r22 - trunk/varnish-doc/en/varnish-specification
des at projects.linpro.no
des at projects.linpro.no
Thu Feb 23 15:32:11 CET 2006
Author: des
Date: 2006-02-23 15:32:11 +0100 (Thu, 23 Feb 2006)
New Revision: 22
Modified:
trunk/varnish-doc/en/varnish-specification/article.xml
Log:
Discuss expiry and cacheability.
Modified: trunk/varnish-doc/en/varnish-specification/article.xml
===================================================================
--- trunk/varnish-doc/en/varnish-specification/article.xml 2006-02-23 14:29:05 UTC (rev 21)
+++ trunk/varnish-doc/en/varnish-specification/article.xml 2006-02-23 14:32:11 UTC (rev 22)
@@ -26,7 +26,7 @@
<para>The key words “MUST”, “MUST NOT”, “REQUIRED”, “SHALL”,
“SHALL NOT”, “SHOULD”, “SHOULD NOT”, “RECOMMENDED”, “MAY”, and
“OPTIONAL” in this document are to be interpreted as described
- in IETF RFC 2119.</para>
+ in <xref linkend="RFC2119"/>.</para>
<para>XXX at this time, the above is incorrect because we
started out using MoSCoW prioritisation before realising it was
@@ -175,7 +175,7 @@
<title>Internal documentation</title>
<para>The internal documentation consists of:</para>
- <orderedlist>
+ <itemizedlist>
<listitem>
<para>Code comments.</para>
</listitem>
@@ -197,14 +197,14 @@
documentation either in the project Wiki or in DocBook XML
format.</para>
</listitem>
- </orderedlist>
+ </itemizedlist>
</section>
<section>
<title>External documentation</title>
<para>The external documentation consists of:</para>
- <orderedlist>
+ <itemizedlist>
<listitem>
<para>Manual pages for all daemons and command-line
tools.</para>
@@ -220,7 +220,7 @@
<listitem>
<para>Sample configuration files.</para>
</listitem>
- </orderedlist>
+ </itemizedlist>
</section>
</section>
</section>
@@ -249,7 +249,7 @@
requests from both IPv4 and IPv6 clients.</para>
<para>Varnish must, in general terms, handle these requests in
- conformance with IETF RFC 2616.</para>
+ conformance with <xref linkend="RFC2616"/>.</para>
<para>Varnish may handle HTTP/0.9 requests in any way it sees
fit, including but not limited to returning a 400 Bad Request
@@ -258,19 +258,21 @@
<para>Varnish must use HTTP/1.1 in its communications with the
content servers.</para>
- <para>Varnish may deviate from IETF RFC 2616 when this is
- necessary for interoperability with non-conforming clients or
- content servers.</para>
+ <para>Varnish may deviate from <xref linkend="RFC2616"/> when
+ this is necessary for interoperability with non-conforming
+ clients or content servers.</para>
- <para>Varnish may deviate from IETF RFC 2616 in cases where
- doing so provides a considerable performance advantage without
- causing significant harm to interoperability. Any such
- deviation must be documented.</para>
+ <para>Varnish may deviate from <xref linkend="RFC2616"/> in
+ cases where doing so provides a considerable performance
+ advantage without causing significant harm to
+ interoperability. Any such deviation must be
+ documented.</para>
<para>In its communications with clients, Varnish must
- interpret IETF RFC 2616 as if it were an origin server. In
- its communications with content servers, Varnish must
- interpret IETF RFC 2616 as if it were a cache.</para>
+ interpret <xref linkend="RFC2616"/> as if it were an origin
+ server. In its communications with content servers, Varnish
+ must interpret <xref linkend="RFC2616"/> as if it were a
+ cache.</para>
</section>
<section>
@@ -323,18 +325,81 @@
</section>
<section>
- <title>Expiry</title>
+ <title>Cacheability</title>
- <para>If a cached document has an expiry time associated with
- it, and that time has not yet been reached, Varnish may serve
- the document from cache without contacting the content
- server.</para>
+ <para>A request which includes authentication headers must not
+ be served from cache.</para>
+
+ <para>Varnish must interpret Cache-Control directives received
+ from content servers as follows:</para>
+
+ <itemizedlist>
+ <listitem>
+ <para>public: the document will be cached even if
+ authentication headers are present.</para>
+ </listitem>
+ <listitem>
+ <para>private: the document will not be cached, since
