Timer in Drools Fusion not working

Question

I am trying to run following rules in Drool Fusion( Version 5.4.1 ), but it's not working.

Ideally it should print "HELLO WORLD" every 7 seconds, it's not even triggering once.

Can anybody please help me to understand the timer in Drools?

     import com.drools.message.Message

rule "Test" 
    timer(int: 7s 7s)
when
    message:Message (type=="Hello")
then
    System.out.println("Hello World, Drools! " + message.getMsgtext());
end

   My code to run the above Rule is:

public class TestDrools {

  private static String DRL_FILE = "test_drools.drl";
  private static KnowledgeBuilder kbuilder = KnowledgeBuilderFactory
          .newKnowledgeBuilder();
  private static Collection pkgs;
  private static KnowledgeBase kbase = KnowledgeBaseFactory
          .newKnowledgeBase();
  private static StatefulKnowledgeSession ksession;

  private static WorkingMemoryEntryPoint entryPoint;

  public static void main(String[] args) {
      init();
      while (true) {
          Message msg = new Message();
          msg.setType("Hello");
          msg.setMsgtext("1");
          ksession.insert(msg);
      }
  }

  private static void init() {
      initialiseDrools();
  }

  private static void initialiseDrools() {
      kbuilder.add(ResourceFactory.newClassPathResource(DRL_FILE),
              ResourceType.DRL);
      if (kbuilder.hasErrors()) {
          System.out.println(kbuilder.getErrors().toString());
          throw new RuntimeException("Unable to compile drl\".");
      }
      pkgs = kbuilder.getKnowledgePackages();
      KnowledgeBaseConfiguration config = KnowledgeBaseFactory
              .newKnowledgeBaseConfiguration();
      config.setOption(EventProcessingOption.STREAM);
      kbase = KnowledgeBaseFactory.newKnowledgeBase(config);
      kbase.addKnowledgePackages(pkgs);
      KnowledgeSessionConfiguration conf = KnowledgeBaseFactory
              .newKnowledgeSessionConfiguration();
      conf.setOption(ClockTypeOption.get("pseudo"));
      ksession = kbase.newStatefulKnowledgeSession(conf, null);
      entryPoint = ksession.getWorkingMemoryEntryPoint("entryone");
      new Thread() {
          @Override
          public void run() {
              ksession.fireUntilHalt();
          }
      }.start();
  }
}

Thank you -Sanjay

I take it you're running fireUntilHalt()? It might be worth showing your API code. — Steve, Jan 06 '14 at 09:36
new Thread() { @Override public void run() { ksession.fireUntilHalt(); } }.start(); } — user3164370, Jan 06 '14 at 10:26
I have edited the post to add code I am using to test the rule. — user3164370, Jan 07 '14 at 15:30

score 1 · Answer 1 · answered Jan 08 '14 at 16:09

As per @laune's comment, you've used the pseudo clock. If you want to use the realtime clock, change the following line:

  conf.setOption(ClockTypeOption.get("realtime"));

Or just remove the line altogether - realtime is the default clock.

If you want to use the pseudo clock, you'll need to advance it yourself. This is typically use in unit testing, e.g.

  SessionPseudoClock  clock = ksession.getSessionClock();
  // insert some facts ... 
  clock.advanceTime(1, TimeUnit.HOURS);
  ksession().fireAllRules();

  // Do your unit test asserts / verify mocks here to verify that 
  // time-reasoned rules were / weren't fired

Note that, in general, alternative inserts and andvances executed in a separate thread, in parallel to the one can be used, too. -- Or the sequence posted by Stuart: advance/[insert/advance/fire can be executed repeatedly. — laune, Jan 10 '14 at 08:01

score 0 · Answer 2 · answered Jan 06 '14 at 06:36

0

then condition happens when when condition fulfills,so you need to at least put eval(true) in when condition and trigger an insert into knowledgeSession so that the rule engine figure out what to do when some condition fulfills.

answered Jan 06 '14 at 06:36

Sachin Verma

3,712
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Thanks for the reply. I tried using "when eval(true)", but it's the same issue. If my understanding is right, by default with empty 'when' block means eval(true), correct me if I am wrong. – user3164370 Jan 06 '14 at 08:46
Yeah blank do means eval(true), but are you doing something that insert fact and trigger the rule runtime? – Sachin Verma Jan 06 '14 at 09:08
1

Yes, I am inserting custom Messages as fact into the session, which should trigger the rule. One more thing if I remove the timer, it works perfect, not sure what's happening with the timer. – user3164370 Jan 06 '14 at 10:19

Timer in Drools Fusion not working

2 Answers2