Message Correlation function

Camunda 7 Topics Discussion & Questions
1

Hi everyone

when should we use
void correlateMessage(String messageName, String businessKey ?

what is the difference between this function and createMessageCorrelation() ?

2

Hi @mrdavoodi64 ,

createMessageCorrelation() is used to define a complex message correlation.
so you can build specific correlation logic as needed.

Below are two different variants constructed through createMessageCorrelation() method

runtimeService
  .createMessageCorrelation("myMessage") 
  .processInstanceBusinessKey(myMessage.getOrderId().toString()) 
  .correlate();

runtimeService
  .createMessageCorrelation('message_invoiceReceived') 
  .setVariable("invoiceId", "123456") 
  .correlate();

The above 1’st variant is equivalent to below call using correlateMessage method
correlateMessage("myMessage", myMessage.getOrderId().toString());

3

Thanks @hassang

but when I use the following expression in camunda modeler

${execution.getProcessEngineServices().getRuntimeService().correlateMessage(“myMessage”,“mybusinesskey”)}

I will get the following error:

“can not coerce from class java.lang.string to interface java.util.map”

4

Hi @mrdavoodi64,

Could you please share your model or the exact used expression

5

@hassang
yes this is my sample model

I used a static number “123456” as business key for testing purpose.diagram_1.bpmn (5.9 KB)

6

Hi @mrdavoodi64 ,

You have two issues in your model.

  • Message boundary event has the value of “myMessage” for message name whereas the value passed for messageName parameter of correlateMessage method is “MyMessage”

  • Both tasks (Task 1 & Task 2) are undefined tasks. Boundary event means that while the activity is running, the message boundary event is listening for named message but since Task 1 is undefined task then this will never happen since undefined task is considered as a pass-through activity.

Try below attached model in which Task 1 & Task 2 are set as User Tasks
diagram_1.bpmn (5.9 KB)

Notice: the model is valid only for testing purposes since completing Task 1 before Task 2 will lead to an error.

7

Hi @hassang
Thanks for your response, but the issue is still remained,

This is the error I get in the model that you have uploaded :

“can not coerce from class java.lang.string to interface java.util.map”

8

Hi @mrdavoodi64,

Have you supplied the value of “123456” as businessKey on process start?

Please try below scenario

  • Start a new process instance with the value “123456” supplied as businessKey.

  • Complete Task 2.

I have tried the above scenario and it worked perfectly.

9

The reason you get this error is because in general expression language doesn’t allow method overloading.
In RuntimeService.java there are the following methods
void correlateMessage(String messageName, String businessKey);
void correlateMessage(String messageName, Map<String, Object> correlationKeys);
So in your case it is picking the wrong method and trying to put the string into the correlateMessage which takes in the map

10

Thanks @matt

So in expression mode we can not use correlateMessage method?

the following expression works properly in expression mode:

${execution.getProcessEngineServices().getRuntimeService().createMessageCorrelation(“messageName”).processInstanceBusinessKey(“bskey”).correlate()}

11

If you are using these methods

correlateMessage(String messageName)
correlateMessage(String messageName, String businessKey, Map<String, Object> correlationKeys, Map<String, Object> processVariables)

then I’d say its ok, so long as they don’t implement a new correlateMessage method with 1 or 4 parameters. So for me I’d go with that last expression for createMessageCorrelation as it seems less likely to cause an issue.

1 Like
12

thanks @matt

13