Modelling
Messaging and Ecotone In Depth
Event Sourcing
Event Sourcing PHP
Ecotone comes with Prooph Event Store integration. This is well known and stable solution providing event storage over databases like Postgres, MySQL or MariaDB.
Ecotone provides Event Sourced Aggregates, which are stored as series of events.
Thanks to that we will be able to have the whole history of what happened with specific Aggregate.
And build up projections, that targets specific view, in order to keep our code simple, even with really complicated queries. This divide Commands from Queries (CQRS). Installation
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composer require ecotone/pdo-event-sourcing
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Ecotone Event Sourcing is based on well known and stable Prooph's Event Store.
It does provide support for three databases:
- PostgreSQL
- MySQL
- MariaDB
Storing Events in streams using Aggregates
There are two ways, we can make use of Event Sourced Aggregates.
Pure Event Sourced Aggregate
This way of handling events does allow for pure functions. Writes are clearly separated from writes.
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#[EventSourcingAggregate] // 1
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class Ticket
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{
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use WithAggregateVersioning; // 2
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​
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#[AggregateIdentifier] // 1
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private string $ticketId;
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private string $ticketType;
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​
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#[CommandHandler] // 2
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public static function register(RegisterTicket $command) : array
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{
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return [new TicketWasRegistered($command->getTicketId(), $command->getTicketType())];
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}
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​
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#[CommandHandler] // 2
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public function close(CloseTicket $command) : array
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{
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return [new TicketWasClosed($this->ticketId)];
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}
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​
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#[EventSourcingHandler] // 4
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public function applyTicketWasRegistered(TicketWasRegistered $event) : void
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{
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$this->ticketId = $event->getTicketId();
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$this->ticketType = $event->getTicketType();
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}
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}
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- 1.
- 2.Event Sourced Aggregate must provide version. You may leave it to
EcotoneusingWithAggregateVersioningor you can implement it yourself. - 3.
CommandHandlerfor event sourcing returns events generated by specific method. This will be passed to theRepositoryto be stored. - 4.
EventSourcingHandleris method responsible for reconstructingAggregatefrom previously created events. At least one event need to be handled in order to provideAggregateIdentifier.
Internal Recorder Aggregate
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#[EventSourcingAggregate(true)] // 1
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class Basket
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{
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use WithAggregateEvents;
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use WithAggregateVersioning;
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​
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#[AggregateIdentifier]
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private string $id;
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​
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#[CommandHandler] // 2
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public static function create(CreateBasket $command) : static
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{
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$basket = new static();
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$basket->recordThat(new BasketWasCreated($command->getId()));
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​
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return $basket;
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}
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​
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#[CommandHandler] // 2
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public function addProduct(AddProduct $command) : void
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{
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$this->recordThat(new ProductWasAddedToBasket($this->id, $command->getProductName()));
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}
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​
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#[EventSourcingHandler]
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public function applyBasketWasCreated(BasketWasCreated $basketWasCreated)
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{
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$this->id = $basketWasCreated->getId();
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}
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}
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- 1.In order to make use of alternative way of handling events, we need to set attribute to true
EventSourcingAggregate(true) - 2.Command Handlers instead of returning events are acting the same as State Stored Aggregates. All events which will be published using
recordThatwill be passed to theRepositoryto be stored.
Last modified 17d ago
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