HTTPbis Working Group R. Fielding, Ed.
Internet-Draft Day Software
Obsoletes: 2616 (if approved) J. Gettys
Intended status: Standards Track Alcatel-Lucent
Expires: February 5, 2011 J. Mogul
HP
H. Frystyk
Microsoft
L. Masinter
Adobe Systems
P. Leach
Microsoft
T. Berners-Lee
W3C/MIT
Y. Lafon, Ed.
W3C
J. Reschke, Ed.
greenbytes
August 4, 2010
HTTP/1.1, part 5: Range Requests and Partial Responses
draft-ietf-httpbis-p5-range-11
Abstract
The Hypertext Transfer Protocol (HTTP) is an application-level
protocol for distributed, collaborative, hypermedia information
systems. HTTP has been in use by the World Wide Web global
information initiative since 1990. This document is Part 5 of the
seven-part specification that defines the protocol referred to as
"HTTP/1.1" and, taken together, obsoletes RFC 2616. Part 5 defines
range-specific requests and the rules for constructing and combining
responses to those requests.
Editorial Note (To be removed by RFC Editor)
Discussion of this draft should take place on the HTTPBIS working
group mailing list (ietf-http-wg@w3.org). The current issues list is
at <http://tools.ietf.org/wg/httpbis/trac/report/3> and related
documents (including fancy diffs) can be found at
<http://tools.ietf.org/wg/httpbis/>.
The changes in this draft are summarized in Appendix D.12.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
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provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on February 5, 2011.
Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
This document may contain material from IETF Documents or IETF
Contributions published or made publicly available before November
10, 2008. The person(s) controlling the copyright in some of this
material may not have granted the IETF Trust the right to allow
modifications of such material outside the IETF Standards Process.
Without obtaining an adequate license from the person(s) controlling
the copyright in such materials, this document may not be modified
outside the IETF Standards Process, and derivative works of it may
not be created outside the IETF Standards Process, except to format
it for publication as an RFC or to translate it into languages other
than English.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5
1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . . 5
1.2. Syntax Notation . . . . . . . . . . . . . . . . . . . . . 5
1.2.1. Core Rules . . . . . . . . . . . . . . . . . . . . . . 6
1.2.2. ABNF Rules defined in other Parts of the
Specification . . . . . . . . . . . . . . . . . . . . 6
2. Range Units . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.1. Range Specifier Registry . . . . . . . . . . . . . . . . . 6
3. Status Code Definitions . . . . . . . . . . . . . . . . . . . 7
3.1. 206 Partial Content . . . . . . . . . . . . . . . . . . . 7
3.2. 416 Requested Range Not Satisfiable . . . . . . . . . . . 8
4. Combining Ranges . . . . . . . . . . . . . . . . . . . . . . . 8
5. Header Field Definitions . . . . . . . . . . . . . . . . . . . 8
5.1. Accept-Ranges . . . . . . . . . . . . . . . . . . . . . . 9
5.2. Content-Range . . . . . . . . . . . . . . . . . . . . . . 9
5.3. If-Range . . . . . . . . . . . . . . . . . . . . . . . . . 11
5.4. Range . . . . . . . . . . . . . . . . . . . . . . . . . . 12
5.4.1. Byte Ranges . . . . . . . . . . . . . . . . . . . . . 12
5.4.2. Range Retrieval Requests . . . . . . . . . . . . . . . 14
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15
6.1. Status Code Registration . . . . . . . . . . . . . . . . . 15
6.2. Header Field Registration . . . . . . . . . . . . . . . . 15
6.3. Range Specifier Registration . . . . . . . . . . . . . . . 16
7. Security Considerations . . . . . . . . . . . . . . . . . . . 16
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 16
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 16
9.1. Normative References . . . . . . . . . . . . . . . . . . . 16
9.2. Informative References . . . . . . . . . . . . . . . . . . 17
Appendix A. Internet Media Type multipart/byteranges . . . . . . 17
Appendix B. Compatibility with Previous Versions . . . . . . . . 20
B.1. Changes from RFC 2616 . . . . . . . . . . . . . . . . . . 20
Appendix C. Collected ABNF . . . . . . . . . . . . . . . . . . . 20
Appendix D. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 21
D.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 21
D.2. Since draft-ietf-httpbis-p5-range-00 . . . . . . . . . . . 21
D.3. Since draft-ietf-httpbis-p5-range-01 . . . . . . . . . . . 22
D.4. Since draft-ietf-httpbis-p5-range-02 . . . . . . . . . . . 22
D.5. Since draft-ietf-httpbis-p5-range-03 . . . . . . . . . . . 22
D.6. Since draft-ietf-httpbis-p5-range-04 . . . . . . . . . . . 22
D.7. Since draft-ietf-httpbis-p5-range-05 . . . . . . . . . . . 22
D.8. Since draft-ietf-httpbis-p5-range-06 . . . . . . . . . . . 23
D.9. Since draft-ietf-httpbis-p5-range-07 . . . . . . . . . . . 23
D.10. Since draft-ietf-httpbis-p5-range-08 . . . . . . . . . . . 23
D.11. Since draft-ietf-httpbis-p5-range-09 . . . . . . . . . . . 23
D.12. Since draft-ietf-httpbis-p5-range-10 . . . . . . . . . . . 23
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Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
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1. Introduction
HTTP clients often encounter interrupted data transfers as a result
of cancelled requests or dropped connections. When a cache has
stored a partial representation, it is desirable to request the
remainder of that representation in a subsequent request rather than
transfer the entire representation. There are also a number of Web
applications that benefit from being able to request only a subset of
a larger representation, such as a single page of a very large
document or only part of an image to be rendered by a device with
limited local storage.
