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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. The new <module>mod_authn_alias</module> module
41 can greatly simplify certain authentication configurations.
42 See <a href="#module">module name changes</a>, and
43 <a href="#developer">the developer changes</a> for more
44 information about how these changes affects users and module
48 <dd><module>mod_cache</module>, <module>mod_disk_cache</module>, and
49 <module>mod_mem_cache</module> have undergone a lot of changes, and
50 are now considered production-quality. <program>htcacheclean</program>
51 has been introduced to clean up <module>mod_disk_cache</module>
54 <dt>Configuration</dt>
55 <dd>The default configuration layout has been simplified and
56 modularised. Configuration snippets which can be used to
57 enable commonly-used features are now bundled with Apache, and
58 can be easily added to the main server config.</dd>
60 <dt>Graceful stop</dt>
61 <dd>The <module>prefork</module>, <module>worker</module> and
62 <module>event</module> MPMs now allow <program>httpd</program>
63 to be shutdown gracefully via the
64 <a href="stopping.html#gracefulstop"><code>graceful-stop</code></a>
65 signal. The <directive
66 module="mpm_common">GracefulShutdownTimeout</directive> directive
67 has been added to specify an optional timeout, after which
68 <program>httpd</program> will terminate regardless of the status
69 of any requests being served.</dd>
72 <dd>The new <module>mod_proxy_balancer</module> module provides
73 load balancing services for <module>mod_proxy</module>.
74 The new <module>mod_proxy_ajp</module> module adds support for the
75 <code>Apache JServ Protocol version 1.3</code> used by
76 <a href="http://jakarta.apache.org/tomcat/">Apache Tomcat</a>.</dd>
78 <dt>Regular Expression Library Updated</dt>
79 <dd>Version 5.0 of the
80 <a href="http://www.pcre.org/">Perl Compatible Regular Expression
81 Library</a> (PCRE) is now included. <program>httpd</program> can be
82 configured to use a system installation of PCRE by passing the
83 <code>--with-pcre</code> flag to configure.</dd>
85 <dt>Smart Filtering</dt>
86 <dd><module>mod_filter</module> introduces dynamic configuration
87 to the output filter chain. It enables filters to be conditionally
88 inserted, based on any Request or Response header or environment
89 variable, and dispenses with the more problematic dependencies and
90 ordering problems in the 2.0 architecture.</dd>
92 <dt>Large File Support</dt>
94 <dd>httpd is now built with support for files larger than 2GB on
95 modern 32-bit Unix systems. Support for handling >2GB request
96 bodies has also been added.</dd>
99 <dd>The <module>event</module> MPM uses a seperate thread to handle
100 Keep Alive requests and accepting connections. Keep Alive requests
101 have traditionally required httpd to dedicate a worker to handle it.
102 This dedicated worker could not be used again until the Keep Alive
103 timeout was reached.</dd>
105 <dt>SQL Database Support</dt>
106 <dd><module>mod_dbd</module>, together with the apr_dbd framework,
107 brings direct SQL support to modules that need it. Supports
108 connection pooling in threaded MPMs.</dd>
113 <section id="module">
114 <title>Module Enhancements</title>
117 <dd>Modules in the aaa directory have been renamed and offer
118 better support for digest authentication. For example, mod_auth
119 is now split into <module>mod_auth_basic</module> and
120 <module>mod_auth_file</module>; mod_auth_dbm is now called
121 <module>mod_authn_dbm</module>; mod_access has been renamed
122 <module>mod_authz_host</module>. There is also a new
123 <module>mod_authn_alias</module> module for simplifying
124 certain authentication configurations.
