source: draft-ietf-httpbis/latest/p5-range.xml @ 2333

Last change on this file since 2333 was 2333, checked in by julian.reschke@…, 6 years ago

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

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[29]1<?xml version="1.0" encoding="utf-8"?>
[101]2<?xml-stylesheet type='text/xsl' href='../myxml2rfc.xslt'?>
[8]3<!DOCTYPE rfc [
4  <!ENTITY MAY "<bcp14 xmlns=''>MAY</bcp14>">
5  <!ENTITY MUST "<bcp14 xmlns=''>MUST</bcp14>">
6  <!ENTITY MUST-NOT "<bcp14 xmlns=''>MUST NOT</bcp14>">
7  <!ENTITY OPTIONAL "<bcp14 xmlns=''>OPTIONAL</bcp14>">
8  <!ENTITY RECOMMENDED "<bcp14 xmlns=''>RECOMMENDED</bcp14>">
9  <!ENTITY REQUIRED "<bcp14 xmlns=''>REQUIRED</bcp14>">
10  <!ENTITY SHALL "<bcp14 xmlns=''>SHALL</bcp14>">
11  <!ENTITY SHALL-NOT "<bcp14 xmlns=''>SHALL NOT</bcp14>">
12  <!ENTITY SHOULD "<bcp14 xmlns=''>SHOULD</bcp14>">
13  <!ENTITY SHOULD-NOT "<bcp14 xmlns=''>SHOULD NOT</bcp14>">
[29]14  <!ENTITY ID-VERSION "latest">
[2333]15  <!ENTITY ID-MONTH "August">
[2080]16  <!ENTITY ID-YEAR "2013">
[1692]17  <!ENTITY Note "<x:h xmlns:x=''>Note:</x:h>">
[1452]18  <!ENTITY architecture               "<xref target='Part1' x:rel='#architecture' xmlns:x=''/>">
[1875]19  <!ENTITY conformance                "<xref target='Part1' x:rel='#conformance' xmlns:x=''/>">
[424]20  <!ENTITY notation                   "<xref target='Part1' x:rel='#notation' xmlns:x=''/>">
[1518]21  <!ENTITY abnf-extension             "<xref target='Part1' x:rel='#abnf.extension' xmlns:x=''/>">
[1364]22  <!ENTITY acks                       "<xref target='Part1' x:rel='#acks' xmlns:x=''/>">
[1518]23  <!ENTITY whitespace                 "<xref target='Part1' x:rel='#whitespace' xmlns:x=''/>">
24  <!ENTITY field-components           "<xref target='Part1' x:rel='#field.components' xmlns:x=''/>">
[31]25  <!ENTITY messaging                  "<xref target='Part1' xmlns:x=''/>">
[2069]26  <!ENTITY semantics                  "<xref target='Part2' xmlns:x=''/>">
[2144]27  <!ENTITY http-date                  "<xref target='Part2' x:rel='' xmlns:x=''/>">
28  <!ENTITY representation             "<xref target='Part2' x:rel='#representations' xmlns:x=''/>">
[1260]29  <!ENTITY entity-tags                "<xref target='Part4' x:rel='#header.etag' xmlns:x=''/>">
[31]30  <!ENTITY weak-and-strong-validators "<xref target='Part4' x:rel='#weak.and.strong.validators' xmlns:x=''/>">
[1260]31  <!ENTITY lastmod-comparison         "<xref target='Part4' x:rel='#lastmod.comparison' xmlns:x=''/>">
[1524]32  <!ENTITY p6-heuristic               "<xref target='Part6' x:rel='#heuristic.freshness' xmlns:x=''/>">
34<?rfc toc="yes" ?>
[29]35<?rfc symrefs="yes" ?>
36<?rfc sortrefs="yes" ?>
[8]37<?rfc compact="yes"?>
38<?rfc subcompact="no" ?>
39<?rfc linkmailto="no" ?>
40<?rfc editing="no" ?>
[203]41<?rfc comments="yes"?>
42<?rfc inline="yes"?>
[799]43<?rfc rfcedstyle="yes"?>
[8]44<?rfc-ext allow-markup-in-artwork="yes" ?>
45<?rfc-ext include-references-in-index="yes" ?>
[1477]46<rfc obsoletes="2616" category="std" x:maturity-level="proposed"
47     ipr="pre5378Trust200902" docName="draft-ietf-httpbis-p5-range-&ID-VERSION;"
48     xmlns:x=''>
[1472]49<x:link rel="prev" basename="p4-conditional"/>
50<x:link rel="next" basename="p6-cache"/>
[1522]51<x:feedback template="{docname},%20%22{section}%22&amp;body=&lt;{ref}&gt;:"/>
[1864]54  <title abbrev="HTTP/1.1 Range Requests">Hypertext Transfer Protocol (HTTP/1.1): Range Requests</title>
[29]56  <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
[1106]57    <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[8]58    <address>
59      <postal>
[1106]60        <street>345 Park Ave</street>
61        <city>San Jose</city>
[8]62        <region>CA</region>
[1106]63        <code>95110</code>
[29]64        <country>USA</country>
[8]65      </postal>
[29]66      <email></email>
67      <uri></uri>
[8]68    </address>
69  </author>
[95]71  <author initials="Y." surname="Lafon" fullname="Yves Lafon" role="editor">
[94]72    <organization abbrev="W3C">World Wide Web Consortium</organization>
73    <address>
74      <postal>
75        <street>W3C / ERCIM</street>
76        <street>2004, rte des Lucioles</street>
77        <city>Sophia-Antipolis</city>
78        <region>AM</region>
79        <code>06902</code>
80        <country>France</country>
81      </postal>
82      <email></email>
83      <uri></uri>
84    </address>
85  </author>
[95]87  <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
88    <organization abbrev="greenbytes">greenbytes GmbH</organization>
89    <address>
90      <postal>
91        <street>Hafenweg 16</street>
92        <city>Muenster</city><region>NW</region><code>48155</code>
93        <country>Germany</country>
94      </postal>
[609]95      <email></email>
96      <uri></uri>
[95]97    </address>
98  </author>
[31]100  <date month="&ID-MONTH;" year="&ID-YEAR;"/>
[440]101  <workgroup>HTTPbis Working Group</workgroup>
[1373]105   The Hypertext Transfer Protocol (HTTP) is an application-level protocol for
[1808]106   distributed, collaborative, hypertext information systems. This document
107   defines range requests and the rules for constructing and combining
108   responses to those requests.
112<note title="Editorial Note (To be removed by RFC Editor)">
113  <t>
[1764]114    Discussion of this draft takes place on the HTTPBIS working group
[1268]115    mailing list (, which is archived at
116    <eref target=""/>.
117  </t>
118  <t>
119    The current issues list is at
120    <eref target=""/> and related
121    documents (including fancy diffs) can be found at
[324]122    <eref target=""/>.
[36]123  </t>
[153]124  <t>
[2304]125    The changes in this draft are summarized in <xref target="changes.since.23"/>.
[153]126  </t>
130<section title="Introduction" anchor="introduction">
[2144]132   Hypertext Transfer Protocol (HTTP) clients often encounter interrupted data
133   transfers as a result of canceled requests or dropped connections. When a
134   client has stored a partial representation, it is desirable to request the
135   remainder of that representation in a subsequent request rather than
136   transfer the entire representation. Likewise, devices with limited local
137   storage might benefit from being able to request only a subset of a larger
138   representation, such as a single page of a very large document, or the
139   dimensions of an embedded image.
[2144]142   This document defines HTTP/1.1 range requests, partial responses, and the
[2217]143   multipart/byteranges media type. Range requests are an &OPTIONAL; feature
[2144]144   of HTTP, designed so that recipients not implementing this feature (or not
145   supporting it for the target resource) can respond as if it is a normal
146   GET request without impacting interoperability. Partial responses are
147   indicated by a distinct status code to not be mistaken for full responses
148   by caches that might not implement the feature.
[2144]151   Although the range request mechanism is designed to allow for
[158]152   extensible range types, this specification only defines requests for
153   byte ranges.
[1875]156<section title="Conformance and Error Handling" anchor="conformance">
158   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
159   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
160   document are to be interpreted as described in <xref target="RFC2119"/>.
