source: draft-ietf-httpbis/latest/p2-semantics.xml @ 1145

Last change on this file since 1145 was 1145, checked in by julian.reschke@…, 9 years ago

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

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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 "March">
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 full-date                  "<xref target='Part1' x:rel='#date.time.formats.full.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
32  <!ENTITY http-url                   "<xref target='Part1' x:rel='#http-url' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
33  <!ENTITY http-version               "<xref target='Part1' x:rel='#http.version' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
34  <!ENTITY use100                     "<xref target='Part1' x:rel='#use.of.the.100.status' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
35  <!ENTITY qvalue                     "<xref target='Part3' x:rel='#quality.values' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
36  <!ENTITY request-target             "<xref target='Part1' x:rel='#request-target' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
37  <!ENTITY header-accept              "<xref target='Part3' x:rel='#header.accept' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
38  <!ENTITY header-accept-charset      "<xref target='Part3' x:rel='#header.accept-charset' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
39  <!ENTITY header-accept-encoding     "<xref target='Part3' x:rel='#header.accept-encoding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
40  <!ENTITY header-accept-language     "<xref target='Part3' x:rel='#header.accept-language' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
41  <!ENTITY header-accept-ranges       "<xref target='Part5' x:rel='#header.accept-ranges' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
42  <!ENTITY header-age                 "<xref target='Part6' x:rel='#header.age' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
43  <!ENTITY header-authorization       "<xref target='Part7' x:rel='#header.authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
44  <!ENTITY header-cache-control       "<xref target='Part6' x:rel='#header.cache-control' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
45  <!ENTITY header-content-location    "<xref target='Part3' x:rel='#header.content-location' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
46  <!ENTITY header-content-range       "<xref target='Part5' x:rel='#header.content-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
47  <!ENTITY header-etag                "<xref target='Part4' x:rel='#header.etag' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
48  <!ENTITY header-expires             "<xref target='Part6' x:rel='#header.expires' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
49  <!ENTITY header-fields              "<xref target='Part1' x:rel='#header.fields' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
50  <!ENTITY header-host                "<xref target='Part1' x:rel='#header.host' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
51  <!ENTITY header-if-match            "<xref target='Part4' x:rel='#header.if-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
52  <!ENTITY header-if-modified-since   "<xref target='Part4' x:rel='#header.if-modified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
53  <!ENTITY header-if-none-match       "<xref target='Part4' x:rel='#header.if-none-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
54  <!ENTITY header-if-range            "<xref target='Part5' x:rel='#header.if-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
55  <!ENTITY header-if-unmodified-since "<xref target='Part4' x:rel='#header.if-unmodified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
56  <!ENTITY header-pragma              "<xref target='Part6' x:rel='#header.pragma' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
57  <!ENTITY header-proxy-authenticate  "<xref target='Part7' x:rel='#header.proxy-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
58  <!ENTITY header-proxy-authorization "<xref target='Part7' x:rel='#header.proxy-authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
59  <!ENTITY header-range               "<xref target='Part5' x:rel='#header.range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
60  <!ENTITY header-upgrade             "<xref target='Part1' x:rel='#header.upgrade' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
61  <!ENTITY header-te                  "<xref target='Part1' x:rel='#header.te' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
62  <!ENTITY header-vary                "<xref target='Part6' x:rel='#header.vary' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
63  <!ENTITY header-via                 "<xref target='Part1' x:rel='#header.via' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
64  <!ENTITY header-warning             "<xref target='Part6' x:rel='#header.warning' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
65  <!ENTITY header-www-authenticate    "<xref target='Part7' x:rel='#header.www-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
66  <!ENTITY message-body               "<xref target='Part1' x:rel='#message.body' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
67  <!ENTITY product-tokens             "<xref target='Part1' x:rel='#product.tokens' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
68  <!ENTITY media-type-message-http    "<xref target='Part1' x:rel='#internet.media.type.message.http' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
69  <!ENTITY status-206                 "<xref target='Part5' x:rel='#status.206' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
70  <!ENTITY status-304                 "<xref target='Part4' x:rel='#status.304' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
71  <!ENTITY status-401                 "<xref target='Part7' x:rel='#status.401' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
72  <!ENTITY status-407                 "<xref target='Part7' x:rel='#status.407' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
73  <!ENTITY status-412                 "<xref target='Part4' x:rel='#status.412' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
74  <!ENTITY status-416                 "<xref target='Part5' x:rel='#status.416' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
75  <!ENTITY p4-status-codes            "<xref target='Part4' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
76  <!ENTITY p5-status-codes            "<xref target='Part5' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
77  <!ENTITY p7-status-codes            "<xref target='Part7' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
78  <!ENTITY p6-heuristic               "<xref target='Part6' x:rel='#heuristic.freshness' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
79  <!ENTITY p6-explicit                "<xref target='Part6' x:rel='#calculating.freshness.lifetime' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
80  <!ENTITY p6-invalid                 "<xref target='Part6' x:rel='#invalidation.after.updates.or.deletions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
81]>
82<?rfc toc="yes" ?>
83<?rfc symrefs="yes" ?>
84<?rfc sortrefs="yes" ?>
85<?rfc compact="yes"?>
86<?rfc subcompact="no" ?>
87<?rfc linkmailto="no" ?>
88<?rfc editing="no" ?>
89<?rfc comments="yes"?>
90<?rfc inline="yes"?>
91<?rfc rfcedstyle="yes"?>
92<?rfc-ext allow-markup-in-artwork="yes" ?>
93<?rfc-ext include-references-in-index="yes" ?>
94<rfc obsoletes="2616" updates="2817" category="std" x:maturity-level="draft"
95     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"
96     xmlns:x='http://purl.org/net/xml2rfc/ext'
97     xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
98<front>
99
100  <title abbrev="HTTP/1.1, Part 2">HTTP/1.1, part 2: Message Semantics</title>
101
102  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
103    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
104    <address>
105      <postal>
106        <street>345 Park Ave</street>
107        <city>San Jose</city>
108        <region>CA</region>
109        <code>95110</code>
110        <country>USA</country>
111      </postal>
112      <email>fielding@gbiv.com</email>
113      <uri>http://roy.gbiv.com/</uri>
114    </address>
115  </author>
116
117  <author initials="J." surname="Gettys" fullname="Jim Gettys">
118    <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
119    <address>
120      <postal>
121        <street>21 Oak Knoll Road</street>
122        <city>Carlisle</city>
123        <region>MA</region>
124        <code>01741</code>
125        <country>USA</country>
126      </postal>
127      <email>jg@freedesktop.org</email>
128      <uri>http://gettys.wordpress.com/</uri>
129    </address>
130  </author>
131 
132  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
133    <organization abbrev="HP">Hewlett-Packard Company</organization>
134    <address>
135      <postal>
136        <street>HP Labs, Large Scale Systems Group</street>
137        <street>1501 Page Mill Road, MS 1177</street>
138        <city>Palo Alto</city>
139        <region>CA</region>
140        <code>94304</code>
141        <country>USA</country>
142      </postal>
143      <email>JeffMogul@acm.org</email>
144    </address>
145  </author>
146
147  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
148    <organization abbrev="Microsoft">Microsoft Corporation</organization>
149    <address>
150      <postal>
151        <street>1 Microsoft Way</street>
152        <city>Redmond</city>
153        <region>WA</region>
154        <code>98052</code>
155        <country>USA</country>
156      </postal>
157      <email>henrikn@microsoft.com</email>
158    </address>
159  </author>
160
161  <author initials="L." surname="Masinter" fullname="Larry Masinter">
162    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
163    <address>
164      <postal>
165        <street>345 Park Ave</street>
166        <city>San Jose</city>
167        <region>CA</region>
168        <code>95110</code>
169        <country>USA</country>
170      </postal>
171      <email>LMM@acm.org</email>
172      <uri>http://larry.masinter.net/</uri>
173    </address>
174  </author>
175 
176  <author initials="P." surname="Leach" fullname="Paul J. Leach">
177    <organization abbrev="Microsoft">Microsoft Corporation</organization>
178    <address>
179      <postal>
180        <street>1 Microsoft Way</street>
181        <city>Redmond</city>
182        <region>WA</region>
183        <code>98052</code>
184      </postal>
185      <email>paulle@microsoft.com</email>
186    </address>
187  </author>
188   
189  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
190    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
191    <address>
192      <postal>
193        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
194        <street>The Stata Center, Building 32</street>
195        <street>32 Vassar Street</street>
196        <city>Cambridge</city>
197        <region>MA</region>
198        <code>02139</code>
199        <country>USA</country>
200      </postal>
201      <email>timbl@w3.org</email>
202      <uri>http://www.w3.org/People/Berners-Lee/</uri>
203    </address>
204  </author>
205
206  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
207    <organization abbrev="W3C">World Wide Web Consortium</organization>
208    <address>
209      <postal>
210        <street>W3C / ERCIM</street>
211        <street>2004, rte des Lucioles</street>
212        <city>Sophia-Antipolis</city>
213        <region>AM</region>
214        <code>06902</code>
215        <country>France</country>
216      </postal>
217      <email>ylafon@w3.org</email>
218      <uri>http://www.raubacapeu.net/people/yves/</uri>
219    </address>
220  </author>
221
222  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
223    <organization abbrev="greenbytes">greenbytes GmbH</organization>
224    <address>
225      <postal>
226        <street>Hafenweg 16</street>
227        <city>Muenster</city><region>NW</region><code>48155</code>
228        <country>Germany</country>
229      </postal>
230      <phone>+49 251 2807760</phone>
231      <facsimile>+49 251 2807761</facsimile>
232      <email>julian.reschke@greenbytes.de</email>
233      <uri>http://greenbytes.de/tech/webdav/</uri>
234    </address>
235  </author>
236
237  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
238  <workgroup>HTTPbis Working Group</workgroup>
239
240<abstract>
241<t>
242   The Hypertext Transfer Protocol (HTTP) is an application-level
243   protocol for distributed, collaborative, hypermedia information
244   systems. HTTP has been in use by the World Wide Web global information
245   initiative since 1990. This document is Part 2 of the seven-part specification
246   that defines the protocol referred to as "HTTP/1.1" and, taken together,
247   obsoletes RFC 2616.  Part 2 defines the semantics of HTTP messages
248   as expressed by request methods, request-header fields, response status codes,
249   and response-header fields.
250</t>
251</abstract>
252
253<note title="Editorial Note (To be removed by RFC Editor)">
254  <t>
255    Discussion of this draft should take place on the HTTPBIS working group
256    mailing list (ietf-http-wg@w3.org). The current issues list is
257    at <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/>
258    and related documents (including fancy diffs) can be found at
259    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
260  </t>
261  <t>
262    The changes in this draft are summarized in <xref target="changes.since.12"/>.
263  </t>
264</note>
265</front>
266<middle>
267<section title="Introduction" anchor="introduction">
268<t>
269   This document defines HTTP/1.1 request and response semantics.  Each HTTP
270   message, as defined in &messaging;, is in the form of either a request or
271   a response.  An HTTP server listens on a connection for HTTP requests and
272   responds to each request, in the order received on that connection, with
273   one or more HTTP response messages.  This document defines the commonly
274   agreed upon semantics of the HTTP uniform interface, the intentions defined
275   by each request method, and the various response messages that might be
276   expected as a result of applying that method to the target resource.
277</t>
278<t>
279   This document is currently disorganized in order to minimize the changes
280   between drafts and enable reviewers to see the smaller errata changes.
281   A future draft will reorganize the sections to better reflect the content.
282   In particular, the sections will be ordered according to the typical
283   processing of an HTTP request message (after message parsing): resource
284   mapping, general header fields, methods, request modifiers, response
285   status, and resource metadata.  The current mess reflects how widely
286   dispersed these topics and associated requirements had become in
287   <xref target="RFC2616"/>.
288</t>
289
290<section title="Requirements" anchor="intro.requirements">
291<t>
292   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
293   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
294   document are to be interpreted as described in <xref target="RFC2119"/>.
295</t>
296<t>
297   An implementation is not compliant if it fails to satisfy one or more
298   of the "MUST" or "REQUIRED" level requirements for the protocols it
299   implements. An implementation that satisfies all the "MUST" or "REQUIRED"
300   level and all the "SHOULD" level requirements for its protocols is said
301   to be "unconditionally compliant"; one that satisfies all the "MUST"
302   level requirements but not all the "SHOULD" level requirements for its
303   protocols is said to be "conditionally compliant".
304</t>
305</section>
306
307<section title="Syntax Notation" anchor="notation">
308  <x:anchor-alias value="CR"/>
309  <x:anchor-alias value="DIGIT"/>
310  <x:anchor-alias value="LF"/>
311  <x:anchor-alias value="VCHAR"/>
312  <x:anchor-alias value="WSP"/>
313<t>
314  This specification uses the ABNF syntax defined in &notation; (which
315  extends the syntax defined in <xref target="RFC5234"/> with a list rule).
316  <xref target="collected.abnf"/> shows the collected ABNF, with the list
317  rule expanded.
318</t>
319<t>
320  The following core rules are included by
321  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
322  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
323  DIGIT (decimal 0-9), DQUOTE (double quote),
324  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
325  OCTET (any 8-bit sequence of data), SP (space),
326  VCHAR (any visible USASCII character),
327  and WSP (whitespace).
328</t>
329
330<section title="Core Rules" anchor="core.rules">
331  <x:anchor-alias value="obs-text"/>
332  <x:anchor-alias value="quoted-string"/>
333  <x:anchor-alias value="token"/>
334  <x:anchor-alias value="OWS"/>
335  <x:anchor-alias value="RWS"/>
336<t>
337  The core rules below are defined in &basic-rules;:
338</t>
339<figure><artwork type="abnf2616">
340  <x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in &basic-rules;&gt;
341  <x:ref>token</x:ref>         = &lt;token, defined in &basic-rules;&gt;
342  <x:ref>OWS</x:ref>           = &lt;OWS, defined in &basic-rules;&gt;
343  <x:ref>RWS</x:ref>           = &lt;RWS, defined in &basic-rules;&gt;
344  <x:ref>obs-text</x:ref>      = &lt;obs-text, defined in &basic-rules;&gt;
345</artwork></figure>
346</section>
347
348<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
349  <x:anchor-alias value="absolute-URI"/>
350  <x:anchor-alias value="Accept"/>
351  <x:anchor-alias value="Accept-Charset"/>
352  <x:anchor-alias value="Accept-Encoding"/>
353  <x:anchor-alias value="Accept-Language"/>
354  <x:anchor-alias value="Accept-Ranges"/>
355  <x:anchor-alias value="Age"/>
356  <x:anchor-alias value="Authorization"/>
357  <x:anchor-alias value="comment"/>
358  <x:anchor-alias value="ETag"/>
359  <x:anchor-alias value="Host"/>
360  <x:anchor-alias value="HTTP-date"/>
361  <x:anchor-alias value="If-Match"/>
362  <x:anchor-alias value="If-Modified-Since"/>
363  <x:anchor-alias value="If-None-Match"/>
364  <x:anchor-alias value="If-Range"/>
365  <x:anchor-alias value="If-Unmodified-Since"/>
366  <x:anchor-alias value="partial-URI"/>
367  <x:anchor-alias value="product"/>
368  <x:anchor-alias value="Proxy-Authenticate"/>
369  <x:anchor-alias value="Proxy-Authorization"/>
370  <x:anchor-alias value="Range"/>
371  <x:anchor-alias value="TE"/>
372  <x:anchor-alias value="URI-reference"/>
373  <x:anchor-alias value="Vary"/>
374  <x:anchor-alias value="WWW-Authenticate"/>
375<t>
376  The ABNF rules below are defined in other parts:
377</t>
378<figure><!--Part1--><artwork type="abnf2616">
379  <x:ref>absolute-URI</x:ref>  = &lt;absolute-URI, defined in &uri;&gt;
380  <x:ref>comment</x:ref>       = &lt;comment, defined in &header-fields;&gt;
381  <x:ref>Host</x:ref>          = &lt;Host, defined in &uri;&gt;
382  <x:ref>HTTP-date</x:ref>     = &lt;HTTP-date, defined in &full-date;&gt;
383  <x:ref>partial-URI</x:ref>   = &lt;partial-URI, defined in &uri;&gt;
384  <x:ref>product</x:ref>       = &lt;product, defined in &product-tokens;&gt;
385  <x:ref>TE</x:ref>            = &lt;TE, defined in &header-te;&gt;
386  <x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in &uri;&gt;
387</artwork></figure>
388<figure><!--Part3--><artwork type="abnf2616">
389  <x:ref>Accept</x:ref>        = &lt;Accept, defined in &header-accept;&gt;
390  <x:ref>Accept-Charset</x:ref> =
391             &lt;Accept-Charset, defined in &header-accept-charset;&gt;
392  <x:ref>Accept-Encoding</x:ref> =
393             &lt;Accept-Encoding, defined in &header-accept-encoding;&gt;
394  <x:ref>Accept-Language</x:ref> =
395             &lt;Accept-Language, defined in &header-accept-language;&gt;
396</artwork></figure>
397<figure><!--Part4--><artwork type="abnf2616">
398  <x:ref>ETag</x:ref>          = &lt;ETag, defined in &header-etag;&gt;
399  <x:ref>If-Match</x:ref>      = &lt;If-Match, defined in &header-if-match;&gt;
400  <x:ref>If-Modified-Since</x:ref> =
401             &lt;If-Modified-Since, defined in &header-if-modified-since;&gt;
402  <x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in &header-if-none-match;&gt;
403  <x:ref>If-Unmodified-Since</x:ref> =
404             &lt;If-Unmodified-Since, defined in &header-if-unmodified-since;&gt;
405</artwork></figure>
406<figure><!--Part5--><artwork type="abnf2616">
407  <x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in &header-accept-ranges;&gt;
408  <x:ref>If-Range</x:ref>      = &lt;If-Range, defined in &header-if-range;&gt;
409  <x:ref>Range</x:ref>         = &lt;Range, defined in &header-range;&gt;
410</artwork></figure>
411<figure><!--Part6--><artwork type="abnf2616">
412  <x:ref>Age</x:ref>           = &lt;Age, defined in &header-age;&gt;
413  <x:ref>Vary</x:ref>          = &lt;Vary, defined in &header-vary;&gt;
414</artwork><!--Part7--></figure>
415<figure><artwork type="abnf2616">
416  <x:ref>Authorization</x:ref> = &lt;Authorization, defined in &header-authorization;&gt;
417  <x:ref>Proxy-Authenticate</x:ref> =
418             &lt;Proxy-Authenticate, defined in &header-proxy-authenticate;&gt;
419  <x:ref>Proxy-Authorization</x:ref> =
420             &lt;Proxy-Authorization, defined in &header-proxy-authorization;&gt;
421  <x:ref>WWW-Authenticate</x:ref> =
422             &lt;WWW-Authenticate, defined in &header-www-authenticate;&gt;
423</artwork></figure>
424</section>
425</section>
426</section>
427
428<section title="Method" anchor="method">
429  <x:anchor-alias value="Method"/>
430  <x:anchor-alias value="extension-method"/>
431<t>
432   The Method token indicates the method to be performed on the target
433   resource (&effective-request-uri;). The method is case-sensitive.
434</t>
435<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Method"/>
436  <x:ref>Method</x:ref>         = <x:ref>token</x:ref>
437</artwork></figure>
438<t>
439   The list of methods allowed by a resource can be specified in an
440   Allow header field (<xref target="header.allow"/>). The status code of the response
441   always notifies the client whether a method is currently allowed on a
442   resource, since the set of allowed methods can change dynamically. An
443   origin server &SHOULD; respond with the status code 405 (Method Not Allowed)
444   if the method is known by the origin server but not allowed for the
445   resource, and 501 (Not Implemented) if the method is
446   unrecognized or not implemented by the origin server. The methods GET
447   and HEAD &MUST; be supported by all general-purpose servers. All other
448   methods are &OPTIONAL;; however, if the above methods are implemented,
449   they &MUST; be implemented with the same semantics as those specified
450   in <xref target="method.definitions"/>.
