draft-ietf-httpbis-p5-range-01.txt   draft-ietf-httpbis-p5-range-02.txt 
Network Working Group R. Fielding, Ed. Network Working Group R. Fielding, Ed.
Internet-Draft Day Software Internet-Draft Day Software
Obsoletes: 2616 (if approved) J. Gettys Obsoletes: 2616 (if approved) J. Gettys
Intended status: Standards Track One Laptop per Child Intended status: Standards Track One Laptop per Child
Expires: July 15, 2008 J. Mogul Expires: August 27, 2008 J. Mogul
HP HP
H. Frystyk H. Frystyk
Microsoft Microsoft
L. Masinter L. Masinter
Adobe Systems Adobe Systems
P. Leach P. Leach
Microsoft Microsoft
T. Berners-Lee T. Berners-Lee
W3C/MIT W3C/MIT
Y. Lafon, Ed. Y. Lafon, Ed.
W3C W3C
J. Reschke, Ed. J. Reschke, Ed.
greenbytes greenbytes
January 12, 2008 February 24, 2008
HTTP/1.1, part 5: Range Requests and Partial Responses HTTP/1.1, part 5: Range Requests and Partial Responses
draft-ietf-httpbis-p5-range-01 draft-ietf-httpbis-p5-range-02
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on July 15, 2008. This Internet-Draft will expire on August 27, 2008.
Copyright Notice Copyright Notice
Copyright (C) The IETF Trust (2008). Copyright (C) The IETF Trust (2008).
Abstract Abstract
The Hypertext Transfer Protocol (HTTP) is an application-level The Hypertext Transfer Protocol (HTTP) is an application-level
protocol for distributed, collaborative, hypermedia information protocol for distributed, collaborative, hypermedia information
systems. HTTP has been in use by the World Wide Web global systems. HTTP has been in use by the World Wide Web global
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This draft incorporates those issue resolutions that were either This draft incorporates those issue resolutions that were either
collected in the original RFC2616 errata list collected in the original RFC2616 errata list
(<http://purl.org/NET/http-errata>), or which were agreed upon on the (<http://purl.org/NET/http-errata>), or which were agreed upon on the
mailing list between October 2006 and November 2007 (as published in mailing list between October 2006 and November 2007 (as published in
"draft-lafon-rfc2616bis-03"). "draft-lafon-rfc2616bis-03").
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Requirements . . . . . . . . . . . . . . . . . . . . . . . 4
2. Range Units . . . . . . . . . . . . . . . . . . . . . . . . . 4 2. Notational Conventions and Generic Grammar . . . . . . . . . . 4
3. Status Code Definitions . . . . . . . . . . . . . . . . . . . 5 3. Range Units . . . . . . . . . . . . . . . . . . . . . . . . . 5
3.1. 206 Partial Content . . . . . . . . . . . . . . . . . . . 5 4. Status Code Definitions . . . . . . . . . . . . . . . . . . . 5
3.2. 416 Requested Range Not Satisfiable . . . . . . . . . . . 6 4.1. 206 Partial Content . . . . . . . . . . . . . . . . . . . 5
4. Combining Byte Ranges . . . . . . . . . . . . . . . . . . . . 6 4.2. 416 Requested Range Not Satisfiable . . . . . . . . . . . 6
5. Header Field Definitions . . . . . . . . . . . . . . . . . . . 6 5. Combining Byte Ranges . . . . . . . . . . . . . . . . . . . . 6
5.1. Accept-Ranges . . . . . . . . . . . . . . . . . . . . . . 7 6. Header Field Definitions . . . . . . . . . . . . . . . . . . . 7
5.2. Content-Range . . . . . . . . . . . . . . . . . . . . . . 7 6.1. Accept-Ranges . . . . . . . . . . . . . . . . . . . . . . 7
5.3. If-Range . . . . . . . . . . . . . . . . . . . . . . . . . 9 6.2. Content-Range . . . . . . . . . . . . . . . . . . . . . . 8
5.4. Range . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6.3. If-Range . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.4.1. Byte Ranges . . . . . . . . . . . . . . . . . . . . . 10 6.4. Range . . . . . . . . . . . . . . . . . . . . . . . . . . 10
5.4.2. Range Retrieval Requests . . . . . . . . . . . . . . . 12 6.4.1. Byte Ranges . . . . . . . . . . . . . . . . . . . . . 10
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 6.4.2. Range Retrieval Requests . . . . . . . . . . . . . . . 12
7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13 8. Security Considerations . . . . . . . . . . . . . . . . . . . 13
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 13
9.1. Normative References . . . . . . . . . . . . . . . . . . . 13 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
9.2. Informative References . . . . . . . . . . . . . . . . . . 14 10.1. Normative References . . . . . . . . . . . . . . . . . . . 13
10.2. Informative References . . . . . . . . . . . . . . . . . . 14
Appendix A. Internet Media Type multipart/byteranges . . . . . . 14 Appendix A. Internet Media Type multipart/byteranges . . . . . . 14
Appendix B. Compatibility with Previous Versions . . . . . . . . 15 Appendix B. Compatibility with Previous Versions . . . . . . . . 16
B.1. Changes from RFC 2068 . . . . . . . . . . . . . . . . . . 15 B.1. Changes from RFC 2068 . . . . . . . . . . . . . . . . . . 16
B.2. Changes from RFC 2616 . . . . . . . . . . . . . . . . . . 16 B.2. Changes from RFC 2616 . . . . . . . . . . . . . . . . . . 17
Appendix C. Change Log (to be removed by RFC Editor before Appendix C. Change Log (to be removed by RFC Editor before
publication) . . . . . . . . . . . . . . . . . . . . 16 publication) . . . . . . . . . . . . . . . . . . . . 17
C.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 16 C.1. Since RFC2616 . . . . . . . . . . . . . . . . . . . . . . 17
C.2. Since draft-ietf-httpbis-p5-range-00 . . . . . . . . . . . 16 C.2. Since draft-ietf-httpbis-p5-range-00 . . . . . . . . . . . 17
Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 C.3. Since draft-ietf-httpbis-p5-range-01 . . . . . . . . . . . 17
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 18 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
Intellectual Property and Copyright Statements . . . . . . . . . . 21 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 19
Intellectual Property and Copyright Statements . . . . . . . . . . 22
1. Introduction 1. Introduction
HTTP clients often encounter interrupted data transfers as a result HTTP clients often encounter interrupted data transfers as a result
of cancelled requests or dropped connections. When a cache has of cancelled requests or dropped connections. When a cache has
stored a partial representation, it is desirable to request the stored a partial representation, it is desirable to request the
remainder of that representation in a subsequent request rather than remainder of that representation in a subsequent request rather than
transfer the entire representation. There are also a number of Web transfer the entire representation. There are also a number of Web
applications that benefit from being able to request only a subset of applications that benefit from being able to request only a subset of
a larger representation, such as a single page of a very large a larger representation, such as a single page of a very large
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An implementation is not compliant if it fails to satisfy one or more An implementation is not compliant if it fails to satisfy one or more
of the MUST or REQUIRED level requirements for the protocols it of the MUST or REQUIRED level requirements for the protocols it
implements. An implementation that satisfies all the MUST or implements. An implementation that satisfies all the MUST or
REQUIRED level and all the SHOULD level requirements for its REQUIRED level and all the SHOULD level requirements for its
protocols is said to be "unconditionally compliant"; one that protocols is said to be "unconditionally compliant"; one that
satisfies all the MUST level requirements but not all the SHOULD satisfies all the MUST level requirements but not all the SHOULD
level requirements for its protocols is said to be "conditionally level requirements for its protocols is said to be "conditionally
compliant." compliant."
2. Range Units 2. Notational Conventions and Generic Grammar
This specification uses the ABNF syntax defined in Section 2.1 of
[Part1] and the core rules defined in Section 2.2 of [Part1]:
[[abnf.dep: ABNF syntax and basic rules will be adopted from RFC
5234, see <http://tools.ietf.org/wg/httpbis/trac/ticket/36>.]]
DIGIT = <DIGIT, defined in [Part1], Section 2.2>
SP = <SP, defined in [Part1], Section 2.2>
token = <token, defined in [Part1], Section 2.2>
The ABNF rules below are defined in other parts:
HTTP-date = <HTTP-date, defined in [Part1], Section 3.3.1>
entity-tag = <entity-tag, defined in [Part4], Section 3>
3. Range Units
HTTP/1.1 allows a client to request that only part (a range of) the HTTP/1.1 allows a client to request that only part (a range of) the
response entity be included within the response. HTTP/1.1 uses range response entity be included within the response. HTTP/1.1 uses range
units in the Range (Section 5.4) and Content-Range (Section 5.2) units in the Range (Section 6.4) and Content-Range (Section 6.2)
header fields. An entity can be broken down into subranges according header fields. An entity can be broken down into subranges according
to various structural units. to various structural units.
range-unit = bytes-unit | other-range-unit range-unit = bytes-unit | other-range-unit
bytes-unit = "bytes" bytes-unit = "bytes"
other-range-unit = token other-range-unit = token
The only range unit defined by HTTP/1.1 is "bytes". HTTP/1.1 The only range unit defined by HTTP/1.1 is "bytes". HTTP/1.1
implementations MAY ignore ranges specified using other units. implementations MAY ignore ranges specified using other units.
HTTP/1.1 has been designed to allow implementations of applications HTTP/1.1 has been designed to allow implementations of applications
that do not depend on knowledge of ranges. that do not depend on knowledge of ranges.
3. Status Code Definitions 4. Status Code Definitions
3.1. 206 Partial Content 4.1. 206 Partial Content
The server has fulfilled the partial GET request for the resource. The server has fulfilled the partial GET request for the resource.
The request MUST have included a Range header field (Section 5.4) The request MUST have included a Range header field (Section 6.4)
indicating the desired range, and MAY have included an If-Range indicating the desired range, and MAY have included an If-Range
header field (Section 5.3) to make the request conditional. header field (Section 6.3) to make the request conditional.
The response MUST include the following header fields: The response MUST include the following header fields:
o Either a Content-Range header field (Section 5.2) indicating the o Either a Content-Range header field (Section 6.2) indicating the
range included with this response, or a multipart/byteranges range included with this response, or a multipart/byteranges
Content-Type including Content-Range fields for each part. If a Content-Type including Content-Range fields for each part. If a
Content-Length header field is present in the response, its value Content-Length header field is present in the response, its value
MUST match the actual number of OCTETs transmitted in the message- MUST match the actual number of OCTETs transmitted in the message-
body. body.
o Date o Date
o ETag and/or Content-Location, if the header would have been sent o ETag and/or Content-Location, if the header would have been sent
in a 200 response to the same request in a 200 response to the same request
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differ from that sent in any previous response for the same differ from that sent in any previous response for the same
variant variant
If the 206 response is the result of an If-Range request, the If the 206 response is the result of an If-Range request, the
response SHOULD NOT include other entity-headers. Otherwise, the response SHOULD NOT include other entity-headers. Otherwise, the
response MUST include all of the entity-headers that would have been response MUST include all of the entity-headers that would have been
returned with a 200 (OK) response to the same request. returned with a 200 (OK) response to the same request.
A cache MUST NOT combine a 206 response with other previously cached A cache MUST NOT combine a 206 response with other previously cached
content if the ETag or Last-Modified headers do not match exactly, content if the ETag or Last-Modified headers do not match exactly,
see Section 4. see Section 5.
A cache that does not support the Range and Content-Range headers A cache that does not support the Range and Content-Range headers
MUST NOT cache 206 (Partial Content) responses. MUST NOT cache 206 (Partial Content) responses.
3.2. 416 Requested Range Not Satisfiable 4.2. 416 Requested Range Not Satisfiable
A server SHOULD return a response with this status code if a request 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 included a Range request-header field (Section 6.4), and none of the
range-specifier values in this field overlap the current extent of range-specifier values in this field overlap the current extent of
the selected resource, and the request did not include an If-Range the selected resource, and the request did not include an If-Range
request-header field. (For byte-ranges, this means that the first- request-header field. (For byte-ranges, this means that the first-
byte-pos of all of the byte-range-spec values were greater than the byte-pos of all of the byte-range-spec values were greater than the
current length of the selected resource.) current length of the selected resource.)
When this status code is returned for a byte-range request, the When this status code is returned for a byte-range request, the
response SHOULD include a Content-Range entity-header field response SHOULD include a Content-Range entity-header field
specifying the current length of the selected resource (see specifying the current length of the selected resource (see
Section 5.2). This response MUST NOT use the multipart/byteranges Section 6.2). This response MUST NOT use the multipart/byteranges
content-type. content-type.
4. Combining Byte Ranges 5. Combining Byte Ranges
A response might transfer only a subrange of the bytes of an entity- A response might transfer only a subrange of the bytes of an entity-
body, either because the request included one or more Range body, either because the request included one or more Range
specifications, or because a connection was broken prematurely. specifications, or because a connection was broken prematurely.
After several such transfers, a cache might have received several After several such transfers, a cache might have received several
ranges of the same entity-body. ranges of the same entity-body.