This document defines HTTP/1.1 range requests, partial responses, and
the multipart/byteranges media type. The protocol for range requests
is an OPTIONAL feature of HTTP, designed so resources or recipients
that do not implement this feature can respond as if it is a normal
GET request without impacting interoperability. Partial responses
are indicated by a distinct status code to not be mistaken for full
responses by intermediate caches that might not implement the
feature.
Although the HTTP range request mechanism is designed to allow for
extensible range types, this specification only defines requests for
byte ranges.
1.1. Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
An implementation is not compliant if it fails to satisfy one or more
of the "MUST" or "REQUIRED" level requirements for the protocols it
implements. An implementation that satisfies all the "MUST" or
"REQUIRED" level and all the "SHOULD" level requirements for its
protocols is said to be "unconditionally compliant"; one that
satisfies all the "MUST" level requirements but not all the "SHOULD"
level requirements for its protocols is said to be "conditionally
compliant".
1.2. Syntax Notation
This specification uses the ABNF syntax defined in Section 1.2 of
[Part1] (which extends the syntax defined in [RFC5234] with a list
rule). Appendix C shows the collected ABNF, with the list rule
expanded.
The following core rules are included by reference, as defined in
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[RFC5234], Appendix B.1: ALPHA (letters), CR (carriage return), CRLF
(CR LF), CTL (controls), DIGIT (decimal 0-9), DQUOTE (double quote),
HEXDIG (hexadecimal 0-9/A-F/a-f), LF (line feed), OCTET (any 8-bit
sequence of data), SP (space), VCHAR (any visible USASCII character),
and WSP (whitespace).
1.2.1. Core Rules
The core rules below are defined in Section 1.2.2 of [Part1]:
token = <token, defined in [Part1], Section 1.2.2>
OWS = <OWS, defined in [Part1], Section 1.2.2>
1.2.2. ABNF Rules defined in other Parts of the Specification
The ABNF rules below are defined in other parts:
HTTP-date = <HTTP-date, defined in [Part1], Section 6.1>
entity-tag = <entity-tag, defined in [Part4], Section 2>
2. Range Units
HTTP/1.1 allows a client to request that only part (a range of) the
representation be included within the response. HTTP/1.1 uses range
units in the Range (Section 5.4) and Content-Range (Section 5.2)
header fields. A representation can be broken down into subranges
according to various structural units.
range-unit = bytes-unit / other-range-unit
bytes-unit = "bytes"
other-range-unit = token
HTTP/1.1 has been designed to allow implementations of applications
that do not depend on knowledge of ranges. The only range unit
defined by HTTP/1.1 is "bytes". Additional specifiers can be defined
as described in Section 2.1.
If a range unit is not understood in a request, a server MUST ignore
the whole Range header (Section 5.4). If a range unit is not
understood in a response, an intermediary SHOULD pass the response to
the client; a client MUST fail.
2.1. Range Specifier Registry
The HTTP Ranger Specifier Registry defines the name space for the
range specifier names.
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Registrations MUST include the following fields:
o Name
o Description
o Pointer to specification text
Values to be added to this name space are subject to IETF review
([RFC5226], Section 4.1).
The registry itself is maintained at
<http://www.iana.org/assignments/http-range-specifiers>.
3. Status Code Definitions
3.1. 206 Partial Content
The server has fulfilled the partial GET request for the resource.
