Activiti: Unable to obtain process instance variables if one of them is serializable object

Created on 15 Sep 2018 · 14Comments · Source: Activiti/Activiti

I created process instance with this code:

    @Timed
    @GetMapping("/start")
    public ResponseEntity<ProcessInstance> start() throws URISyntaxException {
        Offer offer = new Offer();
        StartProcessPayload payload = ProcessPayloadBuilder
                .start()
                .withProcessDefinitionKey(PROCESS_NAME)
                .withProcessInstanceName("New offer")
                .withVariable("offer", offer)
                .withVariable("owner", SecurityUtils.getCurrentUserLogin().get())
                .build();
        ProcessInstance instance = processRuntime.start(payload);
        return ResponseEntity.created(new URI("/api/process/start/" + instance.getId()))
                .headers(HeaderUtil.createEntityCreationAlert(PROCESS_NAME, instance.getId()))
                .body(instance);
    }

Offer is simple POJO with name and description. I try to get process instance variables in this way:

        GetVariablesPayload payload = new GetVariablesPayload(processInstanceId);
        List<VariableInstance> variables = processRuntime.variables(payload);

Unfortunately, I get an error:

java.lang.NullPointerException: null
        at org.activiti.engine.impl.persistence.entity.ByteArrayRef.ensureInitialized(ByteArrayRef.java:87)
        at org.activiti.engine.impl.persistence.entity.ByteArrayRef.getBytes(ByteArrayRef.java:40)
        at org.activiti.engine.impl.persistence.entity.VariableInstanceEntityImpl.getBytes(VariableInstanceEntityImpl.java:101)
        at org.activiti.engine.impl.variable.ByteArrayType.getValue(ByteArrayType.java:31)
        at org.activiti.engine.impl.variable.SerializableType.getValue(SerializableType.java:59)
        at org.activiti.engine.impl.persistence.entity.VariableInstanceEntityImpl.getValue(VariableInstanceEntityImpl.java:124)
        at org.activiti.runtime.api.model.impl.APIVariableInstanceConverter.from(APIVariableInstanceConverter.java:29)
        at org.activiti.runtime.api.model.impl.APIVariableInstanceConverter.from(APIVariableInstanceConverter.java:21)
        at org.activiti.runtime.api.model.impl.ListConverter.from(ListConverter.java:27)
        at org.activiti.runtime.api.impl.ProcessRuntimeImpl.variables(ProcessRuntimeImpl.java:276)
        at org.activiti.runtime.api.impl.ProcessRuntimeImpl$$FastClassBySpringCGLIB$$60a3d48.invoke(<generated>)
        at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
        at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:746)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
        at org.springframework.security.access.intercept.aopalliance.MethodSecurityInterceptor.invoke(MethodSecurityInterceptor.java:69)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
        at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
        at org.activiti.runtime.api.impl.ProcessRuntimeImpl$$EnhancerBySpringCGLIB$$54dff862.variables(<generated>)
        at com.bpm.micro.web.rest.ProcessResource.updateTask(ProcessResource.java:83)
        at com.bpm.micro.web.rest.ProcessResource$$FastClassBySpringCGLIB$$b2eed923.invoke(<generated>)
        at org.springframework.cglib.proxy.MethodProxy.invoke(MethodProxy.java:204)
        at org.springframework.aop.framework.CglibAopProxy$CglibMethodInvocation.invokeJoinpoint(CglibAopProxy.java:746)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:163)
        at org.springframework.aop.aspectj.MethodInvocationProceedingJoinPoint.proceed(MethodInvocationProceedingJoinPoint.java:88)
        at com.bpm.micro.aop.logging.LoggingAspect.logAround(LoggingAspect.java:85)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:564)
        at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethodWithGivenArgs(AbstractAspectJAdvice.java:644)
        at org.springframework.aop.aspectj.AbstractAspectJAdvice.invokeAdviceMethod(AbstractAspectJAdvice.java:633)
        at org.springframework.aop.aspectj.AspectJAroundAdvice.invoke(AspectJAroundAdvice.java:70)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
        at org.springframework.aop.aspectj.AspectJAfterThrowingAdvice.invoke(AspectJAfterThrowingAdvice.java:62)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
        at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:92)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
        at com.ryantenney.metrics.spring.TimedMethodInterceptor.invoke(TimedMethodInterceptor.java:48)
        at com.ryantenney.metrics.spring.TimedMethodInterceptor.invoke(TimedMethodInterceptor.java:34)
        at com.ryantenney.metrics.spring.AbstractMetricMethodInterceptor.invoke(AbstractMetricMethodInterceptor.java:59)
        at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:185)
        at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
        at com.bpm.micro.web.rest.ProcessResource$$EnhancerBySpringCGLIB$$42d7c727.updateTask(<generated>)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.base/java.lang.reflect.Method.invoke(Method.java:564)
        at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:209)
        at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:136)
        at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:877)
        at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:783)
        at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
        at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:991)
        at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:925)
        at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:974)
        at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:866)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:687)
        at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:851)
        at javax.servlet.http.HttpServlet.service(HttpServlet.java:790)
        at io.undertow.servlet.handlers.ServletHandler.handleRequest(ServletHandler.java:74)
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:129)
        at com.codahale.metrics.servlet.AbstractInstrumentedFilter.doFilter(AbstractInstrumentedFilter.java:111)
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
        at org.springframework.web.filter.CorsFilter.doFilterInternal(CorsFilter.java:96)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
