[rules-users] Trouble with insertlogical

[XIAOTAO]

Hi,

i modified the shopping example from drool 4.0.4 example downloaded from jboss website in order to have a better understanding of insertlogical.

the rule is as follows

package org.drools.examples

dialect "mvel"

import org.drools.examples.ShoppingExample.Customer
import org.drools.examples.ShoppingExample.Product
import org.drools.examples.ShoppingExample.Purchase
import org.drools.examples.ShoppingExample.Discount

rule "Purchase notification"
    salience 10

	when
		$c : Customer()
		$p : Purchase( customer == $c)	    
	then
	    System.out.println( "Customer " + $c.name + " just purchased " + $p.product.name );
end	 

rule "Discount removed notification"
	when
	    $c : Customer()
		not Discount( customer == $c )
	then
		$c.discount = 0 ;
		System.out.println( "Customer " + $c.name + " now has a discount of " + $c.discount );
end

rule "Discount awarded notification"
	when
	    $c : Customer()
		$d : Discount( customer == $c )
	then
		System.out.println( "Customer " + $c.name + " now has a discount of " + $d.amount );
end

rule "Apply 10% discount if total purcahses is over 100"			
	no-loop true
	dialect "java"
    when
		$c : Customer()
		$i : Double(doubleValue > 100) from accumulate ( Purchase( customer == $c, $price : product.price ), 
		                                                            sum( $price ) )
    then
  		$c.setDiscount( 10 );
		insertLogical( new Discount($c, 10) );	
		System.out.println( "Customer " + $c.getName() + " now has a shopping total of " + $i );
end




my java lanucher

package org.drools.examples;

import java.io.InputStreamReader;

import org.drools.FactHandle;
import org.drools.RuleBase;
import org.drools.RuleBaseFactory;
import org.drools.StatefulSession;
import org.drools.audit.WorkingMemoryFileLogger;
import org.drools.compiler.PackageBuilder;

public class ShoppingExample {

    public static final void main(String[] args) throws Exception {
        final PackageBuilder builder = new PackageBuilder();
        builder.addPackageFromDrl( new InputStreamReader( ShoppingExample.class.getResourceAsStream( "Shopping.drl" ) ) );

        final RuleBase ruleBase = RuleBaseFactory.newRuleBase();
        ruleBase.addPackage( builder.getPackage() );

        final StatefulSession session = ruleBase.newStatefulSession();
        
        final WorkingMemoryFileLogger logger = new WorkingMemoryFileLogger( session );
        logger.setFileName( "log/shoppingExample" );

        Customer mark = new Customer( "mark",
                                      0 );
        session.insert( mark );

        Product shoes = new Product( "shoes",
                                     900 );
        session.insert( shoes );

        Product hat = new Product( "hat",
                                   160 );
        session.insert( hat );

        session.insert( new Purchase( mark,
                                      shoes ) );
        session.insert( new Purchase( mark,
                                        hat ) );
        session.fireAllRules();
        
        Product pent = new Product("pent", 100);
        session.insert(new Purchase(mark, pent));

        System.out.println( "Customer mark also buy the pent" );
        session.fireAllRules();
        
        logger.writeToDisk();
    }
    
    public static class Customer {
        private String name;
        
        private int discount;
            
        public Customer(String name,
                        int discount) {
            this.name = name;
            this.discount = discount;
        }

        public String getName() {
            return name;
        }

        public int getDiscount() {
            return discount;
        }

        public void setDiscount(int discount) {
            this.discount = discount;
        }
                       
    }
    
    public static class Discount {
        private Customer customer;
        private int amount;

        public Discount(Customer customer,
                        int amount) {
            this.customer = customer;
            this.amount = amount;
        }    
        
        public Customer getCustomer() {
            return customer;
        }

        public int getAmount() {
            return amount;
        }
        
    }

    public static class Product {
        private String name;
        private float price;
        
        public Product(String name,
                       float price) {
            this.name = name;
            this.price = price;
        }
        
        public String getName() {
            return name;
        }
        
        public float getPrice() {
            return price;
        }
        
        
    }
    
    public static class Purchase {
        private Customer customer;
        private Product product;
        
        public Purchase(Customer customer,
                        Product product) {
            this.customer = customer;
            this.product = product;
        }
        
        public Customer getCustomer() {
            return customer;
        }
        
        public Product getProduct() {
            return product;
        }            
    }    
}


i got the following output after i ran the java code
Customer mark just purchased hat
Customer mark just purchased shoes
Customer mark now has a shopping total of 1060.0
Customer mark now has a discount of 10
Customer mark also buy the pent
Customer mark just purchased pent
Customer mark now has a discount of 0
Customer mark now has a shopping total of 1160.0
Customer mark now has a discount of 10

i don not know why  "Customer mark now has a discount of 0" still get printed. As my understanding, the insertion of the pent purchase should still keep the  "Apply 10% discount if total purcahses is over 100" rule valid, so the logical Discount is not retracted which means that the engine should not print out the "
Customer mark now has a discount of 0". However i got the opposite answer.

is my understanding wrong or i miss something ?

I am running drools 4.0.4

Thanks for any help

Regards,
Tao

_________________________________________________________________
MSN圣诞礼物火热登场，免费发放中，快来领取吧！
http://im.live.cn/emoticons/?ID=18