source: draft-ietf-httpbis/latest/p5-range.xml @ 926

Last change on this file since 926 was 926, checked in by ylafon@…, 9 years ago

uniform use of 'status' (see #234)

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1<?xml version="1.0" encoding="utf-8"?>
2<?xml-stylesheet type='text/xsl' href='../myxml2rfc.xslt'?>
3<!DOCTYPE rfc [
4  <!ENTITY MAY "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MAY</bcp14>">
5  <!ENTITY MUST "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST</bcp14>">
6  <!ENTITY MUST-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>MUST NOT</bcp14>">
7  <!ENTITY OPTIONAL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>OPTIONAL</bcp14>">
8  <!ENTITY RECOMMENDED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>RECOMMENDED</bcp14>">
9  <!ENTITY REQUIRED "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>REQUIRED</bcp14>">
10  <!ENTITY SHALL "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL</bcp14>">
11  <!ENTITY SHALL-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHALL NOT</bcp14>">
12  <!ENTITY SHOULD "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD</bcp14>">
13  <!ENTITY SHOULD-NOT "<bcp14 xmlns='http://purl.org/net/xml2rfc/ext'>SHOULD NOT</bcp14>">
14  <!ENTITY ID-VERSION "latest">
15  <!ENTITY ID-MONTH "July">
16  <!ENTITY ID-YEAR "2010">
17  <!ENTITY notation                   "<xref target='Part1' x:rel='#notation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
18  <!ENTITY notation-abnf              "<xref target='Part1' x:rel='#notation.abnf' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
19  <!ENTITY basic-rules                "<xref target='Part1' x:rel='#basic.rules' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
20  <!ENTITY full-date                  "<xref target='Part1' x:rel='#date.time.formats.full.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
21  <!ENTITY messaging                  "<xref target='Part1' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
22  <!ENTITY entity-tags                "<xref target='Part4' x:rel='#entity.tags' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
23  <!ENTITY weak-and-strong-validators "<xref target='Part4' x:rel='#weak.and.strong.validators' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
24]>
25<?rfc toc="yes" ?>
26<?rfc symrefs="yes" ?>
27<?rfc sortrefs="yes" ?>
28<?rfc compact="yes"?>
29<?rfc subcompact="no" ?>
30<?rfc linkmailto="no" ?>
31<?rfc editing="no" ?>
32<?rfc comments="yes"?>
33<?rfc inline="yes"?>
34<?rfc rfcedstyle="yes"?>
35<?rfc-ext allow-markup-in-artwork="yes" ?>
36<?rfc-ext include-references-in-index="yes" ?>
37<rfc obsoletes="2616" category="std" x:maturity-level="draft"
38     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p5-range-&ID-VERSION;"     xmlns:x='http://purl.org/net/xml2rfc/ext'>
39<front>
40
41  <title abbrev="HTTP/1.1, Part 5">HTTP/1.1, part 5: Range Requests and Partial Responses</title>
42
43  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
44    <organization abbrev="Day Software">Day Software</organization>
45    <address>
46      <postal>
47        <street>23 Corporate Plaza DR, Suite 280</street>
48        <city>Newport Beach</city>
49        <region>CA</region>
50        <code>92660</code>
51        <country>USA</country>
52      </postal>
53      <phone>+1-949-706-5300</phone>
54      <facsimile>+1-949-706-5305</facsimile>
55      <email>fielding@gbiv.com</email>
56      <uri>http://roy.gbiv.com/</uri>
57    </address>
58  </author>
59
60  <author initials="J." surname="Gettys" fullname="Jim Gettys">
61    <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
62    <address>
63      <postal>
64        <street>21 Oak Knoll Road</street>
65        <city>Carlisle</city>
66        <region>MA</region>
67        <code>01741</code>
68        <country>USA</country>
69      </postal>
70      <email>jg@freedesktop.org</email>
71      <uri>http://gettys.wordpress.com/</uri>
72    </address>
73  </author>
74 
75  <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
76    <organization abbrev="HP">Hewlett-Packard Company</organization>
77    <address>
78      <postal>
79        <street>HP Labs, Large Scale Systems Group</street>
80        <street>1501 Page Mill Road, MS 1177</street>
81        <city>Palo Alto</city>
82        <region>CA</region>
83        <code>94304</code>
84        <country>USA</country>
85      </postal>
86      <email>JeffMogul@acm.org</email>
87    </address>
88  </author>
89
90  <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
91    <organization abbrev="Microsoft">Microsoft Corporation</organization>
92    <address>
93      <postal>
94        <street>1 Microsoft Way</street>
95        <city>Redmond</city>
96        <region>WA</region>
97        <code>98052</code>
98        <country>USA</country>
99      </postal>
100      <email>henrikn@microsoft.com</email>
101    </address>
102  </author>
103
104  <author initials="L." surname="Masinter" fullname="Larry Masinter">
105    <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
106    <address>
107      <postal>
108        <street>345 Park Ave</street>
109        <city>San Jose</city>
110        <region>CA</region>
111        <code>95110</code>
112        <country>USA</country>
113      </postal>
114      <email>LMM@acm.org</email>
115      <uri>http://larry.masinter.net/</uri>
116    </address>
117  </author>
118 
119  <author initials="P." surname="Leach" fullname="Paul J. Leach">
120    <organization abbrev="Microsoft">Microsoft Corporation</organization>
121    <address>
122      <postal>
123        <street>1 Microsoft Way</street>
124        <city>Redmond</city>
125        <region>WA</region>
126        <code>98052</code>
127      </postal>
128      <email>paulle@microsoft.com</email>
129    </address>
130  </author>
131   
132  <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
133    <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
134    <address>
135      <postal>
136        <street>MIT Computer Science and Artificial Intelligence Laboratory</street>
137        <street>The Stata Center, Building 32</street>
138        <street>32 Vassar Street</street>
139        <city>Cambridge</city>
140        <region>MA</region>
141        <code>02139</code>
142        <country>USA</country>
143      </postal>
144      <email>timbl@w3.org</email>
145      <uri>http://www.w3.org/People/Berners-Lee/</uri>
146    </address>
147  </author>
148
149  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
150    <organization abbrev="W3C">World Wide Web Consortium</organization>
151    <address>
152      <postal>
153        <street>W3C / ERCIM</street>
154        <street>2004, rte des Lucioles</street>
155        <city>Sophia-Antipolis</city>
156        <region>AM</region>
157        <code>06902</code>
158        <country>France</country>
159      </postal>
160      <email>ylafon@w3.org</email>
161      <uri>http://www.raubacapeu.net/people/yves/</uri>
162    </address>
163  </author>
164
165  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
166    <organization abbrev="greenbytes">greenbytes GmbH</organization>
167    <address>
168      <postal>
169        <street>Hafenweg 16</street>
170        <city>Muenster</city><region>NW</region><code>48155</code>
171        <country>Germany</country>
172      </postal>
173      <phone>+49 251 2807760</phone>
174      <facsimile>+49 251 2807761</facsimile>
175      <email>julian.reschke@greenbytes.de</email>
176      <uri>http://greenbytes.de/tech/webdav/</uri>
177    </address>
178  </author>
179
180  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
181  <workgroup>HTTPbis Working Group</workgroup>
182
183<abstract>
184<t>
185   The Hypertext Transfer Protocol (HTTP) is an application-level
186   protocol for distributed, collaborative, hypermedia information
187   systems. HTTP has been in use by the World Wide Web global information
188   initiative since 1990. This document is Part 5 of the seven-part specification
189   that defines the protocol referred to as "HTTP/1.1" and, taken together,
190   obsoletes RFC 2616.  Part 5 defines range-specific requests and
191   the rules for constructing and combining responses to those requests.
