Choosing when tasks can start and how to update its data?

[andregs]

Hi, guys. I have some requirements in my process that I don’t know how to implement in Activiti. Could you help me?

Suppose I have a process like this: Start -> Task A -> B -> C -> D -> E -> End.

While the process execution is between task B and task D, the user can start another task, F. He cannot start task F before task B is started, neither after task D is finished. When task D finishes, if task F weren't executed yet, it could not be executed anymore. How can I implement task F in Activiti?

Now suppose that task C, for example, could be executed many times. I mean, the user can finish task C by submitting a form (and that triggers task D), but after that he needs to fix/update some fields in that form. How can he do it?

Thanks for your help,

[jbarrez]

You will have to implement that yourself in your own business logic, which queries the process instance state to make the right judgdement.