[1875]163   Conformance criteria and considerations regarding error handling
164   are defined in &conformance;.
[424]168<section title="Syntax Notation" anchor="notation">
[1518]170   This specification uses the Augmented Backus-Naur Form (ABNF) notation
171   of <xref target="RFC5234"/> with the list rule extension defined in
[1805]172   &notation;. <xref target="imported.abnf"/> describes rules imported from
173   other documents. <xref target="collected.abnf"/> shows the collected ABNF
[1518]174   with the list rule expanded.
[8]180<section title="Range Units" anchor="range.units">
[229]181  <x:anchor-alias value="range-unit"/>
[2135]182  <x:anchor-alias value="range unit"/>
[2135]184   A representation can be partitioned into subranges according to various
185   structural units, depending on the structure inherent in the
[2144]186   representation's media type. This "<x:dfn>range unit</x:dfn>" is used
187   in the <x:ref>Accept-Ranges</x:ref> (<xref target="header.accept-ranges"/>)
188   response header field to advertise support for range requests, the
189   <x:ref>Range</x:ref> (<xref target="header.range"/>) request header field
190   to delineate the parts of a representation that are requested, and the
[1738]191   <x:ref>Content-Range</x:ref> (<xref target="header.content-range"/>)
[2144]192   payload header field to describe which part of a representation is being
193   transferred.
[2144]195<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="range-unit"/><iref item="Grammar" subitem="bytes-unit"/><iref item="Grammar" subitem="other-range-unit"/>
[334]196  <x:ref>range-unit</x:ref>       = <x:ref>bytes-unit</x:ref> / <x:ref>other-range-unit</x:ref>
199<section title="Byte Ranges" anchor="byte.ranges">
[2144]200  <x:anchor-alias value="bytes-unit"/>
[2144]202   Since representation data is transferred in payloads as a sequence of
203   octets, a byte range is a meaningful substructure for any representation
204   transferable over HTTP (&representation;). We define the "bytes" range
205   unit for expressing subranges of the data's octet sequence.
[2144]207<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="bytes-unit"/>
208  <x:ref>bytes-unit</x:ref>       = "bytes"
[2140]210<t anchor="rule.ranges-specifier">
211  <x:anchor-alias value="byte-range-set"/>
212  <x:anchor-alias value="byte-range-spec"/>
213  <x:anchor-alias value="byte-ranges-specifier"/>
214  <x:anchor-alias value="first-byte-pos"/>
215  <x:anchor-alias value="last-byte-pos"/>
216  <x:anchor-alias value="ranges-specifier"/>
217  <x:anchor-alias value="suffix-byte-range-spec"/>
218  <x:anchor-alias value="suffix-length"/>
[2296]219   A byte range request can specify a single range of bytes, or a set
[2140]220   of ranges within a single representation.
222<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"/>
223  <x:ref>byte-ranges-specifier</x:ref> = <x:ref>bytes-unit</x:ref> "=" <x:ref>byte-range-set</x:ref>
224  <x:ref>byte-range-set</x:ref>  = 1#( <x:ref>byte-range-spec</x:ref> / <x:ref>suffix-byte-range-spec</x:ref> )
225  <x:ref>byte-range-spec</x:ref> = <x:ref>first-byte-pos</x:ref> "-" [ <x:ref>last-byte-pos</x:ref> ]
226  <x:ref>first-byte-pos</x:ref>  = 1*<x:ref>DIGIT</x:ref>
227  <x:ref>last-byte-pos</x:ref>   = 1*<x:ref>DIGIT</x:ref>
[2150]230   The <x:ref>first-byte-pos</x:ref> value in a <x:ref>byte-range-spec</x:ref>
231   gives the byte-offset of the first byte in a range.
232   The <x:ref>last-byte-pos</x:ref> value gives the byte-offset of the last
233   byte in the range; that is, the byte positions specified are inclusive.
234   Byte offsets start at zero.
[2150]237   Examples of <x:ref>byte-ranges-specifier</x:ref> values:
[2145]238  <list style="symbols">
239     <t>The first 500 bytes (byte offsets 0-499, inclusive):
240<figure><artwork type="example" x:indent-with="   ">
241  bytes=0-499
243    </t>
244     <t>The second 500 bytes (byte offsets 500-999, inclusive):
245<figure><artwork type="example" x:indent-with="   ">
246  bytes=500-999
248    </t>
249  </list>
[2150]252   A <x:ref>byte-range-spec</x:ref> is invalid if the
253   <x:ref>last-byte-pos</x:ref> value is present and less than the
254   <x:ref>first-byte-pos</x:ref>.
[2150]257   A client can limit the number of bytes requested without knowing the size
258   of the selected representation.
259   If the <x:ref>last-byte-pos</x:ref> value is absent, or if the value is
260   greater than or equal to the current length of the representation data, the
261   byte range is interpreted as the remainder of the representation (i.e., the
262   server replaces the value of <x:ref>last-byte-pos</x:ref> with a value that
263   is one less than the current length of the selected representation).
[2150]266   A client can request the last N bytes of the selected representation using
267   a <x:ref>suffix-byte-range-spec</x:ref>.
269<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="suffix-byte-range-spec"/><iref primary="true" item="Grammar" subitem="suffix-length"/>
270  <x:ref>suffix-byte-range-spec</x:ref> = "-" <x:ref>suffix-length</x:ref>
271  <x:ref>suffix-length</x:ref> = 1*<x:ref>DIGIT</x:ref>
[2150]274   If the selected representation is shorter than the specified
275   <x:ref>suffix-length</x:ref>, the entire representation is used.
278   Additional examples, assuming a representation of length 10000:
[2140]279  <list style="symbols">
280     <t>The final 500 bytes (byte offsets 9500-9999, inclusive):
281<figure><artwork type="example" x:indent-with="   ">
282  bytes=-500
284    Or:
285<figure><artwork type="example" x:indent-with="   ">
286  bytes=9500-
288    </t>
289     <t>The first and last bytes only (bytes 0 and 9999):
290<figure><artwork type="example" x:indent-with="   ">
291  bytes=0-0,-1
293     </t>
[2144]294     <t>Other valid (but not canonical) specifications of the second 500
[2140]295        bytes (byte offsets 500-999, inclusive):
296<figure><artwork type="example" x:indent-with="   ">
297  bytes=500-600,601-999
298  bytes=500-700,601-999
300     </t>
301  </list>
[2150]304   If a valid <x:ref>byte-range-set</x:ref> includes at least one
305   <x:ref>byte-range-spec</x:ref> with a <x:ref>first-byte-pos</x:ref> that is
306   less than the current length of the representation, or at least one
307   <x:ref>suffix-byte-range-spec</x:ref> with a non-zero
308   <x:ref>suffix-length</x:ref>, then the <x:ref>byte-range-set</x:ref> is
309   satisfiable. Otherwise, the <x:ref>byte-range-set</x:ref> is unsatisfiable.
312   In the byte range syntax, <x:ref>first-byte-pos</x:ref>,
313   <x:ref>last-byte-pos</x:ref>, and <x:ref>suffix-length</x:ref> are
[2150]314   expressed as decimal number of octets. Since there is no predefined limit
315   to the length of a payload, recipients ought to anticipate potentially
316   large decimal numerals and prevent parsing errors due to integer conversion
317   overflows.
321<section title="Other Range Units" anchor="range.units.other">
[2144]322  <x:anchor-alias value="other-range-unit"/>
[2144]324  Range units are intended to be extensible.  New range units ought to be
325  registered with IANA, as defined in <xref target="range.unit.registry"/>.
[2144]327<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="other-range-unit"/>
328  <x:ref>other-range-unit</x:ref> = <x:ref>token</x:ref>
[2142]332<section title="Accept-Ranges" anchor="header.accept-ranges">
333  <iref primary="true" item="Accept-Ranges header field" x:for-anchor=""/>
334  <x:anchor-alias value="Accept-Ranges"/>
335  <x:anchor-alias value="acceptable-ranges"/>
[2150]337   The "Accept-Ranges" header field allows a server to indicate that it
338   supports range requests for the target resource.
