1 <?xml version="1.0" encoding="ISO-8859-1"?>
2 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
3 <html xmlns="http://www.w3.org/1999/xhtml" lang="en" xml:lang="en"><head><!--
4 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
5 This file is generated from xml source: DO NOT EDIT
6 XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
8 <title>mod_cache - Apache HTTP Server</title>
9 <link href="../style/css/manual.css" rel="stylesheet" media="all" type="text/css" title="Main stylesheet" />
10 <link href="../style/css/manual-loose-100pc.css" rel="alternate stylesheet" media="all" type="text/css" title="No Sidebar - Default font size" />
11 <link href="../style/css/manual-print.css" rel="stylesheet" media="print" type="text/css" />
12 <link href="../images/favicon.ico" rel="shortcut icon" /></head>
14 <div id="page-header">
15 <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p>
16 <p class="apache">Apache HTTP Server Version 2.1</p>
17 <img alt="" src="../images/feather.gif" /></div>
18 <div class="up"><a href="./"><img title="<-" alt="<-" src="../images/left.gif" /></a></div>
20 <a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs-project/">Documentation</a> > <a href="../">Version 2.1</a> > <a href="./">Modules</a></div>
21 <div id="page-content">
22 <div id="preamble"><h1>Apache Module mod_cache</h1>
24 <p><span>Available Languages: </span><a href="../en/mod/mod_cache.html" title="English"> en </a> |
25 <a href="../ko/mod/mod_cache.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
27 <table class="module"><tr><th><a href="module-dict.html#Description">Description:</a></th><td>Content cache keyed to URIs.</td></tr>
28 <tr><th><a href="module-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
29 <tr><th><a href="module-dict.html#ModuleIdentifier">Module Identifier:</a></th><td>cache_module</td></tr>
30 <tr><th><a href="module-dict.html#SourceFile">Source File:</a></th><td>mod_cache.c</td></tr></table>
34 This module is experimental. Documentation is still under development...
37 <p><code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code> implements an <a href="http://www.ietf.org/rfc/rfc2616.txt">RFC 2616</a> compliant HTTP
38 content cache that can be used to cache either local or proxied content.
39 <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code> requires the services of one or more storage
40 management modules. Two storage management modules are included in
41 the base Apache distribution:</p>
43 <dt><code class="module"><a href="../mod/mod_disk_cache.html">mod_disk_cache</a></code></dt>
44 <dd>implements a disk based storage manager.</dd>
46 <dt><code class="module"><a href="../mod/mod_mem_cache.html">mod_mem_cache</a></code></dt>
47 <dd>implements a memory based storage manager.
48 <code class="module"><a href="../mod/mod_mem_cache.html">mod_mem_cache</a></code> can be configured to operate in two
49 modes: caching open file descriptors or caching objects in heap storage.
