Understanding Human Task states
The human task itself usually has a complete life cycle itself as well. We will now shortly introduce this life cycle, as shown in the figure below. For more details, check out the WS-HumanTask specification.
Whenever a task is created, it starts in the "Created" stage. It usually automatically transfers to the "Ready" state, at which point the task will show up on the task list of all the actors that are allowed to execute the task.
If you have already assigned the task to one user (as in our example) then the Task will transition to the "Reserved" phase.
If you have not assigned the task to one actor, then the Task will stay in the "Ready" phase until an actor has claimed for it and then it will transition to the Reserved phase.
Once in the Reserved phase, the user can then at some point decide to start executing the task, in which case the task status is changed to "InProgress".
Finally, once the task has been performed, the user must complete the task (and can specify the result data related to the task), in which case the status is changed to "Completed"