NET/http-errata#via-must"/>)
3663    </t>
3664    <t>
3665      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/6"/>:
3666      "Fragments allowed in Location"
3667      (<eref target="http://purl.org/NET/http-errata#location-fragments"/>)
3668    </t>
3669    <t>
3670      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3671      "Safe Methods vs Redirection"
3672      (<eref target="http://purl.org/NET/http-errata#saferedirect"/>)
3673    </t>
3674    <t>
3675      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/17"/>:
3676      "Revise description of the POST method"
3677      (<eref target="http://purl.org/NET/http-errata#post"/>)
3678    </t>
3679    <t>
3680      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
3681      "Normative and Informative references"
3682    </t>
3683    <t>
3684      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/42"/>:
3685      "RFC2606 Compliance"
3686    </t>
3687    <t>
3688      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/65"/>:
3689      "Informative references"
3690    </t>
3691    <t>
3692      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/84"/>:
3693      "Redundant cross-references"
3694    </t>
3695  </list>
3696</t>
3697<t>
3698  Other changes:
3699  <list style="symbols"> 
3700    <t>
3701      Move definitions of 304 and 412 condition codes to <xref target="Part4"/>
3702    </t>
3703  </list>
3704</t>
3705</section>
3706
3707<section title="Since draft-ietf-httpbis-p2-semantics-01">
3708<t>
3709  Closed issues:
3710  <list style="symbols"> 
3711    <t>
3712      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/21"/>:
3713      "PUT side effects"
3714    </t>
3715    <t>
3716      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/91"/>:
3717      "Duplicate Host header requirements"
3718    </t>
3719  </list>
3720</t>
3721<t>
3722  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3723  <list style="symbols"> 
3724    <t>
3725      Move "Product Tokens" section (back) into Part 1, as "token" is used
3726      in the definition of the Upgrade header field.
3727    </t>
3728    <t>
3729      Add explicit references to BNF syntax and rules imported from other parts of the specification.
3730    </t>
3731    <t>
3732      Copy definition of delta-seconds from Part6 instead of referencing it.
3733    </t>
3734  </list>
3735</t>
3736</section>
3737
3738<section title="Since draft-ietf-httpbis-p2-semantics-02" anchor="changes.since.02">
3739<t>
3740  Closed issues:
3741  <list style="symbols"> 
3742    <t>
3743      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/24"/>:
3744      "Requiring Allow in 405 responses"
3745    </t>
3746    <t>
3747      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/59"/>:
3748      "Status Code Registry"
3749    </t>
3750    <t>
3751      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/61"/>:
3752      "Redirection vs. Location"
3753    </t>
3754    <t>
3755      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/70"/>:
3756      "Cacheability of 303 response"
3757    </t>
3758    <t>
3759      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/76"/>:
3760      "305 Use Proxy"
3761    </t>
3762    <t>
3763      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/105"/>:
3764      "Classification for Allow header"
3765    </t>
3766    <t>
3767      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
3768      "PUT - 'store under' vs 'store at'"
3769    </t>
3770  </list>
3771</t>
3772<t>
3773  Ongoing work on IANA Message Header Field Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
3774  <list style="symbols"> 
3775    <t>
3776      Reference RFC 3984, and update header field registrations for headers defined
3777      in this document.
3778    </t>
3779  </list>
3780</t>
3781<t>
3782  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3783  <list style="symbols"> 
3784    <t>
3785      Replace string literals when the string really is case-sensitive (method).
3786    </t>
3787  </list>
3788</t>
3789</section>
3790
3791<section title="Since draft-ietf-httpbis-p2-semantics-03" anchor="changes.since.03">
3792<t>
3793  Closed issues:
3794  <list style="symbols"> 
3795    <t>
3796      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/98"/>:
3797      "OPTIONS request bodies"
3798    </t>
3799    <t>
3800      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/119"/>:
3801      "Description of CONNECT should refer to RFC2817"
3802    </t>
3803    <t>
3804      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/125"/>:
3805      "Location Content-Location reference request/response mixup"
3806    </t>
3807  </list>
3808</t>
3809<t>
3810  Ongoing work on Method Registry (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/72"/>):
3811  <list style="symbols"> 
3812    <t>
3813      Added initial proposal for registration process, plus initial
3814      content (non-HTTP/1.1 methods to be added by a separate specification).
