Re: [rules-users] Not looping the rule when more then 1 valid match is found

It depends on what addResult() does and if you need the actual values of A() and B(). Forward chaining engines are "data driven" and as so, changes to your data (facts) are what cause the engine to cancel activations. So, if you don't need the actual values of A and B, use "exists": exists( A( $c : code) and B(parentCode == $c) ) Although, since addResult() uses them as parameters, I guess it is not the case. So, does addResult() changes your facts in any way? Lets say addResult() creates a Association fact between A and B, you could write: when $a : A( $c : code ) $b : B( parentCode == $c ) not( Association( <you can constraint something here if you want> ) ) then Or if A and B have an attribute that is set by addResult() when $a : A( $c : code ) $b : B( parentCode == $c ) not( A( resultAdded == true ) and B( resultAdded == true ) ) then So, in the end, rules in forward chaining are about taking actions triggered by a given data state. Write rules that react to the expected state and change the state accordingly. Oh, obviously you can always use fire limit or halt to "pause" the execution if that is what you want too. session.fireAllRules( 1 ); // fires only one rule and returns control to the application Or: when $a : A( $c : code ) $b : B( parentCode == $c ) then addResult( $a, $b ); drools.halt(); end After firing the above rule, stop firing rules and return the control to the application. Above situations will only pause the engine. All activations that were not fired will remain in the agenda waiting for the next call to fireAllRules() to be fired. []s Edson 2009/1/26 Maxim Veksler <maxim.veksler(a)gmail.com&gt; -- Edson Tirelli JBoss Drools Core Development JBoss, a division of Red Hat @ www.jboss.com