source: draft-ietf-httpbis/latest/p2-semantics.xml @ 1061

Last change on this file since 1061 was 1061, checked in by mnot@…, 9 years ago

Move CONNECT text from RFC2817; fixes #239.

  • Property svn:eol-style set to native
File size: 167.7 KB
Line 
1<?xml version="1.0" encoding="utf-8"?>
2<?xml-stylesheet type='text/xsl' href='../myxml2rfc.xslt'?>
3<!DOCTYPE rfc [
4  <!ENTITY MAY "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MAY</bcp14>">
5  <!ENTITY MUST "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST</bcp14>">
6  <!ENTITY MUST-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST NOT</bcp14>">
7  <!ENTITY OPTIONAL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>OPTIONAL</bcp14>">
8  <!ENTITY RECOMMENDED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>RECOMMENDED</bcp14>">
9  <!ENTITY REQUIRED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>REQUIRED</bcp14>">
10  <!ENTITY SHALL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL</bcp14>">
11  <!ENTITY SHALL-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL NOT</bcp14>">
12  <!ENTITY SHOULD "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD</bcp14>">
13  <!ENTITY SHOULD-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD NOT</bcp14>">
14  <!ENTITY ID-VERSION "latest">
15  <!ENTITY ID-MONTH "October">
16  <!ENTITY ID-YEAR "2010">
17  <!ENTITY notation                   "<xref target='Part1' x:rel='#notation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
18  <!ENTITY messaging                  "<xref target='Part1' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
19  <!ENTITY payload                    "<xref target='Part3' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
20  <!ENTITY conditional                "<xref target='Part4' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
21  <!ENTITY range                      "<xref target='Part5' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
22  <!ENTITY caching                    "<xref target='Part6' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
23  <!ENTITY auth                       "<xref target='Part7' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
24  <!ENTITY combining-responses        "<xref target='Part6' x:rel='#combining.responses' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
25  <!ENTITY content-negotiation        "<xref target='Part3' x:rel='#content.negotiation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
26  <!ENTITY notation-abnf              "<xref target='Part1' x:rel='#notation.abnf' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
27  <!ENTITY basic-rules                "<xref target='Part1' x:rel='#basic.rules' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
28  <!ENTITY uri                        "<xref target='Part1' x:rel='#uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
29  <!ENTITY effective-request-uri      "<xref target='Part1' x:rel='#effective.request.uri' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
30  <!ENTITY full-date                  "<xref target='Part1' x:rel='#date.time.formats.full.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
31  <!ENTITY http-url                   "<xref target='Part1' x:rel='#http-url' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
32  <!ENTITY http-version               "<xref target='Part1' x:rel='#http.version' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
33  <!ENTITY use100                     "<xref target='Part1' x:rel='#use.of.the.100.status' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
34  <!ENTITY qvalue                     "<xref target='Part3' x:rel='#quality.values' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
35  <!ENTITY header-accept              "<xref target='Part3' x:rel='#header.accept' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
36  <!ENTITY header-accept-charset      "<xref target='Part3' x:rel='#header.accept-charset' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
37  <!ENTITY header-accept-encoding     "<xref target='Part3' x:rel='#header.accept-encoding' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
38  <!ENTITY header-accept-language     "<xref target='Part3' x:rel='#header.accept-language' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
39  <!ENTITY header-accept-ranges       "<xref target='Part5' x:rel='#header.accept-ranges' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
40  <!ENTITY header-age                 "<xref target='Part6' x:rel='#header.age' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
41  <!ENTITY header-authorization       "<xref target='Part7' x:rel='#header.authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
42  <!ENTITY header-cache-control       "<xref target='Part6' x:rel='#header.cache-control' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
43  <!ENTITY header-content-location    "<xref target='Part3' x:rel='#header.content-location' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
44  <!ENTITY header-content-range       "<xref target='Part5' x:rel='#header.content-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
45  <!ENTITY header-etag                "<xref target='Part4' x:rel='#header.etag' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
46  <!ENTITY header-expires             "<xref target='Part6' x:rel='#header.expires' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
47  <!ENTITY header-fields              "<xref target='Part1' x:rel='#header.fields' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
48  <!ENTITY header-host                "<xref target='Part1' x:rel='#header.host' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
49  <!ENTITY header-if-match            "<xref target='Part4' x:rel='#header.if-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
50  <!ENTITY header-if-modified-since   "<xref target='Part4' x:rel='#header.if-modified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
51  <!ENTITY header-if-none-match       "<xref target='Part4' x:rel='#header.if-none-match' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
52  <!ENTITY header-if-range            "<xref target='Part5' x:rel='#header.if-range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
53  <!ENTITY header-if-unmodified-since "<xref target='Part4' x:rel='#header.if-unmodified-since' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
54  <!ENTITY header-pragma              "<xref target='Part6' x:rel='#header.pragma' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
55  <!ENTITY header-proxy-authenticate  "<xref target='Part7' x:rel='#header.proxy-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
56  <!ENTITY header-proxy-authorization "<xref target='Part7' x:rel='#header.proxy-authorization' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
57  <!ENTITY header-range               "<xref target='Part5' x:rel='#header.range' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
58  <!ENTITY header-upgrade             "<xref target='Part1' x:rel='#header.upgrade' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
59  <!ENTITY header-te                  "<xref target='Part1' x:rel='#header.te' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
60  <!ENTITY header-vary                "<xref target='Part6' x:rel='#header.vary' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
61  <!ENTITY header-via                 "<xref target='Part1' x:rel='#header.via' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
62  <!ENTITY header-warning             "<xref target='Part6' x:rel='#header.warning' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
63  <!ENTITY header-www-authenticate    "<xref target='Part7' x:rel='#header.www-authenticate' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
64  <!ENTITY message-body               "<xref target='Part1' x:rel='#message.body' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
65  <!ENTITY product-tokens             "<xref target='Part1' x:rel='#product.tokens' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
66  <!ENTITY media-type-message-http    "<xref target='Part1' x:rel='#internet.media.type.message.http' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
67  <!ENTITY status-206                 "<xref target='Part5' x:rel='#status.206' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
68  <!ENTITY status-304                 "<xref target='Part4' x:rel='#status.304' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
69  <!ENTITY status-401                 "<xref target='Part7' x:rel='#status.401' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
70  <!ENTITY status-407                 "<xref target='Part7' x:rel='#status.407' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
71  <!ENTITY status-412                 "<xref target='Part4' x:rel='#status.412' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
72  <!ENTITY status-416                 "<xref target='Part5' x:rel='#status.416' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
73  <!ENTITY p4-status-codes            "<xref target='Part4' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
74  <!ENTITY p5-status-codes            "<xref target='Part5' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
75  <!ENTITY p7-status-codes            "<xref target='Part7' x:rel='#status.code.definitions' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
76  <!ENTITY p6-heuristic               "<xref target='Part6' x:rel='#heuristic.freshness' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
77  <!ENTITY p6-explicit               "<xref target='Part6' x:rel='#calculating.freshness.lifetime' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
78]>
79<?rfc toc="yes" ?>
80<?rfc symrefs="yes" ?>
81<?rfc sortrefs="yes" ?>
82<?rfc compact="yes"?>
83<?rfc subcompact="no" ?>
84<?rfc linkmailto="no" ?>
85<?rfc editing="no" ?>
86<?rfc comments="yes"?>
87<?rfc inline="yes"?>
88<?rfc rfcedstyle="yes"?>
89<?rfc-ext allow-markup-in-artwork="yes" ?>
90<?rfc-ext include-references-in-index="yes" ?>
91<rfc obsoletes="2616" updates="2817" category="std" x:maturity-level="draft"
92     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"
93     xmlns:x='http://purl.org/net/xml2rfc/ext'
94     xmlns:rdf='http://www.w3.org/1999/02/22-rdf-syntax-ns#'>
95<front>
96
97  <title abbrev="HTTP/1.1, Part 2">HTTP/1.1, part 2: Message Semantics</title>
98
99  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
100    <organization abbrev="Day Software">Day Software</organization>
101    <address>
102      <postal>
103        <street>23 Corporate Plaza DR, Suite 280</street>
104        <city>Newport Beach</city>
105        <region>CA</region>
106        <code>92660</code>
107        <country>USA</country>
108      </postal>
109      <phone>+1-949-706-5300</phone>
110      <facsimile>+1-949-706-5305</facsimile>
111      <email>fielding@gbiv.com</email>
112      <uri>http://roy.gbiv.com/</uri>
113    </address>
114  </author>
115
116  <author initials="J." surname="Gettys" fullname="Jim Gettys">
117    <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
118    <address>
119      <postal>
120        <street>21 Oak Knoll Road</street>
121        <city>Carlisle</city>
122        <region>MA</region>
123        <code>01741</code>
124        <country>USA</country>
125      </postal>
126      <email>jg@freedesktop.org</email>
127      <uri>http://gettys.wordpress.com/</uri>
128    </address>
129  </author>
130 
131  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
132    <organization abbrev="HP">Hewlett-Packard Company</organization>
133    <address>
134      <postal>
135        <street>HP Labs, Large Scale Systems Group</street>
136        <street>1501 Page Mill Road, MS 1177</street>
137        <city>Palo Alto</city>
138        <region>CA</region>
139        <code>94304</code>
140        <country>USA</country>
141      </postal>
142      <email>JeffMogul@acm.org</email>
143    </address>
144  </author>
145
146  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
147    <organization abbrev="Microsoft">Microsoft Corporation</organization>
148    <address>
149      <postal>
150        <street>1 Microsoft Way</street>
151        <city>Redmond</city>
152        <region>WA</region>
153        <code>98052</code>
154        <country>USA</country>
155      </postal>
156      <email>henrikn@microsoft.com</email>
157    </address>
158  </author>
159
160  <author initials="L." surname="Masinter" fullname="Larry Masinter">
161    <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
162    <address>
163      <postal>
164        <street>345 Park Ave</street>
165        <city>San Jose</city>
166        <region>CA</region>
167        <code>95110</code>
168        <country>USA</country>
169      </postal>
170      <email>LMM@acm.org</email>
171      <uri>http://larry.masinter.net/</uri>
172    </address>
173  </author>
174 
175  <author initials="P." surname="Leach" fullname="Paul J. Leach">
176    <organization abbrev="Microsoft">Microsoft Corporation</organization>
177    <address>
178      <postal>
179        <street>1 Microsoft Way</street>
180        <city>Redmond</city>
181        <region>WA</region>
182        <code>98052</code>
183      </postal>
184      <email>paulle@microsoft.com</email>
185    </address>
186  </author>
187   
188  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
189    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
190    <address>
191      <postal>
192        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
193        <street>The Stata Center, Building 32</street>
194        <street>32 Vassar Street</street>
195        <city>Cambridge</city>
196        <region>MA</region>
197        <code>02139</code>
198        <country>USA</country>
199      </postal>
200      <email>timbl@w3.org</email>
201      <uri>http://www.w3.org/People/Berners-Lee/</uri>
202    </address>
203  </author>
204
205  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
206    <organization abbrev="W3C">World Wide Web Consortium</organization>
207    <address>
208      <postal>
209        <street>W3C / ERCIM</street>
210        <street>2004, rte des Lucioles</street>
211        <city>Sophia-Antipolis</city>
212        <region>AM</region>
213        <code>06902</code>
214        <country>France</country>
215      </postal>
216      <email>ylafon@w3.org</email>
217      <uri>http://www.raubacapeu.net/people/yves/</uri>
218    </address>
219  </author>
220
221  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
222    <organization abbrev="greenbytes">greenbytes GmbH</organization>
223    <address>
224      <postal>
225        <street>Hafenweg 16</street>
226        <city>Muenster</city><region>NW</region><code>48155</code>
227        <country>Germany</country>
228      </postal>
229      <phone>+49 251 2807760</phone>
230      <facsimile>+49 251 2807761</facsimile>
231      <email>julian.reschke@greenbytes.de</email>
232      <uri>http://greenbytes.de/tech/webdav/</uri>
233    </address>
234  </author>
235
236  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
237  <workgroup>HTTPbis Working Group</workgroup>
238
239<abstract>
240<t>
241   The Hypertext Transfer Protocol (HTTP) is an application-level
242   protocol for distributed, collaborative, hypermedia information
243   systems. HTTP has been in use by the World Wide Web global information
244   initiative since 1990. This document is Part 2 of the seven-part specification
245   that defines the protocol referred to as "HTTP/1.1" and, taken together,
246   obsoletes RFC 2616.  Part 2 defines the semantics of HTTP messages
247   as expressed by request methods, request-header fields, response status codes,
248   and response-header fields.
249</t>
250</abstract>
251
252<note title="Editorial Note (To be removed by RFC Editor)">
253  <t>
254    Discussion of this draft should take place on the HTTPBIS working group
255    mailing list (ietf-http-wg@w3.org). The current issues list is
256    at <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/>
257    and related documents (including fancy diffs) can be found at
258    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
259  </t>
260  <t>
261    The changes in this draft are summarized in <xref target="changes.since.12"/>.
262  </t>
263</note>
264</front>
265<middle>
266<section title="Introduction" anchor="introduction">
267<t>
268   This document defines HTTP/1.1 request and response semantics.  Each HTTP
269   message, as defined in &messaging;, is in the form of either a request or
270   a response.  An HTTP server listens on a connection for HTTP requests and
271   responds to each request, in the order received on that connection, with
272   one or more HTTP response messages.  This document defines the commonly
273   agreed upon semantics of the HTTP uniform interface, the intentions defined
274   by each request method, and the various response messages that might be
275   expected as a result of applying that method to the target resource.
276</t>
277<t>
278   This document is currently disorganized in order to minimize the changes
279   between drafts and enable reviewers to see the smaller errata changes.
280   A future draft will reorganize the sections to better reflect the content.
281   In particular, the sections will be ordered according to the typical
282   processing of an HTTP request message (after message parsing): resource
283   mapping, general header fields, methods, request modifiers, response
284   status, and resource metadata.  The current mess reflects how widely
285   dispersed these topics and associated requirements had become in
286   <xref target="RFC2616"/>.
287</t>
288
289<section title="Requirements" anchor="intro.requirements">
290<t>
291   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
292   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
293   document are to be interpreted as described in <xref target="RFC2119"/>.
294</t>
295<t>
296   An implementation is not compliant if it fails to satisfy one or more
297   of the "MUST" or "REQUIRED" level requirements for the protocols it
298   implements. An implementation that satisfies all the "MUST" or "REQUIRED"
299   level and all the "SHOULD" level requirements for its protocols is said
300   to be "unconditionally compliant"; one that satisfies all the "MUST"
301   level requirements but not all the "SHOULD" level requirements for its
302   protocols is said to be "conditionally compliant".
303</t>
304</section>
305
306<section title="Syntax Notation" anchor="notation">
307  <x:anchor-alias value="CR"/>
308  <x:anchor-alias value="DIGIT"/>
309  <x:anchor-alias value="LF"/>
310  <x:anchor-alias value="VCHAR"/>
311  <x:anchor-alias value="WSP"/>
312<t>
313  This specification uses the ABNF syntax defined in &notation; (which
314  extends the syntax defined in <xref target="RFC5234"/> with a list rule).
315  <xref target="collected.abnf"/> shows the collected ABNF, with the list
316  rule expanded.
317</t>
318<t>
319  The following core rules are included by
320  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
321  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
322  DIGIT (decimal 0-9), DQUOTE (double quote),
323  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
324  OCTET (any 8-bit sequence of data), SP (space),
325  VCHAR (any visible USASCII character),
326  and WSP (whitespace).
327</t>
328
329<section title="Core Rules" anchor="core.rules">
330  <x:anchor-alias value="obs-text"/>
331  <x:anchor-alias value="quoted-string"/>
332  <x:anchor-alias value="token"/>
333  <x:anchor-alias value="OWS"/>
334  <x:anchor-alias value="RWS"/>
335<t>
336  The core rules below are defined in &basic-rules;:
337</t>
338<figure><artwork type="abnf2616">
339  <x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in &basic-rules;&gt;
340  <x:ref>token</x:ref>         = &lt;token, defined in &basic-rules;&gt;
341  <x:ref>OWS</x:ref>           = &lt;OWS, defined in &basic-rules;&gt;
342  <x:ref>RWS</x:ref>           = &lt;RWS, defined in &basic-rules;&gt;
343  <x:ref>obs-text</x:ref>      = &lt;obs-text, defined in &basic-rules;&gt;
344</artwork></figure>
345</section>
346
347<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
348  <x:anchor-alias value="absolute-URI"/>
349  <x:anchor-alias value="Accept"/>
350  <x:anchor-alias value="Accept-Charset"/>
351  <x:anchor-alias value="Accept-Encoding"/>
352  <x:anchor-alias value="Accept-Language"/>
353  <x:anchor-alias value="Accept-Ranges"/>
354  <x:anchor-alias value="Age"/>
355  <x:anchor-alias value="Authorization"/>
356  <x:anchor-alias value="comment"/>
357  <x:anchor-alias value="ETag"/>
358  <x:anchor-alias value="Host"/>
359  <x:anchor-alias value="HTTP-date"/>
360  <x:anchor-alias value="If-Match"/>
361  <x:anchor-alias value="If-Modified-Since"/>
362  <x:anchor-alias value="If-None-Match"/>
363  <x:anchor-alias value="If-Range"/>
364  <x:anchor-alias value="If-Unmodified-Since"/>
365  <x:anchor-alias value="partial-URI"/>
366  <x:anchor-alias value="product"/>
367  <x:anchor-alias value="Proxy-Authenticate"/>
368  <x:anchor-alias value="Proxy-Authorization"/>
369  <x:anchor-alias value="Range"/>
370  <x:anchor-alias value="TE"/>
371  <x:anchor-alias value="URI-reference"/>
372  <x:anchor-alias value="Vary"/>
373  <x:anchor-alias value="WWW-Authenticate"/>
374<t>
375  The ABNF rules below are defined in other parts:
376</t>
377<figure><!--Part1--><artwork type="abnf2616">
378  <x:ref>absolute-URI</x:ref>  = &lt;absolute-URI, defined in &uri;&gt;
379  <x:ref>authority</x:ref>     = &lt;authority, 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"/><iref primary="true" item="Grammar" subitem="extension-method"/>
436  <x:ref>Method</x:ref>         = <x:abnf-char-sequence>"OPTIONS"</x:abnf-char-sequence>   ; "OPTIONS", <xref target="OPTIONS"/>
437                 / <x:abnf-char-sequence>"GET"</x:abnf-char-sequence>               ; "GET", <xref target="GET"/>
438                 / <x:abnf-char-sequence>"HEAD"</x:abnf-char-sequence>            ; "HEAD", <xref target="HEAD"/>
439                 / <x:abnf-char-sequence>"POST"</x:abnf-char-sequence>            ; "POST", <xref target="POST"/>
440                 / <x:abnf-char-sequence>"PUT"</x:abnf-char-sequence>               ; "PUT", <xref target="PUT"/>
441                 / <x:abnf-char-sequence>"DELETE"</x:abnf-char-sequence>      ; "DELETE", <xref target="DELETE"/>
442                 / <x:abnf-char-sequence>"TRACE"</x:abnf-char-sequence>         ; "TRACE", <xref target="TRACE"/>
443                 / <x:abnf-char-sequence>"CONNECT"</x:abnf-char-sequence>   ; "CONNECT", <xref target="CONNECT"/>
444                 / <x:ref>extension-method</x:ref>
445  <x:ref>extension-method</x:ref> = <x:ref>token</x:ref>
446</artwork></figure>
447<t>
448   The list of methods allowed by a resource can be specified in an
449   Allow header field (<xref target="header.allow"/>). The status code of the response
450   always notifies the client whether a method is currently allowed on a
451   resource, since the set of allowed methods can change dynamically. An
452   origin server &SHOULD; respond with the status code 405 (Method Not Allowed)
453   if the method is known by the origin server but not allowed for the
454   resource, and 501 (Not Implemented) if the method is
455   unrecognized or not implemented by the origin server. The methods GET
456   and HEAD &MUST; be supported by all general-purpose servers. All other
457   methods are &OPTIONAL;; however, if the above methods are implemented,
458   they &MUST; be implemented with the same semantics as those specified
459   in <xref target="method.definitions"/>.
