Thanks Ernest!
Please pardon my ignorace, but I am having some
difficulty with runUntilHalt(). When I execute the
code with 'run()' it works, but when I use
'runUntilHalt()' it does not work. Here's the code:
=====================================================
CurrentState.java
=====================================================
import java.beans.PropertyChangeListener;
import java.beans.PropertyChangeSupport;
public class CurrentState {
public static final int OFFLINE
= 0;
public static final int HANDLE_UP
= 1;
public static final int HANDLE_DOWN
= 2;
private static final int MAX_STATE_ID
= 3;
private int currentState;
private int previousState;
private PropertyChangeSupport pcs;
public CurrentState() {
pcs = new PropertyChangeSupport(this);
currentState = HANDLE_DOWN;
previousState = OFFLINE;
}
public void setCurrentState(int _state) {
System.out.println("CurrentState:
setCurrentState: passed integer is " + _state);
if ((_state > 0) && (_state <=
MAX_STATE_ID)) {
previousState = currentState;
currentState = _state;
pcs.firePropertyChange("CurrentState", new
Integer(previousState), new Integer(currentState));
}
}
public int getCurrentState() {
return currentState;
}
public void
addPropertyChangeListener(PropertyChangeListener _l) {
pcs.addPropertyChangeListener(_l);
}
public void
removePropertyChangeListener(PropertyChangeListener
_l) {
pcs.removePropertyChangeListener(_l);
}
}
=====================================================
testJess.java
=====================================================
import jess.*;
import java.util.*;
public class testJess
{
private Rete rete;
private Context c;
public testJess() {
rete = new Rete();
c = rete.getGlobalContext();
}
public static void main(String[] argv) {
testJess tj = new testJess();
tj.test();
}
public void test() {
try {
// Read in packages
rete.addUserpackage(new PredFunctions());
rete.addUserpackage(new MiscFunctions());
// Read files
System.out.println("Reading batch files:
scriptlib.clp, test.clp.");
rete.executeCommand("(batch scriptlib.clp)");
rete.executeCommand("(batch test.clp)");
rete.reset();
// Launch a separate thread that runs forever
until the halt is encountered
/*
Thread thr = new Thread() {
public void run() {
this.yield();
try {
testJess.this.rete.runUntilHalt();
} catch (JessException e) {
e.printStackTrace();
}
}
};
thr.start();
System.out.println("Thread started with
(run-until-halt)");
*/
// Assert handle-up
System.out.println("Asserting fact
'handle-up'...");
Fact f = ((Value) rete.executeCommand("(assert
(handle-up))")).factValue(c);
System.out.println("Facts after the asserting
'handle-up'");
listFacts(rete);
rete.executeCommand("(run)");
// Get Current State
CurrentState cs = (CurrentState)
rete.getGlobalContext().getVariable("*cState*").externalAddressValue(c);
System.out.println("Retrieved CurrentState
object from JESS, current state = " +
cs.getCurrentState());
listFacts(rete);
// Retract handle-up
int id = f.getFactId();
System.out.println("Retracting 'handle-up'");
rete.executeCommand("(retract (fact-id " + id
+ "))");
System.out.println("Facts after the retract");
listFacts(rete);
// Set current state to 1
cs.setCurrentState(1);
System.out.println("Set currentState = 1 from
the reference to the Java object");
// Assert handle-up again
System.out.println("Asserting fact
'handle-up'...");
Fact fact = ((Value)
rete.executeCommand("(assert
(handle-up))")).factValue(c);
System.out.println("Facts after the asserting
'handle-up'");
listFacts(rete);
rete.executeCommand("(run)");
// Get Current State again
cs = (CurrentState)
rete.getGlobalContext().getVariable("*cState*").externalAddressValue(c);
System.out.println("Retrieved CurrentState
object from JESS, current state = " +
cs.getCurrentState());
listFacts(rete);
// Retract handle-up again
int fid = fact.getFactId();
System.out.println("Retracting 'handle-up'");
rete.executeCommand("(retract (fact-id " + fid
+ "))");
System.out.println("Facts after the retract");
listFacts(rete);
if (1 == 1) {
System.out.println("");
System.out.println("Issuing
'stop-exec'");
rete.executeCommand("(assert
(stop-exec))");
}
} catch (JessException re) {
re.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
}
public static void listFacts(Rete _rete) {
System.out.println("");
System.out.println("Listing
facts...");
for (Enumeration e =
_rete.listFacts(); e.hasMoreElements();) {
Object t = e.nextElement();
System.out.println(t.toString());
}
}
}
=====================================================
test.clp
=====================================================
(watch all)
(set-reset-globals nil)
(defglobal ?*cState* = (new CurrentState))
(defrule handle-up-rule
(handle-up)
=>
(printout t "Executing handle-up-rule..." crlf)
(call ?*cState* setCurrentState 2)
)
(defrule end-exec
(stop-exec)
=>
(halt)
)
=====================================================
Output
=====================================================
Reading batch files: scriptlib.clp, test.clp.
handle-up-rule: +1+1+1+t
end-exec: +1+1+1+t
==> f-0 (initial-fact)
Asserting fact 'handle-up'...
==> f-1 (handle-up)
==> Activation: handle-up-rule : f-1
Facts after the asserting 'handle-up'
Listing facts...
(initial-fact)
(handle-up)
FIRE 1 handle-up-rule f-1
Executing handle-up-rule...
