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23 <manualpage metafile="new_features_2_4.xml.meta">
25 <title>Overview of new features in Apache 2.4</title>
28 <p>This document describes some of the major changes between the
29 2.2 and 2.4 versions of the Apache HTTP Server. For new features since
30 version 2.0, see the <a href="new_features_2_2.html">2.2 new features</a>
35 <title>Core Enhancements</title>
37 <dt>KeepAliveTimeout in milliseconds</dt>
39 <dd>It is now possible to specify <directive module="core"
40 >KeepAliveTimeout</directive> in milliseconds.
44 <dd>Cleanroom MPM implementation with advanced thread pool management</dd>
46 <dt>Loadable MPMs</dt>
47 <dd>Multiple MPMs can now be built as loadable modules at compile time.
48 The MPM of choice can be configured at run time.</dd>
54 <title>Module Enhancements</title>
56 <dt><module>mod_ssl</module></dt>
58 <dd><module>mod_ssl</module> can now be configured to use an
59 OCSP server to check the validation status of a client
60 certificate. The default responder is configurable, along with
61 the decision on whether to prefer the responder designated in
62 the client certificate itself.</dd>
64 <dd><module>mod_ssl</module> now also supports OCSP stapling, where the
65 server pro-actively obtains an OCSP verification of its certificate and
66 transmits that to the client during the handshake. </dd>
68 <dd><module>mod_ssl</module> can now be configured to share SSL Session
69 data between servers through memcached</dd>
71 <dt><module>mod_lua</module></dt>
73 <dd>Embeds the <a href="http://www.lua.org/">Lua</a> language into httpd,
74 for configuration and small business logic functions.</dd>
76 <dt><module>mod_proxy_fcgi</module></dt>
78 <dd>FastCGI Protocol backend for <module>mod_proxy</module></dd>
82 <section id="programs">
83 <title>Program Enhancements</title>
86 <dd>FastCGI deamon starter utility</dd>
90 <section id="developer">
91 <title>Module Developer Changes</title>
93 <dt>Check Configuration Hook Added</dt>
95 <dd>A new hook, <code>check_config</code>, has been added which runs
96 between the <code>pre_config</code> and <code>open_logs</code>
97 hooks. It also runs before the <code>test_config</code> hook
98 when the <code>-t</code> option is passed to
99 <program>httpd</program>. The <code>check_config</code> hook
100 allows modules to review interdependent configuration directive
101 values and adjust them while messages can still be logged to the
102 console. The user can thus be alerted to misconfiguration problems
103 before the core <code>open_logs</code> hook function redirects
104 console output to the error log.</dd>
106 <dt>Expression Parser Added</dt>
108 <dd>We now have a general-purpose expression parser, whose API is
109 exposed in <var>ap_expr.h</var>. This is adapted from the
110 expression parser previously implemented in
111 <module>mod_include</module>.</dd>
113 <dt>Authorization Logic Containers</dt>
115 <dd>Advanced authorization logic may now be specified using the
116 <directive module="mod_authz_core">Require</directive> directive
117 and the related container directives, such as
118 <directive module="mod_authz_core"
119 type="section">RequireAll</directive>, all
120 provided by the <module>mod_authz_core</module> module.</dd>
122 <dt>Small-Object Caching Interface</dt>
124 <dd>The <var>ap_socache.h</var> header exposes a provider-based
125 interface for caching small data objects, based on the previous
126 implementation of the <module>mod_ssl</module> session cache.
127 Providers using a shared-memory cyclic buffer, disk-based dbm
128 files, and a memcache distributed cache are currently