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5 <manualpage metafile="filter.xml.meta">
10 <p>This document describes the use of filters in Apache.</p>
13 <section id="filters">
14 <title>Filters</title>
17 <module>mod_deflate</module>
18 <module>mod_ext_filter</module>
19 <module>mod_include</module>
22 <directive module="mod_mime">AddInputFilter</directive>
23 <directive module="mod_mime">AddOutputFilter</directive>
24 <directive module="mod_mime">RemoveInputFilter</directive>
25 <directive module="mod_mime">RemoveOutputFilter</directive>
26 <directive module="mod_ext_filter">ExtFilterDefine</directive>
27 <directive module="mod_ext_filter">ExtFilterOptions</directive>
28 <directive module="core">SetInputFilter</directive>
29 <directive module="core">SetOutputFilter</directive>
33 <p>A <em>filter</em> is a process that is applied to data that
34 is sent or received by the server. Data sent by clients to the
35 server is processed by <em>input filters</em> while data sent
36 by the server to the client is processed by <em>output
37 filters</em>. Multiple filters can be applied to the data, and
38 the order of the filters can be explicitly specified.</p>
40 <p>Filters are used internally by Apache to perform functions such
41 as chunking and byte-range request handling. In addition, modules
42 can provide filters that are selectable using run-time
43 configuration directives. The set of filters that apply to data
44 can be manipulated with the
45 <directive module="core">SetInputFilter</directive>,
46 <directive module="core">SetOutputFilter</directive>,
47 <directive module="mod_mime">AddInputFilter</directive>,
48 <directive module="mod_mime">AddOutputFilter</directive>,
49 <directive module="mod_mime">RemoveInputFilter</directive>, and
50 <directive module="mod_mime">RemoveOutputFilter</directive>
53 <p>The following user-selectable filters are currently provided
54 with the Apache HTTP Server distribution.</p>
58 <dd>Server-Side Includes processing by <module>mod_include</module></dd>
60 <dd>Compress output before sending it to the client using
61 <module>mod_deflate</module>
65 <p>In addition, the module <module>mod_ext_filter</module> allows
66 for external programs to be defined as filters.</p>