Changeset 1740 for draft-ietf-httpbis/latest/p6-cache.html

Timestamp:

Jul 8, 2012, 11:15:03 AM (8 years ago)

Author:

julian.reschke@…

Message:

Work-in-progress: hyperlink header field definitions, plus minor editorial improvements (P2)

File:

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

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

@@ -794 +794 @@
          mechanisms, except in cases where it has direct impact on security. This is because different uses of the protocol require
          different error handling strategies; for example, a Web browser might wish to transparently recover from a response where
-         the Location header field doesn't parse according to the ABNF, whereby in a systems control protocol using HTTP, this type
-         of error recovery could lead to dangerous consequences.
+         the <a href="p2-semantics.html#header.location" class="smpl">Location</a> header field doesn't parse according to the ABNF, whereby in a systems control protocol using HTTP, this type of error recovery
+         could lead to dangerous consequences.
       </p>
       <h2 id="rfc.section.1.4"><a href="#rfc.section.1.4">1.4</a>&nbsp;<a id="notation" href="#notation">Syntax Notation</a></h2>
@@ -913 +913 @@
       <p id="rfc.section.2.2.p.5">Also, note that unsafe requests might invalidate already stored responses; see <a href="#invalidation.after.updates.or.deletions" title="Request Methods that Invalidate">Section&nbsp;2.6</a>.
       </p>
-      <p id="rfc.section.2.2.p.6">When more than one suitable response is stored, a cache <em class="bcp14">MUST</em> use the most recent response (as determined by the Date header field). It can also forward a request with "Cache-Control:
-         max-age=0" or "Cache-Control: no-cache" to disambiguate which response to use.
+      <p id="rfc.section.2.2.p.6">When more than one suitable response is stored, a cache <em class="bcp14">MUST</em> use the most recent response (as determined by the <a href="p2-semantics.html#header.date" class="smpl">Date</a> header field). It can also forward a request with "Cache-Control: max-age=0" or "Cache-Control: no-cache" to disambiguate
+         which response to use.
       </p>
       <p id="rfc.section.2.2.p.7">A cache that does not have a clock available <em class="bcp14">MUST NOT</em> use stored responses without revalidating them on every use. A cache, especially a shared cache, <em class="bcp14">SHOULD</em> use a mechanism, such as NTP <a href="#RFC1305" id="rfc.xref.RFC1305.1"><cite title="Network Time Protocol (Version 3) Specification, Implementation">[RFC1305]</cite></a>, to synchronize its clock with a reliable external standard.
@@ -951 +951 @@
          <li>If the max-age response cache directive (<a href="#cache-response-directive" title="Response Cache-Control Directives">Section&nbsp;3.2.2</a>) is present, use its value, or
          </li>
-         <li>If the <a href="#header.expires" class="smpl">Expires</a> response header field (<a href="#header.expires" id="rfc.xref.header.expires.3" title="Expires">Section&nbsp;3.3</a>) is present, use its value minus the value of the Date response header field, or
+         <li>If the <a href="#header.expires" class="smpl">Expires</a> response header field (<a href="#header.expires" id="rfc.xref.header.expires.3" title="Expires">Section&nbsp;3.3</a>) is present, use its value minus the value of the <a href="p2-semantics.html#header.date" class="smpl">Date</a> response header field, or
          </li>
          <li>Otherwise, no explicit expiration time is present in the response. A heuristic freshness lifetime might be applicable; see <a href="#heuristic.freshness" title="Calculating Heuristic Freshness">Section&nbsp;2.3.1.1</a>.
@@ -993 +993 @@
       </p>
       <ul class="empty">
-         <li>HTTP/1.1 requires origin servers to send a Date header field, if possible, with every response, giving the time at which the
-            response was generated. The term "date_value" denotes the value of the Date header field, in a form appropriate for arithmetic
-            operations. See <a href="p2-semantics.html#header.date" title="Date">Section 9.10</a> of <a href="#Part2" id="rfc.xref.Part2.5"><cite title="HTTP/1.1, part 2: Message Semantics, Payload and Content Negotiation">[Part2]</cite></a> for the definition of the Date header field, and for requirements regarding responses without it.
+         <li>HTTP/1.1 requires origin servers to send a <a href="p2-semantics.html#header.date" class="smpl">Date</a> header field, if possible, with every response, giving the time at which the response was generated. The term "date_value"