460</t>
461
462<section title="Method Registry" anchor="method.registry">
463<t>
464  The HTTP Method Registry defines the name space for the Method token in the
465  Request line of an HTTP request.
466</t>
467<t>
468  Registrations &MUST; include the following fields:
469  <list style="symbols">
470    <t>Method Name (see <xref target="method"/>)</t>
471    <t>Safe ("yes" or "no", see <xref target="safe.methods"/>)</t>
472    <t>Pointer to specification text</t>
473  </list>
474</t>
475<t>
476  Values to be added to this name space are subject to IETF review
477  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
478</t>
479<t>
480  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-methods"/>.
481</t>
482
483<section title="Considerations for New Methods" anchor="considerations.for.new.methods">
484<t>
485   When it is necessary to express new semantics for a HTTP request that
486   aren't specific to a single application or media type, and currently defined
487   methods are inadequate, it may be appropriate to register a new method.
488</t>
489<t>
490   HTTP methods are generic; that is, they are potentially applicable to any
491   resource, not just one particular media type, "type" of resource, or
492   application. As such, it is preferred that new HTTP methods be registered
493   in a document that isn't specific to a single application, so that this is
494   clear.
495</t>
496<t>
497   Due to the parsing rules defined in &message-body;, definitions of HTTP
498   methods cannot prohibit the presence of a message-body on either the request
499   or the response message (with responses to HEAD requests being the single
500   exception). Definitions of new methods cannot change this rule, but they can
501   specify that only zero-length bodies (as opposed to absent bodies) are allowed.
502</t>
503<t>
504   New method definitions need to indicate whether they are safe (<xref
505   target="safe.methods"/>) and whether they are idempotent (<xref
506   target="idempotent.methods"/>). They also need to state whether they can be
507   cached (&caching;); in particular what conditions a cache may store the
508   response, and under what conditions such a stored response may be used to
509   satisfy a subsequent request.
510</t>
511</section>
512
513</section>
514</section>
515
516<section title="Request Header Fields" anchor="request.header.fields">
517  <x:anchor-alias value="request-header"/>
518<t>
519   The request-header fields allow the client to pass additional
520   information about the request, and about the client itself, to the
521   server. These fields act as request modifiers, with semantics
522   equivalent to the parameters on a programming language method
523   invocation.
524</t>
525<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="request-header"/>
526  <x:ref>request-header</x:ref> = <x:ref>Accept</x:ref>                   ; &header-accept;
527                 / <x:ref>Accept-Charset</x:ref>           ; &header-accept-charset;
528                 / <x:ref>Accept-Encoding</x:ref>          ; &header-accept-encoding;
529                 / <x:ref>Accept-Language</x:ref>          ; &header-accept-language;
530                 / <x:ref>Authorization</x:ref>            ; &header-authorization;
531                 / <x:ref>Expect</x:ref>                   ; <xref target="header.expect"/>
532                 / <x:ref>From</x:ref>                     ; <xref target="header.from"/>
533                 / <x:ref>Host</x:ref>                     ; &header-host;
534                 / <x:ref>If-Match</x:ref>                 ; &header-if-match;
535                 / <x:ref>If-Modified-Since</x:ref>        ; &header-if-modified-since;
536                 / <x:ref>If-None-Match</x:ref>            ; &header-if-none-match;
537                 / <x:ref>If-Range</x:ref>                 ; &header-if-range;
538                 / <x:ref>If-Unmodified-Since</x:ref>      ; &header-if-unmodified-since;
539                 / <x:ref>Max-Forwards</x:ref>             ; <xref target="header.max-forwards"/>
540                 / <x:ref>Proxy-Authorization</x:ref>      ; &header-proxy-authorization;
541                 / <x:ref>Range</x:ref>                    ; &header-range;
542                 / <x:ref>Referer</x:ref>                  ; <xref target="header.referer"/>
543                 / <x:ref>TE</x:ref>                       ; &header-te;
544                 / <x:ref>User-Agent</x:ref>               ; <xref target="header.user-agent"/>
545</artwork></figure>
546<t>
547   Request-header field names can be extended reliably only in
548   combination with a change in the protocol version. However, new or
549   experimental header fields &MAY; be given the semantics of request-header
550   fields if all parties in the communication recognize them to
551   be request-header fields.
552</t>
553</section>
554
555<section title="Status Code and Reason Phrase" anchor="status.code.and.reason.phrase">
556  <x:anchor-alias value="Reason-Phrase"/>
557  <x:anchor-alias value="Status-Code"/>
558  <x:anchor-alias value="extension-code"/>
559<t>
560   The Status-Code element is a 3-digit integer result code of the
561   attempt to understand and satisfy the request. The status codes listed
562   below are defined in <xref target="status.codes"/>, &p4-status-codes;,
563   &p5-status-codes;, and &p7-status-codes;.
564</t>
565<t>
566   The Reason-Phrase is intended to give a short
567   textual description of the Status-Code. The Status-Code is intended
568   for use by automata and the Reason-Phrase is intended for the human
569   user. The client is not required to examine or display the Reason-Phrase.
570</t>
571<t> 
572   The individual values of the numeric status codes defined for
573   HTTP/1.1, and an example set of corresponding Reason-Phrase values, are
574   presented below. The reason phrases listed here are only
575   recommendations -- they &MAY; be replaced by local equivalents without
576   affecting the protocol.
577</t>
578<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"/>
579  <x:ref>Status-Code</x:ref> =
580       "100"  ; <xref target="status.100"/>: Continue
581     / "101"  ; <xref target="status.101"/>: Switching Protocols
582     / "200"  ; <xref target="status.200"/>: OK
583     / "201"  ; <xref target="status.201"/>: Created
584     / "202"  ; <xref target="status.202"/>: Accepted
585     / "203"  ; <xref target="status.203"/>: Non-Authoritative Information
586     / "204"  ; <xref target="status.204"/>: No Content
587     / "205"  ; <xref target="status.205"/>: Reset Content
588     / "206"  ; &status-206;: Partial Content
589     / "300"  ; <xref target="status.300"/>: Multiple Choices
590     / "301"  ; <xref target="status.301"/>: Moved Permanently
591     / "302"  ; <xref target="status.302"/>: Found
592     / "303"  ; <xref target="status.303"/>: See Other
593     / "304"  ; &status-304;: Not Modified
594     / "305"  ; <xref target="status.305"/>: Use Proxy
595     / "307"  ; <xref target="status.307"/>: Temporary Redirect
596     / "400"  ; <xref target="status.400"/>: Bad Request
597     / "401"  ; &status-401;: Unauthorized
598     / "402"  ; <xref target="status.402"/>: Payment Required
599     / "403"  ; <xref target="status.403"/>: Forbidden
600     / "404"  ; <xref target="status.404"/>: Not Found
601     / "405"  ; <xref target="status.405"/>: Method Not Allowed
602     / "406"  ; <xref target="status.406"/>: Not Acceptable
603     / "407"  ; &status-407;: Proxy Authentication Required
604     / "408"  ; <xref target="status.408"/>: Request Time-out
605     / "409"  ; <xref target="status.409"/>: Conflict
606     / "410"  ; <xref target="status.410"/>: Gone
607     / "411"  ; <xref target="status.411"/>: Length Required
608     / "412"  ; &status-412;: Precondition Failed
609     / "413"  ; <xref target="status.413"/>: Request Entity Too Large
610     / "414"  ; <xref target="status.414"/>: URI Too Long
611     / "415"  ; <xref target="status.415"/>: Unsupported Media Type
612     / "416"  ; &status-416;: Requested range not satisfiable
613     / "417"  ; <xref target="status.417"/>: Expectation Failed
614     / "500"  ; <xref target="status.500"/>: Internal Server Error
615     / "501"  ; <xref target="status.501"/>: Not Implemented
616     / "502"  ; <xref target="status.502"/>: Bad Gateway
617     / "503"  ; <xref target="status.503"/>: Service Unavailable
618     / "504"  ; <xref target="status.504"/>: Gateway Time-out
619     / "505"  ; <xref target="status.505"/>: HTTP Version not supported
620     / <x:ref>extension-code</x:ref>
621
622  <x:ref>extension-code</x:ref> = 3<x:ref>DIGIT</x:ref>
623  <x:ref>Reason-Phrase</x:ref>  = *( <x:ref>WSP</x:ref> / <x:ref>VCHAR</x:ref> / <x:ref>obs-text</x:ref> )
624</artwork></figure>
625<t>
626   HTTP status codes are extensible. HTTP applications are not required
627   to understand the meaning of all registered status codes, though such
628   understanding is obviously desirable. However, applications &MUST;
629   understand the class of any status code, as indicated by the first
630   digit, and treat any unrecognized response as being equivalent to the
631   x00 status code of that class, with the exception that an
632   unrecognized response &MUST-NOT; be cached. For example, if an
633   unrecognized status code of 431 is received by the client, it can
634   safely assume that there was something wrong with its request and
635   treat the response as if it had received a 400 status code. In such
636   cases, user agents &SHOULD; present to the user the representation enclosed
637   with the response, since that representation is likely to include human-readable
638   information which will explain the unusual status.
639</t>
640
641<section title="Status Code Registry" anchor="status.code.registry">
642<t>
643  The HTTP Status Code Registry defines the name space for the Status-Code
644  token in the Status-Line of an HTTP response.
645</t>
646<t>
647  Values to be added to this name space are subject to IETF review
648  (<xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
649</t>
650<t>
651  The registry itself is maintained at <eref target="http://www.iana.org/assignments/http-status-codes"/>.
652</t>
653
654<section title="Considerations for New Status Codes" anchor="considerations.for.new.status.codes">
655<t>
656   When it is necessary to express new semantics for a HTTP response that
657   aren't specific to a single application or media type, and currently defined
658   status codes are inadequate, a new status code can be registered.
659</t>
660<t>
661   HTTP status codes are generic; that is, they are potentially applicable to
662   any resource, not just one particular media type, "type" of resource, or
663   application. As such, it is preferred that new HTTP status codes be
664   registered in a document that isn't specific to a single application, so
665   that this is clear.
666</t>
667<t>
668   Definitions of new HTTP status codes typically explain the request
669   conditions that produce a response containing the status code (e.g.,
670   combinations of request headers and/or method(s)), along with any
671   interactions with response headers (e.g., those that are required, those
672   that modify the semantics of the response).
673</t>
674<t>
675   New HTTP status codes are required to fall under one of the categories
676   defined in <xref target="status.codes"/>. To allow existing parsers to
677   properly handle them, new status codes cannot disallow a response body,
678   although they can mandate a zero-length response body. They can require the
679   presence of one or more particular HTTP response header(s).
680</t>
681<t>
682   Likewise, their definitions can specify that caches are allowed to use
683   heuristics to determine their freshness (see &caching;; by default, it is
684   not allowed), and can define how to determine the resource which they
685   carry a representation for (see <xref
686   target="identifying.response.associated.with.representation"/>; by default,
687   it is anonymous).
688</t>
689</section>
690
691</section>
692
693</section>
694
695<section title="Response Header Fields" anchor="response.header.fields">
696  <x:anchor-alias value="response-header"/>
697<t>
698   The response-header fields allow the server to pass additional
699   information about the response which cannot be placed in the Status-Line.
700   These header fields give information about the server and about
701   further access to the target resource (&effective-request-uri;).
702</t>
703<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="response-header"/>
704  <x:ref>response-header</x:ref> = <x:ref>Accept-Ranges</x:ref>           ; &header-accept-ranges;
705                  / <x:ref>Age</x:ref>                     ; &header-age;
706                  / <x:ref>Allow</x:ref>                   ; <xref target="header.allow"/>
707                  / <x:ref>ETag</x:ref>                    ; &header-etag;
708                  / <x:ref>Location</x:ref>                ; <xref target="header.location"/>
709                  / <x:ref>Proxy-Authenticate</x:ref>      ; &header-proxy-authenticate;
710                  / <x:ref>Retry-After</x:ref>             ; <xref target="header.retry-after"/>
711                  / <x:ref>Server</x:ref>                  ; <xref target="header.server"/>
712                  / <x:ref>Vary</x:ref>                    ; &header-vary;
713                  / <x:ref>WWW-Authenticate</x:ref>        ; &header-www-authenticate;
714</artwork></figure>
715<t>
716   Response-header field names can be extended reliably only in
717   combination with a change in the protocol version. However, new or
718   experimental header fields &MAY; be given the semantics of response-header
719   fields if all parties in the communication recognize them to
720   be response-header fields.
721</t>
722</section>
723
724<section title="Representation" anchor="representation">
725<t>
726   Request and Response messages &MAY; transfer a representation if not otherwise
727   restricted by the request method or response status code. A representation
728   consists of metadata (representation header fields) and data (representation
729   body).  When a complete or partial representation is enclosed in an HTTP message,
730   it is referred to as the payload of the message. HTTP representations
731   are defined in &payload;.
732</t>
733<t>
734   A representation body is only present in a message when a message-body is
735   present, as described in &message-body;. The representation body is obtained
736   from the message-body by decoding any Transfer-Encoding that might
737   have been applied to ensure safe and proper transfer of the message.
738</t>
739
740<section title="Identifying the Resource Associated with a Representation" anchor="identifying.response.associated.with.representation">
741<t>
742   It is sometimes necessary to determine an identifier for the resource
743   associated with a representation.
744</t>
745<t>
746   An HTTP request representation, when present, is always associated with an
747   anonymous (i.e., unidentified) resource.
748</t>
749<t>
750   In the common case, an HTTP response is a representation of the target
751   resource (see &effective-request-uri;). However, this is not always the
752   case. To determine the URI of the resource a response is associated with,
753   the following rules are used (with the first applicable one being selected):
754</t>
755<t><list style="numbers">
756   <t>If the response status code is 200 or 203 and the request method was GET,
757   the response payload is a representation of the target resource.</t>
758   <t>If the response status code is 204, 206, or 304 and the request method was GET
759   or HEAD, the response payload is a partial representation of the target
760   (see &combining-responses;).</t>
761   <t>If the response has a Content-Location header field, and that URI is the same
762   as the effective request URI, the response payload is a representation of the
763   target resource.</t>
764   <t>If the response has a Content-Location header field, and that URI is not the
765   same as the effective request URI, then the response asserts that its
766   payload is a representation of the resource identified by the
767   Content-Location URI. However, such an assertion cannot be trusted unless
768   it can be verified by other means (not defined by HTTP).</t>
769   <t>Otherwise, the response is a representation of an anonymous (i.e.,
770   unidentified) resource.</t>
771</list></t>
772<t>
773  <cref anchor="TODO-req-uri">
774   The comparison function is going to have to be defined somewhere,
775   because we already need to compare URIs for things like cache invalidation.</cref>
776</t>
777</section>
778
779</section>
780
781
782<section title="Method Definitions" anchor="method.definitions">
783<t>
784   The set of common methods for HTTP/1.1 is defined below. Although
785   this set can be expanded, additional methods cannot be assumed to
786   share the same semantics for separately extended clients and servers.
787</t>
788
789<section title="Safe and Idempotent Methods" anchor="safe.and.idempotent">
790
791<section title="Safe Methods" anchor="safe.methods">
792<iref item="Safe Methods" primary="true"/>
793<t>
794   Implementors need to be aware that the software represents the user in
795   their interactions over the Internet, and need to allow
796   the user to be aware of any actions they take which might have an
797   unexpected significance to themselves or others.
798</t>
799<t>
800   In particular, the convention has been established that the GET, HEAD,
801   OPTIONS, and TRACE methods &SHOULD-NOT; have the significance of taking an action
802   other than retrieval. These methods ought to be considered "<x:dfn anchor="safe">safe</x:dfn>".
803   This allows user agents to represent other methods, such as POST, PUT
804   and DELETE, in a special way, so that the user is made aware of the
805   fact that a possibly unsafe action is being requested.
806</t>
807<t>
808   Naturally, it is not possible to ensure that the server does not
809   generate side-effects as a result of performing a GET request; in
810   fact, some dynamic resources consider that a feature. The important
811   distinction here is that the user did not request the side-effects,
812   so therefore cannot be held accountable for them.
813</t>
814</section>
815
816<section title="Idempotent Methods" anchor="idempotent.methods">
817<iref item="Idempotent Methods" primary="true"/>
818<t>
819   Methods can also have the property of "idempotence" in that, aside
820   from error or expiration issues, the intended effect of multiple
821   identical requests is the same as for a single request.
822   The methods PUT, DELETE, and all safe methods are idempotent.
823   It is important to note that idempotence refers only to changes
824   requested by the client: a server is free to change its state due
825   to multiple requests for the purpose of tracking those requests,
826   versioning of results, etc.
827</t>
828</section>
829</section>
830
831<section title="OPTIONS" anchor="OPTIONS">
832  <rdf:Description>
833    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
834  </rdf:Description>
835  <iref primary="true" item="OPTIONS method" x:for-anchor=""/>
836  <iref primary="true" item="Methods" subitem="OPTIONS" x:for-anchor=""/>
837<t>
838   The OPTIONS method represents a request for information about the
839   communication options available on the request/response chain
840   identified by the effective request URI. This method allows the client to
841   determine the options and/or requirements associated with a resource,
842   or the capabilities of a server, without implying a resource action
843   or initiating a resource retrieval.
844</t>
845<t>
846   Responses to this method are not cacheable.
847</t>
848<t>
849   If the OPTIONS request includes a message-body (as indicated by the
850   presence of Content-Length or Transfer-Encoding), then the media type
851   &MUST; be indicated by a Content-Type field. Although this
852   specification does not define any use for such a body, future
853   extensions to HTTP might use the OPTIONS body to make more detailed
854   queries on the server.
855</t>
856<t>
857   If the request-target is an asterisk ("*"), the OPTIONS request is
858   intended to apply to the server in general rather than to a specific
859   resource. Since a server's communication options typically depend on
860   the resource, the "*" request is only useful as a "ping" or "no-op"
861   type of method; it does nothing beyond allowing the client to test
862   the capabilities of the server. For example, this can be used to test
863   a proxy for HTTP/1.1 compliance (or lack thereof).
864</t>
865<t>
866   If the request-target is not an asterisk, the OPTIONS request applies
867   only to the options that are available when communicating with that
868   resource.
869</t>
870<t>
871   A 200 response &SHOULD; include any header fields that indicate
872   optional features implemented by the server and applicable to that
873   resource (e.g., Allow), possibly including extensions not defined by
874   this specification. The response body, if any, &SHOULD; also include
875   information about the communication options. The format for such a
876   body is not defined by this specification, but might be defined by
877   future extensions to HTTP. Content negotiation &MAY; be used to select
878   the appropriate response format. If no response body is included, the
879   response &MUST; include a Content-Length field with a field-value of
880   "0".
881</t>
882<t>
883   The Max-Forwards request-header field &MAY; be used to target a
884   specific proxy in the request chain (see <xref target="header.max-forwards"/>).
885   If no Max-Forwards field is present in the request, then the forwarded
886   request &MUST-NOT; include a Max-Forwards field.
887</t>
888</section>
889
890<section title="GET" anchor="GET">
891  <rdf:Description>
892    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
893  </rdf:Description>
894  <iref primary="true" item="GET method" x:for-anchor=""/>
895  <iref primary="true" item="Methods" subitem="GET" x:for-anchor=""/>
896<t>
897   The GET method means retrieve whatever information (in the form of a
898   representation) currently corresponds to the target resource.
899</t>
900<t>   
901   If the target resource is a data-producing process, it is the
902   produced data which shall be returned as the representation in the response and not
903   the source text of the process, unless that text happens to be the output of
904   the process.
