Drools problem
Hi All,
I am new in drools engine.
I am facing one error. I am using drools 4.0.4. I am also attaching the files for your easy reference.
Error is :
org.drools.RuntimeDroolsException: java.lang.NullPointerException
at org.drools.rule.EvalCondition.isAllowed(EvalCondition.java:76)
at org.drools.reteoo.EvalConditionNode.assertTuple(EvalConditionNode.java:145)
at org.drools.reteoo.CompositeTupleSinkAdapter.createAndPropagateAssertTuple(CompositeTupleSinkAdapter.java:73)
at org.drools.reteoo.LeftInputAdapterNode.assertObject(LeftInputAdapterNode.java:116)
at org.drools.reteoo.SingleObjectSinkAdapter.propagateAssertObject(SingleObjectSinkAdapter.java:22)
at org.drools.reteoo.ObjectTypeNode.assertObject(ObjectTypeNode.java:153)
at org.drools.reteoo.Rete.assertObject(Rete.java:175)
at org.drools.reteoo.ReteooRuleBase.assertObject(ReteooRuleBase.java:192)
at org.drools.reteoo.ReteooWorkingMemory$WorkingMemoryReteAssertAction.execute(ReteooWorkingMemory.java:179)
at org.drools.common.AbstractWorkingMemory.executeQueuedActions(AbstractWorkingMemory.java:1315)
at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:914)
at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:881)
at org.drools.common.AbstractWorkingMemory.insert(AbstractWorkingMemory.java:682)
at com.sample.BusinessLayer.evaluateStockPurchase(BusinessLayer.java:111)
at com.sample.BusinessRuleTest.testStockBuy(BusinessRuleTest.java:30)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at junit.framework.TestCase.runTest(TestCase.java:154)
at junit.framework.TestCase.runBare(TestCase.java:127)
at junit.framework.TestResult$1.protect(TestResult.java:106)
at junit.framework.TestResult.runProtected(TestResult.java:124)
at junit.framework.TestResult.run(TestResult.java:109)
at junit.framework.TestCase.run(TestCase.java:118)
at junit.framework.TestSuite.runTest(TestSuite.java:208)
at junit.framework.TestSuite.run(TestSuite.java:203)
at org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:128)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)
Caused by: java.lang.NullPointerException
at com.sample.Rule_XYZCorp_0.eval0(Rule_XYZCorp_0.java:12)
at com.sample.Rule_XYZCorp_0Eval0Invoker.evaluate(Rule_XYZCorp_0Eval0Invoker.java:16)
at org.drools.rule.EvalCondition.isAllowed(EvalCondition.java:72)
... 32 more
The files are:
#created on: Mar 27, 2008
package com.sample
#list any import classes here.
import com.sample.StockOffer;
import com.sample.DaoFactory;
import com.sample.StockNameDao;
import java.lang.Object;
import java.lang.String;
#declare any global variables here
global DaoFactory daoFactory;
global StockOffer stockOffer;
rule "XYZCorp"
salience -1
when
#conditions
//eval(stockOffer.getStockName().equals("XYZ") )and
//eval(stockOffer.getRecommendPurchase() == null )and
//eval(stockOffer.getStockPrice() > 10)
eval((stockOffer.getStockName().equals("XYZ")) && (stockOffer.getRecommendPurchase() == null) && (stockOffer.getStockPrice() > 10))
then
#actions
stockOffer.setRecommendPurchase(StockOffer.NO);
System.out.println("Name:"+stockOffer.getStockName()+" Price: "+stockOffer.getStockPrice() +" BUY:"+stockOffer.getRecommendPurchase());
end
rule "Stock Price Not Negative"
#include attributes such as "salience" here...
when
#conditions
eval (stockOffer.getStockPrice() < 0 )
then
#actions
stockOffer.setRecommendPurchase(StockOffer.NO);
System.out.println("Name:"+stockOffer.getStockName()+" Price: "+stockOffer.getStockPrice() +" BUY:"+stockOffer.getRecommendPurchase());
end
rule "Stock Price Low Enough"
#include attributes such as "salience" here...
