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4Network Working Group                                   R. Fielding, Ed.
5Internet-Draft                                              Day Software
6Obsoletes: 2068, 2616                                          J. Gettys
7(if approved)                                       One Laptop per Child
8Intended status: Standards Track                                J. Mogul
9Expires: June 22, 2008                                                HP
10                                                              H. Frystyk
11                                                               Microsoft
12                                                             L. Masinter
13                                                           Adobe Systems
14                                                                P. Leach
15                                                               Microsoft
16                                                          T. Berners-Lee
17                                                                 W3C/MIT
18                                                       December 20, 2007
19
20
21         HTTP/1.1, part 5: Range Requests and Partial Responses
22                     draft-ietf-httpbis-p5-range-00
23
24Status of this Memo
25
26   By submitting this Internet-Draft, each author represents that any
27   applicable patent or other IPR claims of which he or she is aware
28   have been or will be disclosed, and any of which he or she becomes
29   aware will be disclosed, in accordance with Section 6 of BCP 79.
30
31   Internet-Drafts are working documents of the Internet Engineering
32   Task Force (IETF), its areas, and its working groups.  Note that
33   other groups may also distribute working documents as Internet-
34   Drafts.
35
36   Internet-Drafts are draft documents valid for a maximum of six months
37   and may be updated, replaced, or obsoleted by other documents at any
38   time.  It is inappropriate to use Internet-Drafts as reference
39   material or to cite them other than as "work in progress."
40
41   The list of current Internet-Drafts can be accessed at
42   http://www.ietf.org/ietf/1id-abstracts.txt.
43
44   The list of Internet-Draft Shadow Directories can be accessed at
45   http://www.ietf.org/shadow.html.
46
47   This Internet-Draft will expire on June 22, 2008.
48
49Copyright Notice
50
51   Copyright (C) The IETF Trust (2007).
52
53
54
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57Internet-Draft                  HTTP/1.1                   December 2007
58
59
60Abstract
61
62   The Hypertext Transfer Protocol (HTTP) is an application-level
63   protocol for distributed, collaborative, hypermedia information
64   systems.  HTTP has been in use by the World Wide Web global
65   information initiative since 1990.  This document is Part 5 of the
66   seven-part specification that defines the protocol referred to as
67   "HTTP/1.1" and, taken together, obsoletes RFC 2616.  Part 5 defines
68   range-specific requests and the rules for constructing and combining
69   responses to those requests.
70
71Editorial Note (To be removed by RFC Editor)
72
73   This version of the HTTP specification contains only minimal
74   editorial changes from [RFC2616] (abstract, introductory paragraph,
75   and authors' addresses).  All other changes are due to partitioning
76   the original into seven mostly independent parts.  The intent is for
77   readers of future drafts to able to use draft 00 as the basis for
78   comparison when the WG makes later changes to the specification text.
79   This draft will shortly be followed by draft 01 (containing the first
80   round of changes that have already been agreed to on the mailing
81   list).  There is no point in reviewing this draft other than to
82   verify that the partitioning has been done correctly.  Roy T.
83   Fielding, Yves Lafon, and Julian Reschke will be the editors after
84   draft 00 is submitted.
85
86   Discussion of this draft should take place on the HTTPBIS working
87   group mailing list (ietf-http-wg@w3.org).  The current issues list is
88   at <http://www3.tools.ietf.org/wg/httpbis/trac/report/11> and related
89   documents (including fancy diffs) can be found at
90   <http://www3.tools.ietf.org/wg/httpbis/>.
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113Internet-Draft                  HTTP/1.1                   December 2007
114
115
116Table of Contents
117
118   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
119   2.  Range Units  . . . . . . . . . . . . . . . . . . . . . . . . .  4
120   3.  Status Code Definitions  . . . . . . . . . . . . . . . . . . .  4
121     3.1.  206 Partial Content  . . . . . . . . . . . . . . . . . . .  4
122     3.2.  416 Requested Range Not Satisfiable  . . . . . . . . . . .  5
123   4.  Combining Byte Ranges  . . . . . . . . . . . . . . . . . . . .  5
124   5.  Header Field Definitions . . . . . . . . . . . . . . . . . . .  6
125     5.1.  Accept-Ranges  . . . . . . . . . . . . . . . . . . . . . .  6
126     5.2.  Content-Range  . . . . . . . . . . . . . . . . . . . . . .  7
127     5.3.  If-Range . . . . . . . . . . . . . . . . . . . . . . . . .  9
128     5.4.  Range  . . . . . . . . . . . . . . . . . . . . . . . . . .  9
129       5.4.1.  Byte Ranges  . . . . . . . . . . . . . . . . . . . . .  9
130       5.4.2.  Range Retrieval Requests . . . . . . . . . . . . . . . 11
131   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 12
132   7.  Security Considerations  . . . . . . . . . . . . . . . . . . . 12
133   8.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 12
134   9.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
135   Appendix A.  Internet Media Type multipart/byteranges  . . . . . . 13
136   Appendix B.  Changes from RFC 2068 . . . . . . . . . . . . . . . . 14
137   Index  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
138   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
139   Intellectual Property and Copyright Statements . . . . . . . . . . 18
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171
1721.  Introduction
173
174   This document will define aspects of HTTP related to range requests,
175   partial responses, and the multipart/byteranges media type.  Right
176   now it only includes the extracted relevant sections of RFC 2616
177   [RFC2616] without edit.
178
179
1802.  Range Units
181
182   HTTP/1.1 allows a client to request that only part (a range of) the
183   response entity be included within the response.  HTTP/1.1 uses range
184   units in the Range (Section 5.4) and Content-Range (Section 5.2)
185   header fields.  An entity can be broken down into subranges according
186   to various structural units.
187
188      range-unit       = bytes-unit | other-range-unit
189      bytes-unit       = "bytes"
190      other-range-unit = token
191
192   The only range unit defined by HTTP/1.1 is "bytes".  HTTP/1.1
193   implementations MAY ignore ranges specified using other units.
194
195   HTTP/1.1 has been designed to allow implementations of applications
196   that do not depend on knowledge of ranges.
197
198
1993.  Status Code Definitions
200
2013.1.  206 Partial Content
202
203   The server has fulfilled the partial GET request for the resource.
204   The request MUST have included a Range header field (Section 5.4)
205   indicating the desired range, and MAY have included an If-Range
206   header field (Section 5.3) to make the request conditional.
207
208   The response MUST include the following header fields:
209
210   o  Either a Content-Range header field (Section 5.2) indicating the
211      range included with this response, or a multipart/byteranges
212      Content-Type including Content-Range fields for each part.  If a
213      Content-Length header field is present in the response, its value
214      MUST match the actual number of OCTETs transmitted in the message-
215      body.
216
217   o  Date
218
219
220
221
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227
228   o  ETag and/or Content-Location, if the header would have been sent
229      in a 200 response to the same request
230
231   o  Expires, Cache-Control, and/or Vary, if the field-value might
232      differ from that sent in any previous response for the same
233      variant
234
235   If the 206 response is the result of an If-Range request that used a
236   strong cache validator (see Section 4 of [Part4]), the response
237   SHOULD NOT include other entity-headers.  If the response is the
238   result of an If-Range request that used a weak validator, the
239   response MUST NOT include other entity-headers; this prevents
240   inconsistencies between cached entity-bodies and updated headers.
241   Otherwise, the response MUST include all of the entity-headers that
242   would have been returned with a 200 (OK) response to the same
243   request.
244
245   A cache MUST NOT combine a 206 response with other previously cached
246   content if the ETag or Last-Modified headers do not match exactly,
247   see 4.
