source: draft-ietf-httpbis/latest/p5-range.xml @ 2143

Last change on this file since 2143 was 2143, checked in by fielding@…, 8 years ago

(editorial) move status codes to where they are used; no text changes

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  • Property svn:mime-type set to text/xml
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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 "January">
16  <!ENTITY ID-YEAR "2013">
17  <!ENTITY Note "<x:h xmlns:x='http://purl.org/net/xml2rfc/ext'>Note:</x:h>">
18  <!ENTITY architecture               "<xref target='Part1' x:rel='#architecture' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
19  <!ENTITY conformance                "<xref target='Part1' x:rel='#conformance' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
20  <!ENTITY notation                   "<xref target='Part1' x:rel='#notation' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
21  <!ENTITY abnf-extension             "<xref target='Part1' x:rel='#abnf.extension' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
22  <!ENTITY acks                       "<xref target='Part1' x:rel='#acks' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
23  <!ENTITY whitespace                 "<xref target='Part1' x:rel='#whitespace' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
24  <!ENTITY field-components           "<xref target='Part1' x:rel='#field.components' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
25  <!ENTITY http-date                  "<xref target='Part2' x:rel='#http.date' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
26  <!ENTITY messaging                  "<xref target='Part1' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
27  <!ENTITY semantics                  "<xref target='Part2' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
28  <!ENTITY entity-tags                "<xref target='Part4' x:rel='#header.etag' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
29  <!ENTITY weak-and-strong-validators "<xref target='Part4' x:rel='#weak.and.strong.validators' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
30  <!ENTITY lastmod-comparison         "<xref target='Part4' x:rel='#lastmod.comparison' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
31  <!ENTITY p6-heuristic               "<xref target='Part6' x:rel='#heuristic.freshness' xmlns:x='http://purl.org/net/xml2rfc/ext'/>">
32]>
33<?rfc toc="yes" ?>
34<?rfc symrefs="yes" ?>
35<?rfc sortrefs="yes" ?>
36<?rfc compact="yes"?>
37<?rfc subcompact="no" ?>
38<?rfc linkmailto="no" ?>
39<?rfc editing="no" ?>
40<?rfc comments="yes"?>
41<?rfc inline="yes"?>
42<?rfc rfcedstyle="yes"?>
43<?rfc-ext allow-markup-in-artwork="yes" ?>
44<?rfc-ext include-references-in-index="yes" ?>
45<rfc obsoletes="2616" category="std" x:maturity-level="proposed"
46     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p5-range-&ID-VERSION;"
47     xmlns:x='http://purl.org/net/xml2rfc/ext'>
48<x:link rel="prev" basename="p4-conditional"/>
49<x:link rel="next" basename="p6-cache"/>
50<x:feedback template="mailto:ietf-http-wg@w3.org?subject={docname},%20%22{section}%22&amp;body=&lt;{ref}&gt;:"/>
51<front>
52
53  <title abbrev="HTTP/1.1 Range Requests">Hypertext Transfer Protocol (HTTP/1.1): Range Requests</title>
54
55  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
56    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
57    <address>
58      <postal>
59        <street>345 Park Ave</street>
60        <city>San Jose</city>
61        <region>CA</region>
62        <code>95110</code>
63        <country>USA</country>
64      </postal>
65      <email>fielding@gbiv.com</email>
66      <uri>http://roy.gbiv.com/</uri>
67    </address>
68  </author>
69
70  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
71    <organization abbrev="W3C">World Wide Web Consortium</organization>
72    <address>
73      <postal>
74        <street>W3C / ERCIM</street>
75        <street>2004, rte des Lucioles</street>
76        <city>Sophia-Antipolis</city>
77        <region>AM</region>
78        <code>06902</code>
79        <country>France</country>
80      </postal>
81      <email>ylafon@w3.org</email>
82      <uri>http://www.raubacapeu.net/people/yves/</uri>
83    </address>
84  </author>
85
86  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
87    <organization abbrev="greenbytes">greenbytes GmbH</organization>
88    <address>
89      <postal>
90        <street>Hafenweg 16</street>
91        <city>Muenster</city><region>NW</region><code>48155</code>
92        <country>Germany</country>
93      </postal>
94      <email>julian.reschke@greenbytes.de</email>
95      <uri>http://greenbytes.de/tech/webdav/</uri>
96    </address>
97  </author>
98
99  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
100  <workgroup>HTTPbis Working Group</workgroup>
101
102<abstract>
103<t>
104   The Hypertext Transfer Protocol (HTTP) is an application-level protocol for
105   distributed, collaborative, hypertext information systems. This document
106   defines range requests and the rules for constructing and combining
107   responses to those requests.
108</t>
109</abstract>
110
111<note title="Editorial Note (To be removed by RFC Editor)">
112  <t>
113    Discussion of this draft takes place on the HTTPBIS working group
114    mailing list (ietf-http-wg@w3.org), which is archived at
115    <eref target="http://lists.w3.org/Archives/Public/ietf-http-wg/"/>.
116  </t>
117  <t>
118    The current issues list is at
119    <eref target="http://tools.ietf.org/wg/httpbis/trac/report/3"/> and related
120    documents (including fancy diffs) can be found at
121    <eref target="http://tools.ietf.org/wg/httpbis/"/>.
122  </t>
123  <t>
124    The changes in this draft are summarized in <xref target="changes.since.21"/>.
125  </t>
126</note>
127</front>
128<middle>
129<section title="Introduction" anchor="introduction">
130<t>
131   HTTP clients often encounter interrupted data transfers as a result
132   of canceled requests or dropped connections.  When a client has stored
133   a partial representation, it is desirable to request the remainder
134   of that representation in a subsequent request rather than transfer
135   the entire representation.
136   There are also a number of Web applications that benefit from being
137   able to request only a subset of a larger representation, such as a
138   single page of a very large document or only part of an image to be
139   rendered by a device with limited local storage.
140</t>
141<t>
142   This document defines HTTP/1.1 range requests,
143   partial responses, and the multipart/byteranges media type.
144   The protocol for range requests is an &OPTIONAL; feature of HTTP,
145   designed so resources or recipients that do not implement this feature
146   can respond as if it is a normal GET request without impacting
147   interoperability.  Partial responses are indicated by a distinct status
148   code to not be mistaken for full responses by intermediate caches
149   that might not implement the feature.
150</t>
151<t>
152   Although the HTTP range request mechanism is designed to allow for
153   extensible range types, this specification only defines requests for
154   byte ranges.
155</t>
156
157<section title="Conformance and Error Handling" anchor="conformance">
158<t>
159   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
160   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
161   document are to be interpreted as described in <xref target="RFC2119"/>.
162</t>
163<t>
164   Conformance criteria and considerations regarding error handling
165   are defined in &conformance;.
166</t>
167</section>
168
169<section title="Syntax Notation" anchor="notation">
170<t>
171   This specification uses the Augmented Backus-Naur Form (ABNF) notation
172   of <xref target="RFC5234"/> with the list rule extension defined in
173   &notation;. <xref target="imported.abnf"/> describes rules imported from
174   other documents. <xref target="collected.abnf"/> shows the collected ABNF
175   with the list rule expanded.
176</t>
177</section>
178</section>
179
180
181<section title="Range Units" anchor="range.units">
182  <x:anchor-alias value="bytes-unit"/>
183  <x:anchor-alias value="other-range-unit"/>
184  <x:anchor-alias value="range-unit"/>
185  <x:anchor-alias value="range unit"/>
186<t>
187   A representation can be partitioned into subranges according to various
188   structural units, depending on the structure inherent in the
189   representation's media type. Such a <x:dfn>range unit</x:dfn> can be used
190   in the <x:ref>Range</x:ref> (<xref target="header.range"/>) and
191   <x:ref>Content-Range</x:ref> (<xref target="header.content-range"/>)
192   header fields to delineate the parts of a representation that are
193   either requested or transferred, respectively.
