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Timestamp:
Jul 8, 2012, 7:50:41 AM (7 years ago)
Author:
julian.reschke@…
Message:

Work-in-progress: hyperlink header field definitions(P4)

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1 edited

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  • draft-ietf-httpbis/latest/p5-range.html

    r1738 r1739  
    742742         </li>
    743743         <li>Date</li>
    744          <li>Cache-Control, ETag, <a href="p6-cache.html#header.expires" class="smpl">Expires</a>, Content-Location and/or Vary, if the header field would have been sent in a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response to the same request
     744         <li> <a href="p6-cache.html#header.cache-control" class="smpl">Cache-Control</a>, <a href="p4-conditional.html#header.etag" class="smpl">ETag</a>, <a href="p6-cache.html#header.expires" class="smpl">Expires</a>, Content-Location and/or <a href="p6-cache.html#header.vary" class="smpl">Vary</a>, if the header field would have been sent in a <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> response to the same request
    745745         </li>
    746746      </ul>
     
    794794         one or more Range specifications. After several such transfers, a client might have received several ranges of the same representation.
    795795         These ranges can only be safely combined if they all have in common the same strong validator, where "strong validator" is
    796          defined to be either an entity-tag that is not marked as weak (<a href="p4-conditional.html#header.etag" title="ETag">Section 2.3</a> of <a href="#Part4" id="rfc.xref.Part4.2"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>) or, if no entity-tag is provided, a Last-Modified value that is strong in the sense defined by <a href="p4-conditional.html#lastmod.comparison" title="Comparison">Section 2.2.2</a> of <a href="#Part4" id="rfc.xref.Part4.3"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>.
     796         defined to be either an entity-tag that is not marked as weak (<a href="p4-conditional.html#header.etag" title="ETag">Section 2.3</a> of <a href="#Part4" id="rfc.xref.Part4.2"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>) or, if no entity-tag is provided, a <a href="p4-conditional.html#header.last-modified" class="smpl">Last-Modified</a> value that is strong in the sense defined by <a href="p4-conditional.html#lastmod.comparison" title="Comparison">Section 2.2.2</a> of <a href="#Part4" id="rfc.xref.Part4.3"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>.
    797797      </p>
    798798      <p id="rfc.section.4.2.p.2">When a client receives an incomplete <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a> or <a href="#status.206" class="smpl">206 (Partial Content)</a> response and already has one or more stored responses for the same method and effective request URI, all of the stored responses
     
    888888      <h2 id="rfc.section.5.3"><a href="#rfc.section.5.3">5.3</a>&nbsp;<a id="header.if-range" href="#header.if-range">If-Range</a></h2>
    889889      <p id="rfc.section.5.3.p.1">If a client has a partial copy of a representation and wishes to have an up-to-date copy of the entire representation, it
    890          could use the <a href="#range.retrieval.requests" class="smpl">Range</a> header field with a conditional GET (using either or both of If-Unmodified-Since and If-Match.) However, if the condition
    891          fails because the representation has been modified, the client would then have to make a second request to obtain the entire
    892          current representation.
     890         could use the <a href="#range.retrieval.requests" class="smpl">Range</a> header field with a conditional GET (using either or both of <a href="p4-conditional.html#header.if-unmodified-since" class="smpl">If-Unmodified-Since</a> and <a href="p4-conditional.html#header.if-match" class="smpl">If-Match</a>.) However, if the condition fails because the representation has been modified, the client would then have to make a second
     891         request to obtain the entire current representation.
    893892      </p>
    894893      <p id="rfc.section.5.3.p.2">The "If-Range" header field allows a client to "short-circuit" the second request. Informally, its meaning is "if the representation
     
    896895      </p>
    897896      <div id="rfc.figure.u.14"></div><pre class="inline"><span id="rfc.iref.g.10"></span>  <a href="#header.if-range" class="smpl">If-Range</a> = <a href="#abnf.dependencies" class="smpl">entity-tag</a> / <a href="#core.rules" class="smpl">HTTP-date</a>
    898 </pre><p id="rfc.section.5.3.p.4">Clients <em class="bcp14">MUST NOT</em> use an entity-tag marked as weak in an If-Range field value and <em class="bcp14">MUST NOT</em> use a Last-Modified date in an If-Range field value unless it has no entity-tag for the representation and the Last-Modified
    899          date it does have for the representation is strong in the sense defined by <a href="p4-conditional.html#lastmod.comparison" title="Comparison">Section 2.2.2</a> of <a href="#Part4" id="rfc.xref.Part4.4"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>.
     897</pre><p id="rfc.section.5.3.p.4">Clients <em class="bcp14">MUST NOT</em> use an entity-tag marked as weak in an If-Range field value and <em class="bcp14">MUST NOT</em> use a <a href="p4-conditional.html#header.last-modified" class="smpl">Last-Modified</a> date in an If-Range field value unless it has no entity-tag for the representation and the Last-Modified date it does have
     898         for the representation is strong in the sense defined by <a href="p4-conditional.html#lastmod.comparison" title="Comparison">Section 2.2.2</a> of <a href="#Part4" id="rfc.xref.Part4.4"><cite title="HTTP/1.1, part 4: Conditional Requests">[Part4]</cite></a>.
    900899      </p>
    901900      <p id="rfc.section.5.3.p.5">A server that evaluates a conditional range request that is applicable to one of its representations <em class="bcp14">MUST</em> evaluate the condition as false if the entity-tag used as a validator is marked as weak or, when an HTTP-date is used as the
     
    983982            In other words, the response carries a status code of <a href="#status.206" class="smpl">206 (Partial Content)</a> instead of <a href="p2-semantics.html#status.200" class="smpl">200 (OK)</a>.
    984983         </li>
    985          <li>The presence of a Range header field in a conditional GET (a request using one or both of If-Modified-Since and If-None-Match,
    986             or one or both of If-Unmodified-Since and If-Match) modifies what is returned if the GET is otherwise successful and the condition
    987             is true. It does not affect the <a href="p4-conditional.html#status.304" class="smpl">304 (Not Modified)</a> response returned if the conditional is false.
     984         <li>The presence of a Range header field in a conditional GET (a request using one or both of <a href="p4-conditional.html#header.if-modified-since" class="smpl">If-Modified-Since</a> and <a href="p4-conditional.html#header.if-none-match" class="smpl">If-None-Match</a>, or one or both of <a href="p4-conditional.html#header.if-unmodified-since" class="smpl">If-Unmodified-Since</a> and <a href="p4-conditional.html#header.if-match" class="smpl">If-Match</a>) modifies what is returned if the GET is otherwise successful and the condition is true. It does not affect the <a href="p4-conditional.html#status.304" class="smpl">304 (Not Modified)</a> response returned if the conditional is false.
    988985         </li>
    989986      </ul>
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