how to get the list of all user tasks present in BPMN XML which is stored in the database.
Hey,
I am not sure exactly what you are trying to do? What have you tried until now?
I would advise you to have a look at the BpmnModel class. You can get a BpmnModel for a certain process definition id by going through RepositoryService#getBpmnModel(String).
You can the get the Process and use Process#findFlowElementsOfType(Class) where for class you would use the UserTask model.
Cheers,
Filip