194</t>
195<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"/>
196  <x:ref>range-unit</x:ref>       = <x:ref>bytes-unit</x:ref> / <x:ref>other-range-unit</x:ref>
197  <x:ref>bytes-unit</x:ref>       = "bytes"
198  <x:ref>other-range-unit</x:ref> = <x:ref>token</x:ref>
199</artwork></figure>
200
201<section title="Byte Ranges" anchor="byte.ranges">
202<t>
203   Since all HTTP representations are transferred as sequences
204   of bytes, the concept of a byte range is meaningful for any HTTP
205   representation. (However, not all clients and servers need to support byte-range
206   operations.)
207</t>
208<t>
209   Byte range specifications in HTTP apply to the sequence of bytes in
210   the representation data (not necessarily the same as the message body).
211</t>
212<t anchor="rule.ranges-specifier">
213  <x:anchor-alias value="byte-range-set"/>
214  <x:anchor-alias value="byte-range-spec"/>
215  <x:anchor-alias value="byte-ranges-specifier"/>
216  <x:anchor-alias value="first-byte-pos"/>
217  <x:anchor-alias value="last-byte-pos"/>
218  <x:anchor-alias value="ranges-specifier"/>
219  <x:anchor-alias value="suffix-byte-range-spec"/>
220  <x:anchor-alias value="suffix-length"/>
221   A byte range operation &MAY; specify a single range of bytes, or a set
222   of ranges within a single representation.
223</t>
224<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"/>
225  <x:ref>byte-ranges-specifier</x:ref> = <x:ref>bytes-unit</x:ref> "=" <x:ref>byte-range-set</x:ref>
226  <x:ref>byte-range-set</x:ref>  = 1#( <x:ref>byte-range-spec</x:ref> / <x:ref>suffix-byte-range-spec</x:ref> )
227  <x:ref>byte-range-spec</x:ref> = <x:ref>first-byte-pos</x:ref> "-" [ <x:ref>last-byte-pos</x:ref> ]
228  <x:ref>first-byte-pos</x:ref>  = 1*<x:ref>DIGIT</x:ref>
229  <x:ref>last-byte-pos</x:ref>   = 1*<x:ref>DIGIT</x:ref>
230</artwork></figure>
231<t>
232   The first-byte-pos value in a byte-range-spec gives the byte-offset
233   of the first byte in a range. The last-byte-pos value gives the
234   byte-offset of the last byte in the range; that is, the byte
235   positions specified are inclusive. Byte offsets start at zero.
236</t>
237<t>
238   If the last-byte-pos value is present, it &MUST; be greater than or
239   equal to the first-byte-pos in that byte-range-spec, or the byte-range-spec
240   is syntactically invalid. The recipient of a byte-range-set
241   that includes one or more syntactically invalid byte-range-spec
242   values &MUST; ignore the header field that includes that byte-range-set.
243</t>
244<t>
245   If the last-byte-pos value is absent, or if the value is greater than
246   or equal to the current length of the representation data, last-byte-pos is
247   taken to be equal to one less than the current length of the representation
248   in bytes.
249</t>
250<t>
251   By its choice of last-byte-pos, a client can limit the number of
252   bytes retrieved without knowing the size of the representation.
253</t>
254<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="suffix-byte-range-spec"/><iref primary="true" item="Grammar" subitem="suffix-length"/>
255  <x:ref>suffix-byte-range-spec</x:ref> = "-" <x:ref>suffix-length</x:ref>
256  <x:ref>suffix-length</x:ref> = 1*<x:ref>DIGIT</x:ref>
257</artwork></figure>
258<t>
259   A suffix-byte-range-spec is used to specify the suffix of the
260   representation data, of a length given by the suffix-length value. (That is,
261   this form specifies the last N bytes of a representation.) If the
262   representation is shorter than the specified suffix-length, the entire
263   representation is used.
264</t>
265<t>
266   If a syntactically valid byte-range-set includes at least one byte-range-spec
267   whose first-byte-pos is less than the current length of
268   the representation, or at least one suffix-byte-range-spec with a non-zero
269   suffix-length, then the byte-range-set is satisfiable.
270   Otherwise, the byte-range-set is unsatisfiable. If the byte-range-set
271   is unsatisfiable, the server &SHOULD; send a response with a
272   <x:ref>416 (Range Not Satisfiable)</x:ref> status code. Otherwise, the server
273   &SHOULD; send a response with a <x:ref>206 (Partial Content)</x:ref> status code
274   containing the satisfiable ranges of the representation.
275</t>
276<t>
277   In the byte range syntax, <x:ref>first-byte-pos</x:ref>,
278   <x:ref>last-byte-pos</x:ref>, and <x:ref>suffix-length</x:ref> are
279   expressed as decimal number of octets.  Since there is no predefined limit
280   to the length of an HTTP payload, recipients &SHOULD; anticipate
281   potentially large decimal numerals and prevent parsing errors due to integer
282   conversion overflows.
283</t>
284<t>
285   Examples of byte-ranges-specifier values (assuming a representation of
286   length 10000):
287  <list style="symbols">
288     <t>The first 500 bytes (byte offsets 0-499, inclusive):
289<figure><artwork type="example" x:indent-with="   ">
290  bytes=0-499
291</artwork></figure>
292    </t>
293     <t>The second 500 bytes (byte offsets 500-999, inclusive):
294<figure><artwork type="example" x:indent-with="   ">
295  bytes=500-999
296</artwork></figure>
297    </t>
298     <t>The final 500 bytes (byte offsets 9500-9999, inclusive):
299<figure><artwork type="example" x:indent-with="   ">
300  bytes=-500
301</artwork></figure>
302    Or:
303<figure><artwork type="example" x:indent-with="   ">
304  bytes=9500-
305</artwork></figure>
306    </t>
307     <t>The first and last bytes only (bytes 0 and 9999):
308<figure><artwork type="example" x:indent-with="   ">
309  bytes=0-0,-1
310</artwork></figure>
311     </t>
312     <t>Several legal but not canonical specifications of the second 500
313        bytes (byte offsets 500-999, inclusive):
314<figure><artwork type="example" x:indent-with="   ">
315  bytes=500-600,601-999
316  bytes=500-700,601-999
317</artwork></figure>
318     </t>
319  </list>
320</t>
321</section>
322
323<section title="Other Range Units" anchor="range.units.other">
324<t>
325  The only range unit defined by HTTP/1.1 is "bytes"
326  (<xref target="byte.ranges"/>). Additional units can be defined as described
327  in <xref target="range.unit.registry"/>.
328</t>
329</section>
330<section title="Accept-Ranges" anchor="header.accept-ranges">
331  <iref primary="true" item="Accept-Ranges header field" x:for-anchor=""/>
332  <x:anchor-alias value="Accept-Ranges"/>
333  <x:anchor-alias value="acceptable-ranges"/>
334<t>
335   The "Accept-Ranges" header field allows a resource to indicate
336   its acceptance of range requests.
337</t>
338<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Ranges"/><iref primary="true" item="Grammar" subitem="acceptable-ranges"/>
339  <x:ref>Accept-Ranges</x:ref>     = <x:ref>acceptable-ranges</x:ref>
340  <x:ref>acceptable-ranges</x:ref> = 1#<x:ref>range-unit</x:ref> / "none"
341</artwork></figure>
342<t>
343   Origin servers that accept byte-range requests &MAY; send
344</t>
345<figure><artwork type="example">
346  Accept-Ranges: bytes
347</artwork></figure>
348<t>
349   but are not required to do so. Clients &MAY; generate range
350   requests without having received this header field for the resource
351   involved. Range units are defined in <xref target="range.units"/>.
