Re: [rules-users] how to ensure that one rule only is executed once?

You'd need to make sure you inform the engine that Order's price has changed:- when ... then modify( $o ) { setPrice( $o.getPrice() - 20); } You could also consider using agenda-groups or lock-on-active to provide your behaviour. *agenda-groups * rule "rule 1" //implied default agenda-group of MAIN when $o : Order (amount>100 && <200); then modify( $o ) { setPrice( $o.getPrice() - 10); } drools.setFocus("next step in calculation"); end rule "rule 2" //implied default agenda-group of MAIN when $o:Order (amount>200); then modify( $o ) { setPrice($o.getPrice() - 20); } drools.setFocus("next step in calculation"); end rule "rule 3" agenda-group "next step in calculation" when $o : Order(....) then .... end *lock-on-active* rule "rule 1" //implied default agenda-group of MAIN lock-on-active true when $o : Order (amount>100 && <200); then modify( $o ) { setPrice( $o.getPrice() - 10); } end rule "rule 2" //implied default agenda-group of MAIN lock-on-active true when $o:Order (amount>200); then modify( $o ) { setPrice($o.getPrice() - 20); } end rule "rule 3" agenda-group "next step in calculation" when $o : Order(....) then .... end On 18 March 2011 16:08, Gabor Szokoli <szocske(a)gmail.com&gt; wrote: