jBPM - How to trace a lifecycle of a process

Just need to add a ProcesEventListener() to the ksession.

KnowledgeBase kbase = readKnowledgeBase();
StatefulKnowledgeSession ksession = kbase.newStatefulKnowledgeSession();

CustomProcessEventListener customProcessEventListener = new CustomProcessEventListener();
ksession.addEventListener(customProcessEventListener);
...
...

ksession.startProcess("com.sample.MyTaskFlow", params);

And here is the sample CustomProcessEventListener();

private static class CustomProcessEventListener implements ProcessEventListener {

 @Override
 public void afterNodeLeft(ProcessNodeLeftEvent arg0) {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void afterNodeTriggered(ProcessNodeTriggeredEvent arg0) {
  // TODO Auto-generated method stub
 }

 @Override
 public void afterProcessCompleted(ProcessCompletedEvent arg0) {
  // TODO Auto-generated method stub
  logger.debug("Process has completed.");
  System.exit(0);
 }

 @Override
 public void afterProcessStarted(ProcessStartedEvent arg0) {
  // TODO Auto-generated method stub
 }

 @Override
 public void afterVariableChanged(ProcessVariableChangedEvent arg0) {
  // TODO Auto-generated method stub
   
  }

 @Override
 public void beforeNodeLeft(ProcessNodeLeftEvent arg0) {
  // TODO Auto-generated method stub
   
 }

 @Override
 public void beforeNodeTriggered(ProcessNodeTriggeredEvent arg0) {
  // TODO Auto-generated method stub
   
 }

 @Override
 public void beforeProcessCompleted(ProcessCompletedEvent arg0) {
  // TODO Auto-generated method stub
  logger.debug("Process is going to be completed.");
 }

 @Override
 public void beforeProcessStarted(ProcessStartedEvent arg0) {
  // TODO Auto-generated method stub
  
 }

 @Override
 public void beforeVariableChanged(ProcessVariableChangedEvent arg0) {
  // TODO Auto-generated method stub
  
 }
 
}

As you can see, you can do many things on every stage of a process.

Drools again, example for beginner

Who would foresee that I will get my hand dirty again with drools? Well, after 13 months, here I am, looking at drools, again... now with jbpm too.
Anyway, it was good. Got better understanding about it and yeah, as usual, share.

I successfully made this:

I am not posting the codes here, you can request for it if you want.

The first process flow (can be in .rf or .bpmn) shows how to use Script Tasks. In the "Question" script, I ran these:

System.out.println("Who is the smartest man in the world?");

java.io.BufferedReader br = new java.io.BufferedReader(new 

                         java.io.InputStreamReader(System.in));

String name = null;

try {

name = br.readLine();

} catch (java.io.IOException e) {

System.out.println("Error!");

}

kcontext.setVariable("smart_guy", name);

The gateway after the "Question" script I check for this:

return smart_guy.equals("frank");

The "Error message" script just print error message. I ran the process.

ksession.startProcess("interactiveJava");

It will keep on asking you who the question until you say "frank". Pretty basic but it gives you better understand about how things run.

Here is the sample output.

The learning issues here will be:

• Define variable "smart_guy" in the flow/process.

• In the "Question" script, we set the user input to the process variable. 

     kcontext.setVariable("smart_guy", name);

• In the gateway constraint:

     return smart_guy.equals("frank");

For beginners, you should try it out your self.

Many thanks to Drools/jBPM development team and the community for their hard work. Many helpful resources are now available online compare to last year.