The request MUST have included a Range header field (Section 5.4)
indicating the desired range, and MAY have included an If-Range
header field (Section 5.3) to make the request conditional.
The response MUST include the following header fields:
o Either a Content-Range header field (Section 5.2) indicating the
range included with this response, or a multipart/byteranges
Content-Type including Content-Range fields for each part. If a
Content-Length header field is present in the response, its value
MUST match the actual number of octets transmitted in the message-
body.
o Date
o Cache-Control, ETag, Expires, Content-Location, Last-Modified,
and/or Vary, if the header field would have been sent in a 200
response to the same request
If the 206 response is the result of an If-Range request, the
response SHOULD NOT include other representation header fields.
Otherwise, the response MUST include all of the representation header
fields that would have been returned with a 200 (OK) response to the
same request.
A cache MUST NOT combine a 206 response with other previously cached
content if the ETag or Last-Modified headers do not match exactly,
see Section 4.
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A cache that does not support the Range and Content-Range headers
MUST NOT cache 206 (Partial Content) responses. Furthermore, if a
response uses a range unit that is not understood by the cache, then
it MUST NOT be cached either.
3.2. 416 Requested Range Not Satisfiable
A server SHOULD return a response with this status code if a request
included a Range request-header field (Section 5.4), and none of the
ranges-specifier values in this field overlap the current extent of
the selected resource, and the request did not include an If-Range
request-header field (Section 5.3). (For byte-ranges, this means
that the first-byte-pos of all of the byte-range-spec values were
greater than the current length of the selected resource.)
When this status code is returned for a byte-range request, the
response SHOULD include a Content-Range header field specifying the
current length of the representation (see Section 5.2). This
response MUST NOT use the multipart/byteranges content-type.
4. Combining Ranges
A response might transfer only a subrange of a representation, either
because the request included one or more Range specifications, or
because a connection closed prematurely. After several such
transfers, a cache might have received several ranges of the same
representation.
If a cache has a stored non-empty set of subranges for a
representation, and an incoming response transfers another subrange,
the cache MAY combine the new subrange with the existing set if both
the following conditions are met:
o Both the incoming response and the cache entry have a cache
validator.
o The two cache validators match using the strong comparison
function (see Section 4 of [Part4]).
If either requirement is not met, the cache MUST use only the most
recent partial response (based on the Date values transmitted with
every response, and using the incoming response if these values are
equal or missing), and MUST discard the other partial information.
5. Header Field Definitions
This section defines the syntax and semantics of HTTP/1.1 header
fields related to range requests and partial responses.
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5.1. Accept-Ranges
The "Accept-Ranges" response-header field allows a resource to
indicate its acceptance of range requests.
Accept-Ranges = "Accept-Ranges" ":" OWS Accept-Ranges-v
Accept-Ranges-v = acceptable-ranges
acceptable-ranges = 1#range-unit / "none"
Origin servers that accept byte-range requests MAY send
Accept-Ranges: bytes
but are not required to do so. Clients MAY generate range requests
without having received this header for the resource involved. Range
units are defined in Section 2.
Servers that do not accept any kind of range request for a resource
MAY send
Accept-Ranges: none
to advise the client not to attempt a range request.
5.2. Content-Range
The "Content-Range" header field is sent with a partial
representation to specify where in the full representation the
payload body is intended to be applied.
Range units are defined in Section 2.
Content-Range = "Content-Range" ":" OWS Content-Range-v
Content-Range-v = content-range-spec
content-range-spec = byte-content-range-spec
/ other-content-range-spec
byte-content-range-spec = bytes-unit SP
byte-range-resp-spec "/"
( instance-length / "*" )
byte-range-resp-spec = (first-byte-pos "-" last-byte-pos)
/ "*"
instance-length = 1*DIGIT
other-content-range-spec = other-range-unit SP
other-range-resp-spec
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other-range-resp-spec = *CHAR
The header SHOULD indicate the total length of the full
representation, unless this length is unknown or difficult to
determine. The asterisk "*" character means that the instance-length
is unknown at the time when the response was generated.
Unlike byte-ranges-specifier values (see Section 5.4.1), a byte-
range-resp-spec MUST only specify one range, and MUST contain
absolute byte positions for both the first and last byte of the
range.
A byte-content-range-spec with a byte-range-resp-spec whose last-
byte-pos value is less than its first-byte-pos value, or whose
instance-length value is less than or equal to its last-byte-pos
value, is invalid. The recipient of an invalid byte-content-range-
spec MUST ignore it and any content transferred along with it.
