Changeset 2044 for draft-ietf-httpbis/latest/p4-conditional.html
- Timestamp:
- 08/12/12 08:20:18 (10 years ago)
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draft-ietf-httpbis/latest/p4-conditional.html
r2035 r2044 449 449 } 450 450 @bottom-center { 451 content: "Expires June 1 0, 2013";451 content: "Expires June 11, 2013"; 452 452 } 453 453 @bottom-right { … … 491 491 <meta name="dct.creator" content="Reschke, J. F."> 492 492 <meta name="dct.identifier" content="urn:ietf:id:draft-ietf-httpbis-p4-conditional-latest"> 493 <meta name="dct.issued" scheme="ISO8601" content="2012-12-0 7">493 <meta name="dct.issued" scheme="ISO8601" content="2012-12-08"> 494 494 <meta name="dct.replaces" content="urn:ietf:rfc:2616"> 495 495 <meta name="dct.abstract" content="The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypertext information systems. This document defines HTTP/1.1 conditional requests, including metadata header fields for indicating state changes, request header fields for making preconditions on such state, and rules for constructing the responses to a conditional request when one or more preconditions evaluate to false."> … … 517 517 </tr> 518 518 <tr> 519 <td class="left">Expires: June 1 0, 2013</td>520 <td class="right">December 7, 2012</td>519 <td class="left">Expires: June 11, 2013</td> 520 <td class="right">December 8, 2012</td> 521 521 </tr> 522 522 </tbody> … … 545 545 in progress”. 546 546 </p> 547 <p>This Internet-Draft will expire on June 1 0, 2013.</p>547 <p>This Internet-Draft will expire on June 11, 2013.</p> 548 548 <h1><a id="rfc.copyrightnotice" href="#rfc.copyrightnotice">Copyright Notice</a></h1> 549 549 <p>Copyright © 2012 IETF Trust and the persons identified as the document authors. All rights reserved.</p> … … 1057 1057 <h2 id="rfc.section.4.1"><a href="#rfc.section.4.1">4.1</a> <a id="status.304" href="#status.304">304 Not Modified</a></h2> 1058 1058 <p id="rfc.section.4.1.p.1">The 304 status code indicates that a conditional GET request has been received and would have resulted in a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response if it were not for the fact that the condition has evaluated to false. In other words, there is no need for the server 1059 to transfer a representation of the target resource because the client's request indicates that it already has a valid representation, 1060 as indicated by the 304 response header fields, and is therefore redirecting the client to make use of that stored representation 1061 as if it were the payload of a 200 response. The 304 response <em class="bcp14">MUST NOT</em> contain a message-body, and thus is always terminated by the first empty line after the header fields. 1062 </p> 1063 <p id="rfc.section.4.1.p.2">A 304 response <em class="bcp14">MUST</em> include a <a href="p2-semantics.html#header.date" class="smpl">Date</a> header field (<a href="p2-semantics.html#header.date" title="Date">Section 8.1.1.2</a> of <a href="#Part2" id="rfc.xref.Part2.4"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) unless the origin server does not have a clock that can provide a reasonable approximation of the current time. If a <a href="p2-semantics.html#status.200" class="smpl">200 1059 to transfer a representation of the target resource because the request indicates that the client which made the request conditional 1060 already has a valid representation; the server is therefore redirecting that client to make use of that stored representation 1061 as if it were the payload of a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response. 1062 </p> 1063 <p id="rfc.section.4.1.p.2">The 304 response <em class="bcp14">MUST NOT</em> contain a message-body, and thus is always terminated by the first empty line after the header fields. 1064 </p> 1065 <p id="rfc.section.4.1.p.3">A 304 response <em class="bcp14">MUST</em> include a <a href="p2-semantics.html#header.date" class="smpl">Date</a> header field (<a href="p2-semantics.html#header.date" title="Date">Section 8.1.1.2</a> of <a href="#Part2" id="rfc.xref.Part2.4"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) unless the origin server does not have a clock that can provide a reasonable approximation of the current time. If a <a href="p2-semantics.html#status.200" class="smpl">200 1064 1066 (OK)</a> response to the same request would have included any of the header fields <a href="p6-cache.html#header.cache-control" class="smpl">Cache-Control</a>, <a href="p2-semantics.html#header.content-location" class="smpl">Content-Location</a>, <a href="#header.etag" class="smpl">ETag</a>, <a href="p6-cache.html#header.expires" class="smpl">Expires</a>, or <a href="p2-semantics.html#header.vary" class="smpl">Vary</a>, then those same header fields <em class="bcp14">MUST</em> be sent in a 304 response. 1065 1067 </p> 1066 <p id="rfc.section.4.1.p. 3">Since the goal of a 304 response is to minimize information transfer when the recipient already has one or more cached representations,1068 <p id="rfc.section.4.1.p.4">Since the goal of a 304 response is to minimize information transfer when the recipient already has one or more cached representations, 1067 1069 the response <em class="bcp14">SHOULD NOT</em> include representation metadata other than the above listed fields unless said metadata exists for the purpose of guiding 1068 1070 cache updates (e.g., future HTTP extensions). 1069 1071 </p> 1070 <p id="rfc.section.4.1.p. 4">If the recipient of a 304 response does not have a cached representation corresponding to the entity-tag indicated by the1072 <p id="rfc.section.4.1.p.5">If the recipient of a 304 response does not have a cached representation corresponding to the entity-tag indicated by the 1071 1073 304 response, then the recipient <em class="bcp14">MUST NOT</em> use the 304 to update its own cache. If this conditional request originated with an outbound client, such as a user agent 1072 1074 with its own cache sending a conditional GET to a shared proxy, then the 304 response <em class="bcp14">MAY</em> be forwarded to that client. Otherwise, the recipient <em class="bcp14">MUST</em> disregard the 304 response and repeat the request without any preconditions. 1073 1075 </p> 1074 <p id="rfc.section.4.1.p. 5">If a cache uses a received 304 response to update a cache entry, the cache <em class="bcp14">MUST</em> update the entry to reflect any new field values given in the response.1076 <p id="rfc.section.4.1.p.6">If a cache uses a received 304 response to update a cache entry, the cache <em class="bcp14">MUST</em> update the entry to reflect any new field values given in the response. 1075 1077 </p> 1076 1078 <div id="rfc.iref.21"></div> … … 1330 1332 <a href="#header.last-modified" class="smpl">Last-Modified</a> = HTTP-date 1331 1333 1332 <a href="#imported.abnf" class="smpl">OWS</a> = <OWS, defined in [Part1], Section 3.2. 1>1334 <a href="#imported.abnf" class="smpl">OWS</a> = <OWS, defined in [Part1], Section 3.2.3> 1333 1335 1334 1336 <a href="#header.etag" class="smpl">entity-tag</a> = [ weak ] opaque-tag … … 1336 1338 / obs-text 1337 1339 1338 <a href="#imported.abnf" class="smpl">obs-text</a> = <obs-text, defined in [Part1], Section 3.2. 4>1340 <a href="#imported.abnf" class="smpl">obs-text</a> = <obs-text, defined in [Part1], Section 3.2.6> 1339 1341 <a href="#header.etag" class="smpl">opaque-tag</a> = DQUOTE *etagc DQUOTE 1340 1342
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