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

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Content) instead of 200 (OK).- The presence of a Range header in a conditional GET (a requestusing one or both of If-Modified-Since and If-None-Match, orone or both of If-Unmodified-Since and If-Match) modifies whatis returned if the GET is otherwise successful and thecondition 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-Rangeheader (see section 14.27) in addition to the Range header.If a proxy that supports ranges receives a Range request, forwardsthe request to an inbound server, and receives an entire entity inreply, it SHOULD only return the requested range to its client. ItSHOULD store the entire received response in its cache if that isconsistent with its cache allocation policies.14.36 RefererThe Referer[sic] request-header field allows the client to specify,for the server's benefit, the address (URI) of the resource fromwhich the Request-URI was obtained (the "referrer", although theheader field is misspelled.) The Referer request-header allows aserver to generate lists of back-links to resources for interest,logging, optimized caching, etc. It also allows obsolete or mistypedlinks to be traced for maintenance. The Referer field MUST NOT besent if the Request-URI was obtained from a source that does not haveits own URI, such as input from the user keyboard.Referer = "Referer" ":" ( absoluteURI | relativeURI )Example:Referer: http://www.w3.org/hypertext/DataSources/Overview.htmlFielding, et al. Standards Track [Page 140]RFC 2616 HTTP/1.1 June 1999If the field value is a relative URI, it SHOULD be interpretedrelative to the Request-URI. The URI MUST NOT include a fragment. Seesection 15.1.3 for security considerations.14.37 Retry-AfterThe Retry-After response-header field can be used with a 503 (Service
Unavailable) response to indicate how long the service is expected tobe unavailable to the requesting client. This field MAY also be usedwith any 3xx (Redirection) response to indicate the minimum time theuser-agent is asked wait before issuing the redirected request. Thevalue of this field can be either an HTTP-date or an integer numberof seconds (in decimal) after the time of the response.Retry-After = "Retry-After" ":" ( HTTP-date | delta-seconds )Two examples of its use areRetry-After: Fri, 31 Dec 1999 23:59:59 GMTRetry-After: 120In the latter example, the delay is 2 minutes.14.38 ServerThe Server response-header field contains information about thesoftware used by the origin server to handle the request. The fieldcan contain multiple product tokens (section 3.8) and commentsidentifying the server and any significant subproducts. The producttokens are listed in order of their significance for identifying theapplication.Server = "Server" ":" 1*( product | comment )Example:Server: CERN/3.0 libwww/2.17If the response is being forwarded through a proxy, the proxyapplication MUST NOT modify the Server response-header. Instead, itSHOULD include a Via field (as described in section 14.45).Note: Revealing the specific software version of the server mightallow the server machine to become more vulnerable to attacksagainst software that is known to contain security holes. Serverimplementors are encouraged to make this field a configurableoption.Fielding, et al. Standards Track [Page 141]RFC 2616 HTTP/1.1 June 199914.39 TE
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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 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 112 and 113: image/jpeg = 0.5text/html;level=2 =
Page 114 and 115: Note: If the request does not inclu
Page 116 and 117: Accept-Ranges: bytesbut are not req
Page 118 and 119: containing an Authorization field,
Page 120 and 121: - Restrictions on what may be store
Page 122 and 123: improve privacy in some cases, we c
Page 124 and 125: Fielding, et al. Standards Track [P
Page 126 and 127: must-revalidateBecause a cache MAY
Page 128 and 129: understand.For example, consider a
Page 130 and 131: new coding is known to be acceptabl
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 156 and 157: The TE request-header field indicat
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Page 162 and 163: SHOULD NOT, by default, forward the
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Page 168 and 169: strongly correlated to the membersh
Page 170 and 171: serious security considerations. Co
Page 172 and 173: The HTTP protocol has evolved consi
Page 174 and 175: Protocol -- HTTP/1.0", RFC 1945, Ma
Page 176 and 177: Implementation and Analysis", RFC 1
Page 178 and 179: University of California, IrvineIrv
Page 182 and 183: Notes:1) Additional CRLFs may prece
Page 184 and 185: full compliance with the MIME proto
Page 186 and 187: ead chunk-size and CRLF}read entity
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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