In the case of a byte range request: A server sending a response with
status code 416 (Requested range not satisfiable) SHOULD include a
Content-Range field with a byte-range-resp-spec of "*". The
instance-length specifies the current length of the selected
resource. A response with status code 206 (Partial Content) MUST NOT
include a Content-Range field with a byte-range-resp-spec of "*".
Examples of byte-content-range-spec values, assuming that the
representation contains a total of 1234 bytes:
o The first 500 bytes:
bytes 0-499/1234
o The second 500 bytes:
bytes 500-999/1234
o All except for the first 500 bytes:
bytes 500-1233/1234
o The last 500 bytes:
bytes 734-1233/1234
When an HTTP message includes the content of a single range (for
example, a response to a request for a single range, or to a request
for a set of ranges that overlap without any holes), this content is
transmitted with a Content-Range header, and a Content-Length header
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showing the number of bytes actually transferred. For example,
HTTP/1.1 206 Partial Content
Date: Wed, 15 Nov 1995 06:25:24 GMT
Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
Content-Range: bytes 21010-47021/47022
Content-Length: 26012
Content-Type: image/gif
When an HTTP message includes the content of multiple ranges (for
example, a response to a request for multiple non-overlapping
ranges), these are transmitted as a multipart message. The multipart
media type used for this purpose is "multipart/byteranges" as defined
in Appendix A.
A response to a request for a single range MUST NOT be sent using the
multipart/byteranges media type. A response to a request for
multiple ranges, whose result is a single range, MAY be sent as a
multipart/byteranges media type with one part. A client that cannot
decode a multipart/byteranges message MUST NOT ask for multiple
ranges in a single request.
When a client requests multiple ranges in one request, the server
SHOULD return them in the order that they appeared in the request.
If the server ignores a byte-range-spec because it is syntactically
invalid, the server SHOULD treat the request as if the invalid Range
header field did not exist. (Normally, this means return a 200
response containing the full representation).
If the server receives a request (other than one including an If-
Range request-header field) with an unsatisfiable Range request-
header field (that is, all of whose byte-range-spec values have a
first-byte-pos value greater than the current length of the selected
resource), it SHOULD return a response code of 416 (Requested range
not satisfiable) (Section 3.2).
Note: Clients cannot depend on servers to send a 416 (Requested
range not satisfiable) response instead of a 200 (OK) response for
an unsatisfiable Range request-header, since not all servers
implement this request-header.
5.3. If-Range
If a client has a partial copy of a representation in its cache, and
wishes to have an up-to-date copy of the entire representation in its
cache, it could use the Range request-header with a conditional GET
(using either or both of If-Unmodified-Since and If-Match.) However,
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if the condition fails because the representation has been modified,
the client would then have to make a second request to obtain the
entire current representation.
The "If-Range" request-header field allows a client to "short-
circuit" the second request. Informally, its meaning is "if the
representation is unchanged, send me the part(s) that I am missing;
otherwise, send me the entire new representation".
If-Range = "If-Range" ":" OWS If-Range-v
If-Range-v = entity-tag / HTTP-date
If the client has no entity-tag for a representation, but does have a
Last-Modified date, it MAY use that date in an If-Range header. (The
server can distinguish between a valid HTTP-date and any form of
entity-tag by examining no more than two characters.) The If-Range
header SHOULD only be used together with a Range header, and MUST be
ignored if the request does not include a Range header, or if the
server does not support the sub-range operation.
If the entity-tag given in the If-Range header matches the current
cache validator for the representation, then the server SHOULD
provide the specified sub-range of the representation using a 206
(Partial Content) response. If the cache validator does not match,
then the server SHOULD return the entire representation using a 200
(OK) response.
5.4. Range
5.4.1. Byte Ranges
Since all HTTP representations are transferred as sequences of bytes,
the concept of a byte range is meaningful for any HTTP
representation. (However, not all clients and servers need to
support byte-range operations.)
Byte range specifications in HTTP apply to the sequence of bytes in
the representation body (not necessarily the same as the message-
body).
A byte range operation MAY specify a single range of bytes, or a set
of ranges within a single representation.
byte-ranges-specifier = bytes-unit "=" byte-range-set
byte-range-set = 1#( byte-range-spec / suffix-byte-range-spec )
byte-range-spec = first-byte-pos "-" [ last-byte-pos ]
first-byte-pos = 1*DIGIT
last-byte-pos = 1*DIGIT
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The first-byte-pos value in a byte-range-spec gives the byte-offset
of the first byte in a range. The last-byte-pos value gives the
byte-offset of the last byte in the range; that is, the byte
positions specified are inclusive. Byte offsets start at zero.
