Changeset 2088 for draft-ietf-httpbis/latest/p6-cache.html
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- 05/01/13 11:42:34 (10 years ago)
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draft-ietf-httpbis/latest/p6-cache.html
r2082 r2088 452 452 } 453 453 @bottom-center { 454 content: "Expires July 8, 2013";454 content: "Expires July 9, 2013"; 455 455 } 456 456 @bottom-right { … … 498 498 <meta name="dct.creator" content="Reschke, J. F."> 499 499 <meta name="dct.identifier" content="urn:ietf:id:draft-ietf-httpbis-p6-cache-latest"> 500 <meta name="dct.issued" scheme="ISO8601" content="2013-01-0 4">500 <meta name="dct.issued" scheme="ISO8601" content="2013-01-05"> 501 501 <meta name="dct.replaces" content="urn:ietf:rfc:2616"> 502 502 <meta name="dct.abstract" content="The Hypertext Transfer Protocol (HTTP) is an application-level protocol for distributed, collaborative, hypertext information systems. This document defines requirements on HTTP caches and the associated header fields that control cache behavior or indicate cacheable response messages."> … … 524 524 </tr> 525 525 <tr> 526 <td class="left">Expires: July 8, 2013</td>526 <td class="left">Expires: July 9, 2013</td> 527 527 <td class="right">J. Reschke, Editor</td> 528 528 </tr> … … 533 533 <tr> 534 534 <td class="left"></td> 535 <td class="right">January 4, 2013</td>535 <td class="right">January 5, 2013</td> 536 536 </tr> 537 537 </tbody> … … 559 559 in progress”. 560 560 </p> 561 <p>This Internet-Draft will expire on July 8, 2013.</p>561 <p>This Internet-Draft will expire on July 9, 2013.</p> 562 562 <h1><a id="rfc.copyrightnotice" href="#rfc.copyrightnotice">Copyright Notice</a></h1> 563 563 <p>Copyright © 2013 IETF Trust and the persons identified as the document authors. All rights reserved.</p> … … 795 795 </p> 796 796 <p id="rfc.section.2.p.2">Each <dfn>cache entry</dfn> consists of a cache key and one or more HTTP responses corresponding to prior requests that used the same key. The most common 797 form of cache entry is a successful result of a retrieval request: i.e., a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response containing a representation of the resource identified by the request target. However, it is also possible to cache 798 negative results (e.g., <a href="p2-semantics.html#status.404" class="smpl">404 (Not 799 Found)</a>, incomplete results (e.g., <a href="p5-range.html#status.206" class="smpl">206 (Partial 800 Content)</a>), and responses to methods other than GET if the method's definition allows such caching and defines something suitable for 797 form of cache entry is a successful result of a retrieval request: i.e., a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response to a GET request, which contains a representation of the resource identified by the request target (<a href="p2-semantics.html#GET" title="GET">Section 4.3.1</a> of <a href="#Part2" id="rfc.xref.Part2.2"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>). However, it is also possible to cache negative results (e.g., <a href="p2-semantics.html#status.404" class="smpl">404 (Not Found)</a>), incomplete results (e.g., <a href="p5-range.html#status.206" class="smpl">206 (Partial Content)</a>), and responses to methods other than GET if the method's definition allows such caching and defines something suitable for 801 798 use as a cache key. 802 799 </p> … … 886 883 <p id="rfc.section.4.p.3">When a stored response is used to satisfy a request without validation, a cache <em class="bcp14">MUST</em> send a single <a href="#header.age" class="smpl">Age</a> header field (<a href="#header.age" id="rfc.xref.header.age.1" title="Age">Section 7.1</a>) in the response with a value equal to the stored response's current_age; see <a href="#age.calculations" title="Calculating Age">Section 4.1.3</a>. 