Exception while executing a class associated with user task

[vijayd]

I have associated a class to a user task and that task is assigned to kermit. Now when kermit commits the task, the class must be instantiate and execute ; But, I am getting an exception unable to instantiate a class "demo.tasklistener.DemoTaskListener" on activiti explorer and following error on the Tomcat :

12 Mar, 2014 11:52:04 AM org.apache.catalina.connector.CoyoteAdapter service
SEVERE: An exception or error occurred in the container during the request proce
ssing
java.lang.NoClassDefFoundError: com/vaadin/terminal/gwt/server/AbstractApplicati
onServlet
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClassCond(ClassLoader.java:632)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:616)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:14
1)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:283)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:58)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:197)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
        at org.apache.catalina.core.StandardWrapper.servletSecurityAnnotationSca
n(StandardWrapper.java:1139)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(Authentica
torBase.java:451)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.j
ava:164)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.j
ava:100)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:
562)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineVal
ve.java:118)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.jav
a:395)
        at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcesso
r.java:306)
        at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.pr
ocess(Http11AprProtocol.java:323)
        at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoin
t.java:1719)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExec
utor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor
.java:908)
        at java.lang.Thread.run(Thread.java:662)
Caused by: java.lang.ClassNotFoundException: com.vaadin.terminal.gwt.server.Abst
ractApplicationServlet
        at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
        … 24 more
11:52:17,663 ["http-apr-8080"-exec-7] ERROR org.activiti.engine.impl.interceptor
.CommandContext  - Error while closing command context
org.activiti.engine.ActivitiException: Exception while invoking TaskListener: de
mo.tasklistener.DemoTaskListener doesn't implement interface org.activiti.engine
.delegate.TaskListener
        at org.activiti.engine.impl.persistence.entity.TaskEntity.fireEvent(Task
Entity.java:553)
        at org.activiti.engine.impl.persistence.entity.TaskEntity.complete(TaskE
ntity.java:146)
        at org.activiti.engine.impl.cmd.CompleteTaskCmd.execute(CompleteTaskCmd.
java:39)
        at org.activiti.engine.impl.cmd.CompleteTaskCmd.execute(CompleteTaskCmd.
java:24)
        at org.activiti.engine.impl.cmd.NeedsActiveTaskCmd.execute(NeedsActiveTa
skCmd.java:61)
        at org.activiti.engine.impl.interceptor.CommandInvoker.execute(CommandIn
voker.java:24)
        at org.activiti.engine.impl.interceptor.CommandContextInterceptor.execut
e(CommandContextInterceptor.java:57)
        at org.activiti.spring.SpringTransactionInterceptor$1.doInTransaction(Sp
ringTransactionInterceptor.java:47)
        at org.springframework.transaction.support.TransactionTemplate.execute(T
ransactionTemplate.java:130)
        at org.activiti.spring.SpringTransactionInterceptor.execute(SpringTransa
ctionInterceptor.java:45)
        at org.activiti.engine.impl.interceptor.LogInterceptor.execute(LogInterc
eptor.java:31)
        at org.activiti.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecu
torImpl.java:40)
        at org.activiti.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecu
torImpl.java:35)
        at org.activiti.engine.impl.TaskServiceImpl.complete(TaskServiceImpl.jav
a:168)
        at org.activiti.explorer.ui.task.TaskDetailPanel$5.buttonClick(TaskDetai
lPanel.java:353)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:510)

