java.lang.RuntimeException: Unexpected global [result] - drools

Question

I have this class, that reads rule files, insert facts and run rules.
public class RuleRunner {
private KieServices kieServices = KieServices.Factory.get();
public enum RuleType {
XLS,
DRL;
}
private void prepareSession(String ruleResource, RuleType type) {
KieFileSystem kieFileSystem = kieServices.newKieFileSystem();
Resource resource = kieServices.getResources().newClassPathResource(ruleResource);
switch(type) {
case XLS: {
resource.setResourceType(ResourceType.DTABLE);
break;
}
case DRL: {
resource.setResourceType(ResourceType.DRL);
break;
}
}
kieFileSystem.write(resource);
KieBuilder kieBuilder = kieServices.newKieBuilder(kieFileSystem);
kieBuilder.buildAll();
if (hasErrors(kieBuilder)) {
System.out.println("Failed to build!");
return;
}
}
private boolean hasErrors(KieBuilder builder) {
if (builder.getResults().getMessages().size() > 0) {
return true;
}
return false;
}
public void runRules(Object[] facts, GlobalVariable[] variables, String ruleResource, RuleType type) {
prepareSession(ruleResource, type);
KieContainer kieContainer = kieServices.newKieContainer(kieServices.getRepository().getDefaultReleaseId());
KieSession kieSession = kieContainer.newKieSession();
for (GlobalVariable variable: variables) {
kieSession.setGlobal(variable.getVariableName(), variable);
}
for(Object fact: facts) {
kieSession.insert(fact);
}
kieSession.fireAllRules();
kieSession.dispose();
}
}
And I have this rule
package com.pack.drools.apps;
import com.pack.drools.apps.domain.Person;
import com.pack.drools.apps.domain.GlobalVariable;
global GlobalVariable result
rule "if person has less that 10 cash then hes poor"
when
$person:Person(cash < 10)
then
result.setResult(-1);
end
rule "if person has more than 90 cash then hes rich"
when
$person:Person(cash > 90)
then
result.setResult(-2);
end
rule "if person has more than 10 and less than 90 then hes average"
when
$person:Person(cash >= 10 && cash <= 90)
then
result.setResult(-3);
end
However when I try to run my application
package pack.rup.drools.apps;
import pack.rup.drools.apps.core.RuleRunner;
import pack.rup.drools.apps.core.RuleRunner.RuleType;
import pack.rup.drools.apps.domain.GlobalVariable;
import pack.rup.drools.apps.domain.Person;
public class Main {
private static final String DEFAULT_PACKAGE = "pack/rup/drools/apps/";
private static final String XLS_FILE = DEFAULT_PACKAGE + "rule.xls";
private static final String DRL_FILE = DEFAULT_PACKAGE + "rule.drl";
public static void main(String[] args) {
RuleRunner ruleRunner = new RuleRunner();
// build fact
Person person = new Person();
person.setName("John");
person.setCash(100);
GlobalVariable result = new GlobalVariable();
result.setVariableName("result");
// ruleRunner.runRules(new Object[] { person }, new GlobalVariable[] { result }, XLS_FILE, RuleType.XLS);
ruleRunner.runRules(new Object[] { person }, new GlobalVariable[] { result }, DRL_FILE, RuleType.DRL);
System.out.println("Rule result: " + result.getResult());
}
}
my log looks like this
10:13:00.974 [main] INFO o.d.c.k.b.impl.KieRepositoryImpl - KieModule was added: MemoryKieModule[releaseId=org.default:arti
fact:1.0.0-SNAPSHOT]
10:13:00.982 [main] INFO o.d.c.k.b.impl.ClasspathKieProject - Found kmodule: file:/D:/workTestProjects/simpleDroolsApps/sda
-core/build/resources/main/META-INF/kmodule.xml
10:13:00.982 [main] DEBUG o.d.c.k.b.impl.ClasspathKieProject - KieModule URL type=file url=/D:/workTestProjects/simpleDrools
Apps/sda-core/build/resources/main
10:13:01.026 [main] WARN o.d.c.k.b.impl.ClasspathKieProject - Unable to find pom.properties in /D:/workTestProjects/simpleD
roolsApps/sda-core/build/resources/main
10:13:01.027 [main] WARN o.d.c.k.b.impl.ClasspathKieProject - As folder project tried to fall back to pom.xml, but could no
t find one for null
10:13:01.027 [main] WARN o.d.c.k.b.impl.ClasspathKieProject - Unable to load pom.properties from/D:/workTestProjects/simple
DroolsApps/sda-core/build/resources/main
10:13:01.027 [main] WARN o.d.c.k.b.impl.ClasspathKieProject - Cannot find maven pom properties for this project. Using the
container's default ReleaseId
10:13:01.027 [main] DEBUG o.d.c.k.b.impl.ClasspathKieProject - Discovered classpath module org.default:artifact:1.0.0-SNAPSH
OT
10:13:01.028 [main] INFO o.d.c.k.b.impl.KieRepositoryImpl - KieModule was added: FileKieModule[releaseId=org.default:artifa
ct:1.0.0-SNAPSHOT,file=D:\workTestProjects\simpleDroolsApps\sda-core\build\resources\main]
10:13:01.035 [main] WARN o.d.c.k.b.impl.AbstractKieModule - No files found for KieBase defaultKieBase, searching folder D:\
workTestProjects\simpleDroolsApps\sda-core\build\resources\main
10:13:01.131 [main] DEBUG o.drools.core.impl.KnowledgeBaseImpl - Starting Engine in PHREAK mode
Exception in thread "main" java.lang.RuntimeException: Unexpected global [result]
at org.drools.core.impl.StatefulKnowledgeSessionImpl.setGlobal(StatefulKnowledgeSessionImpl.java:1163)
at pack.rup.drools.apps.core.RuleRunner.runRules(RuleRunner.java:57)
at pack.rup.drools.apps.Main.main(Main.java:27)
:sda-core:run FAILED

Answer 1

It seems that you must use a particular directory when writing DRL or XLS resources to the KieFileSystem. Try
String filename = ...; // code that set filename to (e.g.) rule.drl
kieFileSystem.write( "src/main/resources/" + filename, resource );
Also, in your DRL you have
import com.pack.drools.apps.domain....
whereas in Main.java there is
import pack.rup.drools.apps.domain....
These imports should be from the same package.
Edit To test what globals are in the session:
Globals globals = kieSession.getGlobals();
System.out.println( globals.getGlobalKeys() );

Answer 2

We spent 2 days with my colleague and finally figured out that "Unexpected global" error happens when your DRL is empty because of compilation errors, that's why addGlobal() can't find any global declaration.
Once DRL compiler does not throw any exception on errors, instead you can check it yourself using:
if (kieBuilder.hasErrors()) {
System.out.print( kieBuilder.getErrors() );
}

Answer 3

If you insert a global, you must consume it. For example, if you have:
ArrayList<Thing> myThings = new ArrayList<Thing>();
kSession.setGlobal("myThings", myThings);
In your DRL files, you must have at least one matching:
global ArrayList<Thing> myThings;
Otherwise, you get:
java.lang.RuntimeException: Unexpected global [myThings]
at org.drools.core.impl.StatefulKnowledgeSessionImpl.setGlobal(StatefulKnowledgeSessionImpl.java:1200)
at com.sample.ThingTest.test(ThingTest.java:37)