248
249   A cache that does not support the Range and Content-Range headers
250   MUST NOT cache 206 (Partial) responses.
251
2523.2.  416 Requested Range Not Satisfiable
253
254   A server SHOULD return a response with this status code if a request
255   included a Range request-header field (Section 5.4), and none of the
256   range-specifier values in this field overlap the current extent of
257   the selected resource, and the request did not include an If-Range
258   request-header field.  (For byte-ranges, this means that the first-
259   byte-pos of all of the byte-range-spec values were greater than the
260   current length of the selected resource.)
261
262   When this status code is returned for a byte-range request, the
263   response SHOULD include a Content-Range entity-header field
264   specifying the current length of the selected resource (see
265   Section 5.2).  This response MUST NOT use the multipart/byteranges
266   content-type.
267
268
2694.  Combining Byte Ranges
270
271   A response might transfer only a subrange of the bytes of an entity-
272   body, either because the request included one or more Range
273   specifications, or because a connection was broken prematurely.
274   After several such transfers, a cache might have received several
275   ranges of the same entity-body.
276
277
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283
284   If a cache has a stored non-empty set of subranges for an entity, and
285   an incoming response transfers another subrange, the cache MAY
286   combine the new subrange with the existing set if both the following
287   conditions are met:
288
289   o  Both the incoming response and the cache entry have a cache
290      validator.
291
292   o  The two cache validators match using the strong comparison
293      function (see Section 4 of [Part4]).
294
295   If either requirement is not met, the cache MUST use only the most
296   recent partial response (based on the Date values transmitted with
297   every response, and using the incoming response if these values are
298   equal or missing), and MUST discard the other partial information.
299
300
3015.  Header Field Definitions
302
303   This section defines the syntax and semantics of all standard
304   HTTP/1.1 header fields.  For entity-header fields, both sender and
305   recipient refer to either the client or the server, depending on who
306   sends and who receives the entity.
307
3085.1.  Accept-Ranges
309
310   The Accept-Ranges response-header field allows the server to indicate
311   its acceptance of range requests for a resource:
312
313          Accept-Ranges     = "Accept-Ranges" ":" acceptable-ranges
314          acceptable-ranges = 1#range-unit | "none"
315
316   Origin servers that accept byte-range requests MAY send
317
318          Accept-Ranges: bytes
319
320   but are not required to do so.  Clients MAY generate byte-range
321   requests without having received this header for the resource
322   involved.  Range units are defined in Section 2.
323
324   Servers that do not accept any kind of range request for a resource
325   MAY send
326
327          Accept-Ranges: none
328
329   to advise the client not to attempt a range request.
330
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3405.2.  Content-Range
341
342   The Content-Range entity-header is sent with a partial entity-body to
343   specify where in the full entity-body the partial body should be
344   applied.  Range units are defined in Section 2.
345
346       Content-Range = "Content-Range" ":" content-range-spec
347
348       content-range-spec      = byte-content-range-spec
349       byte-content-range-spec = bytes-unit SP
350                                 byte-range-resp-spec "/"
351                                 ( instance-length | "*" )
352
353       byte-range-resp-spec = (first-byte-pos "-" last-byte-pos)
354                                      | "*"
355       instance-length           = 1*DIGIT
356
357   The header SHOULD indicate the total length of the full entity-body,
358   unless this length is unknown or difficult to determine.  The
359   asterisk "*" character means that the instance-length is unknown at
360   the time when the response was generated.
361
362   Unlike byte-ranges-specifier values (see Section 5.4.1), a byte-
363   range-resp-spec MUST only specify one range, and MUST contain
364   absolute byte positions for both the first and last byte of the
365   range.
366
367   A byte-content-range-spec with a byte-range-resp-spec whose last-
368   byte-pos value is less than its first-byte-pos value, or whose
369   instance-length value is less than or equal to its last-byte-pos
370   value, is invalid.  The recipient of an invalid byte-content-range-
371   spec MUST ignore it and any content transferred along with it.