If a cache has a stored non-empty set of subranges for an entity, and If a cache has a stored non-empty set of subranges for an entity, and
an incoming response transfers another subrange, the cache MAY an incoming response transfers another subrange, the cache MAY
combine the new subrange with the existing set if both the following combine the new subrange with the existing set if both the following
conditions are met: conditions are met:
o Both the incoming response and the cache entry have a cache o Both the incoming response and the cache entry have a cache
validator. validator.
o The two cache validators match using the strong comparison o The two cache validators match using the strong comparison
function (see Section 4 of [Part4]). function (see Section 5 of [Part4]).
If either requirement is not met, the cache MUST use only the most If either requirement is not met, the cache MUST use only the most
recent partial response (based on the Date values transmitted with recent partial response (based on the Date values transmitted with
every response, and using the incoming response if these values are every response, and using the incoming response if these values are
equal or missing), and MUST discard the other partial information. equal or missing), and MUST discard the other partial information.
5. Header Field Definitions 6. Header Field Definitions
This section defines the syntax and semantics of HTTP/1.1 header This section defines the syntax and semantics of HTTP/1.1 header
fields related to range requests and partial responses. fields related to range requests and partial responses.
For entity-header fields, both sender and recipient refer to either For entity-header fields, both sender and recipient refer to either
the client or the server, depending on who sends and who receives the the client or the server, depending on who sends and who receives the
entity. entity.
5.1. Accept-Ranges 6.1. Accept-Ranges
The Accept-Ranges response-header field allows the server to indicate The Accept-Ranges response-header field allows the server to indicate
its acceptance of range requests for a resource: its acceptance of range requests for a resource:
Accept-Ranges = "Accept-Ranges" ":" acceptable-ranges Accept-Ranges = "Accept-Ranges" ":" acceptable-ranges
acceptable-ranges = 1#range-unit | "none" acceptable-ranges = 1#range-unit | "none"
Origin servers that accept byte-range requests MAY send Origin servers that accept byte-range requests MAY send
Accept-Ranges: bytes Accept-Ranges: bytes
but are not required to do so. Clients MAY generate byte-range but are not required to do so. Clients MAY generate byte-range
requests without having received this header for the resource requests without having received this header for the resource
involved. Range units are defined in Section 2. involved. Range units are defined in Section 3.
Servers that do not accept any kind of range request for a resource Servers that do not accept any kind of range request for a resource
MAY send MAY send
Accept-Ranges: none Accept-Ranges: none
to advise the client not to attempt a range request. to advise the client not to attempt a range request.
5.2. Content-Range 6.2. Content-Range
The Content-Range entity-header is sent with a partial entity-body to The Content-Range entity-header is sent with a partial entity-body to
specify where in the full entity-body the partial body should be specify where in the full entity-body the partial body should be
applied. Range units are defined in Section 2. applied. Range units are defined in Section 3.
Content-Range = "Content-Range" ":" content-range-spec Content-Range = "Content-Range" ":" content-range-spec
content-range-spec = byte-content-range-spec content-range-spec = byte-content-range-spec
byte-content-range-spec = bytes-unit SP byte-content-range-spec = bytes-unit SP
byte-range-resp-spec "/" byte-range-resp-spec "/"
( instance-length | "*" ) ( instance-length | "*" )
byte-range-resp-spec = (first-byte-pos "-" last-byte-pos) byte-range-resp-spec = (first-byte-pos "-" last-byte-pos)
| "*" | "*"
instance-length = 1*DIGIT instance-length = 1*DIGIT
The header SHOULD indicate the total length of the full entity-body, The header SHOULD indicate the total length of the full entity-body,
unless this length is unknown or difficult to determine. The unless this length is unknown or difficult to determine. The
asterisk "*" character means that the instance-length is unknown at asterisk "*" character means that the instance-length is unknown at
the time when the response was generated. the time when the response was generated.
Unlike byte-ranges-specifier values (see Section 5.4.1), a byte- Unlike byte-ranges-specifier values (see Section 6.4.1), a byte-
range-resp-spec MUST only specify one range, and MUST contain range-resp-spec MUST only specify one range, and MUST contain
absolute byte positions for both the first and last byte of the absolute byte positions for both the first and last byte of the
range. range.
A byte-content-range-spec with a byte-range-resp-spec whose last- 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 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 instance-length value is less than or equal to its last-byte-pos
value, is invalid. The recipient of an invalid byte-content-range- value, is invalid. The recipient of an invalid byte-content-range-
spec MUST ignore it and any content transferred along with it. spec MUST ignore it and any content transferred along with it.
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If the server ignores a byte-range-spec because it is syntactically If the server ignores a byte-range-spec because it is syntactically
invalid, the server SHOULD treat the request as if the invalid Range invalid, the server SHOULD treat the request as if the invalid Range
header field did not exist. (Normally, this means return a 200 header field did not exist. (Normally, this means return a 200
response containing the full entity). response containing the full entity).
If the server receives a request (other than one including an If- If the server receives a request (other than one including an If-
Range request-header field) with an unsatisfiable Range request- Range request-header field) with an unsatisfiable Range request-
header field (that is, all of whose byte-range-spec values have a 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 first-byte-pos value greater than the current length of the selected
resource), it SHOULD return a response code of 416 (Requested range resource), it SHOULD return a response code of 416 (Requested range
not satisfiable) (Section 3.2). not satisfiable) (Section 4.2).
Note: clients cannot depend on servers to send a 416 (Requested Note: clients cannot depend on servers to send a 416 (Requested
range not satisfiable) response instead of a 200 (OK) response for range not satisfiable) response instead of a 200 (OK) response for
an unsatisfiable Range request-header, since not all servers an unsatisfiable Range request-header, since not all servers
implement this request-header. implement this request-header.
5.3. If-Range 6.3. If-Range
If a client has a partial copy of an entity in its cache, and wishes If a client has a partial copy of an entity in its cache, and wishes
to have an up-to-date copy of the entire entity in its cache, it to have an up-to-date copy of the entire entity in its cache, it
could use the Range request-header with a conditional GET (using could use the Range request-header with a conditional GET (using
either or both of If-Unmodified-Since and If-Match.) However, if the either or both of If-Unmodified-Since and If-Match.) However, if the
condition fails because the entity has been modified, the client condition fails because the entity has been modified, the client
would then have to make a second request to obtain the entire current would then have to make a second request to obtain the entire current
entity-body. entity-body.
The If-Range header allows a client to "short-circuit" the second The If-Range header allows a client to "short-circuit" the second
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header SHOULD only be used together with a Range header, and MUST be 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 ignored if the request does not include a Range header, or if the
server does not support the sub-range operation. server does not support the sub-range operation.
If the entity tag given in the If-Range header matches the current If the entity tag given in the If-Range header matches the current
entity tag for the entity, then the server SHOULD provide the entity tag for the entity, then the server SHOULD provide the
specified sub-range of the entity using a 206 (Partial Content) specified sub-range of the entity using a 206 (Partial Content)
response. If the entity tag does not match, then the server SHOULD response. If the entity tag does not match, then the server SHOULD
return the entire entity using a 200 (OK) response. return the entire entity using a 200 (OK) response.
5.4. Range 6.4. Range
5.4.1. Byte Ranges 6.4.1. Byte Ranges
Since all HTTP entities are represented in HTTP messages as sequences Since all HTTP entities are represented in HTTP messages as sequences
of bytes, the concept of a byte range is meaningful for any HTTP of bytes, the concept of a byte range is meaningful for any HTTP
entity. (However, not all clients and servers need to support byte- entity. (However, not all clients and servers need to support byte-
range operations.) range operations.)
Byte range specifications in HTTP apply to the sequence of bytes in Byte range specifications in HTTP apply to the sequence of bytes in
the entity-body (not necessarily the same as the message-body). the entity-body (not necessarily the same as the message-body).
A byte range operation MAY specify a single range of bytes, or a set A byte range operation MAY specify a single range of bytes, or a set
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o The second 500 bytes (byte offsets 500-999, inclusive): bytes=500- o The second 500 bytes (byte offsets 500-999, inclusive): bytes=500-
999 999
o The final 500 bytes (byte offsets 9500-9999, inclusive): bytes=- o The final 500 bytes (byte offsets 9500-9999, inclusive): bytes=-
500 500
o Or bytes=9500- o Or bytes=9500-
o The first and last bytes only (bytes 0 and 9999): bytes=0-0,-1 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 o Several legal but not canonical specifications of the second 500
bytes (byte offsets 500-999, inclusive): bytes (byte offsets 500-999, inclusive):
bytes=500-600,601-999 bytes=500-600,601-999
bytes=500-700,601-999 bytes=500-700,601-999
5.4.2. Range Retrieval Requests 6.4.2. Range Retrieval Requests
HTTP retrieval requests using conditional or unconditional GET HTTP retrieval requests using conditional or unconditional GET
methods MAY request one or more sub-ranges of the entity, instead of methods MAY request one or more sub-ranges of the entity, instead of
the entire entity, using the Range request header, which applies to the entire entity, using the Range request header, which applies to
the entity returned as the result of the request: the entity returned as the result of the request:
Range = "Range" ":" ranges-specifier Range = "Range" ":" ranges-specifier
A server MAY ignore the Range header. However, HTTP/1.1 origin A server MAY ignore the Range header. However, HTTP/1.1 origin
servers and intermediate caches ought to support byte ranges when servers and intermediate caches ought to support byte ranges when
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instead of 200 (OK). instead of 200 (OK).