192</t>
193</abstract>
194
195<note title="Editorial Note (To be removed by RFC Editor)">
196  <t>
197    Discussion of this draft should take place on the HTTPBIS working group
198    mailing list (ietf-http-wg@w3.org). The current issues list is
199    at <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/>
200    and related documents (including fancy diffs) can be found at
201    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
202  </t>
203  <t>
204    The changes in this draft are summarized in <xref target="changes.since.10"/>.
205  </t>
206</note>
207</front>
208<middle>
209<section title="Introduction" anchor="introduction">
210<t>
211   HTTP clients often encounter interrupted data transfers as a result
212   of cancelled requests or dropped connections.  When a cache has stored
213   a partial representation, it is desirable to request the remainder
214   of that representation in a subsequent request rather than transfer
215   the entire representation.
216   There are also a number of Web applications that benefit from being
217   able to request only a subset of a larger representation, such as a
218   single page of a very large document or only part of an image to be
219   rendered by a device with limited local storage.
220</t>
221<t>
222   This document defines HTTP/1.1 range requests,
223   partial responses, and the multipart/byteranges media type.
224   The protocol for range requests is an &OPTIONAL; feature of HTTP,
225   designed so resources or recipients that do not implement this feature
226   can respond as if it is a normal GET request without impacting
227   interoperability.  Partial responses are indicated by a distinct status
228   code to not be mistaken for full responses by intermediate caches
229   that might not implement the feature.
230</t>
231<t>
232   Although the HTTP range request mechanism is designed to allow for
233   extensible range types, this specification only defines requests for
234   byte ranges.
235</t>
236
237<section title="Requirements" anchor="intro.requirements">
238<t>
239   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
240   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
241   document are to be interpreted as described in <xref target="RFC2119"/>.
242</t>
243<t>
244   An implementation is not compliant if it fails to satisfy one or more
245   of the "MUST" or "REQUIRED" level requirements for the protocols it
246   implements. An implementation that satisfies all the "MUST" or "REQUIRED"
247   level and all the "SHOULD" level requirements for its protocols is said
248   to be "unconditionally compliant"; one that satisfies all the "MUST"
249   level requirements but not all the "SHOULD" level requirements for its
250   protocols is said to be "conditionally compliant".
251</t>
252</section>
253
254<section title="Syntax Notation" anchor="notation">
255  <x:anchor-alias value="ALPHA"/>
256  <x:anchor-alias value="CHAR"/>
257  <x:anchor-alias value="CR"/>
258  <x:anchor-alias value="DIGIT"/>
259  <x:anchor-alias value="LF"/>
260  <x:anchor-alias value="OCTET"/>
261  <x:anchor-alias value="SP"/>
262  <x:anchor-alias value="VCHAR"/>
263  <x:anchor-alias value="WSP"/>
264<t>
265  This specification uses the ABNF syntax defined in &notation; (which
266  extends the syntax defined in <xref target="RFC5234"/> with a list rule).
267  <xref target="collected.abnf"/> shows the collected ABNF, with the list
268  rule expanded.
269</t>
270<t>
271  The following core rules are included by
272  reference, as defined in <xref target="RFC5234" x:fmt="," x:sec="B.1"/>:
273  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
274  DIGIT (decimal 0-9), DQUOTE (double quote),
275  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
276  OCTET (any 8-bit sequence of data), SP (space),
277  VCHAR (any visible USASCII character),
278  and WSP (whitespace).
279</t>
280
281<section title="Core Rules" anchor="core.rules">
282  <x:anchor-alias value="token"/>
283  <x:anchor-alias value="OWS"/>
284<t>
285  The core rules below are defined in &basic-rules;:
286</t>
287<figure><artwork type="abnf2616">
288  <x:ref>token</x:ref>      = &lt;token, defined in &basic-rules;&gt;
289  <x:ref>OWS</x:ref>        = &lt;OWS, defined in &basic-rules;&gt;
290</artwork></figure>
291</section>
292
293<section title="ABNF Rules defined in other Parts of the Specification" anchor="abnf.dependencies">
294  <x:anchor-alias value="entity-tag"/>
295  <x:anchor-alias value="HTTP-date"/>
296<t>
297  The ABNF rules below are defined in other parts:
298</t>
299<figure><!--Part1--><artwork type="abnf2616">
300  <x:ref>HTTP-date</x:ref>  = &lt;HTTP-date, defined in &full-date;&gt;
301</artwork></figure>
302<figure><!--Part4--><artwork type="abnf2616">
303  <x:ref>entity-tag</x:ref> = &lt;entity-tag, defined in &entity-tags;&gt;
304</artwork></figure>
305</section>
306
307</section>
308
309</section>
310
311
312<section title="Range Units" anchor="range.units">
313  <x:anchor-alias value="bytes-unit"/>
314  <x:anchor-alias value="other-range-unit"/>
315  <x:anchor-alias value="range-unit"/>
316<t>
317   HTTP/1.1 allows a client to request that only part (a range of) the
318   representation be included within the response. HTTP/1.1 uses range
319   units in the Range (<xref target="header.range"/>) and Content-Range (<xref target="header.content-range"/>)
320   header fields. A representation can be broken down into subranges according
321   to various structural units.
322</t>
323<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="range-unit"/><iref primary="true" item="Grammar" subitem="bytes-unit"/><iref primary="true" item="Grammar" subitem="other-range-unit"/>
324  <x:ref>range-unit</x:ref>       = <x:ref>bytes-unit</x:ref> / <x:ref>other-range-unit</x:ref>
325  <x:ref>bytes-unit</x:ref>       = "bytes"
326  <x:ref>other-range-unit</x:ref> = <x:ref>token</x:ref>
327</artwork></figure>
328<t>
329  HTTP/1.1 has been designed to allow implementations of applications
330  that do not depend on knowledge of ranges. The only range unit defined
331  by HTTP/1.1 is "bytes".
332</t>
333<t>
334  If a range unit is not understood in a request, a server &MUST; ignore
335  the whole Range header (<xref target="header.range" />).
336  If a range unit is not understood in a response, an intermediary
337  &SHOULD; pass the response to the client; a client &MUST; fail.
338</t>
339</section>
340
341<section title="Status Code Definitions" anchor="status.code.definitions">
342<section title="206 Partial Content" anchor="status.206">
343  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
344  <iref primary="true" item="Status Codes" subitem="206 Partial Content" x:for-anchor=""/>
345<t>
346   The server has fulfilled the partial GET request for the resource.
347   The request &MUST; have included a Range header field (<xref target="header.range"/>)
348   indicating the desired range, and &MAY; have included an If-Range
349   header field (<xref target="header.if-range"/>) to make the request conditional.
350</t>
351<t>
352   The response &MUST; include the following header fields:
353  <list style="symbols">
354    <t>
355        Either a Content-Range header field (<xref target="header.content-range"/>) indicating
356        the range included with this response, or a multipart/byteranges
357        Content-Type including Content-Range fields for each part. If a
358        Content-Length header field is present in the response, its
359        value &MUST; match the actual number of octets transmitted in the
360        message-body.
361    </t>
362    <t>
363        Date
364    </t>
365    <t>
366        Cache-Control, ETag, Expires, Content-Location, Last-Modified,
367        and/or Vary, if the header field would have been sent in a 200
368        response to the same request
369    </t>
370  </list>
371</t>
372<t>
373   If the 206 response is the result of an If-Range request, the response
374   &SHOULD-NOT; include other entity-headers. Otherwise, the response
375   &MUST; include all of the entity-headers that would have been returned
376   with a 200 (OK) response to the same request.
377</t>
378<t>
379   A cache &MUST-NOT; combine a 206 response with other previously cached
380   content if the ETag or Last-Modified headers do not match exactly,
381   see <xref target="combining.byte.ranges"/>.
382</t>
383<t>
384   A cache that does not support the Range and Content-Range headers
385   &MUST-NOT; cache 206 (Partial Content) responses. Furthermore,
386   if a response uses a range unit that is not understood by the cache,
387   then it &MUST-NOT; be cached either.
