Domain event bundle

Bundle to create the domain layer of your Domain-driven design (DDD) application.

This Symfony bundle is a wrapper for gpslab/domain-event, look it for more details.

Installation

Pretty simple with Composer, run:

composer req gpslab/domain-event-bundle

Configuration

Example configuration

gpslab_domain_event:
    # Event bus service
    # Support 'listener_located', 'queue' or a custom service
    # As a default used 'listener_located'
    bus: 'listener_located'

    # Event queue service
    # Support 'pull_memory', 'subscribe_executing' or a custom service
    # As a default used 'pull_memory'
    queue: 'pull_memory'

    # Event listener locator
    # Support 'symfony', 'container', 'direct_binding' or custom service
    # As a default used 'symfony'
    locator: 'symfony'

    # Publish domain events post a Doctrine flush event
    # As a default used 'false'
    publish_on_flush: true

Usage

Create a domain event

use GpsLab\Domain\Event\Event

class PurchaseOrderCreatedEvent implements Event
{
    private $customer_id;
    private $create_at;

    public function __construct(CustomerId $customer_id, \DateTimeImmutable $create_at)
    {
        $this->customer_id = $customer_id;
        $this->create_at = $create_at;
    }

    public function customerId(): CustomerId
    {
        return $this->customer_id;
    }

    public function createAt(): \DateTimeImmutable
    {
        return $this->create_at;
    }
}

Raise your event

use GpsLab\Domain\Event\Aggregator\AbstractAggregateEvents;

final class PurchaseOrder extends AbstractAggregateEvents
{
    private $customer_id;
    private $create_at;

    public function __construct(CustomerId $customer_id)
    {
        $this->customer_id = $customer_id;
        $this->create_at = new \DateTimeImmutable();

        $this->raise(new PurchaseOrderCreatedEvent($customer_id, $this->create_at));
    }
}

Create listener

use GpsLab\Domain\Event\Event;

class SendEmailOnPurchaseOrderCreated
{
    private $mailer;

    public function __construct(\Swift_Mailer $mailer)
    {
        $this->mailer = $mailer;
    }

    public function onPurchaseOrderCreated(PurchaseOrderCreatedEvent $event): void
    {
        $message = $this->mailer
            ->createMessage()
            ->setTo('[email protected]')
            ->setBody(sprintf(
                'Purchase order created at %s for customer #%s',
                $event->createAt()->format('Y-m-d'),
                $event->customerId()
            ));

        $this->mailer->send($message);
    }
}

services:
    SendEmailOnPurchaseOrderCreated:
        arguments: [ '@mailer' ]
        tags:
            - { name: domain_event.listener, event: PurchaseOrderCreatedEvent, method: onPurchaseOrderCreated }

Publish events in listener

use GpsLab\Domain\Event\Bus\EventBus;

// get event bus from DI container
$bus = $this->get(EventBus::class);

// do what you need to do on your Domain
$purchase_order = new PurchaseOrder(new CustomerId(1));

// this will clear the list of event in your AggregateEvents so an Event is trigger only once
$events = $purchase_order->pullEvents();

// You can have more than one event at a time.
foreach($events as $event) {
    $bus->publish($event);
}

// You can use one method
//$bus->pullAndPublish($purchase_order);

Listener method name

You do not need to specify the name of the event handler method. By default, the __invoke method is used.

use GpsLab\Domain\Event\Event;

class SendEmailOnPurchaseOrderCreated
{
    private $mailer;

    public function __construct(\Swift_Mailer $mailer)
    {
        $this->mailer = $mailer;
    }

    public function __invoke(PurchaseOrderCreatedEvent $event): void
    {
        $message = $this->mailer
            ->createMessage()
            ->setTo('[email protected]')
            ->setBody(sprintf(
                'Purchase order created at %s for customer #%s',
                $event->createAt()->format('Y-m-d'),
                $event->customerId()
            ));

        $this->mailer->send($message);
    }
}

services:
    SendEmailOnPurchaseOrderCreated:
        arguments: [ '@mailer' ]
        tags:
            - { name: domain_event.listener, event: PurchaseOrderCreatedEvent }

Event subscribers

Create subscriber

use GpsLab\Domain\Event\Event;
use GpsLab\Domain\Event\Listener\Subscriber;

class SendEmailOnPurchaseOrderCreated implements Subscriber
{
    private $mailer;

    public function __construct(\Swift_Mailer $mailer)
    {
        $this->mailer = $mailer;
    }

    public static function subscribedEvents(): array
    {
        return [
            PurchaseOrderCreatedEvent::class => ['onPurchaseOrderCreated'],
        ];
    }

    public function onPurchaseOrderCreated(PurchaseOrderCreatedEvent $event): void
    {
        $message = $this->mailer
            ->createMessage()
            ->setTo('[email protected]')
            ->setBody(sprintf(
                'Purchase order created at %s for customer #%s',
                $event->createAt()->format('Y-m-d'),
                $event->customerId()
            ));

