Delegate to Seam the management of my JBPM4 engine

The problem was really simple, it's just implement a Singleton without writing it :P

I have a simple class, but I just need it to be loaded when the app starts, because my class will load the JBPM4 engine (and that should be done only once - this process may take up to 4 seconds, which will make really slow the first request coming to my End-Point)
But let me write more code and less words
Just add to your class these tags @Name("rtcapProcessExecutor") @Scope(ScopeType.APPLICATION) @Startup @BypassInterceptors @Install(precedence = Install.APPLICATION) public final class RtcapProcessRunner { .... }
Define which method will be your Creation method (Initialization method), on my case the one which will load the Engine @Create public void startup() { try{ log.info("Creating JBPM process engine using configuration file ("+GenericConstants.JBPM_CONFIG_FILE+") and Loading process definition ("+GenericConstants.PROCESS_DEFINITION_FILE+")"); this.processEngine = new Configuration().setResource(GenericConstants.JBPM_CONFIG_FILE).buildProcessEngine(); this.repositoryService = this.processEngine.getRepositoryService(); this.executionService = this.processEngine.getExecutionService(); this.repositoryService.createDeployment().addResourceFromClasspath(GenericConstants.PROCESS_DEFINITION_FILE).setName(GenericConstants.RTCAP).setTimestamp(new Date().getTime()).deploy(); }catch (Exception ex) { log.fatal("Error while loading RTCAP process definition and configuration file",ex); } }
Now the one which will Destroy your class (shutdown my JBPM4 engine) and release resources @Destroy public void shutdown() { log.info("Destroying JBPM process engine"); if (this.processEngine != null) { this.processEngine.close(); } }
and optionally, your Constructor @Constructor public RtcapProcessRunner(){ log.debug("Creating instance of RtcapProcessRunner"); }

Simple, Isnt' it?
Now you can inject this Seam Component using Injection into another Seam Component, just like this
@In(value="rtcapProcessExecutor", create=true, required=true) private RtcapProcessRunner rtcapProcessRunner; ... //And invoke any public method of that instance, just like this this.rtcapProcessRunner.executeProcessInstance(variablesMap, messageEntity); //And always will be the same instance (a Singleton!)

Fix javax.ejb.NoSuchEJBException: Could not find stateful bean on Seam and JBPM4

When I was using Google to look for answers to my problem, I found a lot of posts asking for a solution, just like me, but not a concrete answer (IMHO, JBoss has really poor documentation, compared with Spring, even their forums have less information), like this case

But I got a solution!!! (u_u)
Let me tell you my story...

On one of my Handlers I was using a ServiceImpl, just like this: public class UpdateStudentActionHandler extends BaseCustomJbpm4Handler implements ActivityBehaviour { private static final long serialVersionUID = 2971366515413177358L; private static Logger log = Logger.getLogger(UpdateStudentActionHandler.class); private IStudentDetailsService studentDetailsService; public void execute(ActivityExecution activityExecution) throws Exception { .... this.studentDetailsService = (IStudentDetailsService) this.getSeamComponentInstance("studentDetailsServiceBean"); try{ result = this.studentDetailsService.updateStudentDetails(studentDetails, enrollmentDetails); }catch (Exception ex) { .... } .... } }
This is my ServiceImpl @Name("studentDetailsServiceBean") @AutoCreate public class StudentDetailsServiceImpl implements IStudentDetailsService { private static Logger log = Logger.getLogger(StudentDetailsServiceImpl.class); @In(value="userDAO", create=true) private UserDAO userDAO; @In(value="studentIdLookupDAO", create=true) private StudentIdLookupDAO studentIdLookupDAO; @In(value="countryCodeDAO", create=true) private CountryCodeDAO countryCodeDAO; @In(value="deltakProductDAO", create=true) private DeltakProductDAO deltakProductDAO; @In(value="courseAccessHomeService", create=true) private CourseAccessHome courseAccessHomeService; @In(value="userCourseAccessDAO", create=true) private UserCourseAccessDAO userCourseAccessDAO; @In(value="productMixDAO", create=true) private ProductMixDAO productMixDAO; @In(value="componentAccessDAO", create=true) private ComponentAccessDAO componentAccessDAO; @In(value="courseAccessStatusDAO", create=true) private CourseAccessStatusDAO courseAccessStatusDAO; @In(value="courseAccessHsgDAO", create=true) private CourseAccessHsgDAO courseAccessHsgDAO; /* * Service method which will handle the Transaction */ @Transactional(TransactionPropagationType.REQUIRED) public Boolean updateStudentDetails(StudentDetails studentDetails, EnrollmentDetails enrollmentDetails) throws Exception { Boolean result = false; try{ User user = this.userDAO.lookupUserById(studentDetails.getUserId()); //Update user related data user = this.updateDpsTables(user, studentDetails, enrollmentDetails); //This one is common for Save and Update! CourseAccess courseAccess = this.saveCourseAccessData(user, enrollmentDetails); //For this phase we only SAVE enrollments/couseAccess - no need to update result = true; //Populate courseAccessId by reference enrollmentDetails.setCourseAccessId(courseAccess.getId()); }catch (Exception ex) { log.error("Error while Updating StudentDetails [studentId="+studentDetails.getStudentId()+", enrollmentId="+enrollmentDetails.getEnrollmentId()+"] into DB",ex); throw ex; } return result; } }
And my getSeamComponentInstance method protected Object getSeamComponentInstance(final String componentName){ //For Asyc Calls we have to do this to avoid "IllegalStateException: No event context active" when using Component.getInstance() if (!Contexts.isApplicationContextActive() && !Contexts.isEventContextActive() && !Contexts.isSessionContextActive()){ Lifecycle.beginCall(); } return Component.getInstance(componentName); }

