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 <p class="apache">Apache HTTP Server Version 2.5</p>
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   <p>This document describes some of the major changes between the
      2.0 and 2.2 versions of the Apache HTTP Server. For new features since
      version 1.3, see the <a href="new_features_2_0.html">2.0 new features</a>
      document.</p>
 </div>
 <div id="quickview"><ul id="toc"><li><img alt="" src="./images/down.gif" /> <a href="#core">Core Enhancements</a></li>
 <li><img alt="" src="./images/down.gif" /> <a href="#module">Module Enhancements</a></li>
 <li><img alt="" src="./images/down.gif" /> <a href="#programs">Program Enhancements</a></li>
 <li><img alt="" src="./images/down.gif" /> <a href="#developer">Module Developer Changes</a></li>
 </ul><h3>See also</h3><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
 <div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="core" id="core">Core Enhancements</a></h2>

     <dl>

       <dt>Authn/Authz</dt>
       <dd>The bundled authentication and authorization modules have
           been refactored.  The new mod_authn_alias(already removed from 2.3/2.4)
           module can greatly simplify certain authentication configurations.
           See <a href="#module">module name changes</a>, and
           <a href="#developer">the developer changes</a> for more
           information about how these changes affects users and module
           writers.</dd>

       <dt>Caching</dt>
       <dd><code class="module"><a href="./mod/mod_cache.html">mod_cache</a></code>, <code class="module"><a href="./mod/mod_cache_disk.html">mod_cache_disk</a></code>, and
           mod_mem_cache(already removed from 2.3/2.4) have undergone a lot of changes, and
           are now considered production-quality. <code class="program"><a href="./programs/htcacheclean.html">htcacheclean</a></code>
           has been introduced to clean up <code class="module"><a href="./mod/mod_cache_disk.html">mod_cache_disk</a></code>
           setups.</dd>

       <dt>Configuration</dt>
       <dd>The default configuration layout has been simplified and
           modularised. Configuration snippets which can be used to
           enable commonly-used features are now bundled with Apache, and
           can be easily added to the main server config.</dd>

       <dt>Graceful stop</dt>
       <dd>The <code class="module"><a href="./mod/prefork.html">prefork</a></code>, <code class="module"><a href="./mod/worker.html">worker</a></code> and
           <code class="module"><a href="./mod/event.html">event</a></code>  MPMs now allow <code class="program"><a href="./programs/httpd.html">httpd</a></code>
           to be shutdown gracefully via the
           <a href="stopping.html#gracefulstop"><code>graceful-stop</code></a>
           signal. The <code class="directive"><a href="./mod/mpm_common.html#gracefulshutdowntimeout">GracefulShutdownTimeout</a></code> directive
           has been added to specify an optional timeout, after which
           <code class="program"><a href="./programs/httpd.html">httpd</a></code> will terminate regardless of the status
           of any requests being served.</dd>

       <dt>Proxying</dt>
       <dd>The new <code class="module"><a href="./mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code> module provides
           load balancing services for <code class="module"><a href="./mod/mod_proxy.html">mod_proxy</a></code>.
           The new <code class="module"><a href="./mod/mod_proxy_ajp.html">mod_proxy_ajp</a></code> module adds support for the
           <code>Apache JServ Protocol version 1.3</code> used by
           <a href="http://tomcat.apache.org/">Apache Tomcat</a>.</dd>

       <dt>Regular Expression Library Updated</dt>
       <dd>Version 5.0 of the
           <a href="http://www.pcre.org/">Perl Compatible Regular Expression
           Library</a> (PCRE) is now included.  <code class="program"><a href="./programs/httpd.html">httpd</a></code> can be
           configured to use a system installation of PCRE by passing the
           <code>--with-pcre</code> flag to configure.</dd>

       <dt>Smart Filtering</dt>
       <dd><code class="module"><a href="./mod/mod_filter.html">mod_filter</a></code> introduces dynamic configuration
           to the output filter chain.  It enables filters to be conditionally
           inserted, based on any Request or Response header or environment
           variable, and dispenses with the more problematic dependencies and
           ordering problems in the 2.0 architecture.</dd>

       <dt>Large File Support</dt>
       <dd><code class="program"><a href="./programs/httpd.html">httpd</a></code> is now built with support for files larger
           than 2GB on modern 32-bit Unix systems.  Support for handling
           &gt;2GB request bodies has also been added.</dd>

