Apache Webserver

Modular architecture

The Apache webserver has a modular architecture: its core includes only the most basic functionality. Additional features can then be added with modules.

Base modules

Some modules are by default already added to the core at compile time. These modules can be shown on the command line with the -l option of httpd:

Directives related to modules

A module can be loaded at startup of Apache with the LoadModule directive placed into the httpd.conf file.

Another directive related to modules is IfModule.

Apparently, these directives are themselves implented in a (base) module: mod_so.

Listing loaded modules

While the -l command line option shows base modules, the -M option lists the loaded modules:

$ apache/bin/httpd -l
 core_module (static)
 mpm_winnt_module (static)
 http_module (static)
 so_module (static)
 access_compat_module (shared)
 …

Apache Webserver

Modular architecture

Base modules

Directives related to modules

Listing loaded modules

See also