+            denotes the value of the Date header field, in a form appropriate for arithmetic operations. See <a href="p2-semantics.html#header.date" title="Date">Section 9.10</a> of <a href="#Part2" id="rfc.xref.Part2.5"><cite title="HTTP/1.1, part 2: Message Semantics, Payload and Content Negotiation">[Part2]</cite></a> for the definition of the Date header field, and for requirements regarding responses without it.
          </li>
       </ul>
@@ -1138 +1137 @@
          to keep their contents up-to-date.
       </p>
-      <p id="rfc.section.2.6.p.2">A cache <em class="bcp14">MUST</em> invalidate the effective Request URI (<a href="p1-messaging.html#effective.request.uri" title="Effective Request URI">Section 5.5</a> of <a href="#Part1" id="rfc.xref.Part1.13"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>) as well as the URI(s) in the Location and Content-Location response header fields (if present) when a non-error response
-         to a request with an unsafe method is received.
-      </p>
-      <p id="rfc.section.2.6.p.3">However, a cache <em class="bcp14">MUST NOT</em> invalidate a URI from a Location or Content-Location response header field if the host part of that URI differs from the host
-         part in the effective request URI (<a href="p1-messaging.html#effective.request.uri" title="Effective Request URI">Section 5.5</a> of <a href="#Part1" id="rfc.xref.Part1.14"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>). This helps prevent denial of service attacks.
+      <p id="rfc.section.2.6.p.2">A cache <em class="bcp14">MUST</em> invalidate the effective Request URI (<a href="p1-messaging.html#effective.request.uri" title="Effective Request URI">Section 5.5</a> of <a href="#Part1" id="rfc.xref.Part1.13"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>) as well as the URI(s) in the <a href="p2-semantics.html#header.location" class="smpl">Location</a> and <a href="p2-semantics.html#header.content-location" class="smpl">Content-Location</a> response header fields (if present) when a non-error response to a request with an unsafe method is received.
+      </p>
+      <p id="rfc.section.2.6.p.3">However, a cache <em class="bcp14">MUST NOT</em> invalidate a URI from a <a href="p2-semantics.html#header.location" class="smpl">Location</a> or <a href="p2-semantics.html#header.content-location" class="smpl">Content-Location</a> response header field if the host part of that URI differs from the host part in the effective request URI (<a href="p1-messaging.html#effective.request.uri" title="Effective Request URI">Section 5.5</a> of <a href="#Part1" id="rfc.xref.Part1.14"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>). This helps prevent denial of service attacks.
       </p>
       <p id="rfc.section.2.6.p.4">A cache <em class="bcp14">MUST</em> invalidate the effective request URI (<a href="p1-messaging.html#effective.request.uri" title="Effective Request URI">Section 5.5</a> of <a href="#Part1" id="rfc.xref.Part1.15"><cite title="HTTP/1.1, part 1: URIs, Connections, and Message Parsing">[Part1]</cite></a>) when it receives a non-error response to a request with a method whose safety is unknown.
@@ -1184 +1181 @@
       </p>
       <p id="rfc.section.2.8.p.5">The stored response with matching selecting header fields is known as the selected response.</p>
-      <p id="rfc.section.2.8.p.6">If multiple selected responses are available, the most recent response (as determined by the Date header field) is used; see <a href="#constructing.responses.from.caches" title="Constructing Responses from Caches">Section&nbsp;2.2</a>.
+      <p id="rfc.section.2.8.p.6">If multiple selected responses are available, the most recent response (as determined by the <a href="p2-semantics.html#header.date" class="smpl">Date</a> header field) is used; see <a href="#constructing.responses.from.caches" title="Constructing Responses from Caches">Section&nbsp;2.2</a>.
       </p>
       <p id="rfc.section.2.8.p.7">If no selected response is available, the cache can forward the presented request to the origin server in a conditional request;
@@ -1305 +1302 @@
       <div id="rfc.iref.n.3"></div>
       <h4 id="rfc.section.3.2.1.6"><a href="#rfc.section.3.2.1.6">3.2.1.6</a>&nbsp;<a id="cache-request-directive.no-transform" href="#cache-request-directive.no-transform">no-transform</a></h4>