372
373   A server sending a response with status code 416 (Requested range not
374   satisfiable) SHOULD include a Content-Range field with a byte-range-
375   resp-spec of "*".  The instance-length specifies the current length
376   of the selected resource.  A response with status code 206 (Partial
377   Content) MUST NOT include a Content-Range field with a byte-range-
378   resp-spec of "*".
379
380   Examples of byte-content-range-spec values, assuming that the entity
381   contains a total of 1234 bytes:
382
383   o  The first 500 bytes:
384
385      bytes 0-499/1234
386
387
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389
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395
396   o  The second 500 bytes:
397
398      bytes 500-999/1234
399
400   o  All except for the first 500 bytes:
401
402      bytes 500-1233/1234
403
404   o  The last 500 bytes:
405
406      bytes 734-1233/1234
407
408   When an HTTP message includes the content of a single range (for
409   example, a response to a request for a single range, or to a request
410   for a set of ranges that overlap without any holes), this content is
411   transmitted with a Content-Range header, and a Content-Length header
412   showing the number of bytes actually transferred.  For example,
413
414       HTTP/1.1 206 Partial content
415       Date: Wed, 15 Nov 1995 06:25:24 GMT
416       Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
417       Content-Range: bytes 21010-47021/47022
418       Content-Length: 26012
419       Content-Type: image/gif
420
421   When an HTTP message includes the content of multiple ranges (for
422   example, a response to a request for multiple non-overlapping
423   ranges), these are transmitted as a multipart message.  The multipart
424   media type used for this purpose is "multipart/byteranges" as defined
425   in Appendix A.  See Appendix B for a compatibility issue.
426
427   A response to a request for a single range MUST NOT be sent using the
428   multipart/byteranges media type.  A response to a request for
429   multiple ranges, whose result is a single range, MAY be sent as a
430   multipart/byteranges media type with one part.  A client that cannot
431   decode a multipart/byteranges message MUST NOT ask for multiple byte-
432   ranges in a single request.
433
434   When a client requests multiple byte-ranges in one request, the
435   server SHOULD return them in the order that they appeared in the
436   request.
437
438   If the server ignores a byte-range-spec because it is syntactically
439   invalid, the server SHOULD treat the request as if the invalid Range
440   header field did not exist.  (Normally, this means return a 200
441   response containing the full entity).
442
443   If the server receives a request (other than one including an If-
444
445
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451
452   Range request-header field) with an unsatisfiable Range request-
453   header field (that is, all of whose byte-range-spec values have a
454   first-byte-pos value greater than the current length of the selected
455   resource), it SHOULD return a response code of 416 (Requested range
456   not satisfiable) (Section 3.2).
457
458      Note: clients cannot depend on servers to send a 416 (Requested
459      range not satisfiable) response instead of a 200 (OK) response for
460      an unsatisfiable Range request-header, since not all servers
461      implement this request-header.
462
4635.3.  If-Range
464
465   If a client has a partial copy of an entity in its cache, and wishes
466   to have an up-to-date copy of the entire entity in its cache, it
467   could use the Range request-header with a conditional GET (using
468   either or both of If-Unmodified-Since and If-Match.)  However, if the
469   condition fails because the entity has been modified, the client
470   would then have to make a second request to obtain the entire current
471   entity-body.
472
473   The If-Range header allows a client to "short-circuit" the second
474   request.  Informally, its meaning is `if the entity is unchanged,
475   send me the part(s) that I am missing; otherwise, send me the entire
476   new entity'.
477
478        If-Range = "If-Range" ":" ( entity-tag | HTTP-date )
479
480   If the client has no entity tag for an entity, but does have a Last-
481   Modified date, it MAY use that date in an If-Range header.  (The
482   server can distinguish between a valid HTTP-date and any form of
483   entity-tag by examining no more than two characters.)  The If-Range
484   header SHOULD only be used together with a Range header, and MUST be
485   ignored if the request does not include a Range header, or if the
486   server does not support the sub-range operation.