       <dt>Event MPM</dt>
       <dd>The <code class="module"><a href="./mod/event.html">event</a></code> MPM uses a separate thread to handle
           Keep Alive requests and accepting connections.  Keep Alive requests
           have traditionally required httpd to dedicate a worker to handle it.
           This dedicated worker could not be used again until the Keep Alive
           timeout was reached.</dd>

       <dt>SQL Database Support</dt>
       <dd><code class="module"><a href="./mod/mod_dbd.html">mod_dbd</a></code>, together with the <code>apr_dbd</code>
           framework, brings direct SQL support to modules that need it.
           Supports connection pooling in threaded MPMs.</dd>

     </dl>
   </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="module" id="module">Module Enhancements</a></h2>

     <dl>
       <dt>Authn/Authz</dt>
       <dd>Modules in the aaa directory have been renamed and offer
           better support for digest authentication.  For example,
           <code>mod_auth</code> is now split into
           <code class="module"><a href="./mod/mod_auth_basic.html">mod_auth_basic</a></code> and
           <code class="module"><a href="./mod/mod_authn_file.html">mod_authn_file</a></code>; <code>mod_auth_dbm</code> is now
           called <code class="module"><a href="./mod/mod_authn_dbm.html">mod_authn_dbm</a></code>; <code>mod_access</code> has
           been renamed <code class="module"><a href="./mod/mod_authz_host.html">mod_authz_host</a></code>.  There is also a new
           mod_authn_alias(already removed from 2.3/2.4) module for simplifying
           certain authentication configurations.
       </dd>

       <dt><code class="module">mod_authnz_ldap</code></dt>
       <dd>This module is a port of the 2.0
           <code>mod_auth_ldap</code> module to the 2.2 <code>Authn/Authz</code>
           framework.  New features include using LDAP attribute values and
           complicated search filters in the
           <code class="directive"><a href="./mod/mod_authz_core.html#require">Require</a></code> directive.</dd>

       <dt><code class="module"><a href="./mod/mod_authz_owner.html">mod_authz_owner</a></code></dt>
       <dd>A new module that authorizes access to files based
           on the owner of the file on the file system</dd>

       <dt><code class="module"><a href="./mod/mod_version.html">mod_version</a></code></dt>
       <dd>A new module that allows configuration blocks to be enabled based on the
           version number of the running server.</dd>

       <dt><code class="module"><a href="./mod/mod_info.html">mod_info</a></code></dt>
       <dd>Added a new <code>?config</code> argument which will show
           the configuration directives as parsed by Apache, including
           their file name and line number.  The module also
           shows the order of all request hooks and additional
           build information, similar to <code>httpd -V</code>.</dd>

       <dt><code class="module"><a href="./mod/mod_ssl.html">mod_ssl</a></code></dt>

       <dd>Added a support for
          <a href="http://www.ietf.org/rfc/rfc2817.txt">RFC 2817</a>, which
          allows connections to upgrade from clear text to TLS encryption.</dd>

       <dt><code class="module"><a href="./mod/mod_imagemap.html">mod_imagemap</a></code></dt>
       <dd><code>mod_imap</code> has been renamed to
           <code class="module"><a href="./mod/mod_imagemap.html">mod_imagemap</a></code> to avoid user confusion.</dd>
     </dl>

   </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="programs" id="programs">Program Enhancements</a></h2>

     <dl>
       <dt><code class="program"><a href="./programs/httpd.html">httpd</a></code></dt>
       <dd>A new command line option <code>-M</code> has been added that
       lists all modules that are loaded based on the current
       configuration. Unlike the <code>-l</code> option, this list
       includes DSOs loaded via <code class="module"><a href="./mod/mod_so.html">mod_so</a></code>.</dd>

       <dt><code class="program"><a href="./programs/httxt2dbm.html">httxt2dbm</a></code></dt>
       <dd>A new program used to generate dbm files from text input,
           for use in <code class="directive"><a href="./mod/mod_rewrite.html#rewritemap">RewriteMap</a></code>
           with the <code>dbm</code> map type.</dd>
     </dl>
   </div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
 <div class="section">
 <h2><a name="developer" id="developer">Module Developer Changes</a></h2>

