The directory structure for this level is as follows: aaa/ This directory contains modules dealing with authorization and authentication. arch/ cache/ This directory houses modules that implement file and data caching capability. database/ The apache DBD framework manages connections to SQL backends efficiently. dav/ This directory houses modules that implement WebDAV functionality. echo/ experimental/ In this directory we've placed some modules which we think provide some pretty interesting functionality, but which are still in the early stages of development and could evolve radically in the future. This code isn't supported officially. filters/ This directory houses modules that perform general inline data filtering. generators/ This directory houses modules that perform data generation functions. http/ This directory houses modules that basic HTTP protocol implementation. loggers/ This directory houses modules that handle logging functions. mappers/ This directory houses modules that handle URL mapping and rewriting. metadata/ This directory houses modules that deal with Header metadata. proxy/ This houses the code for the proxy module for Apache. ssl/ This directory houses code for OpenSSL functionality. test/ This directory houses modules which test various components of Apache. You should not compile these into a production server.