Hi - we have licensed JESS and are using it in a commercial application for 2.5
years now. While I can't speak for the licensing process, we have made good
experiences with the technical side of things. It's easy to integrate, well
documented and the mailing list is generally responsive to
Back in 2002-2003 I used JESS to build a pre-trade compliance engine
for a trading platform.
JESS is a fantastic expert system shell. Like any other tool, the key
is taking time to learn how to use it. Logic programming is different
than imperative or OOP. The benefit is the result of how JESS is
Jess is involved here, but this is not a Jess problem per se. As the error
message says, a third-party Jess script called a Java method
loadOWLResource in some third-party code, and that Java method threw an
exception. Jess, in turn, throws an exception to report this. The Jess
exception object
This will not improve efficiency but here's a single rule doing the job, at
the cost of one additional fact.
(deftemplate driver (slot driverId) (slot score) (slot rank))
(deftemplate rover (slot rank))
(defrule rank-drivers
?d - (driver (score ?s1) (rank nil))
(not (driver (score ?s2:(
