Cosmos.EventSourcing.Abstractions 0.0.5

Cosmos.EventSourcing.Abstractions

Abstracciones base para implementar Event Sourcing y CQRS en .NET 10.

Descripción

Este paquete proporciona las abstracciones fundamentales necesarias para construir aplicaciones usando Event Sourcing y el patrón CQRS (Command Query Responsibility Segregation). Define interfaces y clases base que permiten una arquitectura desacoplada y testeable.

Características

Event Sourcing

• AggregateRoot: Clase base para agregados con manejo de eventos no confirmados
• IEventStore: Interfaz para persistir y recuperar agregados desde el event store

Command Side (CQRS)

• ICommandHandler<TCommand>: Handler síncrono para comandos sin retorno
• ICommandHandlerAsync<TCommand>: Handler asíncrono para comandos sin retorno
• ICommandHandler<TCommand, TResult>: Handler síncrono con valor de retorno
• ICommandHandlerAsync<TCommand, TResult>: Handler asíncrono con valor de retorno
• ICommandRouter: Router para invocar command handlers

Query Side (CQRS)

• IQueryHandler<TQuery, TResult>: Handler para consultas
• IQueryRouter: Router para invocar query handlers
• IProjectionStore: Almacén de proyecciones/vistas de lectura

Instalación

dotnet add package Cosmos.EventSourcing.Abstractions

Uso

Crear un Aggregate Root

using Cosmos.EventSourcing.Abstractions;

public class Order : AggregateRoot
{
    public List<OrderItem> Items { get; private set; } = new();
    public OrderStatus Status { get; private set; }

    public void AddItem(string productId, int quantity, decimal price)
    {
        var @event = new ItemAdded(Id, productId, quantity, price);
        Apply(@event);
        _uncommittedEvents.Add(@event);
    }

    private void Apply(ItemAdded @event)
    {
        Items.Add(new OrderItem(@event.ProductId, @event.Quantity, @event.Price));
    }
}

Implementar un Command Handler

using Cosmos.EventSourcing.Abstractions.Commands;

public record AddItemToOrder(string OrderId, string ProductId, int Quantity, decimal Price);

public class AddItemToOrderHandler : ICommandHandlerAsync<AddItemToOrder>
{
    private readonly IEventStore _eventStore;

    public AddItemToOrderHandler(IEventStore eventStore)
    {
        _eventStore = eventStore;
    }

    public async Task HandleAsync(AddItemToOrder command, CancellationToken cancellationToken)
    {
        var order = await _eventStore.GetAggregateRootAsync<Order>(
            command.OrderId,
            cancellationToken
        );

        order?.AddItem(command.ProductId, command.Quantity, command.Price);

        _eventStore.Save(order!);
        await _eventStore.SaveChangesAsync();
    }
}

Implementar un Query Handler

using Cosmos.EventSourcing.Abstractions.Queries;

public record GetOrderById(string OrderId);

public class GetOrderByIdHandler : IQueryHandler<GetOrderById, OrderDto?>
{
    private readonly IProjectionStore _projectionStore;

    public GetOrderByIdHandler(IProjectionStore projectionStore)
    {
        _projectionStore = projectionStore;
    }

    public async Task<OrderDto?> HandleAsync(GetOrderById query, CancellationToken cancellationToken)
    {
        return await _projectionStore.GetByIdAsync<OrderDto>(query.OrderId, cancellationToken);
    }
}

Usar el Command Router

public class OrderController
{
    private readonly ICommandRouter _commandRouter;

    public OrderController(ICommandRouter commandRouter)
    {
        _commandRouter = commandRouter;
    }

    public async Task<IActionResult> AddItem(AddItemRequest request)
    {
        var command = new AddItemToOrder(
            request.OrderId,
            request.ProductId,
            request.Quantity,
            request.Price
        );

        await _commandRouter.InvokeAsync(command, CancellationToken.None);

        return Ok();
    }
}

Patrones de Event Sourcing

Recuperar Agregados por Versión

// Obtener el estado actual
var order = await _eventStore.GetAggregateRootAsync<Order>("order-123", ct);

// Obtener el estado en una versión específica
var orderV5 = await _eventStore.GetAggregateRootAsync<Order>("order-123", version: 5, ct);

// Obtener el estado en un momento específico
var orderAtTime = await _eventStore.GetAggregateRootAsync<Order>(
    "order-123",
    DateTimeOffset.Parse("2024-01-15T10:00:00Z"),
    ct
);

Implementaciones Concretas

Este paquete solo contiene abstracciones. Para implementaciones listas para usar:

• Cosmos.EventSourcing.CritterStack: Implementaciones con Wolverine y Marten
• Cosmos.EventSourcing.Testing.Utilities: Utilidades para testing

Requisitos

• .NET 10.0 o superior

Dependencias

Sin dependencias externas (abstracciones puras).

Licencia

Copyright © Cosmos. Todos los derechos reservados.