352</t>
353<t>
354   Servers that do not accept any kind of range request for a
355   resource &MAY; send
356</t>
357<figure><artwork type="example">
358  Accept-Ranges: none
359</artwork></figure>
360<t>
361   to advise the client not to attempt a range request.
362</t>
363</section>
364</section>
365
366
367<section title="Range Requests" anchor="range.requests">
368<section title="Range" anchor="header.range">
369  <iref primary="true" item="Range header field" x:for-anchor=""/>
370  <x:anchor-alias value="Range"/>
371  <x:anchor-alias value="other-ranges-specifier"/>
372  <x:anchor-alias value="other-range-set"/>
373<t>
374   The "Range" header field on a GET request modifies the method semantics to
375   request transfer of only one or more sub-ranges of the selected
376   representation data in a successful response, rather than the entire
377   representation data.
378</t>
379<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Range"/>
380  <x:ref>Range</x:ref> = <x:ref>byte-ranges-specifier</x:ref> / <x:ref>other-ranges-specifier</x:ref>
381  <x:ref>other-ranges-specifier</x:ref> = <x:ref>other-range-unit</x:ref> "=" <x:ref>other-range-set</x:ref>
382  <x:ref>other-range-set</x:ref> = 1*<x:ref>CHAR</x:ref>
383</artwork></figure>
384<t>
385   A server &MAY; ignore the Range header field. However, origin servers and
386   intermediate caches ought to support byte ranges when possible, since Range
387   supports efficient recovery from partially failed transfers and partial
388   retrieval of large representations. A server &MUST; ignore a Range header
389   field received with a request method other than GET.
390</t>
391<t>
392   An origin server &MUST; ignore a <x:ref>Range</x:ref> header field that
393   contains a range unit it does not understand. A proxy &MAY; either discard
394   a <x:ref>Range</x:ref> header field that contains a range unit it does not
395   understand or pass it to the next inbound server when forwarding the
396   request.
397</t>
398<t>
399   The Range header field is evaluated after evaluating the preconditions of
400   <xref target="Part4"/> and only if the result of their evaluation is
401   leading toward a <x:ref>200 (OK)</x:ref> response. In other words, Range
402   is ignored when a conditional GET would result in a
403   <x:ref>304 (Not Modified)</x:ref> response.
404</t>
405<t>
406   The If-Range header field (<xref target="header.if-range"/>) can be used as
407   a precondition to applying the Range header field.
408</t>
409<t>
410   If all of the preconditions are true, the server supports the Range header
411   field for the target resource, the specified range(s) are syntactically
412   correct (as defined in <xref target="byte.ranges"/>), and at least one of
413   the ranges has a non-empty intersection with the current selected
414   representation extent, then the server &MAY; respond with a status code of
415   <x:ref>206 (Partial Content)</x:ref> and a payload containing one or more
416   partial representations that correspond to those requested, as defined in
417   <xref target="range.response"/>.
418</t>
419</section>
420
421<section title="If-Range" anchor="header.if-range">
422  <iref primary="true" item="If-Range header field" x:for-anchor=""/>
423  <x:anchor-alias value="If-Range"/>
424<t>
425   If a client has a partial copy of a representation and wishes
426   to have an up-to-date copy of the entire representation, it could use the
427   <x:ref>Range</x:ref> header field with a conditional GET (using
428   either or both of <x:ref>If-Unmodified-Since</x:ref> and
429   <x:ref>If-Match</x:ref>.) However, if the condition fails because the
430   representation has been modified, the client would then have to make a
431   second request to obtain the entire current representation.
432</t>
433<t>
434   The "If-Range" header field allows a client to "short-circuit" the second
435   request. Informally, its meaning is: if the representation is unchanged,
436   send me the part(s) that I am requesting in Range; otherwise, send me the
437   entire representation.
438</t>
439<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="If-Range"/>
440  <x:ref>If-Range</x:ref> = <x:ref>entity-tag</x:ref> / <x:ref>HTTP-date</x:ref>
441</artwork></figure>
442<t>
443   Clients &MUST-NOT; use an entity-tag marked as weak in an If-Range
444   field value and &MUST-NOT; use a <x:ref>Last-Modified</x:ref> date in an
445   If-Range field value unless it has no entity-tag for the representation and
446   the Last-Modified date it does have for the representation is strong
447   in the sense defined by &lastmod-comparison;.
448</t>
449<t>
450   A server that evaluates a conditional range request that is applicable
451   to one of its representations &MUST; evaluate the condition as false if
452   the entity-tag used as a validator is marked as weak or, when an HTTP-date
453   is used as the validator, if the date value is not strong in the sense
454   defined by &lastmod-comparison;. (A server can distinguish between a
455   valid HTTP-date and any form of entity-tag by examining the first
456   two characters.)
457</t>
458<t>
459   The If-Range header field &SHOULD; only be sent by clients together with
460   a Range header field.  The If-Range header field &MUST; be ignored if it
461   is received in a request that does not include a Range header field.
462   The If-Range header field &MUST; be ignored by a server that does not
463   support the sub-range operation.
464</t>
465<t>
466   If the validator given in the If-Range header field matches the current
467   validator for the selected representation of the target resource, then
468   the server &SHOULD; send the specified sub-range of the representation
469   using a <x:ref>206 (Partial Content)</x:ref> response. If the validator
470   does not match, then the server &SHOULD; send the entire representation
471   using a <x:ref>200 (OK)</x:ref> response.
472</t>
473</section>
474</section>
475
476
477<section title="Responses to a Range Request" anchor="range.response">
478<section title="Response to a Single and Multiple Ranges Request">
479<t>
480   When an HTTP message includes the content of a single range (for
481   example, a response to a request for a single range, or to a request
482   for a set of ranges that overlap without any holes), this content is
483   transmitted with a <x:ref>Content-Range</x:ref> header field, and a
484   <x:ref>Content-Length</x:ref> header field showing the number of bytes
485   actually transferred. For example,
486</t>
487<figure><artwork type="message/http; msgtype=&#34;response&#34;" x:indent-with="  ">
488HTTP/1.1 206 Partial Content
489Date: Wed, 15 Nov 1995 06:25:24 GMT
490Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
491Content-Range: bytes 21010-47021/47022
492Content-Length: 26012
493Content-Type: image/gif
494</artwork></figure>
495<t>
496   When an HTTP message includes the content of multiple ranges (for
497   example, a response to a request for multiple non-overlapping
498   ranges), these are transmitted as a multipart message. The multipart
499   media type used for this purpose is "multipart/byteranges" as defined
500   in <xref target="internet.media.type.multipart.byteranges"/>.
501</t>
502<t>
503   A server &MAY; combine requested ranges when those ranges are overlapping
504   (see <xref target="overlapping.ranges"/>).
505</t>
506<t>
507   A response to a request for a single range &MUST-NOT; be sent using the
508   multipart/byteranges media type.  A response to a request for
509   multiple ranges, whose result is a single range, &MAY; be sent as a
510   multipart/byteranges media type with one part. A client that cannot
511   decode a multipart/byteranges message &MUST-NOT; ask for multiple
512   ranges in a single request.
513</t>
514<t>
515   When a client asks for multiple ranges in one request, the
516   server &SHOULD; send them in the order that they appeared in the
517   request.