451</t>
452
453<section title="Overview of Methods" anchor="overview.of.methods">
454<t>
455  The methods listed below are defined in <xref target="method.definitions"/>.
456</t>
457<texttable align="left">
458  <ttcol>Method Name</ttcol><ttcol>Defined in...</ttcol>
459 
460  <c>OPTIONS</c> <c><xref target="OPTIONS"/></c>
461  <c>GET</c> <c><xref target="GET"/></c>
462  <c>HEAD</c> <c><xref target="HEAD"/></c>
463  <c>POST</c> <c><xref target="POST"/></c>
464  <c>PUT</c> <c><xref target="PUT"/></c>
465  <c>DELETE</c> <c><xref target="DELETE"/></c>
466  <c>TRACE</c> <c><xref target="TRACE"/></c>
467  <c>CONNECT</c> <c><xref target="CONNECT"/></c>
468</texttable>
469<t>
470  Note that this list is not exhaustive &mdash; it does not include methods defined
471  in other specifications.
472</t>
473</section>
474
475<section title="Method Registry" anchor="method.registry">
476<t>
477  The HTTP Method Registry defines the name space for the Method token in the
478  Request line of an HTTP request.
479</t>
480<t>
481  Registrations &MUST; include the following fields:
482  <list style="symbols">
483    <t>Method Name (see <xref target="method"/>)</t>
484    <t>Safe ("yes" or "no", see <xref target="safe.methods"/>)</t>
485    <t>Pointer to specification text</t>
486  </list>
487</t>
488<t>
489  Values to be added to this name space are subject to IETF review
490  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
491</t>
492<t>
493  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-methods"/>.
494</t>
495
496<section title="Considerations for New Methods" anchor="considerations.for.new.methods">
497<t>
498   When it is necessary to express new semantics for a HTTP request that
499   aren't specific to a single application or media type, and currently defined
500   methods are inadequate, it may be appropriate to register a new method.
501</t>
502<t>
503   HTTP methods are generic; that is, they are potentially applicable to any
504   resource, not just one particular media type, "type" of resource, or
505   application. As such, it is preferred that new HTTP methods be registered
506   in a document that isn't specific to a single application, so that this is
507   clear.
508</t>
509<t>
510   Due to the parsing rules defined in &message-body;, definitions of HTTP
511   methods cannot prohibit the presence of a message-body on either the request
512   or the response message (with responses to HEAD requests being the single
513   exception). Definitions of new methods cannot change this rule, but they can
514   specify that only zero-length bodies (as opposed to absent bodies) are allowed.
515</t>
516<t>
517   New method definitions need to indicate whether they are safe (<xref
518   target="safe.methods"/>) and whether they are idempotent (<xref
519   target="idempotent.methods"/>). They also need to state whether they can be
520   cached (&caching;); in particular what conditions a cache may store the
521   response, and under what conditions such a stored response may be used to
522   satisfy a subsequent request.
523</t>
524</section>
525
526</section>
527</section>
528
529<section title="Request Header Fields" anchor="request.header.fields">
530  <x:anchor-alias value="request-header"/>
531<t>
532   The request-header fields allow the client to pass additional
533   information about the request, and about the client itself, to the
534   server. These fields act as request modifiers, with semantics
535   equivalent to the parameters on a programming language method
536   invocation.
537</t>
538<texttable align="left">
539  <ttcol>Header Field Name</ttcol>
540  <ttcol>Defined in...</ttcol>
541
542  <c>Accept</c> <c>&header-accept;</c>
543  <c>Accept-Charset</c> <c>&header-accept-charset;</c>
544  <c>Accept-Encoding</c> <c>&header-accept-encoding;</c>
545  <c>Accept-Language</c> <c>&header-accept-language;</c>
546  <c>Authorization</c> <c>&header-authorization;</c>
547  <c>Expect</c> <c><xref target="header.expect"/></c>
548  <c>From</c> <c><xref target="header.from"/></c>
549  <c>Host</c> <c>&header-host;</c>
550  <c>If-Match</c> <c>&header-if-match;</c>
551  <c>If-Modified-Since</c> <c>&header-if-modified-since;</c>
552  <c>If-None-Match</c> <c>&header-if-none-match;</c>
553  <c>If-Range</c> <c>&header-if-range;</c>
554  <c>If-Unmodified-Since</c> <c>&header-if-unmodified-since;</c>
555  <c>Max-Forwards</c> <c><xref target="header.max-forwards"/></c>
556  <c>Proxy-Authorization</c> <c>&header-proxy-authorization;</c>
557  <c>Range</c> <c>&header-range;</c>
558  <c>Referer</c> <c><xref target="header.referer"/></c>
559  <c>TE</c> <c>&header-te;</c>
560  <c>User-Agent</c> <c><xref target="header.user-agent"/></c>
561</texttable>
562<t>
563   Request-header field names can be extended reliably only in
564   combination with a change in the protocol version. However, new or
565   experimental header fields &MAY; be given the semantics of request-header
566   fields if all parties in the communication recognize them to
567   be request-header fields.
568</t>
569</section>
570
571<section title="Status Code and Reason Phrase" anchor="status.code.and.reason.phrase">
572  <x:anchor-alias value="Reason-Phrase"/>
573  <x:anchor-alias value="Status-Code"/>
574  <x:anchor-alias value="extension-code"/>
575<t>
576   The Status-Code element is a 3-digit integer result code of the attempt to
577   understand and satisfy the request.
578</t>
579<t>
580   The Reason-Phrase is intended to give a short textual description of the
581   Status-Code and is intended for a human user. The client does not need
582   to examine or display the Reason-Phrase.
583</t>
584<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"/>
585  <x:ref>Status-Code</x:ref>    = 3<x:ref>DIGIT</x:ref>
586  <x:ref>Reason-Phrase</x:ref>  = *( <x:ref>WSP</x:ref> / <x:ref>VCHAR</x:ref> / <x:ref>obs-text</x:ref> )
587</artwork></figure>
588<t>
589   HTTP status codes are extensible. HTTP applications are not required
590   to understand the meaning of all registered status codes, though such
591   understanding is obviously desirable. However, applications &MUST;
592   understand the class of any status code, as indicated by the first
593   digit, and treat any unrecognized response as being equivalent to the
594   x00 status code of that class, with the exception that an
595   unrecognized response &MUST-NOT; be cached. For example, if an
596   unrecognized status code of 431 is received by the client, it can
597   safely assume that there was something wrong with its request and
598   treat the response as if it had received a 400 status code. In such
599   cases, user agents &SHOULD; present to the user the representation enclosed
600   with the response, since that representation is likely to include human-readable
601   information which will explain the unusual status.
602</t>
603
604<section title="Overview of Status Codes" anchor="overview.of.status.codes">
605<t> 
606   The status codes listed below are defined in <xref target="status.codes"/>
607   of this specification, &p4-status-codes;, &p5-status-codes;, and &p7-status-codes;.
608   The reason phrases listed here are only recommendations &mdash; they can be
609   replaced by local equivalents without affecting the protocol.
610</t>
611<texttable align="left">
612  <ttcol>Status-Code</ttcol>
613  <ttcol>Reason-Phrase</ttcol>
614  <ttcol>Defined in...</ttcol>
615 
616  <c>100</c> <c>Continue</c> <c><xref target="status.100"/></c>
617  <c>101</c> <c>Switching Protocols</c> <c><xref target="status.101"/></c>
618
619  <c>200</c> <c>OK</c> <c><xref target="status.200"/></c>
620  <c>201</c> <c>Created</c> <c><xref target="status.201"/></c>
621  <c>202</c> <c>Accepted</c> <c><xref target="status.202"/></c>
622  <c>203</c> <c>Non-Authoritative Information</c> <c><xref target="status.203"/></c>
623  <c>204</c> <c>No Content</c> <c><xref target="status.204"/></c>
624  <c>205</c> <c>Reset Content</c> <c><xref target="status.205"/></c>
625  <c>206</c> <c>Partial Content</c> <c>&status-206;</c>
626
627  <c>300</c> <c>Multiple Choices</c> <c><xref target="status.300"/></c>
628  <c>301</c> <c>Moved Permanently</c> <c><xref target="status.301"/></c>
629  <c>302</c> <c>Found</c> <c><xref target="status.302"/></c>
630  <c>303</c> <c>See Other</c> <c><xref target="status.303"/></c>
631  <c>304</c> <c>Not Modified</c> <c>&status-304;</c>
632  <c>305</c> <c>Use Proxy</c> <c><xref target="status.305"/></c>
633  <c>307</c> <c>Temporary Redirect</c> <c><xref target="status.307"/></c>
634
635  <c>400</c> <c>Bad Request</c> <c><xref target="status.400"/></c>
636  <c>401</c> <c>Unauthorized</c> <c>&status-401;</c>
637  <c>402</c> <c>Payment Required</c> <c><xref target="status.402"/></c>
638  <c>403</c> <c>Forbidden</c> <c><xref target="status.403"/></c>
639  <c>404</c> <c>Not Found</c> <c><xref target="status.404"/></c>
640  <c>405</c> <c>Method Not Allowed</c> <c><xref target="status.405"/></c>
641  <c>406</c> <c>Not Acceptable</c> <c><xref target="status.406"/></c>
642  <c>407</c> <c>Proxy Authentication Required</c> <c>&status-407;</c>
643  <c>408</c> <c>Request Time-out</c> <c><xref target="status.408"/></c>
644  <c>409</c> <c>Conflict</c> <c><xref target="status.409"/></c>
645  <c>410</c> <c>Gone</c> <c><xref target="status.410"/></c>
646  <c>411</c> <c>Length Required</c> <c><xref target="status.411"/></c>
647  <c>412</c> <c>Precondition Failed</c> <c>&status-412;</c>
648  <c>413</c> <c>Request Entity Too Large</c> <c><xref target="status.413"/></c>
649  <c>414</c> <c>URI Too Long</c> <c><xref target="status.414"/></c>
650  <c>415</c> <c>Unsupported Media Type</c> <c><xref target="status.415"/></c>
651  <c>416</c> <c>Requested range not satisfiable</c> <c>&status-416;</c>
652  <c>417</c> <c>Expectation Failed</c> <c><xref target="status.417"/></c>
653  <c>426</c> <c>Upgrade Required</c> <c><xref target="status.426"/></c>
654
655  <c>500</c> <c>Internal Server Error</c> <c><xref target="status.500"/></c>
656  <c>501</c> <c>Not Implemented</c> <c><xref target="status.501"/></c>
657  <c>502</c> <c>Bad Gateway</c> <c><xref target="status.502"/></c>
658  <c>503</c> <c>Service Unavailable</c> <c><xref target="status.503"/></c>
659  <c>504</c> <c>Gateway Time-out</c> <c><xref target="status.504"/></c>
660  <c>505</c> <c>HTTP Version not supported</c> <c><xref target="status.505"/></c>
661</texttable>
662<t>
663   Note that this list is not exhaustive &mdash; it does not include
664   extension status codes defined in other specifications.
665</t>
666</section>
667
668<section title="Status Code Registry" anchor="status.code.registry">
669<t>
670  The HTTP Status Code Registry defines the name space for the Status-Code
671  token in the Status-Line of an HTTP response.
672</t>
673<t>
674  Values to be added to this name space are subject to IETF review
675  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
676</t>
677<t>
678  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-status-codes"/>.
679</t>
680
681<section title="Considerations for New Status Codes" anchor="considerations.for.new.status.codes">
682<t>
683   When it is necessary to express new semantics for a HTTP response that
684   aren't specific to a single application or media type, and currently defined
685   status codes are inadequate, a new status code can be registered.
686</t>
687<t>
688   HTTP status codes are generic; that is, they are potentially applicable to
689   any resource, not just one particular media type, "type" of resource, or
690   application. As such, it is preferred that new HTTP status codes be
691   registered in a document that isn't specific to a single application, so
692   that this is clear.
693</t>
694<t>
695   Definitions of new HTTP status codes typically explain the request
696   conditions that produce a response containing the status code (e.g.,
697   combinations of request headers and/or method(s)), along with any
698   interactions with response headers (e.g., those that are required, those
699   that modify the semantics of the response).
700</t>
701<t>
702   New HTTP status codes are required to fall under one of the categories
703   defined in <xref target="status.codes"/>. To allow existing parsers to
704   properly handle them, new status codes cannot disallow a response body,
705   although they can mandate a zero-length response body. They can require the
706   presence of one or more particular HTTP response header(s).
707</t>
708<t>
709   Likewise, their definitions can specify that caches are allowed to use
710   heuristics to determine their freshness (see &caching;; by default, it is
711   not allowed), and can define how to determine the resource which they
712   carry a representation for (see <xref
713   target="identifying.response.associated.with.representation"/>; by default,
714   it is anonymous).
715</t>
716</section>
717
718</section>
719
720</section>
721
722<section title="Response Header Fields" anchor="response.header.fields">
723  <x:anchor-alias value="response-header"/>
724<t>
725   The response-header fields allow the server to pass additional
726   information about the response which cannot be placed in the Status-Line.
727   These header fields give information about the server and about
728   further access to the target resource (&effective-request-uri;).
729</t>
730<texttable align="left">
731  <ttcol>Method Name</ttcol><ttcol>Defined in...</ttcol>
732
733  <c>Accept-Ranges</c> <c>&header-accept-ranges;</c>
734  <c>Age</c> <c>&header-age;</c>
735  <c>Allow</c> <c><xref target="header.allow"/></c>
736  <c>ETag</c> <c>&header-etag;</c>
737  <c>Location</c> <c><xref target="header.location"/></c>
738  <c>Proxy-Authenticate</c> <c>&header-proxy-authenticate;</c>
739  <c>Retry-After</c> <c><xref target="header.retry-after"/></c>
740  <c>Server</c> <c><xref target="header.server"/></c>
741  <c>Vary</c> <c>&header-vary;</c>
742  <c>WWW-Authenticate</c> <c>&header-www-authenticate;</c>
743</texttable>
744<t>
745   Response-header field names can be extended reliably only in
746   combination with a change in the protocol version. However, new or
747   experimental header fields &MAY; be given the semantics of response-header
748   fields if all parties in the communication recognize them to
749   be response-header fields.
750</t>
751</section>
752
753<section title="Representation" anchor="representation">
754<t>
755   Request and Response messages &MAY; transfer a representation if not otherwise
756   restricted by the request method or response status code. A representation
757   consists of metadata (representation header fields) and data (representation
758   body).  When a complete or partial representation is enclosed in an HTTP message,
759   it is referred to as the payload of the message. HTTP representations
760   are defined in &payload;.
761</t>
762<t>
763   A representation body is only present in a message when a message-body is
764   present, as described in &message-body;. The representation body is obtained
765   from the message-body by decoding any Transfer-Encoding that might
766   have been applied to ensure safe and proper transfer of the message.
767</t>
768
769<section title="Identifying the Resource Associated with a Representation" anchor="identifying.response.associated.with.representation">
770<t>
771   It is sometimes necessary to determine an identifier for the resource
772   associated with a representation.
773</t>
774<t>
775   An HTTP request representation, when present, is always associated with an
776   anonymous (i.e., unidentified) resource.
777</t>
778<t>
779   In the common case, an HTTP response is a representation of the target
780   resource (see &effective-request-uri;). However, this is not always the
781   case. To determine the URI of the resource a response is associated with,
782   the following rules are used (with the first applicable one being selected):
783</t>
784<t><list style="numbers">
785   <t>If the response status code is 200 or 203 and the request method was GET,
786   the response payload is a representation of the target resource.</t>
787   <t>If the response status code is 204, 206, or 304 and the request method was GET
788   or HEAD, the response payload is a partial representation of the target
789   resource (see &combining-responses;).</t>
790   <t>If the response has a Content-Location header field, and that URI is the same
791   as the effective request URI, the response payload is a representation of the
792   target resource.</t>
793   <t>If the response has a Content-Location header field, and that URI is not the
794   same as the effective request URI, then the response asserts that its
795   payload is a representation of the resource identified by the
796   Content-Location URI. However, such an assertion cannot be trusted unless
797   it can be verified by other means (not defined by HTTP).</t>
798   <t>Otherwise, the response is a representation of an anonymous (i.e.,
799   unidentified) resource.</t>
800</list></t>
801<t>
802  <cref anchor="TODO-req-uri">
803   The comparison function is going to have to be defined somewhere,
804   because we already need to compare URIs for things like cache invalidation.</cref>
805</t>
806</section>
807
808</section>
809
810
811<section title="Method Definitions" anchor="method.definitions">
812<t>
813   The set of common methods for HTTP/1.1 is defined below. Although
814   this set can be expanded, additional methods cannot be assumed to
815   share the same semantics for separately extended clients and servers.
816</t>
817
818<section title="Safe and Idempotent Methods" anchor="safe.and.idempotent">
819
820<section title="Safe Methods" anchor="safe.methods">
821<iref item="Safe Methods" primary="true"/>
822<t>
823   Implementors need to be aware that the software represents the user in
824   their interactions over the Internet, and need to allow
825   the user to be aware of any actions they take which might have an
826   unexpected significance to themselves or others.
827</t>
828<t>
829   In particular, the convention has been established that the GET, HEAD,
830   OPTIONS, and TRACE methods &SHOULD-NOT; have the significance of taking an action
831   other than retrieval. These methods ought to be considered "<x:dfn anchor="safe">safe</x:dfn>".
832   This allows user agents to represent other methods, such as POST, PUT
833   and DELETE, in a special way, so that the user is made aware of the
834   fact that a possibly unsafe action is being requested.
835</t>
836<t>
837   Naturally, it is not possible to ensure that the server does not
838   generate side-effects as a result of performing a GET request; in
839   fact, some dynamic resources consider that a feature. The important
840   distinction here is that the user did not request the side-effects,
841   so therefore cannot be held accountable for them.
842</t>
843</section>
844
845<section title="Idempotent Methods" anchor="idempotent.methods">
846<iref item="Idempotent Methods" primary="true"/>
847<t>
848   Methods can also have the property of "idempotence" in that, aside
849   from error or expiration issues, the intended effect of multiple
850   identical requests is the same as for a single request.
851   The methods PUT, DELETE, and all safe methods are idempotent.
852   It is important to note that idempotence refers only to changes
853   requested by the client: a server is free to change its state due
854   to multiple requests for the purpose of tracking those requests,
855   versioning of results, etc.
856</t>
857</section>
858</section>
859
860<section title="OPTIONS" anchor="OPTIONS">
861  <rdf:Description>
862    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
863  </rdf:Description>
864  <iref primary="true" item="OPTIONS method" x:for-anchor=""/>
865  <iref primary="true" item="Methods" subitem="OPTIONS" x:for-anchor=""/>
866<t>
867   The OPTIONS method represents a request for information about the
868   communication options available on the request/response chain
869   identified by the effective request URI. This method allows the client to
870   determine the options and/or requirements associated with a resource,
871   or the capabilities of a server, without implying a resource action
872   or initiating a resource retrieval.
873</t>
874<t>
875   Responses to this method are not cacheable.
876</t>
877<t>
878   If the OPTIONS request includes a message-body (as indicated by the
879   presence of Content-Length or Transfer-Encoding), then the media type
880   &MUST; be indicated by a Content-Type field. Although this
881   specification does not define any use for such a body, future
882   extensions to HTTP might use the OPTIONS body to make more detailed
883   queries on the server.
884</t>
885<t>
886   If the request-target is an asterisk ("*"), the OPTIONS request is
887   intended to apply to the server in general rather than to a specific
888   resource. Since a server's communication options typically depend on
889   the resource, the "*" request is only useful as a "ping" or "no-op"
890   type of method; it does nothing beyond allowing the client to test
891   the capabilities of the server. For example, this can be used to test
892   a proxy for HTTP/1.1 compliance (or lack thereof).
893</t>
894<t>
895   If the request-target is not an asterisk, the OPTIONS request applies
896   only to the options that are available when communicating with that
897   resource.
898</t>
899<t>
900   A 200 response &SHOULD; include any header fields that indicate
901   optional features implemented by the server and applicable to that
902   resource (e.g., Allow), possibly including extensions not defined by
903   this specification. The response body, if any, &SHOULD; also include
904   information about the communication options. The format for such a
905   body is not defined by this specification, but might be defined by
906   future extensions to HTTP. Content negotiation &MAY; be used to select
907   the appropriate response format. If no response body is included, the
908   response &MUST; include a Content-Length field with a field-value of
909   "0".
