Edson et al: I rarely get involved with this kind of thing but since there are more than 10 emails on the same subject and since Mark Proctor, Edson Tirelli and Dr. Friedman-Hill really shouldn't be drawn into the discussion due to a "conflict of interest" matter, and my friend and fellow instigator PL/ (woolfel) has not commented, may I be so bold as to interject these few thoughts: 1. There are about 25 or more BRMS/rulebased systems presently being used throughout the world. In this space they seem to be grouped into commercial and free, or almost free for personal use. Commercial systems can range from a few thousand to a few million US Dollars. Free (or almost free systems - no such thing as a free lunch) systems will require lots of time and study to learn what the commercial guys can provide in a short period of time. Also, most commercial vendors usually have schools for training purposes. 2a. EJFH has frequently mentioned that Jess is for programmers. But, he has written a book, "Jess In Action", (a bit out of date by now but still spot-on applicable in most cases) and the on-line user's manual that is kept up to date really is quite good. Read it! Also, the Jess email list is quite as active as the Drools Users list and you can normally get a response within a few hours there. In addition, there is a 3rd party Fuzzy Jess for those who want a bit "more" expert system approach to their system. Jess comes with source code for an extra $100 but commercial applications have to be worked out with Sandia Labs. Unfortunately, Jess is NOT available (legally) outside the USA but is totally free (with source code) to military, government and/or students/teachers at approved universities. 2b. If you are using C/C++ as your main system, then CLIPS (C Language Interface to Production Systems) is quite good and could be considered a superset of Jess. In addition to the quite-excellent on-line manuals, they also have a book out by Dr. Joseph Girratano (University of Houston) and Gary Riley (formerly NASA but now independent) that is updated frequently and is on version 4 at the time of this email - I use the book for teaching CLIPS, CLIPS/R2 and, sometimes, to supplement the "Jess In Action" book By Dr. Friedman-Hill. Unfortunately, I haven't found a similar email list to the ones maintained by Drools or Jess. The latest version of CLIPS 6.3 compares quite favorably with OPSJ using Rete-2 on my performance testing. CLIPS also allows various optimization conflict resolution strategies and comes with source code if you want to change things up a bit. 3. Mark Proctor et cie developed Drools for the past few years and it was (years ago) a programmers-only language as well. Recently however they are moving more toward the BRMS space with Guvnor and other tools to make it easier for the business user to use, create and/or modify the rules; and to compete with ILOG and Advisor. They also have an active users email list and a developers email list. (PLEASE - do not take user questions to the developer list.) They still lack factory consulting but you can purchase factory phone-in tech support from Red Hat, their parent company, or advertise for a Drools consultant on their home page. In addition, there are two books on Drools (in addition to their on-line manual) available through Amazon, Barnes & Noble, Nerd Books, etc. 4 Commercial, Rete-based systems normally have an evaluation copy (usually a full working version that is time-bombed to quit working after an appropriate period of time.) The biggies here are FICO Blaze Advisor (COBOL and .NET as well), IBM/ILOG JRules (COBOL and .NET as well), Pega Rules as part of the PegaSystems, MindBox for Mortgage Systems, and many others. In addition to some kind of text rules, these tools usually employ highly sophisticated Decision Tables (spreadsheets), Decision Trees, Reporting tools, Trouble Shooting tools, Professional Services (Consulting), Factory technical support (of various levels), etc. They are not cheap (usually $25K per developer seat) but, then, nobody ever got fired for using one of them. Most use some form of enhanced Rete and Blaze Advisor uses Rete 2 licensed from Dr. Forgy discussed below. 5. Non-Rete Commercial systems that might be considered could be Rule Burst (now owned by Oracle that also owns the Rete-based Haley Expert Systems), Visual Rules or Corticon (and others) that are, more or less, spreadsheet-based rule maintenance tools. All of them have some kind of rule optimization in place. These eye-catching models are far more familiar to the business users - and probably to your IT group and would compare to the Decision Tables from FICO, ILOG or Drools. In addition, these companies also have Professional Services and/or telephone technical support available for a cost. I have found that 75% or more of most business applications do not actually need Rete but Rete is better for large, enterprise rulebased systems that need a high performance factor. 6. Prolog tools are abundantly available, usually free, and VisiRules (not Visual Rules) is a great commercial modeling tool if you are considering an expert system rather than just a gathering of rules. My experience is that Prolog doesn't scale well to massive numbers of problems but is much better for extremely complicated and/or complex problems. But, then, my experience with Prolog is limited to smaller problems so maybe I didn't approach it the right way. 7. For high-performance applications I always recommend that companies take a look at OPSJ from Production System Technologies (the company founded and still owned by Dr. Charles L. Forgy, the inventor of Rete.) OPSJ (Java) uses, a proprietary algorithm from Dr. Fory that is from 50 - 100 times faster than most simple Rete systems and usually 10 - 20 times faster than most of today's improved Java-based Rete systems. The cost of OPSJ was less than $10K about a year or so ago and has no run-time fees. Also, Dr. Forgy recently announced Rete-NT that is about 10-12 times faster than Rete-2 but is priced based on the number of CPUs being used, usually about $5K per CPU. Rete-NT is best for systems (such as Homeland Security, NASA or Military application) that need a rulebased system AND that need extremely high performance. PST also has the C/C++ based CLIPS/R2 and other systems available for certain situations. If you think that you need the performance from Rete-NT, (warning: personal plug here) give me a call, or email, and let's talk about it first. 8. May I suggest that if your firm is considering using one or the other of those discussed above, or any other BRMS / Rulebased System, that you call in a trusted, independent consultant, of which there are some walking the streets in these hard time, who has experience not only with these rulebased systems but maybe with many others as well. That consultant (not myself but I could recommend several) would be able to listen to the requirements and advise as to which system might be the best for your situation. Beware of those who are partners with only one or two major vendors because, right or wrong, that is the recommendation that you will get. Be prepared to pay for their services - they have spent 10 to 20 years (or more) working with most of these systems and they are well aware of the benefits and pitfalls of most of them. Hmmm... Just a few thoughts. But, this should be sufficient to explain that selecting the appropriate tool depends on the problem and the capabilities of the tools. Most times I have found that the company didn't need a rulebased system (sometimes erroneously call Business Rule Management System - BRMS) at all. Rather, it probably should have been coded in Java or C/C++; or even BASIC, FORTRAN or COBOL. But using a BRMS / Rulebased System / Expert System would look cool on a CV so the IT guys (or the business guys) recommended it as a stepping stone for their next position. Above all, once a tool has been selected, RTFM!! Read The Fabulous Manual!!! Before calling in or writing the email list. I have CC'd both the Drools email list and the Drools Developers email list in the event that I misspoke anything about their (or another) product. The very LAST thing that I want to do is start an email flurry (sometimes called a "flame war") on any of the lists. These are my own personal opinions and do not reflect the positions of any of the trade-marked companies above nor of my own company, KnowledgeBased Systems Corporation, in any way, shape, form nor fashion. SDG jco On Jan 1, 2011, at 7:14 PM, Edson Tirelli wrote: