JESS: Fact modified and JessListener

[Nguyen, Son]

Hi,

My goal is to capture fact modification events for shadow facts.
I have a Java class which I use to create a def template:

(import FactChanged)

(deftemplate FactChanged
        (declared (from-class FactChanged)
                (include-variables TRUE)))

I define the following to capture fact modification events:

(deffunction display-fact-modified-from-event (?evt)
    (bind ?ets (?evt toString))
    (bind ?et (?evt getType))
    (bind ?et1 (get ?evt type))
    (if (eq ((bit-or (JessEvent.FACT) (JessEvent.MODIFIED)) (get ?evt
type)) then
    (printout t "modified fact:" (call (call ?evt getObject) getName)
crlf))))

; install the above function using a JessEventAdapter
(call (engine) addJessListener
    (new JessEventAdapter display-fact-modified-from-event (engine)))

; add FACT|MODIFIED to the event mask
(set (engine) eventMask
(bit-or (get (engine) eventMask) (JessEvent.MODIFIED) (JessEvent.FACT)))

I add a new Java object

; create a new instance of FactChanged
(bind ?data (new FactChanged))
(add ?data)

I then get the shadow fact and modify it

(bind ?datafact (call (engine) getShadowFactForObject ?data))
(modify ?datafact (data "Once Upon A Time"))

I expected to receive an event for fact modified but did not receive.
Using JessDE to look at the event type I saw 16, which is
JessEvent.Fact.

I can capture fact assertions but not fact modifications.
This seems to be related to the fact being a shadow fact instead of a
regular fact.

The java class is simple:

public class FactChanged implements Serializable {

        private PropertyChangeSupport pcs = new
PropertyChangeSupport(this);
        public String data;

        public FactChanged () {
                data = "original";
        }
        public String getData() {
                return data;
        }

        public void setData(String data) {
                String oldData = this.data;
                this.data = data;
                pcs.firePropertyChange("FactChanged ", oldData, data);
                System.out.println("DataChanged occurred");
        }

        public void addPropertyChangeListener(PropertyChangeListener
pcl) {
                pcs.addPropertyChangeListener(pcl);
        }

        public void removePropertyChangeListener(PropertyChangeListener
pcl) {
                pcs.removePropertyChangeListener(pcl);
        }
}


Any help will be appreciated.

Son Nguyen.