Using RabbitMQ in ASP.NET Core MVC

Question

I am writing an ASP.NET Core MVC app with RabbitMQ. I am able to implement pub/sub patterns successfully. However, I am facing an issue to show subscribe message on the App.

Connection method on HomeController:

    [HttpPost]
    public IActionResult Index(string serverName, string userName, string password, string port)
    {
        RabbitMq rabbitMq = new RabbitMq();
        var pubConnection = rabbitMq.CreateConnection(serverName, userName, password, port);

        if (!pubConnection.IsOpen)
        {
            ViewBag.NotConnected = "Not Connected. Try Again.";
            return View();
        }

        var subConnection = rabbitMq.CreateConnection(serverName, userName, password, port);

        MyClient myClient = new MyClient();
        myClient.CreatePublisher(pubConnection);
        myClient.CreateSubscriber(subConnection);

        return RedirectToAction(actionName: "Index", controllerName: "MyClientXYZ", routeValues: null);
    }

Subscriber method on MyClient class :

public void CreateSubscriber(IConnection pubSubConnection)
{
        var channel = pubSubConnection.CreateModel();

        channel.ExchangeDeclare("MyExchange", ExchangeType.Fanout, durable: true, true);
        channel.ExchangeBind("MyExchange", "ClientExchange", "#", null);
        var slotQueueName = channel.QueueDeclare("my queue", true, autoDelete: true).QueueName;
        channel.QueueBind(slotQueueName, "MyExchange", routingKey: "");

        var consumer = new EventingBasicConsumer(channel);

        consumer.Received += (model, ea) =>
        {
            var body = ea.Body.ToArray();
            var message = Encoding.UTF8.GetString(body);
            Console.WriteLine(" [x] {0}", message);
        };

        channel.BasicConsume(queue: slotQueueName,
            autoAck: true,
            consumer: consumer);
}

I am able to print subscriber messages on the console. But I need to show this message on the UI (View, any JS popup, etc.) I tried many ways like set subscribe message into TempData["subMessage"], redirectToAction(), open JS popup to show subscriber message. But, I couldn't do.

I just want to show the subscriber message on the UI when the callback method executes.

I don't quite understand your thought process. You create an RMQ connection in a controller action, return a result, the connection is disposed of.. what provides that enduring connection to the client to push updates? Or is this a polling solution? It feels like you should have your rmq as a constantly running thing somewhere else (not initiated by controller action) that pushes messages, upon their publish, into a SignalR hub to which your javascript client is connected, and that will cause an event at the client side that you can use to update the ui. — Caius Jard
– Caius Jard, Commented Apr 18, 2021 at 5:42
Also is there a necessary reason to create multiple connections? Like @Caius says, you usually create one connection for the lifetime of your app and use it to create whatever subscriber/publisher channels you need — Rex Henderson
– Rex Henderson, Commented Apr 18, 2021 at 6:10
It might even be possible to have a javascript client subscribe to an RMQ directly (I've never looked/tried) in which case that could hand a boatload off work off to the client<->RMQ and leave the server out of it; anything you want on the client just push it into the queue — Caius Jard
– Caius Jard, Commented Apr 18, 2021 at 6:15
yea, I need to have two connections. Actually, I am creating a test app for testing another app. — KiddoDeveloper
– KiddoDeveloper, Commented Apr 18, 2021 at 6:24
We are using signalR for that matter. When event compeltes it calls an signalR event on the client side and updates the data. Might help. — MonkeyDLuffy
– MonkeyDLuffy, Commented Apr 18, 2021 at 9:54

Jevon Kendon · Accepted Answer · 2021-04-18 22:41:28Z

2

This is not right. RabbitMQ connections, and consumers, are long lived entities; not something ephemeral that you initiate in a controller action.

The short answer is to use a framework on top of RabbitMQ. Here's two good ones to consider:

The long answer is to roll your own RabbitMQ infrastructure. You do this if you are an expert and have some special need. In that case, maybe start here:

https://www.rabbitmq.com/tutorials/tutorial-one-dotnet.html

The other answer is to completely re-evaluate what you are trying to achieve.

Good luck.

edited Apr 18, 2021 at 22:41

answered Apr 18, 2021 at 22:35

Jevon Kendon

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