     <dl>
       <dt><a class="glossarylink" href="./glossary.html#apr" title="see glossary">APR</a> 1.0 API</dt>

       <dd>Apache 2.2 uses the APR 1.0 API.  All deprecated functions and
           symbols have been removed from <code>APR</code> and
           <code>APR-Util</code>. For details, see the
           <a href="http://apr.apache.org/">APR Website</a>.</dd>

       <dt>Authn/Authz</dt>
       <dd>The bundled authentication and authorization modules have
           been renamed along the following lines:
           <ul>
           <li><code>mod_auth_*</code>  -&gt; Modules that implement an HTTP
           authentication mechanism</li>
           <li><code>mod_authn_*</code> -&gt; Modules that provide a backend
           authentication provider</li>
           <li><code>mod_authz_*</code> -&gt; Modules that implement
           authorization (or access)</li>
           <li><code>mod_authnz_*</code> -&gt; Module that implements both
           authentication &amp; authorization</li>
           </ul>
           There is a new authentication backend provider
           scheme which greatly eases the construction of new authentication
           backends.</dd>

       <dt>Connection Error Logging</dt>

       <dd>A new function, <code>ap_log_cerror</code> has been added to log
           errors that occur with the client's connection.  When logged,
           the message includes the client IP address.</dd>

       <dt>Test Configuration Hook Added</dt>

       <dd>A new hook, <code>test_config</code> has been added to aid
           modules that want to execute special code only when the user passes
           <code>-t</code> to <code class="program"><a href="./programs/httpd.html">httpd</a></code>.</dd>

       <dt>Set Threaded MPM's Stacksize</dt>

       <dd>A new directive, <code class="directive"><a href="./mod/mpm_common.html#threadstacksize">ThreadStackSize</a></code> has been added to
           set the stack size on all threaded MPMs.  This is required
           for some third-party modules on platforms with small default
           thread stack size.</dd>

       <dt>Protocol handling for output filters</dt>

       <dd>In the past, every filter has been responsible for ensuring
           that it generates the correct response headers where it affects
           them.  Filters can now delegate common protocol management to
           <code class="module"><a href="./mod/mod_filter.html">mod_filter</a></code>, using the
           <code>ap_register_output_filter_protocol</code> or
           <code>ap_filter_protocol</code> calls.</dd>

       <dt>Monitor hook added</dt>
       <dd>Monitor hook enables modules to run regular/scheduled jobs
           in the parent (root) process.</dd>

       <dt>Regular expression API changes</dt>

       <dd>The <code>pcreposix.h</code> header is no longer available;
       it is replaced by the new <code>ap_regex.h</code> header.  The
       POSIX.2 <code>regex.h</code> implementation exposed by the old
       header is now available under the <code>ap_</code> namespace
       from <code>ap_regex.h</code>.  Calls to <code>regcomp</code>,
       <code>regexec</code> and so on can be replaced by calls to
       <code>ap_regcomp</code>, <code>ap_regexec</code>.</dd>

       <dt>DBD Framework (SQL Database API)</dt>

       <dd><p>With Apache 1.x and 2.0, modules requiring an SQL backend
       had to take responsibility for managing it themselves.  Apart
       from reinventing the wheel, this can be very inefficient, for
       example when several modules each maintain their own connections.</p>

       <p>Apache 2.1 and later provides the <code>ap_dbd</code> API for
       managing database connections (including optimised strategies
       for threaded and unthreaded MPMs), while APR 1.2 and later provides
       the <code>apr_dbd</code> API for interacting with the database.</p>

       <p>New modules SHOULD now use these APIs for all SQL database
       operations.  Existing applications SHOULD be upgraded to use it
       where feasible, either transparently or as a recommended option
       to their users.</p></dd>
     </dl>
   </div></div>
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	<p class="apache">Apache HTTP Server Version 2.5</p>
	<img alt="" src="./images/feather.png" /></div>
	<div class="up"><a href="./"><img title="<-" alt="<-" src="./images/left.gif" /></a></div>
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	<a href="http://www.apache.org/">Apache</a> > <a href="http://httpd.apache.org/">HTTP Server</a> > <a href="http://httpd.apache.org/docs/">Documentation</a> > <a href="./">Version 2.5</a></div><div id="page-content"><div id="preamble"><h1>Overview of new features in Apache HTTP Server 2.2</h1>
	<div class="toplang">
	<p><span>Available Languages: </span><a href="./en/new_features_2_2.html" title="English"> en </a> \|
	<a href="./es/new_features_2_2.html" hreflang="es" rel="alternate" title="Español"> es </a> \|
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	</div>

