Rebus - how to register an instance of a handler

Question

I'm trying to use Rebus in C# as an alternative to Java's org.greenrobot.eventbus.EventBus. Can't figure out how to register an isntance of a handler dynamically.

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Goal:

• Start the bus
• Register handler isntances dynamically at runtime (e.g. add new one when user presses a button)
• Receive some messages by those handlers
• Stop the bus

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Current code:(NUnit) It only prints some diagnostic output from Rebus itself, but not the messages.

using System;
using System.Threading.Tasks;
using Rebus.Config;
using Rebus.Transport.InMem;
using NUnit.Framework;
using Rebus.Activation;
using Rebus.Handlers;

[TestFixture]
public class RebusTests
{
    BuiltinHandlerActivator activator = new BuiltinHandlerActivator();
    InMemNetwork network = new InMemNetwork(true);
    private string inputQueueName = "inputQueue";

    [SetUp]
    public void Setup() {
        Configure.With(activator)
            .Transport(t => t.UseInMemoryTransport(network, inputQueueName))
            .Start();
    }

    [TearDown]
    public void Cleanup() {
        activator.Dispose();
    }

    [Test]
    public void TestHandlingStrings() {
        var h1 = new StringHandler("handler 1");
        var h2 = new StringHandler("handler 2");

        int workersCount = activator.Bus.Advanced.Workers.Count;
        activator.Bus.Advanced.Workers.SetNumberOfWorkers(0);
        activator.Register(() => h1);
        activator.Register(() => h2);
        activator.Bus.Advanced.Workers.SetNumberOfWorkers(workersCount);

        activator.Bus.Advanced.SyncBus.SendLocal("Good day, sir.");
    }
}

public class StringHandler : IHandleMessages<string> {
    public readonly string handlerName;

    public StringHandler(string handlerName) {
        this.handlerName = handlerName;
    }

    public Task Handle(string message) {
        Console.WriteLine($"1) Handler [{handlerName}] got: {message}");
        return Task.Run(() => { Console.WriteLine($"2) Handler [{handlerName}] got: {message}"); });
    }
}

Answer 1

The code

[Test]
public void TestHandlingStrings() {
    var h1 = new StringHandler("handler 1");
    var h2 = new StringHandler("handler 2");

    int workersCount = activator.Bus.Advanced.Workers.Count;
    activator.Bus.Advanced.Workers.SetNumberOfWorkers(0);
    activator.Register(() => h1);
    activator.Register(() => h2);
    activator.Bus.Advanced.Workers.SetNumberOfWorkers(workersCount);

    activator.Bus.Advanced.SyncBus.SendLocal("Good day, sir.");
}

will exit almost immediately, so the bus is likely to never get to receive anything.

If you insert a little Thread.Sleep(TimeSpan.FromSeconds(2)); at the end of the test, I bet your message will be received:

[Test]
public void TestHandlingStrings() {
    var h1 = new StringHandler("handler 1");
    var h2 = new StringHandler("handler 2");

    int workersCount = activator.Bus.Advanced.Workers.Count;
    activator.Bus.Advanced.Workers.SetNumberOfWorkers(0);
    activator.Register(() => h1);
    activator.Register(() => h2);
    activator.Bus.Advanced.Workers.SetNumberOfWorkers(workersCount);

    activator.Bus.Advanced.SyncBus.SendLocal("Good day, sir.");

    Thread.Sleep(TimeSpan.FromSeconds(2));
}