Chuck,
I know this is not addressing the question you asked but I am curious why
you would be using an Expert System for a time and attendance system? I
have done several of these and it seems to me that the rules for such an
application are analytic and very well understood so a Database Management
system would be a better choice. But may be I am missing something?
Tom Savell
>-----Original Message-----
>From: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED] <[EMAIL PROTECTED]>
>Date: Monday, June 05, 2000 9:29 AM
>Subject: JESS: Questions on when to use Rule Based System
>
>
>>
>>
>>I've seen the recommendations on when to use a rule base system (RBS) (re.
>>thread "JESS: Need of a Rule Based System!!!" started by Sachin and the
>thread
>>"JESS: Data constraint management " started by Robert Quillen.) I wonder,
>>though, about when you have a REALLY big system. I am now working on a
>project
>>for a time and attendance system. I can imagine it handling ten to twenty
>>thousand employees. (So that would be ten to twenty thousand facts.) The
>rules
>>to pay these individuals are very complex (on the order of hundreds of
>rules).
>>Each employee would have two to six "clocking events" per day. (That
would
>>potentially be six times twenty thousand more facts.) There can be ten to
>a
>>hundred different people adding/changing facts at any given time.
>>
>>So I'd like to use an RBS, but can it handle it? I can't imagine keeping
>all
>>that data in memory. So how efficient would the engine be at
>>reading/representing this information in an SQL table? I've seen Thomas
>>Barkenow's RDBS extension. It basically is wrapper for creating
individual
>>SELECT statements for each rule to find it's facts. But I can't imagine
>that is
>>very efficient. It gets the job done, but it would be murder for a large
>>system. I can see a case where it would use two SELECT statements
instead
>of
>>using a JOIN.
>>
>>How efficient are these RBS when there is a large number of facts being
>>added/changed? What would happen if power was suddenly lost. Would
>anything
>>get lost? (That would be a bad thing, especially since we are dealing
with
>>people's pay!) How would it recover?
>>
>>In the case of JESS, how thread safe is it?
>>
>>-Chuck.
>>
>>
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