3815    </t>
3816  </list>
3817</t>
3818</section>
3819
3820<section title="Since draft-ietf-httpbis-p2-semantics-04" anchor="changes.since.04">
3821<t>
3822  Closed issues:
3823  <list style="symbols"> 
3824    <t>
3825      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/103"/>:
3826      "Content-*"
3827    </t>
3828    <t>
3829      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/132"/>:
3830      "RFC 2822 is updated by RFC 5322"
3831    </t>
3832  </list>
3833</t>
3834<t>
3835  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3836  <list style="symbols"> 
3837    <t>
3838      Use "/" instead of "|" for alternatives.
3839    </t>
3840    <t>
3841      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
3842      whitespace ("OWS") and required whitespace ("RWS").
3843    </t>
3844    <t>
3845      Rewrite ABNFs to spell out whitespace rules, factor out
3846      header field value format definitions.
3847    </t>
3848  </list>
3849</t>
3850</section>
3851
3852<section title="Since draft-ietf-httpbis-p2-semantics-05" anchor="changes.since.05">
3853<t>
3854  Closed issues:
3855  <list style="symbols"> 
3856    <t>
3857      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/94"/>:
3858      "Reason-Phrase BNF"
3859    </t>
3860  </list>
3861</t>
3862<t>
3863  Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3864  <list style="symbols"> 
3865    <t>
3866      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
3867    </t>
3868  </list>
3869</t>
3870</section>
3871
3872<section title="Since draft-ietf-httpbis-p2-semantics-06" anchor="changes.since.06">
3873<t>
3874  Closed issues:
3875  <list style="symbols"> 
3876    <t>
3877      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/144"/>:
3878      "Clarify when Referer is sent"
3879    </t>
3880    <t>
3881      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/164"/>:
3882      "status codes vs methods"
3883    </t>
3884    <t>
3885      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/170"/>:
3886      "Do not require "updates" relation for specs that register status codes or method names"
3887    </t>
3888  </list>
3889</t>
3890</section>
3891
3892<section title="Since draft-ietf-httpbis-p2-semantics-07" anchor="changes.since.07">
3893<t>
3894  Closed issues:
3895  <list style="symbols"> 
3896    <t>
3897      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/27"/>:
3898      "Idempotency"
3899    </t>
3900    <t>
3901      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/33"/>:
3902      "TRACE security considerations"
3903    </t>
3904    <t>
3905      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/110"/>:
3906      "Clarify rules for determining what entities a response carries"
3907    </t>
3908    <t>
3909      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/140"/>:
3910      "update note citing RFC 1945 and 2068"
3911    </t>
3912    <t>
3913      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/182"/>:
3914      "update note about redirect limit"
3915    </t>
3916    <t>
3917      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/191"/>:
3918      "Location header ABNF should use 'URI'"
3919    </t>
3920    <t>
3921      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/192"/>:
3922      "fragments in Location vs status 303"
3923    </t>
3924    <t>
3925      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/198"/>:
3926      "move IANA registrations for optional status codes"
3927    </t>
3928  </list>
3929</t>
3930<t>
3931  Partly resolved issues:
3932  <list style="symbols"> 
3933    <t>
3934      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/171"/>:
3935      "Are OPTIONS and TRACE safe?"
3936    </t>
3937  </list>
3938</t>
3939</section>
3940
3941<section title="Since draft-ietf-httpbis-p2-semantics-08" anchor="changes.since.08">
3942<t>
3943  Closed issues:
3944  <list style="symbols"> 
3945    <t>
3946      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3947      "Safe Methods vs Redirection" (we missed the introduction to the 3xx
3948      status codes when fixing this previously)
3949    </t>
3950  </list>
3951</t>
3952</section>
3953
3954<section title="Since draft-ietf-httpbis-p2-semantics-09" anchor="changes.since.09">
3955<t>
3956  Closed issues:
3957  <list style="symbols"> 
3958    <t>
3959      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/43"/>:
3960      "Fragment combination / precedence during redirects"
3961    </t>
3962  </list>
3963</t>
3964<t>
3965  Partly resolved issues:
3966  <list style="symbols"> 
3967    <t>
3968      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/185"/>:
3969      "Location header payload handling"
3970    </t>
3971    <t>
3972      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/196"/>:
3973      "Term for the requested resource's URI"
3974    </t>
3975  </list>
3976</t>
3977</section>
3978
3979<section title="Since draft-ietf-httpbis-p2-semantics-10" anchor="changes.since.10">
3980<t>
3981  Closed issues:
3982  <list style="symbols"> 
3983    <t>
3984      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/69"/>:
3985      "Clarify 'Requested Variant'"
3986    </t>
3987    <t>
3988      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/109"/>:
3989      "Clarify entity / representation / variant terminology"
3990    </t>
3991    <t>
3992      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/139"/>:
