✉️ MyServiceBus

MyServiceBus (working title) is a transport-agnostic, asynchronous messaging framework for Java and .NET, inspired by MassTransit.

It provides a consistent, opinionated application-level messaging model—independent of brokers and application frameworks—while remaining compatible with the MassTransit message envelope format and semantics. This makes it possible for Java and .NET services to send, publish, and consume messages across platforms, or interoperate directly with existing MassTransit-based systems.

See samples below.

---

What is MyServiceBus?

MyServiceBus defines a stable messaging runtime with concepts such as:

• publish vs send
• consumers
• request/response
• retries and error handling
• middleware / pipeline behaviors
• scheduling
• in-memory testing

These semantics remain consistent regardless of the underlying transport or host framework.

Unlike most Java messaging solutions, MyServiceBus does not require a framework-wide commitment (such as Spring). It can be used as a self-contained runtime, integrated into an existing application, or composed via factories and decorators—depending on project needs.

---

Goals

• Provide a community-driven, open-source alternative to MassTransit and MediatR as they move toward commercial licensing.
• Preserve a MassTransit-compatible messaging model across Java and .NET.
• Enable Java services to easily connect with .NET/C# services using shared messaging semantics.
• Offer a familiar experience for developers coming from .NET.
• Maintain feature parity and consistent behavior between the C# and Java implementations.
  See the design guidelines for architectural and behavioral parity.

---

Features

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

---

Specification

• MyServiceBus Specification
• ServiceBus Transport Specification
• Differences from MassTransit

---

Getting Started

Prerequisites

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

Building

• .NET

  dotnet restore
  dotnet build

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

Running tests

• .NET

  dotnet test

• 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, which covers both basic and advanced usage.

---

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 = ServiceCollection.create();

services.from(MessageBusServices.class)
        .addServiceBus(cfg -> {
            cfg.addConsumer(SubmitOrderConsumer.class);
            cfg.using(
                RabbitMqFactoryConfigurator.class,
                (context, rbCfg) -> rbCfg.configureEndpoints(context)
            );
        });

ServiceProvider provider = services.buildServiceProvider();
MessageBus bus = provider.getService(MessageBus.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, including the feature walkthrough and specifications 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 test application.

---

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.