340<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Accept-Ranges"/><iref primary="true" item="Grammar" subitem="acceptable-ranges"/>
341  <x:ref>Accept-Ranges</x:ref>     = <x:ref>acceptable-ranges</x:ref>
342  <x:ref>acceptable-ranges</x:ref> = 1#<x:ref>range-unit</x:ref> / "none"
[2150]345   Origin servers that support byte-range requests &MAY; send
347<figure><artwork type="example">
348  Accept-Ranges: bytes
351   but are not required to do so. Clients &MAY; generate range
352   requests without having received this header field for the resource
353   involved. Range units are defined in <xref target="range.units"/>.
[2150]356   Servers that do not support any kind of range request for the target
357   resource resource &MAY; send
359<figure><artwork type="example">
360  Accept-Ranges: none
363   to advise the client not to attempt a range request.
369<section title="Range Requests" anchor="range.requests">
[2142]370<section title="Range" anchor="header.range">
371  <iref primary="true" item="Range header field" x:for-anchor=""/>
372  <x:anchor-alias value="Range"/>
373  <x:anchor-alias value="other-ranges-specifier"/>
374  <x:anchor-alias value="other-range-set"/>
376   The "Range" header field on a GET request modifies the method semantics to
[2150]377   request transfer of only one or more subranges of the selected
378   representation data, rather than the entire selected representation data.
380<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="Range"/>
381  <x:ref>Range</x:ref> = <x:ref>byte-ranges-specifier</x:ref> / <x:ref>other-ranges-specifier</x:ref>
382  <x:ref>other-ranges-specifier</x:ref> = <x:ref>other-range-unit</x:ref> "=" <x:ref>other-range-set</x:ref>
383  <x:ref>other-range-set</x:ref> = 1*<x:ref>CHAR</x:ref>
386   A server &MAY; ignore the Range header field. However, origin servers and
387   intermediate caches ought to support byte ranges when possible, since Range
388   supports efficient recovery from partially failed transfers and partial
389   retrieval of large representations. A server &MUST; ignore a Range header
390   field received with a request method other than GET.
[2150]393   An origin server &MUST; ignore a Range header field that contains a range
394   unit it does not understand. A proxy &MAY; either discard a Range header
395   field that contains a range unit it does not understand or pass it to the
396   next inbound server when forwarding the request.
[2157]399   A server that supports range requests ought to ignore or reject a
400   <x:ref>Range</x:ref> header field that consists of more than two
401   overlapping ranges, or a set of many small ranges that are not listed
402   in ascending order, since both are indications of either a broken client or
403   a deliberate denial of service attack (<xref target="overlapping.ranges"/>).
404   A client &SHOULD-NOT; request multiple ranges that are inherently less
405   efficient to process and transfer than a single range that encompasses the
406   same data.
409   A client that is requesting multiple ranges &SHOULD; list those ranges in
410   ascending order (the order in which they would typically be received in a
411   complete representation) unless there is a specific need to request a later
412   part earlier. For example, a user agent processing a large representation
413   with an internal catalog of parts might need to request later parts first,
414   particularly if the representation consists of pages stored in reverse
415   order and the user agent wishes to transfer one page at a time.
[2299]418   The Range header field is evaluated after evaluating the precondition header
419   fields defined in <xref target="Part4"/>, and only if the result in absence
420   of the Range header field would be a <x:ref>200 (OK)</x:ref> response. In
421   other words, Range is ignored when a conditional GET would result in a
[2142]422   <x:ref>304 (Not Modified)</x:ref> response.
425   The If-Range header field (<xref target="header.if-range"/>) can be used as
426   a precondition to applying the Range header field.
429   If all of the preconditions are true, the server supports the Range header
[2150]430   field for the target resource, and the specified range(s) are valid and
431   satisfiable (as defined in <xref target="byte.ranges"/>), the
432   server &SHOULD; send a <x:ref>206 (Partial Content)</x:ref> response with a
433   payload containing one or more partial representations that correspond to
434   the satisfiable ranges requested, as defined in
[2142]435   <xref target="range.response"/>.
438   If all of the preconditions are true, the server supports the Range header
439   field for the target resource, and the specified range(s) are invalid or
440   unsatisfiable, the server &SHOULD; send a
441   <x:ref>416 (Range Not Satisfiable)</x:ref> response.
[2142]445<section title="If-Range" anchor="header.if-range">
446  <iref primary="true" item="If-Range header field" x:for-anchor=""/>
447  <x:anchor-alias value="If-Range"/>
449   If a client has a partial copy of a representation and wishes
450   to have an up-to-date copy of the entire representation, it could use the
451   <x:ref>Range</x:ref> header field with a conditional GET (using
452   either or both of <x:ref>If-Unmodified-Since</x:ref> and
453   <x:ref>If-Match</x:ref>.) However, if the condition fails because the
454   representation has been modified, the client would then have to make a
455   second request to obtain the entire current representation.
458   The "If-Range" header field allows a client to "short-circuit" the second
459   request. Informally, its meaning is: if the representation is unchanged,
460   send me the part(s) that I am requesting in Range; otherwise, send me the
461   entire representation.
463<figure><artwork type="abnf2616"><iref primary="true" item="Grammar" subitem="If-Range"/>
464  <x:ref>If-Range</x:ref> = <x:ref>entity-tag</x:ref> / <x:ref>HTTP-date</x:ref>
[2292]467   A client &MUST-NOT; generate an If-Range header field containing an
468   entity-tag that is marked as weak.
469   A client &MUST-NOT; generate an If-Range header field containing a
470   <x:ref>Last-Modified</x:ref> date unless the client has no entity-tag for
471   the corresponding representation and the Last-Modified date is strong
[2142]472   in the sense defined by &lastmod-comparison;.
475   A server that evaluates a conditional range request that is applicable
476   to one of its representations &MUST; evaluate the condition as false if
477   the entity-tag used as a validator is marked as weak or, when an HTTP-date
478   is used as the validator, if the date value is not strong in the sense
479   defined by &lastmod-comparison;. (A server can distinguish between a
480   valid HTTP-date and any form of entity-tag by examining the first
481   two characters.)
[2150]484   A client &MUST-NOT; generate an If-Range header field in a request that
485   does not contain a <x:ref>Range</x:ref> header field.
486   A server &MUST; ignore an If-Range header field received in a request that
487   does not contain a <x:ref>Range</x:ref> header field.
488   An origin server &MUST; ignore an If-Range header field received in a
489   request for a target resource that does not support Range requests.
492   If the validator given in the If-Range header field matches the current
493   validator for the selected representation of the target resource, then
[2150]494   the server &SHOULD; process the Range header field as requested.
495   If the validator does not match, then the server &MUST; ignore the
496   <x:ref>Range</x:ref> header field.
[2143]502<section title="Responses to a Range Request" anchor="range.response">
504<section title="206 Partial Content" anchor="status.206">
505  <iref primary="true" item="206 Partial Content (status code)" x:for-anchor=""/>
506  <x:anchor-alias value="206"/>
507  <x:anchor-alias value="206 (Partial Content)"/>
[2152]509   The <x:dfn>206 (Partial Content)</x:dfn> status code indicates that the
[2153]510   server is successfully fulfilling a range request for the target resource
511   by transferring one or more parts of the selected representation that
[2196]512   correspond to the satisfiable ranges found in the request's
[2153]513   <x:ref>Range</x:ref> header field (<xref target="header.range"/>).
[2153]516   If a single part is being transferred, the server generating the 206
517   response &MUST; generate a <x:ref>Content-Range</x:ref> header field,
518   describing what range of the selected representation is enclosed, and a
519   payload consisting of the range. For example:
521<figure><artwork type="message/http; msgtype=&#34;response&#34;" x:indent-with="  ">
522HTTP/1.1 206 Partial Content
523Date: Wed, 15 Nov 1995 06:25:24 GMT
524Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
525Content-Range: bytes 21010-47021/47022
526Content-Length: 26012
527Content-Type: image/gif
[2157]529... 26012 bytes of partial image data ...
[2153]532   If multiple parts are being transferred, the server generating the 206
533   response &MUST; generate a "multipart/byteranges" payload, as defined
[2158]534   in <xref target=""/>, and a
[2153]535   <x:ref>Content-Type</x:ref> header field containing the
[2157]536   multipart/byteranges media type and its required boundary parameter.
