getImplementation() returns null

Camunda 7 Topics Discussion & Questions
1

Hi there,

I’m currently working on a project, where I need to distinguish the different tasks and their respective implementations.It works if I try to retrieve the id or name with getId() / getName(), but this doesn’t work for the implementation.

Is there anything I need to consider in order to access this piece of information? And why does it work for the name/id? It doesn’t matter wether this is a service task, business rule task or any other task. Doesn’t work on any for me.

This is a JUnit test, where I try to validate the correctness of tasks, which unfortunatly does not work as intended.

Thanks and have a nice day
Sascha

2

Hi Sascha,

It is not clear to me what you want to achieve. Please try to be more precise in what you want to do.

  • What do you mean with distinguishing implementations?
  • You write about methods getId() and getName() - which classes do they belong to?
  • You say you tried some things already. What did you try? If you have some code already, it may be a good idea to post it.

Cheers,
Thorben

3

Hi Thorben,

thanks for responding. I already thought that my questions were too vague to answer precisely.
So I try my best to clear things up now.

First, I create a small model with just a startevent, a businessruletask and an endevent. I now wrote some code in order to validate the model, so e.g. if the implementation is “DelegateExpresseion” then I want the field “DelegateExpression” to reference a java class. Same applies for “DMN”, which needs to reference a “Decision Ref”. So these small rules should be able to validate a small model, but in order to decide which rules apply I need to know what kind of implementation a task has.

Now in my code I try to evaluate what kind of implementation a task (in this case a businessruletask) uses and tried it with the following lines:

  final BaseElement baseElement = element.getBaseElement();
  final BusinessRuleTask task = (BusinessRuleTask) baseElement;    
  if(task instanceof BusinessRuleTask && task.getImplementation().compareTo("##unspecified") == 0){

Whats happens is that task.getImplementation() always returns the string ##unspecified or null.

implementation#.PNG253×515 8.01 KB

I hope this clears things up. Cheers for any help
Sascha

4

Thanks for the clarification. Camunda modeler and engine don’t use the implementation attribute. I think you’ll have to check the camunda extension attributes directly, i.e. task.getCamundaClass() != null etc.

Cheers,
Thorben

5

I will try that and report back. I hope your hint will clear things up.

Thanks
Sascha

EDIT: getCamundaClass returns null unfortunatly. So what can I do in order to check the implementation field value?

6

Hi again,

unfortunatly nothing really seems to work within java. getCamundaClass() returns null, which makes the problem even harder. Any further hints how to check a given businessRuleTask?

Cheers,
Sascha

7

Hi Sascha,

Could you please upload a minimal executable test case to github? That makes it easier to give hints on your code.

Cheers,
Thorben

8

Hi Thorben,

I created a workaround, which makes use of DOM Elements for a given XML. If you´re interested I´ll give you the link to GitHub and maybe you´ll see what the use of this is.

Cheers,
Sascha