910</t>
911<t>
912   The Max-Forwards request-header field &MAY; be used to target a
913   specific proxy in the request chain (see <xref target="header.max-forwards"/>).
914   If no Max-Forwards field is present in the request, then the forwarded
915   request &MUST-NOT; include a Max-Forwards field.
916</t>
917</section>
918
919<section title="GET" anchor="GET">
920  <rdf:Description>
921    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
922  </rdf:Description>
923  <iref primary="true" item="GET method" x:for-anchor=""/>
924  <iref primary="true" item="Methods" subitem="GET" x:for-anchor=""/>
925<t>
926   The GET method means retrieve whatever information (in the form of a
927   representation) currently corresponds to the target resource.
928</t>
929<t>   
930   If the target resource is a data-producing process, it is the
931   produced data which shall be returned as the representation in the response and not
932   the source text of the process, unless that text happens to be the output of
933   the process.
934</t>
935<t>
936   The semantics of the GET method change to a "conditional GET" if the
937   request message includes an If-Modified-Since, If-Unmodified-Since,
938   If-Match, If-None-Match, or If-Range header field. A conditional GET
939   method requests that the representation be transferred only under the
940   circumstances described by the conditional header field(s). The
941   conditional GET method is intended to reduce unnecessary network
942   usage by allowing cached representations to be refreshed without requiring
943   multiple requests or transferring data already held by the client.
944</t>
945<t>
946   The semantics of the GET method change to a "partial GET" if the
947   request message includes a Range header field. A partial GET requests
948   that only part of the representation be transferred, as described in &header-range;.
949   The partial GET method is intended to reduce unnecessary
950   network usage by allowing partially-retrieved representations to be
951   completed without transferring data already held by the client.
952</t>
953<t>
954   The response to a GET request is cacheable and &MAY; be used to satisfy
955   subsequent GET and HEAD requests (see &caching;).
956</t>
957<t>
958   See <xref target="encoding.sensitive.information.in.uris"/> for security considerations when used for forms.
959</t>
960</section>
961
962<section title="HEAD" anchor="HEAD">
963  <rdf:Description>
964    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
965  </rdf:Description>
966  <iref primary="true" item="HEAD method" x:for-anchor=""/>
967  <iref primary="true" item="Methods" subitem="HEAD" x:for-anchor=""/>
968<t>
969   The HEAD method is identical to GET except that the server &MUST-NOT;
970   return a message-body in the response. The metadata contained
971   in the HTTP header fields in response to a HEAD request &SHOULD; be identical
972   to the information sent in response to a GET request. This method can
973   be used for obtaining metadata about the representation implied by the
974   request without transferring the representation body. This method is
975   often used for testing hypertext links for validity, accessibility,
976   and recent modification.
977</t>
978<t>
979   The response to a HEAD request is cacheable and &MAY; be used to satisfy
980   a subsequent HEAD request; see &caching;. It also &MAY; be used to update a previously cached
981   representation from that resource; if the new field values
982   indicate that the cached representation differs from the current representation (as
983   would be indicated by a change in Content-Length, Content-MD5, ETag
984   or Last-Modified), then the cache &MUST; treat the cache entry as
985   stale.
986</t>
987</section>
988
989<section title="POST" anchor="POST">
990  <iref primary="true" item="POST method" x:for-anchor=""/>
991  <iref primary="true" item="Methods" subitem="POST" x:for-anchor=""/>
992<t>
993   The POST method is used to request that the origin server accept the
994   representation enclosed in the request as data to be processed by the
995   target resource. POST is designed to allow a uniform method to cover the
996   following functions:
997  <list style="symbols">
998    <t>
999      Annotation of existing resources;
1000    </t>
1001    <t>
1002        Posting a message to a bulletin board, newsgroup, mailing list,
1003        or similar group of articles;
1004    </t>
1005    <t>
1006        Providing a block of data, such as the result of submitting a
1007        form, to a data-handling process;
1008    </t>
1009    <t>
1010        Extending a database through an append operation.
1011    </t>
1012  </list>
1013</t>
1014<t>
1015   The actual function performed by the POST method is determined by the
1016   server and is usually dependent on the effective request URI.
1017</t>
1018<t>
1019   The action performed by the POST method might not result in a
1020   resource that can be identified by a URI. In this case, either 200
1021   (OK) or 204 (No Content) is the appropriate response status code,
1022   depending on whether or not the response includes a representation that
1023   describes the result.
1024</t>
1025<t>
1026   If a resource has been created on the origin server, the response
1027   &SHOULD; be 201 (Created) and contain a representation which describes the
1028   status of the request and refers to the new resource, and a Location
1029   header field (see <xref target="header.location"/>).
1030</t>
1031<t>
1032   Responses to POST requests are only cacheable when they
1033   include explicit freshness information (see &p6-explicit;). A
1034   cached POST response with a Content-Location header field
1035   (see &header-content-location;) whose value is the effective
1036   Request URI &MAY; be used to satisfy subsequent GET and HEAD requests.
1037</t>
1038<t>
1039   Note that POST caching is not widely implemented.
1040   However, the 303 (See Other) response can be used to direct the
1041   user agent to retrieve a cacheable resource.
1042</t>
1043</section>
1044
1045<section title="PUT" anchor="PUT">
1046  <iref primary="true" item="PUT method" x:for-anchor=""/>
1047  <iref primary="true" item="Methods" subitem="PUT" x:for-anchor=""/>
1048<t>
1049   The PUT method requests that the enclosed representation be stored at the
1050   effective request URI. If the effective request URI refers to an already
1051   existing resource, the enclosed representation &SHOULD; be considered a
1052   modified version of the one residing on the origin server. Otherwise, if the
1053   effective request URI does not point to an existing resource, and that URI is
1054   capable of being defined as a new resource by the requesting user
1055   agent, the origin server can create the resource with that URI.
1056</t>
1057<t>   
1058   If a new resource is created at the effective request URI, the origin
1059   server &MUST; inform the user agent
1060   via the 201 (Created) response. If an existing resource is modified,
1061   either the 200 (OK) or 204 (No Content) response codes &SHOULD; be sent
1062   to indicate successful completion of the request.
1063</t>
1064<t>   
1065   If the target resource could not be created or modified, an appropriate
1066   error response &SHOULD; be given that reflects the nature of the problem.
1067   The recipient of the representation &MUST-NOT; ignore any Content-*
1068   header fields (headers starting with the prefix "Content-") that it does
1069   not understand or implement
1070   and &MUST; return a 501 (Not Implemented) response in such cases.
1071</t>
1072<t>
1073   Responses to the PUT method are not cacheable. If a PUT request passes
1074   through a cache that has one or more stored responses for the effective
1075   request URI, those stored responses will be invalidated (see
1076   &p6-invalid;).
1077</t>
1078<t>
1079   The fundamental difference between the POST and PUT requests is
1080   reflected in the different meaning of the effective request URI. The URI in a
1081   POST request identifies the resource that will handle the enclosed
1082   representation. That resource might be a data-accepting process, a gateway to
1083   some other protocol, or a document that accepts annotations.
1084   In contrast, the URI in a PUT request identifies the resource for
1085   which enclosed representation is a new or replacement value; the
1086   user agent knows what URI is intended and the server &MUST-NOT; attempt
1087   to apply the request to some other resource.
1088   If the server desires that the request be applied to a different URI,
1089   it &MUST; send a 301 (Moved Permanently) response; the user agent &MAY;
1090   then make its own decision regarding whether or not to redirect the
1091   request.
1092</t>
1093<t>
1094   A single resource &MAY; be identified by many different URIs. For
1095   example, an article might have a URI for identifying "the current
1096   version" which is separate from the URI identifying each particular
1097   version. In this case, a PUT request on a general URI might result in
1098   several other URIs being defined by the origin server.
1099</t>
1100<t>
1101   HTTP/1.1 does not define how a PUT method affects the state of an
1102   origin server.
1103</t>
1104<t>
1105   Header fields in a PUT request that are recognized as representation
1106   metadata &SHOULD; be applied to the resource created or modified by
1107   the PUT.  Unrecognized header fields &SHOULD; be ignored.
1108</t>
1109</section>
1110
1111<section title="DELETE" anchor="DELETE">
1112  <iref primary="true" item="DELETE method" x:for-anchor=""/>
1113  <iref primary="true" item="Methods" subitem="DELETE" x:for-anchor=""/>
1114<t>
1115   The DELETE method requests that the origin server delete the target
1116   resource. This method &MAY; be overridden by
1117   human intervention (or other means) on the origin server. The client cannot
1118   be guaranteed that the operation has been carried out, even if the
1119   status code returned from the origin server indicates that the action
1120   has been completed successfully. However, the server &SHOULD-NOT; 
1121   indicate success unless, at the time the response is given, it
1122   intends to delete the resource or move it to an inaccessible
1123   location.
1124</t>
1125<t>
1126   A successful response &SHOULD; be 200 (OK) if the response includes an
1127   representation describing the status, 202 (Accepted) if the action has not
1128   yet been enacted, or 204 (No Content) if the action has been enacted
1129   but the response does not include a representation.
1130</t>
1131<t>
1132   Responses to the DELETE method are not cacheable. If a DELETE request
1133   passes through a cache that has one or more stored responses for the
1134   effective request URI, those stored responses will be invalidated (see
1135   &p6-invalid;).
1136</t>
1137</section>
1138
1139<section title="TRACE" anchor="TRACE">
1140  <rdf:Description>
1141    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
1142  </rdf:Description>
1143  <iref primary="true" item="TRACE method" x:for-anchor=""/>
1144  <iref primary="true" item="Methods" subitem="TRACE" x:for-anchor=""/>
1145<t>
1146   The TRACE method is used to invoke a remote, application-layer loop-back
1147   of the request message. The final recipient of the request
1148   &SHOULD; reflect the message received back to the client as the
1149   message-body of a 200 (OK) response. The final recipient is either the
1150   origin server or the first proxy or gateway to receive a Max-Forwards
1151   value of zero (0) in the request (see <xref target="header.max-forwards"/>).
1152   A TRACE request &MUST-NOT; include a message-body.
1153</t>
1154<t>
1155   TRACE allows the client to see what is being received at the other
1156   end of the request chain and use that data for testing or diagnostic
1157   information. The value of the Via header field (&header-via;) is of
1158   particular interest, since it acts as a trace of the request chain.
1159   Use of the Max-Forwards header field allows the client to limit the
1160   length of the request chain, which is useful for testing a chain of
1161   proxies forwarding messages in an infinite loop.
1162</t>
1163<t>
1164   If the request is valid, the response &SHOULD; have a Content-Type of
1165   "message/http" (see &media-type-message-http;) and contain a message-body
1166   that encloses a copy of the entire request message.
1167   Responses to the TRACE method are not cacheable.
1168</t>
1169</section>
1170
1171<section title="CONNECT" anchor="CONNECT">
1172  <iref primary="true" item="CONNECT method" x:for-anchor=""/>
1173  <iref primary="true" item="Methods" subitem="CONNECT" x:for-anchor=""/>
1174<t>
1175   The CONNECT method is used with a proxy to dynamically switch
1176   the connection to a tunnel.
1177</t>
1178<t>
1179   When using CONNECT, the request-target &MUST; be use the authority form
1180   (&request-target;); i.e., the host name and port number destination of the
1181   requested connection separated by a colon:
1182</t>
1183<figure><artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
1184CONNECT server.example.com:80 HTTP/1.1
1185Host: server.example.com:80
1186
1187</artwork></figure>
1188<t>
1189   Other HTTP mechanisms can be used normally with the CONNECT method &mdash;
1190   except end-to-end protocol Upgrade requests, since the
1191   tunnel must be established first.
1192</t>
1193<t>
1194   For example, proxy authentication might be used to establish the
1195   authority to create a tunnel:
1196</t>
1197<figure><artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
1198CONNECT server.example.com:80 HTTP/1.1
1199Host: server.example.com:80
1200Proxy-Authorization: basic aGVsbG86d29ybGQ=
1201
1202</artwork></figure>
1203<t>
1204   Like any other pipelined HTTP/1.1 request, data to be tunnel may be
1205   sent immediately after the blank line. The usual caveats also apply:
1206   data may be discarded if the eventual response is negative, and the
1207   connection may be reset with no response if more than one TCP segment
1208   is outstanding.
1209</t>
1210
1211<section title="Establishing a Tunnel with CONNECT">
1212<t>
1213   Any successful (2xx) response to a CONNECT request indicates that the
1214   proxy has established a connection to the requested host and port,
1215   and has switched to tunneling the current connection to that server
1216   connection.
1217</t>
1218<t>
1219   It may be the case that the proxy itself can only reach the requested
1220   origin server through another proxy.  In this case, the first proxy
1221   &SHOULD; make a CONNECT request of that next proxy, requesting a tunnel
1222   to the authority.  A proxy &MUST-NOT; respond with any 2xx status code
1223   unless it has either a direct or tunnel connection established to the
1224   authority.
1225</t>
1226<t>
1227   An origin server which receives a CONNECT request for itself &MAY;
1228   respond with a 2xx status code to indicate that a connection is
1229   established.
1230</t>
1231<t>
1232   If at any point either one of the peers gets disconnected, any
1233   outstanding data that came from that peer will be passed to the other
1234   one, and after that also the other connection will be terminated by
1235   the proxy. If there is outstanding data to that peer undelivered,
1236   that data will be discarded.
1237</t>
1238
1239</section>
1240</section>
1241</section>
1242
1243
1244<section title="Status Code Definitions" anchor="status.codes">
1245<t>
1246   Each Status-Code is described below, including any metadata required
1247   in the response.
1248</t>
1249
1250<section title="Informational 1xx" anchor="status.1xx">
1251<t>
1252   This class of status code indicates a provisional response,
1253   consisting only of the Status-Line and optional header fields, and is
1254   terminated by an empty line. There are no required header fields for this
1255   class of status code. Since HTTP/1.0 did not define any 1xx status
1256   codes, servers &MUST-NOT; send a 1xx response to an HTTP/1.0 client
1257   except under experimental conditions.
1258</t>
1259<t>
1260   A client &MUST; be prepared to accept one or more 1xx status responses
1261   prior to a regular response, even if the client does not expect a 100
1262   (Continue) status message. Unexpected 1xx status responses &MAY; be
1263   ignored by a user agent.
1264</t>
1265<t>
1266   Proxies &MUST; forward 1xx responses, unless the connection between the
1267   proxy and its client has been closed, or unless the proxy itself
1268   requested the generation of the 1xx response. (For example, if a
1269   proxy adds a "Expect: 100-continue" field when it forwards a request,
1270   then it need not forward the corresponding 100 (Continue)
1271   response(s).)
1272</t>
1273
1274<section title="100 Continue" anchor="status.100">
1275  <iref primary="true" item="100 Continue (status code)" x:for-anchor=""/>
1276  <iref primary="true" item="Status Codes" subitem="100 Continue" x:for-anchor=""/>
1277<t>
1278   The client &SHOULD; continue with its request. This interim response is
1279   used to inform the client that the initial part of the request has
1280   been received and has not yet been rejected by the server. The client
1281   &SHOULD; continue by sending the remainder of the request or, if the
1282   request has already been completed, ignore this response. The server
1283   &MUST; send a final response after the request has been completed. See
1284   &use100; for detailed discussion of the use and handling of this
1285   status code.
1286</t>
1287</section>
1288
1289<section title="101 Switching Protocols" anchor="status.101">
1290  <iref primary="true" item="101 Switching Protocols (status code)" x:for-anchor=""/>
1291  <iref primary="true" item="Status Codes" subitem="101 Switching Protocols" x:for-anchor=""/>
1292<t>
1293   The server understands and is willing to comply with the client's
1294   request, via the Upgrade message header field (&header-upgrade;), for a
1295   change in the application protocol being used on this connection. The
1296   server will switch protocols to those defined by the response's
1297   Upgrade header field immediately after the empty line which
1298   terminates the 101 response.
1299</t>
1300<t>
1301   The protocol &SHOULD; be switched only when it is advantageous to do
1302   so. For example, switching to a newer version of HTTP is advantageous
1303   over older versions, and switching to a real-time, synchronous
1304   protocol might be advantageous when delivering resources that use
1305   such features.
1306</t>
1307</section>
1308</section>
1309
1310<section title="Successful 2xx" anchor="status.2xx">
1311<t>
1312   This class of status code indicates that the client's request was
1313   successfully received, understood, and accepted.
1314</t>
1315
1316<section title="200 OK" anchor="status.200">
1317  <iref primary="true" item="200 OK (status code)" x:for-anchor=""/>
1318  <iref primary="true" item="Status Codes" subitem="200 OK" x:for-anchor=""/>
1319<t>
1320   The request has succeeded. The payload returned with the response
1321   is dependent on the method used in the request, for example:
1322  <list style="hanging">
1323    <t hangText="GET">
1324          a representation of the target resource is sent in the response;
1325    </t>
1326    <t hangText="HEAD">
1327          the same representation as GET, except without the message-body;
1328    </t>
1329    <t hangText="POST">
1330      a representation describing or containing the result of the action;
1331    </t>
1332    <t hangText="TRACE">
1333      a representation containing the request message as received by the
1334      end server.
1335    </t>
1336  </list>
1337</t>
1338<t>
1339   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1340   freshness for 200 responses.
1341</t>
1342</section>
1343
1344<section title="201 Created" anchor="status.201">
1345  <iref primary="true" item="201 Created (status code)" x:for-anchor=""/>
1346  <iref primary="true" item="Status Codes" subitem="201 Created" x:for-anchor=""/>
1347<t>
1348   The request has been fulfilled and has resulted in a new resource being
1349   created. The newly created resource can be referenced by the URI(s)
1350   returned in the payload of the response, with the most specific URI
1351   for the resource given by a Location header field. The response
1352   &SHOULD; include a payload containing a list of resource
1353   characteristics and location(s) from which the user or user agent can
1354   choose the one most appropriate. The payload format is specified by
1355   the media type given in the Content-Type header field. The origin
1356   server &MUST; create the resource before returning the 201 status code.
1357   If the action cannot be carried out immediately, the server &SHOULD;
1358   respond with 202 (Accepted) response instead.
1359</t>
1360<t>
1361   A 201 response &MAY; contain an ETag response header field indicating
1362   the current value of the entity-tag for the representation of the resource
1363   just created (see &header-etag;).
1364</t>
1365</section>
1366
1367<section title="202 Accepted" anchor="status.202">
1368  <iref primary="true" item="202 Accepted (status code)" x:for-anchor=""/>
1369  <iref primary="true" item="Status Codes" subitem="202 Accepted" x:for-anchor=""/>
1370<t>
1371   The request has been accepted for processing, but the processing has
1372   not been completed.  The request might or might not eventually be
1373   acted upon, as it might be disallowed when processing actually takes
1374   place. There is no facility for re-sending a status code from an
1375   asynchronous operation such as this.
1376</t>
1377<t>
1378   The 202 response is intentionally non-committal. Its purpose is to
1379   allow a server to accept a request for some other process (perhaps a
1380   batch-oriented process that is only run once per day) without
1381   requiring that the user agent's connection to the server persist
1382   until the process is completed. The representation returned with this
1383   response &SHOULD; include an indication of the request's current status
1384   and either a pointer to a status monitor or some estimate of when the
1385   user can expect the request to be fulfilled.
1386</t>
1387</section>
1388
1389<section title="203 Non-Authoritative Information" anchor="status.203">
1390  <iref primary="true" item="203 Non-Authoritative Information (status code)" x:for-anchor=""/>
1391  <iref primary="true" item="Status Codes" subitem="203 Non-Authoritative Information" x:for-anchor=""/>
1392<t>
1393   The returned metadata in the header fields is not the
1394   definitive set as available from the origin server, but is gathered
1395   from a local or a third-party copy. The set presented &MAY; be a subset
1396   or superset of the original version. For example, including local
1397   annotation information about the resource might result in a superset
1398   of the metadata known by the origin server. Use of this
1399   response code is not required and is only appropriate when the
1400   response would otherwise be 200 (OK).