388</t>
389</section>
390
391<section title="416 Requested Range Not Satisfiable" anchor="status.416">
392  <iref primary="true" item="416 Requested Range Not Satisfiable (status code)" x:for-anchor=""/>
393  <iref primary="true" item="Status Codes" subitem="416 Requested Range Not Satisfiable" x:for-anchor=""/>
394<t>
395   A server &SHOULD; return a response with this status code if a request
396   included a Range request-header field (<xref target="header.range"/>), and none of
397   the ranges-specifier values in this field overlap the current extent
398   of the selected resource, and the request did not include an If-Range
399   request-header field (<xref target="header.if-range"/>). (For byte-ranges,
400   this means that the first-byte-pos of all of the byte-range-spec values were
401   greater than the current length of the selected resource.)
402</t>
403<t>
404   When this status code is returned for a byte-range request, the
405   response &SHOULD; include a Content-Range entity-header field
406   specifying the current length of the selected resource (see <xref target="header.content-range"/>).
407   This response &MUST-NOT; use the multipart/byteranges content-type.
408</t>
409</section>
410</section>
411
412<section title="Combining Ranges" anchor="combining.byte.ranges">
413<t>
414   A response might transfer only a subrange of a representation, either because
415   the request included one or more Range specifications, or because
416   a connection closed prematurely.
417   After several such transfers, a cache might have received several
418   ranges of the same representation.
419</t>
420<t>
421   If a cache has a stored non-empty set of subranges for a representation, and
422   an incoming response transfers another subrange, the cache &MAY;
423   combine the new subrange with the existing set if both the following
424   conditions are met:
425  <list style="symbols">
426    <t>Both the incoming response and the cache entry have a cache
427        validator.</t>
428    <t>The two cache validators match using the strong comparison
429        function (see &weak-and-strong-validators;).</t>
430  </list>
431</t>
432<t>
433   If either requirement is not met, the cache &MUST; use only the most
434   recent partial response (based on the Date values transmitted with
435   every response, and using the incoming response if these values are
436   equal or missing), and &MUST; discard the other partial information.
437</t>
438</section>
439
440<section title="Header Field Definitions" anchor="header.fields">
441<t>
442   This section defines the syntax and semantics of HTTP/1.1 header fields
443   related to range requests and partial responses.
444</t>
445<t>
446   For entity-header fields, both sender and recipient refer to either the
447   client or the server, depending on who sends and who receives the message.
448</t>
449
450<section title="Accept-Ranges" anchor="header.accept-ranges">
451  <iref primary="true" item="Accept-Ranges header" x:for-anchor=""/>
452  <iref primary="true" item="Headers" subitem="Accept-Ranges" x:for-anchor=""/>
453  <x:anchor-alias value="Accept-Ranges"/>
454  <x:anchor-alias value="Accept-Ranges-v"/>
455  <x:anchor-alias value="acceptable-ranges"/>
456<t>
457   The "Accept-Ranges" response-header field allows a resource to indicate
458   its acceptance of range requests.
459</t>
460<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Ranges"/><iref primary="true" item="Grammar" subitem="Accept-Ranges-v"/><iref primary="true" item="Grammar" subitem="acceptable-ranges"/>
461  <x:ref>Accept-Ranges</x:ref>     = "Accept-Ranges" ":" <x:ref>OWS</x:ref> <x:ref>Accept-Ranges-v</x:ref>
462  <x:ref>Accept-Ranges-v</x:ref>   = <x:ref>acceptable-ranges</x:ref>
463  <x:ref>acceptable-ranges</x:ref> = 1#<x:ref>range-unit</x:ref> / "none"
464</artwork></figure>
465<t>
466      Origin servers that accept byte-range requests &MAY; send
467</t>
468<figure><artwork type="example">
469  Accept-Ranges: bytes
470</artwork></figure>
471<t>
472      but are not required to do so. Clients &MAY; generate range
473      requests without having received this header for the resource
474      involved. Range units are defined in <xref target="range.units"/>.
475</t>
476<t>
477      Servers that do not accept any kind of range request for a
478      resource &MAY; send
479</t>
480<figure><artwork type="example">
481  Accept-Ranges: none
482</artwork></figure>
483<t>
484      to advise the client not to attempt a range request.
485</t>
486</section>
487
488<section title="Content-Range" anchor="header.content-range">
489  <iref primary="true" item="Content-Range header" x:for-anchor=""/>
490  <iref primary="true" item="Headers" subitem="Content-Range" x:for-anchor=""/>
491  <x:anchor-alias value="byte-content-range-spec"/>
492  <x:anchor-alias value="byte-range-resp-spec"/>
493  <x:anchor-alias value="Content-Range"/>
494  <x:anchor-alias value="Content-Range-v"/>
495  <x:anchor-alias value="content-range-spec"/>
496  <x:anchor-alias value="instance-length"/>
497  <x:anchor-alias value="other-content-range-spec"/>
498  <x:anchor-alias value="other-range-resp-spec"/>
499<t>
500   The "Content-Range" entity-header field is sent with a partial representation to
501   specify where in the full representation the partial body should be
502   applied. Range units are defined in <xref target="range.units"/>.
503</t>
504<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Range"/><iref primary="true" item="Grammar" subitem="Content-Range-v"/><iref primary="true" item="Grammar" subitem="content-range-spec"/><iref primary="true" item="Grammar" subitem="byte-content-range-spec"/><iref primary="true" item="Grammar" subitem="byte-range-resp-spec"/><iref primary="true" item="Grammar" subitem="instance-length"/>
505  <x:ref>Content-Range</x:ref> = "Content-Range" ":" <x:ref>OWS</x:ref> <x:ref>Content-Range-v</x:ref>
506  <x:ref>Content-Range-v</x:ref> = <x:ref>content-range-spec</x:ref>
507 
508  <x:ref>content-range-spec</x:ref>      = <x:ref>byte-content-range-spec</x:ref>
509                          / <x:ref>other-content-range-spec</x:ref>
510  <x:ref>byte-content-range-spec</x:ref> = <x:ref>bytes-unit</x:ref> <x:ref>SP</x:ref>
511                            <x:ref>byte-range-resp-spec</x:ref> "/"
512                            ( <x:ref>instance-length</x:ref> / "*" )
513 
514  <x:ref>byte-range-resp-spec</x:ref>    = (<x:ref>first-byte-pos</x:ref> "-" <x:ref>last-byte-pos</x:ref>)
515                          / "*"
516                         
517  <x:ref>instance-length</x:ref>         = 1*<x:ref>DIGIT</x:ref>
518 
519  <x:ref>other-content-range-spec</x:ref> = <x:ref>other-range-unit</x:ref> <x:ref>SP</x:ref>
520                             <x:ref>other-range-resp-spec</x:ref>
521  <x:ref>other-range-resp-spec</x:ref>    = *<x:ref>CHAR</x:ref>
522</artwork></figure>
523<t>
524   The header &SHOULD; indicate the total length of the full representation,
525   unless this length is unknown or difficult to determine. The asterisk
526   "*" character means that the instance-length is unknown at the time
527   when the response was generated.
528</t>
529<t>
530   Unlike byte-ranges-specifier values (see <xref target="byte.ranges"/>), a byte-range-resp-spec
531   &MUST; only specify one range, and &MUST; contain
532   absolute byte positions for both the first and last byte of the
533   range.
534</t>
535<t>
536   A byte-content-range-spec with a byte-range-resp-spec whose last-byte-pos
537   value is less than its first-byte-pos value, or whose
538   instance-length value is less than or equal to its last-byte-pos
539   value, is invalid. The recipient of an invalid byte-content-range-spec
540   &MUST; ignore it and any content transferred along with it.
