Flux.Messaging

Flux.Messaging is a messaging framework for .NET designed for Clean Architecture, DDD, and distributed systems.
It provides a unified model for:

• Publish / Subscribe (fire-and-forget)
• Distributed Request / Response
• Strongly-typed handlers
• Pluggable transports (InMemory, AMQP, etc.)

Flux.Messaging does not try to hide messaging complexity — it structures it properly.

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Key Features

• Clear separation between Bus, Dispatcher, and Transport
• First-class support for distributed request-response
• Contract-first design
• DDD / CQRS / Event-Driven friendly
• No dependency on ASP.NET
• Ready for AMQP 1.0 (Qpid, Azure Service Bus, etc.)
• InMemory transport for testing and local development

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Packages

Package	Description
Flux.Messaging.Abstractions	Public contracts (Bus, Handlers, Envelope, Transport)
Flux.Messaging.Core	Core implementations
Flux.Messaging.InMemory	InMemory transport and dispatcher
Flux.Messaging.Extensions.DependencyInjection	Developer Experience (DX)

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Core Concepts

Publish (Event)

• Fire-and-forget
• Multiple handlers supported
• No response expected

Send (Request)

• Request / Response
• Exactly one handler
• Uses CorrelationId and ReplyTo
• Can cross process and service boundaries

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Installation

dotnet add package Flux.Messaging

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Basic Setup (InMemory)

services.AddFluxMessaging()
        .UseInMemory();

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Publish (Event)

Event definition

public record ProductAdded(Guid ProductId);

Handler

public sealed class ProductAddedHandler : IMessageHandler<ProductAdded>
{
    public Task HandleAsync(ProductAdded message, CancellationToken ct = default)
    {
        Console.WriteLine($"Product added: {message.ProductId}");
        return Task.CompletedTask;
    }
}

Publish

await messageBus.PublishAsync(new ProductAdded(productId));

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📥 Send (Request / Response)

Request

public sealed record ReserveStock(Guid ProductId, int Quantity)
    : IRequest<ReserveStockResult>;

Response

public sealed record ReserveStockResult(bool Success);

Handler

public sealed class ReserveStockHandler
    : IRequestHandler<ReserveStock, ReserveStockResult>
{
    public Task<ReserveStockResult> HandleAsync(
        ReserveStock request,
        CancellationToken ct = default)
    {
        return Task.FromResult(new ReserveStockResult(true));
    }
}

Send

var result = await messageBus.SendAsync<ReserveStockResult>(
    new ReserveStock(productId, 2));

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Architecture Overview

Application
 └─ IMessageBus
      ├─ Send (Request)
      └─ Publish (Event)

Infrastructure
 ├─ ITransport (AMQP, InMemory, etc.)
 └─ IMessageDispatcher

• Bus: public API
• Dispatcher: resolves handlers
• Transport: delivers envelopes

The transport does not know handlers.
The dispatcher does not know the transport.

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Cross-language interoperability

Flux.Messaging is .NET-first, but transport-agnostic.

Other languages can:

• Consume AMQP envelopes
• Deserialize the payload
• Reply using ReplyTo and CorrelationId

No framework dependency is required.

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Testing

The solution includes behavior-focused tests:

• Concurrency
• Multiple handlers
• Fault tolerance
• Dispatch correctness

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License

This project is licensed under the Apache License, Version 2.0.
See the LICENSE file for details.