1401</t>
1402<t>
1403   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1404   freshness for 203 responses.
1405</t>
1406
1407</section>
1408
1409<section title="204 No Content" anchor="status.204">
1410  <iref primary="true" item="204 No Content (status code)" x:for-anchor=""/>
1411  <iref primary="true" item="Status Codes" subitem="204 No Content" x:for-anchor=""/>
1412<t>
1413   The server has successfully fulfilled the request, but there is no
1414   additional content to return in the response payload body.  The
1415   resource metadata and representation metadata in the response message's
1416   header fields refer to the target resource
1417   and its current representation, respectively, after the requested action.
1418   For example, if a 204 status code is received in response to a PUT
1419   and the response contains an ETag header field, then the value of
1420   that field is the current entity-tag for the representation that
1421   was successfully PUT.
1422</t>
1423<t>
1424   If the client is a user agent, it &SHOULD-NOT; change its document view
1425   from that which caused the request to be sent. This response is
1426   primarily intended to allow input for actions to take place without
1427   causing a change to the user agent's active document view, although
1428   any new or updated metadata &SHOULD; be applied to the document
1429   currently in the user agent's active view.
1430</t>
1431<t>
1432   The 204 response &MUST-NOT; include a message-body, and thus is always
1433   terminated by the first empty line after the header fields.
1434</t>
1435</section>
1436
1437<section title="205 Reset Content" anchor="status.205">
1438  <iref primary="true" item="205 Reset Content (status code)" x:for-anchor=""/>
1439  <iref primary="true" item="Status Codes" subitem="205 Reset Content" x:for-anchor=""/>
1440<t>
1441   The server has fulfilled the request and the user agent &SHOULD; reset
1442   the document view which caused the request to be sent. This response
1443   is primarily intended to allow input for actions to take place via
1444   user input, followed by a clearing of the form in which the input is
1445   given so that the user can easily initiate another input action.
1446</t>
1447<t>   
1448   The message-body included with the response &MUST; be empty. Note that
1449   receivers still need to parse the response according to the algorithm defined
1450   in &message-body;.
1451</t>
1452</section>
1453
1454<section title="206 Partial Content" anchor="status.206">
1455  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
1456  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
1457  <rdf:Description>
1458    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1459  </rdf:Description>
1460<t>
1461   The server has fulfilled the partial GET request for the resource
1462   and the enclosed payload is a partial representation as defined in &status-206;.
1463</t>
1464<t>
1465   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1466   freshness for 206 responses.
1467</t>
1468</section>
1469</section>
1470
1471<section title="Redirection 3xx" anchor="status.3xx">
1472<t>
1473   This class of status code indicates that further action needs to be
1474   taken by the user agent in order to fulfill the request.  The action
1475   required &MAY; be carried out by the user agent without interaction
1476   with the user if and only if the method used in the second request is
1477   known to be "safe", as defined in <xref target="safe.methods"/>.
1478   A client &SHOULD; detect infinite redirection loops, since such loops
1479   generate network traffic for each redirection.
1480</t>
1481<x:note>
1482  <t>
1483    <x:h>Note:</x:h> An earlier version of this specification recommended a
1484    maximum of five redirections (<xref target="RFC2068" x:fmt="," x:sec="10.3"/>).
1485    Content developers need to be aware that some clients might
1486    implement such a fixed limitation.
1487  </t>
1488</x:note>
1489
1490<section title="300 Multiple Choices" anchor="status.300">
1491  <iref primary="true" item="300 Multiple Choices (status code)" x:for-anchor=""/>
1492  <iref primary="true" item="Status Codes" subitem="300 Multiple Choices" x:for-anchor=""/>
1493<t>
1494   The target resource has more than one
1495   representation, each with its own specific location, and agent-driven
1496   negotiation information (&content-negotiation;) is being provided so that
1497   the user (or user agent) can select a preferred representation by
1498   redirecting its request to that location.
1499</t>
1500<t>
1501   Unless it was a HEAD request, the response &SHOULD; include a representation
1502   containing a list of representation metadata and location(s) from
1503   which the user or user agent can choose the one most appropriate. The
1504   data format is specified by the media type given in the Content-Type
1505   header field. Depending upon the format and the capabilities of
1506   the user agent, selection of the most appropriate choice &MAY; be
1507   performed automatically. However, this specification does not define
1508   any standard for such automatic selection.
1509</t>
1510<t>
1511   If the server has a preferred choice of representation, it &SHOULD;
1512   include the specific URI for that representation in the Location
1513   field; user agents &MAY; use the Location field value for automatic
1514   redirection.
1515</t>
1516<t>
1517   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1518   freshness for 300 responses.
1519</t>
1520
1521</section>
1522
1523<section title="301 Moved Permanently" anchor="status.301">
1524  <iref primary="true" item="301 Moved Permanently (status code)" x:for-anchor=""/>
1525  <iref primary="true" item="Status Codes" subitem="301 Moved Permanently" x:for-anchor=""/>
1526<t>
1527   The target resource has been assigned a new permanent URI and any
1528   future references to this resource &SHOULD; use one of the returned
1529   URIs.  Clients with link editing capabilities ought to automatically
1530   re-link references to the effective request URI to one or more of the new
1531   references returned by the server, where possible.
1532</t>
1533<t>
1534   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1535   freshness for 301 responses.
1536</t>
1537<t>
1538   The new permanent URI &SHOULD; be given by the Location field in the
1539   response. Unless the request method was HEAD, the representation of the
1540   response &SHOULD; contain a short hypertext note with a hyperlink to
1541   the new URI(s).
1542</t>
1543<t>
1544   If the 301 status code is received in response to a request method
1545   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1546   then the request &MAY; be automatically redirected by the user agent without
1547   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1548   request unless it can be confirmed by the user, since this might
1549   change the conditions under which the request was issued.
1550</t>
1551<x:note>
1552  <t>
1553    <x:h>Note:</x:h> When automatically redirecting a POST request after
1554    receiving a 301 status code, some existing HTTP/1.0 user agents
1555    will erroneously change it into a GET request.
1556  </t>
1557</x:note>
1558</section>
1559
1560<section title="302 Found" anchor="status.302">
1561  <iref primary="true" item="302 Found (status code)" x:for-anchor=""/>
1562  <iref primary="true" item="Status Codes" subitem="302 Found" x:for-anchor=""/>
1563<t>
1564   The target resource resides temporarily under a different URI.
1565   Since the redirection might be altered on occasion, the client &SHOULD;
1566   continue to use the effective request URI for future requests.
1567</t>
1568<t>
1569   The temporary URI &SHOULD; be given by the Location field in the
1570   response. Unless the request method was HEAD, the representation of the
1571   response &SHOULD; contain a short hypertext note with a hyperlink to
1572   the new URI(s).
1573</t>
1574<t>
1575   If the 302 status code is received in response to a request method
1576   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1577   then the request &MAY; be automatically redirected by the user agent without
1578   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1579   request unless it can be confirmed by the user, since this might
1580   change the conditions under which the request was issued.
1581</t>
1582<x:note>
1583  <t>
1584    <x:h>Note:</x:h> HTTP/1.0 (<xref target="RFC1945" x:fmt="," x:sec="9.3"/>)
1585    and the first version of HTTP/1.1 (<xref target="RFC2068" x:fmt="," x:sec ="10.3.3"/>)
1586    specify that the client is not allowed to change the method on the
1587    redirected request.  However, most existing user agent implementations
1588    treat 302 as if it were a 303 response, performing a GET on the Location
1589    field-value regardless of the original request method. Therefore, a
1590    previous version of this specification
1591    (<xref target="RFC2616" x:fmt="," x:sec="10.3.3"/>) has added the
1592    status codes
1593    <xref target="status.303" format="none">303</xref> and
1594    <xref target="status.307" format="none">307</xref> for servers that wish
1595    to make unambiguously clear which kind of reaction is expected of the
1596    client.
1597  </t>
1598</x:note>
1599</section>
1600
1601<section title="303 See Other" anchor="status.303">
1602  <iref primary="true" item="303 See Other (status code)" x:for-anchor=""/>
1603  <iref primary="true" item="Status Codes" subitem="303 See Other" x:for-anchor=""/>
1604<t>
1605   The server directs the user agent to a different resource, indicated
1606   by a URI in the Location header field, that provides an indirect
1607   response to the original request.  The user agent &MAY; perform a GET
1608   request on the URI in the Location field in order to obtain a
1609   representation corresponding to the response, be redirected again,
1610   or end with an error status.  The Location URI is not a substitute
1611   reference for the effective request URI.
1612</t>
1613<t>
1614   The 303 status code is generally applicable to any HTTP method.  It is
1615   primarily used to allow the output of a POST action to redirect
1616   the user agent to a selected resource, since doing so provides the
1617   information corresponding to the POST response in a form that
1618   can be separately identified, bookmarked, and cached independent
1619   of the original request.
1620</t>
1621<t>
1622   A 303 response to a GET request indicates that the requested
1623   resource does not have a representation of its own that can be
1624   transferred by the server over HTTP.  The Location URI indicates a
1625   resource that is descriptive of the target resource, such that the
1626   follow-on representation might be useful to recipients without
1627   implying that it adequately represents the target resource.
1628   Note that answers to the questions of what can be represented, what
1629   representations are adequate, and what might be a useful description
1630   are outside the scope of HTTP and thus entirely determined by the
1631   URI owner(s).
1632</t>
1633<t>
1634   Except for responses to a HEAD request, the representation of a 303
1635   response &SHOULD; contain a short hypertext note with a hyperlink
1636   to the Location URI.
1637</t>
1638</section>
1639
1640<section title="304 Not Modified" anchor="status.304">
1641  <iref primary="true" item="304 Not Modified (status code)" x:for-anchor=""/>
1642  <iref primary="true" item="Status Codes" subitem="304 Not Modified" x:for-anchor=""/>
1643  <rdf:Description>
1644    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1645  </rdf:Description>
1646<t>
1647   The response to the request has not been modified since the conditions
1648   indicated by the client's conditional GET request, as defined in &status-304;.
1649</t>
1650</section>
1651
1652<section title="305 Use Proxy" anchor="status.305">
1653  <iref primary="true" item="305 Use Proxy (status code)" x:for-anchor=""/>
1654  <iref primary="true" item="Status Codes" subitem="305 Use Proxy" x:for-anchor=""/>
1655<t>
1656   The 305 status code was defined in a previous version of this specification
1657   (see <xref target="changes.from.rfc.2616"/>), and is now deprecated.
1658</t>
1659</section>
1660
1661<section title="306 (Unused)" anchor="status.306">
1662  <iref primary="true" item="306 (Unused) (status code)" x:for-anchor=""/>
1663  <iref primary="true" item="Status Codes" subitem="306 (Unused)" x:for-anchor=""/>
1664<t>
1665   The 306 status code was used in a previous version of the
1666   specification, is no longer used, and the code is reserved.
1667</t>
1668</section>
1669
1670<section title="307 Temporary Redirect" anchor="status.307">
1671  <iref primary="true" item="307 Temporary Redirect (status code)" x:for-anchor=""/>
1672  <iref primary="true" item="Status Codes" subitem="307 Temporary Redirect" x:for-anchor=""/>
1673<t>
1674   The target resource resides temporarily under a different URI.
1675   Since the redirection can change over time, the client &SHOULD;
1676   continue to use the effective request URI for future requests.
1677</t>
1678<t>
1679   The temporary URI &SHOULD; be given by the Location field in the
1680   response. Unless the request method was HEAD, the representation of the
1681   response &SHOULD; contain a short hypertext note with a hyperlink to
1682   the new URI(s), since many pre-HTTP/1.1 user agents do not
1683   understand the 307 status code. Therefore, the note &SHOULD; contain the
1684   information necessary for a user to repeat the original request on
1685   the new URI.
1686</t>
1687<t>
1688   If the 307 status code is received in response to a request method
1689   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1690   then the request &MAY; be automatically redirected by the user agent without
1691   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1692   request unless it can be confirmed by the user, since this might
1693   change the conditions under which the request was issued.
1694</t>
1695</section>
1696</section>
1697
1698<section title="Client Error 4xx" anchor="status.4xx">
1699<t>
1700   The 4xx class of status code is intended for cases in which the
1701   client seems to have erred. Except when responding to a HEAD request,
1702   the server &SHOULD; include a representation containing an explanation of the
1703   error situation, and whether it is a temporary or permanent
1704   condition. These status codes are applicable to any request method.
1705   User agents &SHOULD; display any included representation to the user.
1706</t>
1707<t>
1708   If the client is sending data, a server implementation using TCP
1709   &SHOULD; be careful to ensure that the client acknowledges receipt of
1710   the packet(s) containing the response, before the server closes the
1711   input connection. If the client continues sending data to the server
1712   after the close, the server's TCP stack will send a reset packet to
1713   the client, which might erase the client's unacknowledged input buffers
1714   before they can be read and interpreted by the HTTP application.
1715</t>
1716
1717<section title="400 Bad Request" anchor="status.400">
1718  <iref primary="true" item="400 Bad Request (status code)" x:for-anchor=""/>
1719  <iref primary="true" item="Status Codes" subitem="400 Bad Request" x:for-anchor=""/>
1720<t>
1721   The request could not be understood by the server due to malformed
1722   syntax. The client &SHOULD-NOT; repeat the request without
1723   modifications.
1724</t>
1725</section>
1726
1727<section title="401 Unauthorized" anchor="status.401">
1728  <iref primary="true" item="401 Unauthorized (status code)" x:for-anchor=""/>
1729  <iref primary="true" item="Status Codes" subitem="401 Unauthorized" x:for-anchor=""/>
1730  <rdf:Description>
1731    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part7</redirects-to>
1732  </rdf:Description>
1733<t>
1734   The request requires user authentication (see &status-401;).
1735</t>
1736</section>
1737
1738<section title="402 Payment Required" anchor="status.402">
1739  <iref primary="true" item="402 Payment Required (status code)" x:for-anchor=""/>
1740  <iref primary="true" item="Status Codes" subitem="402 Payment Required" x:for-anchor=""/>
1741<t>
1742   This code is reserved for future use.
1743</t>
1744</section>
1745
1746<section title="403 Forbidden" anchor="status.403">
1747  <iref primary="true" item="403 Forbidden (status code)" x:for-anchor=""/>
1748  <iref primary="true" item="Status Codes" subitem="403 Forbidden" x:for-anchor=""/>
1749<t>
1750   The server understood the request, but is refusing to fulfill it.
1751   Authorization will not help and the request &SHOULD-NOT;  be repeated.
1752   If the request method was not HEAD and the server wishes to make
1753   public why the request has not been fulfilled, it &SHOULD; describe the
1754   reason for the refusal in the representation.  If the server does not wish to
1755   make this information available to the client, the status code 404
1756   (Not Found) can be used instead.
1757</t>
1758</section>
1759
1760<section title="404 Not Found" anchor="status.404">
1761  <iref primary="true" item="404 Not Found (status code)" x:for-anchor=""/>
1762  <iref primary="true" item="Status Codes" subitem="404 Not Found" x:for-anchor=""/>
1763<t>
1764   The server has not found anything matching the effective request URI. No
1765   indication is given of whether the condition is temporary or
1766   permanent. The 410 (Gone) status code &SHOULD; be used if the server
1767   knows, through some internally configurable mechanism, that an old
1768   resource is permanently unavailable and has no forwarding address.
1769   This status code is commonly used when the server does not wish to
1770   reveal exactly why the request has been refused, or when no other
1771   response is applicable.
1772</t>
1773</section>
1774
1775<section title="405 Method Not Allowed" anchor="status.405">
1776  <iref primary="true" item="405 Method Not Allowed (status code)" x:for-anchor=""/>
1777  <iref primary="true" item="Status Codes" subitem="405 Method Not Allowed" x:for-anchor=""/>
1778<t>
1779   The method specified in the Request-Line is not allowed for the target
1780   resource. The response &MUST; include an
1781   Allow header field containing a list of valid methods for the requested
1782   resource.
1783</t>
1784</section>
1785
1786<section title="406 Not Acceptable" anchor="status.406">
1787  <iref primary="true" item="406 Not Acceptable (status code)" x:for-anchor=""/>
1788  <iref primary="true" item="Status Codes" subitem="406 Not Acceptable" x:for-anchor=""/>
1789<t>
1790   The resource identified by the request is only capable of generating
1791   response representations which have content characteristics not acceptable
1792   according to the accept header fields sent in the request.
1793</t>
1794<t>
1795   Unless it was a HEAD request, the response &SHOULD; include a representation
1796   containing a list of available representation characteristics and location(s)
1797   from which the user or user agent can choose the one most
1798   appropriate. The data format is specified by the media type given
1799   in the Content-Type header field. Depending upon the format and the
1800   capabilities of the user agent, selection of the most appropriate
1801   choice &MAY; be performed automatically. However, this specification
1802   does not define any standard for such automatic selection.
1803</t>
1804<x:note>
1805  <t>
1806    <x:h>Note:</x:h> HTTP/1.1 servers are allowed to return responses which are
1807    not acceptable according to the accept header fields sent in the
1808    request. In some cases, this might even be preferable to sending a
1809    406 response. User agents are encouraged to inspect the header fields of
1810    an incoming response to determine if it is acceptable.
1811  </t>
1812</x:note>
1813<t>
1814   If the response could be unacceptable, a user agent &SHOULD;
1815   temporarily stop receipt of more data and query the user for a
1816   decision on further actions.
1817</t>
1818</section>
1819
1820<section title="407 Proxy Authentication Required" anchor="status.407">
1821  <iref primary="true" item="407 Proxy Authentication Required (status code)" x:for-anchor=""/>
1822  <iref primary="true" item="Status Codes" subitem="407 Proxy Authentication Required" x:for-anchor=""/>
1823<t>
1824   This code is similar to 401 (Unauthorized), but indicates that the
1825   client must first authenticate itself with the proxy (see &status-407;).
1826</t>
1827</section>
1828
1829<section title="408 Request Timeout" anchor="status.408">
1830  <iref primary="true" item="408 Request Timeout (status code)" x:for-anchor=""/>
1831  <iref primary="true" item="Status Codes" subitem="408 Request Timeout" x:for-anchor=""/>
1832<t>
1833   The client did not produce a request within the time that the server
1834   was prepared to wait. The client &MAY; repeat the request without
1835   modifications at any later time.
1836</t>
1837</section>
1838
1839<section title="409 Conflict" anchor="status.409">
1840  <iref primary="true" item="409 Conflict (status code)" x:for-anchor=""/>
1841  <iref primary="true" item="Status Codes" subitem="409 Conflict" x:for-anchor=""/>
1842<t>
1843   The request could not be completed due to a conflict with the current
1844   state of the resource. This code is only allowed in situations where
1845   it is expected that the user might be able to resolve the conflict
1846   and resubmit the request. The response body &SHOULD; include enough
1847   information for the user to recognize the source of the conflict.
1848   Ideally, the response representation would include enough information for the
1849   user or user agent to fix the problem; however, that might not be
1850   possible and is not required.
1851</t>
1852<t>
1853   Conflicts are most likely to occur in response to a PUT request. For
1854   example, if versioning were being used and the representation being PUT
1855   included changes to a resource which conflict with those made by an
1856   earlier (third-party) request, the server might use the 409 response
1857   to indicate that it can't complete the request. In this case, the
1858   response representation would likely contain a list of the differences
1859   between the two versions in a format defined by the response
1860   Content-Type.
1861</t>
1862</section>
1863
1864<section title="410 Gone" anchor="status.410">
1865  <iref primary="true" item="410 Gone (status code)" x:for-anchor=""/>
1866  <iref primary="true" item="Status Codes" subitem="410 Gone" x:for-anchor=""/>
1867<t>
1868   The target resource is no longer available at the server and no
1869   forwarding address is known. This condition is expected to be
1870   considered permanent. Clients with link editing capabilities &SHOULD;
1871   delete references to the effective request URI after user approval. If the
1872   server does not know, or has no facility to determine, whether or not
1873   the condition is permanent, the status code 404 (Not Found) &SHOULD; be
1874   used instead.
