http://www.jessrules.com/jess/docs/70/functions.html#watch

Watch allows you to see when various things happen in the Jess system, such as:

• Rule activations
• Rule firings
• Construct compilations
• Fact assertions and retractions
• Module focus changes

   http://www.jessrules.com/jess/docs/70/functions.html#set-watch-router

Watch is good in that it will show you everything that’s happening in the system, but sometimes it’s just too much data to shift through. This is especially true when you're trying to determine what facts in working memory are causing a rule to fire.

The most powerful utility I’ve found for debugging my Jess programs is the simple jess.Main console application. From this command-line application, you can examine what facts are in working memory: "(facts)", see what rule activations are on the agenda: "(agenda)", and step through the rule firings one at a time: "(run 1)".

Unfortunately, Jess expert systems in real applications are usually embedded into larger Java programs, which makes accessing the command loop more difficult. This CommandLoop function may allow you to explicitly start the console from an otherwise back-end process.

StepFunction	Fire one single rule and output the agenda for all modules in the focus stack.
AllAgenda	Output the agendas for each module in the focus stack.
NextAgenda	Output the agenda for the next module in the focus stack.
ListAllFacts	List all the facts accross all the different modules in the system.
CommandLoop	Explicitly start a command-loop from within your expert system.
WatchRouter	Direct watch information to different routers.

Submitted by:
GeorgeWilliamson
Union Pacific Railroad
gawillia@up.com

Thanks, George! - JM