[rules-users] Trouble getting Dynamic Salience working - add in rules-templates

Thank you for the response Greg.  For starters, I did NOT know about specificity...  very helpful to know, and I feel certain I will be using it in the future.  I don't feel any of the documentation I've read on Drools really got this subject across for me, I not sure the the Drools developer book really covers it at all. Back to my actual implementation.  We are using rules-templates, which have a "unique behavior" I've been calling a feature, but some might consider a bug... or have found a way to work around.  Templates do not render rule lines which contains NULL parameters.  This hasn't bit my too badly to this point, but MAY pose an interesting issue for specificity (now that I know about it!) My real world example is a good bit more complicated.  My LH includes: PARAMETERS -------------------------- Product  - NOT NULL Start Date End State Price Group - NOT NULL State Group Some of the info is coming from a single instance of an object I'm calling "transporter" I use to gather info from other rules.  It will have a list of state groups and price groups.  So psuedocode for my template LH will look something like: template.pricegroups.contains( "@{PRICE_GROUP}" ) template.stategroups.contains( "@{STATE_GROUP}" ) policy (                 startDate > @{START_DATE}                 endDate < @{END_DATE}                 product = "@{PRODUCT}" ) The problem I run into here, is that in any given rule, only a subset of these will appear.  So one rule may produce: // this rules parameters have a NULL STATE_GROUP template.pricegroups.contains( "pg1" ) policy (                 startDate > 2009-01-01                 endDate < 2010-01-10}                 product = "prod1" ) and another might produce // this rule has a STATE_GROUP, but no START_DATE and END_DATE template.pricegroups.contains( "pg1" ) template.stategroups.contains( "NY" )  policy (                 product = "prod2" ) In this example, I actually want the SECOND rule to win the conflict.  It is "more specific" for our business rule, a policy for NY should match, but the the first rule should not.  In reality, the first rule has more facts, so which one will actually fire first by rules of specificity? My activation-group and salience hack was one workaround for this condition.  I set the second rule with a higher salience, and add them both to the same activation-group. I will try different combinations of rule-templates and specificity when I am in the office tomorrow (midnight here in San Diego.)  If you have any further feedback on this, I do appreciate your taking the time to show a Drools newbie some very useful stuff. Thanks! Bill Message: 2 Date: Tue, 1 Sep 2009 19:29:40 -0700 (PDT) From: Greg Barton <greg_barton(a)yahoo.com&gt; Subject: Re: [rules-users] Trouble getting Dynamic Salience working To: Rules Users List <rules-users(a)lists.jboss.org&gt; Message-ID: <52492.42683.qm(a)web81501.mail.mud.yahoo.com&gt; Content-Type: text/plain; charset="iso-8859-1" I hope you're not going through all of that trouble just to get the functionality from that concrete example.  You get that for free with Drools' default conflict resolution, which includes "specificity."  Specificity means that rules with the more specific conditions, and all else equal, are fired first.  So between these two rules, only the CheeseSausagePepperoniPepper one fires: rule "CheeseOnly"     when         p : Pizza( )         t1: Topping( pizza == p, name == "cheese" )     then         System.out.println( "Eating cheese pizza" );         retract( t1 );         retract( p ); end rule "CheeseSausagePepperoniPepper"     when         p : Pizza( )         t1: Topping( pizza == p, name == "cheese" )         t2: Topping( pizza == p, name == "sausage" )         t3: Topping( pizza == p, name == "pepperoni" )         t4: Topping( pizza == p, name == "pepper" )     then         System.out.println( "Eating cheese sausage pepperoni pepper pizza" );         retract( t4 );         retract( t3 );         retract( t2 );         retract( t1 );         retract( p ); end See the attached project. --- On Tue, 9/1/09, Bill Tarr <javatestcase(a)yahoo.com&gt; wrote: