What is 'JESS'?
JESS stands for Java Expert System Shell.
JESS is a rule engine and scripting environment written entirely in Java. Jess was originally inspired by the CLIPS expert system shell, but has grown into a complete, distinct, dynamic environment of its own. Using Jess, you can build Java software that has the capacity to "reason" using knowledge you supply in the form of declarative rules. Jess is small, light, and uses a fast rule engine.
The core Jess language is still compatible with CLIPS, in that many Jess scripts are valid CLIPS scripts and vice-versa. Like CLIPS, Jess uses the Rete algorithm to process rules, a very efficient mechanism for solving the difficult many-to-many matching problem (see for example "Rete: A Fast Algorithm for the Many Pattern/ Many Object Pattern Match Problem", Charles L. Forgy, Artificial Intelligence 19(1982), 17-37.) Jess adds many features to CLIPS, including backward chaining, working memory queries, and the ability to manipulate and directly reason about Java objects. Jess is also a powerful Java scripting environment, from which you can create Java objects and call Java methods without compiling any Java code.
For more information about JESS, visit the JESS Home Page.