I discovered the same issue. Once you call definstance for an object, reset
will update the Jess fact with the Java object, but does not remove it.
I created the following two methods in my Java program to both add and
remove objects, where a corresponding defclass is in the ruleset. Similar
to you, I used these to take results of a database query and assert them
into Jess.
public void undefinstance( Rete rete, Object fact ) {
try {
// Create the ValueVector (undefinstance <this>)
ValueVector vv = new ValueVector(2);
vv.set( new Value(("definstance"), RU.STRING), 0 );
vv.set( new Value(fact, RU.EXTERNAL_ADDRESS), 1 );
Userfunction undefinst = rete.findUserfunction("undefinstance");
undefinst.call(vv, rete.globalContext());
} catch (ReteException re) {
re.printStackTrace(System.out);
}
}
public void definstance( Rete rete, Object fact ) {
try {
// Create the ValueVector (definstance Foo <this>)
ValueVector vv = new ValueVector(3);
vv.set( new Value(("definstance"), RU.STRING), 0 );
vv.set( new Value(fact.getClassName(), RU.STRING), 1 );
vv.set( new Value(fact, RU.EXTERNAL_ADDRESS), 2 );
Userfunction definst = rete.findUserfunction("definstance");
definst.call(vv, rete.globalContext());
} catch (ReteException re) {
re.printStackTrace(System.out);
}
}
At 12:00 PM 10/21/98 -0500, you wrote:
>I've created a loop in which I read a record from an oracle database,
>create a java bean class, set a variable (which has been defclass'd
>within a jess file). Then I call reset, Funcall (to call the
>definstance
>function to pass in the object), then call run.
>
>My question is: am I using the reset properly? I thought that by
>calling reset, it would erase the previous definstance, so that the
>engine would run only on the current definstance. I put in a (watch
>all),
>and it is showing that I'm collecting all the instances, and the engine
>is firing upon them all each time I call run.
>
>Is there some other way I'm supposed to delete the definstances?
>
>Thanks for any help,
>
>KathyLee Simunich
>Decision & Information Sciences Division
>Argonne National Lab
>
>----code segment follows-----
>
> for (int i= 0; i < numrecs; i++) {
> ccc = (String)fieldReturns[0].get(i); // field from oracle
>db
>
> // create the bean
> tRec = new TRecord();
> tRec.setCCC(ccc);
>
> // assert the facts, and execute manually.
> try {
> rete.executeCommand("(reset)");
>
> // Tell Jess about the bean
> Funcall f = new Funcall("definstance", rete);
> f.add(new Value("tRec", RU.ATOM));
> f.add(new Value(tRec, RU.EXTERNAL_ADDRESS));
> f.simpleExecute(f, rete.globalContext());
>
> // now run on the new definstance
> rete.executeCommand("(run)");
> } catch (ReteException re) {
> re.printStackTrace(nd.stderr());
> }
> }
>
>
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