518</t>
519</section>
520
521<section title="206 Partial Content" anchor="status.206">
522  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
523  <x:anchor-alias value="206"/>
524  <x:anchor-alias value="206 (Partial Content)"/>
525<t>
526   The <x:dfn>206 (Partial Content)</x:dfn> status code indicates that the
527   server has fulfilled the partial GET request for the resource.
528   The request &MUST; have included a <x:ref>Range</x:ref> header field
529   (<xref target="header.range"/>) indicating the desired range, and &MAY; have
530   included an <x:ref>If-Range</x:ref> header field
531   (<xref target="header.if-range"/>) to make the request conditional.
532</t>
533<t>
534   When a 206 response is generated, the sender &MUST; generate the following
535   header fields:
536  <list style="symbols">
537    <t>
538        Either a <x:ref>Content-Range</x:ref> header field
539        (<xref target="header.content-range"/>) indicating
540        the range included with this response, or a multipart/byteranges
541        <x:ref>Content-Type</x:ref> including Content-Range fields for each
542        part. If a <x:ref>Content-Length</x:ref> header field is present in the
543        response, its value &MUST; match the actual number of octets
544        transmitted in the message body.
545    </t>
546    <t>
547        Date
548    </t>
549    <t>
550        <x:ref>Cache-Control</x:ref>, <x:ref>ETag</x:ref>,
551        <x:ref>Expires</x:ref>, <x:ref>Content-Location</x:ref> and/or
552        <x:ref>Vary</x:ref>, if the header field would have been sent in a
553        <x:ref>200 (OK)</x:ref> response to the same request
554    </t>
555  </list>
556</t>
557<t>
558   If a 206 is generated in response to a request with an <x:ref>If-Range</x:ref>
559   header field, the sender &SHOULD-NOT; generate other representation header
560   fields beyond those described above.
561   Otherwise, the sender &MUST; generate all of the same representation header
562   fields that would have been sent in a <x:ref>200 (OK)</x:ref> response
563   to the same request.
564</t>
565<t>
566   Caches &MAY; use a heuristic (see &p6-heuristic;) to determine
567   freshness for 206 responses.
568</t>
569</section>
570
571<section title="416 Range Not Satisfiable" anchor="status.416">
572  <iref primary="true" item="416 Range Not Satisfiable (status code)" x:for-anchor=""/>
573  <x:anchor-alias value="416 (Range Not Satisfiable)"/>
574<t>
575   The <x:dfn>416 (Range Not Satisfiable)</x:dfn> status code
576   indicates that none of the ranges-specifier values in the request's
577   <x:ref>Range</x:ref> header field (<xref target="header.range"/>)
578   overlap the current
579   extent of the selected resource and the request did not include an
580   <x:ref>If-Range</x:ref> header field (<xref target="header.if-range"/>).
581   (For byte-ranges, this means that the first-byte-pos of all of the
582   byte-range-spec values were greater than the current length of the selected
583   representation.)
584</t>
585<t>
586   When this status code is sent in response to a byte-range request, the
587   sender &SHOULD; generate a <x:ref>Content-Range</x:ref> header field
588   specifying the current length of the selected representation
589   (see <xref target="header.content-range"/>).
590</t>
591<figure>
592<preamble>For example:</preamble>
593<artwork type="message/http; msgtype=&#34;response&#34;" x:indent-with="  ">
594HTTP/1.1 416 Range Not Satisfiable
595Date: Mon, 20 Jan 2012 15:41:54 GMT
596Content-Range: bytes */47022
597Content-Type: image/gif
598</artwork></figure>
599<x:note>
600  <t>
601    &Note; Clients cannot depend on servers to send a <x:ref>416 (Range Not
602    Satisfiable)</x:ref> response instead of a <x:ref>200 (OK)</x:ref>
603    response for an unsatisfiable <x:ref>Range</x:ref> header field, since not
604    all servers implement this header field.
605  </t>
606</x:note>
607</section>
608
609<section title="Content-Range" anchor="header.content-range">
610  <iref primary="true" item="Content-Range header field" x:for-anchor=""/>
611  <x:anchor-alias value="Content-Range"/>
612  <x:anchor-alias value="byte-content-range"/>
613  <x:anchor-alias value="byte-range-resp"/>
614  <x:anchor-alias value="byte-range"/>
615  <x:anchor-alias value="unsatisfied-range"/>
616  <x:anchor-alias value="complete-length"/>
617  <x:anchor-alias value="other-content-range"/>
618  <x:anchor-alias value="other-range-resp"/>
619<t>
620   The "Content-Range" header field is sent with a partial representation to
621   specify where in the full representation the payload body is intended to be
622   applied.
623</t>
624<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Content-Range"/><iref primary="true" item="Grammar" subitem="byte-content-range"/><iref primary="true" item="Grammar" subitem="byte-range-resp"/><iref primary="true" item="Grammar" subitem="byte-range"/><iref primary="true" item="Grammar" subitem="unsatisfied-range"/><iref primary="true" item="Grammar" subitem="other-content-range"/><iref primary="true" item="Grammar" subitem="other-range-resp"/><iref primary="true" item="Grammar" subitem="complete-length"/>
625  <x:ref>Content-Range</x:ref>       = <x:ref>byte-content-range</x:ref>
626                      / <x:ref>other-content-range</x:ref>
627                         
628  <x:ref>byte-content-range</x:ref>  = <x:ref>bytes-unit</x:ref> <x:ref>SP</x:ref>
629                        ( <x:ref>byte-range-resp</x:ref> / <x:ref>unsatisfied-range</x:ref> )
630
631  <x:ref>byte-range-resp</x:ref>     = <x:ref>byte-range</x:ref> "/" ( <x:ref>complete-length</x:ref> / "*" )
632  <x:ref>byte-range</x:ref>          = <x:ref>first-byte-pos</x:ref> "-" <x:ref>last-byte-pos</x:ref>
633  <x:ref>unsatisfied-range</x:ref>   = "*/" <x:ref>complete-length</x:ref>
634                         
635  <x:ref>complete-length</x:ref>     = 1*<x:ref>DIGIT</x:ref>
636 
637  <x:ref>other-content-range</x:ref> = <x:ref>other-range-unit</x:ref> <x:ref>SP</x:ref> <x:ref>other-range-resp</x:ref>
638  <x:ref>other-range-resp</x:ref>    = *<x:ref>CHAR</x:ref>
639</artwork></figure>
640<t>  
641   Range units are defined in <xref target="range.units"/>. A recipient of a
642   <x:ref>206 (Partial Content)</x:ref> response containing a
643   <x:ref>Content-Range</x:ref> header field with a <x:ref>range unit</x:ref>
644   that the recipient does not understand &MUST-NOT; attempt to recombine it
645   with a stored representation. A proxy that receives such a message
646   &SHOULD; forward it downstream.
647</t>
648<t>
649   For byte ranges, a sender &SHOULD; indicate the complete length of the
650   representation from which the range has been extracted unless the complete
651   length is unknown or difficult to determine. An asterisk character ("*") in
652   place of the complete-length indicates that the representation length was
653   unknown when the header field was generated.
654</t>
655<t>
656   A Content-Range field value with a <x:ref>byte-range-resp</x:ref> that has
657   a <x:ref>last-byte-pos</x:ref> value less than its
658   <x:ref>first-byte-pos</x:ref> value, or a <x:ref>complete-length</x:ref>
659   value less than or equal to its <x:ref>last-byte-pos</x:ref> value, is
660   invalid. The recipient of an invalid <x:ref>Content-Range</x:ref> &MUST-NOT;
661   attempt to recombine the received content with a stored representation.