887 884 </p> 888 <p id="rfc.section.4.p.4">A cache <em class="bcp14">MUST</em> write through requests with methods that are unsafe (<a href="p2-semantics.html#safe.methods" title="Safe Methods">Section 4.2.1</a> of <a href="#Part2" id="rfc.xref.Part2. 2"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) to the origin server; i.e., a cache is not allowed to generate a reply to such a request before having forwarded the request885 <p id="rfc.section.4.p.4">A cache <em class="bcp14">MUST</em> write through requests with methods that are unsafe (<a href="p2-semantics.html#safe.methods" title="Safe Methods">Section 4.2.1</a> of <a href="#Part2" id="rfc.xref.Part2.3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) to the origin server; i.e., a cache is not allowed to generate a reply to such a request before having forwarded the request 889 886 and having received a corresponding response. 890 887 </p> … … 940 937 <h3 id="rfc.section.4.1.2"><a href="#rfc.section.4.1.2">4.1.2</a> <a id="heuristic.freshness" href="#heuristic.freshness">Calculating Heuristic Freshness</a></h3> 941 938 <p id="rfc.section.4.1.2.p.1">If no explicit expiration time is present in a stored response that has a status code whose definition allows heuristic freshness 942 to be used (including the following in <a href="p2-semantics.html#status.codes" title="Response Status Codes">Section 6</a> of <a href="#Part2" id="rfc.xref.Part2. 3"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>: <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a>, <a href="p2-semantics.html#status.203" class="smpl">203 (Non-Authoritative Information)</a>, <a href="p5-range.html#status.206" class="smpl">206 (Partial939 to be used (including the following in <a href="p2-semantics.html#status.codes" title="Response Status Codes">Section 6</a> of <a href="#Part2" id="rfc.xref.Part2.4"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>: <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a>, <a href="p2-semantics.html#status.203" class="smpl">203 (Non-Authoritative Information)</a>, <a href="p5-range.html#status.206" class="smpl">206 (Partial 943 940 Content)</a>, <a href="p2-semantics.html#status.300" class="smpl">300 (Multiple Choices)</a>, <a href="p2-semantics.html#status.301" class="smpl">301 (Moved 944 941 Permanently)</a> and <a href="p2-semantics.html#status.410" class="smpl">410 (Gone)</a>), a cache <em class="bcp14">MAY</em> calculate a heuristic expiration time. A cache <em class="bcp14">MUST NOT</em> use heuristics to determine freshness for responses with status codes that do not explicitly allow it. … … 972 969 </p> 973 970 <ul class="empty"> 974 <li>The term "date_value" denotes the value of the Date header field, in a form appropriate for arithmetic operations. See <a href="p2-semantics.html#header.date" title="Date">Section 7.1.1.2</a> of <a href="#Part2" id="rfc.xref.Part2. 4"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a> for the definition of the Date header field, and for requirements regarding responses without it.971 <li>The term "date_value" denotes the value of the Date header field, in a form appropriate for arithmetic operations. See <a href="p2-semantics.html#header.date" title="Date">Section 7.1.1.2</a> of <a href="#Part2" id="rfc.xref.Part2.5"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a> for the definition of the Date header field, and for requirements regarding responses without it. 975 972 </li> 976 973 </ul> … … 1092 1089 </ul> 1093 1090 <h2 id="rfc.section.4.3"><a href="#rfc.section.4.3">4.3</a> <a id="caching.negotiated.responses" href="#caching.negotiated.responses">Using Negotiated Responses</a></h2> 1094 <p id="rfc.section.4.3.p.1">When a cache receives a request that can be satisfied by a stored response that has a <a href="p2-semantics.html#header.vary" class="smpl">Vary</a> header field (<a href="p2-semantics.html#header.vary" title="Vary">Section 7.2.1</a> of <a href="#Part2" id="rfc.xref.Part2. 