Changeset 792


Ignore:
Timestamp:
Mar 17, 2010, 3:11:28 AM (10 years ago)
Author:
julian.reschke@…
Message:

make age calculation a bit less conservative (related to #29)

Location:
draft-ietf-httpbis/latest
Files:
2 edited

Legend:

Unmodified
Added
Removed
  • draft-ietf-httpbis/latest/p6-cache.html

    r786 r792  
    402402      <meta name="dct.creator" content="Reschke, J. F.">
    403403      <meta name="dct.identifier" content="urn:ietf:id:draft-ietf-httpbis-p6-cache-latest">
    404       <meta name="dct.issued" scheme="ISO8601" content="2010-03-10">
     404      <meta name="dct.issued" scheme="ISO8601" content="2010-03-17">
    405405      <meta name="dct.replaces" content="urn:ietf:rfc:2616">
    406406      <meta name="dct.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 &#34;HTTP/1.1&#34; 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.">
     
    428428            </tr>
    429429            <tr>
    430                <td class="left">Expires: September 11, 2010</td>
     430               <td class="left">Expires: September 18, 2010</td>
    431431               <td class="right">J. Mogul</td>
    432432            </tr>
     
    489489            <tr>
    490490               <td class="left"></td>
    491                <td class="right">March 10, 2010</td>
     491               <td class="right">March 17, 2010</td>
    492492            </tr>
    493493         </tbody>
     
    519519      <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>.
    520520      </p>
    521       <p>This Internet-Draft will expire in September 11, 2010.</p>
     521      <p>This Internet-Draft will expire in September 18, 2010.</p>
    522522      <h1><a id="rfc.copyrightnotice" href="#rfc.copyrightnotice">Copyright Notice</a></h1>
    523523      <p>Copyright © 2010 IETF Trust and the persons identified as the document authors. All rights reserved.</p>
     
    887887            clock. If the result is negative, the result is replaced by zero.
    888888         </li>
    889          <li>age_value, if all of the caches along the response path implement HTTP/1.1.</li>
     889         <li>the "corrected_age_value", if all of the caches along the response path implement HTTP/1.1; note this value <em class="bcp14">MUST</em> be interpreted relative to the time the request was initiated, not the time that the response was received.
     890         </li>
    890891      </ol>
    891       <div id="rfc.figure.u.4"></div>
    892       <p>These are combined as</p>  <pre class="text">  apparent_age = max(0, response_time - date_value);
    893   corrected_received_age = max(apparent_age, age_value);
    894 </pre><p id="rfc.section.2.3.2.p.10">When an Age value is received, it <em class="bcp14">MUST</em> be interpreted relative to the time the request was initiated, not the time that the response was received.
    895       </p>
    896       <div id="rfc.figure.u.5"></div><pre class="text">  response_delay = response_time - request_time;
    897   corrected_initial_age = corrected_received_age + response_delay;
    898 </pre><p id="rfc.section.2.3.2.p.12">The current_age of a stored response can then be calculated by adding the amount of time (in seconds) since the stored response
     892      <div id="rfc.figure.u.4"></div> <pre class="text">  apparent_age = max(0, response_time - date_value);
     893
     894  response_delay = response_time - request_time;
     895  corrected_age_value = age_value + response_delay; 
     896</pre> <div id="rfc.figure.u.5"></div>
     897      <p>These are combined as</p>  <pre class="text">  corrected_initial_age = max(apparent_age, corrected_age_value);
     898</pre><p id="rfc.section.2.3.2.p.11">The current_age of a stored response can then be calculated by adding the amount of time (in seconds) since the stored response
    899899         was last validated by the origin server to the corrected_initial_age.
    900900      </p>
     
    17721772      </ul>
    17731773      <h2 id="rfc.section.C.11"><a href="#rfc.section.C.11">C.11</a>&nbsp;<a id="changes.since.09" href="#changes.since.09">Since draft-ietf-httpbis-p6-cache-09</a></h2>
    1774       <p id="rfc.section.C.11.p.1">No significant changes.</p>
     1774      <p id="rfc.section.C.11.p.1">Closed issues: </p>
     1775      <ul>
     1776         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/29">http://tools.ietf.org/wg/httpbis/trac/ticket/29</a>&gt;: "Age calculation"
     1777         </li>
     1778      </ul>
    17751779      <h1 id="rfc.index"><a href="#rfc.index">Index</a></h1>
    17761780      <p class="noprint"><a href="#rfc.index.A">A</a> <a href="#rfc.index.C">C</a> <a href="#rfc.index.E">E</a> <a href="#rfc.index.F">F</a> <a href="#rfc.index.G">G</a> <a href="#rfc.index.H">H</a> <a href="#rfc.index.M">M</a> <a href="#rfc.index.N">N</a> <a href="#rfc.index.O">O</a> <a href="#rfc.index.P">P</a> <a href="#rfc.index.R">R</a> <a href="#rfc.index.S">S</a> <a href="#rfc.index.V">V</a> <a href="#rfc.index.W">W</a>
  • draft-ietf-httpbis/latest/p6-cache.xml

    r786 r792  
    687687    <t>the "apparent_age": response_time minus date_value, if the local clock is reasonably well synchronized to the
    688688      origin server's clock. If the result is negative, the result is replaced by zero.</t>
    689     <t>age_value, if all of the caches along the response path implement HTTP/1.1.</t>
    690   </list>
    691 </t>
     689    <t>the "corrected_age_value", if all of the caches along the response path implement HTTP/1.1;
     690      note this value &MUST; be interpreted relative to the time the
     691      request was initiated, not the time that the response was received.</t>
     692  </list>
     693</t>
     694<figure>
     695<artwork type="code">
     696  apparent_age = max(0, response_time - date_value);
     697
     698  response_delay = response_time - request_time;
     699  corrected_age_value = age_value + response_delay; 
     700</artwork>
     701</figure>
    692702<figure>
    693703<preamble>These are combined as</preamble>
    694704<artwork type="code">
    695   apparent_age = max(0, response_time - date_value);
    696   corrected_received_age = max(apparent_age, age_value);
    697 </artwork></figure>
    698 <t>
    699   When an Age value is received, it &MUST; be interpreted relative to the time the
    700   request was initiated, not the time that the response was received.
    701 </t>
    702 <figure><artwork type="code">
    703   response_delay = response_time - request_time;
    704   corrected_initial_age = corrected_received_age + response_delay;
     705  corrected_initial_age = max(apparent_age, corrected_age_value);
    705706</artwork></figure>
    706707<t>
     
    23302331<section title="Since draft-ietf-httpbis-p6-cache-09" anchor="changes.since.09">
    23312332<t>
    2332   No significant changes.
     2333  Closed issues:
     2334  <list style="symbols">
     2335    <t>
     2336      <eref target="http://tools.ietf.org/wg/httpbis/trac/ticket/29" />:
     2337      "Age calculation"
     2338    </t>
     2339  </list>
    23332340</t>
    23342341</section>
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