Changeset 1323 for draft-ietf-httpbis/latest/p6-cache.html

Timestamp:

01/07/11 16:56:52 (11 years ago)

Author:

julian.reschke@…

Message:

add guidance on minimum sizes of protocol elements (see #282)

File:

• draft-ietf-httpbis/latest/p6-cache.html (modified) (10 diffs)

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

@@ -550 +550 @@
                   </ul>
                </li>
+               <li>1.5&nbsp;&nbsp;&nbsp;<a href="#delta-seconds">Delta Seconds</a></li>
             </ul>
          </li>
@@ -740 +741 @@
   <a href="#abnf.dependencies" class="smpl">pseudonym</a>     = &lt;pseudonym, defined in <a href="#Part1" id="rfc.xref.Part1.9"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#header.via" title="Via">Section 9.9</a>&gt; 
   <a href="#abnf.dependencies" class="smpl">uri-host</a>      = &lt;uri-host, defined in <a href="#Part1" id="rfc.xref.Part1.10"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>, <a href="p1-messaging.html#uri" title="Uniform Resource Identifiers">Section 2.7</a>&gt;
-</pre><h1 id="rfc.section.2"><a href="#rfc.section.2">2.</a>&nbsp;<a id="caching.overview" href="#caching.overview">Cache Operation</a></h1>
+</pre><h2 id="rfc.section.1.5"><a href="#rfc.section.1.5">1.5</a>&nbsp;<a id="delta-seconds" href="#delta-seconds">Delta Seconds</a></h2>
+      <p id="rfc.section.1.5.p.1">The delta-seconds rule specifies a non-negative integer, representing time in seconds.</p>
+      <div id="rfc.figure.u.3"></div><pre class="inline"><span id="rfc.iref.g.1"></span>  <a href="#delta-seconds" class="smpl">delta-seconds</a>  = 1*<a href="#notation" class="smpl">DIGIT</a>
+</pre><p id="rfc.section.1.5.p.3">If an implementation receives a delta-seconds value larger than the largest positive integer it can represent, or if any of
+         its subsequent calculations overflows, it <em class="bcp14">MUST</em> consider the value to be 2147483648 (2<sup>31</sup>). Recipients parsing a delta-seconds value <em class="bcp14">SHOULD</em> use an arithmetic type of at least 31 bits of range, and senders <em class="bcp14">MUST NOT</em> send delta-seconds with a value greater than 2147483648.
+      </p>
+      <h1 id="rfc.section.2"><a href="#rfc.section.2">2.</a>&nbsp;<a id="caching.overview" href="#caching.overview">Cache Operation</a></h1>
       <h2 id="rfc.section.2.1"><a href="#rfc.section.2.1">2.1</a>&nbsp;<a id="response.cacheability" href="#response.cacheability">Response Cacheability</a></h2>
       <p id="rfc.section.2.1.p.1">A cache <em class="bcp14">MUST NOT</em> store a response to any request, unless: 
@@ -834 +841 @@
          algorithms, but does impose worst-case constraints on their results.
       </p>
-      <div id="rfc.figure.u.3"></div> 
+      <div id="rfc.figure.u.4"></div> 
       <p>The calculation to determine if a response is fresh is:</p>  <pre class="text">   response_is_fresh = (freshness_lifetime &gt; current_age)
 </pre> <p id="rfc.section.2.3.p.6">The freshness_lifetime is defined in <a href="#calculating.freshness.lifetime" title="Calculating Freshness Lifetime">Section&nbsp;2.3.1</a>; the current_age is defined in <a href="#age.calculations" title="Calculating Age">Section&nbsp;2.3.2</a>.
@@ -918 +925 @@
          </li>
       </ol>
-      <div id="rfc.figure.u.4"></div> <pre class="text">  apparent_age = max(0, response_time - date_value);
+      <div id="rfc.figure.u.5"></div> <pre class="text">  apparent_age = max(0, response_time - date_value);
 