50 <code class="module"><a href="../mod/mod_mem_cache.html">mod_mem_cache</a></code> can be used to cache locally generated content
51 or to cache backend server content for <code class="module"><a href="../mod/mod_proxy.html">mod_proxy</a></code> when
52 configured using <code class="directive"><a href="../mod/mod_proxy.html#proxypass">ProxyPass</a></code>
53 (aka <dfn>reverse proxy</dfn>)</dd>
56 <p>Content is stored in and retrieved from the cache using URI based keys. Content with
57 access protection is not cached.</p>
59 <div id="quickview"><h3 class="directives">Directives</h3>
61 <li><img alt="" src="../images/down.gif" /> <a href="#cachedefaultexpire">CacheDefaultExpire</a></li>
62 <li><img alt="" src="../images/down.gif" /> <a href="#cachedisable">CacheDisable</a></li>
63 <li><img alt="" src="../images/down.gif" /> <a href="#cacheenable">CacheEnable</a></li>
64 <li><img alt="" src="../images/down.gif" /> <a href="#cacheforcecompletion">CacheForceCompletion</a></li>
65 <li><img alt="" src="../images/down.gif" /> <a href="#cacheignorecachecontrol">CacheIgnoreCacheControl</a></li>
66 <li><img alt="" src="../images/down.gif" /> <a href="#cacheignorenolastmod">CacheIgnoreNoLastMod</a></li>
67 <li><img alt="" src="../images/down.gif" /> <a href="#cachelastmodifiedfactor">CacheLastModifiedFactor</a></li>
68 <li><img alt="" src="../images/down.gif" /> <a href="#cachemaxexpire">CacheMaxExpire</a></li>
72 <li><img alt="" src="../images/down.gif" /> <a href="#related">Related Modules and Directives</a></li>
73 <li><img alt="" src="../images/down.gif" /> <a href="#sampleconf">Sample Configuration</a></li>
75 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
77 <h2><a name="related" id="related">Related Modules and Directives</a></h2>
78 <table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td><ul><li><code class="module"><a href="../mod/mod_disk_cache.html">mod_disk_cache</a></code></li><li><code class="module"><a href="../mod/mod_mem_cache.html">mod_mem_cache</a></code></li></ul></td><td><ul><li><code class="directive"><a href="../mod/mod_disk_cache.html#cacheroot">CacheRoot</a></code></li><li><code class="directive"><a href="../mod/mod_disk_cache.html#cachesize">CacheSize</a></code></li><li><code class="directive"><a href="../mod/mod_disk_cache.html#cachegcinterval">CacheGcInterval</a></code></li><li><code class="directive"><a href="../mod/mod_disk_cache.html#cachedirlevels">CacheDirLevels</a></code></li><li><code class="directive"><a href="../mod/mod_disk_cache.html#cachedirlength">CacheDirLength</a></code></li><li><code class="directive"><a href="../mod/mod_disk_cache.html#cacheexpirycheck">CacheExpiryCheck</a></code></li><li><code class="directive"><a href="../mod/mod_disk_cache.html#cacheminfilesize">CacheMinFileSize</a></code></li><li><code class="directive"><a href="../mod/mod_disk_cache.html#cachemaxfilesize">CacheMaxFileSize</a></code></li><li><code class="directive"><a href="../mod/mod_disk_cache.html#cachetimemargin">CacheTimeMargin</a></code></li><li><code class="directive"><a href="../mod/mod_disk_cache.html#cachegcdaily">CacheGcDaily</a></code></li><li><code class="directive"><a href="../mod/mod_disk_cache.html#cachegcunused">CacheGcUnused</a></code></li><li><code class="directive"><a href="../mod/mod_disk_cache.html#cachegcclean">CacheGcClean</a></code></li><li><code class="directive"><a href="../mod/mod_disk_cache.html#cachegcmemusage">CacheGcMemUsage</a></code></li><li><code class="directive"><a href="../mod/mod_mem_cache.html#mcachesize">MCacheSize</a></code></li><li><code class="directive"><a href="../mod/mod_mem_cache.html#mcachemaxobjectcount">MCacheMaxObjectCount</a></code></li><li><code class="directive"><a href="../mod/mod_mem_cache.html#mcacheminobjectsize">MCacheMinObjectSize</a></code></li><li><code class="directive"><a href="../mod/mod_mem_cache.html#mcachemaxobjectsize">MCacheMaxObjectSize</a></code></li><li><code class="directive"><a href="../mod/mod_mem_cache.html#mcacheremovalalgorithm">MCacheRemovalAlgorithm</a></code></li><li><code class="directive"><a href="../mod/mod_mem_cache.html#mcachemaxstreamingbuffer">MCacheMaxStreamingBuffer</a></code></li></ul></td></tr></table>
79 </div><div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
81 <h2><a name="sampleconf" id="sampleconf">Sample Configuration</a></h2>
