3:28 a.m.
Hi all drools users!
I'm just learning Drools from the manual, I have a question about Dynamic
Beans. I have added PropertyChangeSupport and listeners to my Beans: I can
see that inside my rule, if I change
one property the bean.....
rule "Check Age"
salience 20
when
b : Buyer (age <18)
then
bankApp.addMessage(Messages.AGE_UNDER_18);
b.setCash(40000); // CHANGE OF PROPERTY
end
..then all rules are fired back again. Is it the correct behaviour ? is
there a way to re-evaluate only some of the Rules back again ?
thanks a lot
Francesco
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4:24 a.m.
Hi Francesco,
On Wed, Jul 2, 2008 at 10:28 AM, fmarchioni <f.marchioni(a)pride.it> wrote:
Hi all drools users!
I'm just learning Drools from the manual, I have a question about Dynamic
Beans. I have added PropertyChangeSupport and listeners to my Beans: I can
see that inside my rule, if I change
one property the bean.....
rule "Check Age"
salience 20
when
b : Buyer (age <18)
then
bankApp.addMessage(Messages.AGE_UNDER_18);
b.setCash(40000); // CHANGE OF PROPERTY
end
..then all rules are fired back again. Is it the correct behaviour ? is
there a way to re-evaluate only some of the Rules back again ?
thanks a lot
Francesco
--
that's strange. From my experience, only those rules that depend on
the cash property should be fired if the new value triggers an
activation that wouldn't have been triggered for the old value. Could
you post the code of your PropertyChangeSupport implementation?
Here's some sample code from one of my projects:
public abstract class BindObject { /* simple proxy */
private PropertyChangeSupport propertyChangeSupport = new
PropertyChangeSupport(this);
public void addPropertyChangeListener(PropertyChangeListener _listener) {
propertyChangeSupport.addPropertyChangeListener(_listener);
}
public void addPropertyChangeListener(String _propertyName,
PropertyChangeListener _listener) {
propertyChangeSupport.addPropertyChangeListener(_propertyName,
_listener);
}
public void removePropertyChangeListener(PropertyChangeListener _listener) {
propertyChangeSupport.removePropertyChangeListener(_listener);
}
public void removePropertyChangeListener(String _propertyName,
PropertyChangeListener _listener) {
propertyChangeSupport.removePropertyChangeListener(_propertyName,
_listener);
}
protected void firePropertyChange(String _propertyName, Object
_oldValue, Object _newValue) {
propertyChangeSupport.firePropertyChange(_propertyName,
_oldValue, _newValue);
}
protected void firePropertyChange(String _propertyName, int
_oldValue, int _newValue) {
propertyChangeSupport.firePropertyChange(_propertyName,
_oldValue, _newValue);
}
protected void firePropertyChange(String _propertyName, boolean
_oldValue, boolean _newValue) {
propertyChangeSupport.firePropertyChange(_propertyName,
_oldValue, _newValue);
}
}
Now I simply inherit my classes from BindObject and write my setters like this:
public final static String PROPERTY_ARTICLE_NUMBER = "articleNumber";
public void setArticleNumber(String _articleNumber) {
String oldValue = _articleNumber;
articleNumber = _articleNumber;
firePropertyChange(PROPERTY_ARTICLE_NUMBER, oldValue, articleNumber);
}
This has been working great for me so far.
HTH
Marcus
7:38 a.m.
that's strange. From my experience, only those rules that depend
on
the cash property should be fired if the new value triggers an
activation that wouldn't have been triggered for the old value. Could
you post the code of your PropertyChangeSupport implementation?
Hi Marcus,
thanks for your reply, well my Bean implementation is:
public class Buyer {
int age;
double yearlyIncome;
double cash;
private final PropertyChangeSupport changes = new PropertyChangeSupport(
this );
public void addPropertyChangeListener(final PropertyChangeListener l) {
this.changes.addPropertyChangeListener( l );
}
public void removePropertyChangeListener(final PropertyChangeListener l) {
this.changes.removePropertyChangeListener( l );
}
public int getAge() {
return age;
}
public void setAge(int newAge) {
int oldAge = this.age;
this.age = newAge;
this.changes.firePropertyChange("age", oldAge, newAge);
}
public double getCash() {
return cash;
}
public void setCash(double newCash) {
double oldCash = this.cash;
this.cash = newCash;
System.out.println("[Buyer ] cash is " + this.cash);
this.changes.firePropertyChange("cash", oldCash, newCash);
}
public double getYearlyIncome() {
return yearlyIncome;
}
public void setYearlyIncome(double newYearlyIncome) {
double oldYearlyIncome = this.yearlyIncome;
this.yearlyIncome = newYearlyIncome;
this.changes.firePropertyChange("yearlyIncome", oldYearlyIncome,
newYearlyIncome);
}
}
And my complete Rule file is:
global drools.BankApplication bankApp;
rule "Check Age"
when
b : Buyer (age <18)
then
System.out.println("[Rule.drl] Checking age");
bankApp.addMessage(Messages.AGE_UNDER_18);
b.setCash(40000);
end
rule "Check Cash"
when
b : Buyer (cash <5000)
then
System.out.println("[Rule.drl] Checking cash");
System.out.println("[Rule.drl] cash is " + b.getCash());
bankApp.addMessage(Messages.CASH_LOW );
end
rule "Check Income"
when
b : Buyer (yearlyIncome <50000)
then
System.out.println("[Rule.drl] Checking income");
bankApp.addMessage(Messages.INCOME_LOW );
end
And facts are passed to the Working memory this way:
Buyer buyer = new Buyer();
BankApplication bankApp = new BankApplication();
buyer.setAge(15);
buyer.setCash(1000);
buyer.setYearlyIncome(30000);
workingMemory.setGlobal("bankApp", bankApp);
workingMemory.insert(buyer,true);
workingMemory.fireAllRules();
Looking at the log file:
14:23:47,109 INFO [STDOUT] [Buyer ] Setted cash with 1000.0
14:23:47,109 INFO [STDOUT] [Rule.drl] Checking income
14:23:47,125 INFO [STDOUT] [Rule.drl] Checking cash
14:23:47,125 INFO [STDOUT] [Rule.drl] cash is 1000.0
14:23:47,125 INFO [STDOUT] [Rule.drl] Checking age
14:23:47,125 INFO [STDOUT] [Buyer ] Setted cash with 40000.0
14:23:47,125 INFO [STDOUT] [Rule.drl] Checking income
14:23:47,125 INFO [STDOUT] [Rule.drl] Checking age
14:23:47,125 INFO [STDOUT] [Buyer ]Setted cash with 40000.0
I can see that the Rule "income" has been invoked twice: why if it doesn't
use the cash attribute in it ?
Thanks a lot for your time
Francesco
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2 comments
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participants (2)
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fmarchioni -
Marcus Ilgner