Apache Reference: mod_so
mod_so - Dynamic Shared Object (DSO) Bootstrapping
Since Apache 1.2, src/modules/standard/mod_so.c
Robert S. Thau, Alexei Kosut, Paul Sutton, Ralf S. Engelschall (1996)
mod_so is a very interesting module. It supports the DSO facility, which Apache provides for building modules as stand-alone units (shared object files) and loading them at runtime into the address space of the
httpdprocess. Thus, although mod_so is implemented as a module, it provides some bootstrapping functionality for other modules that one usually would expect to find inside http_core.