If the last-byte-pos value is present, it MUST be greater than or
equal to the first-byte-pos in that byte-range-spec, or the byte-
range-spec is syntactically invalid. The recipient of a byte-range-
set that includes one or more syntactically invalid byte-range-spec
values MUST ignore the header field that includes that byte-range-
set.
If the last-byte-pos value is absent, or if the value is greater than
or equal to the current length of the representation body, last-byte-
pos is taken to be equal to one less than the current length of the
representation in bytes.
By its choice of last-byte-pos, a client can limit the number of
bytes retrieved without knowing the size of the representation.
suffix-byte-range-spec = "-" suffix-length
suffix-length = 1*DIGIT
A suffix-byte-range-spec is used to specify the suffix of the
representation body, of a length given by the suffix-length value.
(That is, this form specifies the last N bytes of a representation.)
If the representation is shorter than the specified suffix-length,
the entire representation is used.
If a syntactically valid byte-range-set includes at least one byte-
range-spec whose first-byte-pos is less than the current length of
the representation, or at least one suffix-byte-range-spec with a
non-zero suffix-length, then the byte-range-set is satisfiable.
Otherwise, the byte-range-set is unsatisfiable. If the byte-range-
set is unsatisfiable, the server SHOULD return a response with a 416
(Requested range not satisfiable) status code. Otherwise, the server
SHOULD return a response with a 206 (Partial Content) status code
containing the satisfiable ranges of the representation.
Examples of byte-ranges-specifier values (assuming a representation
of length 10000):
o The first 500 bytes (byte offsets 0-499, inclusive):
bytes=0-499
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o The second 500 bytes (byte offsets 500-999, inclusive):
bytes=500-999
o The final 500 bytes (byte offsets 9500-9999, inclusive):
bytes=-500
Or:
bytes=9500-
o The first and last bytes only (bytes 0 and 9999):
bytes=0-0,-1
o Several legal but not canonical specifications of the second 500
bytes (byte offsets 500-999, inclusive):
bytes=500-600,601-999
bytes=500-700,601-999
5.4.2. Range Retrieval Requests
The "Range" request-header field defines the GET method (conditional
or not) to request one or more sub-ranges of the response
representation body, instead of the entire representation body.
Range = "Range" ":" OWS Range-v
Range-v = byte-ranges-specifier
/ other-ranges-specifier
other-ranges-specifier = other-range-unit "=" other-range-set
other-range-set = 1*CHAR
A server MAY ignore the Range header. However, HTTP/1.1 origin
servers and intermediate caches ought to support byte ranges when
possible, since Range supports efficient recovery from partially
failed transfers, and supports efficient partial retrieval of large
representations.
If the server supports the Range header and the specified range or
ranges are appropriate for the representation:
o The presence of a Range header in an unconditional GET modifies
what is returned if the GET is otherwise successful. In other
words, the response carries a status code of 206 (Partial Content)
instead of 200 (OK).
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o The presence of a Range header in a conditional GET (a request
using one or both of If-Modified-Since and If-None-Match, or one
or both of If-Unmodified-Since and If-Match) modifies what is
returned if the GET is otherwise successful and the condition is
true. It does not affect the 304 (Not Modified) response returned
if the conditional is false.
In some cases, it might be more appropriate to use the If-Range
header (see Section 5.3) in addition to the Range header.
If a proxy that supports ranges receives a Range request, forwards
the request to an inbound server, and receives an entire
representation in reply, it SHOULD only return the requested range to
its client. It SHOULD store the entire received response in its
cache if that is consistent with its cache allocation policies.
6. IANA Considerations
6.1. Status Code Registration
The HTTP Status Code Registry located at
<http://www.iana.org/assignments/http-status-codes> shall be updated
with the registrations below:
+-------+---------------------------------+-------------+
| Value | Description | Reference |
+-------+---------------------------------+-------------+
| 206 | Partial Content | Section 3.1 |
| 416 | Requested Range Not Satisfiable | Section 3.2 |
+-------+---------------------------------+-------------+
6.2. Header Field Registration
The Message Header Field Registry located at <http://www.iana.org/
assignments/message-headers/message-header-index.html> shall be
updated with the permanent registrations below (see [RFC3864]):
+-------------------+----------+----------+-------------+
| Header Field Name | Protocol | Status | Reference |
+-------------------+----------+----------+-------------+
| Accept-Ranges | http | standard | Section 5.1 |
| Content-Range | http | standard | Section 5.2 |
| If-Range | http | standard | Section 5.3 |
| Range | http | standard | Section 5.4 |
+-------------------+----------+----------+-------------+
The change controller is: "IETF (iesg@ietf.org) - Internet
Engineering Task Force".