487
488   If the entity tag given in the If-Range header matches the current
489   entity tag for the entity, then the server SHOULD provide the
490   specified sub-range of the entity using a 206 (Partial content)
491   response.  If the entity tag does not match, then the server SHOULD
492   return the entire entity using a 200 (OK) response.
493
4945.4.  Range
495
4965.4.1.  Byte Ranges
497
498   Since all HTTP entities are represented in HTTP messages as sequences
499   of bytes, the concept of a byte range is meaningful for any HTTP
500
501
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507
508   entity.  (However, not all clients and servers need to support byte-
509   range operations.)
510
511   Byte range specifications in HTTP apply to the sequence of bytes in
512   the entity-body (not necessarily the same as the message-body).
513
514   A byte range operation MAY specify a single range of bytes, or a set
515   of ranges within a single entity.
516
517       ranges-specifier = byte-ranges-specifier
518       byte-ranges-specifier = bytes-unit "=" byte-range-set
519       byte-range-set  = 1#( byte-range-spec | suffix-byte-range-spec )
520       byte-range-spec = first-byte-pos "-" [last-byte-pos]
521       first-byte-pos  = 1*DIGIT
522       last-byte-pos   = 1*DIGIT
523
524   The first-byte-pos value in a byte-range-spec gives the byte-offset
525   of the first byte in a range.  The last-byte-pos value gives the
526   byte-offset of the last byte in the range; that is, the byte
527   positions specified are inclusive.  Byte offsets start at zero.
528
529   If the last-byte-pos value is present, it MUST be greater than or
530   equal to the first-byte-pos in that byte-range-spec, or the byte-
531   range-spec is syntactically invalid.  The recipient of a byte-range-
532   set that includes one or more syntactically invalid byte-range-spec
533   values MUST ignore the header field that includes that byte-range-
534   set.
535
536   If the last-byte-pos value is absent, or if the value is greater than
537   or equal to the current length of the entity-body, last-byte-pos is
538   taken to be equal to one less than the current length of the entity-
539   body in bytes.
540
541   By its choice of last-byte-pos, a client can limit the number of
542   bytes retrieved without knowing the size of the entity.
543
544       suffix-byte-range-spec = "-" suffix-length
545       suffix-length = 1*DIGIT
546
547   A suffix-byte-range-spec is used to specify the suffix of the entity-
548   body, of a length given by the suffix-length value.  (That is, this
549   form specifies the last N bytes of an entity-body.)  If the entity is
550   shorter than the specified suffix-length, the entire entity-body is
551   used.
552
553   If a syntactically valid byte-range-set includes at least one byte-
554   range-spec whose first-byte-pos is less than the current length of
555   the entity-body, or at least one suffix-byte-range-spec with a non-
556
557
558
559Fielding, et al.          Expires June 22, 2008                [Page 10]
560
561Internet-Draft                  HTTP/1.1                   December 2007
562
563
564   zero suffix-length, then the byte-range-set is satisfiable.