662</t>
663<t>
664   A server generating a <x:ref>206 (Partial Content)</x:ref> response to a
665   byte range request &MUST; send, in each body-part of a multipart response
666   or in the header block of a single part response, a Content-Range header
667   field containing a <x:ref>byte-range-resp</x:ref> value that reflects the
668   corresponding range being sent. The following example would apply
669   when the complete length of the selected representation is known by the
670   sender to be 1234 bytes:
671</t>
672<figure><artwork type="example">
673  Content-Range: bytes 42-1233/1234
674</artwork></figure>
675<t>
676   or this second example would apply when the complete length is unknown:
677</t>
678<figure><artwork type="example">
679  Content-Range: bytes 42-1233/*
680</artwork></figure>
681<t>
682   A server generating a <x:ref>416 (Range Not Satisfiable)</x:ref> response
683   to a byte range request &SHOULD; send a Content-Range header field with an
684   <x:ref>unsatisfied-range</x:ref> value, as in the following example:
685</t>
686<figure><artwork type="example">
687  Content-Range: bytes */1234
688</artwork></figure>
689<t>
690   The complete-length in a 416 response indicates the current length of the
691   selected representation, which will be known by the server generating the
692   response because that is how it determined the range to be unsatisfiable.
693</t>
694<t>
695   The "Content-Range" header field has no meaning for status codes that do
696   not explicitly describe its semantic. For this specification, only the
697   <x:ref>206 (Partial Content)</x:ref> and
698   <x:ref>416 (Range Not Satisfiable)</x:ref> status codes describe a meaning
699   for Content-Range.
700</t>
701<t>
702   More examples of Content-Range values, assuming that the representation
703   contains a total of 1234 bytes:
704   <list style="symbols">
705      <t>
706        The first 500 bytes:
707<figure><artwork type="example" x:indent-with="   ">
708  Content-Range: bytes 0-499/1234
709</artwork></figure>
710      </t>   
711      <t>
712        The second 500 bytes:
713<figure><artwork type="example" x:indent-with="   ">
714  Content-Range: bytes 500-999/1234
715</artwork></figure>
716      </t>   
717      <t>
718        All except for the first 500 bytes:
719<figure><artwork type="example" x:indent-with="   ">
720  Content-Range: bytes 500-1233/1234
721</artwork></figure>
722      </t>   
723      <t>
724        The last 500 bytes:
725<figure><artwork type="example" x:indent-with="   ">
726  Content-Range: bytes 734-1233/1234
727</artwork></figure>
728      </t>   
729   </list>
730</t>
731</section>
732
733<section title="Combining Ranges" anchor="combining.byte.ranges">
734<t>
735   A response might transfer only a subrange of a representation if the
736   connection closed prematurely or if the request used one or more Range
737   specifications.  After several such transfers, a client might have
738   received several ranges of the same representation.  These ranges can only
739   be safely combined if they all have in common the same strong validator,
740   where "strong validator" is defined to be either an entity-tag that is
741   not marked as weak (&entity-tags;) or, if no entity-tag is provided, a
742   <x:ref>Last-Modified</x:ref> value that is strong in the sense defined by
743   &lastmod-comparison;.
744</t>
745<t>
746   When a client receives an incomplete <x:ref>200 (OK)</x:ref> response or a
747   <x:ref>206 (Partial Content)</x:ref> response, and already has one or more
748   partial responses for the same method and effective request URI that have
749   the same strong validator as present in the new response,
750   the recipient &MAY; combine some or all of those responses into a set of
751   continuous ranges. A client &MUST-NOT; combine responses that differ in the
752   strong validator or that do not have a strong validator.
753</t>
754<t>
755   If the new response is an incomplete <x:ref>200 (OK)</x:ref> response, then
756   the header fields of that new response are used for any combined response
757   and replace those of the matching stored responses.
758</t>
759<t>
760   If the new response is a <x:ref>206 (Partial Content)</x:ref> response and
761   at least one of the matching stored responses is a <x:ref>200 (OK)</x:ref>,
762   then the combined response header fields consist of the most recent 200
763   response's header fields. If all of the matching stored responses are 206
764   responses, then the stored response with the most recent header fields is
765   used as the source of header fields for the combined response, except that
766   the client &MUST; use other header fields provided in the new response,
767   aside from <x:ref>Content-Range</x:ref>, to replace all instances of the
768   corresponding header fields in the stored response.
769</t>
770<t>
771   The combined response message body consists of the union of partial
772   content ranges in the new response and each of the selected responses.
773   If the union consists of the entire range of the representation, then the
774   client &MUST; record the combined response as if it were a complete
775   <x:ref>200 (OK)</x:ref> response, including a <x:ref>Content-Length</x:ref>
776   header field that reflects the complete length.
777   Otherwise, the client &MUST; record the set of continuous ranges as one of
778   the following:
779   an incomplete <x:ref>200 (OK)</x:ref> response if the combined response is
780   a prefix of the representation,
781   a single <x:ref>206 (Partial Content)</x:ref> response containing a
782   multipart/byteranges body, or
783   multiple <x:ref>206 (Partial Content)</x:ref> responses, each with one
784   continuous range that is indicated by a <x:ref>Content-Range</x:ref> header
785   field.
786</t>
787</section>
788</section>
789
790<section title="IANA Considerations" anchor="IANA.considerations">
791
792<section title="Range Unit Registry" anchor="range.unit.registry">
793<t>
794   The HTTP Range Unit Registry defines the name space for the range
795   unit names and refers to their corresponding specifications.
796   The registry is maintained at
797   <eref target="http://www.iana.org/assignments/http-range-specifiers"/>.
798</t>
799
800<section title="Procedure" anchor="range.unit.registry.procedure">
801<t>
802   Registration of an HTTP Range Unit &MUST; include the following fields:
803   <list style="symbols">
804     <t>Name</t>
805     <t>Description</t>
806     <t>Pointer to specification text</t>
807   </list>
808</t>
809<t>
810  Values to be added to this name space require IETF Review
811  (see <xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
812</t>
813</section>
814
815<section title="Registrations" anchor="range.unit.registration">
816<t>
817   The initial HTTP Range Unit Registry shall contain the registrations
818   below:
819</t>
820<texttable align="left" suppress-title="true" anchor="iana.range.units.table">
821   <ttcol>Range Specifier Name</ttcol>
822   <ttcol>Description</ttcol>
823   <ttcol>Reference</ttcol>
824
825   <c>bytes</c>
826   <c>a range of octets</c>
827   <c><xref target="range.units"/></c>
828
829   <c>none</c>
830   <c>reserved as keyword, indicating no ranges are supported</c>
831   <c><xref target="header.accept-ranges"/></c>
832</texttable>
833<t>
834   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
835</t>
836</section>
837</section>
838
839<section title="Status Code Registration" anchor="status.code.registration">
840<t>
841   The HTTP Status Code Registry located at <eref target="http://www.iana.org/assignments/http-status-codes"/>
842   shall be updated with the registrations below:
843</t>
844<?BEGININC p5-range.iana-status-codes ?>
845<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
846<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
847   <ttcol>Value</ttcol>
848   <ttcol>Description</ttcol>
849   <ttcol>Reference</ttcol>
850   <c>206</c>
851   <c>Partial Content</c>
852   <c>
853      <xref target="status.206"/>
854   </c>
855   <c>416</c>
856   <c>Range Not Satisfiable</c>
857   <c>
858      <xref target="status.416"/>
859   </c>
860</texttable>
861<!--(END)-->
862<?ENDINC p5-range.iana-status-codes ?>
863</section>
864
865<section title="Header Field Registration" anchor="header.field.registration">
866<t>
867   The Message Header Field Registry located at <eref target="http://www.iana.org/assignments/message-headers/message-header-index.html"/> shall be updated
868   with the permanent registrations below (see <xref target="BCP90"/>):