541</t>
542<t>
543   In the case of a byte range request:
544   A server sending a response with status code 416 (Requested range not
545   satisfiable) &SHOULD; include a Content-Range field with a byte-range-resp-spec
546   of "*". The instance-length specifies the current length of
547   the selected resource. A response with status code 206 (Partial
548   Content) &MUST-NOT; include a Content-Range field with a byte-range-resp-spec of "*".
549</t>
550<t>
551   Examples of byte-content-range-spec values, assuming that the representation
552   contains a total of 1234 bytes:
553   <list style="symbols">
554      <t>
555        The first 500 bytes:
556<figure><artwork type="example" x:indent-with="   ">
557  bytes 0-499/1234
558</artwork></figure>
559      </t>   
560      <t>
561        The second 500 bytes:
562<figure><artwork type="example" x:indent-with="   ">
563  bytes 500-999/1234
564</artwork></figure>
565      </t>   
566      <t>
567        All except for the first 500 bytes:
568<figure><artwork type="example" x:indent-with="   ">
569  bytes 500-1233/1234
570</artwork></figure>
571      </t>   
572      <t>
573        The last 500 bytes:
574<figure><artwork type="example" x:indent-with="   ">
575  bytes 734-1233/1234
576</artwork></figure>
577      </t>   
578   </list>
579</t>
580<t>
581   When an HTTP message includes the content of a single range (for
582   example, a response to a request for a single range, or to a request
583   for a set of ranges that overlap without any holes), this content is
584   transmitted with a Content-Range header, and a Content-Length header
585   showing the number of bytes actually transferred. For example,
586</t>
587<figure><artwork type="example">
588  HTTP/1.1 206 Partial Content
589  Date: Wed, 15 Nov 1995 06:25:24 GMT
590  Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
591  Content-Range: bytes 21010-47021/47022
592  Content-Length: 26012
593  Content-Type: image/gif
594</artwork></figure>
595<t>
596   When an HTTP message includes the content of multiple ranges (for
597   example, a response to a request for multiple non-overlapping
598   ranges), these are transmitted as a multipart message. The multipart
599   media type used for this purpose is "multipart/byteranges" as defined
600   in <xref target="internet.media.type.multipart.byteranges"/>.
601</t>
602<t>
603   A response to a request for a single range &MUST-NOT; be sent using the
604   multipart/byteranges media type.  A response to a request for
605   multiple ranges, whose result is a single range, &MAY; be sent as a
606   multipart/byteranges media type with one part. A client that cannot
607   decode a multipart/byteranges message &MUST-NOT; ask for multiple
608   ranges in a single request.
609</t>
610<t>
611   When a client requests multiple ranges in one request, the
612   server &SHOULD; return them in the order that they appeared in the
613   request.
614</t>
615<t>
616   If the server ignores a byte-range-spec because it is syntactically
617   invalid, the server &SHOULD; treat the request as if the invalid Range
618   header field did not exist. (Normally, this means return a 200
619   response containing the full representation).
620</t>
621<t>
622   If the server receives a request (other than one including an If-Range
623   request-header field) with an unsatisfiable Range request-header
624   field (that is, all of whose byte-range-spec values have a
625   first-byte-pos value greater than the current length of the selected
626   resource), it &SHOULD; return a response code of 416 (Requested range
627   not satisfiable) (<xref target="status.416"/>).
628</t>
629<x:note>
630  <t>
631    <x:h>Note:</x:h> Clients cannot depend on servers to send a 416 (Requested
632    range not satisfiable) response instead of a 200 (OK) response for
633    an unsatisfiable Range request-header, since not all servers
634    implement this request-header.
635  </t>
636</x:note>
637</section>
638
639<section title="If-Range" anchor="header.if-range">
640  <iref primary="true" item="If-Range header" x:for-anchor=""/>
641  <iref primary="true" item="Headers" subitem="If-Range" x:for-anchor=""/>
642  <x:anchor-alias value="If-Range"/>
643  <x:anchor-alias value="If-Range-v"/>
644<t>
645   If a client has a partial copy of a representation in its cache, and wishes
646   to have an up-to-date copy of the entire representation in its cache, it
647   could use the Range request-header with a conditional GET (using
648   either or both of If-Unmodified-Since and If-Match.) However, if the
649   condition fails because the representation has been modified, the client
650   would then have to make a second request to obtain the entire current
651   representation.
652</t>
653<t>
654   The "If-Range" request-header field allows a client to "short-circuit" the second
655   request. Informally, its meaning is "if the representation is unchanged, send
656   me the part(s) that I am missing; otherwise, send me the entire new
657   representation".
658</t>
659<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="If-Range"/><iref primary="true" item="Grammar" subitem="If-Range-v"/>
660  <x:ref>If-Range</x:ref>   = "If-Range" ":" <x:ref>OWS</x:ref> <x:ref>If-Range-v</x:ref>
661  <x:ref>If-Range-v</x:ref> = <x:ref>entity-tag</x:ref> / <x:ref>HTTP-date</x:ref>
662</artwork></figure>
663<t>
664   If the client has no entity-tag for a representation, but does have a Last-Modified
665   date, it &MAY; use that date in an If-Range header. (The
666   server can distinguish between a valid HTTP-date and any form of
667   entity-tag by examining no more than two characters.) The If-Range
668   header &SHOULD; only be used together with a Range header, and &MUST; be
669   ignored if the request does not include a Range header, or if the
670   server does not support the sub-range operation.
671</t>
672<t>
673   If the entity-tag given in the If-Range header matches the current
674   cache validator for the representation, then the server &SHOULD; provide the
675   specified sub-range of the representation using a 206 (Partial Content)
676   response. If the cache validator does not match, then the server &SHOULD;
677   return the entire representation using a 200 (OK) response.
678</t>
679</section>
680
681<section title="Range" anchor="header.range">
682  <iref primary="true" item="Range header" x:for-anchor=""/>
683  <iref primary="true" item="Headers" subitem="Range" x:for-anchor=""/>
684
685<section title="Byte Ranges" anchor="byte.ranges">
686<t>
687   Since all HTTP representations are transferred as sequences
688   of bytes, the concept of a byte range is meaningful for any HTTP
689   representation. (However, not all clients and servers need to support byte-range
690   operations.)
691</t>
692<t>
693   Byte range specifications in HTTP apply to the sequence of bytes in
694   the representation body (not necessarily the same as the message-body).
695</t>
696<t anchor="rule.ranges-specifier">
697  <x:anchor-alias value="byte-range-set"/>
698  <x:anchor-alias value="byte-range-spec"/>
699  <x:anchor-alias value="byte-ranges-specifier"/>
700  <x:anchor-alias value="first-byte-pos"/>
701  <x:anchor-alias value="last-byte-pos"/>
702  <x:anchor-alias value="ranges-specifier"/>
703  <x:anchor-alias value="suffix-byte-range-spec"/>
704  <x:anchor-alias value="suffix-length"/>
705
706   A byte range operation &MAY; specify a single range of bytes, or a set
707   of ranges within a single representation.
708</t>
709<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="ranges-specifier"/><iref primary="true" item="Grammar" subitem="byte-ranges-specifier"/><iref primary="true" item="Grammar" subitem="byte-range-set"/><iref primary="true" item="Grammar" subitem="byte-range-spec"/><iref primary="true" item="Grammar" subitem="first-byte-pos"/><iref primary="true" item="Grammar" subitem="last-byte-pos"/>
710  <x:ref>byte-ranges-specifier</x:ref> = <x:ref>bytes-unit</x:ref> "=" <x:ref>byte-range-set</x:ref>
711  <x:ref>byte-range-set</x:ref>  = 1#( <x:ref>byte-range-spec</x:ref> / <x:ref>suffix-byte-range-spec</x:ref> )
712  <x:ref>byte-range-spec</x:ref> = <x:ref>first-byte-pos</x:ref> "-" [ <x:ref>last-byte-pos</x:ref> ]
713  <x:ref>first-byte-pos</x:ref>  = 1*<x:ref>DIGIT</x:ref>
714  <x:ref>last-byte-pos</x:ref>   = 1*<x:ref>DIGIT</x:ref>
715</artwork></figure>
716<t>
717   The first-byte-pos value in a byte-range-spec gives the byte-offset
718   of the first byte in a range. The last-byte-pos value gives the
719   byte-offset of the last byte in the range; that is, the byte
720   positions specified are inclusive. Byte offsets start at zero.
