I contacted Neophytos as Dan W. suggested after being unable to find xotcl information either here or on the aolserver list. Neophytos replied:
First of all, XOTcl *is* thread safe -- Zoran made sure that it is. All
you have to do in order to use xotcl under aolserver is to apply a
simple patch on your aolserver source code, replace namespace.tcl with
the file provided in the patch, and copy another xotcl-specific file in
the patch under your modules/tcl directory. The patch is available on
the xotcl website with detailed information.
Zoran has been using XOTcl for his company projects and it is also used
by Gustaf Neumann and his students/collaborators at the University of
Economics and Business Administration (WU) in Vienna, Austria. I've been
using XOTcl for the past few months (since Feb'02) and I plan to use
more of XOTcl for the development of a new-system that I've designed
this summer.
... You might also
want to join the xotcl mailing list (low-traffic) or contact Gustaf and
Zoran -- both are very friendly and they have intimate knowledge about
systems development.
The patch Neophytos mentions is available at the
xotcl download page. Here is the
readme.