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6.3. Range Specifier Registration
The registration procedure for HTTP Range Specifiers is defined by
Section 2.1 of this document.
The HTTP Range Specifier Registry shall be created at
<http://www.iana.org/assignments/http-range-specifiers> and be
populated with the registrations below:
+----------------------+-------------------+----------------------+
| Range Specifier Name | Description | Reference |
+----------------------+-------------------+----------------------+
| bytes | a range of octets | (this specification) |
+----------------------+-------------------+----------------------+
The change controller is: "IETF (iesg@ietf.org) - Internet
Engineering Task Force".
7. Security Considerations
No additional security considerations have been identified beyond
those applicable to HTTP in general [Part1].
8. Acknowledgments
Most of the specification of ranges is based on work originally done
by Ari Luotonen and John Franks, with additional input from Steve
Zilles, Daniel W. Connolly, Roy T. Fielding, Jim Gettys, Martin
Hamilton, Koen Holtman, Shel Kaplan, Paul Leach, Alex Lopez-Ortiz,
Larry Masinter, Jeff Mogul, Lou Montulli, David W. Morris, Luigi
Rizzo, and Bill Weihl.
9. References
9.1. Normative References
[Part1] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
and J. Reschke, Ed., "HTTP/1.1, part 1: URIs, Connections,
and Message Parsing", draft-ietf-httpbis-p1-messaging-11
(work in progress), August 2010.
[Part4] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
and J. Reschke, Ed., "HTTP/1.1, part 4: Conditional
Requests", draft-ietf-httpbis-p4-conditional-11 (work in
progress), August 2010.
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[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046,
November 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC5234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008.
9.2. Informative References
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC3864] Klyne, G., Nottingham, M., and J. Mogul, "Registration
Procedures for Message Header Fields", BCP 90, RFC 3864,
September 2004.
[RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and
Registration Procedures", BCP 13, RFC 4288, December 2005.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
May 2008.
Appendix A. Internet Media Type multipart/byteranges
When an HTTP 206 (Partial Content) response message includes the
content of multiple ranges (a response to a request for multiple non-
overlapping ranges), these are transmitted as a multipart message-
body ([RFC2046], Section 5.1). The media type for this purpose is
called "multipart/byteranges". The following is to be registered
with IANA [RFC4288].
Note: Despite the name "multipart/byteranges" is not limited to
the byte ranges only.
The multipart/byteranges media type includes one or more parts, each
with its own Content-Type and Content-Range fields. The required
boundary parameter specifies the boundary string used to separate
each body-part.
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Type name: multipart
Subtype name: byteranges
Required parameters: boundary
Optional parameters: none
Encoding considerations: only "7bit", "8bit", or "binary" are
permitted
Security considerations: none
Interoperability considerations: none
Published specification: This specification (see Appendix A).
Applications that use this media type:
Additional information:
Magic number(s): none
File extension(s): none
Macintosh file type code(s): none
Person and email address to contact for further information: See
Authors Section.
Intended usage: COMMON
Restrictions on usage: none
Author/Change controller: IESG
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For example:
HTTP/1.1 206 Partial Content
Date: Wed, 15 Nov 1995 06:25:24 GMT
Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
Content-type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
--THIS_STRING_SEPARATES
Content-type: application/pdf
Content-range: bytes 500-999/8000
...the first range...
--THIS_STRING_SEPARATES
Content-type: application/pdf
Content-range: bytes 7000-7999/8000
...the second range
--THIS_STRING_SEPARATES--
Other example:
HTTP/1.1 206 Partial Content
Date: Tue, 14 Nov 1995 06:25:24 GMT
Last-Modified: Tue, 14 July 04:58:08 GMT
Content-type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
--THIS_STRING_SEPARATES
Content-type: video/example
Content-range: exampleunit 1.2-4.3/25
...the first range...
--THIS_STRING_SEPARATES
Content-type: video/example
Content-range: exampleunit 11.2-14.3/25
...the second range
--THIS_STRING_SEPARATES--
Notes:
1. Additional CRLFs MAY precede the first boundary string in the
body.
2. Although [RFC2046] permits the boundary string to be quoted, some
existing implementations handle a quoted boundary string
incorrectly.
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3. A number of browsers and servers were coded to an early draft of
the byteranges specification to use a media type of multipart/
x-byteranges, which is almost, but not quite compatible with the
version documented in HTTP/1.1.