721</t>
722<t>
723   If the last-byte-pos value is present, it &MUST; be greater than or
724   equal to the first-byte-pos in that byte-range-spec, or the byte-range-spec
725   is syntactically invalid. The recipient of a byte-range-set
726   that includes one or more syntactically invalid byte-range-spec
727   values &MUST; ignore the header field that includes that byte-range-set.
728</t>
729<t>
730   If the last-byte-pos value is absent, or if the value is greater than
731   or equal to the current length of the representation body, last-byte-pos is
732   taken to be equal to one less than the current length of the representation
733   in bytes.
734</t>
735<t>
736   By its choice of last-byte-pos, a client can limit the number of
737   bytes retrieved without knowing the size of the representation.
738</t>
739<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="suffix-byte-range-spec"/><iref primary="true" item="Grammar" subitem="suffix-length"/>
740  <x:ref>suffix-byte-range-spec</x:ref> = "-" <x:ref>suffix-length</x:ref>
741  <x:ref>suffix-length</x:ref> = 1*<x:ref>DIGIT</x:ref>
742</artwork></figure>
743<t>
744   A suffix-byte-range-spec is used to specify the suffix of the
745   representation body, of a length given by the suffix-length value. (That is,
746   this form specifies the last N bytes of a representation.) If the
747   representation is shorter than the specified suffix-length, the entire
748   representation is used.
749</t>
750<t>
751   If a syntactically valid byte-range-set includes at least one byte-range-spec
752   whose first-byte-pos is less than the current length of
753   the representation, or at least one suffix-byte-range-spec with a non-zero
754   suffix-length, then the byte-range-set is satisfiable.
755   Otherwise, the byte-range-set is unsatisfiable. If the byte-range-set
756   is unsatisfiable, the server &SHOULD; return a response with a
757   416 (Requested range not satisfiable) status code. Otherwise, the server
758   &SHOULD; return a response with a 206 (Partial Content) status code
759   containing the satisfiable ranges of the representation.
760</t>
761<t>
762   Examples of byte-ranges-specifier values (assuming a representation of
763   length 10000):
764  <list style="symbols">
765     <t>The first 500 bytes (byte offsets 0-499, inclusive):
766<figure><artwork type="example" x:indent-with="   ">
767  bytes=0-499
768</artwork></figure>
769    </t>
770     <t>The second 500 bytes (byte offsets 500-999, inclusive):
771<figure><artwork type="example" x:indent-with="   ">
772  bytes=500-999
773</artwork></figure>
774    </t>
775     <t>The final 500 bytes (byte offsets 9500-9999, inclusive):
776<figure><artwork type="example" x:indent-with="   ">
777  bytes=-500
778</artwork></figure>
779    Or:
780<figure><artwork type="example" x:indent-with="   ">
781  bytes=9500-
782</artwork></figure>
783    </t>
784     <t>The first and last bytes only (bytes 0 and 9999):
785<figure><artwork type="example" x:indent-with="   ">
786  bytes=0-0,-1
787</artwork></figure>
788     </t>
789     <t>Several legal but not canonical specifications of the second 500
790        bytes (byte offsets 500-999, inclusive):
791<figure><artwork type="example" x:indent-with="   ">
792  bytes=500-600,601-999
793  bytes=500-700,601-999
794</artwork></figure>
795     </t>
796  </list>
797</t>
798</section>
799
800<section title="Range Retrieval Requests" anchor="range.retrieval.requests">
801  <x:anchor-alias value="Range"/>
802  <x:anchor-alias value="Range-v"/>
803  <x:anchor-alias value="other-ranges-specifier"/>
804  <x:anchor-alias value="other-range-set"/>
805<t>
806   The "Range" request-header field defines the GET method (conditional or
807   not) to request one or more sub-ranges of the response representation body, instead
808   of the entire representation body.
809</t>
810<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Range"/>
811  <x:ref>Range</x:ref>   = "Range" ":" <x:ref>OWS</x:ref> <x:ref>Range-v</x:ref>
812  <x:ref>Range-v</x:ref> = <x:ref>byte-ranges-specifier</x:ref>
813          / <x:ref>other-ranges-specifier</x:ref>
814  <x:ref>other-ranges-specifier</x:ref> = <x:ref>other-range-unit</x:ref> "=" <x:ref>other-range-set</x:ref>
815  <x:ref>other-range-set</x:ref> = 1*<x:ref>CHAR</x:ref>
816</artwork></figure>
817<t>
818   A server &MAY; ignore the Range header. However, HTTP/1.1 origin
819   servers and intermediate caches ought to support byte ranges when
820   possible, since Range supports efficient recovery from partially
821   failed transfers, and supports efficient partial retrieval of large
822   representations.
823</t>
824<t>
825   If the server supports the Range header and the specified range or
826   ranges are appropriate for the representation:
827  <list style="symbols">
828     <t>The presence of a Range header in an unconditional GET modifies
829        what is returned if the GET is otherwise successful. In other
830        words, the response carries a status code of 206 (Partial
831        Content) instead of 200 (OK).</t>
832
833     <t>The presence of a Range header in a conditional GET (a request
834        using one or both of If-Modified-Since and If-None-Match, or
835        one or both of If-Unmodified-Since and If-Match) modifies what
836        is returned if the GET is otherwise successful and the
837        condition is true. It does not affect the 304 (Not Modified)
838        response returned if the conditional is false.</t>
839  </list>
840</t>
841<t>
842   In some cases, it might be more appropriate to use the If-Range
843   header (see <xref target="header.if-range"/>) in addition to the Range header.
844</t>
845<t>
846   If a proxy that supports ranges receives a Range request, forwards
847   the request to an inbound server, and receives an entire representation in
848   reply, it &SHOULD; only return the requested range to its client. It
849   &SHOULD; store the entire received response in its cache if that is
850   consistent with its cache allocation policies.
851</t>
852</section>
853</section>
854</section>
855
856<section title="IANA Considerations" anchor="IANA.considerations">
857
858<section title="Status Code Registration" anchor="status.code.registration">
859<t>
860   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
861   should be updated with the registrations below:
862</t>
863<?BEGININC p5-range.iana-status-codes ?>
864<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
865<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
866   <ttcol>Value</ttcol>
867   <ttcol>Description</ttcol>
868   <ttcol>Reference</ttcol>
869   <c>206</c>
870   <c>Partial Content</c>
871   <c>
872      <xref target="status.206"/>
873   </c>
874   <c>416</c>
875   <c>Requested Range Not Satisfiable</c>
876   <c>
877      <xref target="status.416"/>
878   </c>
879</texttable>
880<!--(END)-->
881<?ENDINC p5-range.iana-status-codes ?>
882</section>
883
884<section title="Header Field Registration" anchor="header.field.registration">
885<t>
886   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> should be updated
887   with the permanent registrations below (see <xref target="RFC3864"/>):
888</t>
889<?BEGININC p5-range.iana-headers ?>
890<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
891<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
892   <ttcol>Header Field Name</ttcol>
893   <ttcol>Protocol</ttcol>
894   <ttcol>Status</ttcol>
895   <ttcol>Reference</ttcol>
896
897   <c>Accept-Ranges</c>
898   <c>http</c>
899   <c>standard</c>
900   <c>
901      <xref target="header.accept-ranges"/>
902   </c>
903   <c>Content-Range</c>
904   <c>http</c>
905   <c>standard</c>
906   <c>
907      <xref target="header.content-range"/>
908   </c>
909   <c>If-Range</c>
910   <c>http</c>
911   <c>standard</c>
912   <c>
913      <xref target="header.if-range"/>
914   </c>
915   <c>Range</c>
916   <c>http</c>
917   <c>standard</c>
918   <c>
919      <xref target="header.range"/>
920   </c>
921</texttable>
922<!--(END)-->
923<?ENDINC p5-range.iana-headers ?>
924<t>
925   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
926</t>
927</section>
928</section>
929
930<section title="Security Considerations" anchor="security.considerations">
931<t>
932   No additional security considerations have been identified beyond
933   those applicable to HTTP in general &messaging;.
