BAEL-803: Backward Chaining with Drools - changefix (#3020)

drools/backward-chaining/pom.xml

@@ -1,35 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
-	<modelVersion>4.0.0</modelVersion>
-
-	<artifactId>drools-backward-chaining</artifactId>
-	<version>1.0</version>
-	<name>drools-backward-chaining</name>
-
-	<parent>
-		<groupId>com.baeldung</groupId>
-		<artifactId>parent-modules</artifactId>
-		<version>1.0.0-SNAPSHOT</version>
-	</parent>
-
-	<properties>
-		<runtime.version>6.4.0.Final</runtime.version>
-	</properties>
-	<dependencies>
-		<dependency>
-			<groupId>org.kie</groupId>
-			<artifactId>kie-api</artifactId>
-			<version>${runtime.version}</version>
-		</dependency>
-		<dependency>
-			<groupId>org.drools</groupId>
-			<version>${runtime.version}</version>
-		</dependency>
-		<dependency>
-			<groupId>org.drools</groupId>
-			<artifactId>drools-decisiontables</artifactId>
-			<version>${runtime.version}</version>
-		</dependency>
-	</dependencies>
-</project>

drools/backward-chaining/src/main/java/com/baeldung/BackwardChainingBeatles.java

@@ -1,28 +0,0 @@
-package com.baeldung;
-
-import org.kie.api.KieServices;
-import org.kie.api.runtime.KieContainer;
-import org.kie.api.runtime.KieSession;
-
-import com.baeldung.model.Beatle;
-
-public class BackwardChainingBeatles {
-    public static void main(String[] args) {
-        
-            KieServices ks = KieServices.Factory.get();
-            KieContainer kContainer = ks.getKieClasspathContainer();
-            KieSession kSession = kContainer.newKieSession("ksession-backward-chaining");
-            // drools session base on the xml configuration (<strong>kmodule.xml</strong>)
-
-            // graph population
-            kSession.insert(new Beatle("Starr", "drums"));
-            kSession.insert(new Beatle("McCartney", "bass"));
-            kSession.insert(new Beatle("Lennon", "guitar"));
-            kSession.insert(new Beatle("Harrison", "guitar"));
-
-            kSession.insert("Ringo"); // invoke the rule that calls the query implentation of backward chaining
-            kSession.fireAllRules(); // invoke all the rules
-        
-    }
-
-}

drools/backward-chaining/src/main/java/com/baeldung/model/Beatle.java

@@ -1,33 +0,0 @@
-package com.baeldung.model;
-
-import org.kie.api.definition.type.Position;
-
-public class Beatle {
-
-    @Position(0)
-    private String lastName;
-    @Position(1)
-    private String instrument;
-
-    public Beatle(String lastName, String instrument) {
-        this.lastName = lastName;
-        this.instrument = instrument;
-    }
-
-    public String getInstrument() {
-        return instrument;
-    }
-
-    public void setInstrument(String instrument) {
-        this.instrument = instrument;
-    }
-
-    public String getLastName() {
-        return lastName;
-    }
-
-    public void setLastName(String lastName) {
-        this.lastName = lastName;
-    }
-
-}

drools/backward-chaining/src/main/resources/META-INF/kmodule.xml

@@ -1,6 +0,0 @@
-<?xml version="1.0" encoding="UTF-8"?>
-<kmodule xmlns="http://jboss.org/kie/6.0.0/kmodule">
-    <kbase name="backward_chaining" packages="backward_chaining">
-        <ksession name="ksession-backward-chaining"/>
-    </kbase>
-</kmodule>

drools/backward-chaining/src/main/resources/META-INF/maven/pom.properties

@@ -1,3 +0,0 @@
-groupId=com.baeldung.drools
-artifactId=DroosBackwardChaining
-version=1.0.0-SNAPSHOT

drools/backward-chaining/src/main/resources/backward_chaining/Beatles.drl

@@ -1,44 +0,0 @@
-package com.baeldung
-
-import com.baeldung.model.Beatle;
-
-
-query whichBeatle(String lastName, String instrument) 
-  Beatle(lastName, instrument;)
-  or 
-  (Beatle(lastName, null;) 
-    and 
-   whichBeatle(null, instrument;)) //recursive call to the function that allows to search in a derivation tree structure
-end
-
-rule "Ringo"
-  when
-    String(this == "Ringo")
-    whichBeatle("Starr", "drums";)
-  then
-    System.out.println("The beatle is Ringo Starr");
-end
-
-rule "Paul"
-  when
-    String(this == "Paul")
-    whichBeatle("McCartney", "bass";)
-  then
-    System.out.println("The beatle is Paul McCartney");
-end
-
-rule "John"
-  when
-    String(this == "John")
-    whichBeatle("Lennon", "guitar";)
-  then
-    System.out.println("The beatle is John Lennon");
-end
-
-rule "George"
-  when
-    String(this == "George")
-    whichBeatle("Harrison", "guitar";)
-  then
-    System.out.println("The beatle is George Harrison");
-end

