Re: [rules-users] function in drools

I would recommend you to read the drools manual and the examples, especially the introduction... rule based programming is somewhat different from more traditional procedural (e.g. java) programming. It may let you solve your problems efficiently and elegantly, or just give you headaches.. :) Now, as for the examples: 1) the "then" in a rule is a "when premise then conclusion", as in (a type of) "logic", not a "then" as in "first this then that", as in sequential programming. SO, the premise is about collecting (joining) and matching (selecting) data against patterns. This said, the accumulate has to be in the LHS, not in the RHS. 2) I guess you're trying to compare the average temperature against ? is $max the max temperature? Or a threshold you provide from somewhere else? 3) I also guess you want to use the average temperature in the other rule... As Wolfgang pointed out, you have to insert it in the working memory (or use a global, but this may not the best of practices). Moreover, it's more useful to use the value to create an instance of a more "meaningful" class than simply inserting a Number. What if other rules insert Numbers? 4) Maybe you also want to make the number related to the person? It's an interesting exercise on joins, to see what happens if you add that "foreign key" or not 5) You may not need to use agenda groups, if your rules are implicitly made sequential by the patterns. If a rule can only matched something potentially inserted by another, there is no way for that rule to fire until the other has been fired itself. declare AverageTempRecord // pers : Person avg : double end rule "MrFlow" when $pers : person : Person( gender == 'M' ) accumulate ( SensorReading( $temp : temperature ) over window:time( 10m ), $max : max( $temp ), // this is the max temperature over the window, but this can't be your "$max"... $avg : average( $temp ) // ; // $avg > MAX // where do you get the threshold from? ) then insertLogical( /*$pers,*/ new AverageTempRecord( $avg ) ); end rule "Hello MR" when $p : Person() $a : AverageTemperatureRecord( /* pers == $p, */ $avg : avg ) then System.out.println( "Hello mr " + $p.getName() + ", your temp is " + $avg ); retract( $p ); end Best Davide -- View this message in context: http://drools.46999.n3.nabble.com/function-in-drools-tp4020021p4020046.html Sent from the Drools: User forum mailing list archive at Nabble.com.