Cannot load class

Shruti · May 14, 2021, 9:03am

Hi,

Want to know how exactly the classes are loaded by camunda.

I have 3 separate Spring boot microservices:

WebUI: Camunda web ui
notations: Storing all the BPMN files(from this only the BPMNs are deployed)
Listener: Having all the listeners(Java delegate, execution listeners, task listeners)

When I run WebUI, notations and listener MSs locally all the listener classes are loaded and executed by the WebUI MS.

But when I deploy all the three on server and afterwards change(add/remove) the listener MS, the new classes are not found by the WebUI MS.

How to handle deployments? Do I need any MS restarts? Are there any configurations with the help of which the changes can be managed?

I have set the camunda.bpm.job-execution.deployment-aware=true, but this is not helping. Even I have added the asynchronous continuations as in:

What care should be taken off while deploying such setup?

Is it compulsory that I should create a war file of my project or still I can go it with jar?(How to deploy a Camunda Spring Boot application to an external application server - Just In Time Software Development)

PFB the log:

2021-05-14 14:44:43.522 WARN 1 — [nio-5070-exec-9] org.camunda.bpm.engine.rest.exception : ENGINE-REST-HTTP500 org.camunda.bpm.engine.rest.exception.RestException: Cannot submit task form cceb8b02-b494-11eb-9ac0-acde48001122: ENGINE-09008 Exception while instantiating class ‘com.listener.TestListener’: ENGINE-09017 Cannot load class ‘com.listener.TestListener’: com.listener.TestListener
at org.camunda.bpm.engine.rest.sub.task.impl.TaskResourceImpl.submit(TaskResourceImpl.java:165)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.base/java.lang.reflect.Method.invoke(Unknown Source)
at org.glassfish.jersey.server.model.internal.ResourceMethodInvocationHandlerFactory.lambda$static$0(ResourceMethodInvocationHandlerFactory.java:52)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher$1.run(AbstractJavaResourceMethodDispatcher.java:124)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.invoke(AbstractJavaResourceMethodDispatcher.java:167)
at org.glassfish.jersey.server.model.internal.JavaResourceMethodDispatcherProvider$ResponseOutInvoker.doDispatch(JavaResourceMethodDispatcherProvider.java:176)
at org.glassfish.jersey.server.model.internal.AbstractJavaResourceMethodDispatcher.dispatch(AbstractJavaResourceMethodDispatcher.java:79)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.invoke(ResourceMethodInvoker.java:469)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:391)
at org.glassfish.jersey.server.model.ResourceMethodInvoker.apply(ResourceMethodInvoker.java:80)
at org.glassfish.jersey.server.ServerRuntime$1.run(ServerRuntime.java:253)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:248)
at org.glassfish.jersey.internal.Errors$1.call(Errors.java:244)
at org.glassfish.jersey.internal.Errors.process(Errors.java:292)
at org.glassfish.jersey.internal.Errors.process(Errors.java:274)
at org.glassfish.jersey.internal.Errors.process(Errors.java:244)
at org.glassfish.jersey.process.internal.RequestScope.runInScope(RequestScope.java:265)
at org.glassfish.jersey.server.ServerRuntime.process(ServerRuntime.java:232)
at org.glassfish.jersey.server.ApplicationHandler.handle(ApplicationHandler.java:680)
at org.glassfish.jersey.servlet.WebComponent.serviceImpl(WebComponent.java:392)
at org.glassfish.jersey.servlet.WebComponent.service(WebComponent.java:346)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:365)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:318)
at org.glassfish.jersey.servlet.ServletContainer.service(ServletContainer.java:205)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:231)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:53)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.camunda.bpm.engine.rest.filter.CacheControlFilter.doFilter(CacheControlFilter.java:45)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.camunda.bpm.engine.rest.filter.EmptyBodyFilter.doFilter(EmptyBodyFilter.java:99)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.camunda.bpm.webapp.impl.engine.ProcessEnginesFilter.applyFilter(ProcessEnginesFilter.java:144)
at org.camunda.bpm.webapp.impl.filter.AbstractTemplateFilter.doFilter(AbstractTemplateFilter.java:58)
at org.camunda.bpm.spring.boot.starter.webapp.filter.LazyDelegateFilter.doFilter(LazyDelegateFilter.java:60)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.camunda.bpm.webapp.impl.security.filter.headersec.HttpHeaderSecurityFilter.doFilter(HttpHeaderSecurityFilter.java:87)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.camunda.bpm.spring.boot.starter.webapp.filter.SpringBootCsrfPreventionFilter.doFilter(SpringBootCsrfPreventionFilter.java:136)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.camunda.bpm.webapp.impl.security.filter.SecurityFilter.doFilterSecure(SecurityFilter.java:73)
at org.camunda.bpm.webapp.impl.security.filter.SecurityFilter.doFilter(SecurityFilter.java:57)
at org.camunda.bpm.spring.boot.starter.webapp.filter.LazyDelegateFilter.doFilter(LazyDelegateFilter.java:60)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.camunda.bpm.webapp.impl.security.auth.AuthenticationFilter$1.execute(AuthenticationFilter.java:62)
at org.camunda.bpm.webapp.impl.security.auth.AuthenticationFilter$1.execute(AuthenticationFilter.java:60)
at org.camunda.bpm.webapp.impl.security.SecurityActions.runWithAuthentications(SecurityActions.java:44)
at org.camunda.bpm.webapp.impl.security.auth.AuthenticationFilter.doFilter(AuthenticationFilter.java:60)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:100)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.FormContentFilter.doFilterInternal(FormContentFilter.java:93)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:109)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:201)
at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:119)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:193)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:166)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:202)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:96)
at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:541)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:139)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:92)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74)
at org.apache.catalina.valves.RemoteIpValve.invoke(RemoteIpValve.java:747)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:343)