drools/backward-chaining/src/main/resources/backward_chaining/rules.drl

@@ -1,34 +0,0 @@
-package com.baeldung
-
-import com.baeldung.drools.model.Fact;
-
-global com.baeldung.drools.model.Result result;
-
-dialect  "mvel"
-
-query belongsTo(String x, String y)
-  Fact(x, y;)
-  or
-  (Fact(z, y;) and belongsTo(x, z;))
-end
-
-rule "Great Wall of China BELONGS TO Planet Earth"
-when
-    belongsTo("Great Wall of China", "Planet Earth";)
-then
-	result.setValue("Decision one taken: Great Wall of China BELONGS TO Planet Earth");
-end
-
-rule "Great Wall of China DOES NOT BELONG TO of Planet Earth"
-when
-    not belongsTo("Great Wall of China", "Planet Earth";)
-then
-    result.setValue("Decision two taken: Great Wall of China DOES NOT BELONG TO Planet Earth");
-end
-
-rule "print all facts"
-when
-    belongsTo(element, place;)
-then
-    result.addFact(element + " IS ELEMENT OF " + place);
-end

drools/backward-chaining/src/test/java/com/baeldung/test/BackwardChainingTest.java

@@ -1,54 +0,0 @@
-package com.baeldung.test;
-
-import org.junit.Before;
-import org.junit.Test;
-import org.kie.api.KieServices;
-import org.kie.api.runtime.KieContainer;
-import org.kie.api.runtime.KieSession;
-
-import com.baeldung.drools.model.Fact;
-import com.baeldung.drools.model.Result;
-
-import static junit.framework.TestCase.assertEquals;
-
-public class BackwardChainingTest {
-    private Result result;
-    private KieServices ks;
-    private KieContainer kContainer;
-    private KieSession ksession;
-
-    @Before
-    public void before() {
-        result = new Result();
-        ks = KieServices.Factory.get();
-        kContainer = ks.getKieClasspathContainer();
-        ksession = kContainer.newKieSession("ksession-backward-chaining");
-        ksession.setGlobal("result", result);
-    }
-
-    @Test
-    public void whenWallOfChinaIsGiven_ThenItBelongsToPlanetEarth() {
-
-        ksession.setGlobal("result", result);
-        ksession.insert(new Fact("Asia", "Planet Earth"));
-        ksession.insert(new Fact("China", "Asia"));
-        ksession.insert(new Fact("Great Wall of China", "China"));
-
-        ksession.fireAllRules();
-        
-        // Assert Decision one
-        assertEquals(result.getValue(), "Decision one taken: Great Wall of China BELONGS TO Planet Earth");
-    }
-
-    @Test
-    public void whenChinaIsNotGiven_ThenWallOfChinaDoesNotBelongToPlanetEarth() {
-        ksession.insert(new Fact("Asia", "Planet Earth"));
-        // ksession.insert(new Location("China", "Asia")); // not provided to force Decision two
-        ksession.insert(new Fact("Great Wall of China", "China"));
-        
-        ksession.fireAllRules();
-        
-        // Assert Decision two
-        assertEquals(result.getValue(), "Decision two taken: Great Wall of China DOES NOT BELONG TO Planet Earth");
-    }
-}

drools/pom.xml

@@ -1,14 +1,9 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<project xmlns="http://maven.apache.org/POM/4.0.0"
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
 	<modelVersion>4.0.0</modelVersion>
 
-    <groupId>com.baeldung</groupId>
 	<artifactId>drools</artifactId>
-    <version>1.0.0-SNAPSHOT</version>
-	
-	<packaging>pom</packaging>
 	
 	<parent>
 		<groupId>com.baeldung</groupId>

drools/src/main/java/com/baeldung/drools/backward_chaining/BackwardChaining.java

@@ -1,9 +1,8 @@
-package com.baeldung.drools;
+package com.baeldung.drools.backward_chaining;
 
-import org.kie.api.KieServices;
-import org.kie.api.runtime.KieContainer;
 import org.kie.api.runtime.KieSession;
 
