Akka examples in Java

A few examples using Akka with Java. These examples have basic structures in common:

All examples are runnable from within your IDE, by executing the Main method in the corresponding org.royrusso.app.System class.

Simple Akka Example

/simple :: The simplest of Akka examples. Creates an Actor that processes a command.

Akka Parent-Child Actors

/parent-child :: This example illustrates how you can configure an Akka cluster for hierarchical Actor relationships. This cluster contains Parent Actors that, given a Command, send an Event to a Child Actor for processing.

Akka Persistence with EventSourcing

/eventsourcing-persistence :: Usage of the new Akka Persistence module with Event Sourcing. An Akka Processor is responsible for processing non-persistent Commands that generate Events. The Events are persisted, and then allowed to modify the state of the processor. Additionally, the events are broadcast over the eventstream.

During recovery, the system then loads the persisted Events and replays them to the processor.

On restart, the system will load its last known state from the latest Snapshot (snapshot dir), and replay all Journaled (journal dir) Events after that point.

Notes:

Akka Persistent Channels

persistent-channel :: Illustrates how to send/receive payloads between actors listening on a channel. Messages are persisted until there is a valid confirmation of it being received by the destination Actor, and then deleted. This example also illustrates how the destination Actor may respond with an ack.

Akka Event-Bus

/event-bus :: Here we show how the Akka EventStream can be used by Actors that are subscribed to listen for certain event types that are emitted by another actor.