565   Otherwise, the byte-range-set is unsatisfiable.  If the byte-range-
566   set is unsatisfiable, the server SHOULD return a response with a
567   status of 416 (Requested range not satisfiable).  Otherwise, the
568   server SHOULD return a response with a status of 206 (Partial
569   Content) containing the satisfiable ranges of the entity-body.
570
571   Examples of byte-ranges-specifier values (assuming an entity-body of
572   length 10000):
573
574   o  The first 500 bytes (byte offsets 0-499, inclusive): bytes=0-499
575
576   o  The second 500 bytes (byte offsets 500-999, inclusive): bytes=500-
577      999
578
579   o  The final 500 bytes (byte offsets 9500-9999, inclusive): bytes=-
580      500
581
582   o  Or bytes=9500-
583
584   o  The first and last bytes only (bytes 0 and 9999): bytes=0-0,-1
585
586   o  Several legal but not canonical specifications of the second 500
587      bytes (byte offsets 500-999, inclusive):
588      bytes=500-600,601-999
589      bytes=500-700,601-999
590
5915.4.2.  Range Retrieval Requests
592
593   HTTP retrieval requests using conditional or unconditional GET
594   methods MAY request one or more sub-ranges of the entity, instead of
595   the entire entity, using the Range request header, which applies to
596   the entity returned as the result of the request:
597
598      Range = "Range" ":" ranges-specifier
599
600   A server MAY ignore the Range header.  However, HTTP/1.1 origin
601   servers and intermediate caches ought to support byte ranges when
602   possible, since Range supports efficient recovery from partially
603   failed transfers, and supports efficient partial retrieval of large
604   entities.
605
606   If the server supports the Range header and the specified range or
607   ranges are appropriate for the entity:
608
609   o  The presence of a Range header in an unconditional GET modifies
610      what is returned if the GET is otherwise successful.  In other
611      words, the response carries a status code of 206 (Partial Content)
612
613
614
615Fielding, et al.          Expires June 22, 2008                [Page 11]
616
617Internet-Draft                  HTTP/1.1                   December 2007
618
619
620      instead of 200 (OK).
621
622   o  The presence of a Range header in a conditional GET (a request
623      using one or both of If-Modified-Since and If-None-Match, or one
624      or both of If-Unmodified-Since and If-Match) modifies what is
625      returned if the GET is otherwise successful and the condition is
626      true.  It does not affect the 304 (Not Modified) response returned
627      if the conditional is false.
628
629   In some cases, it might be more appropriate to use the If-Range
630   header (see Section 5.3) in addition to the Range header.
631
632   If a proxy that supports ranges receives a Range request, forwards
633   the request to an inbound server, and receives an entire entity in
634   reply, it SHOULD only return the requested range to its client.  It
635   SHOULD store the entire received response in its cache if that is
636   consistent with its cache allocation policies.
637
638
6396.  IANA Considerations
640
641   TBD.
642
643
6447.  Security Considerations
645
646   No additional security considerations have been identified beyond
647   those applicable to HTTP in general [Part1].
648
649
6508.  Acknowledgments
651
652   Most of the specification of ranges is based on work originally done
653   by Ari Luotonen and John Franks, with additional input from Steve
654   Zilles.
655
656   Based on an XML translation of RFC 2616 by Julian Reschke.
657
658
6599.  References
660
661   [Part1]    Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
662              Masinter, L., Leach, P., and T. Berners-Lee, "HTTP/1.1,
663              part 1: URIs, Connections, and Message Parsing",
664              draft-ietf-httpbis-p1-messaging-00 (work in progress),
665              December 2007.
666
667   [Part4]    Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
668
669
670
671Fielding, et al.          Expires June 22, 2008                [Page 12]
672
673Internet-Draft                  HTTP/1.1                   December 2007
674
675
676              Masinter, L., Leach, P., and T. Berners-Lee, "HTTP/1.1,
677              part 4: Conditional Requests",
678              draft-ietf-httpbis-p4-conditional-00 (work in progress),
679              December 2007.
680
681   [RFC2046]  Freed, N. and N. Borenstein, "Multipurpose Internet Mail
682              Extensions (MIME) Part Two: Media Types", RFC 2046,
683              November 1996.
684
685   [RFC2616]  Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
686              Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
687              Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
688
689
690Appendix A.  Internet Media Type multipart/byteranges
691
692   When an HTTP 206 (Partial Content) response message includes the
693   content of multiple ranges (a response to a request for multiple non-
694   overlapping ranges), these are transmitted as a multipart message-
695   body.  The media type for this purpose is called "multipart/
696   byteranges".
697
698   The multipart/byteranges media type includes two or more parts, each
699   with its own Content-Type and Content-Range fields.  The required
700   boundary parameter specifies the boundary string used to separate
701   each body-part.
702
703   Media Type name:  multipart
704
705   Media subtype name:  byteranges
706
707   Required parameters:  boundary
708
709   Optional parameters:  none
710
711   Encoding considerations:  only "7bit", "8bit", or "binary" are
712      permitted
713
714   Security considerations:  none
715
716
717
718
719
720
721
722
723
724
725
726
727Fielding, et al.          Expires June 22, 2008                [Page 13]
728
729Internet-Draft                  HTTP/1.1                   December 2007
730
731
732   For example:
733
734      HTTP/1.1 206 Partial Content
735      Date: Wed, 15 Nov 1995 06:25:24 GMT
736      Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
737      Content-type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
738
739      --THIS_STRING_SEPARATES
740      Content-type: application/pdf
741      Content-range: bytes 500-999/8000
742
743      ...the first range...
744      --THIS_STRING_SEPARATES
745      Content-type: application/pdf
746      Content-range: bytes 7000-7999/8000
747
748      ...the second range
749      --THIS_STRING_SEPARATES--
750
751   Notes:
752
753   1.  Additional CRLFs may precede the first boundary string in the
754       entity.
755
756   2.  Although RFC 2046 [RFC2046] permits the boundary string to be
757       quoted, some existing implementations handle a quoted boundary
758       string incorrectly.
759
760   3.  A number of browsers and servers were coded to an early draft of
761       the byteranges specification to use a media type of multipart/
762       x-byteranges, which is almost, but not quite compatible with the
763       version documented in HTTP/1.1.
764
765
766Appendix B.  Changes from RFC 2068
767
768   There are situations where a server (especially a proxy) does not
769   know the full length of a response but is capable of serving a
770   byterange request.  We therefore need a mechanism to allow byteranges
771   with a content-range not indicating the full length of the message.
772   (Section 5.2)
773
774   Range request responses would become very verbose if all meta-data
775   were always returned; by allowing the server to only send needed
776   headers in a 206 response, this problem can be avoided.
777
778   Fix problem with unsatisfiable range requests; there are two cases:
779   syntactic problems, and range doesn't exist in the document.  The 416
780
781
782
783Fielding, et al.          Expires June 22, 2008                [Page 14]
784
785Internet-Draft                  HTTP/1.1                   December 2007
786
787
788   status code was needed to resolve this ambiguity needed to indicate
789   an error for a byte range request that falls outside of the actual
790   contents of a document.  (Section 3.2, 5.2)
791
792
793Index
794
795   2
796      206 Partial Content (status code)  4
797
798   4
799      416 Requested Range Not Satisfiable (status code)  5
800
801   A
802      Accept-Ranges header  6
803
804   C
805      Content-Range header  7
806
807   G
808      Grammar
809         Accept-Ranges  6
810         acceptable-ranges  6
811         byte-content-range-spec  7
812         byte-range-resp-spec  7
813         byte-range-set  10
814         byte-range-spec  10
815         byte-ranges-specifier  10
816         bytes-unit  4
817         Content-Range  7
818         content-range-spec  7
819         first-byte-pos  10
820         If-Range  9
821         instance-length  7
822         last-byte-pos  10
823         other-range-unit  4
824         Range  11
825         range-unit  4
826         ranges-specifier  10
827         suffix-byte-range-spec  10
828         suffix-length  10
829
830   H
831      Headers
832         Accept-Ranges  6
833         Content-Range  7
834         If-Range  9
835         Range  9
836
837
838
839Fielding, et al.          Expires June 22, 2008                [Page 15]
840
841Internet-Draft                  HTTP/1.1                   December 2007
842
843
844   I
845      If-Range header  9
846
847   M
848      Media Type
849         multipart/byteranges  13
850         multipart/x-byteranges  14
851      multipart/byteranges Media Type  13
852      multipart/x-byteranges Media Type  14
853
854   R
855      Range header  9
856
857   S
858      Status Codes
