[rules-users] Why isn't my rule firing??

[Greg Barton]

This is by design.  Unless you modify an object and inform the inference engine of the change, rule conditions will not be re-evaluated.  If you want the rule to re-fire you must tell the engine to reconsider the old NotificationEvents via update() or modify().  A rule like this would do it every time a new MyBean is detected:

rule "TouchAllNotificationEvents"
     dialect "mvel"
     when
          MyBean()
          $ne : NotificationEvent()
     then
          update($ne);
end

--- On Wed, 1/18/12, dunnlow <dunnlow at yahoo.com> wrote:

> From: dunnlow <dunnlow at yahoo.com>
> Subject: [rules-users] Why isn't my rule firing??
> To: rules-users at lists.jboss.org
> Date: Wednesday, January 18, 2012, 1:47 PM
> First, my intent:
> 
>   1) insert a pojo into a stateful session
>   2) based upon that pojo's attributes, create and
> insert a new fact
> (different type)
>   3) retract the initial pojo, but keep the newly
> created fact in memory for
> some period of time
> 
> After some helpful insight from the forum, I thought I
> could knock this out.
> 
> However, I'm stuck and I've boiled down to what I imagine
> is a
> misunderstanding that I have.  I have the code and
> rules below.  
> 
> With each fact that I insert, I expected 
>   1) to see the number of facts grow (the list of
> facts printed line 16 does
> grow with each call).  This works
>   2) to see the NotificationEvent added only once to
> working memory (the
> facts printed shows only one NotificationEvent and then a
> new MyBean for
> each one I insert).  So, I think this works also.
>   3) BUT, each time I call fireAllRules(), I expect
> the "foundNE" rule to be
> triggered and to see "Found A notification event"
> printed.  However, this is
> only printed once - after my first insert. Also, I see that
> 0 rules get
> fired (line 13) after the first MyBean insert.
> 
> SO, if I see a NotificationEvent in the list of facts in
> line 17, why isn't
> my foundNE rule printing out the message each time I insert
> a new MyBean and
> call fireallrules??
> 
> FYI, my future plan is to have a rule with low salience
> that retracts the
> MyBeans just inserted and have my foundNE rule retract any
> NotificationEvents that are at least 10 mins old.  (so
> that the
> NotificationEvents will grow but not MyBeans) .
> 
> Here is my test code (please excuse typos - there are none
> in my code):
> 
> Thanks very much for any insight.
> -J
> 
> ===test.java ===============
> 
> 1  KnowledgeBase kbase = readKnowledgeBaseFromFile();
> 2  StatefulKnowledegeSession ksession =
> kbase.newStatefulKnowledgeSession():
> 3  KnowledgeRuntimeLogger logger =
> KnowledgeRuntimeLoggerFactory.newFileLogger(ksession,"testlog");
> 
> 4  for (int x=0;x<10;x++){
> 5    myBean mb = new MyBean();
> 6     mb.setName("me");
> 7     mb.setHeadline("my_head");
> 8    mb.setTag("tagline");
> 9
> 10    List<Command> cmds = new
> ArrayList<Command>();
> 11    FactHandle fh = (FactHandle)
> ksession.insert(seb);
> 12    int rf = ksession.fireAllRules();
> 13    System.out.println(rf+"rules fired");
> 14
> 15    Collection<FactHandle> c =
> ksession.getFactHandles();
> 16    for (FactHandle f:c) {
> 17       
> System.out.println("  now: "+f.toString());
> 18    }
> 19
> 20    Thread.sleep(5000);
> 21 }
> 
> === test.drl ================
> import com.me.MyBean
> import java.util.Calendar
> 
> declare NotificationEvent
>     name: String
>     headline: String
>     tagline: String
>     dts: Long
> end
> 
> rule "foundNE"
>     dialect "mvel"
>     when
>         $ne :
> NotificationEvent()
>     then
>        
> System.out.println("Found a Notification Event");
> end
> 
> rule "NotTemplate_1"
>     dialect "mvel"
>     when
>         $myb : MyBean(name
> matches "me", headline matches "my_head")
>         not ($ne :
> NotificationEvent(name matches $myb.name,
> headline=$myb.headline)
>     then
>         NotificationEvent
> fact0 = new NotificationEvent();
>        
> fact0.setName($myb.name);
>        
> fact0.setHeadline($myb.headline);
>         insert(fact0);
>        
> System.out.println("Adding a notification event");
> end
> 
> --
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