5"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>), it <em class="bcp14">MUST NOT</em> use that response unless all of the selecting header fields nominated by the Vary header field match in both the original1091 <p id="rfc.section.4.3.p.1">When a cache receives a request that can be satisfied by a stored response that has a <a href="p2-semantics.html#header.vary" class="smpl">Vary</a> header field (<a href="p2-semantics.html#header.vary" title="Vary">Section 7.2.1</a> of <a href="#Part2" id="rfc.xref.Part2.6"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>), it <em class="bcp14">MUST NOT</em> use that response unless all of the selecting header fields nominated by the Vary header field match in both the original 1095 1092 request (i.e., that associated with the stored response), and the presented request. 1096 1093 </p> … … 1151 1148 </ul> 1152 1149 <h1 id="rfc.section.6"><a href="#rfc.section.6">6.</a> <a id="invalidation.after.updates.or.deletions" href="#invalidation.after.updates.or.deletions">Request Methods that Invalidate</a></h1> 1153 <p id="rfc.section.6.p.1">Because unsafe request methods (<a href="p2-semantics.html#safe.methods" title="Safe Methods">Section 4.2.1</a> of <a href="#Part2" id="rfc.xref.Part2. 6"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) such as PUT, POST or DELETE have the potential for changing state on the origin server, intervening caches can use them1150 <p id="rfc.section.6.p.1">Because unsafe request methods (<a href="p2-semantics.html#safe.methods" title="Safe Methods">Section 4.2.1</a> of <a href="#Part2" id="rfc.xref.Part2.7"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>) such as PUT, POST or DELETE have the potential for changing state on the origin server, intervening caches can use them 1154 1151 to keep their contents up-to-date. 1155 1152 </p> … … 1419 1416 that time. 1420 1417 </p> 1421 <p id="rfc.section.7.3.p.3">The Expires value is an HTTP-date timestamp, as defined in <a href="p2-semantics.html#http.date" title="Date/Time Formats">Section 7.1.1.1</a> of <a href="#Part2" id="rfc.xref.Part2. 7"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>.1418 <p id="rfc.section.7.3.p.3">The Expires value is an HTTP-date timestamp, as defined in <a href="p2-semantics.html#http.date" title="Date/Time Formats">Section 7.1.1.1</a> of <a href="#Part2" id="rfc.xref.Part2.8"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>. 1422 1419 </p> 1423 1420 <div id="rfc.figure.u.9"></div><pre class="inline"><span id="rfc.iref.g.5"></span> <a href="#header.expires" class="smpl">Expires</a> = <a href="#imported.abnf" class="smpl">HTTP-date</a> … … 1776 1773 <h1 id="rfc.section.10"><a href="#rfc.section.10">10.</a> <a id="security.considerations" href="#security.considerations">Security Considerations</a></h1> 1777 1774 <p id="rfc.section.10.p.1">This section is meant to inform developers, information providers, and users of known security concerns specific to HTTP/1.1 1778 caching. More general security considerations are addressed in HTTP messaging <a href="#Part1" id="rfc.xref.Part1.11"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a> and semantics <a href="#Part2" id="rfc.xref.Part2. 