869</t>
870<?BEGININC p5-range.iana-headers ?>
871<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
872<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
873   <ttcol>Header Field Name</ttcol>
874   <ttcol>Protocol</ttcol>
875   <ttcol>Status</ttcol>
876   <ttcol>Reference</ttcol>
877
878   <c>Accept-Ranges</c>
879   <c>http</c>
880   <c>standard</c>
881   <c>
882      <xref target="header.accept-ranges"/>
883   </c>
884   <c>Content-Range</c>
885   <c>http</c>
886   <c>standard</c>
887   <c>
888      <xref target="header.content-range"/>
889   </c>
890   <c>If-Range</c>
891   <c>http</c>
892   <c>standard</c>
893   <c>
894      <xref target="header.if-range"/>
895   </c>
896   <c>Range</c>
897   <c>http</c>
898   <c>standard</c>
899   <c>
900      <xref target="header.range"/>
901   </c>
902</texttable>
903<!--(END)-->
904<?ENDINC p5-range.iana-headers ?>
905<t>
906   The change controller is: "IETF (iesg@ietf.org) - Internet Engineering Task Force".
907</t>
908</section>
909
910</section>
911
912<section title="Security Considerations" anchor="security.considerations">
913<t>
914   This section is meant to inform developers, information providers, and
915   users of known security concerns specific to the HTTP/1.1 range
916   request mechanisms. More general security considerations are addressed
917   in HTTP messaging &messaging; and semantics &semantics;.
918</t>
919
920<section title="Overlapping Ranges" anchor="overlapping.ranges">
921<t>
922   Range requests containing overlapping ranges can lead to a situation
923   where the server is sending far more data than the size of the complete
924   resource representation.
925</t>
926</section>
927</section>
928
929<section title="Acknowledgments" anchor="acks">
930<t>
931  See &acks;.
932</t>
933</section>
934</middle>
935<back>
936
937<references title="Normative References">
938
939<reference anchor="Part1">
940  <front>
941    <title>Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing</title>
942    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
943      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
944      <address><email>fielding@gbiv.com</email></address>
945    </author>
946    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
947      <organization abbrev="greenbytes">greenbytes GmbH</organization>
948      <address><email>julian.reschke@greenbytes.de</email></address>
949    </author>
950    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
951  </front>
952  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
953  <x:source href="p1-messaging.xml" basename="p1-messaging">
954    <x:defines>Content-Length</x:defines>
955  </x:source>
956</reference>
957
958<reference anchor="Part2">
959  <front>
960    <title>Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content</title>
961    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
962      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
963      <address><email>fielding@gbiv.com</email></address>
964    </author>
965    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
966      <organization abbrev="greenbytes">greenbytes GmbH</organization>
967      <address><email>julian.reschke@greenbytes.de</email></address>
968    </author>
969    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
970  </front>
971  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"/>
972  <x:source href="p2-semantics.xml" basename="p2-semantics">
973    <x:defines>200 (OK)</x:defines>
974    <x:defines>410 (Gone)</x:defines>
975    <x:defines>Content-Location</x:defines>
976    <x:defines>Content-Type</x:defines>
977    <x:defines>Location</x:defines>
978    <x:defines>Vary</x:defines>
979  </x:source>
980</reference>
981
982<reference anchor="Part4">
983  <front>
984    <title>Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests</title>
985    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
986      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
987      <address><email>fielding@gbiv.com</email></address>
988    </author>
989    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
990      <organization abbrev="greenbytes">greenbytes GmbH</organization>
991      <address><email>julian.reschke@greenbytes.de</email></address>
992    </author>
993    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
994  </front>
995  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
996  <x:source href="p4-conditional.xml" basename="p4-conditional">
997    <x:defines>304 (Not Modified)</x:defines>
998    <x:defines>ETag</x:defines>
999    <x:defines>If-Match</x:defines>
1000    <x:defines>If-Modified-Since</x:defines>
1001    <x:defines>If-None-Match</x:defines>
1002    <x:defines>If-Unmodified-Since</x:defines>
1003    <x:defines>Last-Modified</x:defines>
1004  </x:source>
1005</reference>
1006
1007<reference anchor="Part6">
1008  <front>
1009    <title>Hypertext Transfer Protocol (HTTP/1.1): Caching</title>
1010    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
1011      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1012      <address><email>fielding@gbiv.com</email></address>
1013    </author>
1014    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
1015      <organization>Akamai</organization>
1016      <address><email>mnot@mnot.net</email></address>
1017    </author>
1018    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1019      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1020      <address><email>julian.reschke@greenbytes.de</email></address>
1021    </author>
1022    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1023  </front>
1024  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
1025  <x:source href="p6-cache.xml" basename="p6-cache">
1026    <x:defines>Cache-Control</x:defines>
1027    <x:defines>Expires</x:defines>
1028  </x:source>
1029</reference>
1030
1031<reference anchor="RFC2046">
1032  <front>
1033    <title abbrev="Media Types">Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types</title>
1034    <author initials="N." surname="Freed" fullname="Ned Freed">
1035      <organization>Innosoft International, Inc.</organization>
1036      <address><email>ned@innosoft.com</email></address>
1037    </author>
1038    <author initials="N." surname="Borenstein" fullname="Nathaniel S. Borenstein">
1039      <organization>First Virtual Holdings</organization>
1040      <address><email>nsb@nsb.fv.com</email></address>
1041    </author>
1042    <date month="November" year="1996"/>
1043  </front>
1044  <seriesInfo name="RFC" value="2046"/>
1045</reference>
1046
1047<reference anchor="RFC2119">
1048  <front>
1049    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
1050    <author initials="S." surname="Bradner" fullname="Scott Bradner">
1051      <organization>Harvard University</organization>
1052      <address><email>sob@harvard.edu</email></address>
1053    </author>
1054    <date month="March" year="1997"/>
1055  </front>
1056  <seriesInfo name="BCP" value="14"/>
1057  <seriesInfo name="RFC" value="2119"/>
1058</reference>
1059
1060<reference anchor="RFC5234">
1061  <front>
1062    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
1063    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
1064      <organization>Brandenburg InternetWorking</organization>
1065      <address>
1066        <email>dcrocker@bbiw.net</email>
1067      </address> 
1068    </author>
1069    <author initials="P." surname="Overell" fullname="Paul Overell">
1070      <organization>THUS plc.</organization>
1071      <address>
1072        <email>paul.overell@thus.net</email>
1073      </address>
1074    </author>
1075    <date month="January" year="2008"/>
1076  </front>
1077  <seriesInfo name="STD" value="68"/>
1078  <seriesInfo name="RFC" value="5234"/>
1079</reference>
1080
1081</references>
1082
1083<references title="Informative References">
1084
1085<reference anchor="RFC2616">
1086  <front>
1087    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
1088    <author initials="R." surname="Fielding" fullname="R. Fielding">
1089      <organization>University of California, Irvine</organization>
1090      <address><email>fielding@ics.uci.edu</email></address>
1091    </author>
1092    <author initials="J." surname="Gettys" fullname="J. Gettys">
1093      <organization>W3C</organization>
1094      <address><email>jg@w3.org</email></address>
1095    </author>
1096    <author initials="J." surname="Mogul" fullname="J. Mogul">
