Network Working Group R. Fielding Request for Comments: 2616 ...

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yte-ranges-specifier = bytes-unit "=" byte-range-setbyte-range-set = 1#( byte-range-spec | suffix-byte-range-spec )byte-range-spec = first-byte-pos "-" [last-byte-pos]first-byte-pos = 1*DIGITlast-byte-pos = 1*DIGITThe first-byte-pos value in a byte-range-spec gives the byte-offsetof the first byte in a range. The last-byte-pos value gives thebyte-offset of the last byte in the range; that is, the bytepositions specified are inclusive. Byte offsets start at zero.If the last-byte-pos value is present, it MUST be greater than orequal to the first-byte-pos in that byte-range-spec, or the byterange-specis syntactically invalid. The recipient of a byte-rangesetthat includes one or more syntactically invalid byte-range-specvalues MUST ignore the header field that includes that byte-rangeset.If the last-byte-pos value is absent, or if the value is greater thanor equal to the current length of the entity-body, last-byte-pos istaken to be equal to one less than the current length of the entitybodyin bytes.By its choice of last-byte-pos, a client can limit the number ofbytes retrieved without knowing the size of the entity.Fielding, et al. Standards Track [Page 138]RFC 2616 HTTP/1.1 June 1999suffix-byte-range-spec = "-" suffix-lengthsuffix-length = 1*DIGITA suffix-byte-range-spec is used to specify the suffix of theentity-body, of a length given by the suffix-length value. (That is,this form specifies the last N bytes of an entity-body.) If theentity is shorter than the specified suffix-length, the entireentity-body is used.If a syntactically valid byte-range-set includes at least one byterange-specwhose first-byte-pos is less than the current length ofthe entity-body, or at least one suffix-byte-range-spec with a nonzerosuffix-length, then the byte-range-set is satisfiable.Otherwise, the byte-range-set is unsatisfiable. If the byte-range-setis unsatisfiable, the server SHOULD return a response with a statusof 416 (Requested range not satisfiable). Otherwise, the serverSHOULD return a response with a status of 206 (Partial Content)
containing the satisfiable ranges of the entity-body.Examples of byte-ranges-specifier values (assuming an entity-body oflength 10000):- The first 500 bytes (byte offsets 0-499, inclusive): bytes=0-499- The second 500 bytes (byte offsets 500-999, inclusive):bytes=500-999- The final 500 bytes (byte offsets 9500-9999, inclusive):bytes=-500- Or bytes=9500-- The first and last bytes only (bytes 0 and 9999): bytes=0-0,-1- Several legal but not canonical specifications of the second 500bytes (byte offsets 500-999, inclusive):bytes=500-600,601-999bytes=500-700,601-99914.35.2 Range Retrieval RequestsHTTP retrieval requests using conditional or unconditional GETmethods MAY request one or more sub-ranges of the entity, instead ofthe entire entity, using the Range request header, which applies tothe entity returned as the result of the request:Range = "Range" ":" ranges-specifierFielding, et al. Standards Track [Page 139]RFC 2616 HTTP/1.1 June 1999A server MAY ignore the Range header. However, HTTP/1.1 originservers and intermediate caches ought to support byte ranges whenpossible, since Range supports efficient recovery from partiallyfailed transfers, and supports efficient partial retrieval of largeentities.If the server supports the Range header and the specified range orranges are appropriate for the entity:- The presence of a Range header in an unconditional GET modifieswhat is returned if the GET is otherwise successful. In otherwords, the response carries a status code of 206 (Partial
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eferred to as "HTTP/1.1", and is an
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12.1 Server-driven Negotiation ....
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14.40 Trailer .....................
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1.2 RequirementsThe key words "MUST
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Fielding, et al. Standards Track [P
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equest chain ----------------------
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Elements separated by a bar ("|") a
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HTTP/1.1 header field values can be
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An application that sends a request
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3.2.3 URI ComparisonWhen comparing
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is not desirable and is discouraged
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CRLFchunk = chunk-size [ chunk-exte
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When in canonical form, media subty
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3.9 Quality ValuesHTTP content nego
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RFC 2616 HTTP/1.1 June 1999HTTP/1.1
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message-body = entity-body| Transfe
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in advance.Messages MUST NOT includ
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equested resource, and 501 (Not Imp
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names) MUST use the following rules
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values for the first digit:- 1xx: I
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how the transfer-length of a messag
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connection-token close.If either th
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idempotent (see section 9.1.2). Non
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compatibility with RFC 2068, a serv
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If at any point an error status is
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optional features implemented by th
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- Extending a database through an a
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intervention (or other means) on th
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10.1.2 101 Switching ProtocolsThe s
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esponse MAY include new or updated
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The response MUST include the follo
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If the client is sending data, a se
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If the response could be unacceptab
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10.4.15 414 Request-URI Too LongThe
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10.5.5 504 Gateway TimeoutThe serve
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Caching would be useless if it did
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Warning (but without removing any e
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If the user has overridden the basi
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in the past. This means that the re
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RFC 2616 HTTP/1.1 June 1999the time
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simple:response_is_fresh = (freshne
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match.In HTTP/1.1, a conditional re
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validators or strong validators. Cl
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- MAY send a weak entity tag instea
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Unless specifically constrained by
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Page 110 and 111: The Accept request-header field can
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Page 120 and 121: - Restrictions on what may be store
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Page 132 and 133: 14.14 Content-LocationThe Content-L
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Page 146 and 147: RFC 2616 HTTP/1.1 June 1999If none
Page 148 and 149: 14.29 Last-ModifiedThe Last-Modifie
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Page 182 and 183: Notes:1) Additional CRLFs may prece
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Network Working Group R. Fielding Request for Comments: 2616 ...

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