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ffa16db02673ffa155ffb2649e72a935a1ff70f5Lennart Poettering<title>Apache's Handler Use - Apache HTTP Server</title>
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ffa16db02673ffa155ffb2649e72a935a1ff70f5Lennart Poettering<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>
ffa16db02673ffa155ffb2649e72a935a1ff70f5Lennart Poettering<p class="apache">Apache HTTP Server Version 2.1</p>
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ffa16db02673ffa155ffb2649e72a935a1ff70f5Lennart Poettering<div class="up"><a href="./"><img title="<-" alt="<-" src="/images/left.gif" /></a></div>
ffa16db02673ffa155ffb2649e72a935a1ff70f5Lennart Poettering<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></div><div id="page-content"><div id="preamble"><h1>Apache's Handler Use</h1>
5430f7f2bc7330f3088b894166bf3524a067e3d8Lennart Poettering <p>This document describes the use of Apache's Handlers.</p>
ffa16db02673ffa155ffb2649e72a935a1ff70f5Lennart Poettering<div id="quickview"><ul id="toc"><li><img alt="" src="/images/down.gif" /> <a href="#definition">What is a Handler</a></li>
ffa16db02673ffa155ffb2649e72a935a1ff70f5Lennart Poettering<li><img alt="" src="/images/down.gif" /> <a href="#examples">Examples</a></li>
ffa16db02673ffa155ffb2649e72a935a1ff70f5Lennart Poettering<li><img alt="" src="/images/down.gif" /> <a href="#programmer">Programmer's Note</a></li>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<h2><a name="definition" id="definition">What is a Handler</a></h2>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <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_imap.html">mod_imap</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>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <p>A "handler" is an internal Apache representation of the
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek action to be performed when a file is called. Generally, files
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek have implicit handlers, based on the file type. Normally, all
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek files are simply served by the server, but certain file types
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek are "handled" separately.</p>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <p>Apache 1.1 adds the ability to use handlers explicitly.
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek Based on either filename extensions or on location, handlers
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek can be specified without relation to file type. This is
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek advantageous both because it is a more elegant solution, and
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek because it also allows for both a type <strong>and</strong> a
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek handler to be associated with a file. (See also <a href="mod/mod_mime.html#multipleext">Files with Multiple
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <p>Handlers can either be built into the server or included in
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek a module, or they can be added with the <code class="directive"><a href="/mod/mod_actions.html#action">Action</a></code> directive. The
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek built-in handlers in the standard distribution are as
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <li><strong>default-handler</strong>: Send the file using the
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <code>default_handler()</code>, which is the handler used by
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek default to handle static content. (core)</li>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <li><strong>send-as-is</strong>: Send file with HTTP headers
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek as is. (<code class="module"><a href="/mod/mod_asis.html">mod_asis</a></code>)</li>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <li><strong>cgi-script</strong>: Treat the file as a CGI
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek script. (<code class="module"><a href="/mod/mod_cgi.html">mod_cgi</a></code>)</li>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <li><strong>imap-file</strong>: Parse as an imagemap rule
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek file. (<code class="module"><a href="/mod/mod_imap.html">mod_imap</a></code>)</li>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <li><strong>server-info</strong>: Get the server's
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek configuration information. (<code class="module"><a href="/mod/mod_info.html">mod_info</a></code>)</li>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <li><strong>server-status</strong>: Get the server's status
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek report. (<code class="module"><a href="/mod/mod_status.html">mod_status</a></code>)</li>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <li><strong>type-map</strong>: Parse as a type map file for
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek content negotiation. (<code class="module"><a href="/mod/mod_negotiation.html">mod_negotiation</a></code>)</li>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek </div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<h2><a name="examples" id="examples">Examples</a></h2>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <h3><a name="example1" id="example1">Modifying static content using a CGI script</a></h3>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <p>The following directives will cause requests for files with
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek the <code>html</code> extension to trigger the launch of the
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <code>footer.pl</code> CGI script.</p>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek Action add-footer /cgi-bin/footer.pl<br />
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek AddHandler add-footer .html
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <p>Then the CGI script is responsible for sending the
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek originally requested document (pointed to by the
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <code>PATH_TRANSLATED</code> environment variable) and making
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek whatever modifications or additions are desired.</p>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <h3><a name="example2" id="example2">Files with HTTP headers</a></h3>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <p>The following directives will enable the
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <code>send-as-is</code> handler, which is used for files which
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek contain their own HTTP headers. All files in the
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <code>/web/htdocs/asis/</code> directory will be processed by
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek the <code>send-as-is</code> handler, regardless of their
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek filename extensions.</p>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <Directory /web/htdocs/asis><br />
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek SetHandler send-as-is<br />
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek </Directory>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek </div><div class="top"><a href="#page-header"><img alt="top" src="/images/up.gif" /></a></div>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<h2><a name="programmer" id="programmer">Programmer's Note</a></h2>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <p>In order to implement the handler features, an addition has
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek been made to the <a href="developer/API.html">Apache API</a> that
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek you may wish to make use of. Specifically, a new record has
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek been added to the <code>request_rec</code> structure:</p>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek <p>If you wish to have your module engage a handler, you need
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek only to set <code>r->handler</code> to the name of the
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek handler at any time prior to the <code>invoke_handler</code>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek stage of the request. Handlers are implemented as they were
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek before, albeit using the handler name instead of a content
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek type. While it is not necessary, the naming convention for
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek handlers is to use a dash-separated word, with no slashes, so
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek as to not invade the media type name-space.</p>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<p class="apache">Maintained by the <a href="http://httpd.apache.org/docs-project/">Apache HTTP Server Documentation Project</a></p>
798d3a524ea57aaf40cb53858aaa45ec702f012dZbigniew Jędrzejewski-Szmek<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>