1097      <organization>Compaq Computer Corporation</organization>
1098      <address><email>mogul@wrl.dec.com</email></address>
1099    </author>
1100    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
1101      <organization>MIT Laboratory for Computer Science</organization>
1102      <address><email>frystyk@w3.org</email></address>
1103    </author>
1104    <author initials="L." surname="Masinter" fullname="L. Masinter">
1105      <organization>Xerox Corporation</organization>
1106      <address><email>masinter@parc.xerox.com</email></address>
1107    </author>
1108    <author initials="P." surname="Leach" fullname="P. Leach">
1109      <organization>Microsoft Corporation</organization>
1110      <address><email>paulle@microsoft.com</email></address>
1111    </author>
1112    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
1113      <organization>W3C</organization>
1114      <address><email>timbl@w3.org</email></address>
1115    </author>
1116    <date month="June" year="1999"/>
1117  </front>
1118  <seriesInfo name="RFC" value="2616"/>
1119</reference>
1120
1121<reference anchor='BCP90'>
1122  <front>
1123    <title>Registration Procedures for Message Header Fields</title>
1124    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
1125      <organization>Nine by Nine</organization>
1126      <address><email>GK-IETF@ninebynine.org</email></address>
1127    </author>
1128    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
1129      <organization>BEA Systems</organization>
1130      <address><email>mnot@pobox.com</email></address>
1131    </author>
1132    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
1133      <organization>HP Labs</organization>
1134      <address><email>JeffMogul@acm.org</email></address>
1135    </author>
1136    <date year='2004' month='September' />
1137  </front>
1138  <seriesInfo name='BCP' value='90' />
1139  <seriesInfo name='RFC' value='3864' />
1140</reference>
1141
1142<reference anchor="BCP13">
1143  <front>
1144    <title>Media Type Specifications and Registration Procedures</title>
1145    <author initials="N." surname="Freed" fullname="N. Freed">
1146      <organization>Sun Microsystems</organization>
1147      <address>
1148        <email>ned.freed@mrochek.com</email>
1149      </address>
1150    </author>
1151    <author initials="J." surname="Klensin" fullname="J. Klensin">
1152      <address>
1153        <email>klensin+ietf@jck.com</email>
1154      </address>
1155    </author>
1156    <date year="2005" month="December"/>
1157  </front>
1158  <seriesInfo name="BCP" value="13"/>
1159  <seriesInfo name="RFC" value="4288"/>
1160</reference>
1161
1162<reference anchor='RFC5226'>
1163  <front>
1164    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
1165    <author initials='T.' surname='Narten' fullname='T. Narten'>
1166      <organization>IBM</organization>
1167      <address><email>narten@us.ibm.com</email></address>
1168    </author>
1169    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
1170      <organization>Google</organization>
1171      <address><email>Harald@Alvestrand.no</email></address>
1172    </author>
1173    <date year='2008' month='May' />
1174  </front>
1175  <seriesInfo name='BCP' value='26' />
1176  <seriesInfo name='RFC' value='5226' />
1177</reference>
1178
1179</references>
1180
1181<section title="Internet Media Type multipart/byteranges" anchor="internet.media.type.multipart.byteranges">
1182<iref item="Media Type" subitem="multipart/byteranges" primary="true"/>
1183<iref item="multipart/byteranges Media Type" primary="true"/>
1184<t>
1185   When an HTTP <x:ref>206 (Partial Content)</x:ref> response message includes the
1186   content of multiple ranges (a response to a request for multiple
1187   non-overlapping ranges), these are transmitted as a multipart
1188   message body (<xref target="RFC2046" x:fmt="," x:sec="5.1"/>). The media type for this purpose is called
1189   "multipart/byteranges".  The following is to be registered with IANA <xref target="BCP13"/>.
1190</t>
1191<t>
1192   The multipart/byteranges media type includes one or more parts, each
1193   with its own <x:ref>Content-Type</x:ref> and <x:ref>Content-Range</x:ref>
1194   fields. The required boundary parameter specifies the boundary string used
1195   to separate each body-part.
1196</t>
1197<t>
1198  <list style="hanging" x:indent="12em">
1199    <t hangText="Type name:">
1200      multipart
1201    </t>
1202    <t hangText="Subtype name:">
1203      byteranges
1204    </t>
1205    <t hangText="Required parameters:">
1206      boundary
1207    </t>
1208    <t hangText="Optional parameters:">
1209      none
1210    </t>
1211    <t hangText="Encoding considerations:">
1212      only "7bit", "8bit", or "binary" are permitted
1213    </t>
1214    <t hangText="Security considerations:">
1215      none
1216    </t>
1217    <t hangText="Interoperability considerations:">
1218      none
1219    </t>
1220    <t hangText="Published specification:">
1221      This specification (see <xref target="internet.media.type.multipart.byteranges"/>).
1222    </t>
1223    <t hangText="Applications that use this media type:">
1224      HTTP components supporting multiple ranges in a single request.
1225    </t>
1226    <t hangText="Additional information:">
1227      <list style="hanging">
1228        <t hangText="Magic number(s):">none</t>
1229        <t hangText="File extension(s):">none</t>
1230        <t hangText="Macintosh file type code(s):">none</t>
1231      </list>
1232    </t>
1233    <t hangText="Person and email address to contact for further information:">
1234      See Authors Section.
1235    </t>
1236    <t hangText="Intended usage:">
1237      COMMON
1238    </t>
1239    <t hangText="Restrictions on usage:">
1240      none
1241    </t>
1242    <t hangText="Author/Change controller:">
1243      IESG
1244    </t>
1245  </list>
1246</t>
1247<x:note>
1248  <t>
1249    &Note; Despite the name "multipart/byteranges" is not limited to the byte ranges only.
1250  </t>
1251</x:note>
1252<figure><preamble>
1253   For example:
1254</preamble><artwork type="example">
1255  HTTP/1.1 206 Partial Content
1256  Date: Wed, 15 Nov 1995 06:25:24 GMT
1257  Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
1258  Content-Length: 1741
1259  Content-Type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
1260 
1261  --THIS_STRING_SEPARATES
1262  Content-Type: application/pdf
1263  Content-Range: bytes 500-999/8000
1264 
1265  ...the first range...
1266  --THIS_STRING_SEPARATES
1267  Content-Type: application/pdf
1268  Content-Range: bytes 7000-7999/8000
1269 
1270  ...the second range
1271  --THIS_STRING_SEPARATES--
1272</artwork></figure>
1273<figure><preamble>
1274   Another example, using the "exampleunit" range unit:
1275</preamble>
1276<artwork type="example">
1277  HTTP/1.1 206 Partial Content
1278  Date: Tue, 14 Nov 1995 06:25:24 GMT
1279  Last-Modified: Tue, 14 July 04:58:08 GMT
1280  Content-Length: 2331785
1281  Content-Type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
1282 
1283  --THIS_STRING_SEPARATES
1284  Content-Type: video/example
1285  Content-Range: exampleunit 1.2-4.3/25
1286 
1287  ...the first range...
1288  --THIS_STRING_SEPARATES
1289  Content-Type: video/example
1290  Content-Range: exampleunit 11.2-14.3/25
1291 
1292  ...the second range
1293  --THIS_STRING_SEPARATES--
1294</artwork>
1295</figure>
1296<t>
1297  Notes:
1298  <list style="numbers">
1299      <t>Additional CRLFs &MAY; precede the first boundary string in the body.</t>
1300
1301      <t>Although <xref target="RFC2046"/> permits the boundary string to be
1302         quoted, some existing implementations handle a quoted boundary
1303         string incorrectly.</t>
1304
1305      <t>A number of clients and servers were coded to an early draft
1306         of the byteranges specification to use a media type of
1307         multipart/x-byteranges<iref item="multipart/x-byteranges Media Type"/><iref item="Media Type" subitem="multipart/x-byteranges"/>, which is almost, but not quite
1308         compatible with the version documented in HTTP/1.1.</t>
1309  </list>
1310</t>
1311</section>
1312
1313<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
1314
1315<t>
1316  A weak validator cannot be used in a <x:ref>206</x:ref> response.
1317  (<xref target="status.206"/>)
1318</t>
1319<t>
1320  The Content-Range header field only has meaning when the status code
1321  explicitly defines its use.
