Event Dispatcher

Events are a core concept of event sourcing, but they are useful outside it as well. Dispatching events allow you to decouple systems. Much of the tools that EventSauce is built on can be used to do just that.

When events are dispatched and stored in EventSauce, they are contained in a Message object. This object contains the event and any additional metadata. In order to simplify the dispatching of events in a non-eventsourced context, there is an EventDispatcher.

The default implementation of the EventDispatcher interface is the MessageDispatchingEventDispatcher. As the name suggests, this dispatcher allows you to dispatch events. These events are wrapped in a message, decorated, and dispatched to a MessageDispatcher of your choice.

Example usage:

<?php

use EventSauce\EventSourcing\Header;
use EventSauce\EventSourcing\MessageDispatchingEventDispatcher;

$eventDispatcher = new MessageDispatchingEventDispatcher(
    $yourMessageDispatcher,
    /* optional */ $yourMessageDecorator
);

$eventDispatcher->dispatch(
    new SomethingImportantHappened(),
    new SomeOtherThingHappened(),
);

$eventDispatcher->dispatchWithHeaders(
    [Header::AGGREGATE_ROOT_ID => $aggregateRootId->toString()],
    new SomethingImportantHappened(),
    new SomeOtherThingHappened(),
);