o The presence of a Range header in a conditional GET (a request 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 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 or both of If-Unmodified-Since and If-Match) modifies what is
returned if the GET is otherwise successful and the condition is returned if the GET is otherwise successful and the condition is
true. It does not affect the 304 (Not Modified) response returned true. It does not affect the 304 (Not Modified) response returned
if the conditional is false. if the conditional is false.
In some cases, it might be more appropriate to use the If-Range In some cases, it might be more appropriate to use the If-Range
header (see Section 5.3) in addition to the Range header. header (see Section 6.3) in addition to the Range header.
If a proxy that supports ranges receives a Range request, forwards If a proxy that supports ranges receives a Range request, forwards
the request to an inbound server, and receives an entire entity in the request to an inbound server, and receives an entire entity in
reply, it SHOULD only return the requested range to its client. It reply, it SHOULD only return the requested range to its client. It
SHOULD store the entire received response in its cache if that is SHOULD store the entire received response in its cache if that is
consistent with its cache allocation policies. consistent with its cache allocation policies.
6. IANA Considerations 7. IANA Considerations
TBD. [[anchor2: TBD.]]
7. Security Considerations 8. Security Considerations
No additional security considerations have been identified beyond No additional security considerations have been identified beyond
those applicable to HTTP in general [Part1]. those applicable to HTTP in general [Part1].
8. Acknowledgments 9. Acknowledgments
Most of the specification of ranges is based on work originally done Most of the specification of ranges is based on work originally done
by Ari Luotonen and John Franks, with additional input from Steve by Ari Luotonen and John Franks, with additional input from Steve
Zilles, Daniel W. Connolly, Roy T. Fielding, Jim Gettys, Martin Zilles, Daniel W. Connolly, Roy T. Fielding, Jim Gettys, Martin
Hamilton, Koen Holtman, Shel Kaplan, Paul Leach, Alex Lopez-Ortiz, Hamilton, Koen Holtman, Shel Kaplan, Paul Leach, Alex Lopez-Ortiz,
Larry Masinter, Jeff Mogul, Lou Montulli, David W. Morris, Luigi Larry Masinter, Jeff Mogul, Lou Montulli, David W. Morris, Luigi
Rizzo, and Bill Weihl. Rizzo, and Bill Weihl.
9. References 10. References
9.1. Normative References 10.1. Normative References
[Part1] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H., [Part1] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed., Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
and J. Reschke, Ed., "HTTP/1.1, part 1: URIs, Connections, and J. Reschke, Ed., "HTTP/1.1, part 1: URIs, Connections,
and Message Parsing", draft-ietf-httpbis-p1-messaging-01 and Message Parsing", draft-ietf-httpbis-p1-messaging-02
(work in progress), January 2008. (work in progress), February 2008.
[Part3] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H., [Part3] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed., Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
and J. Reschke, Ed., "HTTP/1.1, part 3: Message Payload and J. Reschke, Ed., "HTTP/1.1, part 3: Message Payload
and Content Negotiation", draft-ietf-httpbis-p3-payload-01 and Content Negotiation", draft-ietf-httpbis-p3-payload-02
(work in progress), January 2008. (work in progress), February 2008.
[Part4] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H., [Part4] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed., Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
and J. Reschke, Ed., "HTTP/1.1, part 4: Conditional and J. Reschke, Ed., "HTTP/1.1, part 4: Conditional
Requests", draft-ietf-httpbis-p4-conditional-01 (work in Requests", draft-ietf-httpbis-p4-conditional-02 (work in
progress), January 2008. progress), February 2008.
[Part6] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H., [Part6] Fielding, R., Ed., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed., Masinter, L., Leach, P., Berners-Lee, T., Lafon, Y., Ed.,
and J. Reschke, Ed., "HTTP/1.1, part 6: Caching", and J. Reschke, Ed., "HTTP/1.1, part 6: Caching",
draft-ietf-httpbis-p6-cache-01 (work in progress), draft-ietf-httpbis-p6-cache-02 (work in progress),
January 2008. February 2008.
[RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail [RFC2046] Freed, N. and N. Borenstein, "Multipurpose Internet Mail
Extensions (MIME) Part Two: Media Types", RFC 2046, Extensions (MIME) Part Two: Media Types", RFC 2046,
November 1996. November 1996.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
9.2. Informative References 10.2. Informative References
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., [RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999. Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[RFC4288] Freed, N. and J. Klensin, "Media Type Specifications and
Registration Procedures", BCP 13, RFC 4288, December 2005.
Appendix A. Internet Media Type multipart/byteranges Appendix A. Internet Media Type multipart/byteranges
When an HTTP 206 (Partial Content) response message includes the When an HTTP 206 (Partial Content) response message includes the
content of multiple ranges (a response to a request for multiple non- content of multiple ranges (a response to a request for multiple non-
overlapping ranges), these are transmitted as a multipart message- overlapping ranges), these are transmitted as a multipart message-
body. The media type for this purpose is called "multipart/ body [RFC2046]. The media type for this purpose is called
byteranges". "multipart/byteranges". The following is to be registered with IANA
[RFC4288].
The multipart/byteranges media type includes two or more parts, each The multipart/byteranges media type includes two or more parts, each
with its own Content-Type and Content-Range fields. The required with its own Content-Type and Content-Range fields. The required
boundary parameter specifies the boundary string used to separate boundary parameter specifies the boundary string used to separate
each body-part. each body-part.
Media Type name: multipart Type name: multipart
Media subtype name: byteranges Subtype name: byteranges
Required parameters: boundary Required parameters: boundary
Optional parameters: none Optional parameters: none
Encoding considerations: only "7bit", "8bit", or "binary" are Encoding considerations: only "7bit", "8bit", or "binary" are
permitted permitted
Security considerations: none 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
For example: For example:
HTTP/1.1 206 Partial Content HTTP/1.1 206 Partial Content
Date: Wed, 15 Nov 1995 06:25:24 GMT Date: Wed, 15 Nov 1995 06:25:24 GMT
Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT Last-Modified: Wed, 15 Nov 1995 04:58:08 GMT
Content-type: multipart/byteranges; boundary=THIS_STRING_SEPARATES Content-type: multipart/byteranges; boundary=THIS_STRING_SEPARATES
--THIS_STRING_SEPARATES --THIS_STRING_SEPARATES
Content-type: application/pdf Content-type: application/pdf
Content-range: bytes 500-999/8000 Content-range: bytes 500-999/8000
skipping to change at page 15, line 45 skipping to change at page 16, line 45
version documented in HTTP/1.1. version documented in HTTP/1.1.
Appendix B. Compatibility with Previous Versions Appendix B. Compatibility with Previous Versions
B.1. Changes from RFC 2068 B.1. Changes from RFC 2068
Transfer-coding and message lengths all interact in ways that Transfer-coding and message lengths all interact in ways that
required fixing exactly when chunked encoding is used (to allow for required fixing exactly when chunked encoding is used (to allow for
transfer encoding that may not be self delimiting); it was important transfer encoding that may not be self delimiting); it was important
to straighten out exactly how message lengths are computed. to straighten out exactly how message lengths are computed.
(Section 5.2, see also [Part1], [Part3] and [Part6]) (Section 6.2, see also [Part1], [Part3] and [Part6])
There are situations where a server (especially a proxy) does not There are situations where a server (especially a proxy) does not
know the full length of a response but is capable of serving a know the full length of a response but is capable of serving a
byterange request. We therefore need a mechanism to allow byteranges byterange request. We therefore need a mechanism to allow byteranges
with a content-range not indicating the full length of the message. with a content-range not indicating the full length of the message.
(Section 5.2) (Section 6.2)
Range request responses would become very verbose if all meta-data Range request responses would become very verbose if all meta-data
were always returned; by allowing the server to only send needed were always returned; by allowing the server to only send needed
headers in a 206 response, this problem can be avoided. (Section 3.1 headers in a 206 response, this problem can be avoided. (Section 4.1
and 5.3) and 6.3)
Fix problem with unsatisfiable range requests; there are two cases: Fix problem with unsatisfiable range requests; there are two cases:
syntactic problems, and range doesn't exist in the document. The 416 syntactic problems, and range doesn't exist in the document. The 416
status code was needed to resolve this ambiguity needed to indicate status code was needed to resolve this ambiguity needed to indicate
an error for a byte range request that falls outside of the actual an error for a byte range request that falls outside of the actual
contents of a document. (Section 3.2, 5.2) contents of a document. (Section 4.2, 6.2)
B.2. Changes from RFC 2616 B.2. Changes from RFC 2616
Clarify that it is not ok to use a weak cache validator in a 206 Clarify that it is not ok to use a weak cache validator in a 206
response. (Section 3.1) response. (Section 4.1)
Appendix C. Change Log (to be removed by RFC Editor before publication) Appendix C. Change Log (to be removed by RFC Editor before publication)
C.1. Since RFC2616 C.1. Since RFC2616
Extracted relevant partitions from [RFC2616]. Extracted relevant partitions from [RFC2616].
C.2. Since draft-ietf-httpbis-p5-range-00 C.2. Since draft-ietf-httpbis-p5-range-00
Closed issues: Closed issues:
skipping to change at page 16, line 43 skipping to change at page 17, line 43
o <http://www3.tools.ietf.org/wg/httpbis/trac/ticket/18>: "Cache o <http://www3.tools.ietf.org/wg/httpbis/trac/ticket/18>: "Cache
validators in 206 responses" validators in 206 responses"
(<http://purl.org/NET/http-errata#ifrange206>) (<http://purl.org/NET/http-errata#ifrange206>)
o <http://www3.tools.ietf.org/wg/httpbis/trac/ticket/35>: "Normative o <http://www3.tools.ietf.org/wg/httpbis/trac/ticket/35>: "Normative
and Informative references" and Informative references"
o <http://www3.tools.ietf.org/wg/httpbis/trac/ticket/86>: "Normative o <http://www3.tools.ietf.org/wg/httpbis/trac/ticket/86>: "Normative
up-to-date references" up-to-date references"
C.3. Since draft-ietf-httpbis-p5-range-01
Closed issues:
o <http://www3.tools.ietf.org/wg/httpbis/trac/ticket/55>: "Updating
to RFC4288"
Ongoing work on ABNF conversion
(<http://www3.tools.ietf.org/wg/httpbis/trac/ticket/36>):
o Add explicit references to BNF syntax and rules imported from
other parts of the specification.
Index Index
2 2
206 Partial Content (status code) 5 206 Partial Content (status code) 5
4 4
416 Requested Range Not Satisfiable (status code) 6 416 Requested Range Not Satisfiable (status code) 6
A A
Accept-Ranges header 7 Accept-Ranges header 7
C C
Content-Range header 7 Content-Range header 8
G G
Grammar Grammar
Accept-Ranges 7 Accept-Ranges 7
acceptable-ranges 7 acceptable-ranges 7
byte-content-range-spec 7 byte-content-range-spec 8
byte-range-resp-spec 7 byte-range-resp-spec 8
byte-range-set 10 byte-range-set 11
byte-range-spec 10 byte-range-spec 11
byte-ranges-specifier 10 byte-ranges-specifier 11
bytes-unit 5 bytes-unit 5
Content-Range 7 Content-Range 8
content-range-spec 7 content-range-spec 8
first-byte-pos 10 first-byte-pos 11
If-Range 10 If-Range 10
instance-length 7 instance-length 8
last-byte-pos 10 last-byte-pos 11
other-range-unit 5 other-range-unit 5
Range 12 Range 12
range-unit 5 range-unit 5
ranges-specifier 10 ranges-specifier 11
suffix-byte-range-spec 11 suffix-byte-range-spec 11
suffix-length 11 suffix-length 11
H H
Headers Headers
Accept-Ranges 7 Accept-Ranges 7
Content-Range 7 Content-Range 8
If-Range 9 If-Range 10
Range 10 Range 10
I I
If-Range header 9 If-Range header 10
M M
Media Type Media Type
multipart/byteranges 14 multipart/byteranges 14
multipart/x-byteranges 15 multipart/x-byteranges 16
multipart/byteranges Media Type 14 multipart/byteranges Media Type 14
multipart/x-byteranges Media Type 15 multipart/x-byteranges Media Type 16
R R
Range header 10 Range header 10
S S
Status Codes Status Codes
206 Partial Content 5 206 Partial Content 5
416 Requested Range Not Satisfiable 6 416 Requested Range Not Satisfiable 6
Authors' Addresses Authors' Addresses
Roy T. Fielding (editor) Roy T. Fielding (editor)
Day Software Day Software
23 Corporate Plaza DR, Suite 280 23 Corporate Plaza DR, Suite 280
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