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<title>Overview of new features in Apache HTTP Server 2.0</title>

<summary>

<p>This document describes some of the major changes between the

1.3 and 2.0 versions of the Apache HTTP Server.</p>

</summary>

<seealso><a href="upgrading.html">Upgrading to 2.0 from 1.3</a></seealso>

<section id="core">

<title>Core Enhancements</title>

<dl>

<dt>Unix Threading</dt>

<dd>On Unix systems with POSIX threads support, Apache can

now run in a hybrid multiprocess, multithreaded mode. This

improves scalability for many, but not all configurations.</dd>

<dt>New Build System</dt>

<dd>The build system has been rewritten from scratch to be

based on <code>autoconf</code> and <code>libtool</code>.

This makes Apache's configuration system more similar to

that of other packages.</dd>

<dt>Multiprotocol Support</dt>

<dd>Apache now has some of the infrastructure in place to

support serving multiple protocols. <module>mod_echo</module> has

been written as an example.</dd>

<dt>Better support for non-Unix

platforms</dt>

<dd>Apache 2.0 is faster and more stable on non-Unix

platforms such as BeOS, OS/2, and Windows. With the

introduction of platform-specific <a

href="mpm.html">multi-processing modules</a> (MPMs) and the

Apache Portable Runtime (APR), these platforms are now

implemented in their native API, avoiding the often buggy and

poorly performing POSIX-emulation layers.</dd>

<dt>New Apache API</dt>

<dd>The API for modules has changed significantly for 2.0.

Many of the module-ordering/-priority problems from 1.3 should

be gone. 2.0 does much of this automatically, and module ordering

is now done per-hook to allow more flexibility. Also, new calls

have been added that provide additional module capabilities

without patching the core Apache server.</dd>

<dt>IPv6 Support</dt>

<dd>On systems where IPv6 is supported by the underlying

Apache Portable Runtime library, Apache gets IPv6 listening

sockets by default. Additionally, the <directive

module="mpm_common">Listen</directive>, <directive module="core"

>NameVirtualHost</directive>, and <directive module="core"

>VirtualHost</directive> directives support

IPv6 numeric address strings (e.g., "<code>Listen

[2001:db8::1]:8080</code>").</dd>

<dt>Filtering</dt>

<dd>Apache modules may now be written as filters which act on

the stream of content as it is delivered to or from the

server. This allows, for example, the output of CGI scripts to

be parsed for Server Side Include directives using the

<code>INCLUDES</code> filter in <module>mod_include</module>. The

module <module>mod_ext_filter</module> allows external programs to

act as filters in much the same way that CGI programs can act as

handlers.</dd>

<dt>Multilanguage Error Responses</dt>

<dd>Error response messages to the browser are now provided in

several languages, using SSI documents. They may be customized

by the administrator to achieve a consistent look and feel.</dd>

<dt>Simplified configuration</dt>

<dd>Many confusing directives have been simplified. The often

confusing <code>Port</code> and <code>BindAddress</code> directives

are gone; only the <directive module="mpm_common">Listen</directive>

directive is used for IP address binding; the <directive

module="core">ServerName</directive> directive specifies the

server name and port number only for redirection and vhost

recognition.</dd>

<dt>Native Windows NT Unicode Support</dt>

<dd>Apache 2.0 on Windows NT now uses utf-8 for all filename

encodings. These directly translate to the underlying Unicode

file system, providing multilanguage support for all Windows

NT-based installations, including Windows 2000 and Windows XP.

<em>This support does not extend to Windows 95, 98 or ME, which

continue to use the machine's local codepage for filesystem

access.</em></dd>

<dt>Regular Expression Library Updated</dt>

<dd>Apache 2.0 includes the <a href="http://www.pcre.org/">Perl

Compatible Regular Expression Library</a> (PCRE). All regular

expression evaluation now uses the more powerful Perl 5

syntax.</dd>

</dl>

</section>

<section id="module">

<title>Module Enhancements</title>

<dl>

<dt><module>mod_ssl</module></dt>

<dd>New module in Apache 2.0. This module is an interface

to the SSL/TLS encryption protocols provided by

OpenSSL.</dd>

<dt><module>mod_dav</module></dt>

<dd>New module in Apache 2.0. This module implements the HTTP

Distributed Authoring and Versioning (DAV) specification for

posting and maintaining web content.</dd>

<dt><module>mod_deflate</module></dt>

<dd>New module in Apache 2.0. This module allows supporting

browsers to request that content be compressed before delivery,

saving network bandwidth.</dd>

<dt><module>mod_auth_ldap</module></dt>

<dd>New module in Apache 2.0.41. This module allows an LDAP

database to be used to store credentials for HTTP Basic

Authentication. A companion module, <module>mod_ldap</module>

provides connection pooling and results caching.</dd>

<dt><module>mod_auth_digest</module></dt>

<dd>Includes additional support for session caching across

processes using shared memory.</dd>

<dt><module>mod_charset_lite</module></dt>

<dd>New module in Apache 2.0. This experimental module allows

for character set translation or recoding.</dd>

<dt><module>mod_file_cache</module></dt>

<dd>New module in Apache 2.0. This module includes the

functionality of <code>mod_mmap_static</code> in Apache 1.3,

plus adds further caching abilities.</dd>

<dt><module>mod_headers</module></dt>

<dd>This module is much more flexible in Apache 2.0. It can now

modify request headers used by <module>mod_proxy</module>, and

it can conditionally set response headers.</dd>

<dt><module>mod_proxy</module></dt>

<dd>The proxy module has been completely rewritten to take

advantage of the new filter infrastructure and to implement a

more reliable, HTTP/1.1 compliant proxy. In addition, new

<directive module="mod_proxy" type="section">Proxy</directive>

configuration sections provide more readable (and internally

faster) control of proxied sites; overloaded <code>&lt;Directory

"proxy:..."&gt;</code> configuration are not supported. The module

is now divided into specific protocol support modules including

<code>proxy_connect</code>, <code>proxy_ftp</code> and

<code>proxy_http</code>.</dd>

<dt><module>mod_negotiation</module></dt>

<dd>A new <directive module="mod_negotiation"

>ForceLanguagePriority</directive> directive can be used to assure that

the client receives a single document in all cases, rather than

NOT ACCEPTABLE or MULTIPLE CHOICES responses. In addition, the

negotiation and MultiViews algorithms have been cleaned up to

provide more consistent results and a new form of type map that

can include document content is provided.</dd>

<dt><module>mod_autoindex</module></dt>

<dd>Autoindex'ed directory listings can now be configured to

use HTML tables for cleaner formatting, and allow finer-grained

control of sorting, including version-sorting, and wildcard

filtering of the directory listing.</dd>

<dt><module>mod_include</module></dt>

<dd>New directives allow the default start and end tags for SSI elements

to be changed and allow for error and time format configuration

to take place in the main configuration file rather than in the

SSI document. Results from regular expression parsing and grouping

(now based on Perl's regular expression syntax) can be retrieved

using <module>mod_include</module>'s variables <code>$0</code>

.. <code>$9</code>.</dd>

<dt><module>mod_auth_dbm</module></dt>

<dd>Now supports multiple types of DBM-like databases using the

<directive module="mod_auth_dbm">AuthDBMType</directive>

directive.</dd>

</dl>

</section>

</manualpage>