at org.apache.coyote.http11.Http11Processor.service(Http11Processor.java:367)
at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:65)
at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:868)
at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1639)
at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:49)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61)
at java.base/java.lang.Thread.run(Unknown Source)
Caused by: org.camunda.bpm.engine.ProcessEngineException: ENGINE-09008 Exception while instantiating class ‘com.listener.TestListener’: ENGINE-09017 Cannot load class ‘com.listener.TestListener’: com.listener.TestListener
at org.camunda.bpm.engine.impl.util.EngineUtilLogger.exceptionWhileInstantiatingClass(EngineUtilLogger.java:89)
at org.camunda.bpm.engine.impl.util.ClassDelegateUtil.instantiateDelegate(ClassDelegateUtil.java:54)
at org.camunda.bpm.engine.impl.bpmn.listener.ClassDelegateExecutionListener.getExecutionListenerInstance(ClassDelegateExecutionListener.java:60)
at org.camunda.bpm.engine.impl.bpmn.listener.ClassDelegateExecutionListener.notify(ClassDelegateExecutionListener.java:52)
at org.camunda.bpm.engine.impl.bpmn.listener.ClassDelegateExecutionListener.notify(ClassDelegateExecutionListener.java:38)
at org.camunda.bpm.engine.impl.core.instance.CoreExecution.invokeListener(CoreExecution.java:101)
at org.camunda.bpm.engine.impl.core.operation.AbstractEventAtomicOperation.execute(AbstractEventAtomicOperation.java:55)
at org.camunda.bpm.engine.impl.interceptor.AtomicOperationInvocation.execute(AtomicOperationInvocation.java:99)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.invokeNext(CommandInvocationContext.java:131)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performNext(CommandInvocationContext.java:111)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performOperation(CommandInvocationContext.java:86)
at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:645)
at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:619)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl.leaveActivityViaTransitions(PvmExecutionImpl.java:1017)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl.leaveActivityViaTransition(PvmExecutionImpl.java:960)
at org.camunda.bpm.engine.impl.bpmn.behavior.BpmnActivityBehavior.performOutgoingBehavior(BpmnActivityBehavior.java:101)
at org.camunda.bpm.engine.impl.bpmn.behavior.BpmnActivityBehavior.performDefaultOutgoingBehavior(BpmnActivityBehavior.java:55)
at org.camunda.bpm.engine.impl.bpmn.behavior.FlowNodeActivityBehavior.doLeave(FlowNodeActivityBehavior.java:56)
at org.camunda.bpm.engine.impl.bpmn.behavior.AbstractBpmnActivityBehavior.doLeave(AbstractBpmnActivityBehavior.java:62)
at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationActivityLeave.execute(PvmAtomicOperationActivityLeave.java:56)
at org.camunda.bpm.engine.impl.pvm.runtime.operation.PvmAtomicOperationActivityLeave.execute(PvmAtomicOperationActivityLeave.java:32)
at org.camunda.bpm.engine.impl.interceptor.AtomicOperationInvocation.execute(AtomicOperationInvocation.java:99)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.invokeNext(CommandInvocationContext.java:131)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performNext(CommandInvocationContext.java:111)
at org.camunda.bpm.engine.impl.interceptor.CommandInvocationContext.performOperation(CommandInvocationContext.java:86)
at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:645)
at org.camunda.bpm.engine.impl.persistence.entity.ExecutionEntity.performOperation(ExecutionEntity.java:619)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl$6.callback(PvmExecutionImpl.java:1937)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl$6.callback(PvmExecutionImpl.java:1934)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl.continueExecutionIfNotCanceled(PvmExecutionImpl.java:2004)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl.dispatchDelayedEventsAndPerformOperation(PvmExecutionImpl.java:1953)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl.dispatchDelayedEventsAndPerformOperation(PvmExecutionImpl.java:1934)
at org.camunda.bpm.engine.impl.bpmn.behavior.FlowNodeActivityBehavior.leave(FlowNodeActivityBehavior.java:52)
at org.camunda.bpm.engine.impl.bpmn.behavior.UserTaskActivityBehavior.signal(UserTaskActivityBehavior.java:66)
at org.camunda.bpm.engine.impl.pvm.runtime.PvmExecutionImpl.signal(PvmExecutionImpl.java:728)
at org.camunda.bpm.engine.impl.persistence.entity.TaskEntity.complete(TaskEntity.java:336)
at org.camunda.bpm.engine.impl.cmd.SubmitTaskFormCmd.execute(SubmitTaskFormCmd.java:94)
at org.camunda.bpm.engine.impl.cmd.SubmitTaskFormCmd.execute(SubmitTaskFormCmd.java:43)
at org.camunda.bpm.engine.impl.interceptor.CommandExecutorImpl.execute(CommandExecutorImpl.java:28)
at org.camunda.bpm.engine.impl.interceptor.CommandContextInterceptor.execute(CommandContextInterceptor.java:110)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor$1.doInTransaction(SpringTransactionInterceptor.java:46)
at org.springframework.transaction.support.TransactionTemplate.execute(TransactionTemplate.java:140)
at org.camunda.bpm.engine.spring.SpringTransactionInterceptor.execute(SpringTransactionInterceptor.java:44)
at org.camunda.bpm.engine.impl.interceptor.ProcessApplicationContextInterceptor.execute(ProcessApplicationContextInterceptor.java:70)
at org.camunda.bpm.engine.impl.interceptor.LogInterceptor.execute(LogInterceptor.java:33)
at org.camunda.bpm.engine.impl.FormServiceImpl.submitTaskForm(FormServiceImpl.java:91)
at org.camunda.bpm.engine.rest.sub.task.impl.TaskResourceImpl.submit(TaskResourceImpl.java:148)
… 92 more
Caused by: org.camunda.bpm.engine.ClassLoadingException: ENGINE-09017 Cannot load class ‘com.listener.TestListener’: com.listener.TestListener
at org.camunda.bpm.engine.impl.util.EngineUtilLogger.classLoadingException(EngineUtilLogger.java:146)
at org.camunda.bpm.engine.impl.util.ReflectUtil.loadClass(ReflectUtil.java:111)
at org.camunda.bpm.engine.impl.util.ClassDelegateUtil.instantiateDelegate(ClassDelegateUtil.java:46)
… 137 more
Caused by: java.lang.ClassNotFoundException: com.listener.TestListener
at org.springframework.boot.web.embedded.tomcat.TomcatEmbeddedWebappClassLoader.loadClass(TomcatEmbeddedWebappClassLoader.java:72)
at org.apache.catalina.loader.WebappClassLoaderBase.loadClass(WebappClassLoaderBase.java:1188)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Unknown Source)
at org.camunda.bpm.engine.impl.util.ReflectUtil.loadClass(ReflectUtil.java:88)
… 138 more

