How to set global process variables in Camunda-BPM?

Question

I have a simple bpmn process in which i am using 2 service task,I am executing my process by using processEngine.getRuntimeService().startProcessInstanceByKey("Process_1", variables); where my variables is as follows:

Map variables = new HashMap();
variables.put("a", 2);
variables.put("b", 5);

Service task 1 implements an Addition java class and service task 2 implements a Multiplication class.

Now I want to have 3 variables (constants) c = 5, d = 10, e = 2 so that I can use c for service task 1 such that in Addition I can use this variable, similarly I want to use d in my Multiplication class, and e should be global so that I can use it in both classes.

Can anyone guide me on this?

Answer 1

As a quick fix you could include a Setup-Service Task as the first Task of the process which prefills your process-variables. Depending on how you start a process you could either: Set the Variables via the java-object-api

https://docs.camunda.org/manual/7.5/user-guide/process-engine/variables/#java-object-api

or you if you use a REST call you can provide these fixed values within the request body:

https://docs.camunda.org/manual/7.5/reference/rest/process-definition/post-start-process-instance/

Another simple solution would be a class with static values or a enum holding the needed values.

--edit--

if you want to use the inputOutput extension add something like this to your bpmn file:

<bpmn:process id="Process_1" isExecutable="false">
  <bpmn:extensionElements>
    <camunda:inputOutput>
      <camunda:inputParameter name="c">5</camunda:inputParameter>
      <camunda:inputParameter name="d">10</camunda:inputParameter>
      <camunda:inputParameter name="e">2</camunda:inputParameter>
    </camunda:inputOutput>
  </bpmn:extensionElements>

this can't be done in the diagram view of the camunda modeler, just switch to the XML representation of the process and add the extensionElement.