Mutliple instance / correlation problem

Camunda 7 Topics Discussion & Questions
1

Hello,

In my project, i use camunda with the following setup :

  • spring-boot : 2.3.0.RELEASE
  • camunda : 7.12.0
  • camunda-bpm-assert : 5.0.0

In my bpmn multiple_instance.bpmn (see above), a parallel multiple instance subprocess is used.
A collection is declared with an element variable (for mapping) - no loop cardinality is used.
I’m not able to correlate a message with an instance of this subprocess. The error thrown by camunda looks like :

ENGINE-13031 Cannot correlate a message with name ‘X’ to a single execution. Y executions match the correlation keys

Here are two reproducers. The collection (items) used by the multiple instance subprocess is given at a process instance creation. Then, we try to correlate with an item of the collection.

    @Test
    public void reproducer1() {

        List<String> items = Arrays.asList("item1", "item2", "items3");

        BpmnAwareTests
                .runtimeService()
                .createProcessInstanceByKey("multiplie_instance_problem")
                .businessKey("businessKey")
                .setVariable("items", items)
                .execute();


        Map<String, Object> correlationKeysMap = new HashMap<>();
        correlationKeysMap.put("item", "item1");

        BpmnAwareTests
                .runtimeService()
                .correlateMessage(
                        "message_for_subprocess",
                        "businessKey",
                        correlationKeysMap,
                        null);
    }

    @Test
    public void reproducer2() {
        List<String> items = Arrays.asList("item1", "item2", "items3");

        BpmnAwareTests
                .runtimeService()
                .createProcessInstanceByKey("multiplie_instance_problem")
                .businessKey("businessKey")
                .setVariable("items", items)
                .execute();

        BpmnAwareTests
                .runtimeService()
                .createMessageCorrelation("message_for_subprocess")
                .processInstanceBusinessKey("businessKey")
                .processInstanceVariableEquals("item", "item1")
                .correlate();
    }

Can you help me ?
I don’t understand if i’m doing something wrong or if it is a bug.
Thanks

multiple_instance.bpmn (6.1 KB)

2

Hi, Welcome to the Community.

Can you show me what code you’re using to actually trigger the message event? (i.e. how you’re sending the message) ?

3

In my project, camunda is embedded in a spring boot rest service.
“Production” code is quite similar than the code provided in my reproducers.

It looks like

@Service
public class CamundaService {

    private ProcessEngine processEngine;

    public void executeCorrelation(
            String eventMessage, String businessKey, String correlationKey, String correlationValue) {

        Map<String, Object> correlationKeys = new HashMap<>();
        correlationKeysMap.put(correlationKey, correlationValue);

        processEngine
                .getRuntimeService()
                .correlateMessage(
                        eventMessage,
                        businessKey,
                        correlationKeys ,
                        null
                );
    }

}

It seems that camunda ignores correlationKeys => if there are more than on subprocess instance, camunda throws the error i gave in my first message (it works if there is only one subprocess instance).

Thanks for your reply

4

You’re using an older method for sending messages.
Try something like this

       runtimeService.createMessageCorrelation("MessageName")
                .processInstanceBusinessKey("key")
                .localVariableEquals("item", "ItemValue")
                .correlate();
5

I’ve updated my junit as you proposed.
Unfortunately it still doesn’t work.

However, error is now different :

Cannot correlate message ‘message_for_subprocess’: No process definition or execution matches the parameters

@Test
    public void reproducer3() {
        List<String> items = Arrays.asList("item1", "item2", "items3");

        ProcessInstance processInstance = BpmnAwareTests
                .runtimeService()
                .createProcessInstanceByKey("multiplie_instance_problem")
                .businessKey("businessKey")
                .setVariableLocal("items", items)
                .execute();

        BpmnAwareTests
                .runtimeService()
                .createMessageCorrelation("message_for_subprocess")
                .processInstanceBusinessKey("businessKey")
                .localVariableEquals("item", "item1")
                .correlate();
    }

As expected, three subprocess instances are well created but a correlation with a specific instance cannot be achieved.

Can something be missing in bpmn ?

6

Can you run an assert to check to make sure that the engine is actually waiting for the message to come in?

7

Assert on the event id is true

        BpmnAwareTests
                .assertThat(processInstance)
                .isWaitingAt("event_for_subprocess");

If I set a bad value

        BpmnAwareTests
                .assertThat(processInstance)
                .isWaitingAt("bad_event_id");

error message is :

java.lang.AssertionError: Expecting ProcessInstance {id=‘9’, processDefinitionId=‘multiplie_instance_problem:2:7’, businessKey=‘businessKey’} to be waiting at [bad_event_id], but it is actually waiting at [event_for_subprocess, event_for_subprocess, event_for_subprocess].

As expected, we see that three instances are waiting to be correlated.

8

I’ve just noticed that you’re creating the list variable as “local” when you create the instance. It should be a regular variable.
The variables become local per instance of the list. not the list itself, so try that and see how it goes

9

Same error :frowning:

Cannot correlate message ‘message_for_subprocess’: No process definition or execution matches the parameters

    @Test
    public void reproducer3() {
        List<String> items = Arrays.asList("item1", "item2", "items3");

        ProcessInstance processInstance = BpmnAwareTests
                .runtimeService()
                .createProcessInstanceByKey("multiplie_instance_problem")
                .businessKey("businessKey")
                .setVariable("items", items)
                .execute();

        BpmnAwareTests
                .runtimeService()
                .createMessageCorrelation("message_for_subprocess")
                .processInstanceBusinessKey("businessKey")
                .localVariableEquals("item", "item1")
                .correlate();
    }
10

Here is a sample spring boot maven projet reproducing the problem : github project

A REST webservice with camunda embedded/h2 database is available.
Two junit classes (one doing REST calls, the other using BpmnAwareTests) are also available to reproduce the problem.

I don’t understand why i can’t correlate a specific subprocess instance.
The problem also exists with a sequential multiple instances subprocess.

11

It’s working with a “call activity” task.
Can someone explain why it doesn’t work with one bpmn file ?

12