Changeset 1738 for draft-ietf-httpbis/latest/p4-conditional.html
- Timestamp:
- 08/07/12 13:29:53 (10 years ago)
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draft-ietf-httpbis/latest/p4-conditional.html
r1737 r1738 770 770 <ul> 771 771 <li>The validator is about to be used by a client in an If-Modified-Since, If-Unmodified-Since header field, because the client 772 has a cache entry, or If-Rangefor the associated representation, and772 has a cache entry, or <a href="p5-range.html#header.if-range" class="smpl">If-Range</a> for the associated representation, and 773 773 </li> 774 774 <li>That cache entry includes a Date value, which gives the time when the origin server sent the original response, and</li> … … 954 954 </ul> 955 955 <p id="rfc.section.2.4.p.5">An HTTP/1.1 origin server, upon receiving a conditional request that includes both a Last-Modified date (e.g., in an If-Modified-Since 956 or If-Unmodified-Since header field) and one or more entity-tags (e.g., in an If-Match, If-None-Match, or If-Range header 957 field) as cache validators, <em class="bcp14">MUST NOT</em> return a response status code of <a href="#status.304" class="smpl">304 (Not Modified)</a> unless doing so is consistent with all of the conditional header fields in the request. 956 or If-Unmodified-Since header field) and one or more entity-tags (e.g., in an If-Match, If-None-Match, or <a href="p5-range.html#header.if-range" class="smpl">If-Range</a> header field) as cache validators, <em class="bcp14">MUST NOT</em> return a response status code of <a href="#status.304" class="smpl">304 (Not Modified)</a> unless doing so is consistent with all of the conditional header fields in the request. 958 957 </p> 959 958 <p id="rfc.section.2.4.p.6">An HTTP/1.1 caching proxy, upon receiving a conditional request that includes both a Last-Modified date and one or more entity-tags … … 1042 1041 </pre><p id="rfc.section.3.3.p.3">An example of the field is:</p> 1043 1042 <div id="rfc.figure.u.14"></div><pre class="text"> If-Modified-Since: Sat, 29 Oct 1994 19:43:31 GMT 1044 </pre><p id="rfc.section.3.3.p.5">A GET method with an If-Modified-Since header field and no Range header field requests that the selected representation be 1045 transferred only if it has been modified since the date given by the If-Modified-Since header field. The algorithm for determining 1046 this includes the following cases: 1043 </pre><p id="rfc.section.3.3.p.5">A GET method with an If-Modified-Since header field and no <a href="p5-range.html#range.retrieval.requests" class="smpl">Range</a> header field requests that the selected representation be transferred only if it has been modified since the date given by 1044 the If-Modified-Since header field. The algorithm for determining this includes the following cases: 1047 1045 </p> 1048 1046 <ol> … … 1058 1056 <p id="rfc.section.3.3.p.6">The purpose of this feature is to allow efficient updates of cached information with a minimum amount of transaction overhead. </p> 1059 1057 <ul class="empty"> 1060 <li> <b>Note:</b> The Rangeheader field modifies the meaning of If-Modified-Since; see <a href="p5-range.html#header.range" title="Range">Section 5.4</a> of <a href="#Part5" id="rfc.xref.Part5.1"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a> for full details.1058 <li> <b>Note:</b> The <a href="p5-range.html#range.retrieval.requests" class="smpl">Range</a> header field modifies the meaning of If-Modified-Since; see <a href="p5-range.html#header.range" title="Range">Section 5.4</a> of <a href="#Part5" id="rfc.xref.Part5.1"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a> for full details. 1061 1059 </li> 1062 1060 <li> <b>Note:</b> If-Modified-Since times are interpreted by the server, whose clock might not be synchronized with the client. … … 1095 1093 </p> 1096 1094 <h2 id="rfc.section.3.5"><a href="#rfc.section.3.5">3.5</a> <a id="header.if-range" href="#header.if-range">If-Range</a></h2> 1097 <p id="rfc.section.3.5.p.1">The If-Rangeheader field provides a special conditional request mechanism that is similar to If-Match and If-Unmodified-Since1095 <p id="rfc.section.3.5.p.1">The "If-Range" header field provides a special conditional request mechanism that is similar to If-Match and If-Unmodified-Since 1098 1096 but specific to HTTP range requests. If-Range is defined in <a href="p5-range.html#header.if-range" title="If-Range">Section 5.3</a> of <a href="#Part5" id="rfc.xref.Part5.2"><cite title="HTTP/1.1, part 5: Range Requests and Partial Responses">[Part5]</cite></a>. 1099 1097 </p>
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