1875</t>
1876<t>
1877   The 410 response is primarily intended to assist the task of web
1878   maintenance by notifying the recipient that the resource is
1879   intentionally unavailable and that the server owners desire that
1880   remote links to that resource be removed. Such an event is common for
1881   limited-time, promotional services and for resources belonging to
1882   individuals no longer working at the server's site. It is not
1883   necessary to mark all permanently unavailable resources as "gone" or
1884   to keep the mark for any length of time &mdash; that is left to the
1885   discretion of the server owner.
1886</t>
1887<t>
1888   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine freshness
1889   for 410 responses.
1890</t>
1891
1892</section>
1893
1894<section title="411 Length Required" anchor="status.411">
1895  <iref primary="true" item="411 Length Required (status code)" x:for-anchor=""/>
1896  <iref primary="true" item="Status Codes" subitem="411 Length Required" x:for-anchor=""/>
1897<t>
1898   The server refuses to accept the request without a defined Content-Length.
1899   The client &MAY; repeat the request if it adds a valid
1900   Content-Length header field containing the length of the message-body
1901   in the request message.
1902</t>
1903</section>
1904
1905<section title="412 Precondition Failed" anchor="status.412">
1906  <iref primary="true" item="412 Precondition Failed (status code)" x:for-anchor=""/>
1907  <iref primary="true" item="Status Codes" subitem="412 Precondition Failed" x:for-anchor=""/>
1908  <rdf:Description>
1909    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1910  </rdf:Description>
1911<t>
1912   The precondition given in one or more of the request-header fields
1913   evaluated to false when it was tested on the server, as defined in
1914   &status-412;.
1915</t>
1916</section>
1917
1918<section title="413 Request Entity Too Large" anchor="status.413">
1919  <iref primary="true" item="413 Request Entity Too Large (status code)" x:for-anchor=""/>
1920  <iref primary="true" item="Status Codes" subitem="413 Request Entity Too Large" x:for-anchor=""/>
1921<t>
1922   The server is refusing to process a request because the request
1923   representation is larger than the server is willing or able to process. The
1924   server &MAY; close the connection to prevent the client from continuing
1925   the request.
1926</t>
1927<t>
1928   If the condition is temporary, the server &SHOULD; include a Retry-After
1929   header field to indicate that it is temporary and after what
1930   time the client &MAY; try again.
1931</t>
1932</section>
1933
1934<section title="414 URI Too Long" anchor="status.414">
1935  <iref primary="true" item="414 URI Too Long (status code)" x:for-anchor=""/>
1936  <iref primary="true" item="Status Codes" subitem="414 URI Too Long" x:for-anchor=""/>
1937<t>
1938   The server is refusing to service the request because the effective request URI
1939   is longer than the server is willing to interpret. This rare
1940   condition is only likely to occur when a client has improperly
1941   converted a POST request to a GET request with long query
1942   information, when the client has descended into a URI "black hole" of
1943   redirection (e.g., a redirected URI prefix that points to a suffix of
1944   itself), or when the server is under attack by a client attempting to
1945   exploit security holes present in some servers using fixed-length
1946   buffers for reading or manipulating the effective request URI.
1947</t>
1948</section>
1949
1950<section title="415 Unsupported Media Type" anchor="status.415">
1951  <iref primary="true" item="415 Unsupported Media Type (status code)" x:for-anchor=""/>
1952  <iref primary="true" item="Status Codes" subitem="415 Unsupported Media Type" x:for-anchor=""/>
1953<t>
1954   The server is refusing to service the request because the representation of
1955   the request is in a format not supported by the target resource
1956   for the requested method.
1957</t>
1958</section>
1959
1960<section title="416 Requested Range Not Satisfiable" anchor="status.416">
1961  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
1962  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
1963  <rdf:Description>
1964    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1965  </rdf:Description>
1966<t>
1967   The request included a Range request-header field (&header-range;) and none of
1968   the range-specifier values in this field overlap the current extent
1969   of the selected resource. See &status-416;.
1970</t>
1971</section>
1972
1973<section title="417 Expectation Failed" anchor="status.417">
1974  <iref primary="true" item="417 Expectation Failed (status code)" x:for-anchor=""/>
1975  <iref primary="true" item="Status Codes" subitem="417 Expectation Failed" x:for-anchor=""/>
1976<t>
1977   The expectation given in an Expect request-header field (see <xref target="header.expect"/>)
1978   could not be met by this server, or, if the server is a proxy,
1979   the server has unambiguous evidence that the request could not be met
1980   by the next-hop server.
1981</t>
1982</section>
1983
1984<section title="426 Upgrade Required" anchor="status.426">
1985  <iref primary="true" item="426 Upgrade Required (status code)" x:for-anchor=""/>
1986  <iref primary="true" item="Status Codes" subitem="426 Upgrade Required" x:for-anchor=""/>
1987<t>
1988   The request can not be completed without a prior protocol upgrade. This
1989   response &MUST; include an Upgrade header field (&header-upgrade;)
1990   specifying the required protocols.
1991</t>
1992<figure>
1993<preamble>Example:</preamble>
1994<artwork type="message/http; msgtype=&#34;request&#34;" x:indent-with="  ">
1995HTTP/1.1 426 Upgrade Required
1996Upgrade: HTTP/2.0
1997Connection: Upgrade
1998
1999</artwork></figure>
2000<t>
2001   The server &SHOULD; include a message body in the 426 response which
2002   indicates in human readable form the reason for the error and describes any
2003   alternative courses which may be available to the user.
2004</t>
2005</section>
2006</section>
2007
2008<section title="Server Error 5xx" anchor="status.5xx">
2009<t>
2010   Response status codes beginning with the digit "5" indicate cases in
2011   which the server is aware that it has erred or is incapable of
2012   performing the request. Except when responding to a HEAD request, the
2013   server &SHOULD; include a representation containing an explanation of the
2014   error situation, and whether it is a temporary or permanent
2015   condition. User agents &SHOULD; display any included representation to the
2016   user. These response codes are applicable to any request method.
2017</t>
2018
2019<section title="500 Internal Server Error" anchor="status.500">
2020  <iref primary="true" item="500 Internal Server Error (status code)" x:for-anchor=""/>
2021  <iref primary="true" item="Status Codes" subitem="500 Internal Server Error" x:for-anchor=""/>
2022<t>
2023   The server encountered an unexpected condition which prevented it
2024   from fulfilling the request.
2025</t>
2026</section>
2027
2028<section title="501 Not Implemented" anchor="status.501">
2029  <iref primary="true" item="501 Not Implemented (status code)" x:for-anchor=""/>
2030  <iref primary="true" item="Status Codes" subitem="501 Not Implemented" x:for-anchor=""/>
2031<t>
2032   The server does not support the functionality required to fulfill the
2033   request. This is the appropriate response when the server does not
2034   recognize the request method and is not capable of supporting it for
2035   any resource.
2036</t>
2037</section>
2038
2039<section title="502 Bad Gateway" anchor="status.502">
2040  <iref primary="true" item="502 Bad Gateway (status code)" x:for-anchor=""/>
2041  <iref primary="true" item="Status Codes" subitem="502 Bad Gateway" x:for-anchor=""/>
2042<t>
2043   The server, while acting as a gateway or proxy, received an invalid
2044   response from the upstream server it accessed in attempting to
2045   fulfill the request.
2046</t>
2047</section>
2048
2049<section title="503 Service Unavailable" anchor="status.503">
2050  <iref primary="true" item="503 Service Unavailable (status code)" x:for-anchor=""/>
2051  <iref primary="true" item="Status Codes" subitem="503 Service Unavailable" x:for-anchor=""/>
2052<t>
2053   The server is currently unable to handle the request due to a
2054   temporary overloading or maintenance of the server. The implication
2055   is that this is a temporary condition which will be alleviated after
2056   some delay. If known, the length of the delay &MAY; be indicated in a
2057   Retry-After header field. If no Retry-After is given, the client &SHOULD;
2058   handle the response as it would for a 500 response.
2059</t>
2060<x:note>
2061  <t>
2062    <x:h>Note:</x:h> The existence of the 503 status code does not imply that a
2063    server must use it when becoming overloaded. Some servers might wish
2064    to simply refuse the connection.
2065  </t>
2066</x:note>
2067</section>
2068
2069<section title="504 Gateway Timeout" anchor="status.504">
2070  <iref primary="true" item="504 Gateway Timeout (status code)" x:for-anchor=""/>
2071  <iref primary="true" item="Status Codes" subitem="504 Gateway Timeout" x:for-anchor=""/>
2072<t>
2073   The server, while acting as a gateway or proxy, did not receive a
2074   timely response from the upstream server specified by the URI (e.g.,
2075   HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed
2076   to access in attempting to complete the request.
2077</t>
2078<x:note>
2079  <t>
2080    <x:h>Note</x:h> to implementors: some deployed proxies are known to
2081    return 400 or 500 when DNS lookups time out.
2082  </t>
2083</x:note>
2084</section>
2085
2086<section title="505 HTTP Version Not Supported" anchor="status.505">
2087  <iref primary="true" item="505 HTTP Version Not Supported (status code)" x:for-anchor=""/>
2088  <iref primary="true" item="Status Codes" subitem="505 HTTP Version Not Supported" x:for-anchor=""/>
2089<t>
2090   The server does not support, or refuses to support, the protocol
2091   version that was used in the request message. The server is
2092   indicating that it is unable or unwilling to complete the request
2093   using the same major version as the client, as described in &http-version;,
2094   other than with this error message. The response &SHOULD; contain
2095   a representation describing why that version is not supported and what other
2096   protocols are supported by that server.
2097</t>
2098
2099</section>
2100</section>
2101</section>
2102
2103
2104<section title="Header Field Definitions" anchor="header.fields">
2105<t>
2106   This section defines the syntax and semantics of HTTP/1.1 header fields
2107   related to request and response semantics.
2108</t>
2109
2110<section title="Allow" anchor="header.allow">
2111  <iref primary="true" item="Allow header field" x:for-anchor=""/>
2112  <iref primary="true" item="Header Fields" subitem="Allow" x:for-anchor=""/>
2113  <x:anchor-alias value="Allow"/>
2114  <x:anchor-alias value="Allow-v"/>
2115<t>
2116   The "Allow" response-header field lists the set of methods advertised as
2117   supported by the target resource. The purpose of this field is strictly to
2118   inform the recipient of valid methods associated with the resource.
2119</t>
2120<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Allow"/><iref primary="true" item="Grammar" subitem="Allow-v"/>
2121  <x:ref>Allow</x:ref>   = "Allow" ":" <x:ref>OWS</x:ref> <x:ref>Allow-v</x:ref>
2122  <x:ref>Allow-v</x:ref> = #<x:ref>Method</x:ref>
2123</artwork></figure>
2124<t>
2125   Example of use:
2126</t>
2127<figure><artwork type="example">
2128  Allow: GET, HEAD, PUT
2129</artwork></figure>
2130<t>
2131   The actual set of allowed methods is defined by the origin server at the
2132   time of each request.
2133</t>
2134<t>
2135   A proxy &MUST-NOT; modify the Allow header field &mdash; it does not need to
2136   understand all the methods specified in order to handle them according to
2137   the generic message handling rules.
2138</t>
2139</section>
2140
2141<section title="Expect" anchor="header.expect">
2142  <iref primary="true" item="Expect header field" x:for-anchor=""/>
2143  <iref primary="true" item="Header Fields" subitem="Expect" x:for-anchor=""/>
2144  <x:anchor-alias value="Expect"/>
2145  <x:anchor-alias value="Expect-v"/>
2146  <x:anchor-alias value="expectation"/>
2147  <x:anchor-alias value="expectation-extension"/>
2148  <x:anchor-alias value="expect-params"/>
2149<t>
2150   The "Expect" request-header field is used to indicate that particular
2151   server behaviors are required by the client.
2152</t>
2153<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Expect"/><iref primary="true" item="Grammar" subitem="Expect-v"/><iref primary="true" item="Grammar" subitem="expectation"/><iref primary="true" item="Grammar" subitem="expectation-extension"/><iref primary="true" item="Grammar" subitem="expect-params"/>
2154  <x:ref>Expect</x:ref>       = "Expect" ":" <x:ref>OWS</x:ref> <x:ref>Expect-v</x:ref>
2155  <x:ref>Expect-v</x:ref>     = 1#<x:ref>expectation</x:ref>
2156 
2157  <x:ref>expectation</x:ref>  = "100-continue" / <x:ref>expectation-extension</x:ref>
2158  <x:ref>expectation-extension</x:ref> = <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> )
2159                           *<x:ref>expect-params</x:ref> ]
2160  <x:ref>expect-params</x:ref> = ";" <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> ) ]
2161</artwork></figure>
2162<t>
2163   A server that does not understand or is unable to comply with any of
2164   the expectation values in the Expect field of a request &MUST; respond
2165   with appropriate error status code. The server &MUST; respond with a 417
2166   (Expectation Failed) status code if any of the expectations cannot be met
2167   or, if there are other problems with the request, some other 4xx
2168   status code.
2169</t>
2170<t>
2171   This header field is defined with extensible syntax to allow for
2172   future extensions. If a server receives a request containing an
2173   Expect field that includes an expectation-extension that it does not
2174   support, it &MUST; respond with a 417 (Expectation Failed) status code.
2175</t>
2176<t>
2177   Comparison of expectation values is case-insensitive for unquoted
2178   tokens (including the 100-continue token), and is case-sensitive for
2179   quoted-string expectation-extensions.
2180</t>
2181<t>
2182   The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy &MUST;
2183   return a 417 (Expectation Failed) status code if it receives a request
2184   with an expectation that it cannot meet. However, the Expect
2185   request-header field itself is end-to-end; it &MUST; be forwarded if the
2186   request is forwarded.
2187</t>
2188<t>
2189   Many older HTTP/1.0 and HTTP/1.1 applications do not understand the
2190   Expect header field.
2191</t>
2192<t>
2193   See &use100; for the use of the 100 (Continue) status code.
2194</t>
2195</section>
2196
2197<section title="From" anchor="header.from">
2198  <iref primary="true" item="From header field" x:for-anchor=""/>
2199  <iref primary="true" item="Header Fields" subitem="From" x:for-anchor=""/>
2200  <x:anchor-alias value="From"/>
2201  <x:anchor-alias value="From-v"/>
2202  <x:anchor-alias value="mailbox"/>
2203<t>
2204   The "From" request-header field, if given, &SHOULD; contain an Internet
2205   e-mail address for the human user who controls the requesting user
2206   agent. The address &SHOULD; be machine-usable, as defined by "mailbox"
2207   in <xref x:sec="3.4" x:fmt="of" target="RFC5322"/>:
2208</t>
2209<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="From"/><iref primary="true" item="Grammar" subitem="From-v"/>
2210  <x:ref>From</x:ref>    = "From" ":" <x:ref>OWS</x:ref> <x:ref>From-v</x:ref>
2211  <x:ref>From-v</x:ref>  = <x:ref>mailbox</x:ref>
2212 
2213  <x:ref>mailbox</x:ref> = &lt;mailbox, defined in <xref x:sec="3.4" x:fmt="," target="RFC5322"/>&gt;
2214</artwork></figure>
2215<t>
2216   An example is:
2217</t>
2218<figure><artwork type="example">
2219  From: webmaster@example.org
2220</artwork></figure>
2221<t>
2222   This header field &MAY; be used for logging purposes and as a means for
2223   identifying the source of invalid or unwanted requests. It &SHOULD-NOT; 
2224   be used as an insecure form of access protection. The interpretation
2225   of this field is that the request is being performed on behalf of the
2226   person given, who accepts responsibility for the method performed. In
2227   particular, robot agents &SHOULD; include this header field so that the
2228   person responsible for running the robot can be contacted if problems
2229   occur on the receiving end.
2230</t>
2231<t>
2232   The Internet e-mail address in this field &MAY; be separate from the
2233   Internet host which issued the request. For example, when a request
2234   is passed through a proxy the original issuer's address &SHOULD; be
2235   used.
2236</t>
2237<t>
2238   The client &SHOULD-NOT;  send the From header field without the user's
2239   approval, as it might conflict with the user's privacy interests or
2240   their site's security policy. It is strongly recommended that the
2241   user be able to disable, enable, and modify the value of this field
2242   at any time prior to a request.
2243</t>
2244</section>
2245
2246<section title="Location" anchor="header.location">
2247  <iref primary="true" item="Location header field" x:for-anchor=""/>
2248  <iref primary="true" item="Header Fields" subitem="Location" x:for-anchor=""/>
2249  <x:anchor-alias value="Location"/>
2250  <x:anchor-alias value="Location-v"/>
2251<t>
2252   The "Location" response-header field is used to identify a newly created
2253   resource, or to redirect the recipient to a different location for
2254   completion of the request.
2255</t>
2256<t>
2257   For 201 (Created) responses, the Location is the URI of the new resource
2258   which was created by the request. For 3xx responses, the location &SHOULD;
2259   indicate the server's preferred URI for automatic redirection to the
2260   resource.
2261</t>
2262<t>
2263   The field value consists of a single URI-reference. When it has the form
2264   of a relative reference (<xref target="RFC3986" x:fmt="," x:sec="4.2"/>),
2265   the final value is computed by resolving it against the effective request
2266   URI (<xref target="RFC3986" x:fmt="," x:sec="5"/>).
2267</t>
2268<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Location"/><iref primary="true" item="Grammar" subitem="Location-v"/>
2269  <x:ref>Location</x:ref>       = "Location" ":" <x:ref>OWS</x:ref> <x:ref>Location-v</x:ref>
2270  <x:ref>Location-v</x:ref>     = <x:ref>URI-reference</x:ref>
2271</artwork></figure>
2272<figure>
2273<preamble>Examples are:</preamble><!--DO NOT DARE changing the vertical WSP below, it's necessary this way for xml2rfc-->
2274<artwork type="example">
2275  Location: http://www.example.org/pub/WWW/People.html#tim
2276</artwork></figure><figure><artwork type="example">  Location: /index.html
2277</artwork></figure>
2278<t>
2279   There are circumstances in which a fragment identifier in a Location URI
2280   would not be appropriate:
2281   <list style="symbols">
2282      <t>With a 201 Created response, because in this usage the Location header
2283      field specifies the URI for the entire created resource.</t>
2284      <t>With 305 Use Proxy.</t>
2285   </list>
2286</t>
2287<x:note>
2288  <t>
2289    <x:h>Note:</x:h> This specification does not define precedence rules
2290    for the case where the original URI, as navigated to by the user
2291    agent, and the Location header field value both contain fragment
2292    identifiers. Thus be aware that including fragment identifiers might
2293    inconvenience anyone relying on the semantics of the original URI's
2294    fragment identifier.
2295  </t>
2296</x:note>
2297<x:note>
2298  <t>
2299    <x:h>Note:</x:h> The Content-Location header field (&header-content-location;) differs
2300    from Location in that the Content-Location identifies the most specific
2301    resource corresponding to the enclosed representation.
2302    It is therefore possible for a response to contain header fields for
2303    both Location and Content-Location.
2304  </t>
2305</x:note>
2306</section>
2307
2308<section title="Max-Forwards" anchor="header.max-forwards">
2309  <iref primary="true" item="Max-Forwards header field" x:for-anchor=""/>
2310  <iref primary="true" item="Header Fields" subitem="Max-Forwards" x:for-anchor=""/>
2311  <x:anchor-alias value="Max-Forwards"/>
2312  <x:anchor-alias value="Max-Forwards-v"/>
2313<t>
2314   The "Max-Forwards" request-header field provides a mechanism with the
2315   TRACE (<xref target="TRACE"/>) and OPTIONS (<xref target="OPTIONS"/>)
2316   methods to limit the number of times that the request is forwarded by
2317   proxies or gateways. This can be useful when the client is attempting to
2318   trace a request which appears to be failing or looping in mid-chain.