905</t>
906<t>
907   The semantics of the GET method change to a "conditional GET" if the
908   request message includes an If-Modified-Since, If-Unmodified-Since,
909   If-Match, If-None-Match, or If-Range header field. A conditional GET
910   method requests that the representation be transferred only under the
911   circumstances described by the conditional header field(s). The
912   conditional GET method is intended to reduce unnecessary network
913   usage by allowing cached representations to be refreshed without requiring
914   multiple requests or transferring data already held by the client.
915</t>
916<t>
917   The semantics of the GET method change to a "partial GET" if the
918   request message includes a Range header field. A partial GET requests
919   that only part of the representation be transferred, as described in &header-range;.
920   The partial GET method is intended to reduce unnecessary
921   network usage by allowing partially-retrieved representations to be
922   completed without transferring data already held by the client.
923</t>
924<t>
925   The response to a GET request is cacheable and &MAY; be used to satisfy
926   subsequent GET and HEAD requests (see &caching;).
927</t>
928<t>
929   See <xref target="encoding.sensitive.information.in.uris"/> for security considerations when used for forms.
930</t>
931</section>
932
933<section title="HEAD" anchor="HEAD">
934  <rdf:Description>
935    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
936  </rdf:Description>
937  <iref primary="true" item="HEAD method" x:for-anchor=""/>
938  <iref primary="true" item="Methods" subitem="HEAD" x:for-anchor=""/>
939<t>
940   The HEAD method is identical to GET except that the server &MUST-NOT;
941   return a message-body in the response. The metadata contained
942   in the HTTP header fields in response to a HEAD request &SHOULD; be identical
943   to the information sent in response to a GET request. This method can
944   be used for obtaining metadata about the representation implied by the
945   request without transferring the representation body. This method is
946   often used for testing hypertext links for validity, accessibility,
947   and recent modification.
948</t>
949<t>
950   The response to a HEAD request is cacheable and &MAY; be used to satisfy
951   a subsequent HEAD request; see &caching;. It also &MAY; be used to update a previously cached
952   representation from that resource; if the new field values
953   indicate that the cached representation differs from the current representation (as
954   would be indicated by a change in Content-Length, Content-MD5, ETag
955   or Last-Modified), then the cache &MUST; treat the cache entry as
956   stale.
957</t>
958</section>
959
960<section title="POST" anchor="POST">
961  <iref primary="true" item="POST method" x:for-anchor=""/>
962  <iref primary="true" item="Methods" subitem="POST" x:for-anchor=""/>
963<t>
964   The POST method is used to request that the origin server accept the
965   representation enclosed in the request as data to be processed by the
966   target resource. POST is designed to allow a uniform method to cover the
967   following functions:
968  <list style="symbols">
969    <t>
970      Annotation of existing resources;
971    </t>
972    <t>
973        Posting a message to a bulletin board, newsgroup, mailing list,
974        or similar group of articles;
975    </t>
976    <t>
977        Providing a block of data, such as the result of submitting a
978        form, to a data-handling process;
979    </t>
980    <t>
981        Extending a database through an append operation.
982    </t>
983  </list>
984</t>
985<t>
986   The actual function performed by the POST method is determined by the
987   server and is usually dependent on the effective request URI.
988</t>
989<t>
990   The action performed by the POST method might not result in a
991   resource that can be identified by a URI. In this case, either 200
992   (OK) or 204 (No Content) is the appropriate response status code,
993   depending on whether or not the response includes a representation that
994   describes the result.
995</t>
996<t>
997   If a resource has been created on the origin server, the response
998   &SHOULD; be 201 (Created) and contain a representation which describes the
999   status of the request and refers to the new resource, and a Location
1000   header field (see <xref target="header.location"/>).
1001</t>
1002<t>
1003   Responses to POST requests are only cacheable when they
1004   include explicit freshness information (see &p6-explicit;). A
1005   cached POST response with a Content-Location header field
1006   (see &header-content-location;) whose value is the effective
1007   Request URI &MAY; be used to satisfy subsequent GET and HEAD requests.
1008</t>
1009<t>
1010   Note that POST caching is not widely implemented.
1011   However, the 303 (See Other) response can be used to direct the
1012   user agent to retrieve a cacheable resource.
1013</t>
1014</section>
1015
1016<section title="PUT" anchor="PUT">
1017  <iref primary="true" item="PUT method" x:for-anchor=""/>
1018  <iref primary="true" item="Methods" subitem="PUT" x:for-anchor=""/>
1019<t>
1020   The PUT method requests that the enclosed representation be stored at the
1021   effective request URI. If the effective request URI refers to an already
1022   existing resource, the enclosed representation &SHOULD; be considered a
1023   modified version of the one residing on the origin server. Otherwise, if the
1024   effective request URI does not point to an existing resource, and that URI is
1025   capable of being defined as a new resource by the requesting user
1026   agent, the origin server can create the resource with that URI.
1027</t>
1028<t>   
1029   If a new resource is created at the effective request URI, the origin
1030   server &MUST; inform the user agent
1031   via the 201 (Created) response. If an existing resource is modified,
1032   either the 200 (OK) or 204 (No Content) response codes &SHOULD; be sent
1033   to indicate successful completion of the request.
1034</t>
1035<t>   
1036   If the target resource could not be created or modified, an appropriate
1037   error response &SHOULD; be given that reflects the nature of the problem.
1038   The recipient of the representation &MUST-NOT; ignore any Content-*
1039   header fields (headers starting with the prefix "Content-") that it does
1040   not understand or implement
1041   and &MUST; return a 501 (Not Implemented) response in such cases.
1042</t>
1043<t>
1044   If the request passes through a cache that has one or more stored
1045   responses for the effective request URI, those stored responses
1046   &SHOULD; be marked as stale if the response to the PUT request
1047   has a success status code. Responses to the PUT method are
1048   not cacheable.
1049</t>
1050<t>
1051   The fundamental difference between the POST and PUT requests is
1052   reflected in the different meaning of the effective request URI. The URI in a
1053   POST request identifies the resource that will handle the enclosed
1054   representation. That resource might be a data-accepting process, a gateway to
1055   some other protocol, or a document that accepts annotations.
1056   In contrast, the URI in a PUT request identifies the resource for
1057   which enclosed representation is a new or replacement value; the
1058   user agent knows what URI is intended and the server &MUST-NOT; attempt
1059   to apply the request to some other resource.
1060   If the server desires that the request be applied to a different URI,
1061   it &MUST; send a 301 (Moved Permanently) response; the user agent &MAY;
1062   then make its own decision regarding whether or not to redirect the
1063   request.
1064</t>
1065<t>
1066   A single resource &MAY; be identified by many different URIs. For
1067   example, an article might have a URI for identifying "the current
1068   version" which is separate from the URI identifying each particular
1069   version. In this case, a PUT request on a general URI might result in
1070   several other URIs being defined by the origin server.
1071</t>
1072<t>
1073   HTTP/1.1 does not define how a PUT method affects the state of an
1074   origin server.
1075</t>
1076<t>
1077   Header fields in a PUT request that are recognized as representation
1078   metadata &SHOULD; be applied to the resource created or modified by
1079   the PUT.  Unrecognized header fields &SHOULD; be ignored.
1080</t>
1081</section>
1082
1083<section title="DELETE" anchor="DELETE">
1084  <iref primary="true" item="DELETE method" x:for-anchor=""/>
1085  <iref primary="true" item="Methods" subitem="DELETE" x:for-anchor=""/>
1086<t>
1087   The DELETE method requests that the origin server delete the target
1088   resource. This method &MAY; be overridden by
1089   human intervention (or other means) on the origin server. The client cannot
1090   be guaranteed that the operation has been carried out, even if the
1091   status code returned from the origin server indicates that the action
1092   has been completed successfully. However, the server &SHOULD-NOT; 
1093   indicate success unless, at the time the response is given, it
1094   intends to delete the resource or move it to an inaccessible
1095   location.
1096</t>
1097<t>
1098   A successful response &SHOULD; be 200 (OK) if the response includes an
1099   representation describing the status, 202 (Accepted) if the action has not
1100   yet been enacted, or 204 (No Content) if the action has been enacted
1101   but the response does not include a representation.
1102</t>
1103<t>
1104   If the request passes through a cache and the effective request URI
1105   identifies one or more currently cached representations, those entries &SHOULD; be
1106   treated as stale. Responses to the DELETE method are not cacheable.
1107</t>
1108</section>
1109
1110<section title="TRACE" anchor="TRACE">
1111  <rdf:Description>
1112    <safe xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">yes</safe>
1113  </rdf:Description>
1114  <iref primary="true" item="TRACE method" x:for-anchor=""/>
1115  <iref primary="true" item="Methods" subitem="TRACE" x:for-anchor=""/>
1116<t>
1117   The TRACE method is used to invoke a remote, application-layer loop-back
1118   of the request message. The final recipient of the request
1119   &SHOULD; reflect the message received back to the client as the
1120   message-body of a 200 (OK) response. The final recipient is either the
1121   origin server or the first proxy or gateway to receive a Max-Forwards
1122   value of zero (0) in the request (see <xref target="header.max-forwards"/>).
1123   A TRACE request &MUST-NOT; include a message-body.
1124</t>
1125<t>
1126   TRACE allows the client to see what is being received at the other
1127   end of the request chain and use that data for testing or diagnostic
1128   information. The value of the Via header field (&header-via;) is of
1129   particular interest, since it acts as a trace of the request chain.
1130   Use of the Max-Forwards header field allows the client to limit the
1131   length of the request chain, which is useful for testing a chain of
1132   proxies forwarding messages in an infinite loop.
1133</t>
1134<t>
1135   If the request is valid, the response &SHOULD; have a Content-Type of
1136   "message/http" (see &media-type-message-http;) and contain a message-body
1137   that encloses a copy of the entire request message.
1138   Responses to the TRACE method are not cacheable.
1139</t>
1140</section>
1141
1142<section title="CONNECT" anchor="CONNECT">
1143  <iref primary="true" item="CONNECT method" x:for-anchor=""/>
1144  <iref primary="true" item="Methods" subitem="CONNECT" x:for-anchor=""/>
1145<t>
1146   The CONNECT method is used with a proxy to dynamically switch
1147   the connection to a tunnel.
1148</t>
1149<t>
1150   When using CONNECT, the request-target &MUST; be an authority; i.e.,
1151   the host name and port number destination of the requested connection
1152   separated by a colon:
1153</t>
1154
1155<figure><artwork type="example">
1156    CONNECT server.example.com:80 HTTP/1.1
1157    Host: server.example.com:80
1158</artwork></figure>
1159
1160<t>
1161   Other HTTP mechanisms can be used normally with the CONNECT method --
1162   except end-to-end protocol Upgrade requests, since the
1163   tunnel must be established first.
1164</t>
1165<t>
1166   For example, proxy authentication might be used to establish the
1167   authority to create a tunnel:
1168</t>
1169
1170<figure><artwork type="example">
1171    CONNECT server.example.com:80 HTTP/1.1
1172    Host: server.example.com:80
1173    Proxy-Authorization: basic aGVsbG86d29ybGQ=
1174</artwork></figure>
1175
1176<t>
1177   Like any other pipelined HTTP/1.1 request, data to be tunnel may be
1178   sent immediately after the blank line. The usual caveats also apply:
1179   data may be discarded if the eventual response is negative, and the
1180   connection may be reset with no response if more than one TCP segment
1181   is outstanding.
1182</t>
1183
1184<section title="Establishing a Tunnel with CONNECT">
1185<t>
1186   Any successful (2xx) response to a CONNECT request indicates that the
1187   proxy has established a connection to the requested host and port,
1188   and has switched to tunneling the current connection to that server
1189   connection.
1190</t>
1191<t>
1192   It may be the case that the proxy itself can only reach the requested
1193   origin server through another proxy.  In this case, the first proxy
1194   &SHOULD; make a CONNECT request of that next proxy, requesting a tunnel
1195   to the authority.  A proxy &MUST-NOT; respond with any 2xx status code
1196   unless it has either a direct or tunnel connection established to the
1197   authority.
1198</t>
1199<t>
1200   An origin server which receives a CONNECT request for itself &MAY;
1201   respond with a 2xx status code to indicate that a connection is
1202   established.
1203</t>
1204<t>
1205   If at any point either one of the peers gets disconnected, any
1206   outstanding data that came from that peer will be passed to the other
1207   one, and after that also the other connection will be terminated by
1208   the proxy. If there is outstanding data to that peer undelivered,
1209   that data will be discarded.
1210</t>
1211
1212</section>
1213</section>
1214</section>
1215
1216
1217<section title="Status Code Definitions" anchor="status.codes">
1218<t>
1219   Each Status-Code is described below, including any metadata required
1220   in the response.
1221</t>
1222
1223<section title="Informational 1xx" anchor="status.1xx">
1224<t>
1225   This class of status code indicates a provisional response,
1226   consisting only of the Status-Line and optional header fields, and is
1227   terminated by an empty line. There are no required header fields for this
1228   class of status code. Since HTTP/1.0 did not define any 1xx status
1229   codes, servers &MUST-NOT; send a 1xx response to an HTTP/1.0 client
1230   except under experimental conditions.
1231</t>
1232<t>
1233   A client &MUST; be prepared to accept one or more 1xx status responses
1234   prior to a regular response, even if the client does not expect a 100
1235   (Continue) status message. Unexpected 1xx status responses &MAY; be
1236   ignored by a user agent.
1237</t>
1238<t>
1239   Proxies &MUST; forward 1xx responses, unless the connection between the
1240   proxy and its client has been closed, or unless the proxy itself
1241   requested the generation of the 1xx response. (For example, if a
1242   proxy adds a "Expect: 100-continue" field when it forwards a request,
1243   then it need not forward the corresponding 100 (Continue)
1244   response(s).)
1245</t>
1246
1247<section title="100 Continue" anchor="status.100">
1248  <iref primary="true" item="100 Continue (status code)" x:for-anchor=""/>
1249  <iref primary="true" item="Status Codes" subitem="100 Continue" x:for-anchor=""/>
1250<t>
1251   The client &SHOULD; continue with its request. This interim response is
1252   used to inform the client that the initial part of the request has
1253   been received and has not yet been rejected by the server. The client
1254   &SHOULD; continue by sending the remainder of the request or, if the
1255   request has already been completed, ignore this response. The server
1256   &MUST; send a final response after the request has been completed. See
1257   &use100; for detailed discussion of the use and handling of this
1258   status code.
1259</t>
1260</section>
1261
1262<section title="101 Switching Protocols" anchor="status.101">
1263  <iref primary="true" item="101 Switching Protocols (status code)" x:for-anchor=""/>
1264  <iref primary="true" item="Status Codes" subitem="101 Switching Protocols" x:for-anchor=""/>
1265<t>
1266   The server understands and is willing to comply with the client's
1267   request, via the Upgrade message header field (&header-upgrade;), for a
1268   change in the application protocol being used on this connection. The
1269   server will switch protocols to those defined by the response's
1270   Upgrade header field immediately after the empty line which
1271   terminates the 101 response.
1272</t>
1273<t>
1274   The protocol &SHOULD; be switched only when it is advantageous to do
1275   so. For example, switching to a newer version of HTTP is advantageous
1276   over older versions, and switching to a real-time, synchronous
1277   protocol might be advantageous when delivering resources that use
1278   such features.
1279</t>
1280</section>
1281</section>
1282
1283<section title="Successful 2xx" anchor="status.2xx">
1284<t>
1285   This class of status code indicates that the client's request was
1286   successfully received, understood, and accepted.
1287</t>
1288
1289<section title="200 OK" anchor="status.200">
1290  <iref primary="true" item="200 OK (status code)" x:for-anchor=""/>
1291  <iref primary="true" item="Status Codes" subitem="200 OK" x:for-anchor=""/>
1292<t>
1293   The request has succeeded. The payload returned with the response
1294   is dependent on the method used in the request, for example:
1295  <list style="hanging">
1296    <t hangText="GET">
1297          a representation of the target resource is sent in the response;
1298    </t>
1299    <t hangText="HEAD">
1300          the same representation as GET, except without the message-body;
1301    </t>
1302    <t hangText="POST">
1303      a representation describing or containing the result of the action;
1304    </t>
1305    <t hangText="TRACE">
1306      a representation containing the request message as received by the
1307      end server.
1308    </t>
1309  </list>
1310</t>
1311<t>
1312   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1313   freshness for 200 responses.
1314</t>
1315</section>
1316
1317<section title="201 Created" anchor="status.201">
1318  <iref primary="true" item="201 Created (status code)" x:for-anchor=""/>
1319  <iref primary="true" item="Status Codes" subitem="201 Created" x:for-anchor=""/>
1320<t>
1321   The request has been fulfilled and has resulted in a new resource being
1322   created. The newly created resource can be referenced by the URI(s)
1323   returned in the payload of the response, with the most specific URI
1324   for the resource given by a Location header field. The response
1325   &SHOULD; include a payload containing a list of resource
1326   characteristics and location(s) from which the user or user agent can
1327   choose the one most appropriate. The payload format is specified by
1328   the media type given in the Content-Type header field. The origin
1329   server &MUST; create the resource before returning the 201 status code.
1330   If the action cannot be carried out immediately, the server &SHOULD;
1331   respond with 202 (Accepted) response instead.
1332</t>
1333<t>
1334   A 201 response &MAY; contain an ETag response header field indicating
1335   the current value of the entity-tag for the representation of the resource
1336   just created (see &header-etag;).
1337</t>
1338</section>
1339
1340<section title="202 Accepted" anchor="status.202">
1341  <iref primary="true" item="202 Accepted (status code)" x:for-anchor=""/>
1342  <iref primary="true" item="Status Codes" subitem="202 Accepted" x:for-anchor=""/>
1343<t>
1344   The request has been accepted for processing, but the processing has
1345   not been completed.  The request might or might not eventually be
1346   acted upon, as it might be disallowed when processing actually takes
1347   place. There is no facility for re-sending a status code from an
1348   asynchronous operation such as this.
1349</t>
1350<t>
1351   The 202 response is intentionally non-committal. Its purpose is to
1352   allow a server to accept a request for some other process (perhaps a
1353   batch-oriented process that is only run once per day) without
1354   requiring that the user agent's connection to the server persist
1355   until the process is completed. The representation returned with this
1356   response &SHOULD; include an indication of the request's current status
1357   and either a pointer to a status monitor or some estimate of when the
1358   user can expect the request to be fulfilled.
1359</t>
1360</section>
1361
1362<section title="203 Non-Authoritative Information" anchor="status.203">
1363  <iref primary="true" item="203 Non-Authoritative Information (status code)" x:for-anchor=""/>
1364  <iref primary="true" item="Status Codes" subitem="203 Non-Authoritative Information" x:for-anchor=""/>
1365<t>
1366   The returned metadata in the header fields is not the
1367   definitive set as available from the origin server, but is gathered
1368   from a local or a third-party copy. The set presented &MAY; be a subset
1369   or superset of the original version. For example, including local
1370   annotation information about the resource might result in a superset
1371   of the metadata known by the origin server. Use of this
1372   response code is not required and is only appropriate when the
1373   response would otherwise be 200 (OK).
1374</t>
1375<t>
1376   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1377   freshness for 203 responses.
1378</t>
1379
1380</section>
1381
1382<section title="204 No Content" anchor="status.204">
1383  <iref primary="true" item="204 No Content (status code)" x:for-anchor=""/>
1384  <iref primary="true" item="Status Codes" subitem="204 No Content" x:for-anchor=""/>
1385<t>
1386   The server has successfully fulfilled the request, but there is no
1387   additional content to return in the response payload body.  The
1388   resource metadata and representation metadata in the response message's
1389   header fields refer to the target resource
1390   and its current representation, respectively, after the requested action.
1391   For example, if a 204 status code is received in response to a PUT
1392   and the response contains an ETag header field, then the value of
1393   that field is the current entity-tag for the representation that
1394   was successfully PUT.
