Changeset 698 for draft-ietf-httpbis/latest/p6-cache.html
- Timestamp:
- 26/09/09 10:09:09 (13 years ago)
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draft-ietf-httpbis/latest/p6-cache.html
r697 r698 398 398 <meta name="DC.Creator" content="Reschke, J. F."> 399 399 <meta name="DC.Identifier" content="urn:ietf:id:draft-ietf-httpbis-p6-cache-latest"> 400 <meta name="DC.Date.Issued" scheme="ISO8601" content="2009-09-2 5">400 <meta name="DC.Date.Issued" scheme="ISO8601" content="2009-09-26"> 401 401 <meta name="DC.Relation.Replaces" content="urn:ietf:rfc:2616"> 402 402 <meta name="DC.Description.Abstract" content="The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypermedia information systems. This document is Part 6 of the seven-part specification that defines the protocol referred to as "HTTP/1.1" and, taken together, obsoletes RFC 2616. Part 6 defines requirements on HTTP caches and the associated header fields that control cache behavior or indicate cacheable response messages."> … … 430 430 </tr> 431 431 <tr> 432 <td class="header left">Expires: March 29, 2010</td>432 <td class="header left">Expires: March 30, 2010</td> 433 433 <td class="header right">HP</td> 434 434 </tr> … … 487 487 <tr> 488 488 <td class="header left"></td> 489 <td class="header right">September 2 5, 2009</td>489 <td class="header right">September 26, 2009</td> 490 490 </tr> 491 491 </table> … … 511 511 <p>The list of Internet-Draft Shadow Directories can be accessed at <<a href="http://www.ietf.org/shadow.html">http://www.ietf.org/shadow.html</a>>. 512 512 </p> 513 <p>This Internet-Draft will expire in March 29, 2010.</p>513 <p>This Internet-Draft will expire in March 30, 2010.</p> 514 514 <h1><a id="rfc.copyrightnotice" href="#rfc.copyrightnotice">Copyright Notice</a></h1> 515 515 <p>Copyright © 2009 IETF Trust and the persons identified as the document authors. All rights reserved.</p> … … 974 974 <div id="rfc.iref.h.2"></div> 975 975 <h2 id="rfc.section.3.1"><a href="#rfc.section.3.1">3.1</a> <a id="header.age" href="#header.age">Age</a></h2> 976 <p id="rfc.section.3.1.p.1">The "Age" response-header field conveys the sender's estimate of the amount of time since the response (or its validation)977 was generated at the origin server. Age values are calculated as specified in <a href="#age.calculations" title="Calculating Age">Section 2.3.2</a>.976 <p id="rfc.section.3.1.p.1">The "Age" response-header field conveys the sender's estimate of the amount of time since the response was generated or successfully 977 validated at the origin server. Age values are calculated as specified in <a href="#age.calculations" title="Calculating Age">Section 2.3.2</a>. 978 978 </p> 979 979 <div id="rfc.figure.u.7"></div><pre class="inline"><span id="rfc.iref.g.1"></span><span id="rfc.iref.g.2"></span> <a href="#header.age" class="smpl">Age</a> = "Age" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.age" class="smpl">Age-v</a> … … 992 992 <div id="rfc.iref.h.3"></div> 993 993 <h2 id="rfc.section.3.2"><a href="#rfc.section.3.2">3.2</a> <a id="header.cache-control" href="#header.cache-control">Cache-Control</a></h2> 994 <p id="rfc.section.3.2.p.1">The "Cache-Control" general-header field is used to specify directives that <em class="bcp14">MUST</em> be obeyed by all caches along the request/response chain. The directives specify behavior intended to prevent caches from 995 adversely interfering with the request or response. Cache directives are unidirectional in that the presence of a directive 996 in a request does not imply that the same directive is to be given in the response. 994 <p id="rfc.section.3.2.p.1">The "Cache-Control" general-header field is used to specify directives that <em class="bcp14">MUST</em> be obeyed by all caches along the request/response chain. Such cache directives are unidirectional in that the presence of 995 a directive in a request does not imply that the same directive is to be given in the response. 