Looking at the source, the only thing I can come up with is that maybe
a change event is coming in during a bload call, so that the engine is
not fully baked at the time. Is this possible?
On Mar 4, 2010, at 7:56 AM, bohlken wrote:
Hello,
in our Java application we use several Jess engines and shadow
facts. When
copying an engine with bsave and bload we sometimes get a curios
problem. We
have shadow facts TimePoint:
public class TimePoint
implements Serializable, Logging
{
private transient PropertyChangeSupport pcs;
private ArrayList<PropertyChangeListener> pcls;
private String name;
private long tMin;
private long tMax;
private boolean integrated;
.
public TimePoint()
{
...
pcls = new ArrayList<PropertyChangeListener>();
pcs = new PropertyChangeSupport(this);
};
public void settMin (long tMin)
{
Long temp = this.tMin;
this.tMin = tMin;
pcs.firePropertyChange("tMin", new Long(temp), new
Long(tMin));
}
...
public void addPropertyChangeListener(PropertyChangeListener pcl)
{
pcls.add(pcl);
pcs.addPropertyChangeListener(pcl);
}
public void removePropertyChangeListener(PropertyChangeListener
pcl)
{
pcls.remove(pcl);
pcs.removePropertyChangeListener(pcl);
}
private void readObject(ObjectInputStream in) throws
IOException, ClassNotFoundException
{
in.defaultReadObject();
pcs = new PropertyChangeSupport(this);
for (PropertyChangeListener pcl: pcls)
{
pcs.addPropertyChangeListener(pcl);
}
}
}
After trying several versions, we thought that this is the right
solution.
When copying an engine with bsave and bload, the readObject() function
should register the listeners again. We also create a new
PropertyChangeSupport and declare it as transient (if we do not
create a new
PropertyChangeSupport we get the same error as listed below).
Now, after a while, when several copyings are done, we modify a
timePoint
fact - which exists in every engine - via rete.modify(.) in the
first 7
engines everything works fine, but in engine 8 we get the following
error:
----------------------------------------------------------------------------
Jess reported an error in routine modify.
Message: Error setting slot value.
at jess.FactList.modifyDefinstancedObject(FactList.java:396)
at jess.FactList.modify(FactList.java:287)
at jess.Rete.modify(Rete.java:673)
at jess.Rete.modify(Rete.java:654)
at jess.Rete.modify(Rete.java:620)
at main.Engines.modifyFact(Engines.java:219)
at main.Control.modifyFact(Control.java:381)
at
coFriend
.dataPreprocessing.DataProcessThread.process(DataProcessThread.java:
222)
at
coFriend
.dataPreprocessing.DataProcessThread.run(DataProcessThread.java:85)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.GeneratedMethodAccessor38.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at jess.SerializablePD.setPropertyValue(SerializablePD.java:58)
at jess.FactList.modifyDefinstancedObject(FactList.java:392)
... 8 more
Caused by: java.lang.NullPointerException
at jess.DefinstanceList.propertyChange(DefinstanceList.java:350)
at java.beans.PropertyChangeSupport.firePropertyChange(Unknown
Source)
at java.beans.PropertyChangeSupport.firePropertyChange(Unknown
Source)
at constraints.TimePoint.settMin(TimePoint.java:110)
... 13 more
Exception in thread "Thread-6" java.lang.RuntimeException: Error
setting
slot value
at main.Main.showErrorMessage(Main.java:303)
at coFriend.main.CFMain.showErrorMessage(CFMain.java:348)
at
coFriend
.dataPreprocessing.DataProcessThread.process(DataProcessThread.java:
256)
at
coFriend
.dataPreprocessing.DataProcessThread.run(DataProcessThread.java:85)
------------------------------------------------------------------
Is it normal that a shadow fact has more than 1 listener? I printed
out the
number of listeners, some timePoints have up to 6.
Does someone has an idea whats going wrong?
Thank you very much!
Wilfried Bohlken
Universtity Hamburg
--------------------------------------------------------------------
To unsubscribe, send the words 'unsubscribe jess-users
[email protected]'
in the BODY of a message to [email protected], NOT to the list
(use your own address!) List problems? Notify [email protected]
.
--------------------------------------------------------------------
---------------------------------------------------------
Ernest Friedman-Hill
Informatics & Decision Sciences Phone: (925) 294-2154
Sandia National Labs
PO Box 969, MS 9012 [email protected]
Livermore, CA 94550 http://www.jessrules.com
--------------------------------------------------------------------
To unsubscribe, send the words 'unsubscribe jess-users [email protected]'
in the BODY of a message to [email protected], NOT to the list
(use your own address!) List problems? Notify [email protected].
--------------------------------------------------------------------