82 <div class="example"><h3>Sample httpd.conf</h3><p><code>
84 # Sample Cache Configuration<br />
86 LoadModule cache_module modules/mod_cache.so<br />
88 <IfModule mod_cache.c><br />
90 #LoadModule disk_cache_module modules/mod_disk_cache.so<br />
91 <IfModule mod_disk_cache.c><br />
93 CacheRoot c:/cacheroot<br />
95 CacheEnable disk /<br />
96 CacheDirLevels 5<br />
97 CacheDirLength 3<br />
99 </IfModule> <br />
101 LoadModule mem_cache_module modules/mod_mem_cache.so<br />
102 <IfModule mod_mem_cache.c><br />
103 <span class="indent">
104 CacheEnable mem /<br />
105 MCacheSize 4096<br />
106 MCacheMaxObjectCount 100<br />
107 MCacheMinObjectSize 1<br />
108 MCacheMaxObjectSize 2048<br />
110 </IfModule><br />
115 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
116 <div class="directive-section"><h2><a name="CacheDefaultExpire" id="CacheDefaultExpire">CacheDefaultExpire</a> <a name="cachedefaultexpire" id="cachedefaultexpire">Directive</a></h2>
117 <table class="directive">
118 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The default duration to cache a document when no expiry date is specified.</td></tr>
119 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CacheDefaultExpire <var>seconds</var></code></td></tr>
120 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>CacheDefaultExpire 3600 (one hour)</code></td></tr>
121 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
122 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
123 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_cache</td></tr>
125 <p>The <code class="directive">CacheDefaultExpire</code> directive specifies a default time,
126 in seconds, to cache a document if neither an expiry date nor last-modified date are provided
127 with the document. The value specified with the <code class="directive">CacheMaxExpire</code>
128 directive does <em>not</em> override this setting.</p>
130 <div class="example"><p><code>
131 CacheDefaultExpire 86400
135 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
136 <div class="directive-section"><h2><a name="CacheDisable" id="CacheDisable">CacheDisable</a> <a name="cachedisable" id="cachedisable">Directive</a></h2>
137 <table class="directive">
138 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Disable caching of specified URLs</td></tr>
139 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CacheDisable <var> url-string</var></code></td></tr>
140 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
141 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
142 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_cache</td></tr>
144 <p>The <code class="directive">CacheDisable</code> directive instructs
145 <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code> to <em>not</em> cache urls at or below
146 <var>url-string</var>.</p>
148 <div class="example"><h3>Example</h3><p><code>
149 CacheDisable /local_files
153 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
154 <div class="directive-section"><h2><a name="CacheEnable" id="CacheEnable">CacheEnable</a> <a name="cacheenable" id="cacheenable">Directive</a></h2>
155 <table class="directive">
156 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Enable caching of specified URLs using a specified storage
158 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CacheEnable <var>cache_type</var> <var>url-string</var></code></td></tr>
159 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
160 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
161 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_cache</td></tr>
163 <p>The <code class="directive">CacheEnable</code> directive instructs
164 <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code> to cache urls at or below
165 <var>url-string</var>. The cache storage manager is specified with the
166 <var>cache_type</var> argument. <var>cache_type</var> <code> mem</code>
167 instructs <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code> to use the memory based storage
168 manager implemented by <code class="module"><a href="../mod/mod_mem_cache.html">mod_mem_cache</a></code>.
169 <var>cache_type</var> <code>disk</code> instructs
170 <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code> to use the disk based storage manager
171 implemented by <code class="module"><a href="../mod/mod_disk_cache.html">mod_disk_cache</a></code>.
