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267 lines
12 KiB
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267 lines
12 KiB
XML
<?xml version='1.0' encoding='UTF-8' ?>
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<!DOCTYPE manualpage SYSTEM "./style/manualpage.dtd">
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<?xml-stylesheet type="text/xsl" href="./style/manual.en.xsl"?>
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<!-- $LastChangedRevision$ -->
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<!--
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Licensed to the Apache Software Foundation (ASF) under one or more
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contributor license agreements. See the NOTICE file distributed with
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this work for additional information regarding copyright ownership.
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The ASF licenses this file to You under the Apache License, Version 2.0
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(the "License"); you may not use this file except in compliance with
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the License. You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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-->
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<manualpage metafile="new_features_2_2.xml.meta">
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<title>Overview of new features in Apache HTTP Server 2.2</title>
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<summary>
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<p>This document describes some of the major changes between the
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2.0 and 2.2 versions of the Apache HTTP Server. For new features since
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version 1.3, see the <a href="new_features_2_0.html">2.0 new features</a>
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document.</p>
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</summary>
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<section id="core">
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<title>Core Enhancements</title>
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<dl>
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<dt>Authn/Authz</dt>
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<dd>The bundled authentication and authorization modules have
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been refactored. The new mod_authn_alias(already removed from 2.3/2.4)
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module can greatly simplify certain authentication configurations.
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See <a href="#module">module name changes</a>, and
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<a href="#developer">the developer changes</a> for more
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information about how these changes affects users and module
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writers.</dd>
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<dt>Caching</dt>
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<dd><module>mod_cache</module>, <module>mod_cache_disk</module>, and
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mod_mem_cache(already removed from 2.3/2.4) have undergone a lot of changes, and
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are now considered production-quality. <program>htcacheclean</program>
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has been introduced to clean up <module>mod_cache_disk</module>
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setups.</dd>
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<dt>Configuration</dt>
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<dd>The default configuration layout has been simplified and
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modularised. Configuration snippets which can be used to
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enable commonly-used features are now bundled with Apache, and
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can be easily added to the main server config.</dd>
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<dt>Graceful stop</dt>
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<dd>The <module>prefork</module>, <module>worker</module> and
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<module>event</module> MPMs now allow <program>httpd</program>
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to be shutdown gracefully via the
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<a href="stopping.html#gracefulstop"><code>graceful-stop</code></a>
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signal. The <directive
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module="mpm_common">GracefulShutdownTimeout</directive> directive
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has been added to specify an optional timeout, after which
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<program>httpd</program> will terminate regardless of the status
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of any requests being served.</dd>
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<dt>Proxying</dt>
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<dd>The new <module>mod_proxy_balancer</module> module provides
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load balancing services for <module>mod_proxy</module>.
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The new <module>mod_proxy_ajp</module> module adds support for the
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<code>Apache JServ Protocol version 1.3</code> used by
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<a href="http://tomcat.apache.org/">Apache Tomcat</a>.</dd>
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<dt>Regular Expression Library Updated</dt>
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<dd>Version 5.0 of the
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<a href="http://www.pcre.org/">Perl Compatible Regular Expression
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Library</a> (PCRE) is now included. <program>httpd</program> can be
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configured to use a system installation of PCRE by passing the
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<code>--with-pcre</code> flag to configure.</dd>
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<dt>Smart Filtering</dt>
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<dd><module>mod_filter</module> introduces dynamic configuration
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to the output filter chain. It enables filters to be conditionally
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inserted, based on any Request or Response header or environment
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variable, and dispenses with the more problematic dependencies and
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ordering problems in the 2.0 architecture.</dd>
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<dt>Large File Support</dt>
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<dd><program>httpd</program> is now built with support for files larger
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than 2GB on modern 32-bit Unix systems. Support for handling
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>2GB request bodies has also been added.</dd>
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<dt>Event MPM</dt>
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<dd>The <module>event</module> MPM uses a separate thread to handle
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Keep Alive requests and accepting connections. Keep Alive requests
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have traditionally required httpd to dedicate a worker to handle it.
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This dedicated worker could not be used again until the Keep Alive
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timeout was reached.</dd>
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<dt>SQL Database Support</dt>
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<dd><module>mod_dbd</module>, together with the <code>apr_dbd</code>
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framework, brings direct SQL support to modules that need it.
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Supports connection pooling in threaded MPMs.</dd>
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</dl>
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</section>
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<section id="module">
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<title>Module Enhancements</title>
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<dl>
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<dt>Authn/Authz</dt>
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<dd>Modules in the aaa directory have been renamed and offer
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better support for digest authentication. For example,
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<code>mod_auth</code> is now split into
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<module>mod_auth_basic</module> and
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<module>mod_authn_file</module>; <code>mod_auth_dbm</code> is now
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called <module>mod_authn_dbm</module>; <code>mod_access</code> has
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been renamed <module>mod_authz_host</module>. There is also a new
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mod_authn_alias(already removed from 2.3/2.4) module for simplifying
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certain authentication configurations.
