Apache HTTP Server Version 2.2
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 2.0 new features document.
mod_authn_alias
module
can greatly simplify certain authentication configurations.
See module name changes, and
the developer changes for more
information about how these changes affects users and module
writers.mod_cache
, mod_disk_cache
, and
mod_mem_cache
have undergone a lot of changes, and
are now considered production-quality. htcacheclean
has been introduced to clean up mod_disk_cache
setups.prefork
, worker
and
event
MPMs now allow httpd
to be shutdown gracefully via the
graceful-stop
signal. The GracefulShutdownTimeout
directive
has been added to specify an optional timeout, after which
httpd
will terminate regardless of the status
of any requests being served.mod_proxy_balancer
module provides
load balancing services for mod_proxy
.
The new mod_proxy_ajp
module adds support for the
Apache JServ Protocol version 1.3
used by
Apache Tomcat.httpd
can be
configured to use a system installation of PCRE by passing the
--with-pcre
flag to configure.mod_filter
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.event
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.mod_dbd
, together with the apr_dbd framework,
brings direct SQL support to modules that need it. Supports
connection pooling in threaded MPMs.
mod_auth_basic
and
mod_authn_file
; mod_auth_dbm is now called
mod_authn_dbm
; mod_access has been renamed
mod_authz_host
. There is also a new
mod_authn_alias
module for simplifying
certain authentication configurations.
mod_authnz_ldap
mod_auth_ldap
module to the 2.2 Authn/Authz
framework. New features include using LDAP attribute values and
complicated search filters in the
Require
directive.mod_authz_owner
mod_version
mod_info
?config
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 httpd -V
.mod_ssl
mod_imagemap
mod_imagemap
to avoid
user confusion.httpd
-M
has been added that
lists all modules that are loaded based on the current
configuration. Unlike the -l
option, this list
includes DSOs loaded via mod_so
.httxt2dbm
RewriteMap
with the dbm
map type.APR
and
APR-Util
. For details, see the
APR Website.ap_log_cerror
has been added to log
errors that occur with the client's connection. When logged,
the message includes the client IP address.test_config
has been added to aid
modules that want to execute special code only when the user passes
-t
to httpd
.ThreadStackSize
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.mod_filter
, using the
ap_register_output_filter_protocol
or
ap_filter_protocol
calls.pcreposix.h
header is no longer available;
it is replaced by the new ap_regex.h
header. The
POSIX.2 regex.h
implementation exposed by the old
header is now available under the ap_
namespace
from ap_regex.h
. Calls to regcomp
,
regexec
and so on can be replaced by calls to
ap_regcomp
, ap_regexec
.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.
Apache 2.1 and later provides the ap_dbd
API for
managing database connections (including optimised strategies
for threaded and unthreaded MPMs), while APR 1.2 and later provides
the apr_dbd
API for interacting with the database.
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.