.NET Core Microservice using RabbitMQ

Question

I am planing to use Microservice architecture for a project. The selected technology stack is .NET Core with Docker and RabbitMQ as a simple service bus and this should be able to deploy on Linux.

Lets say I have a Payment service and an Order Service, I want each of these services to expose REST endpoints. Because of that, I thought of making these two services as .NET Core Web APIs.

But the problem is the inter-service communication using RabbitMQ. Whenever I get a new order, I want to publish an event using RabbitMQ and then listen to that event in Payment service to perform certain operations (database updates). But since these are Web APIs, I don't think it's possible to listen to events as I described. (I feel like I might have to use something like a console application to subscribe to events.)

I would like to find the most viable method to achieve this using the best practices considering the scalability and extendability of the system.

ASP.NET Core applications are console application. You can simply create an object that will listen to messages at application startup along with WebAPI registration.. — Andrii Litvinov, Apr 19 '17 at 08:19
@AndriiLitvinov, Thank you for the response. Could you please explain a bit your suggestion? — PIKP, Apr 19 '17 at 08:31

Andrii Litvinov · Answer 1 · 2017-09-03T08:50:22.880

11

When you create your application with .NET Core you bootstrap things in Main method and then register services and middle-ware in Startup class. So before you start web host you can also create and start your messaging services:

public class MessageListener
{
    public void Start()
    {
        // Listen to rabbit QM and all the things.
    }
}

public static void Main(string[] args)
{
    // Listen to messages.
    var messaging =  MessageListener();
    messaging.Start();

    // Configure web host and start it.
    var host = new WebHostBuilder()
        ...
        .Build();
    host.Run();
}

UPDATE:

In ASP.NET Core 2.0 IHostedService interface was introduced to achieve same goal and they mention this scenario in their announcement. Here is an example of how to implement one.

edited Sep 03 '17 at 08:50

answered Apr 19 '17 at 08:42

Andrii Litvinov

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So what you are saying is, even in a .NET Core Web API project, I can simply register my listeners to handle event that will be published by other services? – PIKP Apr 19 '17 at 08:49
Yup, exactly that. If the logic of the subdomain is implemented in a service it does not matter how commands are send: through web api or through message queue. – Andrii Litvinov Apr 19 '17 at 08:50
Thanks, do you think it's a good idea to handle it like this? will there be any drawbacks? – PIKP Apr 19 '17 at 09:11
2

That's how I do it in my projects. The idea of microservice is to implemented a Bounded Context (a subdomain or part of it). It should have a domain model inside, which can be accessed either from web api controllers or from message handlers. – Andrii Litvinov Apr 19 '17 at 09:15
@PIKP, please check the updated if that's still relevant for you. – Andrii Litvinov Sep 03 '17 at 08:50

.NET Core Microservice using RabbitMQ

1 Answers1