docs/manual/new_features_2_2.xml

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<manualpage metafile="new_features_2_2.xml.meta">

<title>Overview of new features in Apache 2.2</title>

<summary>
  <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>
</summary>

  <section id="core">
    <title>Core Enhancements</title>
    <dl>

      <dt>Authn/Authz</dt>
      <dd>The bundled authentication and authorization modules have
          been refactored.  There is a new authentication backend provider
          scheme which greatly eases the construction of new authentication
          backends.</dd>

      <dt>Caching</dt>
      <dd><module>mod_cache</module>, <module>mod_disk_cache</module>, and
          <module>mod_mem_cache</module> have undergone a lot of changes
          are now considered production-quality. <program>htcacheclean</program>
          has been introduced to cleanup <module>mod_disk_cache</module>
          setups.</dd>

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

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

      <dt>Smart Filtering</dt>
      <dd><module>mod_filter</module> 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>httpd 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 <module>event</module> MPM uses a seperate 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><module>mod_dbd</module>, together with the apr_dbd framework,
          brings direct SQL support to modules that need it.  Supports
          connection pooling in threaded MPMs.</dd>

    </dl>
  </section>

  <section id="module">
    <title>Module Enhancements</title>
    <dl>
      <dt><module>mod_authnz_ldap</module></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 
          <directive module="core">Require</directive> directive.</dd>

      <dt><module>mod_info</module></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><module>mod_ssl</module></dt>
      <!-- Need Info on SSLEngine Support? -->
      <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>
    </dl>
  </section>

  <section id="programs">
    <title>Program Enhancements</title>
    <dl>
      <dt><program>httpd</program></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 <module>mod_so</module>.</dd>
    </dl>
  </section>

  <section id="developer">
    <title>Module Developer Changes</title>
    <dl>
      <dt>APR 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>Connection Error Logging</dt>

      <dd>A new function, <code>ap_log_cerror</code> has been added to log
          errors that occure 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 <program>httpd</program>.</dd>

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

      <dd>A new directive, <code>ThreadStackSize</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
          <module>mod_filter</module>, 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>
    </dl>
  </section>
</manualpage>