As you can see, this doesn't have anything really weird, I just injecting a Bean into another class, and invoke one its methods! Simple (pure DI)

When you test it, it works! After it's been deployed, it works again, but...

After some period of inactivity... Boooom! The same line of code (the one where I invoke one of the methods of my ServiceImpl) was throwing an this

javax.ejb.NoSuchEJBException: Could not find stateful bean: 4sg5nl-4371oh-gsvwkdiv-1-gsvwst2j-1b
 at org.jboss.ejb3.cache.simple.SimpleStatefulCache.get(SimpleStatefulCache.java:492)
 at org.jboss.ejb3.cache.simple.SimpleStatefulCache.get(SimpleStatefulCache.java:443)
 at org.jboss.ejb3.stateful.StatefulInstanceInterceptor.invoke(StatefulInstanceInterceptor.java:61)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.aspects.security.AuthenticationInterceptor.invoke(AuthenticationInterceptor.java:77)
 at org.jboss.ejb3.security.Ejb3AuthenticationInterceptor.invoke(Ejb3AuthenticationInterceptor.java:106)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.ejb3.ENCPropagationInterceptor.invoke(ENCPropagationInterceptor.java:46)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.ejb3.asynchronous.AsynchronousInterceptor.invoke(AsynchronousInterceptor.java:106)
 at org.jboss.aop.joinpoint.MethodInvocation.invokeNext(MethodInvocation.java:101)
 at org.jboss.ejb3.stateful.StatefulContainer.localInvoke(StatefulContainer.java:204)
 at org.jboss.ejb3.stateful.StatefulLocalProxy.invoke(StatefulLocalProxy.java:117)
 at $Proxy81.afterTransactionRollback(Unknown Source)
 at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
 at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
 at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
 at java.lang.reflect.Method.invoke(Method.java:597)
 at org.jboss.seam.util.Reflections.invoke(Reflections.java:22)
 at org.jboss.seam.intercept.RootInvocationContext.proceed(RootInvocationContext.java:32)
 at org.jboss.seam.intercept.ClientSideInterceptor$1.proceed(ClientSideInterceptor.java:76)
 at org.jboss.seam.intercept.RootInterceptor.invoke(RootInterceptor.java:107)
 at org.jboss.seam.intercept.ClientSideInterceptor.invoke(ClientSideInterceptor.java:54)
 at org.javassist.tmp.java.lang.Object_$$_javassist_seam_5.afterTransactionRollback(Object_$$_javassist_seam_5.java)
 at org.jboss.seam.transaction.UTTransaction.rollback(UTTransaction.java:70)
 at org.jboss.seam.util.Work.workInTransaction(Work.java:68)
 at org.jboss.seam.transaction.TransactionInterceptor.aroundInvoke(TransactionInterceptor.java:91)
 at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
 at org.jboss.seam.core.MethodContextInterceptor.aroundInvoke(MethodContextInterceptor.java:44)
 at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:68)
 at org.jboss.seam.intercept.RootInterceptor.invoke(RootInterceptor.java:107)
 at org.jboss.seam.intercept.JavaBeanInterceptor.interceptInvocation(JavaBeanInterceptor.java:185)
 at org.jboss.seam.intercept.JavaBeanInterceptor.invoke(JavaBeanInterceptor.java:103)
 at com.kaplan.service.impl.StudentDetailsServiceImpl_$$_javassist_seam_11.updateStudentDetails(StudentDetailsServiceImpl_$$_javassist_seam_11.java)
 at com.kaplan.jbpm.action.integration.jbpm4.UpdateStudentActionHandler.execute(UpdateStudentActionHandler.java:44)
 at org.jbpm.pvm.internal.wire.usercode.UserCodeActivityBehaviour.execute(UserCodeActivityBehaviour.java:42)
 at org.jbpm.pvm.internal.model.op.ExecuteActivity.perform(ExecuteActivity.java:60)
 at org.jbpm.pvm.internal.model.ExecutionImpl.performAtomicOperationSync(ExecutionImpl.java:672)
 at org.jbpm.pvm.internal.model.op.ExecuteActivityMessage.executeVoid(ExecuteActivityMessage.java:45)
 at org.jbpm.pvm.internal.job.MessageImpl.execute(MessageImpl.java:46)
 at org.jbpm.pvm.internal.job.MessageImpl.execute(MessageImpl.java:32)
 at org.jbpm.pvm.internal.cmd.ExecuteJobCmd.execute(ExecuteJobCmd.java:79)
 at org.jbpm.pvm.internal.cmd.ExecuteJobCmd.execute(ExecuteJobCmd.java:41)
 at org.jbpm.pvm.internal.svc.DefaultCommandService.execute(DefaultCommandService.java:42)
 at org.jbpm.pvm.internal.tx.StandardTransactionInterceptor.execute(StandardTransactionInterceptor.java:50)
 at org.jbpm.pvm.internal.svc.EnvironmentInterceptor.executeInNewEnvironment(EnvironmentInterceptor.java:53)
 at org.jbpm.pvm.internal.svc.EnvironmentInterceptor.execute(EnvironmentInterceptor.java:40)
 at org.jbpm.pvm.internal.svc.RetryInterceptor.execute(RetryInterceptor.java:56)
 at org.jbpm.pvm.internal.svc.SkipInterceptor.execute(SkipInterceptor.java:43)
 at org.jbpm.pvm.internal.jobexecutor.JobParcel.run(JobParcel.java:48)
 at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:441)
 at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:303)
 at java.util.concurrent.FutureTask.run(FutureTask.java:138)
 at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
 at java.lang.Thread.run(Thread.java:619)