	<p>This document describes some of the major changes between the
	2.0 and 2.2 versions of the Apache HTTP Server. For new features since
	version 1.3, see the <a href="new_features_2_0.html">2.0 new features</a>
	document.</p>
	</div>
	<div id="quickview"><ul id="toc"><li><img alt="" src="./images/down.gif" /> <a href="#core">Core Enhancements</a></li>
	<li><img alt="" src="./images/down.gif" /> <a href="#module">Module Enhancements</a></li>
	<li><img alt="" src="./images/down.gif" /> <a href="#programs">Program Enhancements</a></li>
	<li><img alt="" src="./images/down.gif" /> <a href="#developer">Module Developer Changes</a></li>
	</ul><h3>See also</h3><ul class="seealso"><li><a href="#comments_section">Comments</a></li></ul></div>
	<div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="core" id="core">Core Enhancements</a></h2>

	<dl>

	<dt>Authn/Authz</dt>
	<dd>The bundled authentication and authorization modules have
	been refactored. The new mod_authn_alias(already removed from 2.3/2.4)
	module can greatly simplify certain authentication configurations.
	See <a href="#module">module name changes</a>, and
	<a href="#developer">the developer changes</a> for more
	information about how these changes affects users and module
	writers.</dd>

	<dt>Caching</dt>
	<dd><code class="module"><a href="./mod/mod_cache.html">mod_cache</a></code>, <code class="module"><a href="./mod/mod_cache_disk.html">mod_cache_disk</a></code>, and
	mod_mem_cache(already removed from 2.3/2.4) have undergone a lot of changes, and
	are now considered production-quality. <code class="program"><a href="./programs/htcacheclean.html">htcacheclean</a></code>
	has been introduced to clean up <code class="module"><a href="./mod/mod_cache_disk.html">mod_cache_disk</a></code>
	setups.</dd>

	<dt>Configuration</dt>
	<dd>The default configuration layout has been simplified and
	modularised. Configuration snippets which can be used to
	enable commonly-used features are now bundled with Apache, and
	can be easily added to the main server config.</dd>

	<dt>Graceful stop</dt>
	<dd>The <code class="module"><a href="./mod/prefork.html">prefork</a></code>, <code class="module"><a href="./mod/worker.html">worker</a></code> and
	<code class="module"><a href="./mod/event.html">event</a></code> MPMs now allow <code class="program"><a href="./programs/httpd.html">httpd</a></code>
	to be shutdown gracefully via the
	<a href="stopping.html#gracefulstop"><code>graceful-stop</code></a>
	signal. The <code class="directive"><a href="./mod/mpm_common.html#gracefulshutdowntimeout">GracefulShutdownTimeout</a></code> directive
	has been added to specify an optional timeout, after which
	<code class="program"><a href="./programs/httpd.html">httpd</a></code> will terminate regardless of the status
	of any requests being served.</dd>

	<dt>Proxying</dt>
	<dd>The new <code class="module"><a href="./mod/mod_proxy_balancer.html">mod_proxy_balancer</a></code> module provides
	load balancing services for <code class="module"><a href="./mod/mod_proxy.html">mod_proxy</a></code>.
	The new <code class="module"><a href="./mod/mod_proxy_ajp.html">mod_proxy_ajp</a></code> module adds support for the
	<code>Apache JServ Protocol version 1.3</code> used by
	<a href="http://tomcat.apache.org/">Apache Tomcat</a>.</dd>

	<dt>Regular Expression Library Updated</dt>
	<dd>Version 5.0 of the
	<a href="http://www.pcre.org/">Perl Compatible Regular Expression
	Library</a> (PCRE) is now included. <code class="program"><a href="./programs/httpd.html">httpd</a></code> can be
	configured to use a system installation of PCRE by passing the
	<code>--with-pcre</code> flag to configure.</dd>