Niall · May 17, 2021, 10:28am

Hi @Shruti
Can you format your post a little better? if you paste stack trace it’s easier to read it if it’s formatted correctly. You can find more detail on formatting in the FAQ

Also could you explain exactly what you do in order cause the error and exactly what you’ve done with regards to the async before/after in a n attempt to resolve the issue?

Shruti · May 17, 2021, 12:07pm

Hi @Niall,

I have 3 spring boot Micro services as below:

WebUI: Camunda web ui
notations: Storing all the BPMN files(from this only the BPMNs are deployed)
Listener: Having all the listeners(Java delegate, execution listeners, task listeners)

I have created a simple BPMN in notations MS, having 2 user tasks, Task A and Task B. Task B has the listener configured in it.

When I ran the above 3 MSs locally for the first time the listener configured into BPMN was found by the WebUI service. Even after deploying all the 3 MSs on the server (K8s cluster) the initial setup was working.

Then afterwards I add a new listener(TestListener implementing JavaDelegate) to Listener MS, and configured it in Task B as task/execution listener. While testing the changes locally the exception was thrown. I tried deploying the changes, but there also i got the issue.

So to resolve the issue, I have set the asyncBefore=true for Task B, and have configured the camunda.bpm.job-execution.deployment-aware: true in resources/application.yml of all the MSs. This didn’t solve the issue.

Ingo_Richtsmeier · May 17, 2021, 3:54pm

Hi @Shruti,

All async continuations will happen on this server.

One option could be to disable the job executor on the ui- and the deployment-server. And remove the deployment aware setting for the running job executor.

Another option is to give up the separation of deployment server from the one containing all the java code.

You can merge these services into a single one to get it running.

Hope this helps, Ingo

system · January 30, 2024, 1:06pm