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Gaurav
Gaurav

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🚀 Getting Started with RabbitMQ Pub/Sub using MassTransit in .NET

In this guide, we’ll set up a Publisher/Consumer architecture using RabbitMQ and MassTransit in .NET. We’ll cover:

  • Docker setup for RabbitMQ
  • Publisher configuration in ASP.NET Core
  • Consumer setup in a .NET Console App
  • Sending and receiving messages

🐳 Step 1: Run RabbitMQ in Docker
Create a file named docker-compose.yml with the following content:

version: '3' services: rabbitmq: image: rabbitmq:3-management container_name: rabbitmq ports: - "5672:5672" - "15672:15672" environment: RABBITMQ_DEFAULT_USER: guest RABBITMQ_DEFAULT_PASS: guest
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Then run:

docker-compose up -d
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✅ RabbitMQ Management UI: http://localhost:15672
Username: guest
Password: guest

📆 Step 2: Create the Shared Event Model

This model will be shared between publisher and consumer:

namespace Response.EventModel; public class EventModel { public string message { get; set; } }
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📨 Step 3: Setup the Publisher in ASP.NET Core

🔹 Add NuGet Packages

<PackageReference Include="MassTransit" Version="8.4.1" /> <PackageReference Include="MassTransit.RabbitMQ" Version="8.4.1" />
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🔹 Create the Publisher Class

using MassTransit; using Response.EventModel; namespace TechnicianAdmin.Event; public class Publisher { private readonly IPublishEndpoint _publishEndpoint; public Publisher(IPublishEndpoint publishEndpoint) { _publishEndpoint = publishEndpoint; } public async Task PublishMessage() { var message = new EventModel { message = "Hey this is testing message from publisher" }; await _publishEndpoint.Publish(message); } }
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🔹 Register MassTransit in Dependency Injection

using MassTransit; using TechnicianAdmin.Event; public static class AddMassTransitConfiguration { public static IServiceCollection MassTransitConfiguration(this IServiceCollection services) { services.AddTransient<Publisher>(); services.AddMassTransit(x => { x.SetKebabCaseEndpointNameFormatter(); // Auto-discover consumers in the assembly (optional) x.AddConsumers(typeof(Program).Assembly); x.UsingRabbitMq((context, cfg) => { cfg.Host("localhost", "/", h => { h.Username("guest"); h.Password("guest"); }); cfg.ConfigureEndpoints(context); }); }); return services; } }
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🔹 Inject and Use Publisher in Controller

private readonly Publisher _publishEndpoint; public Controller(Publisher publishEndpoint) { _publishEndpoint = publishEndpoint; } [AllowAnonymous] [HttpGet("publish-rabbitMQ-message")] public async Task<IActionResult> SendMessage() { await _publishEndpoint.PublishMessage(); return Ok("Message sent to RabbitMQ"); }
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🗒️ Step 4: Setup the Consumer in a .NET Console App

🔹 Add NuGet Packages

<PackageReference Include="MassTransit.RabbitMQ" Version="8.4.1" /> <PackageReference Include="Microsoft.Extensions.Hosting" Version="9.0.5" /> <PackageReference Include="Microsoft.Extensions.Hosting.Abstractions" Version="9.0.5" /> <PackageReference Include="RabbitMQ.Client" Version="7.1.2" />
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🔹 Create the EventModel Again (or Share It via Class Library)

namespace Response.EventModel; public class EventModel { public string message { get; set; } }
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🔹 Create the Consumer

using MassTransit; using Response.EventModel; namespace ConsoleApp1; public class HelloMessageConsumer : IConsumer<EventModel> { public Task Consume(ConsumeContext<EventModel> context) { Console.WriteLine($"Received message: {context.Message.message}"); return Task.CompletedTask; } }
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🔹 Setup MassTransit in Program.cs

using ConsoleApp1; using MassTransit; using Microsoft.Extensions.DependencyInjection; using Microsoft.Extensions.Hosting; var builder = Host.CreateDefaultBuilder(args); builder.ConfigureServices((hostContext, services) => { services.AddMassTransit(x => { x.AddConsumer<HelloMessageConsumer>(); x.UsingRabbitMq((context, cfg) => { cfg.Host("localhost", "/", h => { h.Username("guest"); h.Password("guest"); }); cfg.ReceiveEndpoint("hello-message-queue", e => { e.ConfigureConsumer<HelloMessageConsumer>(context); }); }); }); }); await builder.Build().RunAsync();
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✅ Test the Flow

  1. Make sure RabbitMQ is running via Docker.
  2. Run the consumer app.
  3. Hit the API endpoint:GET http://localhost:/publish-rabbitMQ-message
  4. You should see output like:

Received message: Hey this is testing message from publisher

🧠 Conclusion

Congrats! 🎉 You’ve successfully:

  • Set up RabbitMQ using Docker
  • Published a message via ASP.NET Core
  • Consumed it via a .NET Console App This pattern forms the foundation of microservices-based communication using MassTransit + RabbitMQ in the .NET ecosystem.

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