[2158]537   To avoid confusion with single part responses, a server &MUST-NOT; generate
538   a <x:ref>Content-Range</x:ref> header field in the HTTP header block of a
539   multiple part response (this field will be sent in each part instead).
[2157]542   Within the header area of each body part in the multipart payload, the
543   server &MUST; generate a <x:ref>Content-Range</x:ref> header field
544   corresponding to the range being enclosed in that body part.
545   If the selected representation would have had a <x:ref>Content-Type</x:ref>
546   header field in a <x:ref>200 (OK)</x:ref> response, the server &SHOULD;
547   generate that same <x:ref>Content-Type</x:ref> field in the header area of
548   each body part. For example:
[2157]550<figure><artwork type="message/http; msgtype=&#34;response&#34;" x:indent-with="  ">
[2153]551HTTP/1.1 206 Partial Content
552Date: Wed, 15 Nov 1995 06:25:24 GMT
553Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
554Content-Length: 1741
555Content-Type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
558Content-Type: application/pdf
559Content-Range: bytes 500-999/8000
561...the first range...
563Content-Type: application/pdf
564Content-Range: bytes 7000-7999/8000
566...the second range
[2157]570   When multiple ranges are requested, a server &MAY; coalesce any of the
571   ranges that overlap or that are separated by a gap that is smaller than the
572   overhead of sending multiple parts, regardless of the order in which the
573   corresponding byte-range-spec appeared in the received <x:ref>Range</x:ref>
574   header field. Since the typical overhead between parts of a
575   multipart/byteranges payload is around 80 bytes, depending on the selected
576   representation's media type and the chosen boundary parameter length, it
577   can be less efficient to transfer many small disjoint parts than it is to
578   transfer the entire selected representation.
[2157]581   A server &MUST-NOT; generate a multipart response to a request for a single
582   range, since a client that does not request multiple parts might not
583   support multipart responses. However, a server &MAY; generate a
584   multipart/byteranges payload with only a single body part if multiple
585   ranges were requested and only one range was found to be satisfiable or
586   only one range remained after coalescing.
[2290]587   A client that cannot process a multipart/byteranges response &MUST-NOT; 
[2292]588   generate a request that asks for multiple ranges.
[2157]591   When a multipart response payload is generated, the server &SHOULD; send
592   the parts in the same order that the corresponding byte-range-spec appeared
593   in the received <x:ref>Range</x:ref> header field, excluding those ranges
594   that were deemed unsatisfiable or that were coalesced into other ranges.
595   A client that receives a multipart response &MUST; inspect the
596   <x:ref>Content-Range</x:ref> header field present in each body part in
597   order to determine which range is contained in that body part; a client
598   cannot rely on receiving the same ranges that it requested, nor the same
599   order that it requested.
[2157]602   When a 206 response is generated, the server &MUST; generate the following
[2158]603   header fields, in addition to those required above, if the field would
[2157]604   have been sent in a <x:ref>200 (OK)</x:ref> response to the same request:
605   <x:ref>Date</x:ref>, <x:ref>Cache-Control</x:ref>, <x:ref>ETag</x:ref>,
606   <x:ref>Expires</x:ref>, <x:ref>Content-Location</x:ref>, and
607   <x:ref>Vary</x:ref>.
[2066]610   If a 206 is generated in response to a request with an <x:ref>If-Range</x:ref>
611   header field, the sender &SHOULD-NOT; generate other representation header
[2158]612   fields beyond those required above, because the client is understood to
[2157]613   already have a prior response containing those header fields.
614   Otherwise, the sender &MUST; generate all of the representation header
[2066]615   fields that would have been sent in a <x:ref>200 (OK)</x:ref> response
[1738]616   to the same request.
[2166]619   A 206 response is cacheable unless otherwise indicated by
620   explicit cache controls (see &p6-heuristic;).
624<section title="Content-Range" anchor="header.content-range">
[1120]625  <iref primary="true" item="Content-Range header field" x:for-anchor=""/>
[229]626  <x:anchor-alias value="Content-Range"/>
[2135]627  <x:anchor-alias value="byte-content-range"/>
628  <x:anchor-alias value="byte-range-resp"/>
629  <x:anchor-alias value="byte-range"/>
630  <x:anchor-alias value="unsatisfied-range"/>
631  <x:anchor-alias value="complete-length"/>
632  <x:anchor-alias value="other-content-range"/>
633  <x:anchor-alias value="other-range-resp"/>
[2158]635   The "Content-Range" header field is sent in a single part
636   <x:ref>206 (Partial Content)</x:ref> response to indicate the partial range
637   of the selected representation enclosed as the message payload, sent in
638   each part of a multipart 206 response to indicate the range enclosed within
639   each body part, and sent in <x:ref>416 (Range Not Satisfiable)</x:ref>
640   responses to provide information about the selected representation.
[2135]642<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"/>
643  <x:ref>Content-Range</x:ref>       = <x:ref>byte-content-range</x:ref>
644                      / <x:ref>other-content-range</x:ref>
[2135]646  <x:ref>byte-content-range</x:ref>  = <x:ref>bytes-unit</x:ref> <x:ref>SP</x:ref>
[2138]647                        ( <x:ref>byte-range-resp</x:ref> / <x:ref>unsatisfied-range</x:ref> )
649  <x:ref>byte-range-resp</x:ref>     = <x:ref>byte-range</x:ref> "/" ( <x:ref>complete-length</x:ref> / "*" )
650  <x:ref>byte-range</x:ref>          = <x:ref>first-byte-pos</x:ref> "-" <x:ref>last-byte-pos</x:ref>
651  <x:ref>unsatisfied-range</x:ref>   = "*/" <x:ref>complete-length</x:ref>
[2135]653  <x:ref>complete-length</x:ref>     = 1*<x:ref>DIGIT</x:ref>
[2135]655  <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>
656  <x:ref>other-range-resp</x:ref>    = *<x:ref>CHAR</x:ref>
[2158]659   If a <x:ref>206 (Partial Content)</x:ref> response contains a
[2135]660   <x:ref>Content-Range</x:ref> header field with a <x:ref>range unit</x:ref>
[2158]661   (<xref target="range.units"/>) that the recipient does not understand, the
662   recipient &MUST-NOT; attempt to recombine it with a stored representation.
663   A proxy that receives such a message &SHOULD; forward it downstream.
[2135]666   For byte ranges, a sender &SHOULD; indicate the complete length of the
[2158]667   representation from which the range has been extracted, unless the complete
[2135]668   length is unknown or difficult to determine. An asterisk character ("*") in
669   place of the complete-length indicates that the representation length was
670   unknown when the header field was generated.
[2158]673   The following example illustrates when the complete length of the selected
674   representation is known by the sender to be 1234 bytes:
[2135]676<figure><artwork type="example">
677  Content-Range: bytes 42-1233/1234
[2158]680   and this second example illustrates when the complete length is unknown:
[2135]682<figure><artwork type="example">
683  Content-Range: bytes 42-1233/*
[2158]686   A Content-Range field value is invalid if it contains a
687   <x:ref>byte-range-resp</x:ref> that has a <x:ref>last-byte-pos</x:ref>
688   value less than its <x:ref>first-byte-pos</x:ref> value, or a
689   <x:ref>complete-length</x:ref> value less than or equal to its
690   <x:ref>last-byte-pos</x:ref> value. The recipient of an invalid
691   <x:ref>Content-Range</x:ref> &MUST-NOT; attempt to recombine the received
692   content with a stored representation.
[2135]695   A server generating a <x:ref>416 (Range Not Satisfiable)</x:ref> response
696   to a byte range request &SHOULD; send a Content-Range header field with an
697   <x:ref>unsatisfied-range</x:ref> value, as in the following example:
[2135]699<figure><artwork type="example">
700  Content-Range: bytes */1234
[2135]703   The complete-length in a 416 response indicates the current length of the
[2158]704   selected representation.
707   The "Content-Range" header field has no meaning for status codes that do
708   not explicitly describe its semantic. For this specification, only the
709   <x:ref>206 (Partial Content)</x:ref> and
710   <x:ref>416 (Range Not Satisfiable)</x:ref> status codes describe a meaning
711   for Content-Range.
