mirror of
https://github.com/apache/httpd.git
synced 2025-07-19 02:42:17 +03:00
5e8ac7dd19
git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@96159 13f79535-47bb-0310-9956-ffa450edef68
160 lines
11 KiB
Plaintext
160 lines
11 KiB
Plaintext
<html xmlns="http://www.w3.org/TR/xhtml1/strict"><head><!--
|
|
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
|
|
This file is generated from xml source: DO NOT EDIT
|
|
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
|
|
--><title>mod_expires- Apache HTTP Server</title><link href="../style/manual.css" type="text/css" rel="stylesheet"/></head><body><blockquote><div align="center"><img src="../images/sub.gif" alt="[APACHE DOCUMENTATION]"/><h3>Apache HTTP Server Version 2.0</h3></div><h1 align="center">Apache Module mod_expires</h1><table cellspacing="1" cellpadding="0" bgcolor="#cccccc"><tr><td><table bgcolor="#ffffff"><tr><td nowrap="nowrap" valign="top"><span class="help">Description:</span></td><td>Generation of
|
|
<code>Expires</code> HTTP headers according to user-specified
|
|
criteria</td></tr><tr><td nowrap="nowrap"><a href="module-dict.html#Status" class="help">Status:</a></td><td>Extension</td></tr><tr><td nowrap="nowrap"><a href="module-dict.html#ModuleIdentifier" class="help">Module Identifier:</a></td><td>expires_module</td></tr></table></td></tr></table><h2>Summary</h2>
|
|
<p>This module controls the setting of the <code>Expires</code>
|
|
HTTP header in server responses. The expiration date can set to
|
|
be relative to either the time the source file was last
|
|
modified, or to the time of the client access.</p>
|
|
|
|
<p>The <code>Expires</code> HTTP header is an instruction to
|
|
the client about the document's validity and persistence. If
|
|
cached, the document may be fetched from the cache rather than
|
|
from the source until this time has passed. After that, the
|
|
cache copy is considered "expired" and invalid, and a new copy
|
|
must be obtained from the source.</p>
|
|
<h2>Directives</h2><ul><li><a href="#expiresactive">ExpiresActive</a></li><li><a href="#expiresbytype">ExpiresByType</a></li><li><a href="#expiresdefault">ExpiresDefault</a></li></ul><h2><a name="AltSyn">Alternate Interval
|
|
Syntax</a></h2>
|
|
|
|
<p>The <a href="#expiresdefault" class="directive"><code class="directive">ExpiresDefault</code></a> and
|
|
<a href="#expiresbytype" class="directive"><code class="directive">ExpiresByType</code></a> directives
|
|
can also be defined in a more readable syntax of the form:</p>
|
|
|
|
<blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
|
|
ExpiresDefault "<base> [plus] {<num>
|
|
<type>}*"<br>
|
|
ExpiresByType type/encoding "<base> [plus]
|
|
{<num> <type>}*"
|
|
</code></td></tr></table></blockquote>
|
|
|
|
<p>where <base> is one of:</p>
|
|
|
|
<ul>
|
|
<li><code>access</code></li>
|
|
|
|
<li><code>now</code> (equivalent to
|
|
'<code>access</code>')</li>
|
|
|
|
<li><code>modification</code></li>
|
|
</ul>
|
|
|
|
<p>The '<code>plus</code>' keyword is optional. <num>
|
|
should be an integer value [acceptable to <code>atoi()</code>],
|
|
and <type> is one of:</p>
|
|
|
|
<ul>
|
|
<li><code>years</code></li>
|
|
|
|
<li><code>months</code></li>
|
|
|
|
<li><code>weeks</code></li>
|
|
|
|
<li><code>days</code></li>
|
|
|
|
<li><code>hours</code></li>
|
|
|
|
<li><code>minutes</code></li>
|
|
|
|
<li><code>seconds</code></li>
|
|
</ul>
|
|
|
|
<p>For example, any of the following directives can be used to
|
|
make documents expire 1 month after being accessed, by
|
|
default:</p>
|
|
|
|
<blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
|
|
ExpiresDefault "access plus 1 month"<br>
|
|
ExpiresDefault "access plus 4 weeks"<br>
|
|
ExpiresDefault "access plus 30 days"
|
|
</code></td></tr></table></blockquote>
|
|
|
|
<p>The expiry time can be fine-tuned by adding several
|
|
'<num> <type>' clauses:</p>
|
|
|
|
<blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
|
|
ExpiresByType text/html "access plus 1 month 15
|
|
days 2 hours"<br>
|
|
ExpiresByType image/gif "modification plus 5 hours 3
|
|
minutes"
|
|
</code></td></tr></table></blockquote>
|
|
|
|
<p>Note that if you use a modification date based setting, the
|
|
Expires header will <strong>not</strong> be added to content
|
|
that does not come from a file on disk. This is due to the fact
|
|
that there is no modification time for such content.</p>
|
|
<hr/><h2><a name="ExpiresActive">ExpiresActive</a> <a name="expiresactive">Directive</a></h2><table cellpadding="1" cellspacing="0" border="0" bgcolor="#cccccc"><tr><td><table bgcolor="#ffffff"><tr><td nowrap="nowrap"><strong>Description: </strong></td><td>Enables generation of Expires headers</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>ExpiresActive On|Off</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Context" class="help">Context:</a></td><td>server config, virtual host, directory, .htaccess</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Override" class="help">Override:</a></td><td>Indexes</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Status" class="help">Status:</a></td><td>Extension</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Module" class="help">Module:</a></td><td>mod_expires</td></tr></table></td></tr></table>
|
|
<p>This directive enables or disables the generation of the
|
|
<code>Expires</code> header for the document realm in question.