when
#conditions
//eval(daoFactory.getStockDao().isOnStockList(stockOffer.getStockName())) and
//eval(stockOffer.getRecommendPurchase() == null )and
//eval(stockOffer.getStockPrice() < 100)
eval((daoFactory.getStockDao().isOnStockList(stockOffer.getStockName())) && (stockOffer.getRecommendPurchase() == null) && (stockOffer.getStockPrice() < 100))
then
#actions
stockOffer.setRecommendPurchase(StockOffer.YES);
System.out.println("Name:"+stockOffer.getStockName()+" Price: "+stockOffer.getStockPrice() +" BUY:"+stockOffer.getRecommendPurchase());
end
and BusinessLayer.java:
package com.sample;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
//import org.drools.DroolsException;
import org.drools.RuleBase;
import org.drools.RuleBaseFactory;
import org.drools.WorkingMemory;
import org.drools.event.DebugWorkingMemoryEventListener;
//import org.drools.io.RuleBaseLoader;
import org.xml.sax.SAXException;
import org.drools.rule.Package;
import org.drools.spi.ConflictResolver;
import org.drools.compiler.PackageBuilder;
import org.drools.conflict.SalienceConflictResolver;
import org.drools.conflict.FifoConflictResolver;
import org.drools.conflict.CompositeConflictResolver;
import org.drools.conflict.SimplicityConflictResolver;
import org.drools.conflict.RecencyConflictResolver;
import org.drools.conflict.LoadOrderConflictResolver;
/**
* Facade for the Business Logic in our example.
*
* In this simple example , all our business logic is contained in this class
* but in reality it would delegate to other classes as required.
* @author Paul Browne - www.firstpartners.net
*/
public class BusinessLayer {
//Name of the file containing the rules
//private static final String BUSINESS_RULE_FILE="BusinessRules.drl";
//private static final String BUSINESS_RULE_FILE="C:/MyEclipse_JRE/DroolsTest2/src/main/rules/BusinessRules.drl";
//Internal handle to rule base
private static RuleBase businessRules = null;
/**
* Load the business rules if we have not already done so
* @throws Exception - normally we try to recover from these
*/
private static void loadRules() throws Exception{
if (businessRules==null){
System.out.println("Mukesh 5");
//Generate our list of conflict resolvers
/* ConflictResolver[] conflictResolvers =
new ConflictResolver[] { SalienceConflictResolver.getInstance( ),
RecencyConflictResolver.getInstance(),
SimplicityConflictResolver.getInstance( ),
LoadOrderConflictResolver.getInstance( )};
//Wrap this up into one composite resolver
CompositeConflictResolver resolver = new CompositeConflictResolver(conflictResolvers);
*/
//Specify this resolver when we load are rules
//businessRules = RuleBaseLoader.loadFromUrl(
// BusinessLayer.class.getResource( BUSINESS_RULE_FILE )/*,resolver*/ );
Reader source = new InputStreamReader( BusinessLayer.class.getResourceAsStream( "/BusinessRules.drl") );
final PackageBuilder builder = new PackageBuilder();
System.out.println("Mukesh 6 ");
//builder.addPackageFromDrl(new InputStreamReader(new FileInputStream(BUSINESS_RULE_FILE)));
//builder.addPackageFromXml(new InputStreamReader(new FileInputStream(BUSINESS_RULE_FILE)));
builder.addPackageFromDrl(source);
System.out.println("Mukesh 7");
Package pkg = builder.getPackage();
System.out.println("Mukesh 8");
businessRules = RuleBaseFactory.newRuleBase();
businessRules.addPackage( pkg );
System.out.println("Mukesh 9");
}
}
/**
* Evaluate whether or not it is a good idea to purchase this stock.
* @param stockToBuy
* @return true if the recommendation is to buy the stock , false if otherwise
* @throws Exception - normally we try to recover from these
*/
public static void evaluateStockPurchase(StockOffer stockToBuy) throws Exception{
System.out.println("Mukesh 3");
//Ensure that the business rules have been loaded
loadRules();
System.out.println("Mukesh 4");
//Some logging of what is going on
System.out.println( "\n\n\n\nFIRE RULES" );
System.out.println( "----------" );
//Clear any state from previous runs of the business engine
// WorkingMemory workingMemory = businessRules.newWorkingMemory( );
WorkingMemory workingMemory = businessRules.newStatefulSession();
System.out.println("Mukesh 10");
DaoFactory daoFactory = new DaoFactory();
System.out.println("Mukesh 11");
StockOffer stockOffer = new StockOffer();
System.out.println("Mukesh 12");
workingMemory.setGlobal("daoFactory", daoFactory);
System.out.println("Mukesh 13");
workingMemory.setGlobal("stockOffer", stockOffer);
System.out.println("Mukesh 14");
//This is a small ruleset , so we can add a debug listener to see what is going on
workingMemory.insert(stockToBuy);
//workingMemory.insert(stockOffer);
System.out.println("Mukesh 15");
workingMemory.addEventListener(
new DebugWorkingMemoryEventListener( ) );
System.out.println("Mukesh 16");
//Let the rule engine know about the facts
// workingMemory.assertObject(stockToBuy);
//workingMemory.insert(stockToBuy);
System.out.println("Mukesh 17");
//Let the rule engine do it's stuff!!
