KIE Community

Live Querries

Drools has always had query support, but the result was returned as an iterable set; this makes it hard to monitor changes over time. Live Querries have a listener attached instead of returning an iterable result set. These live querries stay open creating a view and publish change events for the contents of this view.

ViewChangedEventListener listener = new ViewChangedEventListener() {       
public void rowUpdated(Row row) {
updated.add( row.get( "$price" ) );
}

public void rowRemoved(Row row) {
removed.add( row.get( "$price" ) );
}

public void rowAdded(Row row) {
added.add( row.get( "$price" ) );
}
};   

// Open the LiveQuery
LiveQuery query = ksession.openLiveQuery( "cheeses",
                                      new Object[] { "cheddar", "stilton" },
                                      listener );

Timers and Calendars

Rule’s now suport both interval and cron based timers, which replace the now deprecated duration attribute.

timer ( int: <initial delay> <repeat interval>? )
timer ( int: 30s )
timer ( int: 30s 5m )

timer ( cron: <cron expression> )
timer ( cron:* 0/15 * * * ? )

Calendars can now controll when rules can fire. The Calendar api is modelled on Quartz :

public interface Calendar { 
 boolean isTimeIncluded(long timestamp);
}

Quartz provides several good Calendar implementations, so it makes sense to leverage those, for this we we provide an adapter helper method:

Calendar QuartzHelper.quartzCalendarAdapter(org.quartz.Calendar quartzCal)

Calendars are registered with the StatefulKnowledgeSession:

ksession.getCalendars().set( "week day", weekDayCal );

Which means they can now be used in rules. They can be used in conjunction with normal rules and rules including timers.

The rule calendar attribute can have one or more calendar names.
calendars “calname”
calendars “calname1”, “calname2”

Drools Spring integration

Drools Flow easy configuration

We keep improving the integration with Spring Framework. We added support for configuring a Drools Flow JPA session for using it with a local transaction manager.
(Now if you don’t need to configure variable persisters the jpaSessionServiceFactory is only one line! :))
More info and usage examples in: http://blog.bauna.com.ar/index.php/2010/05/drools-flow-configuration-using-spring/

Installation script

The Drools build now contains an install folder that simplifies installing the Eclipse plugin, Guvnor and the gwt-console. It creates and copies the necessary jars and wars and deploys them to the JBoss AS. It also includes a simple evaluation process example you can use to test your setup. For more info, take a look at the readme in the install folder.

JMX Monitoring improvements

        StatefulKnowledgeSession ksession = ...

// ... insert facts, fire rules, etc

SessionInspector inspector = new SessionInspector( ksession );
StatefulKnowledgeSessionInfo info = inspector.getSessionInfo();

        String report = SessionReporter.generateReport( "simple", info, null );