        at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:164)
        at com.vaadin.ui.AbstractComponent.fireEvent(AbstractComponent.java:1219
)
        at com.vaadin.ui.Button.fireClick(Button.java:567)
        at com.vaadin.ui.Button.changeVariables(Button.java:223)
        at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.changeVar
iables(AbstractCommunicationManager.java:1460)
        at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVar
iableBurst(AbstractCommunicationManager.java:1404)
        at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVar
iables(AbstractCommunicationManager.java:1329)
        at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.doHandleU
idlRequest(AbstractCommunicationManager.java:761)
        at com.vaadin.terminal.gwt.server.CommunicationManager.handleUidlRequest
(CommunicationManager.java:325)
        at com.vaadin.terminal.gwt.server.AbstractApplicationServlet.service(Abs
tractApplicationServlet.java:501)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:304)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:210)
        at org.activiti.explorer.filter.ExplorerFilter.doFilter(ExplorerFilter.j
ava:44)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:243)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:210)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV
alve.java:240)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextV
alve.java:164)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(Authentica
torBase.java:462)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.j
ava:164)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.j
ava:100)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:
562)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineVal
ve.java:118)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.jav
a:395)
        at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcesso
r.java:306)
        at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.pr
ocess(Http11AprProtocol.java:323)
        at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoin
t.java:1719)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExec
utor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor
.java:908)
        at java.lang.Thread.run(Thread.java:662)
Caused by: org.activiti.engine.ActivitiIllegalArgumentException: demo.tasklisten
er.DemoTaskListener doesn't implement interface org.activiti.engine.delegate.Tas
kListener
        at org.activiti.engine.impl.bpmn.helper.ClassDelegate.getTaskListenerIns
tance(ClassDelegate.java:106)
        at org.activiti.engine.impl.bpmn.helper.ClassDelegate.notify(ClassDelega
te.java:90)
        at org.activiti.engine.impl.delegate.TaskListenerInvocation.invoke(TaskL
istenerInvocation.java:34)
        at org.activiti.engine.impl.delegate.DelegateInvocation.proceed(Delegate
Invocation.java:37)
        at org.activiti.engine.impl.delegate.DefaultDelegateInterceptor.handleIn
vocation(DefaultDelegateInterceptor.java:25)
        at org.activiti.engine.impl.persistence.entity.TaskEntity.fireEvent(Task
Entity.java:549)
        … 49 more
12 Mar, 2014 11:52:17 AM com.vaadin.Application terminalError
SEVERE: Terminal error:
com.vaadin.event.ListenerMethod$MethodException: Invocation of method buttonClic
k in org.activiti.explorer.ui.task.TaskDetailPanel$5 failed.
        at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:530)

        at com.vaadin.event.EventRouter.fireEvent(EventRouter.java:164)
        at com.vaadin.ui.AbstractComponent.fireEvent(AbstractComponent.java:1219
)
        at com.vaadin.ui.Button.fireClick(Button.java:567)
        at com.vaadin.ui.Button.changeVariables(Button.java:223)
        at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.changeVar
iables(AbstractCommunicationManager.java:1460)
        at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVar
iableBurst(AbstractCommunicationManager.java:1404)
        at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.handleVar
iables(AbstractCommunicationManager.java:1329)
        at com.vaadin.terminal.gwt.server.AbstractCommunicationManager.doHandleU
idlRequest(AbstractCommunicationManager.java:761)
        at com.vaadin.terminal.gwt.server.CommunicationManager.handleUidlRequest
(CommunicationManager.java:325)
        at com.vaadin.terminal.gwt.server.AbstractApplicationServlet.service(Abs
tractApplicationServlet.java:501)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:304)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:210)
        at org.activiti.explorer.filter.ExplorerFilter.doFilter(ExplorerFilter.j
ava:44)
        at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(Appl
icationFilterChain.java:243)
        at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationF
ilterChain.java:210)
        at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperV
alve.java:240)
        at org.apache.catalina.core.StandardContextValve.invoke(StandardContextV
alve.java:164)
        at org.apache.catalina.authenticator.AuthenticatorBase.invoke(Authentica
torBase.java:462)
        at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.j
ava:164)
        at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.j
ava:100)
        at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:
562)
        at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineVal
ve.java:118)
        at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.jav
a:395)
        at org.apache.coyote.http11.Http11AprProcessor.process(Http11AprProcesso
r.java:306)
        at org.apache.coyote.http11.Http11AprProtocol$Http11ConnectionHandler.pr
ocess(Http11AprProtocol.java:323)
        at org.apache.tomcat.util.net.AprEndpoint$SocketProcessor.run(AprEndpoin
t.java:1719)
        at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExec
utor.java:886)
        at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor
.java:908)
        at java.lang.Thread.run(Thread.java:662)
Caused by: org.activiti.engine.ActivitiException: Exception while invoking TaskL
istener: demo.tasklistener.DemoTaskListener doesn't implement interface org.acti
viti.engine.delegate.TaskListener
        at org.activiti.engine.impl.persistence.entity.TaskEntity.fireEvent(Task
Entity.java:553)
        at org.activiti.engine.impl.persistence.entity.TaskEntity.complete(TaskE
ntity.java:146)
        at org.activiti.engine.impl.cmd.CompleteTaskCmd.execute(CompleteTaskCmd.
java:39)
        at org.activiti.engine.impl.cmd.CompleteTaskCmd.execute(CompleteTaskCmd.
java:24)
        at org.activiti.engine.impl.cmd.NeedsActiveTaskCmd.execute(NeedsActiveTa
skCmd.java:61)
        at org.activiti.engine.impl.interceptor.CommandInvoker.execute(CommandIn
voker.java:24)
        at org.activiti.engine.impl.interceptor.CommandContextInterceptor.execut
e(CommandContextInterceptor.java:57)
        at org.activiti.spring.SpringTransactionInterceptor$1.doInTransaction(Sp
ringTransactionInterceptor.java:47)
        at org.springframework.transaction.support.TransactionTemplate.execute(T
ransactionTemplate.java:130)
        at org.activiti.spring.SpringTransactionInterceptor.execute(SpringTransa
ctionInterceptor.java:45)
        at org.activiti.engine.impl.interceptor.LogInterceptor.execute(LogInterc
eptor.java:31)
        at org.activiti.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecu
torImpl.java:40)
        at org.activiti.engine.impl.cfg.CommandExecutorImpl.execute(CommandExecu
torImpl.java:35)
        at org.activiti.engine.impl.TaskServiceImpl.complete(TaskServiceImpl.jav
a:168)
        at org.activiti.explorer.ui.task.TaskDetailPanel$5.buttonClick(TaskDetai
lPanel.java:353)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.
java:39)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAcces
sorImpl.java:25)
        at java.lang.reflect.Method.invoke(Method.java:597)
        at com.vaadin.event.ListenerMethod.receiveEvent(ListenerMethod.java:510)