172 <var>cache_type</var> <code>fd</code> instructs
173 <code class="module"><a href="../mod/mod_cache.html">mod_cache</a></code> to use the file descriptor cache implemented
174 by <code class="module"><a href="../mod/mod_mem_cache.html">mod_mem_cache</a></code>.</p>
175 <p>In the event that the URL space overlaps between different
176 <code class="directive">CacheEnable</code> directives (as in the example below),
177 each possible storage manager will be run until the first one that
178 actually processes the request. The order in which the storage managers are
179 run is determined by the order of the <code class="directive">CacheEnable</code>
180 directives in the configuration file.</p>
182 <div class="example"><p><code>
183 CacheEnable mem /manual<br />
184 CacheEnable fd /images<br />
185 CacheEnable disk /<br />
189 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
190 <div class="directive-section"><h2><a name="CacheForceCompletion" id="CacheForceCompletion">CacheForceCompletion</a> <a name="cacheforcecompletion" id="cacheforcecompletion">Directive</a></h2>
191 <table class="directive">
192 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Percentage of document served, after which the server
193 will complete caching the file even if the request is cancelled.</td></tr>
194 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CacheForceCompletion <var>Percentage</var></code></td></tr>
195 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>CacheForceCompletion 60</code></td></tr>
196 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
197 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
198 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_cache</td></tr>
200 <p>Ordinarily, if a request is cancelled while the response is being
201 cached and delivered to the client the processing of the response will
202 stop and the cache entry will be removed. The
203 <code class="directive">CacheForceCompletion</code> directive specifies a
204 threshold beyond which the document will continue to be cached to
205 completion, even if the request is cancelled.</p>
207 <p>The threshold is a percentage specified as a value between
208 <code>1</code> and <code>100</code>. A value of <code>0</code>
209 specifies that the default be used. A value of <code>100</code>
210 will only cache documents that are served in their entirety. A value
211 between 60 and 90 is recommended.</p>
213 <div class="example"><p><code>
214 CacheForceCompletion 80
217 <div class="warning"><h3>Note:</h3>
218 This feature is currently <em>not</em> implemented.
222 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
223 <div class="directive-section"><h2><a name="CacheIgnoreCacheControl" id="CacheIgnoreCacheControl">CacheIgnoreCacheControl</a> <a name="cacheignorecachecontrol" id="cacheignorecachecontrol">Directive</a></h2>
224 <table class="directive">
225 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Ignore the fact that the client requested the content not be
227 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CacheIgnoreCacheControl On|Off</code></td></tr>
228 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>CacheIgnoreCacheControl Off</code></td></tr>
229 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
230 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
231 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_cache</td></tr>
233 <p>Ordinarily, documents with no-cache or no-store header values will not be stored in the cache.
234 The <code class="directive">CacheIgnoreCacheControl</code> directive allows this behavior to be overridden.
235 <code class="directive">CacheIgnoreCacheControl</code> On tells the server to attempt to cache the document
236 even if it contains no-cache or no-store header values. Documents requiring authorization will
237 <em>never</em> be cached.</p>
239 <div class="example"><p><code>
240 CacheIgnoreCacheControl On
244 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
245 <div class="directive-section"><h2><a name="CacheIgnoreNoLastMod" id="CacheIgnoreNoLastMod">CacheIgnoreNoLastMod</a> <a name="cacheignorenolastmod" id="cacheignorenolastmod">Directive</a></h2>
246 <table class="directive">
247 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>Ignore the fact that a response has no Last Modified
249 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CacheIgnoreNoLastMod On|Off</code></td></tr>
250 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>CacheIgnoreNoLastMod Off</code></td></tr>
251 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
252 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
253 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_cache</td></tr>
255 <p>Ordinarily, documents without a last-modified date are not cached.
256 Under some circumstances the last-modified date is removed (during
257 <code class="module"><a href="../mod/mod_include.html">mod_include</a></code> processing for example) or not provided
258 at all. The <code class="directive">CacheIgnoreNoLastMod</code> directive
259 provides a way to specify that documents without last-modified dates
260 should be considered for caching, even without a last-modified date.