2319</t>
2320<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Max-Forwards"/><iref primary="true" item="Grammar" subitem="Max-Forwards-v"/>
2321  <x:ref>Max-Forwards</x:ref>   = "Max-Forwards" ":" <x:ref>OWS</x:ref> <x:ref>Max-Forwards-v</x:ref>
2322  <x:ref>Max-Forwards-v</x:ref> = 1*<x:ref>DIGIT</x:ref>
2323</artwork></figure>
2324<t>
2325   The Max-Forwards value is a decimal integer indicating the remaining
2326   number of times this request message can be forwarded.
2327</t>
2328<t>
2329   Each proxy or gateway recipient of a TRACE or OPTIONS request
2330   containing a Max-Forwards header field &MUST; check and update its
2331   value prior to forwarding the request. If the received value is zero
2332   (0), the recipient &MUST-NOT; forward the request; instead, it &MUST;
2333   respond as the final recipient. If the received Max-Forwards value is
2334   greater than zero, then the forwarded message &MUST; contain an updated
2335   Max-Forwards field with a value decremented by one (1).
2336</t>
2337<t>
2338   The Max-Forwards header field &MAY; be ignored for all other methods.
2339</t>
2340</section>
2341
2342<section title="Referer" anchor="header.referer">
2343  <iref primary="true" item="Referer header field" x:for-anchor=""/>
2344  <iref primary="true" item="Header Fields" subitem="Referer" x:for-anchor=""/>
2345  <x:anchor-alias value="Referer"/>
2346  <x:anchor-alias value="Referer-v"/>
2347<t>
2348   The "Referer" [sic] request-header field allows the client to specify the
2349   URI of the resource from which the effective request URI was obtained (the
2350   "referrer", although the header field is misspelled.).
2351</t>
2352<t>
2353   The Referer header field allows servers to generate lists of back-links to
2354   resources for interest, logging, optimized caching, etc. It also allows
2355   obsolete or mistyped links to be traced for maintenance. Some servers use
2356   Referer as a means of controlling where they allow links from (so-called
2357   "deep linking"), but legitimate requests do not always
2358   contain a Referer header field.
2359</t>
2360<t>
2361   If the effective request URI was obtained from a source that does not have its own
2362   URI (e.g., input from the user keyboard), the Referer field &MUST; either be
2363   sent with the value "about:blank", or not be sent at all. Note that this
2364   requirement does not apply to sources with non-HTTP URIs (e.g., FTP).
2365</t>
2366<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Referer"/><iref primary="true" item="Grammar" subitem="Referer-v"/>
2367  <x:ref>Referer</x:ref>        = "Referer" ":" <x:ref>OWS</x:ref> <x:ref>Referer-v</x:ref>
2368  <x:ref>Referer-v</x:ref>      = <x:ref>absolute-URI</x:ref> / <x:ref>partial-URI</x:ref>
2369</artwork></figure>
2370<t>
2371   Example:
2372</t>
2373<figure><artwork type="example">
2374  Referer: http://www.example.org/hypertext/Overview.html
2375</artwork></figure>
2376<t>
2377   If the field value is a relative URI, it &SHOULD; be interpreted
2378   relative to the effective request URI. The URI &MUST-NOT; include a fragment. See
2379   <xref target="encoding.sensitive.information.in.uris"/> for security considerations.
2380</t>
2381</section>
2382
2383<section title="Retry-After" anchor="header.retry-after">
2384  <iref primary="true" item="Retry-After header field" x:for-anchor=""/>
2385  <iref primary="true" item="Header Fields" subitem="Retry-After" x:for-anchor=""/>
2386  <x:anchor-alias value="Retry-After"/>
2387  <x:anchor-alias value="Retry-After-v"/>
2388<t>
2389   The response-header "Retry-After" field can be used with a 503 (Service
2390   Unavailable) response to indicate how long the service is expected to
2391   be unavailable to the requesting client. This field &MAY; also be used
2392   with any 3xx (Redirection) response to indicate the minimum time the
2393   user-agent is asked wait before issuing the redirected request.
2394</t>
2395<t>
2396   The value of this field can be either an HTTP-date or an integer number
2397   of seconds (in decimal) after the time of the response.
2398</t>
2399<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Retry-After"/><iref primary="true" item="Grammar" subitem="Retry-After-v"/>
2400  <x:ref>Retry-After</x:ref>   = "Retry-After" ":" <x:ref>OWS</x:ref> <x:ref>Retry-After-v</x:ref>
2401  <x:ref>Retry-After-v</x:ref> = <x:ref>HTTP-date</x:ref> / <x:ref>delta-seconds</x:ref>
2402</artwork></figure>
2403<t anchor="rule.delta-seconds">
2404  <x:anchor-alias value="delta-seconds"/>
2405   Time spans are non-negative decimal integers, representing time in
2406   seconds.
2407</t>
2408<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="delta-seconds"/>
2409  <x:ref>delta-seconds</x:ref>  = 1*<x:ref>DIGIT</x:ref>
2410</artwork></figure>
2411<t>
2412   Two examples of its use are
2413</t>
2414<figure><artwork type="example">
2415  Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
2416  Retry-After: 120
2417</artwork></figure>
2418<t>
2419   In the latter example, the delay is 2 minutes.
2420</t>
2421</section>
2422
2423<section title="Server" anchor="header.server">
2424  <iref primary="true" item="Server header field" x:for-anchor=""/>
2425  <iref primary="true" item="Header Fields" subitem="Server" x:for-anchor=""/>
2426  <x:anchor-alias value="Server"/>
2427  <x:anchor-alias value="Server-v"/>
2428<t>
2429   The "Server" response-header field contains information about the
2430   software used by the origin server to handle the request.
2431</t>
2432<t>
2433   The field can contain multiple product tokens (&product-tokens;) and
2434   comments (&header-fields;) identifying the server and any significant
2435   subproducts. The product tokens are listed in order of their significance
2436   for identifying the application.
2437</t>
2438<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Server"/><iref primary="true" item="Grammar" subitem="Server-v"/>
2439  <x:ref>Server</x:ref>         = "Server" ":" <x:ref>OWS</x:ref> <x:ref>Server-v</x:ref>
2440  <x:ref>Server-v</x:ref>       = <x:ref>product</x:ref>
2441                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2442</artwork></figure>
2443<t>
2444   Example:
2445</t>
2446<figure><artwork type="example">
2447  Server: CERN/3.0 libwww/2.17
2448</artwork></figure>
2449<t>
2450   If the response is being forwarded through a proxy, the proxy
2451   application &MUST-NOT; modify the Server response-header field. Instead, it
2452   &MUST; include a Via field (as described in &header-via;).
2453</t>
2454<x:note>
2455  <t>
2456    <x:h>Note:</x:h> Revealing the specific software version of the server might
2457    allow the server machine to become more vulnerable to attacks
2458    against software that is known to contain security holes. Server
2459    implementors are encouraged to make this field a configurable
2460    option.
2461  </t>
2462</x:note>
2463</section>
2464
2465<section title="User-Agent" anchor="header.user-agent">
2466  <iref primary="true" item="User-Agent header field" x:for-anchor=""/>
2467  <iref primary="true" item="Header Fields" subitem="User-Agent" x:for-anchor=""/>
2468  <x:anchor-alias value="User-Agent"/>
2469  <x:anchor-alias value="User-Agent-v"/>
2470<t>
2471   The "User-Agent" request-header field contains information about the user
2472   agent originating the request. User agents &SHOULD; include this field with
2473   requests.
2474</t>
2475<t>
2476   Typically, it is used for statistical purposes, the tracing of protocol
2477   violations, and tailoring responses to avoid particular user agent
2478   limitations.
2479</t>
2480<t>
2481   The field can contain multiple product tokens (&product-tokens;)
2482   and comments (&header-fields;) identifying the agent and its
2483   significant subproducts. By convention, the product tokens are listed in
2484   order of their significance for identifying the application.
2485</t>
2486<t>
2487   Because this field is usually sent on every request a user agent makes,
2488   implementations are encouraged not to include needlessly fine-grained
2489   detail, and to limit (or even prohibit) the addition of subproducts by third
2490   parties. Overly long and detailed User-Agent field values make requests
2491   larger and can also be used to identify ("fingerprint") the user against
2492   their wishes.
2493</t>
2494<t>
2495   Likewise, implementations are encouraged not to use the product tokens of
2496   other implementations in order to declare compatibility with them, as this
2497   circumvents the purpose of the field. Finally, they are encouraged not to
2498   use comments to identify products; doing so makes the field value more
2499   difficult to parse.
2500</t>
2501<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="User-Agent"/><iref primary="true" item="Grammar" subitem="User-Agent-v"/>
2502  <x:ref>User-Agent</x:ref>     = "User-Agent" ":" <x:ref>OWS</x:ref> <x:ref>User-Agent-v</x:ref>
2503  <x:ref>User-Agent-v</x:ref>   = <x:ref>product</x:ref> *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2504</artwork></figure>
2505<t>
2506   Example:
2507</t>
2508<figure><artwork type="example">
2509  User-Agent: CERN-LineMode/2.15 libwww/2.17b3
2510</artwork></figure>
2511</section>
2512
2513</section>
2514
2515<section title="IANA Considerations" anchor="IANA.considerations">
2516
2517<section title="Method Registry" anchor="method.registration">
2518<t>
2519  The registration procedure for HTTP Methods is defined by
2520  <xref target="method.registry"/> of this document.
2521</t>
2522<t>
2523   The HTTP Method Registry shall be created at <eref target="http://www.iana.org/assignments/http-methods"/>
2524   and be populated with the registrations below:
2525</t>
2526<?BEGININC p2-semantics.iana-methods ?>
2527<!--AUTOGENERATED FROM extract-method-defs.xslt, do not edit manually-->
2528<texttable align="left" suppress-title="true" anchor="iana.method.registration.table">
2529   <ttcol>Method</ttcol>
2530   <ttcol>Safe</ttcol>
2531   <ttcol>Reference</ttcol>
2532   <c>CONNECT</c>
2533   <c>no</c>
2534   <c>
2535      <xref target="CONNECT"/>
2536   </c>
2537   <c>DELETE</c>
2538   <c>no</c>
2539   <c>
2540      <xref target="DELETE"/>
2541   </c>
2542   <c>GET</c>
2543   <c>yes</c>
2544   <c>
2545      <xref target="GET"/>
2546   </c>
2547   <c>HEAD</c>
2548   <c>yes</c>
2549   <c>
2550      <xref target="HEAD"/>
2551   </c>
2552   <c>OPTIONS</c>
2553   <c>yes</c>
2554   <c>
2555      <xref target="OPTIONS"/>
2556   </c>
2557   <c>POST</c>
2558   <c>no</c>
2559   <c>
2560      <xref target="POST"/>
2561   </c>
2562   <c>PUT</c>
2563   <c>no</c>
2564   <c>
2565      <xref target="PUT"/>
2566   </c>
2567   <c>TRACE</c>
2568   <c>yes</c>
2569   <c>
2570      <xref target="TRACE"/>
2571   </c>
2572</texttable>
2573<!--(END)-->
2574<?ENDINC p2-semantics.iana-methods ?>
2575</section>
2576
2577<section title="Status Code Registry" anchor="status.code.registration">
2578<t>
2579   The registration procedure for HTTP Status Codes &mdash; previously defined
2580   in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/> &mdash; is now defined
2581   by <xref target="status.code.registry"/> of this document.
2582</t>
2583<t>
2584   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
2585   shall be updated with the registrations below:
2586</t>
2587<?BEGININC p2-semantics.iana-status-codes ?>
2588<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
2589<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
2590   <ttcol>Value</ttcol>
2591   <ttcol>Description</ttcol>
2592   <ttcol>Reference</ttcol>
2593   <c>100</c>
2594   <c>Continue</c>
2595   <c>
2596      <xref target="status.100"/>
2597   </c>
2598   <c>101</c>
2599   <c>Switching Protocols</c>
2600   <c>
2601      <xref target="status.101"/>
2602   </c>
2603   <c>200</c>
2604   <c>OK</c>
2605   <c>
2606      <xref target="status.200"/>
2607   </c>
2608   <c>201</c>
2609   <c>Created</c>
2610   <c>
2611      <xref target="status.201"/>
2612   </c>
2613   <c>202</c>
2614   <c>Accepted</c>
2615   <c>
2616      <xref target="status.202"/>
2617   </c>
2618   <c>203</c>
2619   <c>Non-Authoritative Information</c>
2620   <c>
2621      <xref target="status.203"/>
2622   </c>
2623   <c>204</c>
2624   <c>No Content</c>
2625   <c>
2626      <xref target="status.204"/>
2627   </c>
2628   <c>205</c>
2629   <c>Reset Content</c>
2630   <c>
2631      <xref target="status.205"/>
2632   </c>
2633   <c>300</c>
2634   <c>Multiple Choices</c>
2635   <c>
2636      <xref target="status.300"/>
2637   </c>
2638   <c>301</c>
2639   <c>Moved Permanently</c>
2640   <c>
2641      <xref target="status.301"/>
2642   </c>
2643   <c>302</c>
2644   <c>Found</c>
2645   <c>
2646      <xref target="status.302"/>
2647   </c>
2648   <c>303</c>
2649   <c>See Other</c>
2650   <c>
2651      <xref target="status.303"/>
2652   </c>
2653   <c>305</c>
2654   <c>Use Proxy</c>
2655   <c>
2656      <xref target="status.305"/>
2657   </c>
2658   <c>306</c>
2659   <c>(Unused)</c>
2660   <c>
2661      <xref target="status.306"/>
2662   </c>
2663   <c>307</c>
2664   <c>Temporary Redirect</c>
2665   <c>
2666      <xref target="status.307"/>
2667   </c>
2668   <c>400</c>
2669   <c>Bad Request</c>
2670   <c>
2671      <xref target="status.400"/>
2672   </c>
2673   <c>402</c>
2674   <c>Payment Required</c>
2675   <c>
2676      <xref target="status.402"/>
2677   </c>
2678   <c>403</c>
2679   <c>Forbidden</c>
2680   <c>
2681      <xref target="status.403"/>
2682   </c>
2683   <c>404</c>
2684   <c>Not Found</c>
2685   <c>
2686      <xref target="status.404"/>
2687   </c>
2688   <c>405</c>
2689   <c>Method Not Allowed</c>
2690   <c>
2691      <xref target="status.405"/>
2692   </c>
2693   <c>406</c>
2694   <c>Not Acceptable</c>
2695   <c>
2696      <xref target="status.406"/>
2697   </c>
2698   <c>407</c>
2699   <c>Proxy Authentication Required</c>
2700   <c>
2701      <xref target="status.407"/>
2702   </c>
2703   <c>408</c>
2704   <c>Request Timeout</c>
2705   <c>
2706      <xref target="status.408"/>
2707   </c>
2708   <c>409</c>
2709   <c>Conflict</c>
2710   <c>
2711      <xref target="status.409"/>
2712   </c>
2713   <c>410</c>
2714   <c>Gone</c>
2715   <c>
2716      <xref target="status.410"/>
2717   </c>
2718   <c>411</c>
2719   <c>Length Required</c>
2720   <c>
2721      <xref target="status.411"/>
2722   </c>
2723   <c>413</c>
2724   <c>Request Entity Too Large</c>
2725   <c>
2726      <xref target="status.413"/>
2727   </c>
2728   <c>414</c>
2729   <c>URI Too Long</c>
2730   <c>
2731      <xref target="status.414"/>
2732   </c>
2733   <c>415</c>
2734   <c>Unsupported Media Type</c>
2735   <c>
2736      <xref target="status.415"/>
2737   </c>
2738   <c>417</c>
2739   <c>Expectation Failed</c>
2740   <c>
2741      <xref target="status.417"/>
2742   </c>
2743   <c>426</c>
2744   <c>Upgrade Required</c>
2745   <c>
2746      <xref target="status.426"/>
2747   </c>
2748   <c>500</c>
2749   <c>Internal Server Error</c>
2750   <c>
2751      <xref target="status.500"/>
2752   </c>
2753   <c>501</c>
2754   <c>Not Implemented</c>
2755   <c>
2756      <xref target="status.501"/>
2757   </c>
2758   <c>502</c>
2759   <c>Bad Gateway</c>
2760   <c>
2761      <xref target="status.502"/>
2762   </c>
2763   <c>503</c>
2764   <c>Service Unavailable</c>
2765   <c>
2766      <xref target="status.503"/>
2767   </c>
2768   <c>504</c>
2769   <c>Gateway Timeout</c>
2770   <c>
2771      <xref target="status.504"/>
2772   </c>
2773   <c>505</c>
2774   <c>HTTP Version Not Supported</c>
2775   <c>
2776      <xref target="status.505"/>
2777   </c>
2778</texttable>
2779<!--(END)-->
2780<?ENDINC p2-semantics.iana-status-codes ?>
2781</section>
2782<section title="Header Field Registration" anchor="header.field.registration">
2783<t>
2784   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> shall be updated
2785   with the permanent registrations below (see <xref target="RFC3864"/>):
2786</t>
2787<?BEGININC p2-semantics.iana-headers ?>
2788<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
2789<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
2790   <ttcol>Header Field Name</ttcol>
2791   <ttcol>Protocol</ttcol>
2792   <ttcol>Status</ttcol>
2793   <ttcol>Reference</ttcol>
2794
2795   <c>Allow</c>
2796   <c>http</c>
2797   <c>standard</c>
2798   <c>
2799      <xref target="header.allow"/>
2800   </c>
2801   <c>Expect</c>
2802   <c>http</c>
2803   <c>standard</c>
2804   <c>
2805      <xref target="header.expect"/>
2806   </c>
2807   <c>From</c>
2808   <c>http</c>
2809   <c>standard</c>
2810   <c>
2811      <xref target="header.from"/>
2812   </c>
2813   <c>Location</c>
2814   <c>http</c>
2815   <c>standard</c>
2816   <c>
2817      <xref target="header.location"/>
2818   </c>
2819   <c>Max-Forwards</c>
2820   <c>http</c>
2821   <c>standard</c>
2822   <c>
2823      <xref target="header.max-forwards"/>
2824   </c>
2825   <c>Referer</c>
2826   <c>http</c>
2827   <c>standard</c>
2828   <c>
2829      <xref target="header.referer"/>
2830   </c>
2831   <c>Retry-After</c>
2832   <c>http</c>
2833   <c>standard</c>
2834   <c>
2835      <xref target="header.retry-after"/>
2836   </c>
2837   <c>Server</c>
2838   <c>http</c>
2839   <c>standard</c>
2840   <c>
2841      <xref target="header.server"/>
2842   </c>
2843   <c>User-Agent</c>
2844   <c>http</c>
2845   <c>standard</c>
2846   <c>
2847      <xref target="header.user-agent"/>
2848   </c>
2849</texttable>
2850<!--(END)-->
2851<?ENDINC p2-semantics.iana-headers ?>
2852<t>
2853   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
2854</t>
2855</section>
2856</section>
2857
2858<section title="Security Considerations" anchor="security.considerations">
2859<t>
2860   This section is meant to inform application developers, information
2861   providers, and users of the security limitations in HTTP/1.1 as
2862   described by this document. The discussion does not include
2863   definitive solutions to the problems revealed, though it does make
2864   some suggestions for reducing security risks.
2865</t>
2866
2867<section title="Transfer of Sensitive Information" anchor="security.sensitive">
2868<t>
2869   Like any generic data transfer protocol, HTTP cannot regulate the
2870   content of the data that is transferred, nor is there any a priori
2871   method of determining the sensitivity of any particular piece of
2872   information within the context of any given request. Therefore,
2873   applications &SHOULD; supply as much control over this information as
2874   possible to the provider of that information. Four header fields are
2875   worth special mention in this context: Server, Via, Referer and From.
2876</t>
2877<t>
2878   Revealing the specific software version of the server might allow the
2879   server machine to become more vulnerable to attacks against software
2880   that is known to contain security holes. Implementors &SHOULD; make the
2881   Server header field a configurable option.
2882</t>
2883<t>
2884   Proxies which serve as a portal through a network firewall &SHOULD;
2885   take special precautions regarding the transfer of header information
2886   that identifies the hosts behind the firewall. In particular, they
2887   &SHOULD; remove, or replace with sanitized versions, any Via fields
2888   generated behind the firewall.
