My first encounter with jBPM

Long story, short story. When I was working in one of my projects in Mexico, somebody mentioned something about BPM or BPEL and how practical de idea/concept was, because now we can mix the knowledge of the Business People with the Developers, by using some kind of cool diagrams to do Process Modeling.

And now I had to create a project which essentially it's a WorkFlow but we need some features like keeping the state of each execution (so we can trace it easily and resume the process if by any chance is stopped) "et all" and then, when I saw that One of the requirements was to integrate this miniworkflow with an existing App deployed on jBoss 4 with Seam 2.1 (I'd talk later about this framework, for all those like me who love Spring Framework), then I have to use jBPM 3 instead of 4 or 5 OUCH :'(
"But then, I realize that JBPM4 can work flawlessly on JBoss 4"
What do we need???
No much, Eclipse Helios (3.6)
Install these features:

• JBoss Tools - http://download.jboss.org/jbosstools/updates/development/helios (don't forget to install jBPM support!)
• Graphiti - http://download.eclipse.org/graphiti/updates/0.7.1
• BPMN2 - http://codehoop.com/bpmn2

The concept is really simple, we just need to model the flow (I'll use the Designer to do this)

But it needs some logic inside its guts, so I'll add something called Handlers and some personalized tags (which is a really cool feture)
This is our model translated into XML <?xml version="1.0" encoding="UTF-8"?> <process-definition xmlns="urn:jbpm.org:jpdl-3.2" name="myRTCAP"> <start-state name="start"> <transition to="Verify Enrollment"/> </start-state> <state name="Verify Enrollment"> <transition to="Enrollment Exists?"> <action class="com.kaplan.rtcap.action.VerifyEnrollmentActionHandler"/> </transition> </state> <state name="Retrieve Enrollment Details"> <transition to="Save Enrollment Details"> <action class="com.kaplan.rtcap.action.SaveEnrollmentDetailsActionHandler"/> </transition> </state> <state name="Save Enrollment Details"> <transition to="Retrieve Student Details"/> </state> <state name="Retrieve Student Details"> <transition to="Student Exists?"> <action class="com.kaplan.rtcap.action.RetrieveStudentDetailsActionHandler"/> </transition> </state> <state name="Save Student Details"> <event type="node-enter"> <action class="com.kaplan.rtcap.action.SaveStudentActionHandler"/> </event> <transition to="Bulk Post"/> </state> <state name="Update Student Details"> <event type="node-enter"> <action class="com.kaplan.rtcap.action.UpdateStudentActionHandler"/> </event> <transition to="Bulk Post"/> </state> <state name="Bulk Post"> <event type="node-enter"> <action class="com.kaplan.rtcap.action.BulkPostActionHandler"/> </event> <transition to="end" /> </state> <decision name="Enrollment Exists?"> <handler class="com.kaplan.rtcap.action.decision.EnrollmentExistDecisionActionHandler"/> <transition name="ExistingEnrollment" to="end"> <action class="com.kaplan.rtcap.action.EnrollmentExistActionHandler" /> </transition> <transition name="NewEnrollment" to="Retrieve Enrollment Details" > <action class="com.kaplan.rtcap.action.RetrieveEnrollmentDetailsActionHandler"/> </transition> </decision> <decision name="Student Exists?"> <handler class="com.kaplan.rtcap.action.decision.StudentExistDecisionActionHandler"/> <transition name="NewStudent" to="Save Student Details"/> <transition name="ExistingStudent" to="Update Student Details"/> </decision> <end-state name="end"> <event type="node-enter"> <script>System.out.println("End of the process")</script> </event> </end-state> </process-definition>
On my implementation, the process will run by itself, it's going to be a "FIRE AND FORGET";

On my case the process will wait for a certain amount of time and the it will start, it'll make one decision and it will execute something and then the End :)
<state name="Wait"> <transition to="Verify Enrollment" name="toVerifyEnrollment"> <action class="com.kaplan.jbpm.action.rtcap.WaitActionHandler"> <minutes>0</minutes> <seconds>0</seconds> </action> </transition> </state>
The logic will be implemented by Implementing some Interfaces:
org.jbpm.graph.def.ActionHandler org.jbpm.graph.node.DecisionHandler
public class WaitActionHandler extends BaseCustomHandler implements ActionHandler { private static Logger log = Logger.getLogger(WaitActionHandler.class); private static final long serialVersionUID = 1L; private Integer seconds = 0; private Integer minutes = 0; public void execute(ExecutionContext executionContext) throws Exception { String enrollmentId = (String)this.getVariableFromContext(GenericConstants.ENROLLMENT_ID, executionContext); //Calculate waiting time Long time = 0L; if(minutes>0){ time = minutes*(60*1000L) + (seconds*1000L); }else{ time = seconds*1000L; } if(time>=1000){//If pause was at least 1 second show this logging message log.debug("Waiting for "+GenericConstants.ENROLLMENT_ID+"="+enrollmentId+", during "+minutes+"min "+seconds+"sec"); //Suspend (Pause) Process execution this.suspendExecution(executionContext); //Wait Thread.sleep(time); log.debug("Resuming process for "+GenericConstants.ENROLLMENT_ID+"="+enrollmentId); //Resume this.resumeExecution(executionContext); } }
public class VerifyEnrollmentActionHandler extends BaseCustomHandler implements ActionHandler { private static Logger log = Logger.getLogger(VerifyEnrollmentActionHandler.class); private static final long serialVersionUID = 1L; public void execute(ExecutionContext executionContext) throws Exception { //TODO: This class only demonstrates that the flow is being followed : Nothing important happens here! String enrollmentId = (String)this.getVariableFromContext(GenericConstants.ENROLLMENT_ID, executionContext); log.debug("Execute for "+GenericConstants.ENROLLMENT_ID+"="+enrollmentId); } }
public class StudentExistDecisionActionHandler extends BaseCustomHandler implements DecisionHandler { private static final long serialVersionUID = -902776688182390371L; private static Logger log = Logger .getLogger(StudentExistDecisionActionHandler.class); @In(value="studentIdLookupDAO") //Use Component.getInstance("purchaseDao") instead private StudentIdLookupDAO studentIdLookupDAO; public String decide(ExecutionContext executionContext) throws Exception { StudentDetailsVO studentDetails = (StudentDetailsVO)this.getVariableFromContext(GenericConstants.STUDENT_DETAILS_KEY, executionContext); String decision = null; List<StudentIdLookup> listStudentIdLookup = new ArrayList<StudentIdLookup>(); log.debug("Using Annotations: "+studentIdLookupDAO); this.studentIdLookupDAO = (StudentIdLookupDAO) Component.getInstance("studentIdLookupDAO"); log.debug("Using Seam.componentForName: "+studentIdLookupDAO); //TODO: Check if this Student already exists on STUDENT_ID_LOOKUP to determine if is NEW or EXISTING (SAVE or UPDATE) try{ listStudentIdLookup = studentIdLookupDAO.getByStudentId(studentDetails.getStudentId()); }catch (Exception ex) { log.error("Error while calling studentIdLookupDAO",ex); } if (!listStudentIdLookup.isEmpty()) { decision = GenericConstants.EXISTING_STUDENT; } else { decision = GenericConstants.NEW_STUDENT; } log.debug("Deciding what to do in for "+studentDetails+"\tDecision taken = " + decision); return decision; } } And Voila!!!

Soon I'll talk a little bit about jBoss SEAM! (How I implemented a REST Service FACILITO!)