1395</t>
1396<t>
1397   If the client is a user agent, it &SHOULD-NOT; change its document view
1398   from that which caused the request to be sent. This response is
1399   primarily intended to allow input for actions to take place without
1400   causing a change to the user agent's active document view, although
1401   any new or updated metadata &SHOULD; be applied to the document
1402   currently in the user agent's active view.
1403</t>
1404<t>
1405   The 204 response &MUST-NOT; include a message-body, and thus is always
1406   terminated by the first empty line after the header fields.
1407</t>
1408</section>
1409
1410<section title="205 Reset Content" anchor="status.205">
1411  <iref primary="true" item="205 Reset Content (status code)" x:for-anchor=""/>
1412  <iref primary="true" item="Status Codes" subitem="205 Reset Content" x:for-anchor=""/>
1413<t>
1414   The server has fulfilled the request and the user agent &SHOULD; reset
1415   the document view which caused the request to be sent. This response
1416   is primarily intended to allow input for actions to take place via
1417   user input, followed by a clearing of the form in which the input is
1418   given so that the user can easily initiate another input action.
1419</t>
1420<t>   
1421   The message-body included with the response &MUST; be empty. Note that
1422   receivers still need to parse the response according to the algorithm defined
1423   in &message-body;.
1424</t>
1425</section>
1426
1427<section title="206 Partial Content" anchor="status.206">
1428  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
1429  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
1430  <rdf:Description>
1431    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1432  </rdf:Description>
1433<t>
1434   The server has fulfilled the partial GET request for the resource
1435   and the enclosed payload is a partial representation as defined in &status-206;.
1436</t>
1437<t>
1438   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1439   freshness for 206 responses.
1440</t>
1441</section>
1442</section>
1443
1444<section title="Redirection 3xx" anchor="status.3xx">
1445<t>
1446   This class of status code indicates that further action needs to be
1447   taken by the user agent in order to fulfill the request.  The action
1448   required &MAY; be carried out by the user agent without interaction
1449   with the user if and only if the method used in the second request is
1450   known to be "safe", as defined in <xref target="safe.methods"/>.
1451   A client &SHOULD; detect infinite redirection loops, since such loops
1452   generate network traffic for each redirection.
1453</t>
1454<x:note>
1455  <t>
1456    <x:h>Note:</x:h> An earlier version of this specification recommended a
1457    maximum of five redirections (<xref target="RFC2068" x:fmt="," x:sec="10.3"/>).
1458    Content developers need to be aware that some clients might
1459    implement such a fixed limitation.
1460  </t>
1461</x:note>
1462
1463<section title="300 Multiple Choices" anchor="status.300">
1464  <iref primary="true" item="300 Multiple Choices (status code)" x:for-anchor=""/>
1465  <iref primary="true" item="Status Codes" subitem="300 Multiple Choices" x:for-anchor=""/>
1466<t>
1467   The target resource has more than one
1468   representation, each with its own specific location, and agent-driven
1469   negotiation information (&content-negotiation;) is being provided so that
1470   the user (or user agent) can select a preferred representation by
1471   redirecting its request to that location.
1472</t>
1473<t>
1474   Unless it was a HEAD request, the response &SHOULD; include a representation
1475   containing a list of representation metadata and location(s) from
1476   which the user or user agent can choose the one most appropriate. The
1477   data format is specified by the media type given in the Content-Type
1478   header field. Depending upon the format and the capabilities of
1479   the user agent, selection of the most appropriate choice &MAY; be
1480   performed automatically. However, this specification does not define
1481   any standard for such automatic selection.
1482</t>
1483<t>
1484   If the server has a preferred choice of representation, it &SHOULD;
1485   include the specific URI for that representation in the Location
1486   field; user agents &MAY; use the Location field value for automatic
1487   redirection.
1488</t>
1489<t>
1490   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1491   freshness for 300 responses.
1492</t>
1493
1494</section>
1495
1496<section title="301 Moved Permanently" anchor="status.301">
1497  <iref primary="true" item="301 Moved Permanently (status code)" x:for-anchor=""/>
1498  <iref primary="true" item="Status Codes" subitem="301 Moved Permanently" x:for-anchor=""/>
1499<t>
1500   The target resource has been assigned a new permanent URI and any
1501   future references to this resource &SHOULD; use one of the returned
1502   URIs.  Clients with link editing capabilities ought to automatically
1503   re-link references to the effective request URI to one or more of the new
1504   references returned by the server, where possible.
1505</t>
1506<t>
1507   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
1508   freshness for 301 responses.
1509</t>
1510<t>
1511   The new permanent URI &SHOULD; be given by the Location field in the
1512   response. Unless the request method was HEAD, the representation of the
1513   response &SHOULD; contain a short hypertext note with a hyperlink to
1514   the new URI(s).
1515</t>
1516<t>
1517   If the 301 status code is received in response to a request method
1518   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1519   then the request &MAY; be automatically redirected by the user agent without
1520   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1521   request unless it can be confirmed by the user, since this might
1522   change the conditions under which the request was issued.
1523</t>
1524<x:note>
1525  <t>
1526    <x:h>Note:</x:h> When automatically redirecting a POST request after
1527    receiving a 301 status code, some existing HTTP/1.0 user agents
1528    will erroneously change it into a GET request.
1529  </t>
1530</x:note>
1531</section>
1532
1533<section title="302 Found" anchor="status.302">
1534  <iref primary="true" item="302 Found (status code)" x:for-anchor=""/>
1535  <iref primary="true" item="Status Codes" subitem="302 Found" x:for-anchor=""/>
1536<t>
1537   The target resource resides temporarily under a different URI.
1538   Since the redirection might be altered on occasion, the client &SHOULD;
1539   continue to use the effective request URI for future requests.
1540</t>
1541<t>
1542   The temporary URI &SHOULD; be given by the Location field in the
1543   response. Unless the request method was HEAD, the representation of the
1544   response &SHOULD; contain a short hypertext note with a hyperlink to
1545   the new URI(s).
1546</t>
1547<t>
1548   If the 302 status code is received in response to a request method
1549   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1550   then the request &MAY; be automatically redirected by the user agent without
1551   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1552   request unless it can be confirmed by the user, since this might
1553   change the conditions under which the request was issued.
1554</t>
1555<x:note>
1556  <t>
1557    <x:h>Note:</x:h> HTTP/1.0 (<xref target="RFC1945" x:fmt="," x:sec="9.3"/>)
1558    and the first version of HTTP/1.1 (<xref target="RFC2068" x:fmt="," x:sec ="10.3.3"/>)
1559    specify that the client is not allowed to change the method on the
1560    redirected request.  However, most existing user agent implementations
1561    treat 302 as if it were a 303 response, performing a GET on the Location
1562    field-value regardless of the original request method. Therefore, a
1563    previous version of this specification
1564    (<xref target="RFC2616" x:fmt="," x:sec="10.3.3"/>) has added the
1565    status codes
1566    <xref target="status.303" format="none">303</xref> and
1567    <xref target="status.307" format="none">307</xref> for servers that wish
1568    to make unambiguously clear which kind of reaction is expected of the
1569    client.
1570  </t>
1571</x:note>
1572</section>
1573
1574<section title="303 See Other" anchor="status.303">
1575  <iref primary="true" item="303 See Other (status code)" x:for-anchor=""/>
1576  <iref primary="true" item="Status Codes" subitem="303 See Other" x:for-anchor=""/>
1577<t>
1578   The server directs the user agent to a different resource, indicated
1579   by a URI in the Location header field, that provides an indirect
1580   response to the original request.  The user agent &MAY; perform a GET
1581   request on the URI in the Location field in order to obtain a
1582   representation corresponding to the response, be redirected again,
1583   or end with an error status.  The Location URI is not a substitute
1584   reference for the effective request URI.
1585</t>
1586<t>
1587   The 303 status code is generally applicable to any HTTP method.  It is
1588   primarily used to allow the output of a POST action to redirect
1589   the user agent to a selected resource, since doing so provides the
1590   information corresponding to the POST response in a form that
1591   can be separately identified, bookmarked, and cached independent
1592   of the original request.
1593</t>
1594<t>
1595   A 303 response to a GET request indicates that the requested
1596   resource does not have a representation of its own that can be
1597   transferred by the server over HTTP.  The Location URI indicates a
1598   resource that is descriptive of the target resource, such that the
1599   follow-on representation might be useful to recipients without
1600   implying that it adequately represents the target resource.
1601   Note that answers to the questions of what can be represented, what
1602   representations are adequate, and what might be a useful description
1603   are outside the scope of HTTP and thus entirely determined by the
1604   URI owner(s).
1605</t>
1606<t>
1607   Except for responses to a HEAD request, the representation of a 303
1608   response &SHOULD; contain a short hypertext note with a hyperlink
1609   to the Location URI.
1610</t>
1611</section>
1612
1613<section title="304 Not Modified" anchor="status.304">
1614  <iref primary="true" item="304 Not Modified (status code)" x:for-anchor=""/>
1615  <iref primary="true" item="Status Codes" subitem="304 Not Modified" x:for-anchor=""/>
1616  <rdf:Description>
1617    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1618  </rdf:Description>
1619<t>
1620   The response to the request has not been modified since the conditions
1621   indicated by the client's conditional GET request, as defined in &status-304;.
1622</t>
1623</section>
1624
1625<section title="305 Use Proxy" anchor="status.305">
1626  <iref primary="true" item="305 Use Proxy (status code)" x:for-anchor=""/>
1627  <iref primary="true" item="Status Codes" subitem="305 Use Proxy" x:for-anchor=""/>
1628<t>
1629   The 305 status code was defined in a previous version of this specification
1630   (see <xref target="changes.from.rfc.2616"/>), and is now deprecated.
1631</t>
1632</section>
1633
1634<section title="306 (Unused)" anchor="status.306">
1635  <iref primary="true" item="306 (Unused) (status code)" x:for-anchor=""/>
1636  <iref primary="true" item="Status Codes" subitem="306 (Unused)" x:for-anchor=""/>
1637<t>
1638   The 306 status code was used in a previous version of the
1639   specification, is no longer used, and the code is reserved.
1640</t>
1641</section>
1642
1643<section title="307 Temporary Redirect" anchor="status.307">
1644  <iref primary="true" item="307 Temporary Redirect (status code)" x:for-anchor=""/>
1645  <iref primary="true" item="Status Codes" subitem="307 Temporary Redirect" x:for-anchor=""/>
1646<t>
1647   The target resource resides temporarily under a different URI.
1648   Since the redirection can change over time, the client &SHOULD;
1649   continue to use the effective request URI for future requests.
1650</t>
1651<t>
1652   The temporary URI &SHOULD; be given by the Location field in the
1653   response. Unless the request method was HEAD, the representation of the
1654   response &SHOULD; contain a short hypertext note with a hyperlink to
1655   the new URI(s), since many pre-HTTP/1.1 user agents do not
1656   understand the 307 status code. Therefore, the note &SHOULD; contain the
1657   information necessary for a user to repeat the original request on
1658   the new URI.
1659</t>
1660<t>
1661   If the 307 status code is received in response to a request method
1662   that is known to be "safe", as defined in <xref target="safe.methods"/>,
1663   then the request &MAY; be automatically redirected by the user agent without
1664   confirmation.  Otherwise, the user agent &MUST-NOT; automatically redirect the
1665   request unless it can be confirmed by the user, since this might
1666   change the conditions under which the request was issued.
1667</t>
1668</section>
1669</section>
1670
1671<section title="Client Error 4xx" anchor="status.4xx">
1672<t>
1673   The 4xx class of status code is intended for cases in which the
1674   client seems to have erred. Except when responding to a HEAD request,
1675   the server &SHOULD; include a representation containing an explanation of the
1676   error situation, and whether it is a temporary or permanent
1677   condition. These status codes are applicable to any request method.
1678   User agents &SHOULD; display any included representation to the user.
1679</t>
1680<t>
1681   If the client is sending data, a server implementation using TCP
1682   &SHOULD; be careful to ensure that the client acknowledges receipt of
1683   the packet(s) containing the response, before the server closes the
1684   input connection. If the client continues sending data to the server
1685   after the close, the server's TCP stack will send a reset packet to
1686   the client, which might erase the client's unacknowledged input buffers
1687   before they can be read and interpreted by the HTTP application.
1688</t>
1689
1690<section title="400 Bad Request" anchor="status.400">
1691  <iref primary="true" item="400 Bad Request (status code)" x:for-anchor=""/>
1692  <iref primary="true" item="Status Codes" subitem="400 Bad Request" x:for-anchor=""/>
1693<t>
1694   The request could not be understood by the server due to malformed
1695   syntax. The client &SHOULD-NOT; repeat the request without
1696   modifications.
1697</t>
1698</section>
1699
1700<section title="401 Unauthorized" anchor="status.401">
1701  <iref primary="true" item="401 Unauthorized (status code)" x:for-anchor=""/>
1702  <iref primary="true" item="Status Codes" subitem="401 Unauthorized" x:for-anchor=""/>
1703  <rdf:Description>
1704    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part7</redirects-to>
1705  </rdf:Description>
1706<t>
1707   The request requires user authentication (see &status-401;).
1708</t>
1709</section>
1710
1711<section title="402 Payment Required" anchor="status.402">
1712  <iref primary="true" item="402 Payment Required (status code)" x:for-anchor=""/>
1713  <iref primary="true" item="Status Codes" subitem="402 Payment Required" x:for-anchor=""/>
1714<t>
1715   This code is reserved for future use.
1716</t>
1717</section>
1718
1719<section title="403 Forbidden" anchor="status.403">
1720  <iref primary="true" item="403 Forbidden (status code)" x:for-anchor=""/>
1721  <iref primary="true" item="Status Codes" subitem="403 Forbidden" x:for-anchor=""/>
1722<t>
1723   The server understood the request, but is refusing to fulfill it.
1724   Authorization will not help and the request &SHOULD-NOT;  be repeated.
1725   If the request method was not HEAD and the server wishes to make
1726   public why the request has not been fulfilled, it &SHOULD; describe the
1727   reason for the refusal in the representation.  If the server does not wish to
1728   make this information available to the client, the status code 404
1729   (Not Found) can be used instead.
1730</t>
1731</section>
1732
1733<section title="404 Not Found" anchor="status.404">
1734  <iref primary="true" item="404 Not Found (status code)" x:for-anchor=""/>
1735  <iref primary="true" item="Status Codes" subitem="404 Not Found" x:for-anchor=""/>
1736<t>
1737   The server has not found anything matching the effective request URI. No
1738   indication is given of whether the condition is temporary or
1739   permanent. The 410 (Gone) status code &SHOULD; be used if the server
1740   knows, through some internally configurable mechanism, that an old
1741   resource is permanently unavailable and has no forwarding address.
1742   This status code is commonly used when the server does not wish to
1743   reveal exactly why the request has been refused, or when no other
1744   response is applicable.
1745</t>
1746</section>
1747
1748<section title="405 Method Not Allowed" anchor="status.405">
1749  <iref primary="true" item="405 Method Not Allowed (status code)" x:for-anchor=""/>
1750  <iref primary="true" item="Status Codes" subitem="405 Method Not Allowed" x:for-anchor=""/>
1751<t>
1752   The method specified in the Request-Line is not allowed for the target
1753   resource. The response &MUST; include an
1754   Allow header field containing a list of valid methods for the requested
1755   resource.
1756</t>
1757</section>
1758
1759<section title="406 Not Acceptable" anchor="status.406">
1760  <iref primary="true" item="406 Not Acceptable (status code)" x:for-anchor=""/>
1761  <iref primary="true" item="Status Codes" subitem="406 Not Acceptable" x:for-anchor=""/>
1762<t>
1763   The resource identified by the request is only capable of generating
1764   response representations which have content characteristics not acceptable
1765   according to the accept header fields sent in the request.
1766</t>
1767<t>
1768   Unless it was a HEAD request, the response &SHOULD; include a representation
1769   containing a list of available representation characteristics and location(s)
1770   from which the user or user agent can choose the one most
1771   appropriate. The data format is specified by the media type given
1772   in the Content-Type header field. Depending upon the format and the
1773   capabilities of the user agent, selection of the most appropriate
1774   choice &MAY; be performed automatically. However, this specification
1775   does not define any standard for such automatic selection.
1776</t>
1777<x:note>
1778  <t>
1779    <x:h>Note:</x:h> HTTP/1.1 servers are allowed to return responses which are
1780    not acceptable according to the accept header fields sent in the
1781    request. In some cases, this might even be preferable to sending a
1782    406 response. User agents are encouraged to inspect the header fields of
1783    an incoming response to determine if it is acceptable.
1784  </t>
1785</x:note>
1786<t>
1787   If the response could be unacceptable, a user agent &SHOULD;
1788   temporarily stop receipt of more data and query the user for a
1789   decision on further actions.
1790</t>
1791</section>
1792
1793<section title="407 Proxy Authentication Required" anchor="status.407">
1794  <iref primary="true" item="407 Proxy Authentication Required (status code)" x:for-anchor=""/>
1795  <iref primary="true" item="Status Codes" subitem="407 Proxy Authentication Required" x:for-anchor=""/>
1796<t>
1797   This code is similar to 401 (Unauthorized), but indicates that the
1798   client must first authenticate itself with the proxy (see &status-407;).
1799</t>
1800</section>
1801
1802<section title="408 Request Timeout" anchor="status.408">
1803  <iref primary="true" item="408 Request Timeout (status code)" x:for-anchor=""/>
1804  <iref primary="true" item="Status Codes" subitem="408 Request Timeout" x:for-anchor=""/>
1805<t>
1806   The client did not produce a request within the time that the server
1807   was prepared to wait. The client &MAY; repeat the request without
1808   modifications at any later time.
1809</t>
1810</section>
1811
1812<section title="409 Conflict" anchor="status.409">
1813  <iref primary="true" item="409 Conflict (status code)" x:for-anchor=""/>
1814  <iref primary="true" item="Status Codes" subitem="409 Conflict" x:for-anchor=""/>
1815<t>
1816   The request could not be completed due to a conflict with the current
1817   state of the resource. This code is only allowed in situations where
1818   it is expected that the user might be able to resolve the conflict
1819   and resubmit the request. The response body &SHOULD; include enough
1820   information for the user to recognize the source of the conflict.
1821   Ideally, the response representation would include enough information for the
1822   user or user agent to fix the problem; however, that might not be
1823   possible and is not required.
1824</t>
1825<t>
1826   Conflicts are most likely to occur in response to a PUT request. For
1827   example, if versioning were being used and the representation being PUT
1828   included changes to a resource which conflict with those made by an
1829   earlier (third-party) request, the server might use the 409 response
1830   to indicate that it can't complete the request. In this case, the
1831   response representation would likely contain a list of the differences
1832   between the two versions in a format defined by the response
1833   Content-Type.
1834</t>
1835</section>
1836
1837<section title="410 Gone" anchor="status.410">
1838  <iref primary="true" item="410 Gone (status code)" x:for-anchor=""/>
1839  <iref primary="true" item="Status Codes" subitem="410 Gone" x:for-anchor=""/>
1840<t>
1841   The target resource is no longer available at the server and no
1842   forwarding address is known. This condition is expected to be
1843   considered permanent. Clients with link editing capabilities &SHOULD;
1844   delete references to the effective request URI after user approval. If the
1845   server does not know, or has no facility to determine, whether or not
1846   the condition is permanent, the status code 404 (Not Found) &SHOULD; be
1847   used instead.
1848</t>
1849<t>
1850   The 410 response is primarily intended to assist the task of web
1851   maintenance by notifying the recipient that the resource is
1852   intentionally unavailable and that the server owners desire that
1853   remote links to that resource be removed. Such an event is common for
1854   limited-time, promotional services and for resources belonging to
1855   individuals no longer working at the server's site. It is not
1856   necessary to mark all permanently unavailable resources as "gone" or
1857   to keep the mark for any length of time -- that is left to the
1858   discretion of the server owner.
1859</t>
1860<t>
1861   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine freshness
1862   for 410 responses.
