CQRS - ES - Broadway sample

Cqrs Es with Broadway

Applying Broadway

• Event Domain

  • Create Event Domain class (UserWasCreated)
  • Class implements Broadway\Serializer\Serializable
  • Add 2 methods to deal this event:
    • Serialize => return array
    • Deserialize => return Event Domain object

• Model:

  • Create User Class with attributes and methods
    • Extends from Broadway\EventSourcing\EventSourcedAggregateRoot
  • Add getAggregateRootId method with Aggregate Root Id
  • Add create factory function with functionality:
    • Create User instance
    • Call apply function with Event Domain instance filled
  • Add applyNameEventDomain protected function
    • Get information from Event Domain
    • Fill User object with data

• Migration:

  • Add a new migration to create Event table (Version20220317233829)

• Command Handler:

  • Call to create User model function
  • Call to userStore repository to store the event

• Repository:

  • Create UserStoreRepository to store User events
  • Repository extends Broadway\EventSourcing\EventSourcingRepository
  • Create 2 functions:
    • Store => store User event
    • Get => get User event

• Read Model and Projection:

  • Read Model

    • Create UserView Model (copy methods and attributes from User model)
      • Extends Broadway\ReadModel\SerializableReadModel
      • Create constructor
      • Add serialize and deserialize function (in this case, similar to User model)
      • Add getId to return UserId (method required by SerializableReadModel)

  • Projection

    • Create UserProjection class
      • Listening Event Domains configured into this class
      • Extends from Broadway\ReadModel\Projector
      • It has, for each event, one function with the name applyNameEventDomain (UserWasCreated)
        • Receive UserWasCreated parameter/event
        • Call UserRepository to save UserView with Doctrine into database

  • Repository

    • Create a standard UserRepository with save function to store UserView model

• Process manager:

  • Sync:

    • Create DomainEventHandler to catch all events executed in Broadway event bus.
      • Implements Broadway\EventHandling\EventListener to catch events
    • Create SendWelcomeEmailProcessManager with Domain Event as parameter (UserWasCreated) to send an email

  • Async:

    • Add in DomainEventHandler implementation of MessageSubscriberInterface to catch all events published in named queued "events".
      • Implements Symfony\Component\Messenger\Handler\MessageSubscriberInterface to catch events
      • Add getHandledMessages method to get events from queue "events"
      • Add __invoke method to send this event to Symfony event bus
    • Create DomainEventPublisher to dispatch Asynchronous messages to RabbitMQ
      • Implements EventListener to catch Broadway events and save in array message variable (in memory)
      • Implements EventSubscriberInterface necessary to catch kernel events.
        • Create getSubscribedEvents to listen for the TERMINATE event to ensure that the event has been persisted.
        • Create publish method to dispatch event in RabbitMQ.
    • Create MessengerAsyncEventBus where configure async event bus and send message.

• Recovery data:

  • If user table is truncated, it is possible to recovery all data across events stored.
    • Create RestoreUserCommand to call Replayer class to execute events
    • Create Replayer class where implements EventVisitor
      • replayForEvent method is called all events by type to recovery events.
      • Then, doWithEvent method is called with each event to restore

Execution

Create a user storing event when user was created and saving in User MySql table

Commands:

• Database container: cd docker && make
• Create database structure: bin/console doctrine:migrations:migrate
• Execute project: make local
• Execute consumer: bin/console messenger:consume events -vv

Postman

Import this curl to Postman application and execute:

curl  --location --request POST 'https://localhost:8000/signup' \
      --header 'Content-Type: application/json' \
      --form '_name="Victor"' \
      --form '_email="[email protected]"' \
      --form '_password="password123"'