The server is described in the WWW94 hypertext.
(http://www.ai.mit.edu/projects/iiip/doc/cl-http/server-abstract.html)
You can obtain a Lisp Machine distribution or the sources.
Lisp Machine (Genera 8.3): ftp.ai.mit.edu:/pub/users/jcma/cl-http/lispm.reel-1
Non-lispm (Server Sources): ftp.ai.mit.edu:/pub/users/jcma/cl-http/sources.tar.Z
The main features include fully object-oriented implementation, typed
condition handling, and rapid prototyping in Common Lisp.
Ports to MAC Common Lisp, Lucid Common Lisp, and Franz Allegro Common Lisp are
underway.
If you would like to help with one of the ports, please send mail to the
developers at bug-cl-http@research.ai.mit.edu
A homepage will follow as the ports make the technology available to wider
communities.
Perhaps the CERN team will list this full-featured server in their list of
servers, even though it implements everything from scratch in its 6K lines of
LISP.