3993      "Methods and Caching"
3994    </t>
3995    <t>
3996      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/190"/>:
3997      "OPTIONS vs Max-Forwards"
3998    </t>
3999    <t>
4000      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/199"/>:
4001      "Status codes and caching"
4002    </t>
4003    <t>
4004      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>:
4005      "consider removing the 'changes from 2068' sections"
4006    </t>
4007  </list>
4008</t>
4009</section>
4010
4011<section title="Since draft-ietf-httpbis-p2-semantics-11" anchor="changes.since.11">
4012<t>
4013  Closed issues:
4014  <list style="symbols"> 
4015    <t>
4016      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/229"/>:
4017      "Considerations for new status codes"
4018    </t>
4019    <t>
4020      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/230"/>:
4021      "Considerations for new methods"
4022    </t>
4023    <t>
4024      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/232"/>:
4025      "User-Agent guidelines" (relating to the 'User-Agent' header field)
4026    </t>
4027  </list>
4028</t>
4029</section>
4030
4031<section title="Since draft-ietf-httpbis-p2-semantics-12" anchor="changes.since.12">
4032<t>
4033  Closed issues:
4034  <list style="symbols"> 
4035    <t>
4036      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/43"/>:
4037      "Fragment combination / precedence during redirects" (added warning
4038      about having a fragid on the redirect may cause inconvenience in
4039      some cases)
4040    </t>
4041    <t>
4042      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/79"/>:
4043      "Content-* vs. PUT"
4044    </t>
4045    <t>
4046      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/88"/>:
4047      "205 Bodies"
4048    </t>
4049    <t>
4050      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/102"/>:
4051      "Understanding Content-* on non-PUT requests"
4052    </t>
4053    <t>
4054      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/103"/>:
4055      "Content-*"
4056    </t>
4057    <t>
4058      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/104"/>:
4059      "Header type defaulting"
4060    </t>
4061    <t>
4062      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
4063      "PUT - 'store under' vs 'store at'"
4064    </t>
4065    <t>
4066      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/137"/>:
4067      "duplicate ABNF for Reason-Phrase"
4068    </t>
4069    <t>
4070      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/180"/>:
4071      "Note special status of Content-* prefix in header registration procedures"
4072    </t>
4073    <t>
4074      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/203"/>:
4075      "Max-Forwards vs extension methods"
4076    </t>
4077    <t>
4078      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/213"/>:
4079      "What is the value space of HTTP status codes?" (actually fixed in
4080      draft-ietf-httpbis-p2-semantics-11)
4081    </t>
4082    <t>
4083      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/224"/>:
4084      "Header Classification"
4085    </t>
4086    <t>
4087      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/225"/>:
4088      "PUT side effect: invalidation or just stale?"
4089    </t>
4090    <t>
4091      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/226"/>:
4092      "proxies not supporting certain methods"
4093    </t>
4094    <t>
4095      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/239"/>:
4096      "Migrate CONNECT from RFC2817 to p2"
4097    </t>
4098    <t>
4099      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/240"/>:
4100      "Migrate Upgrade details from RFC2817"
4101    </t>
4102    <t>
4103      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/267"/>:
4104      "clarify PUT semantics'"
4105    </t>
4106    <t>
4107      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/275"/>:
4108      "duplicate ABNF for 'Method'"
4109    </t>
4110    <t>
4111      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/276"/>:
4112      "untangle ABNFs for header fields"
4113    </t>
4114  </list>
4115</t>
4116</section>
4117
4118<section title="Since draft-ietf-httpbis-p2-semantics-13" anchor="changes.since.13">
4119<t>
4120  Closed issues:
4121  <list style="symbols"> 
4122    <t>
4123      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/276"/>:
4124      "untangle ABNFs for header fields"
4125    </t>
4126    <t>
4127      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/251"/>:
4128      "message-body in CONNECT request"
4129    </t>
4130  </list>
4131</t>
4132</section>
4133
4134<section title="Since draft-ietf-httpbis-p2-semantics-14" anchor="changes.since.14">
4135<t>
4136  Closed issues:
4137  <list style="symbols"> 
4138    <t>
4139      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/255"/>:
4140      "Clarify status code for rate limiting"
4141    </t>
4142    <t>
4143      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/294"/>:
4144      "clarify 403 forbidden"
4145    </t>
4146    <t>
4147      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/296"/>:
4148      "Clarify 203 Non-Authoritative Information"
4149    </t>
4150  </list>
4151</t>
4152</section>
4153</section>
4154
4155</back>
4156</rfc>
Note: See TracBrowser for help on using the repository browser.