|
|
(That is, if found in an <code>.htaccess</code> file, for
|
|
instance, it applies only to documents generated from that
|
|
directory.) If set to <em><code>Off</code></em>, no
|
|
<code>Expires</code> header will be generated for any document
|
|
in the realm (unless overridden at a lower level, such as an
|
|
<code>.htaccess</code> file overriding a server config file).
|
|
If set to <em><code>On</code></em>, the header will be added to
|
|
served documents according to the criteria defined by the
|
|
<a href="#expiresbytype" class="directive"><code class="directive">ExpiresByType</code></a> and
|
|
<a href="#expiresdefault" class="directive"><code class="directive">ExpiresDefault</code></a> directives
|
|
(<em>q.v.</em>).</p>
|
|
|
|
<p>Note that this directive does not guarantee that an
|
|
<code>Expires</code> header will be generated. If the criteria
|
|
aren't met, no header will be sent, and the effect will be as
|
|
though this directive wasn't even specified.</p>
|
|
<hr/><h2><a name="ExpiresByType">ExpiresByType</a> <a name="expiresbytype">Directive</a></h2><table cellpadding="1" cellspacing="0" border="0" bgcolor="#cccccc"><tr><td><table bgcolor="#ffffff"><tr><td nowrap="nowrap"><strong>Description: </strong></td><td>Value of the Expires header configured
|
|
by MIME type</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>ExpiresByType
|
|
<em>MIME-type <code>seconds</em></td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Context" class="help">Context:</a></td><td>server config, virtual host, directory, .htaccess</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Override" class="help">Override:</a></td><td>Indexes</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Status" class="help">Status:</a></td><td>Extension</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Module" class="help">Module:</a></td><td>mod_expires</td></tr></table></td></tr></table>
|
|
<p>This directive defines the value of the <code>Expires</code>
|
|
header generated for documents of the specified type
|
|
(<em>e.g.</em>, <code>text/html</code>). The second argument
|
|
sets the number of seconds that will be added to a base time to
|
|
construct the expiration date.</p>
|
|
|
|
<p>The base time is either the last modification time of the
|
|
file, or the time of the client's access to the document. Which
|
|
should be used is specified by the
|
|
<code><em><code></em></code> field; <strong>M</strong>
|
|
means that the file's last modification time should be used as
|
|
the base time, and <strong>A</strong> means the client's access
|
|
time should be used.</p>
|
|
|
|
<p>The difference in effect is subtle. If <em>M</em> is used,
|
|
all current copies of the document in all caches will expire at
|
|
the same time, which can be good for something like a weekly
|
|
notice that's always found at the same URL. If <em>A</em> is
|
|
used, the date of expiration is different for each client; this
|
|
can be good for image files that don't change very often,
|
|
particularly for a set of related documents that all refer to
|
|
the same images (<em>i.e.</em>, the images will be accessed
|
|
repeatedly within a relatively short timespan).</p>
|
|
|
|
<p><strong>Example:</strong></p>
|
|
<blockquote><table cellpadding="10"><tr><td bgcolor="#eeeeee"><code>
|
|
# enable expirations<br>
|
|
ExpiresActive On<br>
|
|
# expire GIF images after a month in the client's cache<br>
|
|
ExpiresByType image/gif A2592000<br>
|
|
# HTML documents are good for a week from the time they were changed<br>
|
|
ExpiresByType text/html M604800
|
|
</code></td></tr></table></blockquote>
|
|
|
|
<p>Note that this directive only has effect if
|
|
<code>ExpiresActive On</code> has been specified. It overrides,
|
|
for the specified MIME type <em>only</em>, any expiration date
|
|
set by the <a href="#expiresdefault" class="directive"><code class="directive">ExpiresDefault</code></a>
|
|
directive.</p>
|
|
|
|
<p>You can also specify the expiration time calculation using
|
|
an <a href="#AltSyn">alternate syntax</a>, described earlier in
|
|
this document.</p>
|
|
<hr/><h2><a name="ExpiresDefault">ExpiresDefault</a> <a name="expiresdefault">Directive</a></h2><table cellpadding="1" cellspacing="0" border="0" bgcolor="#cccccc"><tr><td><table bgcolor="#ffffff"><tr><td nowrap="nowrap"><strong>Description: </strong></td><td>Default algorithm for calculating expiration time</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Syntax" class="help">Syntax:</a></td><td>ExpiresDefault <em><code>seconds</em></td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Context" class="help">Context:</a></td><td>server config, virtual host, directory, .htaccess</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Override" class="help">Override:</a></td><td>Indexes</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Status" class="help">Status:</a></td><td>Extension</td></tr><tr><td nowrap="nowrap"><a href="directive-dict.html#Module" class="help">Module:</a></td><td>mod_expires</td></tr></table></td></tr></table>
|
|
<p>This directive sets the default algorithm for calculating the
|
|
expiration time for all documents in the affected realm. It can be
|
|
overridden on a type-by-type basis by the <a href="#expiresbytype" class="directive"><code class="directive">ExpiresByType</code></a> directive. See the
|
|
description of that directive for details about the syntax of the
|
|
argument, and the <a href="#AltSyn">alternate syntax</a>
|
|
description as well.</p>
|
|
<hr/></blockquote><h3 align="center">Apache HTTP Server Version 2.0</h3><a href="./"><img src="../images/index.gif" alt="Index"/></a><a href="../"><img src="../images/home.gif" alt="Home"/></a></body></html> |