        at org.springframework.boot.actuate.web.trace.servlet.HttpTraceFilter.doFilterInternal(HttpTraceFilter.java:90)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:320)
        at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:127)
        at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:91)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
        at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:119)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
        at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:137)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
        at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:111)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
        at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:170)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
        at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:63)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
        at org.springframework.security.oauth2.provider.authentication.OAuth2AuthenticationProcessingFilter.doFilter(OAuth2AuthenticationProcessingFilter.java:176)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
        at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:116)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
        at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:66)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
        at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:105)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
        at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:56)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:334)
        at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:215)
        at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:178)
        at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:357)
        at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:270)
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
        at org.springframework.web.filter.RequestContextFilter.doFilterInternal(RequestContextFilter.java:99)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
        at org.springframework.web.filter.HttpPutFormContentFilter.doFilterInternal(HttpPutFormContentFilter.java:109)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
        at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:93)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
        at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.filterAndRecordMetrics(WebMvcMetricsFilter.java:155)
        at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.filterAndRecordMetrics(WebMvcMetricsFilter.java:123)
        at org.springframework.boot.actuate.metrics.web.servlet.WebMvcMetricsFilter.doFilterInternal(WebMvcMetricsFilter.java:108)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
        at org.springframework.web.filter.CharacterEncodingFilter.doFilterInternal(CharacterEncodingFilter.java:200)
        at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107)
        at io.undertow.servlet.core.ManagedFilter.doFilter(ManagedFilter.java:61)
        at io.undertow.servlet.handlers.FilterHandler$FilterChainImpl.doFilter(FilterHandler.java:131)
        at io.undertow.servlet.handlers.FilterHandler.handleRequest(FilterHandler.java:84)
        at io.undertow.servlet.handlers.security.ServletSecurityRoleHandler.handleRequest(ServletSecurityRoleHandler.java:62)
        at io.undertow.servlet.handlers.ServletChain$1.handleRequest(ServletChain.java:64)
        at io.undertow.servlet.handlers.ServletDispatchingHandler.handleRequest(ServletDispatchingHandler.java:36)
        at io.undertow.servlet.handlers.security.SSLInformationAssociationHandler.handleRequest(SSLInformationAssociationHandler.java:132)
        at io.undertow.servlet.handlers.security.ServletAuthenticationCallHandler.handleRequest(ServletAuthenticationCallHandler.java:57)
        at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
        at io.undertow.security.handlers.AbstractConfidentialityHandler.handleRequest(AbstractConfidentialityHandler.java:46)
        at io.undertow.servlet.handlers.security.ServletConfidentialityConstraintHandler.handleRequest(ServletConfidentialityConstraintHandler.java:64)
        at io.undertow.security.handlers.AuthenticationMechanismsHandler.handleRequest(AuthenticationMechanismsHandler.java:60)
        at io.undertow.servlet.handlers.security.CachedAuthenticatedSessionHandler.handleRequest(CachedAuthenticatedSessionHandler.java:77)
        at io.undertow.security.handlers.AbstractSecurityContextAssociationHandler.handleRequest(AbstractSecurityContextAssociationHandler.java:43)
        at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
        at io.undertow.server.handlers.PredicateHandler.handleRequest(PredicateHandler.java:43)
        at io.undertow.servlet.handlers.SessionRestoringHandler.handleRequest(SessionRestoringHandler.java:119)
        at io.undertow.servlet.handlers.ServletInitialHandler.handleFirstRequest(ServletInitialHandler.java:292)
        at io.undertow.servlet.handlers.ServletInitialHandler.access$100(ServletInitialHandler.java:81)
        at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:138)
        at io.undertow.servlet.handlers.ServletInitialHandler$2.call(ServletInitialHandler.java:135)
        at io.undertow.servlet.core.ServletRequestContextThreadSetupAction$1.call(ServletRequestContextThreadSetupAction.java:48)
        at io.undertow.servlet.core.ContextClassLoaderSetupAction$1.call(ContextClassLoaderSetupAction.java:43)
        at io.undertow.servlet.handlers.ServletInitialHandler.dispatchRequest(ServletInitialHandler.java:272)
        at io.undertow.servlet.handlers.ServletInitialHandler.access$000(ServletInitialHandler.java:81)
        at io.undertow.servlet.handlers.ServletInitialHandler$1.handleRequest(ServletInitialHandler.java:104)
        at io.undertow.server.Connectors.executeRootHandler(Connectors.java:336)
        at io.undertow.server.HttpServerExchange$1.run(HttpServerExchange.java:830)
        at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1135)
        at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:635)
        at java.base/java.lang.Thread.run(Thread.java:844)

enhancement

Source

mkawczynski07

Most helpful comment

It seems to me that we can close this issue and address any remaining concerns under https://github.com/Activiti/Activiti/issues/2074 So will close and can revisit (please comment) if anyone thinks we need to keep this open.