[2158]714   The following are examples of Content-Range values in which the
715   selected representation contains a total of 1234 bytes:
[8]716   <list style="symbols">
717      <t>
718        The first 500 bytes:
[565]719<figure><artwork type="example" x:indent-with="   ">
[2135]720  Content-Range: bytes 0-499/1234
722      </t>   
723      <t>
724        The second 500 bytes:
[565]725<figure><artwork type="example" x:indent-with="   ">
[2135]726  Content-Range: bytes 500-999/1234
728      </t>   
729      <t>
730        All except for the first 500 bytes:
[565]731<figure><artwork type="example" x:indent-with="   ">
[2135]732  Content-Range: bytes 500-1233/1234
734      </t>   
735      <t>
736        The last 500 bytes:
[565]737<figure><artwork type="example" x:indent-with="   ">
[2135]738  Content-Range: bytes 734-1233/1234
740      </t>   
741   </list>
[2142]745<section title="Combining Ranges" anchor="combining.byte.ranges">
[2142]747   A response might transfer only a subrange of a representation if the
748   connection closed prematurely or if the request used one or more Range
749   specifications.  After several such transfers, a client might have
750   received several ranges of the same representation.  These ranges can only
751   be safely combined if they all have in common the same strong validator,
752   where "strong validator" is defined to be either an entity-tag that is
753   not marked as weak (&entity-tags;) or, if no entity-tag is provided, a
754   <x:ref>Last-Modified</x:ref> value that is strong in the sense defined by
755   &lastmod-comparison;.
[2158]758   A client that has received multiple partial responses to GET requests on a
759   target resource &MAY; combine those responses into a larger continuous
760   range if they share the same strong validator.
[2158]763   If the most recent response is an incomplete <x:ref>200 (OK)</x:ref>
764   response, then the header fields of that response are used for any
765   combined response and replace those of the matching stored responses.
[2158]768   If the most recent response is a <x:ref>206 (Partial Content)</x:ref>
769   response and at least one of the matching stored responses is a
770   <x:ref>200 (OK)</x:ref>, then the combined response header fields consist
771   of the most recent 200 response's header fields. If all of the matching
772   stored responses are 206 responses, then the stored response with the most
773   recent header fields is used as the source of header fields for the
774   combined response, except that the client &MUST; use other header fields
775   provided in the new response, aside from <x:ref>Content-Range</x:ref>, to
776   replace all instances of the corresponding header fields in the stored
777   response.
[2142]780   The combined response message body consists of the union of partial
781   content ranges in the new response and each of the selected responses.
782   If the union consists of the entire range of the representation, then the
[2297]783   client &MUST; process the combined response as if it were a complete
[2142]784   <x:ref>200 (OK)</x:ref> response, including a <x:ref>Content-Length</x:ref>
785   header field that reflects the complete length.
[2297]786   Otherwise, the client &MUST; process the set of continuous ranges as one of
[2142]787   the following:
788   an incomplete <x:ref>200 (OK)</x:ref> response if the combined response is
789   a prefix of the representation,
790   a single <x:ref>206 (Partial Content)</x:ref> response containing a
791   multipart/byteranges body, or
792   multiple <x:ref>206 (Partial Content)</x:ref> responses, each with one
793   continuous range that is indicated by a <x:ref>Content-Range</x:ref> header
794   field.
798<section title="416 Range Not Satisfiable" anchor="status.416">
799  <iref primary="true" item="416 Range Not Satisfiable (status code)" x:for-anchor=""/>
800  <x:anchor-alias value="416 (Range Not Satisfiable)"/>
[2158]802   The <x:dfn>416 (Range Not Satisfiable)</x:dfn> status code indicates that
803   none of the ranges in the request's <x:ref>Range</x:ref> header field
804   (<xref target="header.range"/>) overlap the current extent of the selected
805   resource or that the set of ranges requested has been rejected due to
806   invalid ranges or an excessive request of small or overlapping ranges.
[2158]809   For byte ranges, failing to overlap the current extent means that the
810   <x:ref>first-byte-pos</x:ref> of all of the <x:ref>byte-range-spec</x:ref>
811   values were greater than the current length of the selected representation.
812   When this status code is generated in response to a byte range request, the
[2152]813   sender &SHOULD; generate a <x:ref>Content-Range</x:ref> header field
814   specifying the current length of the selected representation
[2158]815   (<xref target="header.content-range"/>).
818<preamble>For example:</preamble>
819<artwork type="message/http; msgtype=&#34;response&#34;" x:indent-with="  ">
820HTTP/1.1 416 Range Not Satisfiable
[2207]821Date: Fri, 20 Jan 2012 15:41:54 GMT
[2152]822Content-Range: bytes */47022
825  <t>
[2158]826    &Note; Because servers are free to ignore <x:ref>Range</x:ref>, many
[2217]827    implementations will simply respond with the entire selected representation
[2297]828    in a <x:ref>200 (OK)</x:ref> response. That is partly because
[2158]829    most clients are prepared to receive a <x:ref>200 (OK)</x:ref> to
830    complete the task (albeit less efficiently) and partly because clients
831    might not stop making an invalid partial request until they have received
832    a complete representation. Thus, clients cannot depend on receiving a
833    <x:ref>416 (Range Not Satisfiable)</x:ref> response even when it is most
834    appropriate.
[2152]835  </t>
[29]840<section title="IANA Considerations" anchor="IANA.considerations">
[2139]842<section title="Range Unit Registry" anchor="range.unit.registry">
844   The HTTP Range Unit Registry defines the name space for the range
845   unit names and refers to their corresponding specifications.
[2246]846   The registry will be created and maintained at
[2151]847   <eref target=""/>.
850<section title="Procedure" anchor="range.unit.registry.procedure">
852   Registration of an HTTP Range Unit &MUST; include the following fields:
853   <list style="symbols">
854     <t>Name</t>
855     <t>Description</t>
856     <t>Pointer to specification text</t>
857   </list>
860  Values to be added to this name space require IETF Review
861  (see <xref target="RFC5226" x:fmt="," x:sec="4.1"/>).
865<section title="Registrations" anchor="range.unit.registration">
867   The initial HTTP Range Unit Registry shall contain the registrations
868   below:
870<texttable align="left" suppress-title="true" anchor="iana.range.units.table">
[2153]871   <ttcol>Range Unit Name</ttcol>
[2139]872   <ttcol>Description</ttcol>
873   <ttcol>Reference</ttcol>
875   <c>bytes</c>
876   <c>a range of octets</c>
[2144]877   <c><xref target="byte.ranges"/></c>
879   <c>none</c>
880   <c>reserved as keyword, indicating no ranges are supported</c>
881   <c><xref target="header.accept-ranges"/></c>
884   The change controller is: "IETF ( - Internet Engineering Task Force".
[700]889<section title="Status Code Registration" anchor="status.code.registration">
891   The HTTP Status Code Registry located at <eref target=""/>
[969]892   shall be updated with the registrations below:
894<?BEGININC p5-range.iana-status-codes ?>
895<!--AUTOGENERATED FROM extract-status-code-defs.xslt, do not edit manually-->
896<texttable align="left" suppress-title="true" anchor="iana.status.code.registration.table">
897   <ttcol>Value</ttcol>
898   <ttcol>Description</ttcol>
899   <ttcol>Reference</ttcol>
900   <c>206</c>
901   <c>Partial Content</c>
902   <c>
903      <xref target="status.206"/>
904   </c>
905   <c>416</c>
[2121]906   <c>Range Not Satisfiable</c>
[700]907   <c>
908      <xref target="status.416"/>
909   </c>
912<?ENDINC p5-range.iana-status-codes ?>
[921]915<section title="Header Field Registration" anchor="header.field.registration">
[2246]917   HTTP header fields are registered within the Message Header Field Registry
918   maintained at
919   <eref target=""/>.