934</t>
935</section>
936
937<section title="Acknowledgments" anchor="ack">
938<t>
939   Most of the specification of ranges is based on work originally done
940   by Ari Luotonen and John Franks, with additional input from Steve
941   Zilles, Daniel W. Connolly, Roy T. Fielding, Jim Gettys, Martin Hamilton,
942   Koen Holtman, Shel Kaplan, Paul Leach, Alex Lopez-Ortiz, Larry Masinter,
943   Jeff Mogul, Lou Montulli, David W. Morris, Luigi Rizzo, and Bill Weihl.
944</t>
945</section>
946</middle>
947<back>
948
949<references title="Normative References">
950
951<reference anchor="Part1">
952  <front>
953    <title abbrev="HTTP/1.1">HTTP/1.1, part 1: URIs, Connections, and Message Parsing</title>
954    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
955      <organization abbrev="Day Software">Day Software</organization>
956      <address><email>fielding@gbiv.com</email></address>
957    </author>
958    <author initials="J." surname="Gettys" fullname="Jim Gettys">
959      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
960      <address><email>jg@freedesktop.org</email></address>
961    </author>
962    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
963      <organization abbrev="HP">Hewlett-Packard Company</organization>
964      <address><email>JeffMogul@acm.org</email></address>
965    </author>
966    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
967      <organization abbrev="Microsoft">Microsoft Corporation</organization>
968      <address><email>henrikn@microsoft.com</email></address>
969    </author>
970    <author initials="L." surname="Masinter" fullname="Larry Masinter">
971      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
972      <address><email>LMM@acm.org</email></address>
973    </author>
974    <author initials="P." surname="Leach" fullname="Paul J. Leach">
975      <organization abbrev="Microsoft">Microsoft Corporation</organization>
976      <address><email>paulle@microsoft.com</email></address>
977    </author>
978    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
979      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
980      <address><email>timbl@w3.org</email></address>
981    </author>
982    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
983      <organization abbrev="W3C">World Wide Web Consortium</organization>
984      <address><email>ylafon@w3.org</email></address>
985    </author>
986    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
987      <organization abbrev="greenbytes">greenbytes GmbH</organization>
988      <address><email>julian.reschke@greenbytes.de</email></address>
989    </author>
990    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
991  </front>
992  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
993  <x:source href="p1-messaging.xml" basename="p1-messaging"/>
994</reference>
995
996<reference anchor="Part4">
997  <front>
998    <title abbrev="HTTP/1.1">HTTP/1.1, part 4: Conditional Requests</title>
999    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
1000      <organization abbrev="Day Software">Day Software</organization>
1001      <address><email>fielding@gbiv.com</email></address>
1002    </author>
1003    <author initials="J." surname="Gettys" fullname="Jim Gettys">
1004      <organization abbrev="Alcatel-Lucent">Alcatel-Lucent Bell Labs</organization>
1005      <address><email>jg@freedesktop.org</email></address>
1006    </author>
1007    <author initials="J." surname="Mogul" fullname="Jeffrey C. Mogul">
1008      <organization abbrev="HP">Hewlett-Packard Company</organization>
1009      <address><email>JeffMogul@acm.org</email></address>
1010    </author>
1011    <author initials="H." surname="Frystyk" fullname="Henrik Frystyk Nielsen">
1012      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1013      <address><email>henrikn@microsoft.com</email></address>
1014    </author>
1015    <author initials="L." surname="Masinter" fullname="Larry Masinter">
1016      <organization abbrev="Adobe Systems">Adobe Systems, Incorporated</organization>
1017      <address><email>LMM@acm.org</email></address>
1018    </author>
1019    <author initials="P." surname="Leach" fullname="Paul J. Leach">
1020      <organization abbrev="Microsoft">Microsoft Corporation</organization>
1021      <address><email>paulle@microsoft.com</email></address>
1022    </author>
1023    <author initials="T." surname="Berners-Lee" fullname="Tim Berners-Lee">
1024      <organization abbrev="W3C/MIT">World Wide Web Consortium</organization>
1025      <address><email>timbl@w3.org</email></address>
1026    </author>
1027    <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
1028      <organization abbrev="W3C">World Wide Web Consortium</organization>
1029      <address><email>ylafon@w3.org</email></address>
1030    </author>
1031    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1032      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1033      <address><email>julian.reschke@greenbytes.de</email></address>
1034    </author>
1035    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1036  </front>
1037  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
1038  <x:source href="p4-conditional.xml" basename="p4-conditional"/>
1039</reference>
1040
1041<reference anchor="RFC2046">
1042  <front>
1043    <title abbrev="Media Types">Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types</title>
1044    <author initials="N." surname="Freed" fullname="Ned Freed">
1045      <organization>Innosoft International, Inc.</organization>
1046      <address><email>ned@innosoft.com</email></address>
1047    </author>
1048    <author initials="N." surname="Borenstein" fullname="Nathaniel S. Borenstein">
1049      <organization>First Virtual Holdings</organization>
1050      <address><email>nsb@nsb.fv.com</email></address>
1051    </author>
1052    <date month="November" year="1996"/>
1053  </front>
1054  <seriesInfo name="RFC" value="2046"/>
1055</reference>
1056
1057<reference anchor="RFC2119">
1058  <front>
1059    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
1060    <author initials="S." surname="Bradner" fullname="Scott Bradner">
1061      <organization>Harvard University</organization>
1062      <address><email>sob@harvard.edu</email></address>
1063    </author>
1064    <date month="March" year="1997"/>
1065  </front>
1066  <seriesInfo name="BCP" value="14"/>
1067  <seriesInfo name="RFC" value="2119"/>
1068</reference>
1069
1070<reference anchor="RFC5234">
1071  <front>
1072    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
1073    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
1074      <organization>Brandenburg InternetWorking</organization>
1075      <address>
1076        <email>dcrocker@bbiw.net</email>
1077      </address> 
1078    </author>
1079    <author initials="P." surname="Overell" fullname="Paul Overell">
1080      <organization>THUS plc.</organization>
1081      <address>
1082        <email>paul.overell@thus.net</email>
1083      </address>
1084    </author>
1085    <date month="January" year="2008"/>
1086  </front>
1087  <seriesInfo name="STD" value="68"/>
1088  <seriesInfo name="RFC" value="5234"/>
1089</reference>
1090
1091</references>
1092
1093<references title="Informative References">
1094
1095<reference anchor="RFC2616">
1096  <front>
1097    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
1098    <author initials="R." surname="Fielding" fullname="R. Fielding">
1099      <organization>University of California, Irvine</organization>
1100      <address><email>fielding@ics.uci.edu</email></address>
1101    </author>
1102    <author initials="J." surname="Gettys" fullname="J. Gettys">
1103      <organization>W3C</organization>
1104      <address><email>jg@w3.org</email></address>
1105    </author>
1106    <author initials="J." surname="Mogul" fullname="J. Mogul">
1107      <organization>Compaq Computer Corporation</organization>
1108      <address><email>mogul@wrl.dec.com</email></address>
1109    </author>
1110    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
1111      <organization>MIT Laboratory for Computer Science</organization>
1112      <address><email>frystyk@w3.org</email></address>
1113    </author>
1114    <author initials="L." surname="Masinter" fullname="L. Masinter">
1115      <organization>Xerox Corporation</organization>
1116      <address><email>masinter@parc.xerox.com</email></address>
1117    </author>
1118    <author initials="P." surname="Leach" fullname="P. Leach">
1119      <organization>Microsoft Corporation</organization>
1120      <address><email>paulle@microsoft.com</email></address>
1121    </author>
1122    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
1123      <organization>W3C</organization>
1124      <address><email>timbl@w3.org</email></address>
1125    </author>
1126    <date month="June" year="1999"/>
1127  </front>
1128  <seriesInfo name="RFC" value="2616"/>
1129</reference>
1130
1131<reference anchor='RFC3864'>
1132  <front>
1133    <title>Registration Procedures for Message Header Fields</title>
1134    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
1135      <organization>Nine by Nine</organization>
1136      <address><email>GK-IETF@ninebynine.org</email></address>
1137    </author>
1138    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
1139      <organization>BEA Systems</organization>
1140      <address><email>mnot@pobox.com</email></address>
1141    </author>
1142    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
1143      <organization>HP Labs</organization>
1144      <address><email>JeffMogul@acm.org</email></address>
1145    </author>
1146    <date year='2004' month='September' />
1147  </front>
1148  <seriesInfo name='BCP' value='90' />
1149  <seriesInfo name='RFC' value='3864' />
1150</reference>
1151
1152<reference anchor="RFC4288">
1153  <front>
1154    <title>Media Type Specifications and Registration Procedures</title>
1155    <author initials="N." surname="Freed" fullname="N. Freed">
1156      <organization>Sun Microsystems</organization>
1157      <address>
1158        <email>ned.freed@mrochek.com</email>
1159      </address>
1160    </author>
1161    <author initials="J." surname="Klensin" fullname="J. Klensin">
1162      <address>
1163        <email>klensin+ietf@jck.com</email>
1164      </address>
1165    </author>
1166    <date year="2005" month="December"/>
1167  </front>
1168  <seriesInfo name="BCP" value="13"/>
1169  <seriesInfo name="RFC" value="4288"/>
1170</reference>
1171
1172</references>
1173
1174<section title="Internet Media Type multipart/byteranges" anchor="internet.media.type.multipart.byteranges">
1175<iref item="Media Type" subitem="multipart/byteranges" primary="true"/>
1176<iref item="multipart/byteranges Media Type" primary="true"/>
1177<t>
1178   When an HTTP 206 (Partial Content) response message includes the
1179   content of multiple ranges (a response to a request for multiple
1180   non-overlapping ranges), these are transmitted as a multipart
1181   message-body (<xref target="RFC2046" x:fmt="," x:sec="5.1"/>). The media type for this purpose is called
1182   "multipart/byteranges".  The following is to be registered with IANA <xref target="RFC4288"/>.
