Dorn.Messaging 1.0.0

Dorn.Messaging

MIT-licensed in-process mediator. No commercial licensing, no surprises.

Implementation of Dorn.Messaging.Contracts — dispatches commands and queries to their handlers, and notifications to all registered handlers.

Registration

// One line to rule them all
builder.Services.AddMediator(typeof(CreateTodoItemCommand).Assembly);

AddMediator registers:

• ISender and IPublisher as scoped services
• All IRequestHandler<,> implementations
• All INotificationHandler<> implementations
• All IPipelineBehavior<,> implementations

Auto-discovers everything in the provided assembly via reflection.

Send a command or query

public sealed record CreateTodoItemCommand(string Title) : IRequest<Guid>;

// In your endpoint
var id = await sender.Send(new CreateTodoItemCommand("My task"), ct);

Publish domain events

// In your aggregate
public class TodoItem : AggregateRoot
{
    public static TodoItem Create(string title)
    {
        var item = new TodoItem { Title = title };
        item.AddDomainEvent(new TodoItemCreatedEvent(item.Id));
        return item;
    }
}

// In your DbContext — dispatches after SaveChanges
public override async Task<int> SaveChangesAsync(CancellationToken ct)
{
    var events = ChangeTracker
        .Entries<AggregateRoot>()
        .Select(e => e.Entity)
        .Where(e => e.DomainEvents.Count > 0)
        .ToList();

    var result = await base.SaveChangesAsync(ct);

    foreach (var entity in events)
    {
        foreach (var domainEvent in entity.DomainEvents.ToArray())
        {
            await _publisher.Publish(domainEvent, ct);
            entity.ClearDomainEvents();
        }
    }

    return result;
}

Pipeline behaviors

Behaviors execute in reverse registration order — the last registered behavior is the outermost wrapper.

// Registered first → runs first (innermost)
services.AddMediator(typeof(CreateTodoItemCommand).Assembly);
services.AddTransient(typeof(IPipelineBehavior<,>), typeof(LoggingBehavior<,>));
services.AddTransient(typeof(IPipelineBehavior<,>), typeof(ValidationBehavior<,>));

Installation

dotnet add package Dorn.Messaging

Depends on Dorn.Messaging.Contracts and Microsoft.Extensions.DependencyInjection.Abstractions.