	<dt>Smart Filtering</dt>
	<dd><code class="module"><a href="./mod/mod_filter.html">mod_filter</a></code> introduces dynamic configuration
	to the output filter chain. It enables filters to be conditionally
	inserted, based on any Request or Response header or environment
	variable, and dispenses with the more problematic dependencies and
	ordering problems in the 2.0 architecture.</dd>

	<dt>Large File Support</dt>
	<dd><code class="program"><a href="./programs/httpd.html">httpd</a></code> is now built with support for files larger
	than 2GB on modern 32-bit Unix systems. Support for handling
	>2GB request bodies has also been added.</dd>

	<dt>Event MPM</dt>
	<dd>The <code class="module"><a href="./mod/event.html">event</a></code> MPM uses a separate thread to handle
	Keep Alive requests and accepting connections. Keep Alive requests
	have traditionally required httpd to dedicate a worker to handle it.
	This dedicated worker could not be used again until the Keep Alive
	timeout was reached.</dd>

	<dt>SQL Database Support</dt>
	<dd><code class="module"><a href="./mod/mod_dbd.html">mod_dbd</a></code>, together with the <code>apr_dbd</code>
	framework, brings direct SQL support to modules that need it.
	Supports connection pooling in threaded MPMs.</dd>

	</dl>
	</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="module" id="module">Module Enhancements</a></h2>

	<dl>
	<dt>Authn/Authz</dt>
	<dd>Modules in the aaa directory have been renamed and offer
	better support for digest authentication. For example,
	<code>mod_auth</code> is now split into
	<code class="module"><a href="./mod/mod_auth_basic.html">mod_auth_basic</a></code> and
	<code class="module"><a href="./mod/mod_authn_file.html">mod_authn_file</a></code>; <code>mod_auth_dbm</code> is now
	called <code class="module"><a href="./mod/mod_authn_dbm.html">mod_authn_dbm</a></code>; <code>mod_access</code> has
	been renamed <code class="module"><a href="./mod/mod_authz_host.html">mod_authz_host</a></code>. There is also a new
	mod_authn_alias(already removed from 2.3/2.4) module for simplifying
	certain authentication configurations.
	</dd>

	<dt><code class="module">mod_authnz_ldap</code></dt>
	<dd>This module is a port of the 2.0
	<code>mod_auth_ldap</code> module to the 2.2 <code>Authn/Authz</code>
	framework. New features include using LDAP attribute values and
	complicated search filters in the
	<code class="directive"><a href="./mod/mod_authz_core.html#require">Require</a></code> directive.</dd>

	<dt><code class="module"><a href="./mod/mod_authz_owner.html">mod_authz_owner</a></code></dt>
	<dd>A new module that authorizes access to files based
	on the owner of the file on the file system</dd>

	<dt><code class="module"><a href="./mod/mod_version.html">mod_version</a></code></dt>
	<dd>A new module that allows configuration blocks to be enabled based on the
	version number of the running server.</dd>

	<dt><code class="module"><a href="./mod/mod_info.html">mod_info</a></code></dt>
	<dd>Added a new <code>?config</code> argument which will show
	the configuration directives as parsed by Apache, including
	their file name and line number. The module also
	shows the order of all request hooks and additional
	build information, similar to <code>httpd -V</code>.</dd>

	<dt><code class="module"><a href="./mod/mod_ssl.html">mod_ssl</a></code></dt>

	<dd>Added a support for
	<a href="http://www.ietf.org/rfc/rfc2817.txt">RFC 2817</a>, which
	allows connections to upgrade from clear text to TLS encryption.</dd>

	<dt><code class="module"><a href="./mod/mod_imagemap.html">mod_imagemap</a></code></dt>
	<dd><code>mod_imap</code> has been renamed to
	<code class="module"><a href="./mod/mod_imagemap.html">mod_imagemap</a></code> to avoid user confusion.</dd>
	</dl>

	</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="programs" id="programs">Program Enhancements</a></h2>

	<dl>
	<dt><code class="program"><a href="./programs/httpd.html">httpd</a></code></dt>
	<dd>A new command line option <code>-M</code> has been added that
	lists all modules that are loaded based on the current
	configuration. Unlike the <code>-l</code> option, this list
	includes DSOs loaded via <code class="module"><a href="./mod/mod_so.html">mod_so</a></code>.</dd>

