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      --><title>Filters - 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">Filters</h1>
    <p>This document describes the use of filters in Apache.</p>
  <hr/><h2><a name="filters">Filters</a></h2>
    
    <table border="1"><tr><td valign="top"><strong>Related Modules</strong><br/><br/><code><a href="./mod/mod_deflate.html">mod_deflate</a></code><br/><code><a href="./mod/mod_ext_filter.html">mod_ext_filter</a></code><br/><code><a href="./mod/mod_include.html">mod_include</a></code><br/></td><td valign="top"><strong>Related Directives</strong><br/><br/><a href="./mod/mod_mime.html#addinputfilter" class="directive"><code class="directive">AddInputFilter</code></a><br/><a href="./mod/mod_mime.html#addoutputfilter" class="directive"><code class="directive">AddOutputFilter</code></a><br/><a href="./mod/mod_ext_filter.html#extfilterdefine" class="directive"><code class="directive">ExtFilterDefine</code></a><br/><a href="./mod/mod_ext_filter.html#extfilteroptions" class="directive"><code class="directive">ExtFilterOptions</code></a><br/><a href="./mod/core.html.html#setinputfilter" class="directive"><code class="directive">SetInputFilter</code></a><br/><a href="./mod/core.html.html#setoutputfilter" class="directive"><code class="directive">SetOutputFilter</code></a><br/></td></tr></table>
    
    <p>A <em>filter</em> is a process that is applied to data that
    is sent or received by the server. Data sent by clients to the
    server is processed by <em>input filters</em> while data sent
    by the server to the client is processed by <em>output
    filters</em>. Multiple filters can be applied to the data, and
    the order of the filters can be explicitly specified.</p>

    <p>Filters are used internally by Apache to perform functions such
    as chunking and byte-range request handling. In addition, modules
    can provide filters that are selectable using run-time
    configuration directives. The set of filters that apply to data
    can be manipulated with the <a href="./mod/core.html.html#setinputfilter" class="directive"><code class="directive">SetInputFilter</code></a>, <a href="./mod/core.html.html#setoutputfilter" class="directive"><code class="directive">SetOutputFilter</code></a>, <a href="./mod/mod_mime.html#addinputfilter" class="directive"><code class="directive">AddInputFilter</code></a>, and <a href="./mod/mod_mime.html#addoutputfilter" class="directive"><code class="directive">AddOutputFilter</code></a> directives.</p>

    <p>The following user-selectable filters are currently provided
    with the Apache HTTP Server distribution.</p>

    <dl>
      <dt>INCLUDES</dt>
      <dd>Server-Side Includes processing by <code><a href="./mod/mod_include.html">mod_include</a></code></dd>
      <dt>DEFLATE</dt>
      <dd>Compress output before sending it to the client using <code><a href="./mod/mod_include.html">mod_include</a></code></dd>
    </dl>

    <p>In addition, the module <code><a href="./mod/mod_ext_filter.html">mod_ext_filter</a></code> allows
    for external programs to be defined as filters.</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>