Appendix B. Compatibility with Previous Versions
B.1. Changes from RFC 2616
Clarify that it is not ok to use a weak cache validator in a 206
response. (Section 3.1)
Clarify that multipart/byteranges can consist of a single part.
(Appendix A)
Appendix C. Collected ABNF
Accept-Ranges = "Accept-Ranges:" OWS Accept-Ranges-v
Accept-Ranges-v = acceptable-ranges
Content-Range = "Content-Range:" OWS Content-Range-v
Content-Range-v = content-range-spec
HTTP-date = <HTTP-date, defined in [Part1], Section 6.1>
If-Range = "If-Range:" OWS If-Range-v
If-Range-v = entity-tag / HTTP-date
OWS = <OWS, defined in [Part1], Section 1.2.2>
Range = "Range:" OWS Range-v
Range-v = byte-ranges-specifier / other-ranges-specifier
acceptable-ranges = ( *( "," OWS ) range-unit *( OWS "," [ OWS
range-unit ] ) ) / "none"
byte-content-range-spec = bytes-unit SP byte-range-resp-spec "/" (
instance-length / "*" )
byte-range-resp-spec = ( first-byte-pos "-" last-byte-pos ) / "*"
byte-range-set = ( *( "," OWS ) byte-range-spec ) / (
suffix-byte-range-spec *( OWS "," [ ( OWS byte-range-spec ) /
suffix-byte-range-spec ] ) )
byte-range-spec = first-byte-pos "-" [ last-byte-pos ]
byte-ranges-specifier = bytes-unit "=" byte-range-set
bytes-unit = "bytes"
content-range-spec = byte-content-range-spec /
other-content-range-spec
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entity-tag = <entity-tag, defined in [Part4], Section 2>
first-byte-pos = 1*DIGIT
instance-length = 1*DIGIT
last-byte-pos = 1*DIGIT
other-content-range-spec = other-range-unit SP other-range-resp-spec
other-range-resp-spec = *CHAR
other-range-set = 1*CHAR
other-range-unit = token
other-ranges-specifier = other-range-unit "=" other-range-set
range-unit = bytes-unit / other-range-unit
suffix-byte-range-spec = "-" suffix-length
suffix-length = 1*DIGIT
token = <token, defined in [Part1], Section 1.2.2>
ABNF diagnostics:
; Accept-Ranges defined but not used
; Content-Range defined but not used
; If-Range defined but not used
; Range defined but not used
Appendix D. Change Log (to be removed by RFC Editor before publication)
D.1. Since RFC2616
Extracted relevant partitions from [RFC2616].
D.2. Since draft-ietf-httpbis-p5-range-00
Closed issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/18>: "Cache
validators in 206 responses"
(<http://purl.org/NET/http-errata#ifrange206>)
o <http://tools.ietf.org/wg/httpbis/trac/ticket/35>: "Normative and
Informative references"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/86>: "Normative up-
to-date references"
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D.3. Since draft-ietf-httpbis-p5-range-01
Closed issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/55>: "Updating to
RFC4288"
Ongoing work on ABNF conversion
(<http://tools.ietf.org/wg/httpbis/trac/ticket/36>):
o Add explicit references to BNF syntax and rules imported from
other parts of the specification.
D.4. Since draft-ietf-httpbis-p5-range-02
Ongoing work on IANA Message Header Registration
(<http://tools.ietf.org/wg/httpbis/trac/ticket/40>):
o Reference RFC 3984, and update header registrations for headers
defined in this document.
D.5. Since draft-ietf-httpbis-p5-range-03
D.6. Since draft-ietf-httpbis-p5-range-04
Closed issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/133>: "multipart/
byteranges minimum number of parts"
Ongoing work on ABNF conversion
(<http://tools.ietf.org/wg/httpbis/trac/ticket/36>):
o Use "/" instead of "|" for alternatives.
o Introduce new ABNF rules for "bad" whitespace ("BWS"), optional
whitespace ("OWS") and required whitespace ("RWS").
o Rewrite ABNFs to spell out whitespace rules, factor out header
value format definitions.
D.7. Since draft-ietf-httpbis-p5-range-05
Closed issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/142>: "State base
for *-byte-pos and suffix-length"
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Ongoing work on Custom Ranges
(<http://tools.ietf.org/wg/httpbis/trac/ticket/85>):
o Remove bias in favor of byte ranges; allow custom ranges in ABNF.
Final work on ABNF conversion
(<http://tools.ietf.org/wg/httpbis/trac/ticket/36>):
o Add appendix containing collected and expanded ABNF, reorganize
ABNF introduction.