1863</t>
1864
1865</section>
1866
1867<section title="411 Length Required" anchor="status.411">
1868  <iref primary="true" item="411 Length Required (status code)" x:for-anchor=""/>
1869  <iref primary="true" item="Status Codes" subitem="411 Length Required" x:for-anchor=""/>
1870<t>
1871   The server refuses to accept the request without a defined Content-Length.
1872   The client &MAY; repeat the request if it adds a valid
1873   Content-Length header field containing the length of the message-body
1874   in the request message.
1875</t>
1876</section>
1877
1878<section title="412 Precondition Failed" anchor="status.412">
1879  <iref primary="true" item="412 Precondition Failed (status code)" x:for-anchor=""/>
1880  <iref primary="true" item="Status Codes" subitem="412 Precondition Failed" x:for-anchor=""/>
1881  <rdf:Description>
1882    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part4</redirects-to>
1883  </rdf:Description>
1884<t>
1885   The precondition given in one or more of the request-header fields
1886   evaluated to false when it was tested on the server, as defined in
1887   &status-412;.
1888</t>
1889</section>
1890
1891<section title="413 Request Entity Too Large" anchor="status.413">
1892  <iref primary="true" item="413 Request Entity Too Large (status code)" x:for-anchor=""/>
1893  <iref primary="true" item="Status Codes" subitem="413 Request Entity Too Large" x:for-anchor=""/>
1894<t>
1895   The server is refusing to process a request because the request
1896   representation is larger than the server is willing or able to process. The
1897   server &MAY; close the connection to prevent the client from continuing
1898   the request.
1899</t>
1900<t>
1901   If the condition is temporary, the server &SHOULD; include a Retry-After
1902   header field to indicate that it is temporary and after what
1903   time the client &MAY; try again.
1904</t>
1905</section>
1906
1907<section title="414 URI Too Long" anchor="status.414">
1908  <iref primary="true" item="414 URI Too Long (status code)" x:for-anchor=""/>
1909  <iref primary="true" item="Status Codes" subitem="414 URI Too Long" x:for-anchor=""/>
1910<t>
1911   The server is refusing to service the request because the effective request URI
1912   is longer than the server is willing to interpret. This rare
1913   condition is only likely to occur when a client has improperly
1914   converted a POST request to a GET request with long query
1915   information, when the client has descended into a URI "black hole" of
1916   redirection (e.g., a redirected URI prefix that points to a suffix of
1917   itself), or when the server is under attack by a client attempting to
1918   exploit security holes present in some servers using fixed-length
1919   buffers for reading or manipulating the effective request URI.
1920</t>
1921</section>
1922
1923<section title="415 Unsupported Media Type" anchor="status.415">
1924  <iref primary="true" item="415 Unsupported Media Type (status code)" x:for-anchor=""/>
1925  <iref primary="true" item="Status Codes" subitem="415 Unsupported Media Type" x:for-anchor=""/>
1926<t>
1927   The server is refusing to service the request because the representation of
1928   the request is in a format not supported by the target resource
1929   for the requested method.
1930</t>
1931</section>
1932
1933<section title="416 Requested Range Not Satisfiable" anchor="status.416">
1934  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
1935  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
1936  <rdf:Description>
1937    <redirects-to xmlns="urn:ietf:id:draft-ietf-httpbis-p2-semantics#">Part5</redirects-to>
1938  </rdf:Description>
1939<t>
1940   The request included a Range request-header field (&header-range;) and none of
1941   the range-specifier values in this field overlap the current extent
1942   of the selected resource. See &status-416;.
1943</t>
1944</section>
1945
1946<section title="417 Expectation Failed" anchor="status.417">
1947  <iref primary="true" item="417 Expectation Failed (status code)" x:for-anchor=""/>
1948  <iref primary="true" item="Status Codes" subitem="417 Expectation Failed" x:for-anchor=""/>
1949<t>
1950   The expectation given in an Expect request-header field (see <xref target="header.expect"/>)
1951   could not be met by this server, or, if the server is a proxy,
1952   the server has unambiguous evidence that the request could not be met
1953   by the next-hop server.
1954</t>
1955</section>
1956</section>
1957
1958<section title="Server Error 5xx" anchor="status.5xx">
1959<t>
1960   Response status codes beginning with the digit "5" indicate cases in
1961   which the server is aware that it has erred or is incapable of
1962   performing the request. Except when responding to a HEAD request, the
1963   server &SHOULD; include a representation containing an explanation of the
1964   error situation, and whether it is a temporary or permanent
1965   condition. User agents &SHOULD; display any included representation to the
1966   user. These response codes are applicable to any request method.
1967</t>
1968
1969<section title="500 Internal Server Error" anchor="status.500">
1970  <iref primary="true" item="500 Internal Server Error (status code)" x:for-anchor=""/>
1971  <iref primary="true" item="Status Codes" subitem="500 Internal Server Error" x:for-anchor=""/>
1972<t>
1973   The server encountered an unexpected condition which prevented it
1974   from fulfilling the request.
1975</t>
1976</section>
1977
1978<section title="501 Not Implemented" anchor="status.501">
1979  <iref primary="true" item="501 Not Implemented (status code)" x:for-anchor=""/>
1980  <iref primary="true" item="Status Codes" subitem="501 Not Implemented" x:for-anchor=""/>
1981<t>
1982   The server does not support the functionality required to fulfill the
1983   request. This is the appropriate response when the server does not
1984   recognize the request method and is not capable of supporting it for
1985   any resource.
1986</t>
1987</section>
1988
1989<section title="502 Bad Gateway" anchor="status.502">
1990  <iref primary="true" item="502 Bad Gateway (status code)" x:for-anchor=""/>
1991  <iref primary="true" item="Status Codes" subitem="502 Bad Gateway" x:for-anchor=""/>
1992<t>
1993   The server, while acting as a gateway or proxy, received an invalid
1994   response from the upstream server it accessed in attempting to
1995   fulfill the request.
1996</t>
1997</section>
1998
1999<section title="503 Service Unavailable" anchor="status.503">
2000  <iref primary="true" item="503 Service Unavailable (status code)" x:for-anchor=""/>
2001  <iref primary="true" item="Status Codes" subitem="503 Service Unavailable" x:for-anchor=""/>
2002<t>
2003   The server is currently unable to handle the request due to a
2004   temporary overloading or maintenance of the server. The implication
2005   is that this is a temporary condition which will be alleviated after
2006   some delay. If known, the length of the delay &MAY; be indicated in a
2007   Retry-After header field. If no Retry-After is given, the client &SHOULD;
2008   handle the response as it would for a 500 response.
2009</t>
2010<x:note>
2011  <t>
2012    <x:h>Note:</x:h> The existence of the 503 status code does not imply that a
2013    server must use it when becoming overloaded. Some servers might wish
2014    to simply refuse the connection.
2015  </t>
2016</x:note>
2017</section>
2018
2019<section title="504 Gateway Timeout" anchor="status.504">
2020  <iref primary="true" item="504 Gateway Timeout (status code)" x:for-anchor=""/>
2021  <iref primary="true" item="Status Codes" subitem="504 Gateway Timeout" x:for-anchor=""/>
2022<t>
2023   The server, while acting as a gateway or proxy, did not receive a
2024   timely response from the upstream server specified by the URI (e.g.,
2025   HTTP, FTP, LDAP) or some other auxiliary server (e.g., DNS) it needed
2026   to access in attempting to complete the request.
2027</t>
2028<x:note>
2029  <t>
2030    <x:h>Note</x:h> to implementors: some deployed proxies are known to
2031    return 400 or 500 when DNS lookups time out.
2032  </t>
2033</x:note>
2034</section>
2035
2036<section title="505 HTTP Version Not Supported" anchor="status.505">
2037  <iref primary="true" item="505 HTTP Version Not Supported (status code)" x:for-anchor=""/>
2038  <iref primary="true" item="Status Codes" subitem="505 HTTP Version Not Supported" x:for-anchor=""/>
2039<t>
2040   The server does not support, or refuses to support, the protocol
2041   version that was used in the request message. The server is
2042   indicating that it is unable or unwilling to complete the request
2043   using the same major version as the client, as described in &http-version;,
2044   other than with this error message. The response &SHOULD; contain
2045   a representation describing why that version is not supported and what other
2046   protocols are supported by that server.
2047</t>
2048
2049</section>
2050</section>
2051</section>
2052
2053
2054<section title="Header Field Definitions" anchor="header.fields">
2055<t>
2056   This section defines the syntax and semantics of HTTP/1.1 header fields
2057   related to request and response semantics.
2058</t>
2059
2060<section title="Allow" anchor="header.allow">
2061  <iref primary="true" item="Allow header" x:for-anchor=""/>
2062  <iref primary="true" item="Headers" subitem="Allow" x:for-anchor=""/>
2063  <x:anchor-alias value="Allow"/>
2064  <x:anchor-alias value="Allow-v"/>
2065<t>
2066   The "Allow" response-header field lists the set of methods advertised as
2067   supported by the target resource. The purpose of
2068   this field is strictly to inform the recipient of valid methods
2069   associated with the resource.
2070</t>
2071<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Allow"/><iref primary="true" item="Grammar" subitem="Allow-v"/>
2072  <x:ref>Allow</x:ref>   = "Allow" ":" <x:ref>OWS</x:ref> <x:ref>Allow-v</x:ref>
2073  <x:ref>Allow-v</x:ref> = #<x:ref>Method</x:ref>
2074</artwork></figure>
2075<t>
2076      Example of use:
2077</t>
2078<figure><artwork type="example">
2079  Allow: GET, HEAD, PUT
2080</artwork></figure>
2081<t>
2082      The actual set of allowed methods is defined
2083      by the origin server at the time of each request.
2084</t>
2085<t>
2086      A proxy &MUST-NOT; modify the Allow header field even if it does not
2087      understand all the methods specified, since the user agent might
2088      have other means of communicating with the origin server.
2089</t>
2090</section>
2091
2092<section title="Expect" anchor="header.expect">
2093  <iref primary="true" item="Expect header" x:for-anchor=""/>
2094  <iref primary="true" item="Headers" subitem="Expect" x:for-anchor=""/>
2095  <x:anchor-alias value="Expect"/>
2096  <x:anchor-alias value="Expect-v"/>
2097  <x:anchor-alias value="expectation"/>
2098  <x:anchor-alias value="expectation-extension"/>
2099  <x:anchor-alias value="expect-params"/>
2100<t>
2101   The "Expect" request-header field is used to indicate that particular
2102   server behaviors are required by the client.
2103</t>
2104<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"/>
2105  <x:ref>Expect</x:ref>       = "Expect" ":" <x:ref>OWS</x:ref> <x:ref>Expect-v</x:ref>
2106  <x:ref>Expect-v</x:ref>     = 1#<x:ref>expectation</x:ref>
2107 
2108  <x:ref>expectation</x:ref>  = "100-continue" / <x:ref>expectation-extension</x:ref>
2109  <x:ref>expectation-extension</x:ref> = <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> )
2110                           *<x:ref>expect-params</x:ref> ]
2111  <x:ref>expect-params</x:ref> = ";" <x:ref>token</x:ref> [ "=" ( <x:ref>token</x:ref> / <x:ref>quoted-string</x:ref> ) ]
2112</artwork></figure>
2113<t>
2114   A server that does not understand or is unable to comply with any of
2115   the expectation values in the Expect field of a request &MUST; respond
2116   with appropriate error status code. The server &MUST; respond with a 417
2117   (Expectation Failed) status code if any of the expectations cannot be met
2118   or, if there are other problems with the request, some other 4xx
2119   status code.
2120</t>
2121<t>
2122   This header field is defined with extensible syntax to allow for
2123   future extensions. If a server receives a request containing an
2124   Expect field that includes an expectation-extension that it does not
2125   support, it &MUST; respond with a 417 (Expectation Failed) status code.
2126</t>
2127<t>
2128   Comparison of expectation values is case-insensitive for unquoted
2129   tokens (including the 100-continue token), and is case-sensitive for
2130   quoted-string expectation-extensions.
2131</t>
2132<t>
2133   The Expect mechanism is hop-by-hop: that is, an HTTP/1.1 proxy &MUST;
2134   return a 417 (Expectation Failed) status code if it receives a request
2135   with an expectation that it cannot meet. However, the Expect
2136   request-header field itself is end-to-end; it &MUST; be forwarded if the
2137   request is forwarded.
2138</t>
2139<t>
2140   Many older HTTP/1.0 and HTTP/1.1 applications do not understand the
2141   Expect header field.
2142</t>
2143<t>
2144   See &use100; for the use of the 100 (Continue) status code.
2145</t>
2146</section>
2147
2148<section title="From" anchor="header.from">
2149  <iref primary="true" item="From header" x:for-anchor=""/>
2150  <iref primary="true" item="Headers" subitem="From" x:for-anchor=""/>
2151  <x:anchor-alias value="From"/>
2152  <x:anchor-alias value="From-v"/>
2153  <x:anchor-alias value="mailbox"/>
2154<t>
2155   The "From" request-header field, if given, &SHOULD; contain an Internet
2156   e-mail address for the human user who controls the requesting user
2157   agent. The address &SHOULD; be machine-usable, as defined by "mailbox"
2158   in <xref x:sec="3.4" x:fmt="of" target="RFC5322"/>:
2159</t>
2160<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="From"/><iref primary="true" item="Grammar" subitem="From-v"/>
2161  <x:ref>From</x:ref>    = "From" ":" <x:ref>OWS</x:ref> <x:ref>From-v</x:ref>
2162  <x:ref>From-v</x:ref>  = <x:ref>mailbox</x:ref>
2163 
2164  <x:ref>mailbox</x:ref> = &lt;mailbox, defined in <xref x:sec="3.4" x:fmt="," target="RFC5322"/>&gt;
2165</artwork></figure>
2166<t>
2167   An example is:
2168</t>
2169<figure><artwork type="example">
2170  From: webmaster@example.org
2171</artwork></figure>
2172<t>
2173   This header field &MAY; be used for logging purposes and as a means for
2174   identifying the source of invalid or unwanted requests. It &SHOULD-NOT; 
2175   be used as an insecure form of access protection. The interpretation
2176   of this field is that the request is being performed on behalf of the
2177   person given, who accepts responsibility for the method performed. In
2178   particular, robot agents &SHOULD; include this header field so that the
2179   person responsible for running the robot can be contacted if problems
2180   occur on the receiving end.
2181</t>
2182<t>
2183   The Internet e-mail address in this field &MAY; be separate from the
2184   Internet host which issued the request. For example, when a request
2185   is passed through a proxy the original issuer's address &SHOULD; be
2186   used.
2187</t>
2188<t>
2189   The client &SHOULD-NOT;  send the From header field without the user's
2190   approval, as it might conflict with the user's privacy interests or
2191   their site's security policy. It is strongly recommended that the
2192   user be able to disable, enable, and modify the value of this field
2193   at any time prior to a request.
2194</t>
2195</section>
2196
2197<section title="Location" anchor="header.location">
2198  <iref primary="true" item="Location header" x:for-anchor=""/>
2199  <iref primary="true" item="Headers" subitem="Location" x:for-anchor=""/>
2200  <x:anchor-alias value="Location"/>
2201  <x:anchor-alias value="Location-v"/>
2202<t>
2203   The "Location" response-header field is used to identify a newly created
2204   resource, or to redirect the recipient to a different location for
2205   completion of the request.
2206</t>
2207<t>
2208   For 201 (Created) responses, the Location is the URI of the new resource
2209   which was created by the request. For 3xx responses, the location &SHOULD;
2210   indicate the server's preferred URI for automatic redirection to the
2211   resource.
2212</t>
2213<t>
2214   The field value consists of a single URI-reference. When it has the form
2215   of a relative reference (<xref target="RFC3986" x:fmt="," x:sec="4.2"/>),
2216   the final value is computed by resolving it against the effective request
2217   URI (<xref target="RFC3986" x:fmt="," x:sec="5"/>).
2218</t>
2219<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Location"/><iref primary="true" item="Grammar" subitem="Location-v"/>
2220  <x:ref>Location</x:ref>       = "Location" ":" <x:ref>OWS</x:ref> <x:ref>Location-v</x:ref>
2221  <x:ref>Location-v</x:ref>     = <x:ref>URI-reference</x:ref>
2222</artwork></figure>
2223<figure>
2224<preamble>Examples are:</preamble><!--DO NOT DARE changing the vertical WSP below, it's necessary this way for xml2rfc-->
2225<artwork type="example">
2226  Location: http://www.example.org/pub/WWW/People.html#tim
2227</artwork></figure><figure><artwork type="example">  Location: /index.html
2228</artwork></figure>
2229<t>
2230   There are circumstances in which a fragment identifier in a Location URI
2231   would not be appropriate:
2232   <list style="symbols">
2233      <t>With a 201 Created response, because in this usage the Location header
2234      field specifies the URI for the entire created resource.</t>
2235      <t>With 305 Use Proxy.</t>
2236   </list>
2237</t>
2238<x:note>
2239  <t>
2240    <x:h>Note:</x:h> This specification does not define precedence rules
2241    for the case where the original URI, as navigated to by the user
2242    agent, and the Location header field value both contain fragment
2243    identifiers.
2244  </t>
2245</x:note>
2246<x:note>
2247  <t>
2248    <x:h>Note:</x:h> The Content-Location header field (&header-content-location;) differs
2249    from Location in that the Content-Location identifies the most specific
2250    resource corresponding to the enclosed representation.
2251    It is therefore possible for a response to contain header fields for
2252    both Location and Content-Location.
2253  </t>
2254</x:note>
2255</section>
2256
2257<section title="Max-Forwards" anchor="header.max-forwards">
2258  <iref primary="true" item="Max-Forwards header" x:for-anchor=""/>
2259  <iref primary="true" item="Headers" subitem="Max-Forwards" x:for-anchor=""/>
2260  <x:anchor-alias value="Max-Forwards"/>
2261  <x:anchor-alias value="Max-Forwards-v"/>
2262<t>
2263   The "Max-Forwards" request-header field provides a mechanism with the
2264   TRACE (<xref target="TRACE"/>) and OPTIONS (<xref target="OPTIONS"/>)
2265   methods to limit the number of times that the request is forwarded by
2266   proxies or gateways. This can be useful when the client is attempting to
2267   trace a request which appears to be failing or looping in mid-chain.
2268</t>
2269<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Max-Forwards"/><iref primary="true" item="Grammar" subitem="Max-Forwards-v"/>
2270  <x:ref>Max-Forwards</x:ref>   = "Max-Forwards" ":" <x:ref>OWS</x:ref> <x:ref>Max-Forwards-v</x:ref>
2271  <x:ref>Max-Forwards-v</x:ref> = 1*<x:ref>DIGIT</x:ref>
2272</artwork></figure>
2273<t>
2274   The Max-Forwards value is a decimal integer indicating the remaining
2275   number of times this request message can be forwarded.
2276</t>
2277<t>
2278   Each proxy or gateway recipient of a TRACE or OPTIONS request
2279   containing a Max-Forwards header field &MUST; check and update its
2280   value prior to forwarding the request. If the received value is zero
2281   (0), the recipient &MUST-NOT; forward the request; instead, it &MUST;
2282   respond as the final recipient. If the received Max-Forwards value is
2283   greater than zero, then the forwarded message &MUST; contain an updated
2284   Max-Forwards field with a value decremented by one (1).
2285</t>
2286<t>
2287   The Max-Forwards header field &MAY; be ignored for all other methods
2288   defined by this specification and for any extension methods for which
2289   it is not explicitly referred to as part of that method definition.
2290</t>
2291</section>
2292
2293<section title="Referer" anchor="header.referer">
2294  <iref primary="true" item="Referer header" x:for-anchor=""/>
2295  <iref primary="true" item="Headers" subitem="Referer" x:for-anchor=""/>
2296  <x:anchor-alias value="Referer"/>
2297  <x:anchor-alias value="Referer-v"/>
2298<t>
2299   The "Referer" [sic] request-header field allows the client to specify the
2300   URI of the resource from which the effective request URI was obtained (the
2301   "referrer", although the header field is misspelled.).