127 <dt><module>mod_authnz_ldap</module></dt>
128 <dd>This module is a port of the 2.0
129 <code>mod_auth_ldap</code> module to the 2.2 <code>Authn/Authz</code>
130 framework. New features include using LDAP attribute values and
131 complicated search filters in the
132 <directive module="core">Require</directive> directive.</dd>
134 <dt><module>mod_info</module></dt>
135 <dd>Added a new <code>?config</code> argument which will show
136 the configuration directives as parsed by Apache, including
137 their file name and line number. The module also
138 shows the order of all request hooks and additional
139 build information, similar to <code>httpd -V</code>.</dd>
141 <dt><module>mod_ssl</module></dt>
142 <!-- Need Info on SSLEngine Support? -->
143 <dd>Added a support for
144 <a href="http://www.ietf.org/rfc/rfc2817.txt">RFC 2817</a>, which
145 allows connections to upgrade from clear text to TLS encryption.</dd>
147 <dt><module>mod_imagemap</module></dt>
148 <dd>mod_imap has been renamed to <module>mod_imagemap</module> to avoid
154 <section id="programs">
155 <title>Program Enhancements</title>
157 <dt><program>httpd</program></dt>
158 <dd>A new command line option <code>-M</code> has been added that
159 lists all modules that are loaded based on the current
160 configuration. Unlike the <code>-l</code> option, this list
161 includes DSOs loaded via <module>mod_so</module>.</dd>
165 <section id="developer">
166 <title>Module Developer Changes</title>
168 <dt><glossary>APR</glossary> 1.0 API</dt>
170 <dd>Apache 2.2 uses the APR 1.0 API. All deprecated functions and
171 symbols have been removed from <code>APR</code> and
172 <code>APR-Util</code>. For details, see the
173 <a href="http://apr.apache.org/">APR Website</a>.</dd>
176 <dd>The bundled authentication and authorization modules have
177 been renamed along the following lines:
179 <li>mod_auth_* -> Modules that implement an HTTP authentication mechanism</li>
180 <li>mod_authn_* -> Modules that provide a backend authentication provider</li>
181 <li>mod_authz_* -> Modules that implement authorization (or access)</li>
182 <li>mod_authnz_*-> Module that implements both authentication & authorization</li>
184 There is a new authentication backend provider
185 scheme which greatly eases the construction of new authentication
188 <dt>Connection Error Logging</dt>
190 <dd>A new function, <code>ap_log_cerror</code> has been added to log
191 errors that occure with the client's connection. When logged,
192 the message includes the client IP address.</dd>
194 <dt>Test Configuration Hook Added</dt>
196 <dd>A new hook, <code>test_config</code> has been added to aid
197 modules that want to execute special code only when the user passes
198 <code>-t</code> to <program>httpd</program>.</dd>
200 <dt>Set Threaded MPM's Stacksize</dt>
202 <dd>A new directive, <code>ThreadStackSize</code> has been added to
203 set the stack size on all threaded MPMs. This is required
204 for some third-party modules on platforms with small default
205 thread stack size.</dd>
207 <dt>Protocol handling for output filters</dt>
209 <dd>In the past, every filter has been responsible for ensuring
210 that it generates the correct response headers where it affects
211 them. Filters can now delegate common protocol management to
212 <module>mod_filter</module>, using the
213 <code>ap_register_output_filter_protocol</code> or
214 <code>ap_filter_protocol</code> calls.</dd>
216 <dt>Monitor hook added</dt>
217 <dd>Monitor hook enables modules to run regular/scheduled jobs
218 in the parent (root) process.</dd>
220 <dt>Regular expression API changes</dt>
222 <dd>The <code>pcreposix.h</code> header is no longer available;
223 it is replaced by the new <code>ap_regex.h</code> header. The
224 POSIX.2 <code>regex.h</code> implementation exposed by the old
225 header is now available under the <code>ap_</code> namespace
226 from <code>ap_regex.h</code>. Calls to <code>regcomp</code>,
227 <code>regexec</code> and so on can be replaced by calls to
228 <code>ap_regcomp</code>, <code>ap_regcomp</code>.</dd>
230 <dt>DBD Framework (SQL Database API)</dt>
232 <dd><p>With Apache 1.x and 2.0, modules requiring an SQL backend
233 had to take responsibility for managing it themselves. Apart
234 from reinventing the wheel, this can be very inefficient, for
235 example when several modules each maintain their own connections.</p>
236 <p>Apache 2.1 and up provides the <code>ap_dbd</code> API for
237 managing database connections (including optimised strategies
238 for threaded and unthreaded MPMs), while APR 1.2 and up provides
239 the <code>apr_dbd</code> API for interacting with the database.</p>
240 <p>New modules SHOULD now use these APIs for all SQL database
241 operations. Existing applications SHOULD be upgraded to use it
242 where feasible, either transparently or as a recommended option
243 to their users.</p></dd>