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Symfony bridge for Event Sourcing and CQRS

Library providing interfaces and implementations for event-sourced applications for Symfony Applications.

This package is the symfony adapter of Neos.EventSourcing (which was created for the Neos/Flow framework).

Demo

Check out the Symfony Demo Repository:

https://github.com/Inchie/symfony-eventsourcing-demo.git

Getting started

In your symfony application, install this package and neos/event-sourcing via composer:

Setting up a Doctrine Event Store

Since there could be multiple Event Stores simultaneously in one application, this package comes without a pre-configured "default" store. It is just a matter of a couple of lines of YAML to configure a custom store:

config/packages/neos_eventsourcing.yaml:

Set the charset in the doctrine config to utf8mb4 by adding the following lines.

config/packages/doctrine.yaml:

Add the following to bundles.php:

To make use of the newly configured Event Store one more step is required in order to finish the setup (in this case to create the corresponding database table):

Writing events

Reading events

Reacting to events

In order to react upon new events you'll need an event listener:

The when*() methods of classes implementing the EventSubscriberInterface and ProjectorInterface will be invoked whenever a corresponding event is committed to the Event Store.

NOTE!!! You always have to use "when*" namings, as otherwise, the EventListenerInvoker will not properly call the right methods here (see https://github.com/neos/Neos.EventSourcing/issues/282)

Replay projection

With the following command you can rebuild a projection.

Events & event listeners

The Neos EventSourcing package comes with its own events and event listeners implementation. We cannot use this implementation for several reasons in the symfony context.

To get the listeners (subscribers in symfony) for an event we call the symfony event dispatcher (in the SymfonyEventPublisher).

The listeners are handled by the InternalCatchUpEventListenerCommand. This command uses the (Neos EventSourcing) EventListenerInvoker to call the listeners method name.

The specialty about this is that the EventSourcing package uses the "when" namings. For that reason the listeners method names have to start with when prefix too (@see Reacting to events).

All configuration options in neos_eventsourcing.yml

• stores
  • [name of event store]
  • eventTableName: database table name to use as event storage (required)
  • storage: which storage engine to use for persisting events. A class name, by default: Neos\EventSourcing\EventStore\Storage\Doctrine\DoctrineEventStorage
  • eventPublisherTransport: Class name. How the asychronity between event store and projection is implemented. By default, Neos\EventSourcing\SymfonyBridge\Transport\ConsoleCommandTransport is used, but also Neos\EventSourcing\SymfonyBridge\Transport\MessengerTransport is possible.

Internal Implementation

How is this package constructed? We try to give an overview here:

composer.json

We replace neos/flow and flowpack/jobqueue-common to ensure these are not installed.