1. Integration Part 2 csandru@info.uvt.ro
Intelligent Systems
Integration Part 2

2. Shadow facts Unordered facts that serve as "bridges" to Java objects
Serve to put any Java object into Jess's working memory.
(deftemplate account (declare (from-class Account))) - construct
(defclass account Account) – function
(definstance account (new Account “Name”) [static | dynamic | auto] )
(assert (Account (name “Test”))): no object created
(add new Account “Other”): automatically creates a template called “Account”, a shadow fact and the account object
(bind ?a (new Account “Third”))
(add ?a)
Jess> (facts)
f-0 (MAIN::Account (balance 0.0) (class <Java-Object:java.lang.Class>) (OBJECT <Java-Object:Account>))

3. Ensuring shadow facts consistency
(bind ?pObject (new Person “John” “B”))
(bind ?person (add ?pObject))
(modify ?person (name “Jack”)): pObject automatically updated
(?pObject setName “Jack”): fact is not updated; need special update
(update ?pObject)

4. Automatic updating public class Person {
PropertyChangeSupport pcs = new PropertyChangeSupport(this);
public void setName(String name) {
String temp = name;
this.name = name;
pcs.firePropertyChange("name", temp, name); }
public void setBlood(String blood) {
String temp = blood;
this.blood = blood;
pcs.firePropertyChange("blood", temp, blood); };
public void addPropertyChangeListener(PropertyChangeListener pcl) {
pcs.addPropertyChangeListener(pcl);
public void removePropertyChangeListener(PropertyChangeListener pcl) {
pcs.removePropertyChangeListener(pcl);

5. Querying WM
Allows for retrieving working memory objects/facts based on filters
Iterator<Object> it = expertEngine.getObjects(new Filter() {
public boolean accept(Object o) {
return o instanceof Person; }
});
while(it.hasNext()) {
System.out.println("Person object in WM: " + ((Person) it.next()).getName());

6. Queries Defining queries Collect the result (defquery search-by-name
"Finds compatibilities for a given name"
(declare (variables ?name))
(compatibility (who ?name) (with ?with&~”John”)) )
Collect the result
QueryResult result = expertEngine.runQueryStar("search-by-name", new ValueVector().add(new Value(“Mathew”, RU.STRING)));
while (result.next()) {
System.out.println(name + " is compatible with: " + result.getString("with")); }

7. Marks in the working memory
Save a working memory status
expertEngine.batch("bgExpert.clp");
expertEngine.reset();
expertEngine.addAll(getDonors());
//save this engine status for future resets
WorkingMemoryMarker initialStatus = expertEngine.mark();
Reset to saved status
expertEngine.resetToMark(initialStatus);

8. Java from Jess Source: awtdraw.clp (import java.awt.event.WindowEvent)
(import java.awt.event.WindowListener)
(import java.awt.Frame)
(import java.awt.Color)
(deffunction create-components ()
(bind ?f (new Frame "Drawing Demo"))
(?f addWindowListener
(implement WindowListener using (lambda (?name?event)
(if (eq ?name windowClosing) then
(System.exit 0)))))
(bind ?c (new jess.awt.Canvas painter (engine)))
(?f add "Center" ?c)
(?f setSize )
(?f setVisible TRUE))

9. Adding commands to Jess
public class ExMyUpcase implements Userfunction { // The name method returns the name by which // the function will appear in Jess code.
public String getName() {
return "my-upcase"; }
public Value call(ValueVector vv, Context context) throws JessException {
String result = vv.get(1).stringValue(context).toUpperCase(); return new Value(result, RU.STRING);
r.addUserfunction(new ExMyUpcase());

10. Blood Groups Sample Adapted
Loading persons from JAVA while keeping blood rules in JESS
(deftemplate Person
(declare (from-class Person)) )
private List<Person> getDonors(){
List<Person> donors = new ArrayList<Person>();
donors.add(new Person("John", "O"));
donors.add(new Person("Stan", "O"));
donors.add(new Person("Peter", "A"));
donors.add(new Person("Bruce", "B"));
donors.add(new Person("Dan", "AB"));
donors.add(new Person("Mathew", "A"));
donors.add(new Person("Andrew", "B"));
return donors; }
expertEngine.addAll(getDonors());

11. JESS side elements (defrule transfusion =>
(need-transfusion (who ?who))
(Person (name ?who) (blood ?required))
(Person (name ?source&~?who) (blood ?bg))
(blood-acceptance (acceptor ?required) (donators $? ?bg $?))
=>
(assert (compatibility (who ?who) (with ?source))) )
(defquery search-by-name
"Finds compatibilities for a given name"
(declare (variables ?name))
(compatibility (who ?name) (with ?with))

12. JAVA side elements
//create a person object and make it available in the expertise
Person personNeedingBlood = new Person(name, bg);
expertEngine.add(personNeedingBlood);
//create the needed transfusion fact and assert it
String factStr = "(need-transfusion (who \"" + name + "\"))";
expertEngine.assertString(factStr);
//collect the result
QueryResult result = expertEngine.runQueryStar("search-by-name", new ValueVector().add(new Value(name, RU.STRING)));
while (result.next()) {
System.out.println(name + " is compatible with: " + result.getString("with")); }