RabbitMQ Messaging

This tutorial takes you through setting up 2 .NET Core applications that interact through RabbitMQ.

Note

For more detailed examples, please refer to the Messaging solution in the Steeltoe Samples Repository.

First, start a RabbitMQ instance. Using the Steeltoe dockerfile, start a local instance of RabbitMQ

docker run --publish 5672:5672 steeltoeoss/rabbitmq

Next create a .NET Core WebAPI that will ensure the queue is created and write messages to it.

  1. Create a new ASP.NET Core WebAPI app with the Steeltoe Initializr Steeltoe Initialzr - RabbitMQ

  2. Name the project "WriteToRabbitMQ"

  3. Add RabbitMQ Messaging Dependency

  4. Click Generate Project to download a zip containing the new project

  5. Extract the zipped project and open in your IDE of choice

  6. Open the package manager console Visual Studio - Open Package Manager

  7. Install NuGet distributed packages

    Install-Package -Id Steeltoe.Messaging.RabbitMQ

  8. Ensure RabbitMQHost appears in Program.cs

    See RabbitMQHost documentation to further understand what is happening behind the scenes

    public static IHostBuilder CreateHostBuilder(string[] args) =>
     RabbitMQHost.CreateDefaultBuilder()
         .ConfigureWebHostDefaults(webBuilder =>
         {
             webBuilder.UseStartup<Startup>();
         });

  9. Add rabbit messaging configurations to Startup.cs

    using Steeltoe.Messaging.RabbitMQ.Config;
using Steeltoe.Messaging.RabbitMQ.Extensions;

public class Startup {
  public const string RECEIVE_AND_CONVERT_QUEUE = "steeltoe_message_queue";

  public void ConfigureServices(IServiceCollection services){

    // Add a queue to the message container that the rabbit admin will discover and declare at startup
    services.AddRabbitQueue(new Queue(RECEIVE_AND_CONVERT_QUEUE));
  }
}

  10. Create a new controller class Controllers\WriteMessageQueueController.cs

    using Microsoft.Extensions.Logging;
using Steeltoe.Messaging.RabbitMQ.Core;

[ApiController]
[Route("[controller]")]
public class WriteMessageQueueController : ControllerBase {
  public const string RECEIVE_AND_CONVERT_QUEUE = "steeltoe_message_queue";
  private readonly ILogger<WriteMessageQueueController> _logger;
  private readonly RabbitTemplate _rabbitTemplate;
  private readonly RabbitAdmin _rabbitAdmin;

  public WriteMessageQueueController(ILogger<WriteMessageQueueController> logger, RabbitTemplate rabbitTemplate, RabbitAdmin rabbitAdmin) {
  _logger = logger;
  _rabbitTemplate = rabbitTemplate;
  _rabbitAdmin = rabbitAdmin;
  }

  [HttpGet()]
  public ActionResult<string> Index() {
    var msg = "Hi there from over here.";

    _rabbitTemplate.ConvertAndSend(RECEIVE_AND_CONVERT_QUEUE, msg);

    _logger.LogInformation($"Sending message '{msg}' to queue '{RECEIVE_AND_CONVERT_QUEUE}'");

    return "Message sent to queue.";
  }
}

  11. Validate the port number the app will be served on, in Properties\launchSettings.json

    "iisSettings": {
  "windowsAuthentication": false,
  "anonymousAuthentication": true,
  "iisExpress": {
    "applicationUrl": "http://localhost:8080",
    "sslPort": 0
  }
}

Run the application (you won't be interacting directly with it, we just need it running in the background)

dotnet run<PATH_TO>\WriteToRabbitMQ.csproj
Note

Minimize windows and leave the application running as you continue on to the next step.

Now create a .NET Core WebAPI that will monitor the queue and output anything received.

  1. Create a new ASP.NET Core WebAPI app with the Steeltoe Initializr Steeltoe Initialzr - No Dependencies

  2. Name the project "MonitorRabbitMQ"

  3. No need to add any dependencies

  4. Click Generate Project to download a zip containing the new project

  5. Extract the zipped project and open in your IDE of choice

    Tip

    Open the second app in a different Visual Studio instance.

  6. Open the package manager console Visual Studio - Open Package Manager

  7. Install NuGet distributed packages

    Install-Package -Id Steeltoe.Messaging.RabbitMQ

  8. Create a new service class named RabbitListenerService.cs

    using Microsoft.Extensions.Logging;
using Steeltoe.Messaging.RabbitMQ.Attributes;

public class RabbitListenerService {
  public const string RECEIVE_AND_CONVERT_QUEUE = "steeltoe_message_queue";
  private ILogger _logger;

  public RabbitListenerService(ILogger<RabbitListenerService> logger) {
    _logger = logger;
  }

  [RabbitListener(RECEIVE_AND_CONVERT_QUEUE)]
  public void ListenForAMessage(string msg) {
    _logger.LogInformation($"Received the message '{msg}' from the queue.");
  }
}

  9. Add rabbit messaging configurations to Startup.cs

    using Steeltoe.Messaging.RabbitMQ.Extensions;

public class Startup {
  public const string RECEIVE_AND_CONVERT_QUEUE = "steeltoe_message_queue";

  public void ConfigureServices(IServiceCollection services){
    // Add steeltoe rabbit services
    services.AddRabbitServices();

    // Add singleton that will process incoming messages
    services.AddSingleton<RabbitListenerService>();

    // Tell steeltoe about singleton so it can wire up queues with methods to process queues
    services.AddRabbitListeners<RabbitListenerService>();
  }
}

  10. Validate the port number the app will be served on, in Properties\launchSettings.json

    "iisSettings": {
  "windowsAuthentication": false,
  "anonymousAuthentication": true,
  "iisExpress": {
    "applicationUrl": "http://localhost:8081",
    "sslPort": 0
  }
}

Run the application

dotnet run<PATH_TO>\WriteToRabbitMQ.csproj
Note

If a browser window popped up, minimize it.

Validate the apps are working properly and the message queue is in use.

  1. View the WriteToRabbitMQ project message logs and verify there is a message stating it is "Sending message to queue". If you don't see the message refresh the endpoint https://localhost:8080/WriteMessageQueue to have a new message written. Visual Studio - Debug Output
  2. View the MonitorRabbitMQ project message logs and verify there is a message stating it "Received the message from the queue". Visual Studio - Debug Output Message Received