ryandawsonuk on 12 Nov 2018

🎉1 😄1 👍1

All 14 comments

@mkawczynski07 thank you for reporting this.. are you using Beta1?
The problem seems to make sense to me. You are sending an object that cannot be deserialised inside the RuntimeBundle. The Offer class will need to be in the RuntimeBundle class path in order to get that working. Does that make sense?

salaboy on 17 Sep 2018

Make sense ... how to check that @Salaboy ?

mkawczynski07 on 17 Sep 2018

@mkawczynski07 how to check what? you will need to add the jar that contains the Offer class into the Runtime Bundle. We want to provide more dynamic types support in the future, but we are not quite there yet.

salaboy on 17 Sep 2018

@Salaboy but what you exactly mean by Runtime Bundle? I found this.

Offer class is in the same java project/package as my endpoint. So both of them are in the same classloader. Also, the same problem is when I try to add a list of strings(List) as a project variable.

I debug my method and null pointer is in this class at this method:

  private void ensureInitialized() {
    if (id != null && entity == null) {
      entity = Context.getCommandContext().getByteArrayEntityManager().findById(id);
      name = entity.getName();
    }
  }

entity = Context.getCommandContext().getByteArrayEntityManager().findById(id);

When I checked this class on github Context

public static CommandContext getCommandContext() {
    Stack<CommandContext> stack = getStack(commandContextThreadLocal);
    if (stack.isEmpty()) {
      return null;
    }
    return stack.peek();
  }

Probably stack is empty and this method return null. I will try to set up activiti project on my laptop and mayby write a test case for this(if it is posible :).

mkawczynski07 on 18 Sep 2018

@mkawczynski07 that will be really useful. We might be missing something in the configuration of the new APIs for serialization so a reproducer will be extremely useful to fix this asap.

And you got the right link for what a runtime bundle is... if you are planning to deploy your services on kubernetes we tend to recommend using (and modifying/extending) our cloud components approach instead of writing your own services. But it is up to you. We can discuss this further if you are interested.

salaboy on 18 Sep 2018

@salaboy @mkawczynski07
Hi. I fixed this issue and made the pull request https://github.com/Activiti/Activiti/pull/2046.
Please review this one.

daisuke-yoshimoto on 3 Oct 2018

Variables(serializable)

In engine layer, we can handle variables by using Java APIs like RuntimeService.setVariable/getVariable.If the parameter value over the argument of RuntimeService.setVariable matches the following conditions, the variable is stored in the database as binary(Table ACT_GE_BYTEARRAY Column BYTES_).

Condition
- byte[]
- https://github.com/Activiti/Activiti/blob/develop/activiti-engine/src/main/java/org/activiti/engine/impl/variable/ByteArrayType.java
- A character string of 4000 or more characters
- https://github.com/Activiti/Activiti/blob/develop/activiti-engine/src/main/java/org/activiti/engine/impl/variable/LongStringType.java
- com.fasterxml.jackson.databind.JsonNode
- https://github.com/Activiti/Activiti/blob/develop/activiti-engine/src/main/java/org/activiti/engine/impl/variable/LongJsonType.java
- java.io.Serializable
- https://github.com/Activiti/Activiti/blob/develop/activiti-engine/src/main/java/org/activiti/engine/impl/variable/SerializableType.java

Cause of this issue

When the API that acquires the variable is called, the following processing is performed in the internal processing of the Engine, and then the variable is returned to the caller.
- If variable's type is serializable, engine get value by fetching Table ACT_GE_BYTEARRAY.
- Engine deserialize value to each data type(byte[], String, JsonNode, Serializable).
In the APIs(RuntimeService.getVariableInstances/getVariableInstancesLocal) of this issue , the above processing is not executed inside the Engine. So, when the caller access value, the caller try to fetch binary value from ACT_GE_BYTEARRAY. But, since outside of Engine, NullPointerException occurs.

daisuke-yoshimoto on 16 Oct 2018

@mkawczynski07 @salaboy
Hi. Is it OK to close the issue?

Since the problem was fixed, I think that this exception will not be reproduced.
https://github.com/Activiti/Activiti/pull/2046

daisuke-yoshimoto on 20 Oct 2018

@salaboy
I created an issue on the serialization method of variables that you were concerned with before gitter.
https://github.com/Activiti/Activiti/issues/2074

daisuke-yoshimoto on 20 Oct 2018

@daisuke-yoshimoto
@salaboy

The way to get a Serializable variable value is to do:

SomeSerializable myVar = (SomeSerializable) runtimeService.getVariable(processInstance.getId(), "myVar");

Doing getValue on a list of variable instances is not recommended, because for a list of 10 Serializable variables this would mean 10 database calls to the ACT_GE_BYTEARRAY table.