922   This document defines the following HTTP header fields, so their
923   associated registry entries shall be updated according to the permanent
924   registrations below (see <xref target="BCP90"/>):
[680]926<?BEGININC p5-range.iana-headers ?>
[253]927<!--AUTOGENERATED FROM extract-header-defs.xslt, do not edit manually-->
[290]928<texttable align="left" suppress-title="true" anchor="iana.header.registration.table">
[253]929   <ttcol>Header Field Name</ttcol>
930   <ttcol>Protocol</ttcol>
931   <ttcol>Status</ttcol>
932   <ttcol>Reference</ttcol>
934   <c>Accept-Ranges</c>
935   <c>http</c>
936   <c>standard</c>
937   <c>
938      <xref target="header.accept-ranges"/>
939   </c>
940   <c>Content-Range</c>
941   <c>http</c>
942   <c>standard</c>
943   <c>
944      <xref target="header.content-range"/>
945   </c>
946   <c>If-Range</c>
947   <c>http</c>
948   <c>standard</c>
949   <c>
950      <xref target="header.if-range"/>
951   </c>
952   <c>Range</c>
953   <c>http</c>
954   <c>standard</c>
955   <c>
956      <xref target="header.range"/>
957   </c>
[680]960<?ENDINC p5-range.iana-headers ?>
[290]962   The change controller is: "IETF ( - Internet Engineering Task Force".
968<section title="Security Considerations" anchor="security.considerations">
[2069]970   This section is meant to inform developers, information providers, and
971   users of known security concerns specific to the HTTP/1.1 range
972   request mechanisms. More general security considerations are addressed
973   in HTTP messaging &messaging; and semantics &semantics;.
[2157]976<section title="Denial of Service Attacks using Range" anchor="overlapping.ranges">
[2157]978   Unconstrained multiple range requests are susceptible to denial of service
979   attacks because the effort required to request many overlapping ranges of
980   the same data is tiny compared to the time, memory, and bandwidth consumed
981   by attempting to serve the requested data in many parts.
982   Servers ought to ignore, coalesce, or reject egregious range requests, such
983   as requests for more than two overlapping ranges or for many small ranges
984   in a single set, particularly when the ranges are requested out of order
985   for no apparent reason. Multipart range requests are not designed to
986   support random access.
[1364]991<section title="Acknowledgments" anchor="acks">
[1364]993  See &acks;.
[119]999<references title="Normative References">
[31]1001<reference anchor="Part1">
[119]1002  <front>
[1864]1003    <title>Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing</title>
[119]1004    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
[1106]1005      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[119]1006      <address><email></email></address>
1007    </author>
1008    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1009      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1010      <address><email></email></address>
1011    </author>
1012    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1013  </front>
1014  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p1-messaging-&ID-VERSION;"/>
[1740]1015  <x:source href="p1-messaging.xml" basename="p1-messaging">
1016    <x:defines>Content-Length</x:defines>
1017  </x:source>
[1436]1020<reference anchor="Part2">
1021  <front>
[1864]1022    <title>Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content</title>
[1436]1023    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
1024      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1025      <address><email></email></address>
1026    </author>
1027    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1028      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1029      <address><email></email></address>
1030    </author>
1031    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1032  </front>
1033  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p2-semantics-&ID-VERSION;"/>
[1715]1034  <x:source href="p2-semantics.xml" basename="p2-semantics">
1035    <x:defines>200 (OK)</x:defines>
[1735]1036    <x:defines>410 (Gone)</x:defines>
[1740]1037    <x:defines>Content-Location</x:defines>
1038    <x:defines>Content-Type</x:defines>
[2152]1039    <x:defines>Date</x:defines>
[1740]1040    <x:defines>Location</x:defines>
[1860]1041    <x:defines>Vary</x:defines>
[1715]1042  </x:source>
[31]1045<reference anchor="Part4">
[119]1046  <front>
[1864]1047    <title>Hypertext Transfer Protocol (HTTP/1.1): Conditional Requests</title>
[119]1048    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
[1106]1049      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
[119]1050      <address><email></email></address>
1051    </author>
1052    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1053      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1054      <address><email></email></address>
1055    </author>
1056    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1057  </front>
1058  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p4-conditional-&ID-VERSION;"/>
[1734]1059  <x:source href="p4-conditional.xml" basename="p4-conditional">
1060    <x:defines>304 (Not Modified)</x:defines>
[1739]1061    <x:defines>ETag</x:defines>
1062    <x:defines>If-Match</x:defines>
1063    <x:defines>If-Modified-Since</x:defines>
1064    <x:defines>If-None-Match</x:defines>
1065    <x:defines>If-Unmodified-Since</x:defines>
1066    <x:defines>Last-Modified</x:defines>
[1734]1067  </x:source>
[1524]1070<reference anchor="Part6">
1071  <front>
[1864]1072    <title>Hypertext Transfer Protocol (HTTP/1.1): Caching</title>
[1524]1073    <author initials="R." surname="Fielding" fullname="Roy T. Fielding" role="editor">
1074      <organization abbrev="Adobe">Adobe Systems Incorporated</organization>
1075      <address><email></email></address>
1076    </author>
1077    <author initials="M." surname="Nottingham" fullname="Mark Nottingham" role="editor">
[1915]1078      <organization>Akamai</organization>
[1524]1079      <address><email></email></address>
1080    </author>
1081    <author initials="J. F." surname="Reschke" fullname="Julian F. Reschke" role="editor">
1082      <organization abbrev="greenbytes">greenbytes GmbH</organization>
1083      <address><email></email></address>
1084    </author>
1085    <date month="&ID-MONTH;" year="&ID-YEAR;"/>
1086  </front>
1087  <seriesInfo name="Internet-Draft" value="draft-ietf-httpbis-p6-cache-&ID-VERSION;"/>
[1737]1088  <x:source href="p6-cache.xml" basename="p6-cache">
[1739]1089    <x:defines>Cache-Control</x:defines>
[1737]1090    <x:defines>Expires</x:defines>
1091  </x:source>
[131]1094<reference anchor="RFC2046">
1095  <front>
1096    <title abbrev="Media Types">Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types</title>
1097    <author initials="N." surname="Freed" fullname="Ned Freed">
1098      <organization>Innosoft International, Inc.</organization>
1099      <address><email></email></address>
1100    </author>
1101    <author initials="N." surname="Borenstein" fullname="Nathaniel S. Borenstein">
1102      <organization>First Virtual Holdings</organization>
1103      <address><email></email></address>
1104    </author>
1105    <date month="November" year="1996"/>
1106  </front>
1107  <seriesInfo name="RFC" value="2046"/>
[119]1110<reference anchor="RFC2119">
1111  <front>
1112    <title>Key words for use in RFCs to Indicate Requirement Levels</title>
1113    <author initials="S." surname="Bradner" fullname="Scott Bradner">
1114      <organization>Harvard University</organization>
1115      <address><email></email></address>
1116    </author>
1117    <date month="March" year="1997"/>
1118  </front>
1119  <seriesInfo name="BCP" value="14"/>
1120  <seriesInfo name="RFC" value="2119"/>
[425]1123<reference anchor="RFC5234">
1124  <front>
1125    <title abbrev="ABNF for Syntax Specifications">Augmented BNF for Syntax Specifications: ABNF</title>
1126    <author initials="D." surname="Crocker" fullname="Dave Crocker" role="editor">
1127      <organization>Brandenburg InternetWorking</organization>
1128      <address>
[728]1129        <email></email>
1130      </address> 
[425]1131    </author>
1132    <author initials="P." surname="Overell" fullname="Paul Overell">
1133      <organization>THUS plc.</organization>
1134      <address>
[728]1135        <email></email>
1136      </address>
[425]1137    </author>
1138    <date month="January" year="2008"/>
1139  </front>
1140  <seriesInfo name="STD" value="68"/>
1141  <seriesInfo name="RFC" value="5234"/>
1146<references title="Informative References">