   response_delay = response_time - request_time;
   corrected_age_value = age_value + response_delay;  
-</pre> <div id="rfc.figure.u.5"></div> 
+</pre> <div id="rfc.figure.u.6"></div> 
       <p>These are combined as</p>  <pre class="text">  corrected_initial_age = max(apparent_age, corrected_age_value);
 </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
          was last validated by the origin server to the corrected_initial_age.
       </p>
-      <div id="rfc.figure.u.6"></div><pre class="text">  resident_time = now - response_time;
+      <div id="rfc.figure.u.7"></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>
@@ -1048 +1055 @@
          validated at the origin server. Age values are calculated as specified in <a href="#age.calculations" title="Calculating Age">Section&nbsp;2.3.2</a>.
       </p>
-      <div id="rfc.figure.u.7"></div><pre class="inline"><span id="rfc.iref.g.1"></span>  <a href="#header.age" class="smpl">Age</a> = <a href="#rule.delta-seconds" class="smpl">delta-seconds</a>
-</pre><div id="rule.delta-seconds">
-         <p id="rfc.section.3.1.p.3">  Age field-values are non-negative integers, representing time in seconds.</p>
-      </div>
-      <div id="rfc.figure.u.8"></div><pre class="inline"><span id="rfc.iref.g.2"></span>  <a href="#rule.delta-seconds" class="smpl">delta-seconds</a>  = 1*<a href="#notation" class="smpl">DIGIT</a>
-</pre><p id="rfc.section.3.1.p.5">If a cache receives a value larger than the largest positive integer it can represent, or if any of its age calculations overflows,
-         it <em class="bcp14">MUST</em> transmit an Age header field with a field-value of 2147483648 (2<sup>31</sup>). Recipients parsing the Age header field-value <em class="bcp14">SHOULD</em> use an arithmetic type of at least 31 bits of range.
-      </p>
-      <p id="rfc.section.3.1.p.6">The presence of an Age header field in a response implies that a response is not first-hand. However, the converse is not
+      <div id="rfc.figure.u.8"></div><pre class="inline"><span id="rfc.iref.g.2"></span>  <a href="#header.age" class="smpl">Age</a> = <a href="#delta-seconds" class="smpl">delta-seconds</a>
+</pre><p id="rfc.section.3.1.p.3">Age field-values are non-negative integers, representing time in seconds (see <a href="#delta-seconds" title="Delta Seconds">Section&nbsp;1.5</a>).
+      </p>
+      <p id="rfc.section.3.1.p.4">The presence of an Age header field in a response implies that a response is not first-hand. However, the converse is not
          true, since HTTP/1.0 caches might not implement the Age header field.
       </p>
@@ -1086 +1088 @@
        "no-cache"
      / "no-store"
-     / "max-age" "=" <a href="#rule.delta-seconds" class="smpl">delta-seconds</a>
-     / "max-stale" [ "=" <a href="#rule.delta-seconds" class="smpl">delta-seconds</a> ]
-     / "min-fresh" "=" <a href="#rule.delta-seconds" class="smpl">delta-seconds</a>
+     / "max-age" "=" <a href="#delta-seconds" class="smpl">delta-seconds</a>
+     / "max-stale" [ "=" <a href="#delta-seconds" class="smpl">delta-seconds</a> ]
+     / "min-fresh" "=" <a href="#delta-seconds" class="smpl">delta-seconds</a>
      / "no-transform"
      / "only-if-cached"
@@ -1158 +1160 @@
      / "must-revalidate"
      / "proxy-revalidate"
-     / "max-age" "=" <a href="#rule.delta-seconds" class="smpl">delta-seconds</a>
-     / "s-maxage" "=" <a href="#rule.delta-seconds" class="smpl">delta-seconds</a>
+     / "max-age" "=" <a href="#delta-seconds" class="smpl">delta-seconds</a>
+     / "s-maxage" "=" <a href="#delta-seconds" class="smpl">delta-seconds</a>
      / <a href="#header.cache-control" class="smpl">cache-extension</a>
 </pre><p id="rfc.section.3.2.2.p.2"> <dfn>public</dfn>  <span id="rfc.iref.c.12"></span>  <span id="rfc.iref.p.2"></span>  
@@ -1755 +1757 @@
  ) / ( "s-maxage=" delta-seconds ) / cache-extension
 
-<a href="#rule.delta-seconds" class="smpl">delta-seconds</a> = 1*DIGIT
+<a href="#delta-seconds" class="smpl">delta-seconds</a> = 1*DIGIT
 
 <a href="#header.pragma" class="smpl">extension-pragma</a> = token [ "=" ( token / quoted-string ) ]
@@ -1967 +1969 @@
          </li>
          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/235">http://tools.ietf.org/wg/httpbis/trac/ticket/235</a>&gt;: "Cache Invalidation only happens upon successful responses"
+         </li>
+         <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/282">http://tools.ietf.org/wg/httpbis/trac/ticket/282</a>&gt;: "Recommend minimum sizes for protocol elements"
          </li>
          <li> &lt;<a href="http://tools.ietf.org/wg/httpbis/trac/ticket/289">http://tools.ietf.org/wg/httpbis/trac/ticket/289</a>&gt;: "Proxies don't 'understand' methods"
@@ -2019 +2023 @@
                   <li><tt>Grammar</tt>&nbsp;&nbsp;
                      <ul>
-                        <li><tt>Age</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.1"><b>3.1</b></a></li>
+                        <li><tt>Age</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.2"><b>3.1</b></a></li>
                         <li><tt>Cache-Control</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.3"><b>3.2</b></a></li>
                         <li><tt>cache-extension</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.4"><b>3.2</b></a></li>
                         <li><tt>cache-request-directive</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.5"><b>3.2.1</b></a></li>
                         <li><tt>cache-response-directive</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.6"><b>3.2.2</b></a></li>
-                        <li><tt>delta-seconds</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.2"><b>3.1</b></a></li>
+                        <li><tt>delta-seconds</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.1"><b>1.5</b></a></li>
                         <li><tt>Expires</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.7"><b>3.3</b></a></li>
                         <li><tt>extension-pragma</tt>&nbsp;&nbsp;<a href="#rfc.iref.g.10"><b>3.4</b></a></li>