Changeset 786 for draft-ietf-httpbis/latest/p6-cache.html

Timestamp:

Mar 10, 2010, 7:29:39 AM (10 years ago)

Author:

julian.reschke@…

Message:

re-organize field descriptions and pseudo-code for age calculation, preparing for work on #29.

File:

• draft-ietf-httpbis/latest/p6-cache.html (modified) (1 diff)

draft-ietf-httpbis/latest/p6-cache.html

@@ -884 +884 @@
       <p id="rfc.section.2.3.2.p.8">A response's age can be calculated in two entirely independent ways: </p>
       <ol>
-         <li>now minus date_value, if the local clock is reasonably well synchronized to the origin server's clock. If the result is negative,
-            the result is replaced by zero.
+         <li>the "apparent_age": response_time minus date_value, if the local clock is reasonably well synchronized to the origin server's
+            clock. If the result is negative, the result is replaced by zero.
          </li>
          <li>age_value, if all of the caches along the response path implement HTTP/1.1.</li>
       </ol>
       <div id="rfc.figure.u.4"></div> 
-      <p>These are combined as</p>  <pre class="text">  corrected_received_age = max(now - date_value, age_value)
+      <p>These are combined as</p>  <pre class="text">  apparent_age = max(0, response_time - date_value);
+  corrected_received_age = max(apparent_age, age_value);
 </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.
       </p>
-      <div id="rfc.figure.u.5"></div><pre class="text">  corrected_initial_age = corrected_received_age 
-                          + (now - request_time)
+      <div id="rfc.figure.u.5"></div><pre class="text">  response_delay = response_time - request_time;
+  corrected_initial_age = corrected_received_age + response_delay;
 </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
          was last validated by the origin server to the corrected_initial_age.
       </p>
-      <div id="rfc.figure.u.6"></div> 
-      <p>With these definitions, the current_age can be calculated as per:</p>  <pre class="text">  apparent_age = max(0, response_time - date_value);
-  corrected_received_age = max(apparent_age, age_value);
-  response_delay = response_time - request_time;
-  corrected_initial_age = corrected_received_age + response_delay;
-  resident_time = now - response_time;
-  current_age   = corrected_initial_age + resident_time;
+      <div id="rfc.figure.u.6"></div><pre class="text">  resident_time = now - response_time;
+  current_age = corrected_initial_age + resident_time;
 </pre><h3 id="rfc.section.2.3.3"><a href="#rfc.section.2.3.3">2.3.3</a>&nbsp;<a id="serving.stale.responses" href="#serving.stale.responses">Serving Stale Responses</a></h3>
       <p id="rfc.section.2.3.3.p.1">A "stale" response is one that either has explicit expiry information or is allowed to have heuristic expiry calculated, but