Support undefined tasks

[saig0]

Is your feature request related to a problem? Please describe.
When I start modeling a process, I don't define the types of tasks (i.e. service task, user task, etc.). Initially, all tasks are undefined, also called abstract tasks. Later in the modeling, I will define the types task-by-task.

But I can't deploy my process until all tasks have a supported type.

Describe the solution you'd like

I can deploy a process that contains undefined tasks. For example, the following process:

I can create an instance of this process. The process instance can activate and complete the undefined tasks in a pass-through semantic. So, the task is activated and immediately completed without additional logic. Similar to manual tasks.

Describe alternatives you've considered
I use manual tasks instead of undefined tasks. So, I can deploy and execute my process. But on the modeling, I need additional clicks for each task.

Additional context
The undefined task should behave exactly like a manual task.

(BPMN 2.0, chapter 13.2.3, page 430)

New contributors could watch the video on how to implement a new BPMN symbol.

[nikku]

Is there any operational differences between manual and abstract tasks?

[nikku]

Did you already settle on a naming? If not I'd encourage you to call this thing undefined task. This would mirror how we call it in our modeling tools. We can obviously decide to move to "abstract task" as a name. Our research (conducted in the past by @andreasgeier, I cannot find a reference right now) revealed that there is no clear winner in terms of naming (abstract vs. undefined vs. blank).

[remcowesterhoud]

That's a valid topic. I was following the BPMN spec where they refer to it as Abstract Task. But if we tend to call it an Undefined Task in other places we should align on that. I think Undefined Task is a bit more descriptive as well. What are your thoughts @saig0?

[saig0]

I like "undefined task". Let's go for it. 👍

[remcowesterhoud]

Is there any operational differences between manual and abstract tasks?

@nikku Sorry, I missed this question earlier. There is no operational difference between the two of them.

[christian-konrad]

Finally, this resolves soooo much pain, and actually allows us to say that we support "iterative modeling+implementation"!
It is also a huge accelerator for https://github.com/camunda/product-hub/issues/144 (the modeling-only use case), since it allows to start with a strategical model without being punished by 10s of error messages for undefined tasks once you switch to "implement" mode (to build the operational model).

[nikku]

Agreed upon the name (2022-10-12, #10562 (comment), #10562 (comment)): We call it Undefined Task.