CurrentState: setCurrentState: passed integer is 2
Retrieved CurrentState object from JESS, current state
= 2
Listing facts...
(initial-fact)
(handle-up)
Retracting 'handle-up'
<== f-1 (handle-up)
Facts after the retract
Listing facts...
(initial-fact)
CurrentState: setCurrentState: passed integer is 1
Set currentState = 1 from the reference to the Java
object
Asserting fact 'handle-up'...
==> f-2 (handle-up)
==> Activation: handle-up-rule : f-2
Facts after the asserting 'handle-up'
Listing facts...
(initial-fact)
(handle-up)
FIRE 1 handle-up-rule f-2
Executing handle-up-rule...
CurrentState: setCurrentState: passed integer is 2
Retrieved CurrentState object from JESS, current state
= 2
Listing facts...
(initial-fact)
(handle-up)
Retracting 'handle-up'
<== f-2 (handle-up)
Facts after the retract
Listing facts...
(initial-fact)
Issuing 'stop-exec'
==> f-3 (stop-exec)
==> Activation: end-exec : f-3
=====================================================
My Question:
=====================================================
Why does this code not work when I replace the
multiple 'run()' commands with the currently commented
out section that starts a separate Thread. This Thread
calls the 'runUntilHalt()' function. When run with the
separate Thread, the 'CurrentState' never changes (see
setCurrentState() method). However, it does execute
the 'end-exec' rule! (??)
=====================================================
Output with Thread (runUntilHalt()) instead of
multiple run() commands
=====================================================
Reading batch files: scriptlib.clp, test.clp.
handle-up-rule: +1+1+1+t
end-exec: +1+1+1+t
==> f-0 (initial-fact)
Thread started with (run-until-halt)
Asserting fact 'handle-up'...
==> f-1 (handle-up)
==> Activation: handle-up-rule : f-1
Facts after the asserting 'handle-up'
Listing facts...
(initial-fact)
(handle-up)
Retrieved CurrentState object from JESS, current state
= 3
Listing facts...
(initial-fact)
FIRE 1 handle-up-rule f-1
(handle-up)
Executing handle-up-rule...
CurrentState: setCurrentState: passed integer is 2
Retracting 'handle-up'
<== f-1 (handle-up)
<== Activation: handle-up-rule : f-1
Facts after the retract
Listing facts...
(initial-fact)
CurrentState: setCurrentState: passed integer is 1
Set currentState = 1 from the reference to the Java
object
Asserting fact 'handle-up'...
==> f-2 (handle-up)
==> Activation: handle-up-rule : f-2
Facts after the asserting 'handle-up'
Listing facts...
(initial-fact)
(handle-up)
Retrieved CurrentState object from JESS, current state
= 1
Listing facts...
(initial-fact)
(handle-up)
Retracting 'handle-up'
<== f-2 (handle-up)
<== Activation: handle-up-rule : f-2
Facts after the retract
Listing facts...
(initial-fact)
Issuing 'stop-exec'
==> f-3 (stop-exec)
==> Activation: end-exec : f-3
FIRE 2 end-exec f-3
=====================================================
Any help is greatly appreciated!!!!!!!!!!!!!!!!
Thanks,
- Ashish
--- friedman_hill ernest j
<[EMAIL PROTECTED]> wrote:
> I think Ashish Majmundar wrote:
> > Hi,
> >
> >
> > Rete rete = new Rete();
> > Context c = rete.getGlobalContext();
> > rete.executeCommand("(reset)");
> ....
> > rete.reset();
>
>
> These last two calls have -exactly- the same effect,
> but the first one
> is inefficient.
>
> > rete.executeCommand("(batch test.clp)");
> ....
> > rete.executeCommand("(assert
> (run-until-halt))");
>
> This is the problem.
>
> 1) Here you've confused executing a function with
> asserting a
> fact. (run-until-halt) is a function; what you've
> done here is assert
> a fact (run-until-halt) which, despite the similar
> apeparance, is
> absolutely unrelated to what you want to do.
>
> 2) The function you meant to call, (run-until-halt),
> does not return
> until (halt) is called - i.e., the below code will
> never be
> executed. If you want to call (run-until-halt) and
> then make more Java
> calls from the same method, you need to make the
> (run-until-halt) call
> in a separate Thread.
>
>
> >
> ===================================================
> > test.clp
> >
> ===================================================
> > (set-reset-globals nil)
>
> You've got no global variables in this program, so
> this has no effect.
>
> > My question is: why doesn't the 'Current State
> after
> > assert on handle-up' say 'handle-up'?
> >
> > Thanks in advance.
>
>
> The rest of your code is correct, as far as I can
> see. It generally
> helps when developing this sort of code to 1) Get
> the Jess code
> working by itself, first, interactively. Only when
> it does what you
> expect should you then embed it in a Java
> application. 2) use the Jess
> command (watch all) so that the engine tells you
> what it's doing; this
> would have let you know that your rules were never
> firing because no
> form of (run) was being called.
>
>
>
>
>
---------------------------------------------------------
> Ernest Friedman-Hill
> Distributed Systems Research Phone: (925)
> 294-2154
> Sandia National Labs FAX: (925)
> 294-2234
> Org. 8920, MS 9012
> [EMAIL PROTECTED]
> PO Box 969
> http://herzberg.ca.sandia.gov
> Livermore, CA 94550
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