+ Varnish is a shared cache.</para>
+ </listitem>
+ <listitem>
+ <para>no-cache: the document will not be cached.</para>
+ </listitem>
+ <listitem>
+ <para>no-store: XXX</para>
+ </listitem>
+ <listitem>
+ <para>s-maxage: overrides max-age, since Varnish is a
+ shared cache.</para>
+ </listitem>
+ <listitem>
+ <para>max-age: overrides the Expires header.</para>
+ </listitem>
+ <listitem>
+ <para>min-fresh: ignored.</para>
+ </listitem>
+ <listitem>
+ <para>max-stale: ignored.</para>
+ </listitem>
+ <listitem>
+ <para>only-if-cached: ignored.</para>
+ </listitem>
+ <listitem>
+ <para>must-revalidate: as specified in <xref
+ linkend="RFC2616"/> §14.9.4.</para>
+ </listitem>
+ <listitem>
+ <para>proxy-revalidate: as must-revalidate.</para>
+ </listitem>
+ <listitem>
+ <para>no-transform: ignored.</para>
+ </listitem>
+ </itemizedlist>
+
+ <para>Varnish must ignore Cache-Control directives received
+ from clients.</para>
</section>
<section>
- <title>Non-cacheable content</title>
+ <title>Expiry</title>
- <para>XXX</para>
+ <para>If a content server returns a document with a s-maxage
+ directive, Varnish will set the expiry time for that document
+ to the time of the request plus the number of seconds
+ specified by the directive.</para>
+
+ <para>If a content server returns a document with no s-maxage
+ directive but a max-age directive, Varnish will set the expiry
+ time for that document to the time of the request plus the
+ number of seconds specified by the max-age directive.</para>
+
+ <para>If a content server returns a document with no s-maxage
+ or max-age directive but an Expires header, Varnish must set
+ the expiry time for that document to the value specified by
+ the Expires header.</para>
+
+ <para>When sending a document to a client, Varnish must set
+ the Expires header to the document's expiry time.</para>
</section>
</section>
@@ -422,7 +487,7 @@
<para>Varnish must provide the data necessary to compute
lifetime totals and sliding averages for the following:</para>
- <orderedlist>
+ <itemizedlist>
<listitem>
<para>Total size of documents served to clients</para>
</listitem>
@@ -481,13 +546,13 @@
<listitem>
<para>XXX length of request queues</para>
</listitem>
- </orderedlist>
+ </itemizedlist>
<para>In addition, Varnish must provide the data necessary to
compute the average, median and distribution for the
following:</para>
- <orderedlist>
+ <itemizedlist>
<listitem>
<para>Size of documents served, per unique document</para>
</listitem>
@@ -501,7 +566,9 @@
<para>Requests per client connection</para>
</listitem>
<listitem>
- <para>Client request completion time</para>
+ <para>Client request completion time, broken down by
+ request type (HEAD / GET), cache status (HIT / MISS) and
+ outcome (200, 404...)</para>
</listitem>
<listitem>
<para>Content server connection duration</para>
@@ -510,12 +577,14 @@
<para>Requests per content server connection</para>
</listitem>
<listitem>
- <para>Content server request completion time</para>
+ <para>Content server request completion time, broken down
+ by request type (HEAD / GET) and outcome (200,
+ 404...)</para>
</listitem>
<listitem>
<para>XXX time spent in request queues</para>
</listitem>
- </orderedlist>
+ </itemizedlist>
</section>
</section>
@@ -529,7 +598,7 @@
<para>The following monitoring operations must be
supported:</para>
- <orderedlist>
+ <itemizedlist>
<listitem>
<para>Cache status of individual documents</para>
</listitem>
@@ -547,11 +616,11 @@
<listitem>
<para>XXX</para>
</listitem>
- </orderedlist>
+ </itemizedlist>
<para>The following tuning operations must be supported:</para>
- <orderedlist>
+ <itemizedlist>
<listitem>
<para>Forced invalidation of individual documents</para>
</listitem>
@@ -561,7 +630,7 @@
<listitem>
<para>XXX</para>
</listitem>
- </orderedlist>
+ </itemizedlist>
</section>
<section>
<title>Clustering</title>
@@ -714,5 +783,6 @@
<bibliomixed id="RFC2186"/>
<bibliomixed id="RFC2616"/>
<bibliomixed id="RFC2756"/>
+ <bibliomixed id="RFC3507"/>
</bibliography>
</article>
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