workingMemory.fireAllRules( );
System.out.println("Mukesh 18");
}
}
and
BusinessRuleTest:
package com.sample;
import junit.framework.TestCase;
public class BusinessRuleTest extends TestCase {
/**
* Tests the purchase of a stock
*/
public void testStockBuy() throws Exception{
//Create a Stock with our simulated values
StockOffer testOffer = new StockOffer();
testOffer.setStockName("MEGACORP");
testOffer.setStockPrice(22);
testOffer.setStockQuantity(1000);
System.out.println("Mukesh 1");
//Run the rules on it
BusinessLayer.evaluateStockPurchase(testOffer);
System.out.println("Mukesh 2");
//Is it what we expected?
assertTrue(testOffer.getRecommendPurchase()!=null);
assertTrue("YES".equals(testOffer.getRecommendPurchase()));
}
/**
* Tests the purchase of a stock - makes sure the system
* will not accept negative numbers
*/
public void xtestNegativeStockBuy() throws Exception{
//Create a Stock with our simulated values
StockOffer testOffer = new StockOffer();
testOffer.setStockName("MEGACORP");
testOffer.setStockPrice(-22);
testOffer.setStockQuantity(1000);
//Run the rules on it
BusinessLayer.evaluateStockPurchase(testOffer);
//Is it what we expected?
assertTrue("NO".equals(testOffer.getRecommendPurchase()));
}
/**
* Makes sure the system will buy stocks of XYZ corp only if it really cheap
*/
public void xtestXYZStockBuy() throws Exception{
//Create a Stock with our simulated values
StockOffer testOfferLow = new StockOffer();
StockOffer testOfferHigh = new StockOffer();
testOfferLow.setStockName("XYZ");
testOfferLow.setStockPrice(9);
testOfferLow.setStockQuantity(1000);
testOfferHigh.setStockName("XYZ");
testOfferHigh.setStockPrice(11);
testOfferHigh.setStockQuantity(1000);
//Run the rules on it and test
BusinessLayer.evaluateStockPurchase(testOfferLow);
assertTrue("YES".equals(testOfferLow.getRecommendPurchase()));
BusinessLayer.evaluateStockPurchase(testOfferHigh);
assertTrue("NO".equals(testOfferHigh.getRecommendPurchase()));
}
}
and
DaoFactory.java
package com.sample;
public class DaoFactory {
public DaoFactory(){}
public static StockNameDao getStockDao(){
return new DaoImplementation();
}
}
and DaoImplementation.java
package com.sample;
public class DaoImplementation implements StockNameDao {
DaoImplementation(){
}
public String[] getStockNames() {
String[] stockNames={"XYZ","ABC","MEGACORP","SOMEOTHERCOMPANY"};
return stockNames;
}
public boolean isOnStockList(String stockName){
//Get our list of stocks
String stockList[] = getStockNames();
//Loop and see if our stock is on it
// done this way for clarity . not speed!
for (int a=0; a<stockList.length;a++){
if(stockList[a].equals(stockName)){
return true;
}
}
//Default returh value
return false;
}
}
and
StockDaoTest.java
package com.sample;
import junit.framework.TestCase;
public class StockDaoTest extends TestCase {
public void testIsOnStockList(){
StockNameDao myDao = DaoFactory.getStockDao();
assertTrue(myDao.isOnStockList("XYZ"));
}
}
StockNameDao.java
package com.sample;
public interface StockNameDao {
public String [] getStockNames();
public boolean isOnStockList(String stockName);
}
and
StockOffer.java
package com.sample;
public class StockOffer {
//constants
public final static String YES="YES";
public final static String NO="NO";
//Internal Variables
private String stockName =null;
private int stockPrice=0;
private int stockQuantity=0;
private String recommendPurchase = null;
public StockOffer (){}
/**
* @return Returns the stockName.
*/
public String getStockName() {
return stockName;
}
/**
* @param stockName The stockName to set.
*/
public void setStockName(String stockName) {
this.stockName = stockName;
}
/**
* @return Returns the stockPrice.
*/
public int getStockPrice() {
return stockPrice;
}
/**
* @param stockPrice The stockPrice to set.
*/
public void setStockPrice(int stockPrice) {
this.stockPrice = stockPrice;
}
/**
* @return Returns the stockQuantity.
*/
public int getStockQuantity() {
return stockQuantity;
}
/**
* @param stockQuantity The stockQuantity to set.
*/
public void setStockQuantity(int stockQuantity) {
this.stockQuantity = stockQuantity;
}
/**
* @return Returns the recommendPurchase.
*/
public String getRecommendPurchase() {
return recommendPurchase;
}
/**
* @param recommendPurchase The recommendPurchase to set.
*/
public void setRecommendPurchase(String recommendPurchase) {
this.recommendPurchase = recommendPurchase;
}
}
As per my understanding, problem is in BusinessRules.drl file itself.
Please help me if anyone has faced this issue.
Thanks and Regards,
Mukesh Anand Chaurasia
9811908986