Module dk.cloudcreate.essentials.components.eventsourced.aggregates
Package dk.cloudcreate.essentials.components.eventsourced.aggregates.decider

Interface StateEvolver<EVENT,​STATE>

  • Type Parameters:
    EVENT - The type of Events that can be applied in the applyEvent(Object, Object)
    STATE - The type of aggregate/projection/view STATE that applyEvent(Object, Object) supports
    All Known Subinterfaces:
    Decider<COMMAND,​EVENT,​ERROR,​STATE>, View<EVENT,​STATE>
    Functional Interface:
    This is a functional interface and can therefore be used as the assignment target for a lambda expression or method reference.
    @FunctionalInterface
public interface StateEvolver<EVENT,​STATE>
    A Decider or View related interface, which can apply EVENT<(s) to a aggregate/projection/view STATE instance

    • Method Summary

      All Methods Static Methods Instance Methods Abstract Methods 
      Modifier and Type Method Description
      STATE applyEvent​(EVENT event, STATE state)
      Apply the EVENT to the aggregate/projection/view STATE instance
      Note: This method is called evolve in the decider pattern
      static <STATE,​EVENT>
      STATE      		 applyEvents​(StateEvolver<EVENT,​STATE> stateEvolver, STATE initialState, Stream<EVENT> eventStream)
      Perform a left-fold over the eventStream using the initialState as the initial state

    • Method Detail

      • applyEvent

        STATE applyEvent​(EVENT event,
                 STATE state)
        Apply the EVENT to the aggregate/projection/view STATE instance
        Note: This method is called evolve in the decider pattern
        Parameters:
        event - the EVENT to be applied / projected onto the current aggregate/projection/view STATE
        state - the current STATE of the aggregate/projection/view
        Returns:
        the new aggregate/projection/view STATE (after the EVENT has been applied / projected onto the current aggregate/projection/view STATE)

      • applyEvents

        static <STATE,​EVENT> STATE applyEvents​(StateEvolver<EVENT,​STATE> stateEvolver,
                                             STATE initialState,
                                             Stream<EVENT> eventStream)
        Perform a left-fold over the eventStream using the initialState as the initial state
        Type Parameters:
        EVENT - The type of Events that can be applied in the applyEvent(Object, Object)
        STATE - The type of aggregate/projection/view STATE that applyEvent(Object, Object) supports
        Parameters:
        stateEvolver - the state evolver (that applies events to the state)
        initialState - the initial state provided to the state evolver
        eventStream - the stream of Events supplied one by one (in-order) to the state evolver
        Returns:
        the initial state with all events applied to it