What is AOL Server and ACS?
AOLserver is America Online’s Open-Source web server. Originally built by NaviSoft, before it was acquired by AOL, it is the backbone of one of the largest and busiest production environments in the world. AOLserver is a multithreaded, Tcl-enabled web server used for large scale, dynamic web sites. It was revised and released as open source in 1999. Phil Greenspun, the author of Philip and Alex’s Guide to Web Publishing strongly recommends AOL server and his company built their free ArsDigita Community System on AOLserver.
OpenAcs is a tookit for building web Applications, which runs on the AOL Web Server.