Event Manager

Description:

A Basic EventManager singleton and EventBus class to subscribe Listener and emit events

version:

1.0

1. EventManager singleton class
2. EventManager Emit and subscribe methods
3. EventBus class with subscribe and private getIdGenerator method

1.1.0

1. Fix EventBus subscribes handler execution (fire-and-forget)
2. Add a new EventBusInterface to allow switch between an EventBus in memory or a KafkaImplementation

EventBus Interface and Kafka adapter

• EventBusInterface: A runtime abstract class in src/EventBusInterface.js that documents the expected API for EventBus implementations. Methods: subscribe(eventType, eventHandler), publish(event), optional connect() and disconnect() for async implementations.

• In-memory EventBus: src/EventBus.js implements the interface and remains the default used by the EventManager singleton.

3. KafkaEventBus implementation:

   1. KafkaEventBus is an adapter that uses kafkajs (optional dependency). To use it:

   2. Steps:

      1. Install kafkajs:

      npm install kafkajs

   3. Create and inject the Kafka bus:

   const KafkaEventBus = require('./src/KafkaEventBus');
   const EventManagerClass = require('./src/EventManager');
   
   const kafkaBus = new KafkaEventBus({ brokers: ['localhost:9092'] });
   const manager = new EventManagerClass(kafkaBus);
   // or modify the exported singleton if desired

Notes:

• KafkaEventBus.publish is async and returns the producer send Promise.
• KafkaEventBus.subscribe starts a consumer and calls eventHandler.handle(event) for incoming messages.
• The current adapter is a starter implementation; for production you should refine consumer group/topic management and error handling.