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

2. Name the project "WriteToRabbitMQ"

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

6. Open the package manager console

7. Install NuGet distributed packages

   Install-Package -Id Steeltoe.Messaging.RabbitMQ
   

8. 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 steeltoe rabbit services
       services.AddRabbitServices();
   
       // Add the steeltoe rabbit admin client... will be used to declare queues below
       services.AddRabbitAdmin();
   
       // 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));
   
       // Add the rabbit client template used for send and receiving messages
       services.AddRabbitTemplate();
     }
   }
   

9. 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.";
     }
   }
   

10. 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)

• .NET cli
• Visual Studio

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

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

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

• .NET cli
• Visual Studio

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.
2. View the MonitorRabbitMQ project message logs and verify there is a message stating it "Received the message from the queue".