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23 <manualpage metafile="new_features_2_4.xml.meta">
25 <title>Overview of new features in Apache HTTP Server 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>
50 <dt>Per-module and per-directory LogLevel configuration</dt>
51 <dd>The <directive module="core">LogLevel</directive> can now be
52 configured per module and per directory. New levels <code>trace1</code>
53 to <code>trace8</code> have been added above the <code>debug</code> log
59 <title>Module Enhancements</title>
61 <dt><module>mod_ssl</module></dt>
63 <dd><module>mod_ssl</module> can now be configured to use an
64 OCSP server to check the validation status of a client
65 certificate. The default responder is configurable, along with
66 the decision on whether to prefer the responder designated in
67 the client certificate itself.</dd>
69 <dd><module>mod_ssl</module> now also supports OCSP stapling, where the
70 server pro-actively obtains an OCSP verification of its certificate and
71 transmits that to the client during the handshake. </dd>
73 <dd><module>mod_ssl</module> can now be configured to share SSL Session
74 data between servers through memcached</dd>
76 <dt><module>mod_lua</module></dt>
78 <dd>Embeds the <a href="http://www.lua.org/">Lua</a> language into httpd,
79 for configuration and small business logic functions.</dd>
81 <dt><module>mod_proxy_fcgi</module></dt>
83 <dd>FastCGI Protocol backend for <module>mod_proxy</module></dd>
87 <section id="programs">
88 <title>Program Enhancements</title>
91 <dd>FastCGI deamon starter utility</dd>
95 <section id="developer">
96 <title>Module Developer Changes</title>
98 <dt>Check Configuration Hook Added</dt>
100 <dd>A new hook, <code>check_config</code>, has been added which runs
101 between the <code>pre_config</code> and <code>open_logs</code>
102 hooks. It also runs before the <code>test_config</code> hook
103 when the <code>-t</code> option is passed to
104 <program>httpd</program>. The <code>check_config</code> hook
105 allows modules to review interdependent configuration directive
106 values and adjust them while messages can still be logged to the
107 console. The user can thus be alerted to misconfiguration problems
108 before the core <code>open_logs</code> hook function redirects
109 console output to the error log.</dd>
111 <dt>Expression Parser Added</dt>
113 <dd>We now have a general-purpose expression parser, whose API is
114 exposed in <var>ap_expr.h</var>. This is adapted from the
115 expression parser previously implemented in
116 <module>mod_include</module>.</dd>
118 <dt>Authorization Logic Containers</dt>
120 <dd>Advanced authorization logic may now be specified using the
121 <directive module="mod_authz_core">Require</directive> directive
122 and the related container directives, such as
123 <directive module="mod_authz_core"
124 type="section">RequireAll</directive>, all
125 provided by the <module>mod_authz_core</module> module.</dd>
127 <dt>Small-Object Caching Interface</dt>
129 <dd>The <var>ap_socache.h</var> header exposes a provider-based
130 interface for caching small data objects, based on the previous
131 implementation of the <module>mod_ssl</module> session cache.
132 Providers using a shared-memory cyclic buffer, disk-based dbm
133 files, and a memcache distributed cache are currently