2302</t>
2303<t>
2304   The Referer header field allows servers to generate lists of back-links to
2305   resources for interest, logging, optimized caching, etc. It also allows
2306   obsolete or mistyped links to be traced for maintenance. Some servers use
2307   Referer as a means of controlling where they allow links from (so-called
2308   "deep linking"), but legitimate requests do not always
2309   contain a Referer header field.
2310</t>
2311<t>
2312   If the effective request URI was obtained from a source that does not have its own
2313   URI (e.g., input from the user keyboard), the Referer field &MUST; either be
2314   sent with the value "about:blank", or not be sent at all. Note that this
2315   requirement does not apply to sources with non-HTTP URIs (e.g., FTP).
2316</t>
2317<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Referer"/><iref primary="true" item="Grammar" subitem="Referer-v"/>
2318  <x:ref>Referer</x:ref>        = "Referer" ":" <x:ref>OWS</x:ref> <x:ref>Referer-v</x:ref>
2319  <x:ref>Referer-v</x:ref>      = <x:ref>absolute-URI</x:ref> / <x:ref>partial-URI</x:ref>
2320</artwork></figure>
2321<t>
2322   Example:
2323</t>
2324<figure><artwork type="example">
2325  Referer: http://www.example.org/hypertext/Overview.html
2326</artwork></figure>
2327<t>
2328   If the field value is a relative URI, it &SHOULD; be interpreted
2329   relative to the effective request URI. The URI &MUST-NOT; include a fragment. See
2330   <xref target="encoding.sensitive.information.in.uris"/> for security considerations.
2331</t>
2332</section>
2333
2334<section title="Retry-After" anchor="header.retry-after">
2335  <iref primary="true" item="Retry-After header" x:for-anchor=""/>
2336  <iref primary="true" item="Headers" subitem="Retry-After" x:for-anchor=""/>
2337  <x:anchor-alias value="Retry-After"/>
2338  <x:anchor-alias value="Retry-After-v"/>
2339<t>
2340   The response-header "Retry-After" field can be used with a 503 (Service
2341   Unavailable) response to indicate how long the service is expected to
2342   be unavailable to the requesting client. This field &MAY; also be used
2343   with any 3xx (Redirection) response to indicate the minimum time the
2344   user-agent is asked wait before issuing the redirected request.
2345</t>
2346<t>
2347   The value of this field can be either an HTTP-date or an integer number
2348   of seconds (in decimal) after the time of the response.
2349</t>
2350<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Retry-After"/><iref primary="true" item="Grammar" subitem="Retry-After-v"/>
2351  <x:ref>Retry-After</x:ref>   = "Retry-After" ":" <x:ref>OWS</x:ref> <x:ref>Retry-After-v</x:ref>
2352  <x:ref>Retry-After-v</x:ref> = <x:ref>HTTP-date</x:ref> / <x:ref>delta-seconds</x:ref>
2353</artwork></figure>
2354<t anchor="rule.delta-seconds">
2355  <x:anchor-alias value="delta-seconds"/>
2356   Time spans are non-negative decimal integers, representing time in
2357   seconds.
2358</t>
2359<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="delta-seconds"/>
2360  <x:ref>delta-seconds</x:ref>  = 1*<x:ref>DIGIT</x:ref>
2361</artwork></figure>
2362<t>
2363   Two examples of its use are
2364</t>
2365<figure><artwork type="example">
2366  Retry-After: Fri, 31 Dec 1999 23:59:59 GMT
2367  Retry-After: 120
2368</artwork></figure>
2369<t>
2370   In the latter example, the delay is 2 minutes.
2371</t>
2372</section>
2373
2374<section title="Server" anchor="header.server">
2375  <iref primary="true" item="Server header" x:for-anchor=""/>
2376  <iref primary="true" item="Headers" subitem="Server" x:for-anchor=""/>
2377  <x:anchor-alias value="Server"/>
2378  <x:anchor-alias value="Server-v"/>
2379<t>
2380   The "Server" response-header field contains information about the
2381   software used by the origin server to handle the request.
2382</t>
2383<t>
2384   The field can contain multiple product tokens (&product-tokens;) and
2385   comments (&header-fields;) identifying the server and any significant
2386   subproducts. The product tokens are listed in order of their significance
2387   for identifying the application.
2388</t>
2389<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Server"/><iref primary="true" item="Grammar" subitem="Server-v"/>
2390  <x:ref>Server</x:ref>         = "Server" ":" <x:ref>OWS</x:ref> <x:ref>Server-v</x:ref>
2391  <x:ref>Server-v</x:ref>       = <x:ref>product</x:ref>
2392                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2393</artwork></figure>
2394<t>
2395   Example:
2396</t>
2397<figure><artwork type="example">
2398  Server: CERN/3.0 libwww/2.17
2399</artwork></figure>
2400<t>
2401   If the response is being forwarded through a proxy, the proxy
2402   application &MUST-NOT; modify the Server response-header field. Instead, it
2403   &MUST; include a Via field (as described in &header-via;).
2404</t>
2405<x:note>
2406  <t>
2407    <x:h>Note:</x:h> Revealing the specific software version of the server might
2408    allow the server machine to become more vulnerable to attacks
2409    against software that is known to contain security holes. Server
2410    implementors are encouraged to make this field a configurable
2411    option.
2412  </t>
2413</x:note>
2414</section>
2415
2416<section title="User-Agent" anchor="header.user-agent">
2417  <iref primary="true" item="User-Agent header" x:for-anchor=""/>
2418  <iref primary="true" item="Headers" subitem="User-Agent" x:for-anchor=""/>
2419  <x:anchor-alias value="User-Agent"/>
2420  <x:anchor-alias value="User-Agent-v"/>
2421<t>
2422   The "User-Agent" request-header field contains information about the user
2423   agent originating the request. User agents &SHOULD; include this field with
2424   requests.
2425</t>
2426<t>
2427   Typically, it is used for statistical purposes, the tracing of protocol
2428   violations, and tailoring responses to avoid particular user agent
2429   limitations.
2430</t>
2431<t>
2432   The field can contain multiple product tokens (&product-tokens;)
2433   and comments (&header-fields;) identifying the agent and its
2434   significant subproducts. By convention, the product tokens are listed in
2435   order of their significance for identifying the application.
2436</t>
2437<t>
2438   Because this field is usually sent on every request a user agent makes,
2439   implementations are encouraged not to include needlessly fine-grained
2440   detail, and to limit (or even prohibit) the addition of subproducts by third
2441   parties. Overly long and detailed User-Agent field values make requests
2442   larger and can also be used to identify ("fingerprint") the user against
2443   their wishes.
2444</t>
2445<t>
2446   Likewise, implementations are encouraged not to use the product tokens of
2447   other implementations in order to declare compatibility with them, as this
2448   circumvents the purpose of the field. Finally, they are encouraged not to
2449   use comments to identify products; doing so makes the field value more
2450   difficult to parse.
2451</t>
2452<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="User-Agent"/><iref primary="true" item="Grammar" subitem="User-Agent-v"/>
2453  <x:ref>User-Agent</x:ref>     = "User-Agent" ":" <x:ref>OWS</x:ref> <x:ref>User-Agent-v</x:ref>
2454  <x:ref>User-Agent-v</x:ref>   = <x:ref>product</x:ref>
2455                   *( <x:ref>RWS</x:ref> ( <x:ref>product</x:ref> / <x:ref>comment</x:ref> ) )
2456</artwork></figure>
2457<t>
2458   Example:
2459</t>
2460<figure><artwork type="example">
2461  User-Agent: CERN-LineMode/2.15 libwww/2.17b3
2462</artwork></figure>
2463</section>
2464
2465</section>
2466
2467<section title="IANA Considerations" anchor="IANA.considerations">
2468
2469<section title="Method Registry" anchor="method.registration">
2470<t>
2471  The registration procedure for HTTP Methods is defined by
2472  <xref target="method.registry"/> of this document.
2473</t>
2474<t>
2475   The HTTP Method Registry shall be created at <eref target="http://www.iana.org/assignments/http-methods"/>
2476   and be populated with the registrations below:
2477</t>
2478<?BEGININC p2-semantics.iana-methods ?>
2479<!--AUTOGENERATED FROM extract-method-defs.xslt, do not edit manually-->
2480<texttable align="left" suppress-title="true" anchor="iana.method.registration.table">
2481   <ttcol>Method</ttcol>
2482   <ttcol>Safe</ttcol>
2483   <ttcol>Reference</ttcol>
2484   <c>CONNECT</c>
2485   <c>no</c>
2486   <c>
2487      <xref target="CONNECT"/>
2488   </c>
2489   <c>DELETE</c>
2490   <c>no</c>
2491   <c>
2492      <xref target="DELETE"/>
2493   </c>
2494   <c>GET</c>
2495   <c>yes</c>
2496   <c>
2497      <xref target="GET"/>
2498   </c>
2499   <c>HEAD</c>
2500   <c>yes</c>
2501   <c>
2502      <xref target="HEAD"/>
2503   </c>
2504   <c>OPTIONS</c>
2505   <c>yes</c>
2506   <c>
2507      <xref target="OPTIONS"/>
2508   </c>
2509   <c>POST</c>
2510   <c>no</c>
2511   <c>
2512      <xref target="POST"/>
2513   </c>
2514   <c>PUT</c>
2515   <c>no</c>
2516   <c>
2517      <xref target="PUT"/>
2518   </c>
2519   <c>TRACE</c>
2520   <c>yes</c>
2521   <c>
2522      <xref target="TRACE"/>
2523   </c>
2524</texttable>
2525<!--(END)-->
2526<?ENDINC p2-semantics.iana-methods ?>
2527</section>
2528
2529<section title="Status Code Registry" anchor="status.code.registration">
2530<t>
2531   The registration procedure for HTTP Status Codes -- previously defined
2532   in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/> -- is now defined
2533   by <xref target="status.code.registry"/> of this document.
2534</t>
2535<t>
2536   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
2537   shall be updated with the registrations below:
2538</t>
2539<?BEGININC p2-semantics.iana-status-codes ?>
2540<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
2541<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
2542   <ttcol>Value</ttcol>
2543   <ttcol>Description</ttcol>
2544   <ttcol>Reference</ttcol>
2545   <c>100</c>
2546   <c>Continue</c>
2547   <c>
2548      <xref target="status.100"/>
2549   </c>
2550   <c>101</c>
2551   <c>Switching Protocols</c>
2552   <c>
2553      <xref target="status.101"/>
2554   </c>
2555   <c>200</c>
2556   <c>OK</c>
2557   <c>
2558      <xref target="status.200"/>
2559   </c>
2560   <c>201</c>
2561   <c>Created</c>
2562   <c>
2563      <xref target="status.201"/>
2564   </c>
2565   <c>202</c>
2566   <c>Accepted</c>
2567   <c>
2568      <xref target="status.202"/>
2569   </c>
2570   <c>203</c>
2571   <c>Non-Authoritative Information</c>
2572   <c>
2573      <xref target="status.203"/>
2574   </c>
2575   <c>204</c>
2576   <c>No Content</c>
2577   <c>
2578      <xref target="status.204"/>
2579   </c>
2580   <c>205</c>
2581   <c>Reset Content</c>
2582   <c>
2583      <xref target="status.205"/>
2584   </c>
2585   <c>300</c>
2586   <c>Multiple Choices</c>
2587   <c>
2588      <xref target="status.300"/>
2589   </c>
2590   <c>301</c>
2591   <c>Moved Permanently</c>
2592   <c>
2593      <xref target="status.301"/>
2594   </c>
2595   <c>302</c>
2596   <c>Found</c>
2597   <c>
2598      <xref target="status.302"/>
2599   </c>
2600   <c>303</c>
2601   <c>See Other</c>
2602   <c>
2603      <xref target="status.303"/>
2604   </c>
2605   <c>305</c>
2606   <c>Use Proxy</c>
2607   <c>
2608      <xref target="status.305"/>
2609   </c>
2610   <c>306</c>
2611   <c>(Unused)</c>
2612   <c>
2613      <xref target="status.306"/>
2614   </c>
2615   <c>307</c>
2616   <c>Temporary Redirect</c>
2617   <c>
2618      <xref target="status.307"/>
2619   </c>
2620   <c>400</c>
2621   <c>Bad Request</c>
2622   <c>
2623      <xref target="status.400"/>
2624   </c>
2625   <c>402</c>
2626   <c>Payment Required</c>
2627   <c>
2628      <xref target="status.402"/>
2629   </c>
2630   <c>403</c>
2631   <c>Forbidden</c>
2632   <c>
2633      <xref target="status.403"/>
2634   </c>
2635   <c>404</c>
2636   <c>Not Found</c>
2637   <c>
2638      <xref target="status.404"/>
2639   </c>
2640   <c>405</c>
2641   <c>Method Not Allowed</c>
2642   <c>
2643      <xref target="status.405"/>
2644   </c>
2645   <c>406</c>
2646   <c>Not Acceptable</c>
2647   <c>
2648      <xref target="status.406"/>
2649   </c>
2650   <c>407</c>
2651   <c>Proxy Authentication Required</c>
2652   <c>
2653      <xref target="status.407"/>
2654   </c>
2655   <c>408</c>
2656   <c>Request Timeout</c>
2657   <c>
2658      <xref target="status.408"/>
2659   </c>
2660   <c>409</c>
2661   <c>Conflict</c>
2662   <c>
2663      <xref target="status.409"/>
2664   </c>
2665   <c>410</c>
2666   <c>Gone</c>
2667   <c>
2668      <xref target="status.410"/>
2669   </c>
2670   <c>411</c>
2671   <c>Length Required</c>
2672   <c>
2673      <xref target="status.411"/>
2674   </c>
2675   <c>413</c>
2676   <c>Request Entity Too Large</c>
2677   <c>
2678      <xref target="status.413"/>
2679   </c>
2680   <c>414</c>
2681   <c>URI Too Long</c>
2682   <c>
2683      <xref target="status.414"/>
2684   </c>
2685   <c>415</c>
2686   <c>Unsupported Media Type</c>
2687   <c>
2688      <xref target="status.415"/>
2689   </c>
2690   <c>417</c>
2691   <c>Expectation Failed</c>
2692   <c>
2693      <xref target="status.417"/>
2694   </c>
2695   <c>500</c>
2696   <c>Internal Server Error</c>
2697   <c>
2698      <xref target="status.500"/>
2699   </c>
2700   <c>501</c>
2701   <c>Not Implemented</c>
2702   <c>
2703      <xref target="status.501"/>
2704   </c>
2705   <c>502</c>
2706   <c>Bad Gateway</c>
2707   <c>
2708      <xref target="status.502"/>
2709   </c>
2710   <c>503</c>
2711   <c>Service Unavailable</c>
2712   <c>
2713      <xref target="status.503"/>
2714   </c>
2715   <c>504</c>
2716   <c>Gateway Timeout</c>
2717   <c>
2718      <xref target="status.504"/>
2719   </c>
2720   <c>505</c>
2721   <c>HTTP Version Not Supported</c>
2722   <c>
2723      <xref target="status.505"/>
2724   </c>
2725</texttable>
2726<!--(END)-->
2727<?ENDINC p2-semantics.iana-status-codes ?>
2728</section>
2729<section title="Header Field Registration" anchor="header.field.registration">
2730<t>
2731   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> shall be updated
2732   with the permanent registrations below (see <xref target="RFC3864"/>):
2733</t>
2734<?BEGININC p2-semantics.iana-headers ?>
2735<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
2736<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
2737   <ttcol>Header Field Name</ttcol>
2738   <ttcol>Protocol</ttcol>
2739   <ttcol>Status</ttcol>
2740   <ttcol>Reference</ttcol>
2741
2742   <c>Allow</c>
2743   <c>http</c>
2744   <c>standard</c>
2745   <c>
2746      <xref target="header.allow"/>
2747   </c>
2748   <c>Expect</c>
2749   <c>http</c>
2750   <c>standard</c>
2751   <c>
2752      <xref target="header.expect"/>
2753   </c>
2754   <c>From</c>
2755   <c>http</c>
2756   <c>standard</c>
2757   <c>
2758      <xref target="header.from"/>
2759   </c>
2760   <c>Location</c>
2761   <c>http</c>
2762   <c>standard</c>
2763   <c>
2764      <xref target="header.location"/>
2765   </c>
2766   <c>Max-Forwards</c>
2767   <c>http</c>
2768   <c>standard</c>
2769   <c>
2770      <xref target="header.max-forwards"/>
2771   </c>
2772   <c>Referer</c>
2773   <c>http</c>
2774   <c>standard</c>
2775   <c>
2776      <xref target="header.referer"/>
2777   </c>
2778   <c>Retry-After</c>
2779   <c>http</c>
2780   <c>standard</c>
2781   <c>
2782      <xref target="header.retry-after"/>
2783   </c>
2784   <c>Server</c>
2785   <c>http</c>
2786   <c>standard</c>
2787   <c>
2788      <xref target="header.server"/>
2789   </c>
2790   <c>User-Agent</c>
2791   <c>http</c>
2792   <c>standard</c>
2793   <c>
2794      <xref target="header.user-agent"/>
2795   </c>
2796</texttable>
2797<!--(END)-->
2798<?ENDINC p2-semantics.iana-headers ?>
2799<t>
2800   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
2801</t>
2802</section>
2803</section>
2804
2805<section title="Security Considerations" anchor="security.considerations">
2806<t>
2807   This section is meant to inform application developers, information
2808   providers, and users of the security limitations in HTTP/1.1 as
2809   described by this document. The discussion does not include
2810   definitive solutions to the problems revealed, though it does make
2811   some suggestions for reducing security risks.
2812</t>
2813
2814<section title="Transfer of Sensitive Information" anchor="security.sensitive">
2815<t>
2816   Like any generic data transfer protocol, HTTP cannot regulate the
2817   content of the data that is transferred, nor is there any a priori
2818   method of determining the sensitivity of any particular piece of
2819   information within the context of any given request. Therefore,
2820   applications &SHOULD; supply as much control over this information as
2821   possible to the provider of that information. Four header fields are
2822   worth special mention in this context: Server, Via, Referer and From.
2823</t>
2824<t>
2825   Revealing the specific software version of the server might allow the
2826   server machine to become more vulnerable to attacks against software
2827   that is known to contain security holes. Implementors &SHOULD; make the
2828   Server header field a configurable option.
2829</t>
2830<t>
2831   Proxies which serve as a portal through a network firewall &SHOULD;
2832   take special precautions regarding the transfer of header information
2833   that identifies the hosts behind the firewall. In particular, they
2834   &SHOULD; remove, or replace with sanitized versions, any Via fields
2835   generated behind the firewall.
2836</t>
2837<t>
2838   The Referer header field allows reading patterns to be studied and reverse
2839   links drawn. Although it can be very useful, its power can be abused
2840   if user details are not separated from the information contained in
2841   the Referer. Even when the personal information has been removed, the
2842   Referer header field might indicate a private document's URI whose
2843   publication would be inappropriate.
2844</t>
2845<t>
2846   The information sent in the From field might conflict with the user's
2847   privacy interests or their site's security policy, and hence it
2848   &SHOULD-NOT;  be transmitted without the user being able to disable,
2849   enable, and modify the contents of the field. The user &MUST; be able
2850   to set the contents of this field within a user preference or
2851   application defaults configuration.
2852</t>
2853<t>
2854   We suggest, though do not require, that a convenient toggle interface
2855   be provided for the user to enable or disable the sending of From and
2856   Referer information.
2857</t>
2858<t>
2859   The User-Agent (<xref target="header.user-agent"/>) or Server (<xref
2860   target="header.server"/>) header fields can sometimes be used to determine
2861   that a specific client or server have a particular security hole which might
2862   be exploited. Unfortunately, this same information is often used for other
2863   valuable purposes for which HTTP currently has no better mechanism.