1183</t>
1184<x:note>
1185  <t>
1186    <x:h>Note:</x:h> Despite the name "multipart/byteranges" is not limited to the byte ranges only.
1187  </t>
1188</x:note>
1189<t>
1190   The multipart/byteranges media type includes one or more parts, each
1191   with its own Content-Type and Content-Range fields. The required
1192   boundary parameter specifies the boundary string used to separate
1193   each body-part.
1194</t>
1195<t>
1196  <list style="hanging" x:indent="12em">
1197    <t hangText="Type name:">
1198      multipart
1199    </t>
1200    <t hangText="Subtype name:">
1201      byteranges
1202    </t>
1203    <t hangText="Required parameters:">
1204      boundary
1205    </t>
1206    <t hangText="Optional parameters:">
1207      none
1208    </t>
1209    <t hangText="Encoding considerations:">
1210      only "7bit", "8bit", or "binary" are permitted
1211    </t>
1212    <t hangText="Security considerations:">
1213      none
1214    </t>
1215    <t hangText="Interoperability considerations:">
1216      none
1217    </t>
1218    <t hangText="Published specification:">
1219      This specification (see <xref target="internet.media.type.multipart.byteranges"/>).
1220    </t>
1221    <t hangText="Applications that use this media type:">
1222    </t>
1223    <t hangText="Additional information:">
1224      <list style="hanging">
1225        <t hangText="Magic number(s):">none</t>
1226        <t hangText="File extension(s):">none</t>
1227        <t hangText="Macintosh file type code(s):">none</t>
1228      </list>
1229    </t>
1230    <t hangText="Person and email address to contact for further information:">
1231      See Authors Section.
1232    </t>
1233    <t hangText="Intended usage:">
1234      COMMON
1235    </t>
1236    <t hangText="Restrictions on usage:">
1237      none
1238    </t>
1239    <t hangText="Author/Change controller:">
1240      IESG
1241    </t>
1242  </list>
1243</t>
1244<figure><preamble>
1245   For example:
1246</preamble><artwork type="example">
1247  HTTP/1.1 206 Partial Content
1248  Date: Wed, 15 Nov 1995 06:25:24 GMT
1249  Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
1250  Content-type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
1251 
1252  --THIS_STRING_SEPARATES
1253  Content-type: application/pdf
1254  Content-range: bytes 500-999/8000
1255 
1256  ...the first range...
1257  --THIS_STRING_SEPARATES
1258  Content-type: application/pdf
1259  Content-range: bytes 7000-7999/8000
1260 
1261  ...the second range
1262  --THIS_STRING_SEPARATES--
1263</artwork></figure>
1264<figure><preamble>
1265   Other example:
1266</preamble>
1267<artwork type="example">
1268  HTTP/1.1 206 Partial Content
1269  Date: Tue, 14 Nov 1995 06:25:24 GMT
1270  Last-Modified: Tue, 14 July 04:58:08 GMT
1271  Content-type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
1272 
1273  --THIS_STRING_SEPARATES
1274  Content-type: video/example
1275  Content-range: exampleunit 1.2-4.3/25
1276 
1277  ...the first range...
1278  --THIS_STRING_SEPARATES
1279  Content-type: video/example
1280  Content-range: exampleunit 11.2-14.3/25
1281 
1282  ...the second range
1283  --THIS_STRING_SEPARATES--
1284</artwork>
1285</figure>
1286<t>
1287      Notes:
1288  <list style="numbers">
1289      <t>Additional CRLFs &MAY; precede the first boundary string in the body.</t>
1290
1291      <t>Although <xref target="RFC2046"/> permits the boundary string to be
1292         quoted, some existing implementations handle a quoted boundary
1293         string incorrectly.</t>
1294
1295      <t>A number of browsers and servers were coded to an early draft
1296         of the byteranges specification to use a media type of
1297         multipart/x-byteranges<iref item="multipart/x-byteranges Media Type"/><iref item="Media Type" subitem="multipart/x-byteranges"/>, which is almost, but not quite
1298         compatible with the version documented in HTTP/1.1.</t>
1299  </list>
1300</t>
1301</section>
1302
1303<section title="Compatibility with Previous Versions" anchor="compatibility">
1304<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
1305<t>
1306  Clarify that it is not ok to use a weak cache validator in a 206 response.
1307  (<xref target="status.206"/>)
