Evento

This C# .Net Standard library can be used to build components based on Event Sourcing patterns. It can be considered a small toolbox as it provides few types and a Repository. The types are Command and Event and can help to better structure the flow of your data. It's lightweight and you can just copy and paste the code in your component codebase to avoid adding a dependency. In that way you can easily tailor made the features on your needs.

It is not related to a particular storage. There is a Repository implementation using EventStore https://github.com/EventStore/EventStore

You can find more info in my blog http://www.dinuzzo.co.uk/2017/04/28/domain-driven-design-event-sourcing-and-micro-services-explained-for-developers/

The 'Evento' library has no-dependencies therefore it can be referenced by Domain projects and Application Service projects. You can see a Sample project showing how to use this library https://github.com/riccardone/Evento.Samples

You can reference this project using Nuget

PM> Install-Package Evento  

Evento.Repository

There is a working Repository EventStoreDomainRepository with external dependencies to EventStore.Client v20.X and Newton.Json. This library can be referenced and used in the top level host process application and injected into any Application Service that requires an IDomainRepository.

Current EventStore.Client: v21.2.1

You can reference this project using Nuget

PM> Install-Package Evento.Repository

For old eventstore 5.x version please install the package specifying the latest evento.repository v5

PM> Install-Package Evento.Repository -Version 5.1.0

Use the EventStore DomainRepository

The IDomainRepository interface expose two methods: 'Save' and GetById. The Save method take an IAggregate as parameter and a correlationId. The correlationId is used to link toghether the events that are part of the same conversation. It defines the AggregateId and when the events are stored in EventStore it is used to define the StreamId.

example creating an EventStoreDomainRepository with the word 'domain' as category

var repository = new EventStoreDomainRepository("domain", Configuration.CreateConnection("MyAdapterConnection"));

Use AggregateBase and IAggregate to build your Aggregates

namespace Domain.Aggregates
{
    public class AssociateAccount : AggregateBase
    {
        public override string AggregateId => CorrelationId;
        private string CorrelationId { get; set; }
        private Guid AssociateId { get; set; }
        private List<Income> Incomes { get; }
        private List<Expense> Expenses { get; }

        public AssociateAccount(Guid associateId, IDictionary<string, string> metadata) : this()
        {
            RaiseEvent(new AssociateAccountCreated(associateId, metadata));
        }

        public AssociateAccount()
        {
            Incomes = new List<Income>();
            Expenses = new List<Expense>();
            RegisterTransition<AssociateAccountCreated>(Apply);
            RegisterTransition<IncomeRegistered>(Apply);
            RegisterTransition<ExpenseRegistered>(Apply);
        }
        private void Apply(AssociateAccountCreated evt)
        {
            CorrelationId = evt.Metadata["$correlationId"];
            AssociateId = evt.AssociateId;
        }
        public static IAggregate Create(CreateAssociateAccount createAssociateAccount)
        {
            Ensure.NotNull(createAssociateAccount, nameof(createAssociateAccount));
            Ensure.NotEmptyGuid(createAssociateAccount.AssociateId, nameof(createAssociateAccount.AssociateId));

            return new AssociateAccount(createAssociateAccount.AssociateId, createAssociateAccount.Metadata);
        }
        
        // ....
    }