TinyBlueWhale.MiniBus

Minimal high-performance in-process mediator for .NET.

Focused only on what most applications actually use every day:

• Send()
• Publish()

No pipelines. No behaviors. No decorators. No framework ceremony.

Built for:

• Minimal APIs
• CQRS-lite architectures
• Vertical Slice Architecture
• Fast startup
• Low allocations
• Simple codebases

---

Why?

Most projects use MediatR for:

await mediator.Send(command);
await mediator.Publish(@event);

That is the real-world 80%.

TinyBlueWhale.MiniBus exists to solve exactly that with:

• fewer allocations
• faster startup
• simpler internals
• zero unnecessary abstractions
• extremely small codebase

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Features

• Minimal API surface
• Assembly scanning
• Request/Response support
• Multi-handler event publishing
• Native Dependency Injection support
• CancellationToken propagation
• Fast startup time
• Low memory allocations
• Zero external mediator dependencies

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Installation

Install-Package TinyBlueWhale.MiniBus

or

dotnet add package TinyBlueWhale.MiniBus

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Quick Start

1. Register MiniBus

using TinyBlueWhale.MiniBus;

builder.Services.AddMiniBus(typeof(CreateOrderHandler).Assembly);

---

2. Create a Request

public sealed record CreateOrderCommand(
    string CustomerEmail,
    decimal TotalAmount)
    : IRequest<Guid>;

---

3. Create a Handler

public sealed class CreateOrderHandler
    : IRequestHandler<CreateOrderCommand, Guid>
{
    public Task<Guid> Handle(
        CreateOrderCommand request,
        CancellationToken cancellationToken = default)
    {
        return Task.FromResult(Guid.NewGuid());
    }
}

---

4. Send Request

var orderId = await miniBus.Send(
    new CreateOrderCommand(
        "customer@company.com",
        1499.99m));

---

Events

Create Event

public sealed record OrderCreatedEvent(
    Guid OrderId,
    string CustomerEmail);

---

Create Event Handler

public sealed class SendConfirmationEmailHandler
    : IEventHandler<OrderCreatedEvent>
{
    public Task Handle(
        OrderCreatedEvent @event,
        CancellationToken cancellationToken = default)
    {
        Console.WriteLine(
            $"Confirmation email sent to '{@event.CustomerEmail}'.");

        return Task.CompletedTask;
    }
}

---

Publish Event

await miniBus.Publish(
    new OrderCreatedEvent(orderId, customerEmail));

---

Benchmarks

Environment:

• .NET 9
• Intel i7-1185G7
• BenchmarkDotNet

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Startup Registration

Method	Mean	Allocated
TinyBlueWhale.MiniBus	7.067 ms	2.63 MB
MediatR	565.032 ms	23.56 MB

TinyBlueWhale.MiniBus startup registration is ~80x faster.

---

Send()

Method	Mean	Allocated
TinyBlueWhale.MiniBus	54.40 ns	168 B
MediatR	87.32 ns	336 B

TinyBlueWhale.MiniBus executes requests ~1.6x faster with half the allocations.

---

Publish() with 50 Handlers

Method	Mean	Allocated
TinyBlueWhale.MiniBus	1.565 μs	1.17 KB
MediatR	1.544 μs	7.55 KB

TinyBlueWhale.MiniBus keeps similar publish throughput with significantly lower memory allocations.

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Example Project

Repository includes a complete Minimal API example:

TinyBlueWhale.MiniBus.Example.ECommerce

Includes:

• Commands
• Queries
• Events
• Multiple event handlers
• Swagger
• Vertical Slice Architecture

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Philosophy

TinyBlueWhale.MiniBus intentionally avoids:

• pipelines
• behaviors
• middleware chains
• decorators
• feature creep
• enterprise ceremony

If your application needs advanced orchestration frameworks, MediatR is still an excellent choice.

TinyBlueWhale.MiniBus is designed for applications that want:

• simplicity
• speed
• maintainability
• tiny abstractions

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Roadmap

Potential future improvements:

• source generators
• compile-time registration
• analyzers
• AOT optimizations

Without sacrificing simplicity.

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Contributing

Contributions are welcome.

Rules:

• Keep the core minimal.
• Avoid unnecessary abstractions.
• Performance regressions are not accepted.
• Every feature must justify its complexity.