Multiple Apache         Dispatching and       Multithreaded Worker processes
processes running       coordinating server   Running on multiple nodes
on one or more nodes    running on a single   One connection  per thread
                        node (using 
                        IO::Select)

Client A  - socket -+           +- socket --> Worker 1a
Client B  - socket -+-> Server -+- socket --> Worker 1b
Client C  - socket -+           +- socket --> Worker 2a