261 If neither a last-modified date nor an expiry date are provided with
262 the document then the value specified by the
263 <code class="directive">CacheDefaultExpire</code> directive will be used to
264 generate an expiration date.</p>
266 <div class="example"><p><code>
267 CacheIgnoreNoLastMod On
271 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
272 <div class="directive-section"><h2><a name="CacheLastModifiedFactor" id="CacheLastModifiedFactor">CacheLastModifiedFactor</a> <a name="cachelastmodifiedfactor" id="cachelastmodifiedfactor">Directive</a></h2>
273 <table class="directive">
274 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The factor used to compute an expiry date based on the
275 LastModified date.</td></tr>
276 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CacheLastModifiedFactor <var>float</var></code></td></tr>
277 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>CacheLastModifiedFactor 0.1</code></td></tr>
278 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
279 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
280 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_cache</td></tr>
282 <p>In the event that a document does not provide an expiry date but does
283 provide a last-modified date, an expiry date can be calculated based on
284 the time since the document was last modified. The
285 <code class="directive">CacheLastModifiedFactor</code> directive specifies a
286 <var>factor</var> to be used in the generation of this expiry date
287 according to the following formula:
289 <code>expiry-period = time-since-last-modified-date * <var>factor</var>
290 expiry-date = current-date + expiry-period</code>
292 For example, if the document was last modified 10 hours ago, and
293 <var>factor</var> is 0.1 then the expiry-period will be set to
294 10*0.1 = 1 hour. If the current time was 3:00pm then the computed
295 expiry-date would be 3:00pm + 1hour = 4:00pm.
297 If the expiry-period would be longer than that set by
298 <code class="directive">CacheMaxExpire</code>, then the latter takes
301 <div class="example"><p><code>
302 CacheLastModifiedFactor 0.5
306 <div class="top"><a href="#page-header"><img alt="top" src="../images/up.gif" /></a></div>
307 <div class="directive-section"><h2><a name="CacheMaxExpire" id="CacheMaxExpire">CacheMaxExpire</a> <a name="cachemaxexpire" id="cachemaxexpire">Directive</a></h2>
308 <table class="directive">
309 <tr><th><a href="directive-dict.html#Description">Description:</a></th><td>The maximum time in seconds to cache a document</td></tr>
310 <tr><th><a href="directive-dict.html#Syntax">Syntax:</a></th><td><code>CacheMaxExpire <var>seconds</var></code></td></tr>
311 <tr><th><a href="directive-dict.html#Default">Default:</a></th><td><code>CacheMaxExpire 86400 (one day)</code></td></tr>
312 <tr><th><a href="directive-dict.html#Context">Context:</a></th><td>server config, virtual host</td></tr>
313 <tr><th><a href="directive-dict.html#Status">Status:</a></th><td>Experimental</td></tr>
314 <tr><th><a href="directive-dict.html#Module">Module:</a></th><td>mod_cache</td></tr>
316 <p>The <code class="directive">CacheMaxExpire</code> directive specifies the maximum number of
317 seconds for which cachable HTTP documents will be retained without checking the origin
318 server. Thus, documents will be out of date at most this number of seconds. This maximum
319 value is enforced even if an expiry date was supplied with the document.</p>
321 <div class="example"><p><code>
322 CacheMaxExpire 604800
327 <div class="bottomlang">
328 <p><span>Available Languages: </span><a href="../en/mod/mod_cache.html" title="English"> en </a> |
329 <a href="../ko/mod/mod_cache.html" hreflang="ko" rel="alternate" title="Korean"> ko </a></p>
330 </div><div id="footer">
331 <p class="apache">Copyright 1999-2004 The Apache Software Foundation.<br />Licensed under the <a href="http://www.apache.org/licenses/LICENSE-2.0">Apache License, Version 2.0</a>.</p>
332 <p class="menu"><a href="../mod/">Modules</a> | <a href="../mod/directives.html">Directives</a> | <a href="../faq/">FAQ</a> | <a href="../glossary.html">Glossary</a> | <a href="../sitemap.html">Sitemap</a></p></div>