I tried to get a license at one time. For individual non-commercial, the cost is about $100. If you are working for a Federal agency, it is free but there is a mountain of paperwork to fill out. Universities and other schools can also get it free, but not students. I don�t know what the commercial cost is. There is a 30 day trial that is pretty good. I will give you a great idea on what it can and can�t do. If you want to understand about rule based expert systems, a very similar (and free) program is CLIPS. It isn�t java based but it is very worth while to play with to understand what that type of software can do.
We are evaluating Fair Issac Blaze ADvisor and Ilog JRules. they seem pretty good products, but their customer service is really very poor. Maybe opensource products will be the only alternative. Do you think so?
How do Jess compare against them? is a comparison between then viable. manning is publishing very good books, but they have a week international channel. but that belongs to another question. :-) regards and congratulation for your books
How does Jess compare to JRules and Blaze? Well, (sorry, another advertisement coming on...)
We think our technical support is the best in the business. We treat our customers like real programmers, and we only have programmers doing technical support -- no flowchart-following drones.
Only with Jess do you get source code for the engine, which gives you incredible flexibility.
Performance-wise, Jess has consistently tested faster than either of these products; not by a large margin, but consistently better.
Price-wise, Jess is very competitive (comparable or better.)
Feature-wise, Jess's rule language has innovative features like both forward and backward chaining, knowledge-base queries, dynamic updating of the rule base, property-change event support, and more.
So surely there must be disadvantages, too? There are some: the biggest one is turnkey-tool support. Jess is the rule engine for "real programmers." If you want a slick graphical tool that lets your manager enter his own rules (or at least, looks as though it could during the sales presentation!) then Jess can't do that for you. Some other more practical tools are missing too, especially a graphical debugger, which would be nice. But an Eclipse-based Jess IDE, including a rule editor and a debugger, is being developed for the next Jess release!
Very interesting. do you have a roadmap or schedule for those new tools? thanks note: It would be very useful to your prospective customers, to have a comparison document. remember that they have big marketing budgets :-)