8"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>.1775 caching. More general security considerations are addressed in HTTP messaging <a href="#Part1" id="rfc.xref.Part1.11"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a> and semantics <a href="#Part2" id="rfc.xref.Part2.9"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>. 1779 1776 </p> 1780 1777 <p id="rfc.section.10.p.2">Caches expose additional potential vulnerabilities, since the contents of the cache represent an attractive target for malicious … … 1952 1949 <a href="#imported.abnf" class="smpl">uri-host</a> = <uri-host, defined in <a href="#Part1" id="rfc.xref.Part1.20"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Message Syntax and Routing">[Part1]</cite></a>, <a href="p1-messaging.html#uri" title="Uniform Resource Identifiers">Section 2.7</a>> 1953 1950 </pre><p id="rfc.section.B.p.4">The rules below are defined in other parts:</p> 1954 <div id="rfc.figure.u.15"></div><pre class="inline"> <a href="#imported.abnf" class="smpl">HTTP-date</a> = <HTTP-date, defined in <a href="#Part2" id="rfc.xref.Part2. 9"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>, <a href="p2-semantics.html#http.date" title="Date/Time Formats">Section 7.1.1.1</a>>1951 <div id="rfc.figure.u.15"></div><pre class="inline"> <a href="#imported.abnf" class="smpl">HTTP-date</a> = <HTTP-date, defined in <a href="#Part2" id="rfc.xref.Part2.10"><cite title="Hypertext Transfer Protocol (HTTP/1.1): Semantics and Content">[Part2]</cite></a>, <a href="p2-semantics.html#http.date" title="Date/Time Formats">Section 7.1.1.1</a>> 1955 1952 </pre><h1 id="rfc.section.C"><a href="#rfc.section.C">C.</a> <a id="collected.abnf" href="#collected.abnf">Collected ABNF</a></h1> 1956 1953 <div id="rfc.figure.u.16"></div> <pre class="inline"><a href="#header.age" class="smpl">Age</a> = delta-seconds … … 2138 2135 </ul> 2139 2136 </li> 2140 <li><em>Part2</em> <a href="#rfc.xref.Part2.1">2</a>, <a href="#rfc.xref.Part2.2">4</a>, <a href="#rfc.xref.Part2.3">4.1.2</a>, <a href="#rfc.xref.Part2.4">4.1.3</a>, <a href="#rfc.xref.Part2.5">4.3</a>, <a href="#rfc.xref.Part2.6">6</a>, <a href="#rfc.xref.Part2.7">7.3</a>, <a href="#rfc.xref.Part2.8">10</a>, <a href="#Part2"><b>12.1</b></a>, <a href="#rfc.xref.Part2.9">B</a><ul> 2141 <li><em>Section 4.2.1</em> <a href="#rfc.xref.Part2.2">4</a>, <a href="#rfc.xref.Part2.6">6</a></li> 2142 <li><em>Section 6</em> <a href="#rfc.xref.Part2.3">4.1.2</a></li> 2143 <li><em>Section 7.1.1.1</em> <a href="#rfc.xref.Part2.7">7.3</a>, <a href="#rfc.xref.Part2.9">B</a></li> 2144 <li><em>Section 7.1.1.2</em> <a href="#rfc.xref.Part2.4">4.1.3</a></li> 2145 <li><em>Section 7.2.1</em> <a href="#rfc.xref.Part2.5">4.3</a></li> 2137 <li><em>Part2</em> <a href="#rfc.xref.Part2.1">2</a>, <a href="#rfc.xref.Part2.2">2</a>, <a href="#rfc.xref.Part2.3">4</a>, <a href="#rfc.xref.Part2.4">4.1.2</a>, <a href="#rfc.xref.Part2.5">4.1.3</a>, <a href="#rfc.xref.Part2.6">4.3</a>, <a href="#rfc.xref.Part2.7">6</a>, <a href="#rfc.xref.Part2.8">7.3</a>, <a href="#rfc.xref.Part2.9">10</a>, <a href="#Part2"><b>12.1</b></a>, <a href="#rfc.xref.Part2.10">B</a><ul> 2138 <li><em>Section 4.2.1</em> <a href="#rfc.xref.Part2.3">4</a>, <a href="#rfc.xref.Part2.7">6</a></li> 2139 <li><em>Section 4.3.1</em> <a href="#rfc.xref.Part2.2">2</a></li> 2140 <li><em>Section 6</em> <a href="#rfc.xref.Part2.4">4.1.2</a></li> 2141 <li><em>Section 7.1.1.1</em> <a href="#rfc.xref.Part2.8">7.3</a>, <a href="#rfc.xref.Part2.10">B</a></li> 2142 <li><em>Section 7.1.1.2</em> <a href="#rfc.xref.Part2.5">4.1.3</a></li> 2143 <li><em>Section 7.2.1</em> <a href="#rfc.xref.Part2.6">4.3</a></li> 2146 2144 </ul> 2147 2145 </li>
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