Best practise to update process variables with external data

Camunda 7 Topics Discussion & Questions
1

Hi,

we have an external system that saves some data which has to be updated in my process when it is edited in the external system.
I thought I could handle this via the tasklistener (assignment event). But it is possible that someone claims a user task and works on it a few days later, so the data could be old again.

What I need is to look after new data in the external system at the moment, when a user clicks on the task in his tasklist.

grafik
grafik929×375 54.6 KB

Is there any event or something where I can do that? If not, have you got an idea how I can handle this situation?

Thank you a lot
Nicole

2

Hello @NickiMueller,
You could use an event based subprocess with a non-interrupting message start event. The message is being sent from your UI and triggers the variables value update. These values then can be loaded by the task form.

https://camunda.com/best-practices/building-flexibility-into-bpmn-models/#_event_sub_processes

Best, McAlm

1 Like
3

Hello @McAlm,
thank you for your idea. But it is not clear for me.

What do you mean with “triggered from the UI?”. Something like javascript ‘onload’?

But when I do this, how does the event subprocess know that it should be carried out?

Here is my example.
grafik
I want that the event subprocess is carried out when the user wants to work on task “Antrag ausfüllen”

“Antrag ausfüllen” has a form where I can fill in the javascript “onload”: grafik

And then? How das the event subprocess know that it should be carried out?

Thank you a lot for more explanation / examples.
Nicole

4

I think it’s supposed that the external system sends a request to your process which is then translated to the start event of the subprocess.

If the external system does not care about any processes then I’d probably use a timer start event. I.e. perform time based polling of the external data.

5

The client needs to trigger (send) an event to the backend. You can use some javascript to send a rest request to your backend application that correlates the message to your process instance.