859         206 Partial Content  4
860         416 Requested Range Not Satisfiable  5
861
862
863Authors' Addresses
864
865   Roy T. Fielding (editor)
866   Day Software
867   23 Corporate Plaza DR, Suite 280
868   Newport Beach, CA  92660
869   USA
870
871   Phone: +1-949-706-5300
872   Fax:   +1-949-706-5305
873   Email: fielding@gbiv.com
874   URI:   http://roy.gbiv.com/
875
876
877   Jim Gettys
878   One Laptop per Child
879   21 Oak Knoll Road
880   Carlisle, MA  01741
881   USA
882
883   Email: jg@laptop.org
884   URI:   http://www.laptop.org/
885
886
887
888
889
890
891
892
893
894
895Fielding, et al.          Expires June 22, 2008                [Page 16]
896
897Internet-Draft                  HTTP/1.1                   December 2007
898
899
900   Jeffrey C. Mogul
901   Hewlett-Packard Company
902   HP Labs, Large Scale Systems Group
903   1501 Page Mill Road, MS 1177
904   Palo Alto, CA  94304
905   USA
906
907   Email: JeffMogul@acm.org
908
909
910   Henrik Frystyk Nielsen
911   Microsoft Corporation
912   1 Microsoft Way
913   Redmond, WA  98052
914   USA
915
916   Email: henrikn@microsoft.com
917
918
919   Larry Masinter
920   Adobe Systems, Incorporated
921   345 Park Ave
922   San Jose, CA  95110
923   USA
924
925   Email: LMM@acm.org
926   URI:   http://larry.masinter.net/
927
928
929   Paul J. Leach
930   Microsoft Corporation
931   1 Microsoft Way
932   Redmond, WA  98052
933
934   Email: paulle@microsoft.com
935
936
937   Tim Berners-Lee
938   World Wide Web Consortium
939   MIT Computer Science and Artificial Intelligence Laboratory
940   The Stata Center, Building 32
941   32 Vassar Street
942   Cambridge, MA  02139
943   USA
944
945   Email: timbl@w3.org
946   URI:   http://www.w3.org/People/Berners-Lee/
947
948
949
950
951Fielding, et al.          Expires June 22, 2008                [Page 17]
952
953Internet-Draft                  HTTP/1.1                   December 2007
954
955
956Full Copyright Statement
957
958   Copyright (C) The IETF Trust (2007).
959
960   This document is subject to the rights, licenses and restrictions
961   contained in BCP 78, and except as set forth therein, the authors
962   retain all their rights.
963
964   This document and the information contained herein are provided on an
965   "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
966   OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
967   THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
968   OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
969   THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
970   WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
971
972
973Intellectual Property
974
975   The IETF takes no position regarding the validity or scope of any
976   Intellectual Property Rights or other rights that might be claimed to
977   pertain to the implementation or use of the technology described in
978   this document or the extent to which any license under such rights
979   might or might not be available; nor does it represent that it has
980   made any independent effort to identify any such rights.  Information
981   on the procedures with respect to rights in RFC documents can be
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983
984   Copies of IPR disclosures made to the IETF Secretariat and any
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986   attempt made to obtain a general license or permission for the use of
987   such proprietary rights by implementers or users of this
988   specification can be obtained from the IETF on-line IPR repository at
989   http://www.ietf.org/ipr.
990
991   The IETF invites any interested party to bring to its attention any
992   copyrights, patents or patent applications, or other proprietary
993   rights that may cover technology that may be required to implement
994   this standard.  Please address the information to the IETF at
995   ietf-ipr@ietf.org.
996
997
998Acknowledgment
999
1000   Funding for the RFC Editor function is provided by the IETF
1001   Administrative Support Activity (IASA).
1002
1003
1004
1005
1006
1007Fielding, et al.          Expires June 22, 2008                [Page 18]
1008
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