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7 Copyright 2004-2005 The Apache Software Foundation or its licensors, as
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23 <manualpage metafile="new_features_2_2.xml.meta">
25 <title>Overview of new features in Apache 2.2</title>
28 <p>This document describes some of the major changes between the
29 2.0 and 2.2 versions of the Apache HTTP Server. For new features since
30 version 1.3, see the <a href="new_features_2_0.html">2.0 new features</a>
35 <title>Core Enhancements</title>
39 <dd>The bundled authentication and authorization modules have
40 been refactored. There is a new authentication backend provider
41 scheme which greatly eases the construction of new authentication
45 <dd><module>mod_cache</module>, <module>mod_disk_cache</module>, and
46 <module>mod_mem_cache</module> have undergone a lot of changes
47 are now considered production-quality. <program>htcacheclean</program>
48 has been introduced to cleanup <module>mod_disk_cache</module>
51 <dt>Graceful stop</dt>
52 <dd>The <module>prefork</module>, <module>worker</module> and
53 <module>event</module> MPMs now allow <program>httpd</program>
54 to be shutdown gracefully via the
55 <a href="stopping.html#gracefulstop"><code>graceful-stop</code></a>
56 signal. The <directive
57 module="mpm_common">GracefulShutdownTimeout</directive> directive
58 has been added to specify an optional timeout, after which
59 <program>httpd</program> will terminate regardless of the status
60 of any requests being served.</dd>
63 <dd>The new <module>mod_proxy_balancer</module> module provides
64 load balancing services for <module>mod_proxy</module>.
65 The new <module>mod_proxy_ajp</module> module adds support for the
66 <code>Apache JServ Protocol version 1.3</code> used by
67 <a href="http://jakarta.apache.org/tomcat/">Apache Tomcat</a>.</dd>
69 <dt>Regular Expression Library Updated</dt>
70 <dd>Version 5.0 of the
71 <a href="http://www.pcre.org/">Perl Compatible Regular Expression
72 Library</a> (PCRE) is now included. <program>httpd</program> can be
73 configured to use a system installation of PCRE by passing the
74 <code>--with-pcre</code> flag to configure.</dd>
76 <dt>Smart Filtering</dt>
77 <dd><module>mod_filter</module> introduces dynamic configuration
78 to the output filter chain. It enables filters to be conditionally
79 inserted, based on any Request or Response header or environment
80 variable, and dispenses with the more problematic dependencies and
81 ordering problems in the 2.0 architecture.</dd>
83 <dt>Large File Support</dt>
85 <dd>httpd is now built with support for files larger than 2Gb on
86 modern 32-bit Unix systems. Support for handling >2Gb request
87 bodies has also been added.</dd>
90 <dd>The <module>event</module> MPM uses a seperate thread to handle
91 Keep Alive requests and accepting connections. Keep Alive requests
92 have traditionally required httpd to dedicate a worker to handle it.
93 This dedicated worker could not be used again until the Keep Alive
94 timeout was reached.</dd>
96 <dt>SQL Database Support</dt>
97 <dd><module>mod_dbd</module>, together with the apr_dbd framework,
98 brings direct SQL support to modules that need it. Supports
99 connection pooling in threaded MPMs.</dd>
104 <section id="module">
105 <title>Module Enhancements</title>
107 <dt><module>mod_authnz_ldap</module></dt>
108 <dd>This module is a port of the 2.0
109 <code>mod_auth_ldap</code> module to the 2.2 <code>Authn/Authz</code>
110 framework. New features include using LDAP attribute values and
111 complicated search filters in the
112 <directive module="core">Require</directive> directive.</dd>
114 <dt><module>mod_info</module></dt>
115 <dd>Added a new <code>?config</code> argument which will show
116 the configuration directives as parsed by Apache, including
117 their file name and line number. The module also
118 shows the order of all request hooks and additional
119 build information, similar to <code>httpd -V</code>.</dd>
121 <dt><module>mod_ssl</module></dt>
122 <!-- Need Info on SSLEngine Support? -->
123 <dd>Added a support for
124 <a href="http://www.ietf.org/rfc/rfc2817.txt">RFC 2817</a>, which
125 allows connections to upgrade from clear text to TLS encryption.</dd>
129 <section id="programs">
130 <title>Program Enhancements</title>
132 <dt><program>httpd</program></dt>
133 <dd>A new command line option <code>-M</code> has been added that
134 lists all modules that are loaded based on the current
135 configuration. Unlike the <code>-l</code> option, this list
136 includes DSOs loaded via <module>mod_so</module>.</dd>
140 <section id="developer">
141 <title>Module Developer Changes</title>
143 <dt><glossary>APR</glossary> 1.0 API</dt>
145 <dd>Apache 2.2 uses the APR 1.0 API. All deprecated functions and
146 symbols have been removed from <code>APR</code> and
147 <code>APR-Util</code>. For details, see the
148 <a href="http://apr.apache.org/">APR Website</a>.</dd>
150 <dt>Connection Error Logging</dt>
152 <dd>A new function, <code>ap_log_cerror</code> has been added to log
153 errors that occure with the client's connection. When logged,
154 the message includes the client IP address.</dd>
156 <dt>Test Configuration Hook Added</dt>
158 <dd>A new hook, <code>test_config</code> has been added to aid
159 modules that want to execute special code only when the user passes
160 <code>-t</code> to <program>httpd</program>.</dd>
162 <dt>Set Threaded MPM's Stacksize</dt>
164 <dd>A new directive, <code>ThreadStackSize</code> has been added to
165 set the stack size on all threaded MPMs. This is required
166 for some third-party modules on platforms with small default
167 thread stack size.</dd>
169 <dt>Protocol handling for output filters</dt>
171 <dd>In the past, every filter has been responsible for ensuring
172 that it generates the correct response headers where it affects
173 them. Filters can now delegate common protocol management to
174 <module>mod_filter</module>, using the
175 <code>ap_register_output_filter_protocol</code> or
176 <code>ap_filter_protocol</code> calls.</dd>
178 <dt>Monitor hook added</dt>
179 <dd>Monitor hook enables modules to run regular/scheduled jobs
180 in the parent (root) process.</dd>
182 <dt>Regular expression API changes</dt>
184 <dd>The <code>pcreposix.h</code> header is no longer available;
185 it is replaced by the new <code>ap_regex.h</code> header. The
186 POSIX.2 <code>regex.h</code> implementation exposed by the old
187 header is now available under the <code>ap_</code> namespace
188 from <code>ap_regex.h</code>. Calls to <code>regcomp</code>,
189 <code>regexec</code> and so on can be replaced by calls to
190 <code>ap_regcomp</code>, <code>ap_regcomp</code>.</dd>
192 <dt>DBD Framework (SQL Database API)</dt>
194 <dd><p>With Apache 1.x and 2.0, modules requiring an SQL backend
195 had to take responsibility for managing it themselves. Apart
196 from reinventing the wheel, this can be very inefficient, for
197 example when several modules each maintain their own connections.</p>
198 <p>Apache 2.1 and up provides the <code>ap_dbd</code> API for
199 managing database connections (including optimised strategies
200 for threaded and unthreaded MPMs), while APR 1.2 and up provides
201 the <code>apr_dbd</code> API for interacting with the database.</p>
202 <p>New modules SHOULD now use these APIs for all SQL database
203 operations. Existing applications SHOULD be upgraded to use it
204 where feasible, either transparently or as a recommended option
205 to their users.</p></dd>