2864</t>
2865<t>
2866   Furthermore, the User-Agent header field may contain enough entropy to be
2867   used, possibly in conjunction with other material, to uniquely identify the
2868   user.
2869</t>
2870<t>
2871   Some methods, like TRACE (<xref target="TRACE"/>), expose information
2872   that was sent in request header fields within the body of their response.
2873   Clients &SHOULD; be careful with sensitive information, like Cookies,
2874   Authorization credentials and other header fields that might be used to
2875   collect data from the client.
2876</t> 
2877</section>
2878
2879<section title="Encoding Sensitive Information in URIs" anchor="encoding.sensitive.information.in.uris">
2880<t>
2881   Because the source of a link might be private information or might
2882   reveal an otherwise private information source, it is strongly
2883   recommended that the user be able to select whether or not the
2884   Referer field is sent. For example, a browser client could have a
2885   toggle switch for browsing openly/anonymously, which would
2886   respectively enable/disable the sending of Referer and From
2887   information.
2888</t>
2889<t>
2890   Clients &SHOULD-NOT; include a Referer header field in a (non-secure)
2891   HTTP request if the referring page was transferred with a secure
2892   protocol.
2893</t>
2894<t>
2895   Authors of services &SHOULD-NOT; use GET-based forms for the submission of
2896   sensitive data because that data will be placed in the request-target. Many
2897   existing servers, proxies, and user agents log or display the request-target
2898   in places where it might be visible to third parties. Such services can
2899   use POST-based form submission instead.
2900</t>
2901</section>
2902
2903<section title="Location Headers and Spoofing" anchor="location.spoofing">
2904<t>
2905   If a single server supports multiple organizations that do not trust
2906   one another, then it &MUST; check the values of Location and Content-Location
2907   header fields in responses that are generated under control of
2908   said organizations to make sure that they do not attempt to
2909   invalidate resources over which they have no authority.
2910</t>
2911</section>
2912
2913<section title="Security Considerations for CONNECT">
2914<t>
2915   Since tunneled data is opaque to the proxy, there are additional
2916   risks to tunneling to other well-known or reserved ports.
2917   A HTTP client CONNECTing to port 25 could relay spam
2918   via SMTP, for example. As such, proxies &SHOULD; restrict CONNECT
2919   access to a small number of known ports.
2920</t>
2921</section>
2922
2923</section>
2924
2925<section title="Acknowledgments" anchor="ack">
2926</section>
2927</middle>
2928<back>
2929
2930<references title="Normative References">
2931
2932<reference anchor="Part1">
2933  <front>
2934    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
2935    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2936      <organization abbrev="Day Software">Day Software</organization>
2937      <address><email>fielding@gbiv.com</email></address>
2938    </author>
2939    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2940      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2941      <address><email>jg@freedesktop.org</email></address>
2942    </author>
2943    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2944      <organization abbrev="HP">Hewlett-Packard Company</organization>
2945      <address><email>JeffMogul@acm.org</email></address>
2946    </author>
2947    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2948      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2949      <address><email>henrikn@microsoft.com</email></address>
2950    </author>
2951    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2952      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2953      <address><email>LMM@acm.org</email></address>
2954    </author>
2955    <author initials="P." surname="Leach" fullname="Paul J. Leach">
2956      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2957      <address><email>paulle@microsoft.com</email></address>
2958    </author>
2959    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
2960      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
2961      <address><email>timbl@w3.org</email></address>
2962    </author>
2963    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
2964      <organization abbrev="W3C">World Wide Web Consortium</organization>
2965      <address><email>ylafon@w3.org</email></address>
2966    </author>
2967    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
2968      <organization abbrev="greenbytes">greenbytes GmbH</organization>
2969      <address><email>julian.reschke@greenbytes.de</email></address>
2970    </author>
2971    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
2972  </front>
2973  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
2974  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
2975</reference>
2976
2977<reference anchor="Part3">
2978  <front>
2979    <title abbrev="HTTP/1.1">HTTP/1.1, part 3: Message Payload and Content Negotiation</title>
2980    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
2981      <organization abbrev="Day Software">Day Software</organization>
2982      <address><email>fielding@gbiv.com</email></address>
2983    </author>
2984    <author initials="J." surname="Gettys" fullname="Jim Gettys">
2985      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
2986      <address><email>jg@freedesktop.org</email></address>
2987    </author>
2988    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
2989      <organization abbrev="HP">Hewlett-Packard Company</organization>
2990      <address><email>JeffMogul@acm.org</email></address>
2991    </author>
2992    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
2993      <organization abbrev="Microsoft">Microsoft Corporation</organization>
2994      <address><email>henrikn@microsoft.com</email></address>
2995    </author>
2996    <author initials="L." surname="Masinter" fullname="Larry Masinter">
2997      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
2998      <address><email>LMM@acm.org</email></address>
2999    </author>
3000    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3001      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3002      <address><email>paulle@microsoft.com</email></address>
3003    </author>
3004    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3005      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3006      <address><email>timbl@w3.org</email></address>
3007    </author>
3008    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3009      <organization abbrev="W3C">World Wide Web Consortium</organization>
3010      <address><email>ylafon@w3.org</email></address>
3011    </author>
3012    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3013      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3014      <address><email>julian.reschke@greenbytes.de</email></address>
3015    </author>
3016    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3017  </front>
3018  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p3-payload-&ID-VERSION;"/>
3019  <x:source href="p3-payload.xml" basename="p3-payload"/>
3020</reference>
3021
3022<reference anchor="Part4">
3023  <front>
3024    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
3025    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3026      <organization abbrev="Day Software">Day Software</organization>
3027      <address><email>fielding@gbiv.com</email></address>
3028    </author>
3029    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3030      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3031      <address><email>jg@freedesktop.org</email></address>
3032    </author>
3033    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3034      <organization abbrev="HP">Hewlett-Packard Company</organization>
3035      <address><email>JeffMogul@acm.org</email></address>
3036    </author>
3037    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3038      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3039      <address><email>henrikn@microsoft.com</email></address>
3040    </author>
3041    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3042      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3043      <address><email>LMM@acm.org</email></address>
3044    </author>
3045    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3046      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3047      <address><email>paulle@microsoft.com</email></address>
3048    </author>
3049    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3050      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3051      <address><email>timbl@w3.org</email></address>
3052    </author>
3053    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3054      <organization abbrev="W3C">World Wide Web Consortium</organization>
3055      <address><email>ylafon@w3.org</email></address>
3056    </author>
3057    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3058      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3059      <address><email>julian.reschke@greenbytes.de</email></address>
3060    </author>
3061    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3062  </front>
3063  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
3064  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
3065</reference>
3066
3067<reference anchor="Part5">
3068  <front>
3069    <title abbrev="HTTP/1.1">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
3070    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3071      <organization abbrev="Day Software">Day Software</organization>
3072      <address><email>fielding@gbiv.com</email></address>
3073    </author>
3074    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3075      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3076      <address><email>jg@freedesktop.org</email></address>
3077    </author>
3078    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3079      <organization abbrev="HP">Hewlett-Packard Company</organization>
3080      <address><email>JeffMogul@acm.org</email></address>
3081    </author>
3082    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3083      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3084      <address><email>henrikn@microsoft.com</email></address>
3085    </author>
3086    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3087      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3088      <address><email>LMM@acm.org</email></address>
3089    </author>
3090    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3091      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3092      <address><email>paulle@microsoft.com</email></address>
3093    </author>
3094    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3095      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3096      <address><email>timbl@w3.org</email></address>
3097    </author>
3098    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3099      <organization abbrev="W3C">World Wide Web Consortium</organization>
3100      <address><email>ylafon@w3.org</email></address>
3101    </author>
3102    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3103      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3104      <address><email>julian.reschke@greenbytes.de</email></address>
3105    </author>
3106    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3107  </front>
3108  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p5-range-&ID-VERSION;"/>
3109  <x:source href="p5-range.xml" basename="p5-range"/>
3110</reference>
3111
3112<reference anchor="Part6">
3113  <front>
3114    <title abbrev="HTTP/1.1">HTTP/1.1, part 6: Caching</title>
3115    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3116      <organization abbrev="Day Software">Day Software</organization>
3117      <address><email>fielding@gbiv.com</email></address>
3118    </author>
3119    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3120      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3121      <address><email>jg@freedesktop.org</email></address>
3122    </author>
3123    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3124      <organization abbrev="HP">Hewlett-Packard Company</organization>
3125      <address><email>JeffMogul@acm.org</email></address>
3126    </author>
3127    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3128      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3129      <address><email>henrikn@microsoft.com</email></address>
3130    </author>
3131    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3132      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3133      <address><email>LMM@acm.org</email></address>
3134    </author>
3135    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3136      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3137      <address><email>paulle@microsoft.com</email></address>
3138    </author>
3139    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3140      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3141      <address><email>timbl@w3.org</email></address>
3142    </author>
3143    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3144      <organization abbrev="W3C">World Wide Web Consortium</organization>
3145      <address><email>ylafon@w3.org</email></address>
3146    </author>
3147    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
3148      <address><email>mnot@mnot.net</email></address>
3149    </author>
3150    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3151      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3152      <address><email>julian.reschke@greenbytes.de</email></address>
3153    </author>
3154    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3155  </front>
3156  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
3157  <x:source href="p6-cache.xml" basename="p6-cache"/>
3158</reference>
3159
3160<reference anchor="Part7">
3161  <front>
3162    <title abbrev="HTTP/1.1">HTTP/1.1, part 7: Authentication</title>
3163    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
3164      <organization abbrev="Day Software">Day Software</organization>
3165      <address><email>fielding@gbiv.com</email></address>
3166    </author>
3167    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3168      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
3169      <address><email>jg@freedesktop.org</email></address>
3170    </author>
3171    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3172      <organization abbrev="HP">Hewlett-Packard Company</organization>
3173      <address><email>JeffMogul@acm.org</email></address>
3174    </author>
3175    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
3176      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3177      <address><email>henrikn@microsoft.com</email></address>
3178    </author>
3179    <author initials="L." surname="Masinter" fullname="Larry Masinter">
3180      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
3181      <address><email>LMM@acm.org</email></address>
3182    </author>
3183    <author initials="P." surname="Leach" fullname="Paul J. Leach">
3184      <organization abbrev="Microsoft">Microsoft Corporation</organization>
3185      <address><email>paulle@microsoft.com</email></address>
3186    </author>
3187    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3188      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3189      <address><email>timbl@w3.org</email></address>
3190    </author>
3191    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
3192      <organization abbrev="W3C">World Wide Web Consortium</organization>
3193      <address><email>ylafon@w3.org</email></address>
3194    </author>
3195    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
3196      <organization abbrev="greenbytes">greenbytes GmbH</organization>
3197      <address><email>julian.reschke@greenbytes.de</email></address>
3198    </author>
3199    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
3200  </front>
3201  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p7-auth-&ID-VERSION;"/>
3202  <x:source href="p7-auth.xml" basename="p7-auth"/>
3203</reference>
3204
3205<reference anchor="RFC2119">
3206  <front>
3207    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
3208    <author initials="S." surname="Bradner" fullname="Scott Bradner">
3209      <organization>Harvard University</organization>
3210      <address><email>sob@harvard.edu</email></address>
3211    </author>
3212    <date month="March" year="1997"/>
3213  </front>
3214  <seriesInfo name="BCP" value="14"/>
3215  <seriesInfo name="RFC" value="2119"/>
3216</reference>
3217
3218<reference anchor="RFC3986">
3219 <front>
3220  <title abbrev='URI Generic Syntax'>Uniform Resource Identifier (URI): Generic Syntax</title>
3221  <author initials='T.' surname='Berners-Lee' fullname='Tim Berners-Lee'>
3222    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
3223    <address>
3224       <email>timbl@w3.org</email>
3225       <uri>http://www.w3.org/People/Berners-Lee/</uri>
3226    </address>
3227  </author>
3228  <author initials='R.' surname='Fielding' fullname='Roy T. Fielding'>
3229    <organization abbrev="Day Software">Day Software</organization>
3230    <address>
3231      <email>fielding@gbiv.com</email>
3232      <uri>http://roy.gbiv.com/</uri>
3233    </address>
3234  </author>
3235  <author initials='L.' surname='Masinter' fullname='Larry Masinter'>
3236    <organization abbrev="Adobe Systems">Adobe Systems Incorporated</organization>
3237    <address>
3238      <email>LMM@acm.org</email>
3239      <uri>http://larry.masinter.net/</uri>
3240    </address>
3241  </author>
3242  <date month='January' year='2005'></date>
3243 </front>
3244 <seriesInfo name="STD" value="66"/>
3245 <seriesInfo name="RFC" value="3986"/>
3246</reference>
3247
3248<reference anchor="RFC5234">
3249  <front>
3250    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
3251    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
3252      <organization>Brandenburg InternetWorking</organization>
3253      <address>
3254        <email>dcrocker@bbiw.net</email>
3255      </address> 
3256    </author>
3257    <author initials="P." surname="Overell" fullname="Paul Overell">
3258      <organization>THUS plc.</organization>
3259      <address>
3260        <email>paul.overell@thus.net</email>
3261      </address>
3262    </author>
3263    <date month="January" year="2008"/>
3264  </front>
3265  <seriesInfo name="STD" value="68"/>
3266  <seriesInfo name="RFC" value="5234"/>
3267</reference>
3268
3269</references>
3270
3271<references title="Informative References">
3272
3273<reference anchor="RFC1945">
3274  <front>
3275    <title abbrev="HTTP/1.0">Hypertext Transfer Protocol -- HTTP/1.0</title>
3276    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3277      <organization>MIT, Laboratory for Computer Science</organization>
3278      <address><email>timbl@w3.org</email></address>
3279    </author>
3280    <author initials="R.T." surname="Fielding" fullname="Roy T. Fielding">
3281      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3282      <address><email>fielding@ics.uci.edu</email></address>
3283    </author>
3284    <author initials="H.F." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3285      <organization>W3 Consortium, MIT Laboratory for Computer Science</organization>
3286      <address><email>frystyk@w3.org</email></address>
3287    </author>
3288    <date month="May" year="1996"/>
3289  </front>
3290  <seriesInfo name="RFC" value="1945"/>
3291</reference>
3292
3293<reference anchor="RFC2068">
3294  <front>
3295    <title abbrev="HTTP/1.1">Hypertext Transfer Protocol -- HTTP/1.1</title>
3296    <author initials="R." surname="Fielding" fullname="Roy T. Fielding">
3297      <organization>University of California, Irvine, Department of Information and Computer Science</organization>
3298      <address><email>fielding@ics.uci.edu</email></address>
3299    </author>
3300    <author initials="J." surname="Gettys" fullname="Jim Gettys">
3301      <organization>MIT Laboratory for Computer Science</organization>
3302      <address><email>jg@w3.org</email></address>
3303    </author>
3304    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
3305      <organization>Digital Equipment Corporation, Western Research Laboratory</organization>
3306      <address><email>mogul@wrl.dec.com</email></address>
3307    </author>
3308    <author initials="H." surname="Nielsen" fullname="Henrik Frystyk Nielsen">
3309      <organization>MIT Laboratory for Computer Science</organization>
3310      <address><email>frystyk@w3.org</email></address>
3311    </author>
3312    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
3313      <organization>MIT Laboratory for Computer Science</organization>
3314      <address><email>timbl@w3.org</email></address>
3315    </author>
3316    <date month="January" year="1997"/>
3317  </front>
3318  <seriesInfo name="RFC" value="2068"/>
3319</reference>
3320
3321<reference anchor="RFC2616">
3322  <front>
3323    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
3324    <author initials="R." surname="Fielding" fullname="R. Fielding">
3325      <organization>University of California, Irvine</organization>
3326      <address><email>fielding@ics.uci.edu</email></address>
3327    </author>
3328    <author initials="J." surname="Gettys" fullname="J. Gettys">
3329      <organization>W3C</organization>
3330      <address><email>jg@w3.org</email></address>
3331    </author>
3332    <author initials="J." surname="Mogul" fullname="J. Mogul">
3333      <organization>Compaq Computer Corporation</organization>
3334      <address><email>mogul@wrl.dec.com</email></address>
3335    </author>
3336    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
3337      <organization>MIT Laboratory for Computer Science</organization>
3338      <address><email>frystyk@w3.org</email></address>
3339    </author>
3340    <author initials="L." surname="Masinter" fullname="L. Masinter">
3341      <organization>Xerox Corporation</organization>
3342      <address><email>masinter@parc.xerox.com</email></address>
3343    </author>
3344    <author initials="P." surname="Leach" fullname="P. Leach">
3345      <organization>Microsoft Corporation</organization>
3346      <address><email>paulle@microsoft.com</email></address>
3347    </author>
3348    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
3349      <organization>W3C</organization>
3350      <address><email>timbl@w3.org</email></address>
3351    </author>
3352    <date month="June" year="1999"/>
3353  </front>
3354  <seriesInfo name="RFC" value="2616"/>
3355</reference>
3356
3357<reference anchor='RFC2817'>
3358  <front>
3359    <title>Upgrading to TLS Within HTTP/1.1</title>
3360    <author initials='R.' surname='Khare' fullname='R. Khare'>
3361      <organization>4K Associates / UC Irvine</organization>
3362      <address><email>rohit@4K-associates.com</email></address>
3363    </author>
3364    <author initials='S.' surname='Lawrence' fullname='S. Lawrence'>
3365      <organization>Agranat Systems, Inc.</organization>
3366      <address><email>lawrence@agranat.com</email></address>
3367    </author>
3368    <date year='2000' month='May' />
3369  </front>
3370  <seriesInfo name='RFC' value='2817' />
3371</reference>
3372
3373<reference anchor='RFC3864'>
3374  <front>
3375    <title>Registration Procedures for Message Header Fields</title>
3376    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
3377      <organization>Nine by Nine</organization>
3378      <address><email>GK-IETF@ninebynine.org</email></address>
3379    </author>
3380    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
3381      <organization>BEA Systems</organization>
3382      <address><email>mnot@pobox.com</email></address>
3383    </author>
3384    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
3385      <organization>HP Labs</organization>
3386      <address><email>JeffMogul@acm.org</email></address>
3387    </author>
3388    <date year='2004' month='September' />
3389  </front>
3390  <seriesInfo name='BCP' value='90' />
3391  <seriesInfo name='RFC' value='3864' />
3392</reference>
3393
3394<reference anchor='RFC5226'>
3395  <front>
3396    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
3397    <author initials='T.' surname='Narten' fullname='T. Narten'>
3398      <organization>IBM</organization>
3399      <address><email>narten@us.ibm.com</email></address>
3400    </author>
3401    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
3402      <organization>Google</organization>
3403      <address><email>Harald@Alvestrand.no</email></address>
3404    </author>
3405    <date year='2008' month='May' />
3406  </front>
3407  <seriesInfo name='BCP' value='26' />
3408  <seriesInfo name='RFC' value='5226' />
3409</reference>
3410
3411<reference anchor="RFC5322">
3412  <front>
3413    <title>Internet Message Format</title>
3414    <author initials="P." surname="Resnick" fullname="P. Resnick">
3415      <organization>Qualcomm Incorporated</organization>
3416    </author>
3417    <date year="2008" month="October"/>
3418  </front> 
3419  <seriesInfo name="RFC" value="5322"/>
3420</reference>
3421
3422</references>
3423
3424<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
3425<t>
3426  This document takes over the Status Code Registry, previously defined
3427  in <xref target="RFC2817" x:fmt="of" x:sec="7.1"/>.
3428  (<xref target="status.code.registry"/>)
3429</t>
3430<t>
3431  Clarify definition of POST.
3432  (<xref target="POST"/>)
3433</t>
3434<t>
3435  Failed to consider that there are
3436  many other request methods that are safe to automatically redirect,
3437  and further that the user agent is able to make that determination
3438  based on the request method semantics.
