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

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

Interface Decider<COMMAND,EVENT,ERROR,STATE>

Type Parameters:

COMMAND - The type of Commands that the Handler.handle(Object, Object) can process

EVENT - The type of Events that can be returned by Handler.handle(Object, Object) and applied in the StateEvolver.applyEvent(Object, Object)

ERROR - The type of Error that can be returned by the Handler.handle(Object, Object) method

STATE - The type of Aggregate State that this Decider works with in Handler.handle(Object, Object), InitialStateProvider.initialState(), StateEvolver.applyEvent(Object, Object) and isFinal(Object)

All Superinterfaces:

Handler<COMMAND,EVENT,ERROR,STATE>, InitialStateProvider<STATE>, IsStateFinalResolver<STATE>, StateEvolver<EVENT,STATE>

public interface Decider<COMMAND,EVENT,ERROR,STATE>
extends Handler<COMMAND,EVENT,ERROR,STATE>, StateEvolver<EVENT,STATE>, InitialStateProvider<STATE>, IsStateFinalResolver<STATE>

Variant of the event sourced Decider pattern, which supports building an Aggregate STATE based on previous EVENT's that relate to the aggregate instance, and which can handle COMMAND's, whose side effect is either an ERROR or a List of EVENT's (can be an empty list)

Method Summary

Modifier and Type	Method	Description
static <COMMAND,EVENT,ERROR,STATE> Decider<COMMAND,EVENT,ERROR,STATE>	decider(Handler<COMMAND,EVENT,ERROR,STATE> handler, InitialStateProvider<STATE> initialStateProvider, StateEvolver<EVENT,STATE> stateEvolver, IsStateFinalResolver<STATE> stateIsStateFinalResolver)	Factory method for creating a Decider instance from instances of the various Decider related interfaces
default boolean	isFinal(STATE state)	Return true from this method IF the aggregate's state is final and no more changes can occur, i.e.

Methods inherited from interface dk.cloudcreate.essentials.components.eventsourced.aggregates.decider.Handler

handle

Methods inherited from interface dk.cloudcreate.essentials.components.eventsourced.aggregates.decider.InitialStateProvider

initialState

Methods inherited from interface dk.cloudcreate.essentials.components.eventsourced.aggregates.decider.StateEvolver

applyEvent

Method Detail

decider

static <COMMAND,EVENT,ERROR,STATE> Decider<COMMAND,EVENT,ERROR,STATE> decider(Handler<COMMAND,EVENT,ERROR,STATE> handler,
                                                                                                                  InitialStateProvider<STATE> initialStateProvider,
                                                                                                                  StateEvolver<EVENT,STATE> stateEvolver,
                                                                                                                  IsStateFinalResolver<STATE> stateIsStateFinalResolver)

Factory method for creating a Decider instance from instances of the various Decider related interfaces

Type Parameters:

COMMAND - The type of Commands that the Handler.handle(Object, Object) can process

EVENT - The type of Events that can be returned by Handler.handle(Object, Object) and applied in the StateEvolver.applyEvent(Object, Object)

ERROR - The type of Error that can be returned by the Handler.handle(Object, Object) method

STATE - The type of Aggregate State that this Decider works with in Handler.handle(Object, Object), InitialStateProvider.initialState(), StateEvolver.applyEvent(Object, Object) and isFinal(Object)

Parameters:

handler - A Decider related interface that is responsible for handling COMMAND(s)

initialStateProvider - A Decider related interface, which provides the Initial STATE for a given aggregate.

stateEvolver - A Decider related interface, which can apply EVENT<(s) to an aggregate/i>'s STATE instance

stateIsStateFinalResolver - A Decider related interface that resolves if the aggregate's state is final and no more changes can occur, i.e. no more events can be persisted

Returns:

a Decider instance that delegates to the Decider related instances provided as parameters

isFinal

default boolean isFinal(STATE state)

Return true from this method IF the aggregate's state is final and no more changes can occur, i.e. no more events can be persisted (i.e. Handler.handle(Object, Object) will return an ERROR)
Note: This method is called isTerminal in the decider pattern
See IsStateFinalResolver.isFinal(Object) for more details.
The default implementation in the Decider always return false

Specified by:

isFinal in interface IsStateFinalResolver<COMMAND>

Parameters:

state - the current STATE of the aggregate

Returns:

true IF the aggregate's state is final, otherwise false