How do I implement wait for a service task execution

Camunda 7 Topics Discussion & Questions
1

Hi ,

Can anyone please advice how to wait for a service task execution to get complete.
The service task which I trigger is complex and would take several seconds to complete and give me a response which is to be forwarded to the next service task.

Best Regards,
Albin

2

How are you implementing the service task? Java Class or External Task?

default behavior would be that the process would wait for the task to be completed before moving on - what are you experiencing?

3

Thanks @Niall for the quick response.
My service task is a microservice which I am invoking using camunda connector.

<serviceTask id="step2" name="Service Task1">
  <extensionElements>
    <camunda:connector>
      <camunda:connectorId>http-connector</camunda:connectorId>
      <camunda:inputOutput>
        <camunda:inputParameter name="url">http://localhost:8081/test</camunda:inputParameter>
        <camunda:inputParameter name="method">POST</camunda:inputParameter>
        <camunda:inputParameter name="headers">
          <camunda:map>
            <camunda:entry key="Accept">application/json</camunda:entry>
          </camunda:map>
        </camunda:inputParameter>
        <camunda:inputParameter name="payload">
          <camunda:script scriptFormat="Javascript">**payload****

<camunda:outputParameter name=“Result”>
<camunda:script scriptFormat=“Javascript”>S(response).prop(‘key’).value()</camunda:script>

The microservice itself has some complex scenarios (and connections to other services) is in itself has wait methods written.
So I was wondering whether I need to write delay time in the bpmn so the execution waits for the response to be fetched.

4

Bascially your call is going to wait for as long as it takes to get a response from the rest call or it times out.
If you’re doing something that requires a longer waiting time then i would suggest that you don’t use a connector at all. I would suggest an External Task pattern. That way you don’t need to worry about upstream services taking too long.

2 Likes
5

Thankyou @Niall ,

Would it be possible to create an external service task which is a microservice.
How would i call the microservice in bpmn without the connector?
please advice.

Thanks and Regards,
Albin

6

External tasks are primarily used for microservice architecture. So it would suit you much better.
It might be useful to watch this tutorial to see how its intended to work.

1 Like
7

Thanks @Niall ,
Can i have a sequence of external tasks in which the next external task depends on the output of the previous one.

Regards,
Albin

8

Yes - when an external task uses the fetch and lock method it can ask for the process variables of the process. These variables could have been produced by another task.

9