filter.html.en revision edac3c10bbcea19fdece3de8401666e4301d2a49
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN">
<HTML>
<HEAD>
<TITLE>Filters - Apache HTTPD</TITLE>
</HEAD>
<!-- Background white, links blue (unvisited), navy (visited), red (active) -->
<BODY
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#000080"
ALINK="#FF0000"
>
<!--#include virtual="header.html" -->
<H1 ALIGN="CENTER">Filters</H1>
<table border="1">
<tr><td valign="top">
<strong>Related Modules</strong><br><br>
<a href="mod/mod_ext_filter.html">mod_ext_filter</a><br>
<A HREF="mod/mod_include.html">mod_include</A><br>
</td>
<td valign="top">
<strong>Related Directives</strong><br><br>
<a href="mod/mod_mime.html#addoutputfilter">AddOutputFilter</a><br>
<a href="mod/mod_ext_filter.html#extfilterdefine">ExtFilterDefine</a></br>
<a href="mod/mod_ext_filter.html#extfilteroptions">ExtFilterOptions</a><br>
<a href="mod/core.html#setinputfilter">SetInputFilter</a><br>
<a href="mod/core.html#setoutputfilter">SetOutputFilter</a><br>
</td>
</tr></table>
<p>A <em>filter</em> is a process which 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 which are selectable using run-time configuration
directives. The set of filters which apply to data can be manipulated
with the <code>SetInputFilter</code> and <code>SetOutputFilter</code>
directives.</p>
<p>The only configurable filter currently included with the Apache
distribution is the <code>INCLUDES</code> filter which is provided by
<a href="mod/mod_include.html">mod_include</a> to process output for
Server Side Includes. There is also an experimental module called <a
href="mod/mod_ext_filter.html">mod_ext_filter</a> which allows for
external programs to be defined as filters.</p>
<!--#include virtual="footer.html" -->
</BODY>
</HTML>