Integrating the RabbitMQ client in a .NET Core application

I couldn’t find a good example on the best way to integrate the RabbitMQ C# client in a .NET core application. So time to write a post about it.

I would recommend to use the Hosted Services, either directly through the IHostedService or through the BackgroundService.

Let’s see how to do it using the BackgroundService:

• We create a new class that inherits from BackgroundService:

	public class RabbitMQHostedService: BackgroundService {
	private ConnectionFactory _connectionFactory;
	private IConnection _connection;
	private IModel _channel;
	public RabbitMQHostedService()
	{
	}
	}

view raw RabbitMQHostedService.cs hosted with ❤ by GitHub

• We’ll use the StartAsync method to create the Connectionfactory, Connection and a Channel to listen on:

	public override Task StartAsync(CancellationToken cancellationToken)
	{
	_connectionFactory = new ConnectionFactory
	{
	UserName = "<user>",
	Password = "<pw>",
	DispatchConsumersAsync = true
	};
	_connection = _connectionFactory.CreateConnection();
	_channel = _connection.CreateModel();
	_channel.QueueDeclare(queue: "<queuename>",
	durable: true,
	exclusive: false,
	autoDelete: false,
	arguments: null);
	return base.StartAsync(cancellationToken);
	}

view raw StartAsync.cs hosted with ❤ by GitHub

Remark: Notice the DispatchConsumersAsync = true in the ConnectionFactory configuration. This is important to be able to use an async consumer. If you don’t add this configuration no messages will be picked up by the AsyncEventingBasicConsumer.

• We also implement the StopAsync method to cleanup when our backgroundservice is shutdown:

	public override async Task StopAsync(CancellationToken cancellationToken)
	{
	await base.StopAsync(cancellationToken);
	_connection.Close();
	}

view raw StopAsync.cs hosted with ❤ by GitHub

• Now the only thing left is to create a consumer to start receiving messages. We’ll use the ExecuteAsync method for that:

	protected override async Task ExecuteAsync(CancellationToken stoppingToken)
	{
	stoppingToken.ThrowIfCancellationRequested();
	var consumer = new AsyncEventingBasicConsumer(_channel);
	consumer.Received += async (bc, ea) =>
	{
	var message = Encoding.UTF8.GetString(ea.Body.ToArray());
	try
	{
	//Add message parsing and handling logic here
	_channel.BasicAck(ea.DeliveryTag, false);
	}
	catch(Exception ex)
	{
	_channel.BasicNack(ea.DeliveryTag, false, false);
	}
	};
	_channel.BasicConsume(queue: "<queuename>", autoAck: false, consumer: consumer);
	await Task.CompletedTask;
	}

view raw ExecuteAsync.cs hosted with ❤ by GitHub

• Of course we should not forget to register our Hosted Service:

services.AddHostedService<RabbitMQHostedService>();

view raw AddHostedService.cs hosted with ❤ by GitHub