2889</t>
2890<t>
2891   The Referer header field allows reading patterns to be studied and reverse
2892   links drawn. Although it can be very useful, its power can be abused
2893   if user details are not separated from the information contained in
2894   the Referer. Even when the personal information has been removed, the
2895   Referer header field might indicate a private document's URI whose
2896   publication would be inappropriate.
2897</t>
2898<t>
2899   The information sent in the From field might conflict with the user's
2900   privacy interests or their site's security policy, and hence it
2901   &SHOULD-NOT;  be transmitted without the user being able to disable,
2902   enable, and modify the contents of the field. The user &MUST; be able
2903   to set the contents of this field within a user preference or
2904   application defaults configuration.
2905</t>
2906<t>
2907   We suggest, though do not require, that a convenient toggle interface
2908   be provided for the user to enable or disable the sending of From and
2909   Referer information.
2910</t>
2911<t>
2912   The User-Agent (<xref target="header.user-agent"/>) or Server (<xref
2913   target="header.server"/>) header fields can sometimes be used to determine
2914   that a specific client or server have a particular security hole which might
2915   be exploited. Unfortunately, this same information is often used for other
2916   valuable purposes for which HTTP currently has no better mechanism.
2917</t>
2918<t>
2919   Furthermore, the User-Agent header field may contain enough entropy to be
2920   used, possibly in conjunction with other material, to uniquely identify the
2921   user.
2922</t>
2923<t>
2924   Some methods, like TRACE (<xref target="TRACE"/>), expose information
2925   that was sent in request header fields within the body of their response.
2926   Clients &SHOULD; be careful with sensitive information, like Cookies,
2927   Authorization credentials and other header fields that might be used to
2928   collect data from the client.
2929</t> 
2930</section>
2931
2932<section title="Encoding Sensitive Information in URIs" anchor="encoding.sensitive.information.in.uris">
2933<t>
2934   Because the source of a link might be private information or might
2935   reveal an otherwise private information source, it is strongly
2936   recommended that the user be able to select whether or not the
2937   Referer field is sent. For example, a browser client could have a
2938   toggle switch for browsing openly/anonymously, which would
2939   respectively enable/disable the sending of Referer and From
2940   information.
2941</t>
2942<t>
2943   Clients &SHOULD-NOT; include a Referer header field in a (non-secure)
2944   HTTP request if the referring page was transferred with a secure
2945   protocol.
2946</t>
2947<t>
2948   Authors of services &SHOULD-NOT; use GET-based forms for the submission of
2949   sensitive data because that data will be placed in the request-target. Many
2950   existing servers, proxies, and user agents log or display the request-target
2951   in places where it might be visible to third parties. Such services can
2952   use POST-based form submission instead.
2953</t>
2954</section>
2955
2956<section title="Location Headers and Spoofing" anchor="location.spoofing">
2957<t>
2958   If a single server supports multiple organizations that do not trust
2959   one another, then it &MUST; check the values of Location and Content-Location
2960   header fields in responses that are generated under control of
2961   said organizations to make sure that they do not attempt to
2962   invalidate resources over which they have no authority.
2963</t>
2964</section>
2965
2966<section title="Security Considerations for CONNECT">
2967<t>
2968   Since tunneled data is opaque to the proxy, there are additional
2969   risks to tunneling to other well-known or reserved ports.
2970   A HTTP client CONNECTing to port 25 could relay spam
2971   via SMTP, for example. As such, proxies &SHOULD; restrict CONNECT
2972   access to a small number of known ports.
2973</t>
2974</section>
2975
2976</section>
2977
2978<section title="Acknowledgments" anchor="ack">
2979</section>
2980</middle>
2981<back>
2982
2983<references title="Normative References">
2984
2985<reference anchor="Part1">
2986  <front>
2987    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
2988    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2989      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
2990      <address><email>fielding@gbiv.com</email></address>
2991    </author>
2992    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2993      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2994      <address><email>jg@freedesktop.org</email></address>
2995    </author>
2996    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2997      <organization abbrev="HP">Hewlett-Packard Company</organization>
2998      <address><email>JeffMogul@acm.org</email></address>
2999    </author>
3000    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3001      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3002      <address><email>henrikn@microsoft.com</email></address>
3003    </author>
3004    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3005      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3006      <address><email>LMM@acm.org</email></address>
3007    </author>
3008    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3009      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3010      <address><email>paulle@microsoft.com</email></address>
3011    </author>
3012    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3013      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3014      <address><email>timbl@w3.org</email></address>
3015    </author>
3016    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3017      <organization abbrev="W3C">World Wide Web Consortium</organization>
3018      <address><email>ylafon@w3.org</email></address>
3019    </author>
3020    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3021      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3022      <address><email>julian.reschke@greenbytes.de</email></address>
3023    </author>
3024    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3025  </front>
3026  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
3027  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
3028</reference>
3029
3030<reference anchor="Part3">
3031  <front>
3032    <title abbrev="HTTP/1.1">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
3033    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3034      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3035      <address><email>fielding@gbiv.com</email></address>
3036    </author>
3037    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3038      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3039      <address><email>jg@freedesktop.org</email></address>
3040    </author>
3041    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3042      <organization abbrev="HP">Hewlett-Packard Company</organization>
3043      <address><email>JeffMogul@acm.org</email></address>
3044    </author>
3045    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3046      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3047      <address><email>henrikn@microsoft.com</email></address>
3048    </author>
3049    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3050      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3051      <address><email>LMM@acm.org</email></address>
3052    </author>
3053    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3054      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3055      <address><email>paulle@microsoft.com</email></address>
3056    </author>
3057    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3058      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3059      <address><email>timbl@w3.org</email></address>
3060    </author>
3061    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3062      <organization abbrev="W3C">World Wide Web Consortium</organization>
3063      <address><email>ylafon@w3.org</email></address>
3064    </author>
3065    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3066      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3067      <address><email>julian.reschke@greenbytes.de</email></address>
3068    </author>
3069    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3070  </front>
3071  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p3-payload-&ID-VERSION;"/>
3072  <x:source href="p3-payload.xml" basename="p3-payload"/>
3073</reference>
3074
3075<reference anchor="Part4">
3076  <front>
3077    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
3078    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3079      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3080      <address><email>fielding@gbiv.com</email></address>
3081    </author>
3082    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3083      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3084      <address><email>jg@freedesktop.org</email></address>
3085    </author>
3086    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3087      <organization abbrev="HP">Hewlett-Packard Company</organization>
3088      <address><email>JeffMogul@acm.org</email></address>
3089    </author>
3090    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3091      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3092      <address><email>henrikn@microsoft.com</email></address>
3093    </author>
3094    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3095      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3096      <address><email>LMM@acm.org</email></address>
3097    </author>
3098    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3099      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3100      <address><email>paulle@microsoft.com</email></address>
3101    </author>
3102    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3103      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3104      <address><email>timbl@w3.org</email></address>
3105    </author>
3106    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3107      <organization abbrev="W3C">World Wide Web Consortium</organization>
3108      <address><email>ylafon@w3.org</email></address>
3109    </author>
3110    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3111      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3112      <address><email>julian.reschke@greenbytes.de</email></address>
3113    </author>
3114    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3115  </front>
3116  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
3117  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
3118</reference>
3119
3120<reference anchor="Part5">
3121  <front>
3122    <title abbrev="HTTP/1.1">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
3123    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3124      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3125      <address><email>fielding@gbiv.com</email></address>
3126    </author>
3127    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3128      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3129      <address><email>jg@freedesktop.org</email></address>
3130    </author>
3131    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3132      <organization abbrev="HP">Hewlett-Packard Company</organization>
3133      <address><email>JeffMogul@acm.org</email></address>
3134    </author>
3135    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3136      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3137      <address><email>henrikn@microsoft.com</email></address>
3138    </author>
3139    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3140      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3141      <address><email>LMM@acm.org</email></address>
3142    </author>
3143    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3144      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3145      <address><email>paulle@microsoft.com</email></address>
3146    </author>
3147    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3148      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3149      <address><email>timbl@w3.org</email></address>
3150    </author>
3151    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3152      <organization abbrev="W3C">World Wide Web Consortium</organization>
3153      <address><email>ylafon@w3.org</email></address>
3154    </author>
3155    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3156      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3157      <address><email>julian.reschke@greenbytes.de</email></address>
3158    </author>
3159    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3160  </front>
3161  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p5-range-&ID-VERSION;"/>
3162  <x:source href="p5-range.xml" basename="p5-range"/>
3163</reference>
3164
3165<reference anchor="Part6">
3166  <front>
3167    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
3168    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3169      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3170      <address><email>fielding@gbiv.com</email></address>
3171    </author>
3172    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3173      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3174      <address><email>jg@freedesktop.org</email></address>
3175    </author>
3176    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3177      <organization abbrev="HP">Hewlett-Packard Company</organization>
3178      <address><email>JeffMogul@acm.org</email></address>
3179    </author>
3180    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3181      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3182      <address><email>henrikn@microsoft.com</email></address>
3183    </author>
3184    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3185      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3186      <address><email>LMM@acm.org</email></address>
3187    </author>
3188    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3189      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3190      <address><email>paulle@microsoft.com</email></address>
3191    </author>
3192    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3193      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3194      <address><email>timbl@w3.org</email></address>
3195    </author>
3196    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3197      <organization abbrev="W3C">World Wide Web Consortium</organization>
3198      <address><email>ylafon@w3.org</email></address>
3199    </author>
3200    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
3201      <address><email>mnot@mnot.net</email></address>
3202    </author>
3203    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3204      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3205      <address><email>julian.reschke@greenbytes.de</email></address>
3206    </author>
3207    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3208  </front>
3209  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
3210  <x:source href="p6-cache.xml" basename="p6-cache"/>
3211</reference>
3212
3213<reference anchor="Part7">
3214  <front>
3215    <title abbrev="HTTP/1.1">HTTP/1.1, part 7: Authentication</title>
3216    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3217      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3218      <address><email>fielding@gbiv.com</email></address>
3219    </author>
3220    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3221      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3222      <address><email>jg@freedesktop.org</email></address>
3223    </author>
3224    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3225      <organization abbrev="HP">Hewlett-Packard Company</organization>
3226      <address><email>JeffMogul@acm.org</email></address>
3227    </author>
3228    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3229      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3230      <address><email>henrikn@microsoft.com</email></address>
3231    </author>
3232    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3233      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
3234      <address><email>LMM@acm.org</email></address>
3235    </author>
3236    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3237      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3238      <address><email>paulle@microsoft.com</email></address>
3239    </author>
3240    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3241      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3242      <address><email>timbl@w3.org</email></address>
3243    </author>
3244    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3245      <organization abbrev="W3C">World Wide Web Consortium</organization>
3246      <address><email>ylafon@w3.org</email></address>
3247    </author>
3248    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3249      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3250      <address><email>julian.reschke@greenbytes.de</email></address>
3251    </author>
3252    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3253  </front>
3254  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p7-auth-&ID-VERSION;"/>
3255  <x:source href="p7-auth.xml" basename="p7-auth"/>
3256</reference>
3257
3258<reference anchor="RFC2119">
3259  <front>
3260    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
3261    <author initials="S." surname="Bradner" fullname="Scott Bradner">
3262      <organization>Harvard University</organization>
3263      <address><email>sob@harvard.edu</email></address>
3264    </author>
3265    <date month="March" year="1997"/>
3266  </front>
3267  <seriesInfo name="BCP" value="14"/>
3268  <seriesInfo name="RFC" value="2119"/>
3269</reference>
3270
3271<reference anchor="RFC3986">
3272 <front>
3273  <title abbrev='URI Generic Syntax'>Uniform Resource Identifier (URI): Generic Syntax</title>
3274  <author initials='T.' surname='Berners-Lee' fullname='Tim Berners-Lee'>
3275    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3276    <address>
3277       <email>timbl@w3.org</email>
3278       <uri>http://www.w3.org/People/Berners-Lee/</uri>
3279    </address>
3280  </author>
3281  <author initials='R.' surname='Fielding' fullname='Roy T. Fielding'>
3282    <organization abbrev="Day Software">Day Software</organization>
3283    <address>
3284      <email>fielding@gbiv.com</email>
3285      <uri>http://roy.gbiv.com/</uri>
3286    </address>
3287  </author>
3288  <author initials='L.' surname='Masinter' fullname='Larry Masinter'>
3289    <organization abbrev="Adobe Systems">Adobe Systems Incorporated</organization>
3290    <address>
3291      <email>LMM@acm.org</email>
3292      <uri>http://larry.masinter.net/</uri>
3293    </address>
3294  </author>
3295  <date month='January' year='2005'></date>
3296 </front>
3297 <seriesInfo name="STD" value="66"/>
3298 <seriesInfo name="RFC" value="3986"/>
3299</reference>
3300
3301<reference anchor="RFC5234">
3302  <front>
3303    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
3304    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
3305      <organization>Brandenburg InternetWorking</organization>
3306      <address>
3307        <email>dcrocker@bbiw.net</email>
3308      </address> 
3309    </author>
3310    <author initials="P." surname="Overell" fullname="Paul Overell">
3311      <organization>THUS plc.</organization>
3312      <address>
3313        <email>paul.overell@thus.net</email>
3314      </address>
3315    </author>
3316    <date month="January" year="2008"/>
3317  </front>
3318  <seriesInfo name="STD" value="68"/>
3319  <seriesInfo name="RFC" value="5234"/>
3320</reference>
3321
3322</references>
3323
3324<references title="Informative References">
3325
3326<reference anchor="RFC1945">
3327  <front>
3328    <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1.0</title>
3329    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3330      <organization>MIT, Laboratory for Computer Science</organization>
3331      <address><email>timbl@w3.org</email></address>
3332    </author>
3333    <author initials="R.T." surname="Fielding" fullname="Roy T. Fielding">
3334      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3335      <address><email>fielding@ics.uci.edu</email></address>
3336    </author>
3337    <author initials="H.F." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3338      <organization>W3 Consortium, MIT Laboratory for Computer Science</organization>
3339      <address><email>frystyk@w3.org</email></address>
3340    </author>
3341    <date month="May" year="1996"/>
3342  </front>
3343  <seriesInfo name="RFC" value="1945"/>
3344</reference>
3345
3346<reference anchor="RFC2068">
3347  <front>
3348    <title abbrev="HTTP/1.1">Hypertext Transfer Protocol -- HTTP/1.1</title>
3349    <author initials="R." surname="Fielding" fullname="Roy T. Fielding">
3350      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3351      <address><email>fielding@ics.uci.edu</email></address>
3352    </author>
3353    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3354      <organization>MIT Laboratory for Computer Science</organization>
3355      <address><email>jg@w3.org</email></address>
3356    </author>
3357    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3358      <organization>Digital Equipment Corporation, Western Research Laboratory</organization>
3359      <address><email>mogul@wrl.dec.com</email></address>
3360    </author>
3361    <author initials="H." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3362      <organization>MIT Laboratory for Computer Science</organization>
3363      <address><email>frystyk@w3.org</email></address>
3364    </author>
3365    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3366      <organization>MIT Laboratory for Computer Science</organization>
3367      <address><email>timbl@w3.org</email></address>
3368    </author>
3369    <date month="January" year="1997"/>
3370  </front>
3371  <seriesInfo name="RFC" value="2068"/>
3372</reference>
3373
3374<reference anchor="RFC2616">
3375  <front>
3376    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
3377    <author initials="R." surname="Fielding" fullname="R. Fielding">
3378      <organization>University of California, Irvine</organization>
3379      <address><email>fielding@ics.uci.edu</email></address>
3380    </author>
3381    <author initials="J." surname="Gettys" fullname="J. Gettys">
3382      <organization>W3C</organization>
3383      <address><email>jg@w3.org</email></address>
3384    </author>
3385    <author initials="J." surname="Mogul" fullname="J. Mogul">
3386      <organization>Compaq Computer Corporation</organization>
3387      <address><email>mogul@wrl.dec.com</email></address>
3388    </author>
3389    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
3390      <organization>MIT Laboratory for Computer Science</organization>
3391      <address><email>frystyk@w3.org</email></address>
3392    </author>
3393    <author initials="L." surname="Masinter" fullname="L. Masinter">
3394      <organization>Xerox Corporation</organization>
3395      <address><email>masinter@parc.xerox.com</email></address>
3396    </author>
3397    <author initials="P." surname="Leach" fullname="P. Leach">
3398      <organization>Microsoft Corporation</organization>
3399      <address><email>paulle@microsoft.com</email></address>
3400    </author>
3401    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
3402      <organization>W3C</organization>
3403      <address><email>timbl@w3.org</email></address>
3404    </author>
3405    <date month="June" year="1999"/>
3406  </front>
3407  <seriesInfo name="RFC" value="2616"/>
3408</reference>
3409
3410<reference anchor='RFC2817'>
3411  <front>
3412    <title>Upgrading to TLS Within HTTP/1.1</title>
3413    <author initials='R.' surname='Khare' fullname='R. Khare'>
3414      <organization>4K Associates / UC Irvine</organization>
3415      <address><email>rohit@4K-associates.com</email></address>
3416    </author>
3417    <author initials='S.' surname='Lawrence' fullname='S. Lawrence'>
3418      <organization>Agranat Systems, Inc.</organization>
3419      <address><email>lawrence@agranat.com</email></address>
3420    </author>
3421    <date year='2000' month='May' />
3422  </front>
3423  <seriesInfo name='RFC' value='2817' />
3424</reference>
3425
3426<reference anchor='RFC3864'>
3427  <front>
3428    <title>Registration Procedures for Message Header Fields</title>
3429    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
3430      <organization>Nine by Nine</organization>
3431      <address><email>GK-IETF@ninebynine.org</email></address>
3432    </author>
3433    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
3434      <organization>BEA Systems</organization>
3435      <address><email>mnot@pobox.com</email></address>
3436    </author>
3437    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
3438      <organization>HP Labs</organization>
3439      <address><email>JeffMogul@acm.org</email></address>
3440    </author>
3441    <date year='2004' month='September' />
3442  </front>
3443  <seriesInfo name='BCP' value='90' />
3444  <seriesInfo name='RFC' value='3864' />
3445</reference>
3446
3447<reference anchor='RFC5226'>
3448  <front>
3449    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
3450    <author initials='T.' surname='Narten' fullname='T. Narten'>
3451      <organization>IBM</organization>
3452      <address><email>narten@us.ibm.com</email></address>
3453    </author>
3454    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
3455      <organization>Google</organization>
3456      <address><email>Harald@Alvestrand.no</email></address>
3457    </author>
3458    <date year='2008' month='May' />
3459  </front>
3460  <seriesInfo name='BCP' value='26' />
3461  <seriesInfo name='RFC' value='5226' />
3462</reference>
3463
3464<reference anchor="RFC5322">
3465  <front>
3466    <title>Internet Message Format</title>
3467    <author initials="P." surname="Resnick" fullname="P. Resnick">
3468      <organization>Qualcomm Incorporated</organization>
3469    </author>
3470    <date year="2008" month="October"/>
3471  </front> 
3472  <seriesInfo name="RFC" value="5322"/>
3473</reference>
3474
3475</references>
3476
3477<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
3478<t>
3479  This document takes over the Status Code Registry, previously defined
3480  in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/>.
3481  (<xref target="status.code.registry"/>)
3482</t>
3483<t>
3484  Clarify definition of POST.
3485  (<xref target="POST"/>)
3486</t>
3487<t>
3488  Take over definition of CONNECT method from <xref target="RFC2817"/>.
3489  (<xref target="CONNECT"/>)
3490</t>
3491<t>
3492  Failed to consider that there are
3493  many other request methods that are safe to automatically redirect,
3494  and further that the user agent is able to make that determination
3495  based on the request method semantics.
3496  (Sections <xref format="counter" target="status.301"/>,
3497  <xref format="counter" target="status.302"/> and
3498  <xref format="counter" target="status.307"/>)
3499</t>
3500<t>
3501  Deprecate 305 Use Proxy status code, because user agents did not implement it.
3502  It used to indicate that the target resource must be accessed through the
3503  proxy given by the Location field. The Location field gave the URI of the
3504  proxy. The recipient was expected to repeat this single request via the proxy.
