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

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equested resource, and 501 (Not Implemented) if the method isunrecognized or not implemented by the origin server. The methods GETand HEAD MUST be supported by all general-purpose servers. All othermethods are OPTIONAL; however, if the above methods are implemented,they MUST be implemented with the same semantics as those specifiedin section 9.5.1.2 Request-URIThe Request-URI is a Uniform Resource Identifier (section 3.2) andidentifies the resource upon which to apply the request.Request-URI= "*" | absoluteURI | abs_path | authorityThe four options for Request-URI are dependent on the nature of therequest. The asterisk "*" means that the request does not apply to aparticular resource, but to the server itself, and is only allowedwhen the method used does not necessarily apply to a resource. Oneexample would beOPTIONS * HTTP/1.1The absoluteURI form is REQUIRED when the request is being made to aproxy. The proxy is requested to forward the request or service itfrom a valid cache, and return the response. Note that the proxy MAYforward the request on to another proxy or directly to the serverFielding, et al. Standards Track [Page 36]RFC 2616 HTTP/1.1 June 1999specified by the absoluteURI. In order to avoid request loops, aproxy MUST be able to recognize all of its server names, includingany aliases, local variations, and the numeric IP address. An exampleRequest-Line would be:GET http://www.w3.org/pub/WWW/TheProject.html HTTP/1.1To allow for transition to absoluteURIs in all requests in futureversions of HTTP, all HTTP/1.1 servers MUST accept the absoluteURIform in requests, even though HTTP/1.1 clients will only generatethem in requests to proxies.The authority form is only used by the CONNECT method (section 9.9).The most common form of Request-URI is that used to identify aresource on an origin server or gateway. In this case the absolutepath of the URI MUST be transmitted (see section 3.2.1, abs_path) as
the Request-URI, and the network location of the URI (authority) MUSTbe transmitted in a Host header field. For example, a client wishingto retrieve the resource above directly from the origin server wouldcreate a TCP connection to port 80 of the host "www.w3.org" and sendthe lines:GET /pub/WWW/TheProject.html HTTP/1.1Host: www.w3.orgfollowed by the remainder of the Request. Note that the absolute pathcannot be empty; if none is present in the original URI, it MUST begiven as "/" (the server root).The Request-URI is transmitted in the format specified in section3.2.1. If the Request-URI is encoded using the "% HEX HEX" encoding[42], the origin server MUST decode the Request-URI in order toproperly interpret the request. Servers SHOULD respond to invalidRequest-URIs with an appropriate status code.A transparent proxy MUST NOT rewrite the "abs_path" part of thereceived Request-URI when forwarding it to the next inbound server,except as noted above to replace a null abs_path with "/".Note: The "no rewrite" rule prevents the proxy from changing themeaning of the request when the origin server is improperly usinga non-reserved URI character for a reserved purpose. Implementorsshould be aware that some pre-HTTP/1.1 proxies have been known torewrite the Request-URI.Fielding, et al. Standards Track [Page 37]RFC 2616 HTTP/1.1 June 19995.2 The Resource Identified by a RequestThe exact resource identified by an Internet request is determined byexamining both the Request-URI and the Host header field.An origin server that does not allow resources to differ by therequested host MAY ignore the Host header field value whendetermining the resource identified by an HTTP/1.1 request. (But seesection 19.6.1.1 for other requirements on Host support in HTTP/1.1.)An origin server that does differentiate resources based on the hostrequested (sometimes referred to as virtual hosts or vanity host
Page 2: eferred to as "HTTP/1.1", and is an
Page 5 and 6: 12.1 Server-driven Negotiation ....
Page 7 and 8: 14.40 Trailer .....................
Page 9 and 10: 1.2 RequirementsThe key words "MUST
Page 12 and 13: Fielding, et al. Standards Track [P
Page 14 and 15: equest chain ----------------------
Page 16 and 17: Elements separated by a bar ("|") a
Page 18 and 19: HTTP/1.1 header field values can be
Page 20 and 21: An application that sends a request
Page 22 and 23: 3.2.3 URI ComparisonWhen comparing
Page 26 and 27: is not desirable and is discouraged
Page 28 and 29: CRLFchunk = chunk-size [ chunk-exte
Page 30 and 31: When in canonical form, media subty
Page 32 and 33: 3.9 Quality ValuesHTTP content nego
Page 34 and 35: RFC 2616 HTTP/1.1 June 1999HTTP/1.1
Page 36 and 37: message-body = entity-body| Transfe
Page 38 and 39: in advance.Messages MUST NOT includ
Page 42 and 43: names) MUST use the following rules
Page 44 and 45: values for the first digit:- 1xx: I
Page 48 and 49: how the transfer-length of a messag
Page 50 and 51: connection-token close.If either th
Page 52 and 53: idempotent (see section 9.1.2). Non
Page 54 and 55: compatibility with RFC 2068, a serv
Page 56 and 57: If at any point an error status is
Page 58 and 59: optional features implemented by th
Page 60 and 61: - Extending a database through an a
Page 62 and 63: intervention (or other means) on th
Page 64 and 65: 10.1.2 101 Switching ProtocolsThe s
Page 66 and 67: esponse MAY include new or updated
Page 70 and 71: The response MUST include the follo
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
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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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Fielding, et al. Standards Track [P
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warn-code 1xx, which are deleted ev
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for the associated entity, its enti
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- DELETE- POSTIn order to prevent d
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The Accept request-header field can
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image/jpeg = 0.5text/html;level=2 =
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Note: If the request does not inclu
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Accept-Ranges: bytesbut are not req
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containing an Authorization field,
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- Restrictions on what may be store
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improve privacy in some cases, we c
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must-revalidateBecause a cache MAY
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understand.For example, consider a
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new coding is known to be acceptabl
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14.14 Content-LocationThe Content-L
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Note: while the definition of Conte
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server SHOULD return them in the or
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Some origin server implementations
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Expires = "Expires" ":" HTTP-dateAn
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A client MUST include a Host header
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een modified since the date given b
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RFC 2616 HTTP/1.1 June 1999If none
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14.29 Last-ModifiedThe Last-Modifie
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MAY require that behavior be consis
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yte-ranges-specifier = bytes-unit "
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Content) instead of 200 (OK).- The
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The TE request-header field indicat
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a cache cannot determine from the r
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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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