@startuml
actor User1
database System
actor User2

group Waitlist
    group pain assessment
        System -> User1: Pain questions request
        System -> User2: Pain questions request
        ...
        User1 -> System: Completes pain questions
        User2 -> System: Completes pain questions
    end
    group experiment
        User1 <- System: Prayer Request
        ...
        User1 --> User2: Prays
    end
end

newpage

group Active
    group pain assessment
        System -> User1: Pain questions request
        System -> User2: Pain questions request
        ...
        User1 -> System: Completes pain questions
        User2 -> System: Completes pain questions
    end
    group experiment
        User1 <- System: Prayer Request
        User2 <- System: Prayer Request
        User1 --> User2: Prays
        System -> User2: Notifies prayed for
        User2 --> User1: Prays
        System -> User1: Notifies prayed for
        note over of System #aqua
        Notifications do not depend on the order in which User1 and User2 pray.
        The notification happens as soon as the prayer is recorded.
        end note
    end
end


@enduml