-      <p id="rfc.section.3.2.1.6.p.1">The no-transform request directive indicates that an intermediary (whether or not it implements a cache) <em class="bcp14">MUST NOT</em> change the Content-Encoding, <a href="p5-range.html#header.content-range" class="smpl">Content-Range</a> or Content-Type request header fields, nor the request representation.
+      <p id="rfc.section.3.2.1.6.p.1">The no-transform request directive indicates that an intermediary (whether or not it implements a cache) <em class="bcp14">MUST NOT</em> change the <a href="p2-semantics.html#header.content-encoding" class="smpl">Content-Encoding</a>, <a href="p5-range.html#header.content-range" class="smpl">Content-Range</a> or <a href="p2-semantics.html#header.content-type" class="smpl">Content-Type</a> request header fields, nor the request representation.
       </p>
       <div id="rfc.iref.c.13"></div>
@@ -1421 +1418 @@
       <div id="rfc.iref.n.6"></div>
       <h4 id="rfc.section.3.2.2.9"><a href="#rfc.section.3.2.2.9">3.2.2.9</a>&nbsp;<a id="cache-response-directive.no-transform" href="#cache-response-directive.no-transform">no-transform</a></h4>
-      <p id="rfc.section.3.2.2.9.p.1">The no-transform response directive indicates that an intermediary (regardless of whether it implements a cache) <em class="bcp14">MUST NOT</em> change the Content-Encoding, <a href="p5-range.html#header.content-range" class="smpl">Content-Range</a> or Content-Type response header fields, nor the response representation.
+      <p id="rfc.section.3.2.2.9.p.1">The no-transform response directive indicates that an intermediary (regardless of whether it implements a cache) <em class="bcp14">MUST NOT</em> change the <a href="p2-semantics.html#header.content-encoding" class="smpl">Content-Encoding</a>, <a href="p5-range.html#header.content-range" class="smpl">Content-Range</a> or <a href="p2-semantics.html#header.content-type" class="smpl">Content-Type</a> response header fields, nor the response representation.
       </p>
       <h3 id="rfc.section.3.2.3"><a href="#rfc.section.3.2.3">3.2.3</a>&nbsp;<a id="cache.control.extensions" href="#cache.control.extensions">Cache Control Extensions</a></h3>
@@ -1592 +1589 @@
       </ul>
       <p id="rfc.section.3.6.p.9">If an implementation sends a message with one or more Warning header fields to a receiver whose version is HTTP/1.0 or lower,
-         then the sender <em class="bcp14">MUST</em> include in each warning-value a warn-date that matches the Date header field in the message.
-      </p>
-      <p id="rfc.section.3.6.p.10">If a system receives a message with a warning-value that includes a warn-date, and that warn-date is different from the Date
-         value in the response, then that warning-value <em class="bcp14">MUST</em> be deleted from the message before storing, forwarding, or using it. (preventing the consequences of naive caching of Warning
+         then the sender <em class="bcp14">MUST</em> include in each warning-value a warn-date that matches the <a href="p2-semantics.html#header.date" class="smpl">Date</a> header field in the message.
+      </p>
+      <p id="rfc.section.3.6.p.10">If a system receives a message with a warning-value that includes a warn-date, and that warn-date is different from the <a href="p2-semantics.html#header.date" class="smpl">Date</a> value in the response, then that warning-value <em class="bcp14">MUST</em> be deleted from the message before storing, forwarding, or using it. (preventing the consequences of naive caching of Warning
          header fields.) If all of the warning-values are deleted for this reason, the Warning header field <em class="bcp14">MUST</em> be deleted as well.
       </p>
@@ -1970 +1966 @@
       <p id="rfc.section.A.p.1">Make the specified age calculation algorithm less conservative. (<a href="#age.calculations" title="Calculating Age">Section&nbsp;2.3.2</a>)
       </p>
-      <p id="rfc.section.A.p.2">Remove requirement to consider Content-Location in successful responses in order to determine the appropriate response to
-         use. (<a href="#validation.model" title="Validation Model">Section&nbsp;2.4</a>)
+      <p id="rfc.section.A.p.2">Remove requirement to consider <a href="p2-semantics.html#header.content-location" class="smpl">Content-Location</a> in successful responses in order to determine the appropriate response to use. (<a href="#validation.model" title="Validation Model">Section&nbsp;2.4</a>)
       </p>
       <p id="rfc.section.A.p.3">Clarify denial of service attack avoidance requirement. (<a href="#invalidation.after.updates.or.deletions" title="Request Methods that Invalidate">Section&nbsp;2.6</a>)