EventBus implementation 🚌

Event Bus - design pattern for abstract communication between software components.

This design pattern works on the concept of subscriber-publisher interaction, similar to the message brokers. 📫

System does not provide protection from duplicate events invocation.

Base concepts of implementation:

IEventListener - listener/handler of the event. (subscriber) 👂

IEvent - event object that can be handled by listeners. ⬛

IEventBus - bus where any publisher can raise new event, can be used as a listener to replicate passed events. ⚙️

Usage:

1. Declaration of the event. (IEvent is a marker interface which allows us to treat object as an event)

public class SomeEvent : IEvent
{
    public int SomeParameter;
}

2. Bus instantiation.

IEventBus bus = new EventBus();

3. Listener instantiation and usage.

// consider that this code is from the other system component
void LogHandler(SomeEvent @event) =>
    Console.WriteLine("SomeParameter: {0}", @event.SomeParameter);

var handler = LogHandler; // delegate
var listener = handler.ToListener(); // = new EventListener<SomeEvent>(handler);

var listenerEntry = listener.Listen(bus);

4. Raising events.

SomeEvent @event = new () { SomeParameter = 42 };

await @event.Raise(bus);

5. Listener dispose.

listenerEntry.Dispose(); // listener entry will not handle any more events from the bus it listens to