Compile this with plantuml activities.uml

@startuml

[*] --> created : init()

created : - Add optional parameters before starting

created -down-> starting : start()  

starting : - Adding more parameters is invalid
starting : - May not be running (eg, a Comm needs both\n  the sender and receiver to start)

starting -[dotted]down-> running : fired automatically by activity\nvetoable by observers

running : **Simulation Mode** (regular performance simulation)
running : Each activity is given a amount of work at creation,\n  that decreases with time according to the power of resources\n  and the sharing of resources amongst activities.
running : **Verification Mode** (model-checking)
running : Exhaustively test all orders of activity completion amongst running ones.

running -[dashed]-> done : . fired by performance models or by checker

done : - Destroyed only when refcount becomes 0
done : - The outcome of an activity will not change once it's done

done --> [*]

created --> CancelError : cancel()
starting -left-> CancelError : cancel()
running --> CancelError : cancel()
CancelError : Error: The user canceled that activity

created -[dashed]-> FailureError : may be fired by models 
starting -[dashed]right-> FailureError
running -[dashed]-> FailureError
FailureError : Error: one of the used resource failed

starting -[dashed]-> TimeoutError
running -[dashed]right-> TimeoutError
TimeoutError: Error: the specified timeout elapsed before completion
TimeoutError: May be surprising if timeout given by another involved actors

@enduml