D.8. Since draft-ietf-httpbis-p5-range-06
Closed issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/161>: "base for
numeric protocol elements"
D.9. Since draft-ietf-httpbis-p5-range-07
Closed issues:
o Fixed discrepancy in the If-Range definition about allowed
validators.
o <http://tools.ietf.org/wg/httpbis/trac/ticket/150>: "multipart/
byteranges for custom range units"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/151>: "range unit
missing from other-ranges-specifier in Range header"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/198>: "move IANA
registrations for optional status codes"
D.10. Since draft-ietf-httpbis-p5-range-08
No significant changes.
D.11. Since draft-ietf-httpbis-p5-range-09
No significant changes.
D.12. Since draft-ietf-httpbis-p5-range-10
Closed issues:
o <http://tools.ietf.org/wg/httpbis/trac/ticket/69>: "Clarify
'Requested Variant'"
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o <http://tools.ietf.org/wg/httpbis/trac/ticket/109>: "Clarify
entity / representation / variant terminology"
o <http://tools.ietf.org/wg/httpbis/trac/ticket/220>: "consider
removing the 'changes from 2068' sections"
Ongoing work on Custom Ranges
(<http://tools.ietf.org/wg/httpbis/trac/ticket/85>):
o Add IANA registry.
Index
2
206 Partial Content (status code) 7
4
416 Requested Range Not Satisfiable (status code) 8
A
Accept-Ranges header 9
C
Content-Range header 9
G
Grammar
Accept-Ranges 9
Accept-Ranges-v 9
acceptable-ranges 9
byte-content-range-spec 9
byte-range-resp-spec 9
byte-range-set 12
byte-range-spec 12
byte-ranges-specifier 12
bytes-unit 6
Content-Range 9
content-range-spec 9
Content-Range-v 9
first-byte-pos 12
If-Range 12
If-Range-v 12
instance-length 9
last-byte-pos 12
other-range-unit 6
Range 14
range-unit 6
ranges-specifier 12
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suffix-byte-range-spec 13
suffix-length 13
H
Headers
Accept-Ranges 9
Content-Range 9
If-Range 11
Range 12
I
If-Range header 11
M
Media Type
multipart/byteranges 17
multipart/x-byteranges 20
multipart/byteranges Media Type 17
multipart/x-byteranges Media Type 20
R
Range header 12
S
Status Codes
206 Partial Content 7
416 Requested Range Not Satisfiable 8
Authors' Addresses
Roy T. Fielding (editor)
Day Software
23 Corporate Plaza DR, Suite 280
Newport Beach, CA 92660
USA
Phone: +1-949-706-5300
Fax: +1-949-706-5305
EMail: fielding@gbiv.com
URI: http://roy.gbiv.com/
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Jim Gettys
Alcatel-Lucent Bell Labs
21 Oak Knoll Road
Carlisle, MA 01741
USA
EMail: jg@freedesktop.org
URI: http://gettys.wordpress.com/
Jeffrey C. Mogul
Hewlett-Packard Company
HP Labs, Large Scale Systems Group
1501 Page Mill Road, MS 1177
Palo Alto, CA 94304
USA
EMail: JeffMogul@acm.org
Henrik Frystyk Nielsen
Microsoft Corporation
1 Microsoft Way
Redmond, WA 98052
USA
EMail: henrikn@microsoft.com
Larry Masinter
Adobe Systems, Incorporated
345 Park Ave
San Jose, CA 95110
USA
EMail: LMM@acm.org
URI: http://larry.masinter.net/
Paul J. Leach
Microsoft Corporation
1 Microsoft Way
Redmond, WA 98052
EMail: paulle@microsoft.com
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Tim Berners-Lee
World Wide Web Consortium
MIT Computer Science and Artificial Intelligence Laboratory
The Stata Center, Building 32
32 Vassar Street
Cambridge, MA 02139
USA
EMail: timbl@w3.org
URI: http://www.w3.org/People/Berners-Lee/
Yves Lafon (editor)
World Wide Web Consortium
W3C / ERCIM
2004, rte des Lucioles
Sophia-Antipolis, AM 06902
France
EMail: ylafon@w3.org
URI: http://www.raubacapeu.net/people/yves/
Julian F. Reschke (editor)
greenbytes GmbH
Hafenweg 16
Muenster, NW 48155
Germany
Phone: +49 251 2807760
Fax: +49 251 2807761
EMail: julian.reschke@greenbytes.de
URI: http://greenbytes.de/tech/webdav/
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