✉️ MyServiceBus

MyServiceBus (a working title) is a lightweight asynchronous messaging library inspired by MassTransit. It is designed to be minimal yet compatible with the MassTransit message envelope format and protocol, enabling services to send, publish, and consume messages across .NET and Java implementations or directly with MassTransit clients.

See samples below.

Goals

• Provide a community-driven, open-source alternative to MassTransit and MediatR as they move toward commercial licensing.
• Offer a familiar API for developers coming from MassTransit.
• Ensure wire-level and API compatibility with MassTransit so any client can communicate with MassTransit services.
• Maintain feature parity between the C# and Java clients with consistent behavior across languages. See the design guidelines for architectural and feature parity.

Features

• Fire-and-forget message sending
• Publish/subscribe pattern
• Request/response pattern (RequestClient and scoped client factory)
• RabbitMQ transport
• In-memory mediator
• Compatibility with MassTransit message envelopes
• Raw JSON messages
• Fault and error handling semantics aligned with MassTransit
• Pipeline behaviors
• OpenTelemetry support
• Annotated for use with the CheckedExceptions analyzer
• Java client and server prototypes

Specification

• MyServiceBus Specification
• ServiceBus Transport Specification
• Differences from MassTransit

Getting Started

Prerequisites

• .NET SDK
• Java (for the Java modules): JDK 17 (Gradle wrapper included)

Building

• .NET

  dotnet restore
  dotnet build

• Java build/run instructions are documented in src/Java/README.md.

Running tests

• .NET

  dotnet test

• Java

  (cd src/Java && ./gradlew test)

Quick start

Minimal steps to configure MyServiceBus and publish a message. For a broader tour of the library, see the feature walkthrough divided into basics and advanced sections.

C#

Register the bus with the ASP.NET host builder:

var builder = WebApplication.CreateBuilder(args);
builder.Services.AddServiceBus(x =>
{
    x.AddConsumer<SubmitOrderConsumer>();

    x.UsingRabbitMq((context, cfg) =>
    {
        cfg.ConfigureEndpoints(context);
    });
});

var app = builder.Build();
await app.StartAsync();
var bus = app.Services.GetRequiredService<IMessageBus>();

Define the messages and consumer:

public record SubmitOrder(Guid OrderId);
public record OrderSubmitted(Guid OrderId);

class SubmitOrderConsumer : IConsumer<SubmitOrder>
{
    public Task Consume(ConsumeContext<SubmitOrder> context) =>
        context.Publish(new OrderSubmitted(context.Message.OrderId));
}

Publish the SubmitOrder message 🚀:

await bus.Publish(new SubmitOrder(Guid.NewGuid()),
    ctx => ctx.Headers["trace-id"] = Guid.NewGuid());

Java

Register the bus:

ServiceCollection services = new ServiceCollection();

RabbitMqBusFactory.configure(services, x -> {
    x.addConsumer(SubmitOrderConsumer.class);
}, (context, cfg) -> {
    cfg.configureEndpoints(context);
});

ServiceProvider provider = services.buildServiceProvider();
ServiceBus bus = provider.getService(ServiceBus.class);
bus.start().join();

Define the messages and consumer:

record SubmitOrder(UUID orderId) { }
record OrderSubmitted(UUID orderId) { }

class SubmitOrderConsumer implements Consumer<SubmitOrder> {
    @Override
    public CompletableFuture<Void> consume(ConsumeContext<SubmitOrder> context) {
        return context.publish(new OrderSubmitted(context.getMessage().orderId()));
    }
}

Publish the SubmitOrder message:

bus.publish(new SubmitOrder(UUID.randomUUID()), ctx -> ctx.getHeaders().put("trace-id", UUID.randomUUID())).join();

Repository structure

• src/ – C# and Java source code
• test/ – Test projects
• docs/ – Documentation for using MyServiceBus, including emoji usage guidelines. Development documents live in docs/development/.
• docker-compose.yml – Docker configuration for local infrastructure

Java Quickstart

• See src/Java/README.md for detailed Java build and run instructions, including JDK 17 toolchain setup and running the testapp.

Contributing

Contributions are welcome! Please run dotnet test before submitting a pull request and follow the coding conventions described in AGENTS.md.

License

This project is licensed under the MIT License.