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4 <!-- $LastChangedRevision$ -->
7 Copyright 2002-2005 The Apache Software Foundation or its licensors, as
10 Licensed under the Apache License, Version 2.0 (the "License");
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23 <manualpage metafile="filter.xml.meta">
25 <title>Filters</title>
28 <p>This document describes the use of filters in Apache.</p>
31 <section id="filters">
32 <title>Filters</title>
35 <module>mod_deflate</module>
36 <module>mod_ext_filter</module>
37 <module>mod_include</module>
40 <directive module="mod_mime">AddInputFilter</directive>
41 <directive module="mod_mime">AddOutputFilter</directive>
42 <directive module="mod_mime">RemoveInputFilter</directive>
43 <directive module="mod_mime">RemoveOutputFilter</directive>
44 <directive module="mod_ext_filter">ExtFilterDefine</directive>
45 <directive module="mod_ext_filter">ExtFilterOptions</directive>
46 <directive module="core">SetInputFilter</directive>
47 <directive module="core">SetOutputFilter</directive>
51 <p>A <em>filter</em> is a process that is applied to data that
52 is sent or received by the server. Data sent by clients to the
53 server is processed by <em>input filters</em> while data sent
54 by the server to the client is processed by <em>output
55 filters</em>. Multiple filters can be applied to the data, and
56 the order of the filters can be explicitly specified.</p>
58 <p>Filters are used internally by Apache to perform functions such
59 as chunking and byte-range request handling. In addition, modules
60 can provide filters that are selectable using run-time
61 configuration directives. The set of filters that apply to data
62 can be manipulated with the
63 <directive module="core">SetInputFilter</directive>,
64 <directive module="core">SetOutputFilter</directive>,
65 <directive module="mod_mime">AddInputFilter</directive>,
66 <directive module="mod_mime">AddOutputFilter</directive>,
67 <directive module="mod_mime">RemoveInputFilter</directive>, and
68 <directive module="mod_mime">RemoveOutputFilter</directive>
71 <p>The following user-selectable filters are currently provided
72 with the Apache HTTP Server distribution.</p>
76 <dd>Server-Side Includes processing by <module>mod_include</module></dd>
78 <dd>Compress output before sending it to the client using
79 <module>mod_deflate</module>
83 <p>In addition, the module <module>mod_ext_filter</module> allows
84 for external programs to be defined as filters.</p>