WTF!!!

What!!! I'm not even using stateful beans!!!, I'm using plain POJO's not even stateless!
This is how it works Seam, when you inject a Component using Components.getInstance, you just get a Proxy, and that proxy references the REAL instance of the class you want to invoke, but for any weird reason, that instance it has been removed! Then, why the freaking Proxy points to a nonexistent object? No idea (u_u).

Let's force Seam to create a new instance if it doesn't exist and specify that I don't want a Stateful bean by passing the scope Stateless (you can try with another one, but Stateless seems to be working just fine) and this is it
protected Object getSeamComponentInstance(final String componentName, final ScopeType scopeType){ //For Asyc Calls we have to do this to avoid "IllegalStateException: No event context active" when using Component.getInstance() if (!Contexts.isApplicationContextActive() || !Contexts.isEventContextActive() || !Contexts.isSessionContextActive() || !Contexts.isConversationContextActive() || !Contexts.isMethodContextActive()){ Lifecycle.beginCall(); } return Component.getInstance(componentName, scopeType, true); } public class UpdateStudentActionHandler extends BaseCustomJbpm4Handler implements ActivityBehaviour { private static final long serialVersionUID = 2971366515413177358L; private static Logger log = Logger.getLogger(UpdateStudentActionHandler.class); private IStudentDetailsService studentDetailsService; public void execute(ActivityExecution activityExecution) throws Exception { .... this.studentDetailsService = (IStudentDetailsService) this.getSeamComponentInstance("studentDetailsServiceBean", ScopeType.STATELESS); try{ result = this.studentDetailsService.updateStudentDetails(studentDetails, enrollmentDetails); }catch (Exception ex) { .... } .... } }

And after 1 night of inactivity, the error was gone (one for the team!)