        $this->mailer->send($message);
    }
}

services:
    SendEmailOnPurchaseOrderCreated:
        arguments: [ '@mailer' ]
        tags:
            - { name: domain_event.subscriber }

Use pull Predis queue

Install Predis with Composer, run:

composer require predis/predis

services:
    # Predis
    Predis\Client:
        arguments: [ '127.0.0.1' ]

    # Events serializer for queue
    GpsLab\Domain\Event\Queue\Serializer\SymfonySerializer:
        arguments: [ '@serializer', 'json' ]

    # Predis event queue
    GpsLab\Domain\Event\Queue\Pull\PredisPullEventQueue:
        arguments:
            - '@Predis\Client'
            - '@GpsLab\Domain\Event\Queue\Serializer\SymfonySerializer'
            - '@logger'
            - 'event_queue_name'

Change config for use custom queue:

gpslab_domain_event:
    queue: 'GpsLab\Domain\Event\Queue\Pull\PredisPullEventQueue'

And now you can use custom queue:

use GpsLab\Domain\Event\Queue\EventQueue;

$container->get(EventQueue::class)->publish($domain_event);

In latter pull events from queue:

use GpsLab\Domain\Event\Queue\EventQueue;

$queue = $container->get(EventQueue::class);
$bus = $container->get(EventQueue::class);

while ($event = $queue->pull()) {
    $bus->publish($event);
}

Use Predis subscribe queue

Install Predis PubSub adapter with Composer, run:

composer require superbalist/php-pubsub-redis

services:
    # Predis
    Predis\Client:
        arguments: [ '127.0.0.1' ]

    # Predis PubSub adapter
    Superbalist\PubSub\Redis\RedisPubSubAdapter:
        arguments: [ '@Predis\Client' ]

    # Events serializer for queue
    GpsLab\Domain\Event\Queue\Serializer\SymfonySerializer:
        arguments: [ '@serializer', 'json' ]

    # Predis event queue
    GpsLab\Domain\Event\Queue\Subscribe\PredisSubscribeEventQueue:
        arguments:
            - '@Superbalist\PubSub\Redis\RedisPubSubAdapter'
            - '@GpsLab\Domain\Event\Queue\Serializer\SymfonySerializer'
            - '@logger'
            - 'event_queue_name'

Change config for use custom queue:

gpslab_domain_event:
    queue: 'GpsLab\Domain\Event\Queue\Subscribe\PredisSubscribeEventQueue'

And now you can use custom queue:

use GpsLab\Domain\Event\Queue\EventQueue;

$container->get(EventQueue::class)->publish($domain_event);

Subscribe on the queue:

use GpsLab\Domain\Event\Queue\EventQueue;

$container->get(EventQueue::class)->subscribe(function (Event $event) {
    // do somthing
});

Note

You can use subscribe handlers as a services and tag it for optimize register.

Many queues

You can use many queues for separation the flows. For example, you want to handle events of different Bounded Contexts separately from each other.

services:
    acme.domain.purchase_order.event.queue:
        class: GpsLab\Domain\Event\Queue\Pull\PredisPullEventQueue
        arguments:
            - '@Superbalist\PubSub\Redis\RedisPubSubAdapter'
            - '@GpsLab\Domain\Event\Queue\Serializer\SymfonySerializer'
            - '@logger'
            - 'purchase_order_event_queue'

    acme.domain.article_comment.event.queue:
        class: GpsLab\Domain\Event\Queue\Pull\PredisPullEventQueue
        arguments:
            - '@Superbalist\PubSub\Redis\RedisPubSubAdapter'
            - '@GpsLab\Domain\Event\Queue\Serializer\SymfonySerializer'
            - '@logger'
            - 'article_comment_event_queue'

And now you can use a different queues.

In Purchase order Bounded Contexts.

$event = new PurchaseOrderCreatedEvent(
    new CustomerId(1),
    new \DateTimeImmutable()
);

$container->get('acme.domain.purchase_order.event.queue')->publish($event);

In Article comment Bounded Contexts.

$event = new ArticleCommentedEvent(
    new ArticleId(1),
    new AuthorId(1),
    $comment
    new \DateTimeImmutable()
);

$container->get('acme.domain.article_comment.event.queue')->publish($event);

Note

Similarly, you can split the subscribe queues.

License

This bundle is under the MIT license. See the complete license in the file: LICENSE

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