Hi There

I’m new to drools.  I’ve just set up the Drools-Server and it is (finally!) working and serving my test rule-set.  The one thing that’s not working as I expect it is the rule ordering via salience.  This is my simple test rule set:

rule "General brain eating advice"

when

              p : Patient(eatsBrains == true)         

then

              p.setAdvice("Stop eating brains, or at least, try to cut down");    

end

rule "Zombie exception to brain eating advice"

salience -50

when

              p : Patient(eatsBrains == true, isZombie == true)

then

              p.setAdvice("Evidence suggests that the undead cannot contract Kuru or that the effects are irellevant given the " +

"patient's current zombified state.\nSuggest euthenasing patient lest he/she eat your (or someone " +

"else's) brains");            

end

The idea is that the first rule fires all the time unless the patient happens to be a zombie, in which case the exception rule (the second rule) kicks in.  Now, as I have it here, with the exception at salience at -50 it actually works, which is the opposite of what I was expecting.  I’d thought that I would have had to have the exception at a higher salience to fire first.  That was what I tried first but that didn’t work – everyone got the general advice, zombies included.

What am I misunderstanding here?

Thanks!

Peter.

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“It is very difficult to get a man to understand something when his tribal identity depends on his not understanding it” - Michael Bérubé on Republican climate change denial.