Why business rules? Why not expert systems?
James Taylor over at Fair Isaac has a really good list of "Why business rules?" I agree with most of the points, except the stuff about expert systems.
Maybe the question should be "why not expert systems?"
The dirty little secret is that a lot of the rule engines out there were originally called "expert systems" or "inference engines", then they were called "business rule engines", and today they are known as "business rule management systems. (See the business rules hype cycle)
Of course, everything is better today. And faster. And connected. When expert systems first came out, the Web wasn't even born yet, and PCs were running at 10 mHz.
The biggest problem we had at Mobil Oil between 1988-1994 when we were building the Global Expert System Strategy and Lube Knowledgebase Strategy was making and mailing floppy disks to all our affiliates.
I remember one day we were showing the customer (an executive in Mobil Marine division) a demo of the expert system, his comments were:
- This is like an intelligent checklist, it never asks un-needed or dumb questions!
- I like that I can click on an underlined word (a hyperlink) and popup a definition, photo, go to the next page, or whatever!
- This is not like our other DOS or mainframe apps. Our users will not like the fact that this works on a "one page at a time" metaphor,
- because we're forcing users to fill out information or answer questions on the page (screen), then they have to press enter to go to the next page (screen).
That one page at a time metaphor he described was basically how the World Wide Web works. We were doing this in a business rule engine (BRE), aka an expert system (ES) in 1988. Before WWW. Before Windows.
(Want proof, go here and click on the photo on the right. There's a picture from back then, in my younger days... the program on the PC behind me is 1DirPlus or something like that.... Definately B.W. Before Windows). And so back then we built expert systems that did reasoning, chaining, hypertext / linking, and of course inferencing. Basically they would fire rules exactly the same way a modern rule engine would today. And give the same answer the expert would give,
Even after the experts retired long ago!
We did that in AION. We could have used Neuron Data (which evolved into Fair Isaac Blaze Advisor), or we could have done it in ILOG. Or any number of other ES tools at the time. Some of them are still around today. (See BRE Family Tree)
Distribution of expert systems, and access, is one of the reasons they "never took off". People used to say expert systems were a solution looking for a problem. Deploying expert systems on the web solves those problems.
I think the Web is "the problem" that expert systems were looking for. The Semantic Web is reigniting a lot of the good stuff from the AI/ES days. Adding intelligence and reasoning to applications is what expert systems have been doing all along.
And by the way, not everyone agrees that expert systems never took off. I certainly don't.
As Richard Barfus, CEO of MindBox, (an ES/BRE/BRMS firm) likes to say, "Expert systems didn't really go away. They went undercover."