I think Candide Kemmler wrote:

> 
> - JESS/Fact Storage Provider Framework: looks very interesting indeed;
> only it's not much talked about; seems nobody's ever tested it with the
> DBMS's _I_ use: PostgreSQL and MySQL, if ever tested _at all_; Does it
> help to reduce the memory consumption of JESS ? If it does, why isn't it
> considered a VERY interesting piece of software, I mean it should be put
> on the homepage of JESS.

It -is- a very interesting piece of software. Having been written with
JDBC, it theoretically works with any RDBMS; if it doesn't, it's
fairly small so should be easy to modify. For certain kinds of
problems, yes, it can vastly reduce the amount of memory Jess would
need. 

> There's something I must be missing here: everybody talks about rules,
> yet managing persistence and transactions which is of course a major
> requirement for business systems seems to be completely overlooked. Very
> few systems that handle the persistence of rule engines seem to exist,
> and they seem to come from the initiatives of lonely researchers working
> for their own in their remote laboratories.

Well, that's why the JSR94 (javax.rules) API is being developed; it
tries to address these kinds of issues in a vendor-independent
way. The reference implementation of JSR94 is a driver for Jess, by
the way.

But in general, we each mean something different when we say "rule
engine" or "rule"; these terms are pretty fuzzy in terms of how many
different ways they are implemented. Some "rule engines" are really
meant to apply many rules to one object at a time, while others are
meant to apply one rule to many objects; still others, like Jess,
simultaneously work with many rules and many objects. Precisely what
is meant by a "transaction" or "persistence" becoimes hard to nail
down in light of this variation.

Finally, note that Jess is a programmer's library as well as an
application, and as such, it makes a good laboratory for
experimentation. This is not a statement that you can make about many
commercial rule engines.

---------------------------------------------------------
Ernest Friedman-Hill  
Distributed Systems Research        Phone: (925) 294-2154
Sandia National Labs                FAX:   (925) 294-2234
Org. 8920, MS 9012                  [EMAIL PROTECTED]
PO Box 969                  http://herzberg.ca.sandia.gov
Livermore, CA 94550

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