dotnet-event-kit

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A lightweight, high-performance in-process event bus for .NET applications. Publish strongly-typed events, subscribe async handlers, and decouple components without external message brokers.

Features

• Strongly-typed events — publish and subscribe with full type safety, no casting or string keys
• Async-native handlers — all handlers are ValueTask-based with CancellationToken support
• Ordered dispatch — handlers execute in registration order with configurable parallelism
• Handler priorities — control execution order across independently registered handlers
• Scoped & singleton handlers — register handlers with DI lifetime management
• Error isolation — one handler failure doesn't kill other subscribers; configurable error policies
• Event filtering — subscribe to events matching a predicate without processing every publish
• Dead letter support — capture events with no registered handlers for debugging
• Middleware pipeline — wrap event dispatch with cross-cutting concerns (logging, timing, retry)
• Zero external dependencies — built entirely on .NET 8 primitives

Installation

dotnet add package JG.EventKit

Quick Start

// Register in DI
builder.Services.AddEventKit(options =>
{
    options.OnError = EventErrorPolicy.LogAndContinue;
});

// Define an event
public record UserRegistered(string UserId, string Email, DateTime Timestamp);

// Subscribe a handler
builder.Services.AddEventHandler<UserRegistered, WelcomeEmailHandler>();

public class WelcomeEmailHandler : IEventHandler<UserRegistered>
{
    public async ValueTask HandleAsync(UserRegistered e, CancellationToken ct)
    {
        await SendWelcomeEmail(e.Email, ct);
    }
}

// Publish from anywhere
public class RegistrationService(IEventBus bus)
{
    public async Task RegisterAsync(string email)
    {
        var user = CreateUser(email);
        await bus.PublishAsync(new UserRegistered(user.Id, email, DateTime.UtcNow));
    }
}

Documentation

• Getting Started — Setup, handlers, middleware, and full examples
• API Reference — Complete API surface with type tables and code samples

Contributing

Contributions are welcome! Please feel free to submit a Pull Request.

License

Licensed under the Apache License 2.0. See LICENSE for details.

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Ready to get started? Install via NuGet and check out the API reference.