+import com.baeldung.drools.config.DroolsBeanFactory;
 import com.baeldung.drools.model.Fact;
 import com.baeldung.drools.model.Result;
 
@@ -11,17 +10,17 @@ public class BackwardChaining {
     public static void main(String[] args) {
         Result result = new BackwardChaining().backwardChaining();
         System.out.println(result.getValue());
-        result.getFacts().stream().forEach(System.out::println);
+        result.getFacts()
+            .stream()
+            .forEach(System.out::println);
     }
 
     public Result backwardChaining() {
         Result result = new Result();
-        KieServices ks = KieServices.Factory.get();
+        KieSession ksession = new DroolsBeanFactory().getKieSession();
-        KieContainer kContainer = ks.getKieClasspathContainer();
-        KieSession ksession = kContainer.newKieSession("ksession-backward-chaining");
         ksession.setGlobal("result", result);
         ksession.insert(new Fact("Asia", "Planet Earth"));
-        // ksession.insert(new Fact("China", "Asia"));
+        ksession.insert(new Fact("China", "Asia"));
         ksession.insert(new Fact("Great Wall of China", "China"));
 
         ksession.fireAllRules();

drools/src/main/java/com/baeldung/drools/config/DroolsBeanFactory.java

@@ -3,7 +3,6 @@ package com.baeldung.drools.config;
 import org.drools.decisiontable.DecisionTableProviderImpl;
 import org.kie.api.KieServices;
 import org.kie.api.builder.*;
-import org.kie.api.io.KieResources;
 import org.kie.api.io.Resource;
 import org.kie.api.runtime.KieContainer;
 import org.kie.api.runtime.KieSession;
@@ -22,7 +21,7 @@ public class DroolsBeanFactory {
 
     private  KieFileSystem getKieFileSystem() throws IOException{
         KieFileSystem kieFileSystem = kieServices.newKieFileSystem();
-        List<String> rules=Arrays.asList("SuggestApplicant.drl","Product_rules.xls");
+        List<String> rules=Arrays.asList("BackwardChaining.drl","SuggestApplicant.drl","Product_rules.xls");
         for(String rule:rules){
             kieFileSystem.write(ResourceFactory.newClassPathResource(rule));
         }
@@ -56,9 +55,11 @@ public class DroolsBeanFactory {
         getKieRepository();
         KieFileSystem kieFileSystem = kieServices.newKieFileSystem();
 
+        kieFileSystem.write(ResourceFactory.newClassPathResource("com/baeldung/drools/rules/BackwardChaining.drl"));
         kieFileSystem.write(ResourceFactory.newClassPathResource("com/baeldung/drools/rules/SuggestApplicant.drl"));
         kieFileSystem.write(ResourceFactory.newClassPathResource("com/baeldung/drools/rules/Product_rules.xls"));
         
+        
         KieBuilder kb = kieServices.newKieBuilder(kieFileSystem);
         kb.buildAll();
         KieModule kieModule = kb.getKieModule();

drools/src/main/resources/com/baeldung/drools/rules/BackwardChaining.drl

@@ -1,4 +1,4 @@
-package com.baeldung
+package com.baeldung.drools.rules
 
 import com.baeldung.drools.model.Fact;
 

drools/src/test/java/com/baeldung/drools/backward_chaining/BackwardChainingTest.java

@@ -0,0 +1,36 @@
+package com.baeldung.drools.backward_chaining;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.kie.api.runtime.KieSession;
+
+import com.baeldung.drools.config.DroolsBeanFactory;
+import com.baeldung.drools.model.Fact;
+import com.baeldung.drools.model.Result;
+
+import static junit.framework.TestCase.assertEquals;
+
+public class BackwardChainingTest {
+    private Result result;
+    private KieSession ksession;
+ 
+    @Before
+    public void before() {
+        result = new Result();
+        ksession = new DroolsBeanFactory().getKieSession();
+    }
+
+    @Test
+    public void whenWallOfChinaIsGiven_ThenItBelongsToPlanetEarth() {
+
+        ksession.setGlobal("result", result);
+        ksession.insert(new Fact("Asia", "Planet Earth"));
+        ksession.insert(new Fact("China", "Asia"));
+        ksession.insert(new Fact("Great Wall of China", "China"));
+
+        ksession.fireAllRules();
+        
+        // Assert Decision one
+        assertEquals(result.getValue(), "Decision one taken: Great Wall of China BELONGS TO Planet Earth");
+    }
+}