scaladsl

Type Members

1. trait Effect[+Event, State] extends AnyRef

   

   A command handler returns a Effect directive that defines what event or events, if any, to persist.

   A command handler returns a Effect directive that defines what event or events, if any, to persist. Use the thenPersist, thenPersistAll or done methods of the context that is passed to the command handler function to create the Effect directive.

   Additional side effects can be performed in the callback andThen

   Instances of Effect are available through factories in the respective Java and Scala DSL packages.

   Not intended for user extension.

   Annotations

   @DoNotInherit()

2. class EffectFactories[Command, Event, State] extends AnyRef

   

   Not intended for user extension.

   Not intended for user extension. Access an instance through ReplicatedEntity#Effect.

   Annotations

   @DoNotInherit()

3. abstract class ReplicatedEntity[Command, Event, State] extends InternalReplicatedEntity[Command, Event, State]

   

   A ReplicatedEntity has a stable entity identifier, with which it can be accessed from anywhere in the cluster.

   A ReplicatedEntity has a stable entity identifier, with which it can be accessed from anywhere in the cluster. It is run by an actor and the state is persistent using event sourcing.

   initialState and behavior are abstract methods that your concrete subclass must implement. The behavior is defined as a set of handlers given a state. The handlers are functions to process incoming commands.

   Persistent and replicated events are applied to the state with the eventHandler method.

   The ReplicatedEntity receives commands of type Command that can be validated before persisting state changes as events of type Event. The functions that process incoming commands are registered in the CommandHandler using onCommand of the CommandHandler.

   A command may also be read-only and only perform some side-effect, such as replying to the request. Such command handlers are registered using onReadOnlyCommand of the CommandHandler. Replies are sent with the sender() ActorRef in the context or an ActorRef that is passed in the command.

   A command handler returns a Effect directive that defines what event or events, if any, to persist. Use the thenPersist, thenPersistAll or done methods of the context that is passed to the command handler function to create the Effect directive.

   When an event has been persisted successfully the state of type State is updated by applying the event to the current state by invoking the eventHandler. The eventHandler returns the new state. The state must be immutable, so you return a new instance of the state. Current state is passed as parameter to the event handler. The same event handlers are also used when the entity is started up to recover its state from the stored events.

   After persisting an event, external side effects can be performed with the andThen function of the Effect directive. A typical side effect is to reply to the request to confirm that it was performed successfully. Replies are sent with the sender() ActorRef in the context or an ActorRef that is passed in the command.

   The event handlers are typically only updating the state, but they may also change the behavior of the entity in the sense that new functions for processing commands and events may be defined for a given state. This is useful when implementing finite state machine (FSM) like entities.

   When the entity is started the state is recovered by replaying stored events. To reduce this recovery time the entity may start the recovery from a snapshot of the state and then only replaying the events that were stored after the snapshot. Such snapshots are automatically saved after a configured number of persisted events.

   Command

   the super type of all commands

   Event

   the super type of all events

   State

   the type of the state

   Annotations

   @ApiMayChange()