        … 30 more
Caused by: org.activiti.engine.ActivitiIllegalArgumentException: demo.tasklisten
er.DemoTaskListener doesn't implement interface org.activiti.engine.delegate.Tas
kListener
        at org.activiti.engine.impl.bpmn.helper.ClassDelegate.getTaskListenerIns
tance(ClassDelegate.java:106)
        at org.activiti.engine.impl.bpmn.helper.ClassDelegate.notify(ClassDelega
te.java:90)
        at org.activiti.engine.impl.delegate.TaskListenerInvocation.invoke(TaskL
istenerInvocation.java:34)
        at org.activiti.engine.impl.delegate.DelegateInvocation.proceed(Delegate
Invocation.java:37)
        at org.activiti.engine.impl.delegate.DefaultDelegateInterceptor.handleIn
vocation(DefaultDelegateInterceptor.java:25)
        at org.activiti.engine.impl.persistence.entity.TaskEntity.fireEvent(Task
Entity.java:549)
        … 49 more


**>> I have put all jars that were told to put in tomcat lib also I added Vaadin jar in tomcat lib

[martin_grofcik]

Hi,


Caused by: org.activiti.engine.ActivitiException: Exception while invoking TaskListener: demo.tasklistener.DemoTaskListener doesn't implement interface org.activiti.engine.delegate.TaskListener

DemoTaskListener should implement TaskListener interface.

Regards
Martin

[vijayd]

Hi,
This is my class, you can see DemoTaskListener has implemented TaskListener interface :

package demo.tasklistener;

import org.activiti.engine.delegate.DelegateTask;
import org.activiti.engine.delegate.TaskListener;

public class DemoTaskListener implements TaskListener {

  private static final long serialVersionUID = 1L;

@Override
public void notify(DelegateTask arg0) {

  System.out.println("\n\n\n\t\t\tTaskListener Executed….\n\n\n");
}

}

[martin_grofcik]

Hi Vijay.
In that case you could follow existing working example and try to compare what  is different in yours… to find an error.
One example could be
org.activiti.engine.test.bpmn.usertask.UserTaskTest#testCompleteAfterParallelGateway

an activiti sources.
Regards
Martin