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

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image/jpeg = 0.5text/html;level=2 = 0.4text/html;level=3 = 0.7Note: A user agent might be provided with a default set of qualityvalues for certain media ranges. However, unless the user agent isa closed system which cannot interact with other rendering agents,this default set ought to be configurable by the user.14.2 Accept-CharsetThe Accept-Charset request-header field can be used to indicate whatcharacter sets are acceptable for the response. This field allowsclients capable of understanding more comprehensive or specialpurposecharacter sets to signal that capability to a server which iscapable of representing documents in those character sets.Accept-Charset = "Accept-Charset" ":"1#( ( charset | "*" )[ ";" "q" "=" qvalue ] )Character set values are described in section 3.4. Each charset MAYbe given an associated quality value which represents the user'spreference for that charset. The default value is q=1. An example isAccept-Charset: iso-8859-5, unicode-1-1;q=0.8The special value "*", if present in the Accept-Charset field,matches every character set (including ISO-8859-1) which is notmentioned elsewhere in the Accept-Charset field. If no "*" is presentin an Accept-Charset field, then all character sets not explicitlymentioned get a quality value of 0, except for ISO-8859-1, which getsa quality value of 1 if not explicitly mentioned.If no Accept-Charset header is present, the default is that anycharacter set is acceptable. If an Accept-Charset header is present,and if the server cannot send a response which is acceptableaccording to the Accept-Charset header, then the server SHOULD sendan error response with the 406 (not acceptable) status code, thoughthe sending of an unacceptable response is also allowed.14.3 Accept-EncodingThe Accept-Encoding request-header field is similar to Accept, butrestricts the content-codings (section 3.5) that are acceptable inthe response.Accept-Encoding = "Accept-Encoding" ":"
Fielding, et al. Standards Track [Page 102]RFC 2616 HTTP/1.1 June 19991#( codings [ ";" "q" "=" qvalue ] )codings = ( content-coding | "*" )Examples of its use are:Accept-Encoding: compress, gzipAccept-Encoding:Accept-Encoding: *Accept-Encoding: compress;q=0.5, gzip;q=1.0Accept-Encoding: gzip;q=1.0, identity; q=0.5, *;q=0A server tests whether a content-coding is acceptable, according toan Accept-Encoding field, using these rules:1. If the content-coding is one of the content-codings listed inthe Accept-Encoding field, then it is acceptable, unless it isaccompanied by a qvalue of 0. (As defined in section 3.9, aqvalue of 0 means "not acceptable.")2. The special "*" symbol in an Accept-Encoding field matches anyavailable content-coding not explicitly listed in the headerfield.3. If multiple content-codings are acceptable, then the acceptablecontent-coding with the highest non-zero qvalue is preferred.4. The "identity" content-coding is always acceptable, unlessspecifically refused because the Accept-Encoding field includes"identity;q=0", or because the field includes "*;q=0" and doesnot explicitly include the "identity" content-coding. If theAccept-Encoding field-value is empty, then only the "identity"encoding is acceptable.If an Accept-Encoding field is present in a request, and if theserver cannot send a response which is acceptable according to theAccept-Encoding header, then the server SHOULD send an error responsewith the 406 (Not Acceptable) status code.If no Accept-Encoding field is present in a request, the server MAYassume that the client will accept any content coding. In this case,if "identity" is one of the available content-codings, then theserver SHOULD use the "identity" content-coding, unless it hasadditional information that a different content-coding is meaningfulto the client.
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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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Page 64 and 65: 10.1.2 101 Switching ProtocolsThe s
Page 66 and 67: esponse MAY include new or updated
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Page 72 and 73: If the client is sending data, a se
Page 74 and 75: If the response could be unacceptab
Page 76 and 77: 10.4.15 414 Request-URI Too LongThe
Page 78 and 79: 10.5.5 504 Gateway TimeoutThe serve
Page 82 and 83: Caching would be useless if it did
Page 84 and 85: Warning (but without removing any e
Page 86 and 87: If the user has overridden the basi
Page 88 and 89: in the past. This means that the re
Page 90 and 91: RFC 2616 HTTP/1.1 June 1999the time
Page 92 and 93: simple:response_is_fresh = (freshne
Page 94 and 95: match.In HTTP/1.1, a conditional re
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Page 98 and 99: - MAY send a weak entity tag instea
Page 100 and 101: Unless specifically constrained by
Page 104 and 105: warn-code 1xx, which are deleted ev
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Page 108 and 109: - DELETE- POSTIn order to prevent d
Page 110 and 111: The Accept request-header field can
Page 114 and 115: Note: If the request does not inclu
Page 116 and 117: Accept-Ranges: bytesbut are not req
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Page 120 and 121: - Restrictions on what may be store
Page 122 and 123: improve privacy in some cases, we c
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Page 128 and 129: understand.For example, consider a
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Page 132 and 133: 14.14 Content-LocationThe Content-L
Page 134 and 135: Note: while the definition of Conte
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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 154 and 155: Content) instead of 200 (OK).- The
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SHOULD NOT, by default, forward the
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this user agent behavior in mind.Re
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designers and implementors be parti
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strongly correlated to the membersh
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serious security considerations. Co
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The HTTP protocol has evolved consi
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Protocol -- HTTP/1.0", RFC 1945, Ma
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Implementation and Analysis", RFC 1
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University of California, IrvineIrv
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Notes:1) Additional CRLFs may prece
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full compliance with the MIME proto
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ead chunk-size and CRLF}read entity
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- understand any valid response in
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CREATE had a race that required an
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also needed to be a general header,
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Network Working Group R. Fielding Request for Comments: 2616 ...

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