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

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The TE request-header field indicates what extension transfer-codingsit is willing to accept in the response and whether or not it iswilling to accept trailer fields in a chunked transfer-coding. Itsvalue may consist of the keyword "trailers" and/or a comma-separatedlist of extension transfer-coding names with optional acceptparameters (as described in section 3.6).TE = "TE" ":" #( t-codings )t-codings = "trailers" | ( transfer-extension [ accept-params ] )The presence of the keyword "trailers" indicates that the client iswilling to accept trailer fields in a chunked transfer-coding, asdefined in section 3.6.1. This keyword is reserved for use withtransfer-coding values even though it does not itself represent atransfer-coding.Examples of its use are:TE: deflateTE:TE: trailers, deflate;q=0.5The TE header field only applies to the immediate connection.Therefore, the keyword MUST be supplied within a Connection headerfield (section 14.10) whenever TE is present in an HTTP/1.1 message.A server tests whether a transfer-coding is acceptable, according toa TE field, using these rules:1. The "chunked" transfer-coding is always acceptable. If thekeyword "trailers" is listed, the client indicates that it iswilling to accept trailer fields in the chunked response onbehalf of itself and any downstream clients. The implication isthat, if given, the client is stating that either alldownstream clients are willing to accept trailer fields in theforwarded response, or that it will attempt to buffer theresponse on behalf of downstream recipients.Note: HTTP/1.1 does not define any means to limit the size of achunked response such that a client can be assured of bufferingthe entire response.2. If the transfer-coding being tested is one of the transfercodingslisted in the TE field, then it is acceptable unless itis accompanied by a qvalue of 0. (As defined in section 3.9, aqvalue of 0 means "not acceptable.")Fielding, et al. Standards Track [Page 142]
RFC 2616 HTTP/1.1 June 19993. If multiple transfer-codings are acceptable, then theacceptable transfer-coding with the highest non-zero qvalue ispreferred. The "chunked" transfer-coding always has a qvalueof 1.If the TE field-value is empty or if no TE field is present, the onlytransfer-coding is "chunked". A message with no transfer-coding isalways acceptable.14.40 TrailerThe Trailer general field value indicates that the given set ofheader fields is present in the trailer of a message encoded withchunked transfer-coding.Trailer = "Trailer" ":" 1#field-nameAn HTTP/1.1 message SHOULD include a Trailer header field in amessage using chunked transfer-coding with a non-empty trailer. Doingso allows the recipient to know which header fields to expect in thetrailer.If no Trailer header field is present, the trailer SHOULD NOT includeany header fields. See section 3.6.1 for restrictions on the use oftrailer fields in a "chunked" transfer-coding.Message header fields listed in the Trailer header field MUST NOTinclude the following header fields:. Transfer-Encoding. Content-Length. Trailer14.41 Transfer-EncodingThe Transfer-Encoding general-header field indicates what (if any)type of transformation has been applied to the message body in orderto safely transfer it between the sender and the recipient. Thisdiffers from the content-coding in that the transfer-coding is aproperty of the message, not of the entity.Transfer-Encoding= "Transfer-Encoding" ":" 1#transfer-codingTransfer-codings are defined in section 3.6. An example is:Transfer-Encoding: chunked
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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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warn-code 1xx, which are deleted ev
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Page 110 and 111: The Accept request-header field can
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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 126 and 127: must-revalidateBecause a cache MAY
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Page 132 and 133: 14.14 Content-LocationThe Content-L
Page 134 and 135: Note: while the definition of Conte
Page 136 and 137: server SHOULD return them in the or
Page 138 and 139: Some origin server implementations
Page 140 and 141: Expires = "Expires" ":" HTTP-dateAn
Page 142 and 143: A client MUST include a Host header
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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
Page 150 and 151: MAY require that behavior be consis
Page 152 and 153: yte-ranges-specifier = bytes-unit "
Page 154 and 155: Content) instead of 200 (OK).- The
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Page 172 and 173: The HTTP protocol has evolved consi
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Page 178 and 179: University of California, IrvineIrv
Page 182 and 183: Notes:1) Additional CRLFs may prece
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Page 188 and 189: - understand any valid response in
Page 190 and 191: CREATE had a race that required an
Page 192 and 193: also needed to be a general header,
Page 194: Fielding, et al. Standards Track [P
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Network Working Group R. Fielding Request for Comments: 2616 ...

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