EventWeave

Lightweight event aggregation for .NET. Zero dependencies. Decoupled pub/sub messaging between services.

Why

When services need to communicate without knowing about each other, you need a message bus. EventWeave provides a minimal IEventAggregator that handles subscription, publication, and cleanup — with weak references to prevent memory leaks.

No frameworks. No reflection. No magic. Just pub/sub.

Install

dotnet add package EventWeave
dotnet add package EventWeave.CommunityToolkit

Install into Unity

In Package Manager add the following git url:

https://github.com/olivegamestudio/EventWeave.git?path=/upm

Quick start

Define a message as a record:

public sealed record OrderPlacedMessage(int OrderId, decimal Total);

Subscribe:

public sealed class NotificationService
{
    public NotificationService(IEventAggregator events)
    {
        events.Subscribe<OrderPlacedMessage>(this, OnOrderPlaced);
    }

    void OnOrderPlaced(OrderPlacedMessage message)
    {
        // send notification
    }
}

Publish:

public sealed class OrderService
{
    readonly IEventAggregator _events;

    public OrderService(IEventAggregator events)
    {
        _events = events;
    }

    public void PlaceOrder(int orderId, decimal total)
    {
        // process order
        _events.Publish(new OrderPlacedMessage(orderId, total));
    }
}

Unsubscribe when done:

events.Unsubscribe(this);

Setup

Standalone (no DI)

IEventAggregator events = new EventAggregator();

Microsoft DI

services.AddSingleton<IEventAggregator, EventAggregator>();

CommunityToolkit.Mvvm adapter

If you already use IMessenger in your presentation layer and want EventWeave in your application layer:

dotnet add package EventWeave.CommunityToolkit

services.AddSingleton<IMessenger, WeakReferenceMessenger>();
services.AddSingleton<IEventAggregator, MessengerEventAggregator>();

Diagnostics

Publish automatically captures caller information for debugging:

public interface IEventAggregator
{
    void Publish<TMessage>(
        TMessage message,
        [CallerMemberName] string? caller = null,
        [CallerFilePath] string? file = null)
        where TMessage : class;
}

Packages

Package	Purpose
EventWeave	Core library. IEventAggregator, EventAggregator. Zero dependencies, netstandard2.0.
EventWeave.CommunityToolkit	Adapter MessengerEventAggregator wrapping IMessenger from CommunityToolkit.Mvvm.

Design principles

• Zero dependencies in the core package. Runs on .NET Framework 4.6.2, .NET 10, Unity, MonoGame — anywhere netstandard2.0 works.
• Thread safe. Subscriptions and publications are safe to call from any thread.
• No reflection. All wiring is explicit or source-generated.
• Messages are records. Immutable, equatable, pattern-matchable.

License

MIT