Hello list!
I have a question concerning something like "persistent facts"...
I deal with problems where I have to reason about states (stored persistently in relational databases) and events (e.g. insert, update, and delete events in a database). I can subscribe to the events and then actively assert a corresponding "event fact". The question is how to efficiently deal with "state facts" corresponding to relational tuples.
A relation corresponds to a JESS template defining an unordered fact:
(deftemplate <relation-name>
(slot <column-1> ...)
...
(slot <column-n> ...)
)
Each tuple corresponds to one fact, e.g.:
(<relation-name> (<column-1> <val-1>) ... (<column-n> <val-n>)).
How can I use these "state facts" in JESS rules
- elegantly (yes, I do like "beautiful" code ;-))
- in a uniform fashion (rendering itself to generation mechanisms)
- on-demand (without prior "bulk assertion")
It would be nice to be able to write a rule like the following:
(defrule myrule
(some-triggering-event (key ?val) ...)
(<relation-name> (key ?val) (<column-1> <val-1>) ... (<column-n> <val-n>))
=>
(assert (some-other-fact (key ?val) (<column-1> <val-1>) ... (column-n> <val-n>)))
)
What would be the best way to solve this problem? I think a good solution could be of very general use...
Greetings
Thomas Barnekow
________________________________
Dipl.-Inform. Thomas Barnekow
Fraunhofer IAO, Competence Center Software Technology
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