	<dt><code class="program"><a href="./programs/httxt2dbm.html">httxt2dbm</a></code></dt>
	<dd>A new program used to generate dbm files from text input,
	for use in <code class="directive"><a href="./mod/mod_rewrite.html#rewritemap">RewriteMap</a></code>
	with the <code>dbm</code> map type.</dd>
	</dl>
	</div><div class="top"><a href="#page-header"><img alt="top" src="./images/up.gif" /></a></div>
	<div class="section">
	<h2><a name="developer" id="developer">Module Developer Changes</a></h2>

	<dl>
	<dt><a class="glossarylink" href="./glossary.html#apr" title="see glossary">APR</a> 1.0 API</dt>

	<dd>Apache 2.2 uses the APR 1.0 API. All deprecated functions and
	symbols have been removed from <code>APR</code> and
	<code>APR-Util</code>. For details, see the
	<a href="http://apr.apache.org/">APR Website</a>.</dd>

	<dt>Authn/Authz</dt>
	<dd>The bundled authentication and authorization modules have
	been renamed along the following lines:
	<ul>
	<li><code>mod_auth_*</code> -> Modules that implement an HTTP
	authentication mechanism</li>
	<li><code>mod_authn_*</code> -> Modules that provide a backend
	authentication provider</li>
	<li><code>mod_authz_*</code> -> Modules that implement
	authorization (or access)</li>
	<li><code>mod_authnz_*</code> -> Module that implements both
	authentication & authorization</li>
	</ul>
	There is a new authentication backend provider
	scheme which greatly eases the construction of new authentication
	backends.</dd>

	<dt>Connection Error Logging</dt>

	<dd>A new function, <code>ap_log_cerror</code> has been added to log
	errors that occur with the client's connection. When logged,
	the message includes the client IP address.</dd>

	<dt>Test Configuration Hook Added</dt>

	<dd>A new hook, <code>test_config</code> has been added to aid
	modules that want to execute special code only when the user passes
	<code>-t</code> to <code class="program"><a href="./programs/httpd.html">httpd</a></code>.</dd>

	<dt>Set Threaded MPM's Stacksize</dt>

	<dd>A new directive, <code class="directive"><a href="./mod/mpm_common.html#threadstacksize">ThreadStackSize</a></code> has been added to
	set the stack size on all threaded MPMs. This is required
	for some third-party modules on platforms with small default
	thread stack size.</dd>

	<dt>Protocol handling for output filters</dt>

	<dd>In the past, every filter has been responsible for ensuring
	that it generates the correct response headers where it affects
	them. Filters can now delegate common protocol management to
	<code class="module"><a href="./mod/mod_filter.html">mod_filter</a></code>, using the
	<code>ap_register_output_filter_protocol</code> or
	<code>ap_filter_protocol</code> calls.</dd>

	<dt>Monitor hook added</dt>
	<dd>Monitor hook enables modules to run regular/scheduled jobs
	in the parent (root) process.</dd>

	<dt>Regular expression API changes</dt>

	<dd>The <code>pcreposix.h</code> header is no longer available;
	it is replaced by the new <code>ap_regex.h</code> header. The
	POSIX.2 <code>regex.h</code> implementation exposed by the old
	header is now available under the <code>ap_</code> namespace
	from <code>ap_regex.h</code>. Calls to <code>regcomp</code>,
	<code>regexec</code> and so on can be replaced by calls to
	<code>ap_regcomp</code>, <code>ap_regexec</code>.</dd>

	<dt>DBD Framework (SQL Database API)</dt>

	<dd><p>With Apache 1.x and 2.0, modules requiring an SQL backend
	had to take responsibility for managing it themselves. Apart
	from reinventing the wheel, this can be very inefficient, for
	example when several modules each maintain their own connections.</p>

	<p>Apache 2.1 and later provides the <code>ap_dbd</code> API for
	managing database connections (including optimised strategies
	for threaded and unthreaded MPMs), while APR 1.2 and later provides
	the <code>apr_dbd</code> API for interacting with the database.</p>

	<p>New modules SHOULD now use these APIs for all SQL database
	operations. Existing applications SHOULD be upgraded to use it
	where feasible, either transparently or as a recommended option
	to their users.</p></dd>
	</dl>
	</div></div>
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