[rules-users] Drools Flow Fluent API Help

[Dan Nathanson]

Hi,

I've been banging my head against this for days and just can't get it
to work.  At this point I'd like to just get the example code working.
 I've got a simple class that is currently being driven by a JUnit
test case.  I just want to create a Process flow and execute it.  I
don't care what it does at this point.  Hello world level stuff.

My method under test:

       public String runFlow() throws Exception {

       RuleFlowProcessFactory factory
= RuleFlowProcessFactory.createProcess("org.drools.process");
       factory
               // header
               .name("My process").packageName("org.drools")
               // nodes
               .startNode(1).name("Start").done()
               .actionNode(2).name("Action")
               .action("java", "System.out.println(\"Hello
World\");").done()
               .endNode(3).name("End").done()
               // connections
               .connection(1, 2)
               .connection(2, 3);

       RuleFlowProcess process = factory.validate().getProcess();

       KnowledgeBase knowledgeBase =
KnowledgeBaseFactory.newKnowledgeBase();
       KnowledgeBuilder builder =
KnowledgeBuilderFactory.newKnowledgeBuilder(knowledgeBase);

       Package pkg = new Package("package1");
       pkg.addProcess(process);
       RuleBase ruleBase = RuleBaseFactory.newRuleBase();
       ruleBase.addPackage(pkg);

       Collection<KnowledgePackage> kpackages =
builder.getKnowledgePackages();
       KnowledgePackage kpackage = new KnowledgePackageImp(pkg);
       kpackages.add(kpackage);
       knowledgeBase.addKnowledgePackages(kpackages);

       StatefulKnowledgeSession ksession =
knowledgeBase.newStatefulKnowledgeSession();

       KnowledgeRuntimeLogger logger =
KnowledgeRuntimeLoggerFactory.newConsoleLogger(ksession);

       ksession.startProcess("org.drools.process");

       return "foo";
   }

When I run this process, I get an exception when the Action node is
run.  It is a NPE and it happens because the metaData map in the
underlying ActionNode does not contain a KVP for "Action".  It looks
like that KVP is added in in the DroolsAction class when the public
void wire(Object object) method is called.  Unfortunately, I can't
figure out what causes that method to be called.  I'm pretty sure my
problem is with the set up of my knowledge base (the call to new
KnowledgePackageImp() is suspect), but I can't figure out how to set
up the knowledge base when building a RuleFlowProcess using the
RuleFlowProcessFactory.  None of the examples I can find show how to
do this.

Note that if I take out the Action node and just have Start and End
nodes, it works fine.

I am using Drools 5.1.0, but it doesn't work with Drools 5.0.1 either.

Any help would be appreciated.  The flat spot on my forehead is
getting flatter every day I continue to bang my head against the wall.

Here's the output (including KnowledgeRuntimeLogger output):

BEFORE RULEFLOW STARTED process:My process[id=org.drools.process]
BEFORE RULEFLOW NODE TRIGGERED node:Start[id=1] process:My
process[id=org.drools.process]
null process:My process[id=org.drools.process]
BEFORE RULEFLOW NODE TRIGGERED node:Action[id=2] process:My
process[id=org.drools.process]

java.lang.RuntimeException: unable to execute Action
       at
org.drools.workflow.instance.node.ActionNodeInstance.internalTrigger(ActionNodeInstance.java:56)
       at
org.drools.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:117)
       at
org.drools.workflow.instance.impl.NodeInstanceImpl.triggerConnection(NodeInstanceImpl.java:178)
       at
org.drools.workflow.instance.impl.NodeInstanceImpl.triggerCompleted(NodeInstanceImpl.java:144)
       at
org.drools.workflow.instance.node.StartNodeInstance.triggerCompleted(StartNodeInstance.java:49)
       at
org.drools.workflow.instance.node.StartNodeInstance.internalTrigger(StartNodeInstance.java:41)
       at
org.drools.workflow.instance.impl.NodeInstanceImpl.trigger(NodeInstanceImpl.java:117)
       at
org.drools.ruleflow.instance.RuleFlowProcessInstance.internalStart(RuleFlowProcessInstance.java:32)
       at
org.drools.process.instance.impl.ProcessInstanceImpl.start(ProcessInstanceImpl.java:192)
       at
org.drools.workflow.instance.impl.WorkflowProcessInstanceImpl.start(WorkflowProcessInstanceImpl.java:309)
       at
org.drools.common.AbstractWorkingMemory.startProcess(AbstractWorkingMemory.java:1644)
       at
org.drools.common.AbstractWorkingMemory.startProcess(AbstractWorkingMemory.java:1622)
       at
org.drools.impl.StatefulKnowledgeSessionImpl.startProcess(StatefulKnowledgeSessionImpl.java:301)
       at
com.proferi.epm.process.DroolsFlowManager.runFlow(DroolsFlowManager.java:75)
       at
com.proferi.epm.process.DroolsFlowManagerTest.testRunFlow(DroolsFlowManagerTest.java:33)
       at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
       at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
       at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
       at org.junit.internal.runners.TestMethod.invoke(TestMethod.java:59)
       at
org.junit.internal.runners.MethodRoadie.runTestMethod(MethodRoadie.java:98)
       at
org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:79)
       at
org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:87)
       at
org.junit.internal.runners.MethodRoadie.runTest(MethodRoadie.java:77)
       at org.junit.internal.runners.MethodRoadie.run(MethodRoadie.java:42)
       at
org.junit.internal.runners.JUnit4ClassRunner.invokeTestMethod(JUnit4ClassRunner.java:88)
       at
org.junit.internal.runners.JUnit4ClassRunner.runMethods(JUnit4ClassRunner.java:51)
       at
org.junit.internal.runners.JUnit4ClassRunner$1.run(JUnit4ClassRunner.java:44)
       at
org.junit.internal.runners.ClassRoadie.runUnprotected(ClassRoadie.java:27)
       at
org.junit.internal.runners.ClassRoadie.runProtected(ClassRoadie.java:37)
       at
org.junit.internal.runners.JUnit4ClassRunner.run(JUnit4ClassRunner.java:42)
       at org.junit.runner.JUnitCore.run(JUnitCore.java:130)
       at
com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:64)
Caused by: java.lang.NullPointerException
       at
org.drools.workflow.instance.node.ActionNodeInstance.internalTrigger(ActionNodeInstance.java:54)
       ... 34 more

Regards,

Dan Nathanson
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