3505  (<xref target="status.305"/>)
3506</t>
3507<t>
3508  Define status 426 (Upgrade Required) (this was incorporated from
3509  <xref target="RFC2817"/>).
3510  (<xref target="status.426"/>)
3511</t>
3512<t>
3513  Reclassify "Allow" as response header field, removing the option to
3514  specify it in a PUT request.
3515  Relax the server requirement on the contents of the Allow header field and
3516  remove requirement on clients to always trust the header field value.
3517  (<xref target="header.allow"/>)
3518</t>
3519<t>
3520  Correct syntax of Location header field to allow URI references (including
3521  relative references and fragments), as referred symbol "absoluteURI" wasn't
3522  what was expected, and add some clarifications as to when use of fragments
3523  would not be appropriate.
3524  (<xref target="header.location"/>)
3525</t>
3526<t>
3527  Restrict Max-Forwards header field to OPTIONS and TRACE (previously,
3528  extension methods could have used it as well).
3529  (<xref target="header.max-forwards"/>)
3530</t>
3531<t>
3532  Allow Referer field value of "about:blank" as alternative to not specifying it.
3533  (<xref target="header.referer"/>)
3534</t>
3535<t>
3536  In the description of the Server header field, the Via field
3537  was described as a SHOULD. The requirement was and is stated
3538  correctly in the description of the Via header field in &header-via;.
3539  (<xref target="header.server"/>)
3540</t>
3541</section>
3542
3543<?BEGININC p2-semantics.abnf-appendix ?>
3544<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
3545<figure>
3546<artwork type="abnf" name="p2-semantics.parsed-abnf">
3547<x:ref>Accept</x:ref> = &lt;Accept, defined in [Part3], Section 6.1&gt;
3548<x:ref>Accept-Charset</x:ref> = &lt;Accept-Charset, defined in [Part3], Section 6.2&gt;
3549<x:ref>Accept-Encoding</x:ref> = &lt;Accept-Encoding, defined in [Part3], Section 6.3&gt;
3550<x:ref>Accept-Language</x:ref> = &lt;Accept-Language, defined in [Part3], Section 6.4&gt;
3551<x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in [Part5], Section 5.1&gt;
3552<x:ref>Age</x:ref> = &lt;Age, defined in [Part6], Section 3.1&gt;
3553<x:ref>Allow</x:ref> = "Allow:" OWS Allow-v
3554<x:ref>Allow-v</x:ref> = [ ( "," / Method ) *( OWS "," [ OWS Method ] ) ]
3555<x:ref>Authorization</x:ref> = &lt;Authorization, defined in [Part7], Section 4.1&gt;
3556
3557<x:ref>ETag</x:ref> = &lt;ETag, defined in [Part4], Section 6.1&gt;
3558<x:ref>Expect</x:ref> = "Expect:" OWS Expect-v
3559<x:ref>Expect-v</x:ref> = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] )
3560
3561<x:ref>From</x:ref> = "From:" OWS From-v
3562<x:ref>From-v</x:ref> = mailbox
3563
3564<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part1], Section 6.1&gt;
3565<x:ref>Host</x:ref> = &lt;Host, defined in [Part1], Section 2.6&gt;
3566
3567<x:ref>If-Match</x:ref> = &lt;If-Match, defined in [Part4], Section 6.2&gt;
3568If-Modified-Since =
3569 &lt;If-Modified-Since, defined in [Part4], Section 6.3&gt;
3570<x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in [Part4], Section 6.4&gt;
3571<x:ref>If-Range</x:ref> = &lt;If-Range, defined in [Part5], Section 5.3&gt;
3572If-Unmodified-Since =
3573 &lt;If-Unmodified-Since, defined in [Part4], Section 6.5&gt;
3574
3575<x:ref>Location</x:ref> = "Location:" OWS Location-v
3576<x:ref>Location-v</x:ref> = URI-reference
3577
3578<x:ref>Max-Forwards</x:ref> = "Max-Forwards:" OWS Max-Forwards-v
3579<x:ref>Max-Forwards-v</x:ref> = 1*DIGIT
3580<x:ref>Method</x:ref> = token
3581
3582<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
3583
3584Proxy-Authenticate =
3585 &lt;Proxy-Authenticate, defined in [Part7], Section 4.2&gt;
3586Proxy-Authorization =
3587 &lt;Proxy-Authorization, defined in [Part7], Section 4.3&gt;
3588
3589<x:ref>RWS</x:ref> = &lt;RWS, defined in [Part1], Section 1.2.2&gt;
3590<x:ref>Range</x:ref> = &lt;Range, defined in [Part5], Section 5.4&gt;
3591<x:ref>Reason-Phrase</x:ref> = *( WSP / VCHAR / obs-text )
3592<x:ref>Referer</x:ref> = "Referer:" OWS Referer-v
3593<x:ref>Referer-v</x:ref> = absolute-URI / partial-URI
3594<x:ref>Retry-After</x:ref> = "Retry-After:" OWS Retry-After-v
3595<x:ref>Retry-After-v</x:ref> = HTTP-date / delta-seconds
3596
3597<x:ref>Server</x:ref> = "Server:" OWS Server-v
3598<x:ref>Server-v</x:ref> = product *( RWS ( product / comment ) )
3599<x:ref>Status-Code</x:ref> = 3DIGIT
3600
3601<x:ref>TE</x:ref> = &lt;TE, defined in [Part1], Section 9.5&gt;
3602
3603<x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in [Part1], Section 2.6&gt;
3604<x:ref>User-Agent</x:ref> = "User-Agent:" OWS User-Agent-v
3605<x:ref>User-Agent-v</x:ref> = product *( RWS ( product / comment ) )
3606
3607<x:ref>Vary</x:ref> = &lt;Vary, defined in [Part6], Section 3.5&gt;
3608
3609WWW-Authenticate =
3610 &lt;WWW-Authenticate, defined in [Part7], Section 4.4&gt;
3611
3612<x:ref>absolute-URI</x:ref> = &lt;absolute-URI, defined in [Part1], Section 2.6&gt;
3613
3614<x:ref>comment</x:ref> = &lt;comment, defined in [Part1], Section 3.2&gt;
3615
3616<x:ref>delta-seconds</x:ref> = 1*DIGIT
3617
3618<x:ref>expect-params</x:ref> = ";" token [ "=" ( token / quoted-string ) ]
3619<x:ref>expectation</x:ref> = "100-continue" / expectation-extension
3620<x:ref>expectation-extension</x:ref> = token [ "=" ( token / quoted-string )
3621 *expect-params ]
3622
3623<x:ref>mailbox</x:ref> = &lt;mailbox, defined in [RFC5322], Section 3.4&gt;
3624
3625<x:ref>obs-text</x:ref> = &lt;obs-text, defined in [Part1], Section 1.2.2&gt;
3626
3627<x:ref>partial-URI</x:ref> = &lt;partial-URI, defined in [Part1], Section 2.6&gt;
3628<x:ref>product</x:ref> = &lt;product, defined in [Part1], Section 6.3&gt;
3629
3630<x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in [Part1], Section 1.2.2&gt;
3631
3632<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 1.2.2&gt;
3633</artwork>
3634</figure>
3635<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
3636; Accept defined but not used
3637; Accept-Charset defined but not used
3638; Accept-Encoding defined but not used
3639; Accept-Language defined but not used
3640; Accept-Ranges defined but not used
3641; Age defined but not used
3642; Allow defined but not used
3643; Authorization defined but not used
3644; ETag defined but not used
3645; Expect defined but not used
3646; From defined but not used
3647; Host defined but not used
3648; If-Match defined but not used
3649; If-Modified-Since defined but not used
3650; If-None-Match defined but not used
3651; If-Range defined but not used
3652; If-Unmodified-Since defined but not used
3653; Location defined but not used
3654; Max-Forwards defined but not used
3655; Proxy-Authenticate defined but not used
3656; Proxy-Authorization defined but not used
3657; Range defined but not used
3658; Reason-Phrase defined but not used
3659; Referer defined but not used
3660; Retry-After defined but not used
3661; Server defined but not used
3662; Status-Code defined but not used
3663; TE defined but not used
3664; User-Agent defined but not used
3665; Vary defined but not used
3666; WWW-Authenticate defined but not used
3667</artwork></figure></section>
3668<?ENDINC p2-semantics.abnf-appendix ?>
3669
3670<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
3671
3672<section title="Since RFC 2616">
3673<t>
3674  Extracted relevant partitions from <xref target="RFC2616"/>.
3675</t>
3676</section>
3677
3678<section title="Since draft-ietf-httpbis-p2-semantics-00">
3679<t>
3680  Closed issues:
3681  <list style="symbols"> 
3682    <t>
3683      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/5"/>:
3684      "Via is a MUST"
3685      (<eref target="http://purl.org/NET/http-errata#via-must"/>)
3686    </t>
3687    <t>
3688      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/6"/>:
3689      "Fragments allowed in Location"
3690      (<eref target="http://purl.org/NET/http-errata#location-fragments"/>)
3691    </t>
3692    <t>
3693      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3694      "Safe Methods vs Redirection"
3695      (<eref target="http://purl.org/NET/http-errata#saferedirect"/>)
3696    </t>
3697    <t>
3698      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/17"/>:
3699      "Revise description of the POST method"
3700      (<eref target="http://purl.org/NET/http-errata#post"/>)
3701    </t>
3702    <t>
3703      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
3704      "Normative and Informative references"
3705    </t>
3706    <t>
3707      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/42"/>:
3708      "RFC2606 Compliance"
3709    </t>
3710    <t>
3711      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/65"/>:
3712      "Informative references"
3713    </t>
3714    <t>
3715      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/84"/>:
3716      "Redundant cross-references"
3717    </t>
3718  </list>
3719</t>
3720<t>
3721  Other changes:
3722  <list style="symbols"> 
3723    <t>
3724      Move definitions of 304 and 412 condition codes to <xref target="Part4"/>
3725    </t>
3726  </list>
3727</t>
3728</section>
3729
3730<section title="Since draft-ietf-httpbis-p2-semantics-01">
3731<t>
3732  Closed issues:
3733  <list style="symbols"> 
3734    <t>
3735      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/21"/>:
3736      "PUT side effects"
3737    </t>
3738    <t>
3739      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/91"/>:
3740      "Duplicate Host header requirements"
3741    </t>
3742  </list>
3743</t>
3744<t>
3745  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3746  <list style="symbols"> 
3747    <t>
3748      Move "Product Tokens" section (back) into Part 1, as "token" is used
3749      in the definition of the Upgrade header field.
3750    </t>
3751    <t>
3752      Add explicit references to BNF syntax and rules imported from other parts of the specification.
3753    </t>
3754    <t>
3755      Copy definition of delta-seconds from Part6 instead of referencing it.
3756    </t>
3757  </list>
3758</t>
3759</section>
3760
3761<section title="Since draft-ietf-httpbis-p2-semantics-02" anchor="changes.since.02">
3762<t>
3763  Closed issues:
3764  <list style="symbols"> 
3765    <t>
3766      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/24"/>:
3767      "Requiring Allow in 405 responses"
3768    </t>
3769    <t>
3770      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/59"/>:
3771      "Status Code Registry"
3772    </t>
3773    <t>
3774      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/61"/>:
3775      "Redirection vs. Location"
3776    </t>
3777    <t>
3778      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/70"/>:
3779      "Cacheability of 303 response"
3780    </t>
3781    <t>
3782      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/76"/>:
3783      "305 Use Proxy"
3784    </t>
3785    <t>
3786      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/105"/>:
3787      "Classification for Allow header"
3788    </t>
3789    <t>
3790      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
3791      "PUT - 'store under' vs 'store at'"
3792    </t>
3793  </list>
3794</t>
3795<t>
3796  Ongoing work on IANA Message Header Field Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
3797  <list style="symbols"> 
3798    <t>
3799      Reference RFC 3984, and update header field registrations for headers defined
3800      in this document.
3801    </t>
3802  </list>
3803</t>
3804<t>
3805  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3806  <list style="symbols"> 
3807    <t>
3808      Replace string literals when the string really is case-sensitive (method).
3809    </t>
3810  </list>
3811</t>
3812</section>
3813
3814<section title="Since draft-ietf-httpbis-p2-semantics-03" anchor="changes.since.03">
3815<t>
3816  Closed issues:
3817  <list style="symbols"> 
3818    <t>
3819      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/98"/>:
3820      "OPTIONS request bodies"
3821    </t>
3822    <t>
3823      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/119"/>:
3824      "Description of CONNECT should refer to RFC2817"
3825    </t>
3826    <t>
3827      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/125"/>:
3828      "Location Content-Location reference request/response mixup"
3829    </t>
3830  </list>
3831</t>
3832<t>
3833  Ongoing work on Method Registry (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/72"/>):
3834  <list style="symbols"> 
3835    <t>
3836      Added initial proposal for registration process, plus initial
3837      content (non-HTTP/1.1 methods to be added by a separate specification).
3838    </t>
3839  </list>
3840</t>
3841</section>
3842
3843<section title="Since draft-ietf-httpbis-p2-semantics-04" anchor="changes.since.04">
3844<t>
3845  Closed issues:
3846  <list style="symbols"> 
3847    <t>
3848      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/103"/>:
3849      "Content-*"
3850    </t>
3851    <t>
3852      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/132"/>:
3853      "RFC 2822 is updated by RFC 5322"
3854    </t>
3855  </list>
3856</t>
3857<t>
3858  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3859  <list style="symbols"> 
3860    <t>
3861      Use "/" instead of "|" for alternatives.
3862    </t>
3863    <t>
3864      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
3865      whitespace ("OWS") and required whitespace ("RWS").
3866    </t>
3867    <t>
3868      Rewrite ABNFs to spell out whitespace rules, factor out
3869      header field value format definitions.
3870    </t>
3871  </list>
3872</t>
3873</section>
3874
3875<section title="Since draft-ietf-httpbis-p2-semantics-05" anchor="changes.since.05">
3876<t>
3877  Closed issues:
3878  <list style="symbols"> 
3879    <t>
3880      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/94"/>:
3881      "Reason-Phrase BNF"
3882    </t>
3883  </list>
3884</t>
3885<t>
3886  Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3887  <list style="symbols"> 
3888    <t>
3889      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
3890    </t>
3891  </list>
3892</t>
3893</section>
3894
3895<section title="Since draft-ietf-httpbis-p2-semantics-06" anchor="changes.since.06">
3896<t>
3897  Closed issues:
3898  <list style="symbols"> 
3899    <t>
3900      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/144"/>:
3901      "Clarify when Referer is sent"
3902    </t>
3903    <t>
3904      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/164"/>:
3905      "status codes vs methods"
3906    </t>
3907    <t>
3908      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/170"/>:
3909      "Do not require "updates" relation for specs that register status codes or method names"
3910    </t>
3911  </list>
3912</t>
3913</section>
3914
3915<section title="Since draft-ietf-httpbis-p2-semantics-07" anchor="changes.since.07">
3916<t>
3917  Closed issues:
3918  <list style="symbols"> 
3919    <t>
3920      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/27"/>:
3921      "Idempotency"
3922    </t>
3923    <t>
3924      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/33"/>:
3925      "TRACE security considerations"
3926    </t>
3927    <t>
3928      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/110"/>:
3929      "Clarify rules for determining what entities a response carries"
3930    </t>
3931    <t>
3932      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/140"/>:
3933      "update note citing RFC 1945 and 2068"
3934    </t>
3935    <t>
3936      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/182"/>:
3937      "update note about redirect limit"
3938    </t>
3939    <t>
3940      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/191"/>:
3941      "Location header ABNF should use 'URI'"
3942    </t>
3943    <t>
3944      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/192"/>:
3945      "fragments in Location vs status 303"
3946    </t>
3947    <t>
3948      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/198"/>:
3949      "move IANA registrations for optional status codes"
3950    </t>
3951  </list>
3952</t>
3953<t>
3954  Partly resolved issues:
3955  <list style="symbols"> 
3956    <t>
3957      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/171"/>:
3958      "Are OPTIONS and TRACE safe?"
3959    </t>
3960  </list>
3961</t>
3962</section>
3963
3964<section title="Since draft-ietf-httpbis-p2-semantics-08" anchor="changes.since.08">
3965<t>
3966  Closed issues:
3967  <list style="symbols"> 
3968    <t>
3969      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3970      "Safe Methods vs Redirection" (we missed the introduction to the 3xx
3971      status codes when fixing this previously)
3972    </t>
3973  </list>
3974</t>
3975</section>
3976
3977<section title="Since draft-ietf-httpbis-p2-semantics-09" anchor="changes.since.09">
3978<t>
3979  Closed issues:
3980  <list style="symbols"> 
3981    <t>
3982      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/43"/>:
3983      "Fragment combination / precedence during redirects"
3984    </t>
3985  </list>
3986</t>
3987<t>
3988  Partly resolved issues:
3989  <list style="symbols"> 
3990    <t>
3991      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/185"/>:
3992      "Location header payload handling"
3993    </t>
3994    <t>
3995      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/196"/>:
3996      "Term for the requested resource's URI"
3997    </t>
3998  </list>
3999</t>
4000</section>
4001
4002<section title="Since draft-ietf-httpbis-p2-semantics-10" anchor="changes.since.10">
4003<t>
4004  Closed issues:
4005  <list style="symbols"> 
4006    <t>
4007      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/69"/>:
4008      "Clarify 'Requested Variant'"
4009    </t>
4010    <t>
4011      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/109"/>:
4012      "Clarify entity / representation / variant terminology"
4013    </t>
4014    <t>
4015      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/139"/>:
4016      "Methods and Caching"
4017    </t>
4018    <t>
4019      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/190"/>:
4020      "OPTIONS vs Max-Forwards"
4021    </t>
4022    <t>
4023      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/199"/>:
4024      "Status codes and caching"
4025    </t>
4026    <t>
4027      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>:
4028      "consider removing the 'changes from 2068' sections"
4029    </t>
4030  </list>
4031</t>
4032</section>
4033
4034<section title="Since draft-ietf-httpbis-p2-semantics-11" anchor="changes.since.11">
4035<t>
4036  Closed issues:
4037  <list style="symbols"> 
4038    <t>
4039      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/229"/>:
4040      "Considerations for new status codes"
4041    </t>
4042    <t>
4043      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/230"/>:
4044      "Considerations for new methods"
4045    </t>
4046    <t>
4047      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/232"/>:
4048      "User-Agent guidelines" (relating to the 'User-Agent' header field)
4049    </t>
4050  </list>
4051</t>
4052</section>
4053
4054<section title="Since draft-ietf-httpbis-p2-semantics-12" anchor="changes.since.12">
4055<t>
4056  Closed issues:
4057  <list style="symbols"> 
4058    <t>
4059      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/43"/>:
4060      "Fragment combination / precedence during redirects" (added warning
4061      about having a fragid on the redirect may cause inconvenience in
4062      some cases)
4063    </t>
4064    <t>
4065      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/88"/>:
4066      "205 Bodies"
4067    </t>
4068    <t>
4069      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/203"/>:
4070      "Max-Forwards vs extension methods"
4071    </t>
4072    <t>
4073      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/137"/>:
4074      "duplicate ABNF for Reason-Phrase"
4075    </t>
4076    <t>
4077      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/226"/>:
4078      "proxies not supporting certain methods"
4079    </t>
4080    <t>
4081      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/239"/>:
4082      "Migrate CONNECT from RFC2817 to p2"
4083    </t>
4084    <t>
4085      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/240"/>:
4086      "Migrate Upgrade details from RFC2817"
4087    </t>
4088    <t>
4089      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/225"/>:
4090      "PUT side effect: invalidation or just stale?"
4091    </t>
4092    <t>
4093      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/275"/>:
4094      "duplicate ABNF for 'Method'"
4095    </t>
4096    <t>
4097      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/276"/>:
4098      "untangle ABNFs for header fields"
4099    </t>
4100  </list>
4101</t>
4102</section>
4103
4104</section>
4105
4106</back>
4107</rfc>
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