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</dd>
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<dt><module>mod_authnz_ldap</module></dt>
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<dd>This module is a port of the 2.0
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<code>mod_auth_ldap</code> module to the 2.2 <code>Authn/Authz</code>
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framework. New features include using LDAP attribute values and
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complicated search filters in the
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<directive module="mod_authz_core">Require</directive> directive.</dd>
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<dt><module>mod_authz_owner</module></dt>
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<dd>A new module that authorizes access to files based
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on the owner of the file on the file system</dd>
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<dt><module>mod_version</module></dt>
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<dd>A new module that allows configuration blocks to be enabled based on the
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version number of the running server.</dd>
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<dt><module>mod_info</module></dt>
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<dd>Added a new <code>?config</code> argument which will show
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the configuration directives as parsed by Apache, including
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their file name and line number. The module also
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shows the order of all request hooks and additional
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build information, similar to <code>httpd -V</code>.</dd>
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<dt><module>mod_ssl</module></dt>
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<!-- Need Info on SSLEngine Support? -->
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<dd>Added a support for
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<a href="http://www.ietf.org/rfc/rfc2817.txt">RFC 2817</a>, which
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allows connections to upgrade from clear text to TLS encryption.</dd>
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<dt><module>mod_imagemap</module></dt>
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<dd><code>mod_imap</code> has been renamed to
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<module>mod_imagemap</module> to avoid user confusion.</dd>
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</dl>
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</section>
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<section id="programs">
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<title>Program Enhancements</title>
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<dl>
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<dt><program>httpd</program></dt>
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<dd>A new command line option <code>-M</code> has been added that
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lists all modules that are loaded based on the current
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configuration. Unlike the <code>-l</code> option, this list
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includes DSOs loaded via <module>mod_so</module>.</dd>
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<dt><program>httxt2dbm</program></dt>
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<dd>A new program used to generate dbm files from text input,
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for use in <directive module="mod_rewrite">RewriteMap</directive>
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with the <code>dbm</code> map type.</dd>
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</dl>
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</section>
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<section id="developer">
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<title>Module Developer Changes</title>
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<dl>
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<dt><glossary>APR</glossary> 1.0 API</dt>
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<dd>Apache 2.2 uses the APR 1.0 API. All deprecated functions and
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symbols have been removed from <code>APR</code> and
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<code>APR-Util</code>. For details, see the
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<a href="http://apr.apache.org/">APR Website</a>.</dd>
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<dt>Authn/Authz</dt>
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<dd>The bundled authentication and authorization modules have
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been renamed along the following lines:
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<ul>
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<li><code>mod_auth_*</code> -> Modules that implement an HTTP
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authentication mechanism</li>
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<li><code>mod_authn_*</code> -> Modules that provide a backend
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authentication provider</li>
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<li><code>mod_authz_*</code> -> Modules that implement
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authorization (or access)</li>
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<li><code>mod_authnz_*</code> -> Module that implements both
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authentication & authorization</li>
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</ul>
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There is a new authentication backend provider
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scheme which greatly eases the construction of new authentication
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backends.</dd>
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<dt>Connection Error Logging</dt>
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<dd>A new function, <code>ap_log_cerror</code> has been added to log
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errors that occur with the client's connection. When logged,
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the message includes the client IP address.</dd>
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<dt>Test Configuration Hook Added</dt>
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<dd>A new hook, <code>test_config</code> has been added to aid
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modules that want to execute special code only when the user passes
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<code>-t</code> to <program>httpd</program>.</dd>
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<dt>Set Threaded MPM's Stacksize</dt>
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<dd>A new directive, <directive module="mpm_common"
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>ThreadStackSize</directive> has been added to
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set the stack size on all threaded MPMs. This is required
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for some third-party modules on platforms with small default
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thread stack size.</dd>
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<dt>Protocol handling for output filters</dt>
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<dd>In the past, every filter has been responsible for ensuring
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that it generates the correct response headers where it affects
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them. Filters can now delegate common protocol management to
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<module>mod_filter</module>, using the
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<code>ap_register_output_filter_protocol</code> or
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<code>ap_filter_protocol</code> calls.</dd>
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<dt>Monitor hook added</dt>
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<dd>Monitor hook enables modules to run regular/scheduled jobs
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in the parent (root) process.</dd>
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<dt>Regular expression API changes</dt>
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<dd>The <code>pcreposix.h</code> header is no longer available;
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it is replaced by the new <code>ap_regex.h</code> header. The
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POSIX.2 <code>regex.h</code> implementation exposed by the old
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header is now available under the <code>ap_</code> namespace
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from <code>ap_regex.h</code>. Calls to <code>regcomp</code>,
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<code>regexec</code> and so on can be replaced by calls to
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<code>ap_regcomp</code>, <code>ap_regexec</code>.</dd>
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<dt>DBD Framework (SQL Database API)</dt>
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<dd><p>With Apache 1.x and 2.0, modules requiring an SQL backend
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had to take responsibility for managing it themselves. Apart
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from reinventing the wheel, this can be very inefficient, for
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example when several modules each maintain their own connections.</p>
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<p>Apache 2.1 and later provides the <code>ap_dbd</code> API for
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managing database connections (including optimised strategies
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for threaded and unthreaded MPMs), while APR 1.2 and later provides
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the <code>apr_dbd</code> API for interacting with the database.</p>
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<p>New modules SHOULD now use these APIs for all SQL database
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operations. Existing applications SHOULD be upgraded to use it
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where feasible, either transparently or as a recommended option
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to their users.</p></dd>
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</dl>
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</section>
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</manualpage>
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