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<title>Apache's Handler Use - Apache HTTP Server</title>
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<p class="apache">Apache HTTP Server Version 2.3</p>
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<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="./">Version 2.3</a></div><div id="page-content"><div id="preamble"><h1>Apache's Handler Use</h1>
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<p><span>Available Languages: </span><a href="/en/handler.html" title="English"> en </a> |
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<p>This document describes the use of Apache's Handlers.</p>
</div>
<div id="quickview"><ul id="toc"><li><img alt="" src="/images/down.gif" /> <a href="#definition">What is a Handler</a></li>
</ul></div>
<div class="section">
<h2><a name="definition" id="definition">What is a Handler</a></h2>
<table class="related"><tr><th>Related Modules</th><th>Related Directives</th></tr><tr><td><ul><li><code class="module"><a href="/mod/mod_actions.html">mod_actions</a></code></li><li><code class="module"><a href="/mod/mod_asis.html">mod_asis</a></code></li><li><code class="module"><a href="/mod/mod_cgi.html">mod_cgi</a></code></li><li><code class="module"><a href="/mod/mod_imagemap.html">mod_imagemap</a></code></li><li><code class="module"><a href="/mod/mod_info.html">mod_info</a></code></li><li><code class="module"><a href="/mod/mod_mime.html">mod_mime</a></code></li><li><code class="module"><a href="/mod/mod_negotiation.html">mod_negotiation</a></code></li><li><code class="module"><a href="/mod/mod_status.html">mod_status</a></code></li></ul></td><td><ul><li><code class="directive"><a href="/mod/mod_actions.html#action">Action</a></code></li><li><code class="directive"><a href="/mod/mod_mime.html#addhandler">AddHandler</a></code></li><li><code class="directive"><a href="/mod/mod_mime.html#removehandler">RemoveHandler</a></code></li><li><code class="directive"><a href="/mod/core.html#sethandler">SetHandler</a></code></li></ul></td></tr></table>
<p>A "handler" is an internal Apache representation of the
action to be performed when a file is called. Generally, files
have implicit handlers, based on the file type. Normally, all
files are simply served by the server, but certain file types
are "handled" separately.</p>
<p>Handlers may also be configured explicitly,
based on either filename extensions or on location,
without relation to file type. This is
advantageous both because it is a more elegant solution, and
because it also allows for both a type <strong>and</strong> a
handler to be associated with a file. (See also <a href="mod/mod_mime.html#multipleext">Files with Multiple
Extensions</a>.)</p>
<p>Handlers can either be built into the server or included in
a module, or they can be added with the <code class="directive"><a href="/mod/mod_actions.html#action">Action</a></code> directive. The
built-in handlers in the standard distribution are as
follows:</p>
<ul>
<li><strong>default-handler</strong>: Send the file using the
<code>default_handler()</code>, which is the handler used by
default to handle static content. (core)</li>
<li><strong>send-as-is</strong>: Send file with HTTP headers
<li><strong>cgi-script</strong>: Treat the file as a CGI
<li><strong>imap-file</strong>: Parse as an imagemap rule
<li><strong>server-info</strong>: Get the server's
configuration information. (<code class="module"><a href="/mod/mod_info.html">mod_info</a></code>)</li>
<li><strong>server-status</strong>: Get the server's status
<li><strong>type-map</strong>: Parse as a type map file for
content negotiation. (<code class="module"><a href="/mod/mod_negotiation.html">mod_negotiation</a></code>)</li>
</ul>
<div class="section">
<h2><a name="examples" id="examples">Examples</a></h2>
<h3><a name="example1" id="example1">Modifying static content using a CGI script</a></h3>
<p>The following directives will cause requests for files with
the <code>html</code> extension to trigger the launch of the
<div class="example"><p><code>
AddHandler add-footer .html
</code></p></div>
<p>Then the CGI script is responsible for sending the
originally requested document (pointed to by the
<code>PATH_TRANSLATED</code> environment variable) and making
whatever modifications or additions are desired.</p>
<h3><a name="example2" id="example2">Files with HTTP headers</a></h3>
<p>The following directives will enable the
<code>send-as-is</code> handler, which is used for files which
contain their own HTTP headers. All files in the
the <code>send-as-is</code> handler, regardless of their
filename extensions.</p>
<div class="example"><p><code>
SetHandler send-as-is<br />
</Directory>
</code></p></div>
<div class="section">
<h2><a name="programmer" id="programmer">Programmer's Note</a></h2>
<p>In order to implement the handler features, an addition has
you may wish to make use of. Specifically, a new record has
been added to the <code>request_rec</code> structure:</p>
<div class="example"><p><code>
char *handler
</code></p></div>
<p>If you wish to have your module engage a handler, you need
only to set <code>r->handler</code> to the name of the
handler at any time prior to the <code>invoke_handler</code>
stage of the request. Handlers are implemented as they were
before, albeit using the handler name instead of a content
type. While it is not necessary, the naming convention for
handlers is to use a dash-separated word, with no slashes, so
as to not invade the media type name-space.</p>
</div></div>
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<p><span>Available Languages: </span><a href="/en/handler.html" title="English"> en </a> |
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<p class="apache">Copyright 2006 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>
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