3439  (Sections <xref format="counter" target="status.301"/>,
3440  <xref format="counter" target="status.302"/> and
3441  <xref format="counter" target="status.307"/>)
3442</t>
3443<t>
3444  Deprecate 305 Use Proxy status code, because user agents did not implement it.
3445  It used to indicate that the target resource must be accessed through the
3446  proxy given by the Location field. The Location field gave the URI of the
3447  proxy. The recipient was expected to repeat this single request via the proxy.
3448  (<xref target="status.305"/>)
3449</t>
3450<t>
3451  Reclassify "Allow" as response header field, removing the option to
3452  specify it in a PUT request.
3453  Relax the server requirement on the contents of the Allow header field and
3454  remove requirement on clients to always trust the header field value.
3455  (<xref target="header.allow"/>)
3456</t>
3457<t>
3458  Correct syntax of Location header field to allow URI references (including
3459  relative references and fragments), as referred symbol "absoluteURI" wasn't
3460  what was expected, and add some clarifications as to when use of fragments
3461  would not be appropriate.
3462  (<xref target="header.location"/>)
3463</t>
3464<t>
3465  Allow Referer field value of "about:blank" as alternative to not specifying it.
3466  (<xref target="header.referer"/>)
3467</t>
3468<t>
3469  In the description of the Server header field, the Via field
3470  was described as a SHOULD. The requirement was and is stated
3471  correctly in the description of the Via header field in &header-via;.
3472  (<xref target="header.server"/>)
3473</t>
3474</section>
3475
3476<?BEGININC p2-semantics.abnf-appendix ?>
3477<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
3478<figure>
3479<artwork type="abnf" name="p2-semantics.parsed-abnf">
3480<x:ref>Accept</x:ref> = &lt;Accept, defined in [Part3], Section 6.1&gt;
3481<x:ref>Accept-Charset</x:ref> = &lt;Accept-Charset, defined in [Part3], Section 6.2&gt;
3482<x:ref>Accept-Encoding</x:ref> = &lt;Accept-Encoding, defined in [Part3], Section 6.3&gt;
3483<x:ref>Accept-Language</x:ref> = &lt;Accept-Language, defined in [Part3], Section 6.4&gt;
3484<x:ref>Accept-Ranges</x:ref> = &lt;Accept-Ranges, defined in [Part5], Section 5.1&gt;
3485<x:ref>Age</x:ref> = &lt;Age, defined in [Part6], Section 3.1&gt;
3486<x:ref>Allow</x:ref> = "Allow:" OWS Allow-v
3487<x:ref>Allow-v</x:ref> = [ ( "," / Method ) *( OWS "," [ OWS Method ] ) ]
3488<x:ref>Authorization</x:ref> = &lt;Authorization, defined in [Part7], Section 4.1&gt;
3489
3490<x:ref>ETag</x:ref> = &lt;ETag, defined in [Part4], Section 6.1&gt;
3491<x:ref>Expect</x:ref> = "Expect:" OWS Expect-v
3492<x:ref>Expect-v</x:ref> = *( "," OWS ) expectation *( OWS "," [ OWS expectation ] )
3493
3494<x:ref>From</x:ref> = "From:" OWS From-v
3495<x:ref>From-v</x:ref> = mailbox
3496
3497<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part1], Section 6.1&gt;
3498<x:ref>Host</x:ref> = &lt;Host, defined in [Part1], Section 2.6&gt;
3499
3500<x:ref>If-Match</x:ref> = &lt;If-Match, defined in [Part4], Section 6.2&gt;
3501If-Modified-Since =
3502 &lt;If-Modified-Since, defined in [Part4], Section 6.3&gt;
3503<x:ref>If-None-Match</x:ref> = &lt;If-None-Match, defined in [Part4], Section 6.4&gt;
3504<x:ref>If-Range</x:ref> = &lt;If-Range, defined in [Part5], Section 5.3&gt;
3505If-Unmodified-Since =
3506 &lt;If-Unmodified-Since, defined in [Part4], Section 6.5&gt;
3507
3508<x:ref>Location</x:ref> = "Location:" OWS Location-v
3509<x:ref>Location-v</x:ref> = URI-reference
3510
3511<x:ref>Max-Forwards</x:ref> = "Max-Forwards:" OWS Max-Forwards-v
3512<x:ref>Max-Forwards-v</x:ref> = 1*DIGIT
3513<x:ref>Method</x:ref> = %x4F.50.54.49.4F.4E.53 ; OPTIONS
3514 / %x47.45.54 ; GET
3515 / %x48.45.41.44 ; HEAD
3516 / %x50.4F.53.54 ; POST
3517 / %x50.55.54 ; PUT
3518 / %x44.45.4C.45.54.45 ; DELETE
3519 / %x54.52.41.43.45 ; TRACE
3520 / %x43.4F.4E.4E.45.43.54 ; CONNECT
3521 / extension-method
3522
3523<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
3524
3525Proxy-Authenticate =
3526 &lt;Proxy-Authenticate, defined in [Part7], Section 4.2&gt;
3527Proxy-Authorization =
3528 &lt;Proxy-Authorization, defined in [Part7], Section 4.3&gt;
3529
3530<x:ref>RWS</x:ref> = &lt;RWS, defined in [Part1], Section 1.2.2&gt;
3531<x:ref>Range</x:ref> = &lt;Range, defined in [Part5], Section 5.4&gt;
3532<x:ref>Reason-Phrase</x:ref> = *( WSP / VCHAR / obs-text )
3533<x:ref>Referer</x:ref> = "Referer:" OWS Referer-v
3534<x:ref>Referer-v</x:ref> = absolute-URI / partial-URI
3535<x:ref>Retry-After</x:ref> = "Retry-After:" OWS Retry-After-v
3536<x:ref>Retry-After-v</x:ref> = HTTP-date / delta-seconds
3537
3538<x:ref>Server</x:ref> = "Server:" OWS Server-v
3539<x:ref>Server-v</x:ref> = product *( RWS ( product / comment ) )
3540<x:ref>Status-Code</x:ref> = "100" / "101" / "200" / "201" / "202" / "203" / "204" /
3541 "205" / "206" / "300" / "301" / "302" / "303" / "304" / "305" /
3542 "307" / "400" / "401" / "402" / "403" / "404" / "405" / "406" /
3543 "407" / "408" / "409" / "410" / "411" / "412" / "413" / "414" /
3544 "415" / "416" / "417" / "500" / "501" / "502" / "503" / "504" /
3545 "505" / extension-code
3546
3547<x:ref>TE</x:ref> = &lt;TE, defined in [Part1], Section 9.5&gt;
3548
3549<x:ref>URI-reference</x:ref> = &lt;URI-reference, defined in [Part1], Section 2.6&gt;
3550<x:ref>User-Agent</x:ref> = "User-Agent:" OWS User-Agent-v
3551<x:ref>User-Agent-v</x:ref> = product *( RWS ( product / comment ) )
3552
3553<x:ref>Vary</x:ref> = &lt;Vary, defined in [Part6], Section 3.5&gt;
3554
3555WWW-Authenticate =
3556 &lt;WWW-Authenticate, defined in [Part7], Section 4.4&gt;
3557
3558<x:ref>absolute-URI</x:ref> = &lt;absolute-URI, defined in [Part1], Section 2.6&gt;
3559
3560<x:ref>comment</x:ref> = &lt;comment, defined in [Part1], Section 3.2&gt;
3561
3562<x:ref>delta-seconds</x:ref> = 1*DIGIT
3563
3564<x:ref>expect-params</x:ref> = ";" token [ "=" ( token / quoted-string ) ]
3565<x:ref>expectation</x:ref> = "100-continue" / expectation-extension
3566<x:ref>expectation-extension</x:ref> = token [ "=" ( token / quoted-string )
3567 *expect-params ]
3568<x:ref>extension-code</x:ref> = 3DIGIT
3569<x:ref>extension-method</x:ref> = token
3570
3571<x:ref>mailbox</x:ref> = &lt;mailbox, defined in [RFC5322], Section 3.4&gt;
3572
3573<x:ref>obs-text</x:ref> = &lt;obs-text, defined in [Part1], Section 1.2.2&gt;
3574
3575<x:ref>partial-URI</x:ref> = &lt;partial-URI, defined in [Part1], Section 2.6&gt;
3576<x:ref>product</x:ref> = &lt;product, defined in [Part1], Section 6.3&gt;
3577
3578<x:ref>quoted-string</x:ref> = &lt;quoted-string, defined in [Part1], Section 1.2.2&gt;
3579
3580<x:ref>request-header</x:ref> = Accept / Accept-Charset / Accept-Encoding /
3581 Accept-Language / Authorization / Expect / From / Host / If-Match /
3582 If-Modified-Since / If-None-Match / If-Range / If-Unmodified-Since /
3583 Max-Forwards / Proxy-Authorization / Range / Referer / TE /
3584 User-Agent
3585<x:ref>response-header</x:ref> = Accept-Ranges / Age / Allow / ETag / Location /
3586 Proxy-Authenticate / Retry-After / Server / Vary / WWW-Authenticate
3587
3588<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 1.2.2&gt;
3589</artwork>
3590</figure>
3591<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
3592; Reason-Phrase defined but not used
3593; Status-Code defined but not used
3594; request-header defined but not used
3595; response-header defined but not used
3596</artwork></figure></section>
3597<?ENDINC p2-semantics.abnf-appendix ?>
3598
3599<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
3600
3601<section title="Since RFC 2616">
3602<t>
3603  Extracted relevant partitions from <xref target="RFC2616"/>.
3604</t>
3605</section>
3606
3607<section title="Since draft-ietf-httpbis-p2-semantics-00">
3608<t>
3609  Closed issues:
3610  <list style="symbols"> 
3611    <t>
3612      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/5"/>:
3613      "Via is a MUST"
3614      (<eref target="http://purl.org/NET/http-errata#via-must"/>)
3615    </t>
3616    <t>
3617      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/6"/>:
3618      "Fragments allowed in Location"
3619      (<eref target="http://purl.org/NET/http-errata#location-fragments"/>)
3620    </t>
3621    <t>
3622      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3623      "Safe Methods vs Redirection"
3624      (<eref target="http://purl.org/NET/http-errata#saferedirect"/>)
3625    </t>
3626    <t>
3627      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/17"/>:
3628      "Revise description of the POST method"
3629      (<eref target="http://purl.org/NET/http-errata#post"/>)
3630    </t>
3631    <t>
3632      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
3633      "Normative and Informative references"
3634    </t>
3635    <t>
3636      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/42"/>:
3637      "RFC2606 Compliance"
3638    </t>
3639    <t>
3640      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/65"/>:
3641      "Informative references"
3642    </t>
3643    <t>
3644      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/84"/>:
3645      "Redundant cross-references"
3646    </t>
3647  </list>
3648</t>
3649<t>
3650  Other changes:
3651  <list style="symbols"> 
3652    <t>
3653      Move definitions of 304 and 412 condition codes to <xref target="Part4"/>
3654    </t>
3655  </list>
3656</t>
3657</section>
3658
3659<section title="Since draft-ietf-httpbis-p2-semantics-01">
3660<t>
3661  Closed issues:
3662  <list style="symbols"> 
3663    <t>
3664      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/21"/>:
3665      "PUT side effects"
3666    </t>
3667    <t>
3668      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/91"/>:
3669      "Duplicate Host header requirements"
3670    </t>
3671  </list>
3672</t>
3673<t>
3674  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3675  <list style="symbols"> 
3676    <t>
3677      Move "Product Tokens" section (back) into Part 1, as "token" is used
3678      in the definition of the Upgrade header field.
3679    </t>
3680    <t>
3681      Add explicit references to BNF syntax and rules imported from other parts of the specification.
3682    </t>
3683    <t>
3684      Copy definition of delta-seconds from Part6 instead of referencing it.
3685    </t>
3686  </list>
3687</t>
3688</section>
3689
3690<section title="Since draft-ietf-httpbis-p2-semantics-02" anchor="changes.since.02">
3691<t>
3692  Closed issues:
3693  <list style="symbols"> 
3694    <t>
3695      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/24"/>:
3696      "Requiring Allow in 405 responses"
3697    </t>
3698    <t>
3699      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/59"/>:
3700      "Status Code Registry"
3701    </t>
3702    <t>
3703      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/61"/>:
3704      "Redirection vs. Location"
3705    </t>
3706    <t>
3707      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/70"/>:
3708      "Cacheability of 303 response"
3709    </t>
3710    <t>
3711      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/76"/>:
3712      "305 Use Proxy"
3713    </t>
3714    <t>
3715      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/105"/>:
3716      "Classification for Allow header"
3717    </t>
3718    <t>
3719      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/112"/>:
3720      "PUT - 'store under' vs 'store at'"
3721    </t>
3722  </list>
3723</t>
3724<t>
3725  Ongoing work on IANA Message Header Field Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
3726  <list style="symbols"> 
3727    <t>
3728      Reference RFC 3984, and update header field registrations for headers defined
3729      in this document.
3730    </t>
3731  </list>
3732</t>
3733<t>
3734  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3735  <list style="symbols"> 
3736    <t>
3737      Replace string literals when the string really is case-sensitive (method).
3738    </t>
3739  </list>
3740</t>
3741</section>
3742
3743<section title="Since draft-ietf-httpbis-p2-semantics-03" anchor="changes.since.03">
3744<t>
3745  Closed issues:
3746  <list style="symbols"> 
3747    <t>
3748      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/98"/>:
3749      "OPTIONS request bodies"
3750    </t>
3751    <t>
3752      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/119"/>:
3753      "Description of CONNECT should refer to RFC2817"
3754    </t>
3755    <t>
3756      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/125"/>:
3757      "Location Content-Location reference request/response mixup"
3758    </t>
3759  </list>
3760</t>
3761<t>
3762  Ongoing work on Method Registry (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/72"/>):
3763  <list style="symbols"> 
3764    <t>
3765      Added initial proposal for registration process, plus initial
3766      content (non-HTTP/1.1 methods to be added by a separate specification).
3767    </t>
3768  </list>
3769</t>
3770</section>
3771
3772<section title="Since draft-ietf-httpbis-p2-semantics-04" anchor="changes.since.04">
3773<t>
3774  Closed issues:
3775  <list style="symbols"> 
3776    <t>
3777      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/103"/>:
3778      "Content-*"
3779    </t>
3780    <t>
3781      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/132"/>:
3782      "RFC 2822 is updated by RFC 5322"
3783    </t>
3784  </list>
3785</t>
3786<t>
3787  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3788  <list style="symbols"> 
3789    <t>
3790      Use "/" instead of "|" for alternatives.
3791    </t>
3792    <t>
3793      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
3794      whitespace ("OWS") and required whitespace ("RWS").
3795    </t>
3796    <t>
3797      Rewrite ABNFs to spell out whitespace rules, factor out
3798      header field value format definitions.
3799    </t>
3800  </list>
3801</t>
3802</section>
3803
3804<section title="Since draft-ietf-httpbis-p2-semantics-05" anchor="changes.since.05">
3805<t>
3806  Closed issues:
3807  <list style="symbols"> 
3808    <t>
3809      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/94"/>:
3810      "Reason-Phrase BNF"
3811    </t>
3812  </list>
3813</t>
3814<t>
3815  Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
3816  <list style="symbols"> 
3817    <t>
3818      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
3819    </t>
3820  </list>
3821</t>
3822</section>
3823
3824<section title="Since draft-ietf-httpbis-p2-semantics-06" anchor="changes.since.06">
3825<t>
3826  Closed issues:
3827  <list style="symbols"> 
3828    <t>
3829      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/144"/>:
3830      "Clarify when Referer is sent"
3831    </t>
3832    <t>
3833      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/164"/>:
3834      "status codes vs methods"
3835    </t>
3836    <t>
3837      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/170"/>:
3838      "Do not require "updates" relation for specs that register status codes or method names"
3839    </t>
3840  </list>
3841</t>
3842</section>
3843
3844<section title="Since draft-ietf-httpbis-p2-semantics-07" anchor="changes.since.07">
3845<t>
3846  Closed issues:
3847  <list style="symbols"> 
3848    <t>
3849      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/27"/>:
3850      "Idempotency"
3851    </t>
3852    <t>
3853      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/33"/>:
3854      "TRACE security considerations"
3855    </t>
3856    <t>
3857      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/110"/>:
3858      "Clarify rules for determining what entities a response carries"
3859    </t>
3860    <t>
3861      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/140"/>:
3862      "update note citing RFC 1945 and 2068"
3863    </t>
3864    <t>
3865      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/182"/>:
3866      "update note about redirect limit"
3867    </t>
3868    <t>
3869      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/191"/>:
3870      "Location header ABNF should use 'URI'"
3871    </t>
3872    <t>
3873      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/192"/>:
3874      "fragments in Location vs status 303"
3875    </t>
3876    <t>
3877      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/198"/>:
3878      "move IANA registrations for optional status codes"
3879    </t>
3880  </list>
3881</t>
3882<t>
3883  Partly resolved issues:
3884  <list style="symbols"> 
3885    <t>
3886      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/171"/>:
3887      "Are OPTIONS and TRACE safe?"
3888    </t>
3889  </list>
3890</t>
3891</section>
3892
3893<section title="Since draft-ietf-httpbis-p2-semantics-08" anchor="changes.since.08">
3894<t>
3895  Closed issues:
3896  <list style="symbols"> 
3897    <t>
3898      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/10"/>:
3899      "Safe Methods vs Redirection" (we missed the introduction to the 3xx
3900      status codes when fixing this previously)
3901    </t>
3902  </list>
3903</t>
3904</section>
3905
3906<section title="Since draft-ietf-httpbis-p2-semantics-09" anchor="changes.since.09">
3907<t>
3908  Closed issues:
3909  <list style="symbols"> 
3910    <t>
3911      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/43"/>:
3912      "Fragment combination / precedence during redirects"
3913    </t>
3914  </list>
3915</t>
3916<t>
3917  Partly resolved issues:
3918  <list style="symbols"> 
3919    <t>
3920      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/185"/>:
3921      "Location header payload handling"
3922    </t>
3923    <t>
3924      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/196"/>:
3925      "Term for the requested resource's URI"
3926    </t>
3927  </list>
3928</t>
3929</section>
3930
3931<section title="Since draft-ietf-httpbis-p2-semantics-10" anchor="changes.since.10">
3932<t>
3933  Closed issues:
3934  <list style="symbols"> 
3935    <t>
3936      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/69"/>:
3937      "Clarify 'Requested Variant'"
3938    </t>
3939    <t>
3940      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/109"/>:
3941      "Clarify entity / representation / variant terminology"
3942    </t>
3943    <t>
3944      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/139"/>:
3945      "Methods and Caching"
3946    </t>
3947    <t>
3948      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/190"/>:
3949      "OPTIONS vs Max-Forwards"
3950    </t>
3951    <t>
3952      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/199"/>:
3953      "Status codes and caching"
3954    </t>
3955    <t>
3956      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>:
3957      "consider removing the 'changes from 2068' sections"
3958    </t>
3959  </list>
3960</t>
3961</section>
3962
3963<section title="Since draft-ietf-httpbis-p2-semantics-11" anchor="changes.since.11">
3964<t>
3965  Closed issues:
3966  <list style="symbols"> 
3967    <t>
3968      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/229"/>:
3969      "Considerations for new status codes"
3970    </t>
3971    <t>
3972      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/230"/>:
3973      "Considerations for new methods"
3974    </t>
3975    <t>
3976      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/232"/>:
3977      "User-Agent guidelines" (relating to the 'User-Agent' header field)
3978    </t>
3979  </list>
3980</t>
3981</section>
3982
3983<section title="Since draft-ietf-httpbis-p2-semantics-12" anchor="changes.since.12">
3984<t>
3985  Closed issues:
3986  <list style="symbols"> 
3987    <t>
3988      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/88"/>:
3989      "205 Bodies"
3990    </t>
3991    <t>
3992      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/239"/>:
3993      "Migrate CONNECT from RFC2817 to p2"
3994    </t>
3995  </list>
3996</t>
3997</section>
3998
3999</section>
4000
4001</back>
4002</rfc>
Note: See TracBrowser for help on using the repository browser.