1308</t>
1309<t>
1310  Clarify that multipart/byteranges can consist of a single part.
1311  (<xref target="internet.media.type.multipart.byteranges"/>)
1312</t>
1313
1314</section>
1315
1316</section>
1317
1318<?BEGININC p5-range.abnf-appendix ?>
1319<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
1320<figure>
1321<artwork type="abnf" name="p5-range.parsed-abnf">
1322<x:ref>Accept-Ranges</x:ref> = "Accept-Ranges:" OWS Accept-Ranges-v
1323<x:ref>Accept-Ranges-v</x:ref> = acceptable-ranges
1324
1325<x:ref>Content-Range</x:ref> = "Content-Range:" OWS Content-Range-v
1326<x:ref>Content-Range-v</x:ref> = content-range-spec
1327
1328<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part1], Section 6.1&gt;
1329
1330<x:ref>If-Range</x:ref> = "If-Range:" OWS If-Range-v
1331<x:ref>If-Range-v</x:ref> = entity-tag / HTTP-date
1332
1333<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 1.2.2&gt;
1334
1335<x:ref>Range</x:ref> = "Range:" OWS Range-v
1336<x:ref>Range-v</x:ref> = byte-ranges-specifier / other-ranges-specifier
1337
1338<x:ref>acceptable-ranges</x:ref> = ( *( "," OWS ) range-unit *( OWS "," [ OWS
1339 range-unit ] ) ) / "none"
1340
1341<x:ref>byte-content-range-spec</x:ref> = bytes-unit SP byte-range-resp-spec "/" (
1342 instance-length / "*" )
1343<x:ref>byte-range-resp-spec</x:ref> = ( first-byte-pos "-" last-byte-pos ) / "*"
1344<x:ref>byte-range-set</x:ref> = ( *( "," OWS ) byte-range-spec ) / (
1345 suffix-byte-range-spec *( OWS "," [ ( OWS byte-range-spec ) /
1346 suffix-byte-range-spec ] ) )
1347<x:ref>byte-range-spec</x:ref> = first-byte-pos "-" [ last-byte-pos ]
1348<x:ref>byte-ranges-specifier</x:ref> = bytes-unit "=" byte-range-set
1349<x:ref>bytes-unit</x:ref> = "bytes"
1350
1351<x:ref>content-range-spec</x:ref> = byte-content-range-spec /
1352 other-content-range-spec
1353
1354<x:ref>entity-tag</x:ref> = &lt;entity-tag, defined in [Part4], Section 2&gt;
1355
1356<x:ref>first-byte-pos</x:ref> = 1*DIGIT
1357
1358<x:ref>instance-length</x:ref> = 1*DIGIT
1359
1360<x:ref>last-byte-pos</x:ref> = 1*DIGIT
1361
1362<x:ref>other-content-range-spec</x:ref> = other-range-unit SP other-range-resp-spec
1363<x:ref>other-range-resp-spec</x:ref> = *CHAR
1364<x:ref>other-range-set</x:ref> = 1*CHAR
1365<x:ref>other-range-unit</x:ref> = token
1366<x:ref>other-ranges-specifier</x:ref> = other-range-unit "=" other-range-set
1367
1368<x:ref>range-unit</x:ref> = bytes-unit / other-range-unit
1369
1370<x:ref>suffix-byte-range-spec</x:ref> = "-" suffix-length
1371<x:ref>suffix-length</x:ref> = 1*DIGIT
1372
1373<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 1.2.2&gt;
1374</artwork>
1375</figure>
1376<figure><preamble>ABNF diagnostics:</preamble><artwork type="inline">
1377; Accept-Ranges defined but not used
1378; Content-Range defined but not used
1379; If-Range defined but not used
1380; Range defined but not used
1381</artwork></figure></section>
1382<?ENDINC p5-range.abnf-appendix ?>
1383
1384
1385<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
1386
1387<section title="Since RFC2616">
1388<t>
1389  Extracted relevant partitions from <xref target="RFC2616"/>.
1390</t>
1391</section>
1392
1393<section title="Since draft-ietf-httpbis-p5-range-00">
1394<t>
1395  Closed issues:
1396  <list style="symbols"> 
1397    <t>
1398      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/18"/>:
1399      "Cache validators in 206 responses"
1400      (<eref target="http://purl.org/NET/http-errata#ifrange206"/>)
1401    </t>
1402    <t>
1403      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/35"/>:
1404      "Normative and Informative references"
1405    </t>
1406    <t>
1407      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/86"/>:
1408      "Normative up-to-date references"
1409    </t>
1410  </list>
1411</t>
1412</section>
1413
1414<section title="Since draft-ietf-httpbis-p5-range-01">
1415<t>
1416  Closed issues:
1417  <list style="symbols"> 
1418    <t>
1419      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/55"/>:
1420      "Updating to RFC4288"
1421    </t>
1422  </list>
1423</t>
1424<t>
1425  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
1426  <list style="symbols"> 
1427    <t>
1428      Add explicit references to BNF syntax and rules imported from other parts of the specification.
1429    </t>
1430  </list>
1431</t>
1432</section>
1433
1434<section title="Since draft-ietf-httpbis-p5-range-02" anchor="changes.since.02">
1435<t>
1436  Ongoing work on IANA Message Header Registration (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/40"/>):
1437  <list style="symbols"> 
1438    <t>
1439      Reference RFC 3984, and update header registrations for headers defined
1440      in this document.
1441    </t>
1442  </list>
1443</t>
1444</section>
1445
1446<section title="Since draft-ietf-httpbis-p5-range-03" anchor="changes.since.03">
1447<t>
1448</t>
1449</section>
1450
1451<section title="Since draft-ietf-httpbis-p5-range-04" anchor="changes.since.04">
1452<t>
1453  Closed issues:
1454  <list style="symbols"> 
1455    <t>
1456      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/133"/>:
1457      "multipart/byteranges minimum number of parts"
1458    </t>
1459  </list>
1460</t>
1461<t>
1462  Ongoing work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
1463  <list style="symbols"> 
1464    <t>
1465      Use "/" instead of "|" for alternatives.
1466    </t>
1467    <t>
1468      Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
1469      whitespace ("OWS") and required whitespace ("RWS").
1470    </t>
1471    <t>
1472      Rewrite ABNFs to spell out whitespace rules, factor out
1473      header value format definitions.
1474    </t>
1475  </list>
1476</t>
1477</section>
1478
1479<section title="Since draft-ietf-httpbis-p5-range-05" anchor="changes.since.05">
1480<t>
1481  Closed issues:
1482  <list style="symbols"> 
1483    <t>
1484      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/142"/>:
1485      "State base for *-byte-pos and suffix-length"
1486    </t>
1487  </list>
1488</t>
1489<t>
1490  Ongoing work on Custom Ranges (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/85"/>):
1491  <list style="symbols"> 
1492    <t>
1493      Remove bias in favor of byte ranges; allow custom ranges in ABNF.
1494    </t>
1495  </list>
1496</t>
1497<t>
1498  Final work on ABNF conversion (<eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/36"/>):
1499  <list style="symbols"> 
1500    <t>
1501      Add appendix containing collected and expanded ABNF, reorganize ABNF introduction.
1502    </t>
1503  </list>
1504</t>
1505</section>
1506
1507<section title="Since draft-ietf-httpbis-p5-range-06" anchor="changes.since.06">
1508<t>
1509  Closed issues:
1510  <list style="symbols"> 
1511    <t>
1512      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/161"/>:
1513      "base for numeric protocol elements"
1514    </t>
1515  </list>
1516</t>
1517</section>
1518
1519<section title="Since draft-ietf-httpbis-p5-range-07" anchor="changes.since.07">
1520<t>
1521  Closed issues:
1522  <list style="symbols">
1523    <t>
1524      Fixed discrepancy in the If-Range definition about allowed validators.
1525    </t>
1526    <t>
1527      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/150" />: "multipart/byteranges for custom range units"
1528    </t>
1529    <t>
1530      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/151" />: "range unit missing from other-ranges-specifier in Range header"
1531    </t>
1532    <t>
1533      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/198"/>:
1534      "move IANA registrations for optional status codes"
1535    </t>
1536  </list>
1537</t>
1538</section>
1539
1540<section title="Since draft-ietf-httpbis-p5-range-08" anchor="changes.since.08">
1541<t>
1542  No significant changes.
1543</t>
1544</section>
1545
1546<section title="Since draft-ietf-httpbis-p5-range-09" anchor="changes.since.09">
1547<t>
1548 No significant changes.
1549</t>
1550</section>
1551
1552<section title="Since draft-ietf-httpbis-p5-range-10" anchor="changes.since.10">
1553<t>
1554  Closed issues:
1555  <list style="symbols"> 
1556    <t>
1557      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/69"/>:
1558      "Clarify 'Requested Variant'"
1559    </t>
1560    <t>
1561      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/109"/>:
1562      "Clarify entity / representation / variant terminology"
1563    </t>
1564    <t>
1565      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>:
1566      "Clarify entity / representation / variant terminology"
1567    </t>
1568    <t>
1569      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/220"/>:
1570      "consider removing the 'changes from 2068' sections"
1571    </t>
1572  </list>
1573</t>
1574</section>
1575
1576</section>
1577
1578</back>
1579</rfc>
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