You can run your session with a pseudo-clock, advanced to the point in time that corresponds to your reference date. KnowledgeSessionConfiguration config = KnowledgeBaseFactory.newKnowledgeSessionConfiguration(); config.setOption(ClockTypeOption.get("pseudo")); StatefulKnowledgeSession session = knowledgeBase.newStatefulKnowledgeSession(config, null); SessionPseudoClock clock = session.getSessionClock(); // session clock := NOW clock.advanceTime( (new java.util.Date()).getTime(), TimeUnit.MILLISECONDS ); // session clock := TOMORROW clock.advanceTime(1, TimeUnit.DAYS); This rule would fire, today being the 5-Feb-2013. rule test date-effective "6-Feb-2013" date-expires "7-Feb-2013" when $i: Integer() then System.out.println( "Integer " + $i ); end On 05/02/2013, pdario <dario.piantanida(a)gmail.com&gt; wrote:

On 05/02/2013, pdario <dario.piantanida(a)gmail.com&gt; wrote: java.util.Date is not the session clock. The default clock's getCurrentTime returns System.currentTimeMillis() and the pseudo-clock returns whatever you set it to. You'll have to base all your calculations with dates in fact data on the value returned by the session clock. I suppose you'll want to do this in RHS code, so this is one approach: global MyClock myClock; rule "x" when $d : Date() // or (... $d: orderExpireDate,... ) then System.out.println( $d + " diff in days: " + myClock.daysTo( $d ) ); end This is a primitive implementation of MyClock: public class MyClock { private static final long MS_PER_DAY = 24*60*60*1000; public static SessionClock sessionClock; public MyClock( SessionClock sessionClock ){ this.sessionClock = sessionClock; } public int daysTo( Date d ){ long dTime = d.getTime(); int dDays = (int)((dTime - dTime % MS_PER_DAY)/MS_PER_DAY); long sTime = sessionClock.getCurrentTime(); int sDays = (int)((sTime - sTime % MS_PER_DAY)/MS_PER_DAY); return dDays - sDays; } }

Just for the record: this simple expression is sufficient. int dDays = (int)(dTime/MS_PER_DAY); Also take care: the regular clock follows Time, the pseudo clock stands still. -W On 06/02/2013, pdario <dario.piantanida(a)gmail.com&gt; wrote:

Moreover, it seems getSessionClock is for Statefull sessions only, but I'm working with Stateless ones. -- View this message in context: http://drools.46999.n3.nabble.com/How-to-pass-a-global-reference-date-to-... Sent from the Drools: User forum mailing list archive at Nabble.com.