[36]1148<reference anchor="RFC2616">
[119]1149  <front>
1150    <title>Hypertext Transfer Protocol -- HTTP/1.1</title>
1151    <author initials="R." surname="Fielding" fullname="R. Fielding">
1152      <organization>University of California, Irvine</organization>
1153      <address><email></email></address>
1154    </author>
1155    <author initials="J." surname="Gettys" fullname="J. Gettys">
1156      <organization>W3C</organization>
1157      <address><email></email></address>
1158    </author>
1159    <author initials="J." surname="Mogul" fullname="J. Mogul">
1160      <organization>Compaq Computer Corporation</organization>
1161      <address><email></email></address>
1162    </author>
1163    <author initials="H." surname="Frystyk" fullname="H. Frystyk">
1164      <organization>MIT Laboratory for Computer Science</organization>
1165      <address><email></email></address>
1166    </author>
1167    <author initials="L." surname="Masinter" fullname="L. Masinter">
1168      <organization>Xerox Corporation</organization>
1169      <address><email></email></address>
1170    </author>
1171    <author initials="P." surname="Leach" fullname="P. Leach">
1172      <organization>Microsoft Corporation</organization>
1173      <address><email></email></address>
1174    </author>
1175    <author initials="T." surname="Berners-Lee" fullname="T. Berners-Lee">
1176      <organization>W3C</organization>
1177      <address><email></email></address>
1178    </author>
1179    <date month="June" year="1999"/>
1180  </front>
1181  <seriesInfo name="RFC" value="2616"/>
[2046]1184<reference anchor='BCP90'>
[253]1185  <front>
1186    <title>Registration Procedures for Message Header Fields</title>
1187    <author initials='G.' surname='Klyne' fullname='G. Klyne'>
1188      <organization>Nine by Nine</organization>
1189      <address><email></email></address>
1190    </author>
1191    <author initials='M.' surname='Nottingham' fullname='M. Nottingham'>
1192      <organization>BEA Systems</organization>
1193      <address><email></email></address>
1194    </author>
1195    <author initials='J.' surname='Mogul' fullname='J. Mogul'>
1196      <organization>HP Labs</organization>
1197      <address><email></email></address>
1198    </author>
1199    <date year='2004' month='September' />
1200  </front>
1201  <seriesInfo name='BCP' value='90' />
1202  <seriesInfo name='RFC' value='3864' />
[2046]1205<reference anchor="BCP13">
[196]1206  <front>
1207    <title>Media Type Specifications and Registration Procedures</title>
[2170]1208    <author initials="N." surname="Freed" fullname="Ned Freed">
1209      <organization>Oracle</organization>
[196]1210      <address>
[2170]1211        <email></email>
[196]1212      </address>
1213    </author>
[2170]1214    <author initials="J." surname="Klensin" fullname="John C. Klensin">
[196]1215      <address>
[2170]1216        <email></email>
[196]1217      </address>
1218    </author>
[2170]1219    <author initials="T." surname="Hansen" fullname="Tony Hansen">
1220      <organization>AT&amp;T Laboratories</organization>
1221      <address>
1222        <email></email>
1223      </address>
1224    </author>
1225    <date year="2013" month="January"/>
[196]1226  </front>
1227  <seriesInfo name="BCP" value="13"/>
[2170]1228  <seriesInfo name="RFC" value="6838"/>
[930]1231<reference anchor='RFC5226'>
1232  <front>
1233    <title>Guidelines for Writing an IANA Considerations Section in RFCs</title>
1234    <author initials='T.' surname='Narten' fullname='T. Narten'>
1235      <organization>IBM</organization>
1236      <address><email></email></address>
1237    </author>
1238    <author initials='H.' surname='Alvestrand' fullname='H. Alvestrand'>
1239      <organization>Google</organization>
1240      <address><email></email></address>
1241    </author>
1242    <date year='2008' month='May' />
1243  </front>
1244  <seriesInfo name='BCP' value='26' />
1245  <seriesInfo name='RFC' value='5226' />
[8]1250<section title="Internet Media Type multipart/byteranges" anchor="">
1251<iref item="Media Type" subitem="multipart/byteranges" primary="true"/>
1252<iref item="multipart/byteranges Media Type" primary="true"/>
[2153]1254   When a <x:ref>206 (Partial Content)</x:ref> response message includes the
[2157]1255   content of multiple ranges, they are transmitted as body parts in a
[2153]1256   multipart message body (<xref target="RFC2046" x:fmt="," x:sec="5.1"/>)
1257   with the media type of "multipart/byteranges".  The following definition is
1258   to be registered with IANA <xref target="BCP13"/>.
[2157]1261   The multipart/byteranges media type includes one or more body parts, each
[1740]1262   with its own <x:ref>Content-Type</x:ref> and <x:ref>Content-Range</x:ref>
1263   fields. The required boundary parameter specifies the boundary string used
[2157]1264   to separate each body part.
1267  <list style="hanging" x:indent="12em">
[196]1268    <t hangText="Type name:">
[8]1269      multipart
1270    </t>
[196]1271    <t hangText="Subtype name:">
[8]1272      byteranges
1273    </t>
1274    <t hangText="Required parameters:">
1275      boundary
1276    </t>
1277    <t hangText="Optional parameters:">
1278      none
1279    </t>
1280    <t hangText="Encoding considerations:">
1281      only "7bit", "8bit", or "binary" are permitted
1282    </t>
1283    <t hangText="Security considerations:">
1284      none
1285    </t>
[196]1286    <t hangText="Interoperability considerations:">
1287      none
1288    </t>
1289    <t hangText="Published specification:">
1290      This specification (see <xref target=""/>).
1291    </t>
1292    <t hangText="Applications that use this media type:">
[1749]1293      HTTP components supporting multiple ranges in a single request.
[196]1294    </t>
1295    <t hangText="Additional information:">
1296      <list style="hanging">
1297        <t hangText="Magic number(s):">none</t>
1298        <t hangText="File extension(s):">none</t>
1299        <t hangText="Macintosh file type code(s):">none</t>
1300      </list>
1301    </t>
1302    <t hangText="Person and email address to contact for further information:">
1303      See Authors Section.
1304    </t>
[609]1305    <t hangText="Intended usage:">
1306      COMMON
[196]1307    </t>
[609]1308    <t hangText="Restrictions on usage:">
1309      none
[196]1310    </t>
[2208]1311    <t hangText="Author:">
1312      See Authors Section.
1313    </t>
1314    <t hangText="Change controller:">
[196]1315      IESG
1316    </t>
[8]1317  </list>
[2153]1320  Implementation Notes:
[8]1321  <list style="numbers">
[2153]1322      <t>Additional CRLFs might precede the first boundary string in the body.</t>
[97]1324      <t>Although <xref target="RFC2046"/> permits the boundary string to be
[8]1325         quoted, some existing implementations handle a quoted boundary
1326         string incorrectly.</t>
[1600]1328      <t>A number of clients and servers were coded to an early draft
[2153]1329         of the byteranges specification that used a media type of
1330         multipart/x-byteranges<iref item="multipart/x-byteranges Media Type"/><iref item="Media Type" subitem="multipart/x-byteranges"/>,
1331         which is almost (but not quite) compatible with this type.</t>
[8]1332  </list>
1335   Despite the name, the "multipart/byteranges" media type is not limited to
1336   byte ranges. The following example uses an "exampleunit" range unit:
1338<figure><artwork type="message/http; msgtype=&#34;response&#34;" x:indent-with="  ">
1339HTTP/1.1 206 Partial Content
1340Date: Tue, 14 Nov 1995 06:25:24 GMT
1341Last-Modified: Tue, 14 July 04:58:08 GMT
1342Content-Length: 2331785
1343Content-Type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
1346Content-Type: video/example
1347Content-Range: exampleunit 1.2-4.3/25
1349...the first range...
1351Content-Type: video/example
1352Content-Range: exampleunit 11.2-14.3/25
1354...the second range
[99]1360<section title="Changes from RFC 2616" anchor="changes.from.rfc.2616">
[2015]1363  A weak validator cannot be used in a <x:ref>206</x:ref> response.
[105]1364  (<xref target="status.206"/>)
[2021]1367  The Content-Range header field only has meaning when the status code
1368  explicitly defines its use.
1369  (<xref target="header.content-range" />)
[2053]1372  Servers are given more leeway in how they respond to a range request,
1373  in order to mitigate abuse by malicious (or just greedy) clients.
[2015]1376  multipart/byteranges can consist of a single part.
[332]1377  (<xref target=""/>)
[2153]1380  This specification introduces a Range Unit Registry.
[2135]1381  (<xref target="range.unit.registry"/>)
[1805]1385<section title="Imported ABNF" anchor="imported.abnf">
1386  <x:anchor-alias value="ALPHA"/>
1387  <x:anchor-alias value="CHAR"/>
1388  <x:anchor-alias value="CR"/>
1389  <x:anchor-alias value="DIGIT"/>
1390  <x:anchor-alias value="LF"/>
1391  <x:anchor-alias value="OCTET"/>
1392  <x:anchor-alias value="SP"/>
1393  <x:anchor-alias value="VCHAR"/>
1394  <x:anchor-alias value="token"/>
1395  <x:anchor-alias value="OWS"/>
1396  <x:anchor-alias value="HTTP-date"/>
1397  <x:anchor-alias value="entity-tag"/>
1399  The following core rules are included by
[1806]1400  reference, as defined in <xref target="RFC5234" x:fmt="of" x:sec="B.1"/>:
[1805]1401  ALPHA (letters), CR (carriage return), CRLF (CR LF), CTL (controls),
1402  DIGIT (decimal 0-9), DQUOTE (double quote),
1403  HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed),
1404  OCTET (any 8-bit sequence of data), SP (space), and
1405  VCHAR (any visible US-ASCII character).
1408  Note that all rules derived from <x:ref>token</x:ref> are to
1409  be compared case-insensitively, like <x:ref>range-unit</x:ref> and
1410  <x:ref>acceptable-ranges</x:ref>.
1413  The rules below are defined in <xref target="Part1"/>:
1415<figure><artwork type="abnf2616">
1416  <x:ref>OWS</x:ref>        = &lt;OWS, defined in &whitespace;&gt;
1417  <x:ref>token</x:ref>      = &lt;token, defined in &field-components;&gt;
1420  The rules below are defined in other parts:
1422<figure><artwork type="abnf2616">
1423  <x:ref>HTTP-date</x:ref>  = &lt;HTTP-date, defined in &http-date;&gt;
1424  <x:ref>entity-tag</x:ref> = &lt;entity-tag, defined in &entity-tags;&gt;
[680]1428<?BEGININC p5-range.abnf-appendix ?>
[427]1429<section xmlns:x="" title="Collected ABNF" anchor="collected.abnf">
1431  In the collected ABNF below, list rules are expanded as per <xref target="Part1" x:rel="#notation"/>.
[427]1433<artwork type="abnf" name="p5-range.parsed-abnf">
[1232]1434<x:ref>Accept-Ranges</x:ref> = acceptable-ranges
[2135]1436<x:ref>Content-Range</x:ref> = byte-content-range / other-content-range
[2052]1438<x:ref>HTTP-date</x:ref> = &lt;HTTP-date, defined in [Part2], Section;
[1232]1440<x:ref>If-Range</x:ref> = entity-tag / HTTP-date
[2045]1442<x:ref>OWS</x:ref> = &lt;OWS, defined in [Part1], Section 3.2.3&gt;
[1232]1444<x:ref>Range</x:ref> = byte-ranges-specifier / other-ranges-specifier
1446<x:ref>acceptable-ranges</x:ref> = ( *( "," OWS ) range-unit *( OWS "," [ OWS
[425]1447 range-unit ] ) ) / "none"
[2138]1449<x:ref>byte-content-range</x:ref> = bytes-unit SP ( byte-range-resp /
[2135]1450 unsatisfied-range )
1451<x:ref>byte-range</x:ref> = first-byte-pos "-" last-byte-pos
1452<x:ref>byte-range-resp</x:ref> = byte-range "/" ( complete-length / "*" )
[1663]1453<x:ref>byte-range-set</x:ref> = *( "," OWS ) ( byte-range-spec /
1454 suffix-byte-range-spec ) *( OWS "," [ OWS ( byte-range-spec /
1455 suffix-byte-range-spec ) ] )
[427]1456<x:ref>byte-range-spec</x:ref> = first-byte-pos "-" [ last-byte-pos ]
1457<x:ref>byte-ranges-specifier</x:ref> = bytes-unit "=" byte-range-set
1458<x:ref>bytes-unit</x:ref> = "bytes"
[2135]1460<x:ref>complete-length</x:ref> = 1*DIGIT
[1383]1462<x:ref>entity-tag</x:ref> = &lt;entity-tag, defined in [Part4], Section 2.3&gt;
1464<x:ref>first-byte-pos</x:ref> = 1*DIGIT
1466<x:ref>last-byte-pos</x:ref> = 1*DIGIT
[2135]1468<x:ref>other-content-range</x:ref> = other-range-unit SP other-range-resp
1469<x:ref>other-range-resp</x:ref> = *CHAR
[638]1470<x:ref>other-range-set</x:ref> = 1*CHAR
[427]1471<x:ref>other-range-unit</x:ref> = token
[638]1472<x:ref>other-ranges-specifier</x:ref> = other-range-unit "=" other-range-set
1474<x:ref>range-unit</x:ref> = bytes-unit / other-range-unit
1476<x:ref>suffix-byte-range-spec</x:ref> = "-" suffix-length
1477<x:ref>suffix-length</x:ref> = 1*DIGIT
[2045]1479<x:ref>token</x:ref> = &lt;token, defined in [Part1], Section 3.2.6&gt;
1481<x:ref>unsatisfied-range</x:ref> = "*/" complete-length
[680]1485<?ENDINC p5-range.abnf-appendix ?>
[252]1488<section title="Change Log (to be removed by RFC Editor before publication)" anchor="change.log">
[1804]1490  Changes up to the first Working Group Last Call draft are summarized
1491  in <eref target=""/>.
[1592]1494<section title="Since draft-ietf-httpbis-p5-range-19" anchor="changes.since.19">
[1663]1496  Closed issues:
1497  <list style="symbols"> 
1498    <t>
1499      <eref target=""/>:
1500      "ABNF list expansion code problem"
1501    </t>
[1682]1502    <t>
1503      <eref target=""/>:
1504      "ABNF requirements for recipients"
1505    </t>
[1748]1506    <t>
1507      <eref target=""/>:
1508      "reserve 'none' as byte range unit"
1509    </t>
[1760]1510    <t>
1511      <eref target=""/>:
1512      "note introduction of new IANA registries as normative changes"
1513    </t>
[1767]1514    <t>
1515      <eref target=""/>:
1516      "range units vs leading zeroes vs size"
1517    </t>
[1663]1518  </list>
[1807]1522<section title="Since draft-ietf-httpbis-p5-range-20" anchor="changes.since.20">
[1889]1524  <list style="symbols">
1525    <t>
1526      Conformance criteria and considerations regarding error handling are
1527      now defined in Part 1.
1528    </t>
1529  </list>
[1929]1533<section title="Since draft-ietf-httpbis-p5-range-21" anchor="changes.since.21">
[2159]1535  Closed issues:
1536  <list style="symbols"> 
1537    <t>
1538      <eref target=""/>:
1539      "Security consideration: range flooding"
1540    </t>
1541    <t>
[2168]1542      <eref target=""/>:
1543      "Allowing heuristic caching for new status codes"
1544    </t>
1545    <t>
[2159]1546      <eref target=""/>:
1547      "Add limitations to Range to reduce its use as a denial-of-service tool"
1548    </t>
[2200]1549    <t>
1550      <eref target=""/>:
1551      "416 and multipart/byteranges"
1552    </t>
[2159]1553  </list>
[2190]1557<section title="Since draft-ietf-httpbis-p5-range-22" anchor="changes.since.22">
[2206]1559  Closed issues:
1560  <list style="symbols">
1561    <t>
1562      <eref target=""/>:
1563      "explain list expansion in ABNF appendices"
1564    </t>
[2207]1565    <t>
1566      <eref target=""/>:
1567      "incorrect example dates"
1568    </t>
[2208]1569    <t>
1570      <eref target=""/>:
1571      "media type registration template issues"
1572    </t>
[2290]1573    <t>
[2296]1574      <eref target=""/>:
1575      "Editorial suggestions"
1576    </t>
1577    <t>
[2290]1578      <eref target=""/>:
1579      "MUSTs and other feedback"
1580    </t>
[2206]1581  </list>
1585<section title="Since draft-ietf-httpbis-p5-range-23" anchor="changes.since.23">
1587  None yet.
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