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

More documents

Recommendations

Info

Fielding, et al. Standards Track [Page 92]RFC 2616 HTTP/1.1 June 1999A transparent proxy MUST NOT modify any of the following fields in arequest or response, and it MUST NOT add any of these fields if notalready present:- Content-Location- Content-MD5- ETag- Last-ModifiedA transparent proxy MUST NOT modify any of the following fields in aresponse:- Expiresbut it MAY add any of these fields if not already present. If anExpires header is added, it MUST be given a field-value identical tothat of the Date header in that response.A proxy MUST NOT modify or add any of the following fields in amessage that contains the no-transform cache-control directive, or inany request:- Content-Encoding- Content-Range- Content-TypeA non-transparent proxy MAY modify or add these fields to a messagethat does not include no-transform, but if it does so, it MUST add aWarning 214 (Transformation applied) if one does not already appearin the message (see section 14.46).Warning: unnecessary modification of end-to-end headers mightcause authentication failures if stronger authenticationmechanisms are introduced in later versions of HTTP. Suchauthentication mechanisms MAY rely on the values of header fieldsnot listed here.The Content-Length field of a request or response is added or deleted
according to the rules in section 4.4. A transparent proxy MUSTpreserve the entity-length (section 7.2.2) of the entity-body,although it MAY change the transfer-length (section 4.4).Fielding, et al. Standards Track [Page 93]RFC 2616 HTTP/1.1 June 199913.5.3 Combining HeadersWhen a cache makes a validating request to a server, and the serverprovides a 304 (Not Modified) response or a 206 (Partial Content)response, the cache then constructs a response to send to therequesting client.If the status code is 304 (Not Modified), the cache uses the entitybodystored in the cache entry as the entity-body of this outgoingresponse. If the status code is 206 (Partial Content) and the ETag orLast-Modified headers match exactly, the cache MAY combine thecontents stored in the cache entry with the new contents received inthe response and use the result as the entity-body of this outgoingresponse, (see 13.5.4).The end-to-end headers stored in the cache entry are used for theconstructed response, except that- any stored Warning headers with warn-code 1xx (see section14.46) MUST be deleted from the cache entry and the forwardedresponse.- any stored Warning headers with warn-code 2xx MUST be retainedin the cache entry and the forwarded response.- any end-to-end headers provided in the 304 or 206 response MUSTreplace the corresponding headers from the cache entry.Unless the cache decides to remove the cache entry, it MUST alsoreplace the end-to-end headers stored with the cache entry withcorresponding headers received in the incoming response, except forWarning headers as described immediately above. If a header fieldnamein the incoming response matches more than one header in thecache entry, all such old headers MUST be replaced.In other words, the set of end-to-end headers received in theincoming response overrides all corresponding end-to-end headersstored with the cache entry (except for stored Warning headers with
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 24 and 25:
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 40 and 41:
equested resource, and 501 (Not Imp
Page 42 and 43:
names) MUST use the following rules
Page 44 and 45:
values for the first digit:- 1xx: I
Page 46 and 47:
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 68 and 69: Fielding, et al. Standards Track [P
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
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
Page 96 and 97: validators or strong validators. Cl
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
Page 106 and 107: for the associated entity, its enti
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 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
Page 144 and 145: een modified since the date given b
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
Page 156 and 157:
The TE request-header field indicat
Page 158 and 159:
Page 160 and 161:
a cache cannot determine from the r
Page 162 and 163:
SHOULD NOT, by default, forward the
Page 164 and 165:
this user agent behavior in mind.Re
Page 166 and 167:
designers and implementors be parti
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 180 and 181:
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:
show all

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

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?