1322  (<xref target="header.content-range" />)
1323</t>
1324<t>
1325  Servers are given more leeway in how they respond to a range request,
1326  in order to mitigate abuse by malicious (or just greedy) clients.
1327</t>
1328<t>
1329  multipart/byteranges can consist of a single part.
1330  (<xref target="internet.media.type.multipart.byteranges"/>)
1331</t>
1332<t>
1333  This specification introduces a Range Specifier Registry.
1334  (<xref target="range.unit.registry"/>)
1335</t>
1336</section>
1337
1338<section title="Imported ABNF" anchor="imported.abnf">
1339  <x:anchor-alias value="ALPHA"/>
1340  <x:anchor-alias value="CHAR"/>
1341  <x:anchor-alias value="CR"/>
1342  <x:anchor-alias value="DIGIT"/>
1343  <x:anchor-alias value="LF"/>
1344  <x:anchor-alias value="OCTET"/>
1345  <x:anchor-alias value="SP"/>
1346  <x:anchor-alias value="VCHAR"/>
1347  <x:anchor-alias value="token"/>
1348  <x:anchor-alias value="OWS"/>
1349  <x:anchor-alias value="HTTP-date"/>
1350  <x:anchor-alias value="entity-tag"/>
1351<t>
1352  The following core rules are included by
1353  reference, as defined in <xref target="RFC5234" x:fmt="of" x:sec="B.1"/>:
1354  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
1355  DIGIT (decimal 0-9), DQUOTE (double quote),
1356  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
1357  OCTET (any 8-bit sequence of data), SP (space), and
1358  VCHAR (any visible US-ASCII character).
1359</t>
1360<t>
1361  Note that all rules derived from <x:ref>token</x:ref> are to
1362  be compared case-insensitively, like <x:ref>range-unit</x:ref> and
1363  <x:ref>acceptable-ranges</x:ref>.
1364</t>
1365<t>
1366  The rules below are defined in <xref target="Part1"/>:
1367</t>
1368<figure><artwork type="abnf2616">
1369  <x:ref>OWS</x:ref>        = &lt;OWS, defined in &whitespace;&gt;
1370  <x:ref>token</x:ref>      = &lt;token, defined in &field-components;&gt;
1371</artwork></figure>
1372<t>
1373  The rules below are defined in other parts:
1374</t>
1375<figure><artwork type="abnf2616">
1376  <x:ref>HTTP-date</x:ref>  = &lt;HTTP-date, defined in &http-date;&gt;
1377  <x:ref>entity-tag</x:ref> = &lt;entity-tag, defined in &entity-tags;&gt;
1378</artwork></figure>
1379</section>
1380
1381<?BEGININC p5-range.abnf-appendix ?>
1382<section xmlns:x="http://purl.org/net/xml2rfc/ext" title="Collected ABNF" anchor="collected.abnf">
1383<figure>
1384<artwork type="abnf" name="p5-range.parsed-abnf">
1385<x:ref>Accept-Ranges</x:ref> = acceptable-ranges
1386
1387<x:ref>Content-Range</x:ref> = byte-content-range / other-content-range
1388
1389<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part2], Section 7.1.1.1&gt;
1390
1391<x:ref>If-Range</x:ref> = entity-tag / HTTP-date
1392
1393<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 3.2.3&gt;
1394
1395<x:ref>Range</x:ref> = byte-ranges-specifier / other-ranges-specifier
1396
1397<x:ref>acceptable-ranges</x:ref> = ( *( "," OWS ) range-unit *( OWS "," [ OWS
1398 range-unit ] ) ) / "none"
1399
1400<x:ref>byte-content-range</x:ref> = bytes-unit SP ( byte-range-resp /
1401 unsatisfied-range )
1402<x:ref>byte-range</x:ref> = first-byte-pos "-" last-byte-pos
1403<x:ref>byte-range-resp</x:ref> = byte-range "/" ( complete-length / "*" )
1404<x:ref>byte-range-set</x:ref> = *( "," OWS ) ( byte-range-spec /
1405 suffix-byte-range-spec ) *( OWS "," [ OWS ( byte-range-spec /
1406 suffix-byte-range-spec ) ] )
1407<x:ref>byte-range-spec</x:ref> = first-byte-pos "-" [ last-byte-pos ]
1408<x:ref>byte-ranges-specifier</x:ref> = bytes-unit "=" byte-range-set
1409<x:ref>bytes-unit</x:ref> = "bytes"
1410
1411<x:ref>complete-length</x:ref> = 1*DIGIT
1412
1413<x:ref>entity-tag</x:ref> = &lt;entity-tag, defined in [Part4], Section 2.3&gt;
1414
1415<x:ref>first-byte-pos</x:ref> = 1*DIGIT
1416
1417<x:ref>last-byte-pos</x:ref> = 1*DIGIT
1418
1419<x:ref>other-content-range</x:ref> = other-range-unit SP other-range-resp
1420<x:ref>other-range-resp</x:ref> = *CHAR
1421<x:ref>other-range-set</x:ref> = 1*CHAR
1422<x:ref>other-range-unit</x:ref> = token
1423<x:ref>other-ranges-specifier</x:ref> = other-range-unit "=" other-range-set
1424
1425<x:ref>range-unit</x:ref> = bytes-unit / other-range-unit
1426
1427<x:ref>suffix-byte-range-spec</x:ref> = "-" suffix-length
1428<x:ref>suffix-length</x:ref> = 1*DIGIT
1429
1430<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 3.2.6&gt;
1431
1432<x:ref>unsatisfied-range</x:ref> = "*/" complete-length
1433</artwork>
1434</figure>
1435</section>
1436<?ENDINC p5-range.abnf-appendix ?>
1437
1438
1439<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
1440<t>
1441  Changes up to the first Working Group Last Call draft are summarized
1442  in <eref target="http://tools.ietf.org/html/draft-ietf-httpbis-p5-range-19#appendix-D"/>.
1443</t>
1444
1445<section title="Since draft-ietf-httpbis-p5-range-19" anchor="changes.since.19">
1446<t>
1447  Closed issues:
1448  <list style="symbols">
1449    <t>
1450      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/358"/>:
1451      "ABNF list expansion code problem"
1452    </t>
1453    <t>
1454      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/361"/>:
1455      "ABNF requirements for recipients"
1456    </t>
1457    <t>
1458      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/367"/>:
1459      "reserve 'none' as byte range unit"
1460    </t>
1461    <t>
1462      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/368"/>:
1463      "note introduction of new IANA registries as normative changes"
1464    </t>
1465    <t>
1466      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/369"/>:
1467      "range units vs leading zeroes vs size"
1468    </t>
1469  </list>
1470</t>
1471</section>
1472
1473<section title="Since draft-ietf-httpbis-p5-range-20" anchor="changes.since.20">
1474<t>
1475  <list style="symbols">
1476    <t>
1477      Conformance criteria and considerations regarding error handling are
1478      now defined in Part 1.
1479    </t>
1480  </list>
1481</t>
1482</section>
1483
1484<section title="Since draft-ietf-httpbis-p5-range-21" anchor="changes.since.21">
1485<t>
1486  None yet.
1487</t>
1488</section>
1489
1490</section>
1491
1492</back>
1493</rfc>
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