JBPM6 Service task to execute java code

Question

I am new in JBPM6. My scenario is like this that i want to execute some java code using JBPM service task.From documentation i am not able to understand how to use domain sp

Answer 1

Here is how to add a handler inside a Eclipse maven project. I call it the Awesome handler, but your should pick a more specific name.

1) First create a work item definition file in src/main/resources/WorkItemDefinitions.wid. My icon file is located in src/main/resources.

import org.drools.core.process.core.datatype.impl.type.StringDataType;

[
  [
    "name" : "Awesome",
    "parameters" : [
      "Message1" : new StringDataType(),
       "Message2" : new StringDataType()
     ],
    "displayName" : "Awesome",
    "icon" : "icon-info.gif"
  ]
]

2) Create a Work Item Handler Config file in src/main/resources/META-INF/CustomWorkItemHandlers.conf

[
  "Awesome": new org.jbpm.examples.util.handler.AwesomeHandler()
]

3) Create a drools session config file: src/main/resources/META-INF/drools.session.conf

drools.workItemHandlers = CustomWorkItemHandlers.conf

4) Create your Handler so that it matches the class you defined in step 2

public class AwesomeHandler implements WorkItemHandler {

    public AwesomeHandler() {
        super();
    }

    public void executeWorkItem(WorkItem workItem, WorkItemManager manager) {
        System.out.println("Executing Awesome handler");
        manager.completeWorkItem(workItem.getId(), null);
    }

    public void abortWorkItem(WorkItem workItem, WorkItemManager manager) {
        System.out.println("Aborting");
    }
}

5) After you establish the handler, you must register it with your session.

//Get session
KieSession ksession = runtime.getKieSession();

//Register handlers
ksession.getWorkItemManager().registerWorkItemHandler("Awesome", new AwesomeHandler());

At this point you should restart eclipse. When eclipse opens, there should be a 'Custom Tasks' tab in the palette. It should contain an entry labeled 'Awesome' with the specified icon.

Answer 2

Apart from the (excellent) example provided by Mike, if your only goal is to execute some Java code, you can consider using a Script task instead (and just embed the Java code in your process) or reuse the already existing Service Task that can invoke an operation on a Java class.

Answer 3

I know the question is already answered, but I wanted to do the same (execute java code in service task) without creating work item definition (I did't want to use a custom task but a service task as it is). This is how I solved it:

here I read about the ServiceTaskHandler but I couldn't find very good info about the usage.

I read the ServiceTaskHandler code, it uses reflection to run your java code.

I found this (it says jbpm5-samples but I tested with jbpm 6.3), it uses a service task, the service task executes method "hello" from a Class (HelloService) you create:

package com.test;

import java.util.HashMap;
import java.util.Map;

public class HelloService {

    public DataOutput hello(com.test.DataInput name) {
        Map<String, Object> dataMap = new HashMap<String, Object>();
        dataMap.put("s", "Hello " + name.getDataMap().get("s") + "!");
        DataOutput output = new DataOutput(dataMap);
        return output;
    }

}

The ServiceTaskHandler is registered the same way as the step (5) in the answer marked correct:

//Get session
KieSession ksession = runtime.getKieSession();

//Register handlers
ksession.getWorkItemManager().registerWorkItemHandler("Service Task",        new ServiceTaskHandler());

After that I associated the service task with the java class (HelloService - method hello). To do that I used the eclipse bpmn modeler but I didn't find it very intuitive, so I opened the sample's bpmn file (BPMN2-ServiceProcess.bpmn2) with the modeler and filled my service task with the same stuff I read there.