997 996 </p> 998 997 <div class="note"> … … 1237 1236 <div id="rfc.iref.h.6"></div> 1238 1237 <h2 id="rfc.section.3.5"><a href="#rfc.section.3.5">3.5</a> <a id="header.vary" href="#header.vary">Vary</a></h2> 1239 <p id="rfc.section.3.5.p.1">The "Vary" response-header field's value indicates the set of request-header fields that determines, while the response is 1240 fresh, whether a cache is permitted to use the response to reply to a subsequent request without validation; see <a href="#caching.negotiated.responses" title="Caching Negotiated Responses">Section 2.6</a>. 1241 </p> 1242 <p id="rfc.section.3.5.p.2">In uncacheable or stale responses, the Vary field value advises the user agent about the criteria that were used to select 1238 <p id="rfc.section.3.5.p.1">The "Vary" response-header field conveys the set of request-header fields that were used to select the representation.</p> 1239 <p id="rfc.section.3.5.p.2">Caches use this information, in part, to determine whether a stored response can be used to satisdy a given request; see <a href="#caching.negotiated.responses" title="Caching Negotiated Responses">Section 2.6</a>. determines, while the response is fresh, whether a cache is permitted to use the response to reply to a subsequent request 1240 without validation; see <a href="#caching.negotiated.responses" title="Caching Negotiated Responses">Section 2.6</a>. 1241 </p> 1242 <p id="rfc.section.3.5.p.3">In uncacheable or stale responses, the Vary field value advises the user agent about the criteria that were used to select 1243 1243 the representation. 1244 1244 </p> 1245 1245 <div id="rfc.figure.u.16"></div><pre class="inline"><span id="rfc.iref.g.15"></span><span id="rfc.iref.g.16"></span> <a href="#header.vary" class="smpl">Vary</a> = "Vary" ":" <a href="#core.rules" class="smpl">OWS</a> <a href="#header.vary" class="smpl">Vary-v</a> 1246 1246 <a href="#header.vary" class="smpl">Vary-v</a> = "*" / 1#<a href="#abnf.dependencies" class="smpl">field-name</a> 1247 </pre><p id="rfc.section.3.5.p. 4">The set of header fields named by the Vary field value is known as the selecting request-headers.</p>1248 <p id="rfc.section.3.5.p. 5">Servers <em class="bcp14">SHOULD</em> include a Vary header field with any cacheable response that is subject to server-driven negotiation. Doing so allows a cache1247 </pre><p id="rfc.section.3.5.p.5">The set of header fields named by the Vary field value is known as the selecting request-headers.</p> 1248 <p id="rfc.section.3.5.p.6">Servers <em class="bcp14">SHOULD</em> include a Vary header field with any cacheable response that is subject to server-driven negotiation. Doing so allows a cache 1249 1249 to properly interpret future requests on that resource and informs the user agent about the presence of negotiation on that 1250 1250 resource. A server <em class="bcp14">MAY</em> include a Vary header field with a non-cacheable response that is subject to server-driven negotiation, since this might provide 1251 1251 the user agent with useful information about the dimensions over which the response varies at the time of the response. 1252 1252 </p> 1253 <p id="rfc.section.3.5.p. 6">A Vary field value of "*" signals that unspecified parameters not limited to the request-headers (e.g., the network address1253 <p id="rfc.section.3.5.p.7">A Vary field value of "*" signals that unspecified parameters not limited to the request-headers (e.g., the network address 1254 1254 of the client), play a role in the selection of the response representation; therefore, a cache cannot determine whether this 1255 1255 response is appropriate. The "*" value <em class="bcp14">MUST NOT</em> be generated by a proxy server; it may only be generated by an origin server. 1256 1256 </p> 1257 <p id="rfc.section.3.5.p. 7">The field-names given are not limited to the set of standard request-header fields defined by this specification. Field names1257 <p id="rfc.section.3.5.p.8">The field-names given are not limited to the set of standard request-header fields defined by this specification. Field names 1258 1258 are case-insensitive. 1259 1259 </p>
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