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Using event bus adapters

MemoryEventBusAdapter​

To use the MemoryEventBusAdapter you only need to create instance of it.

import { MemoryEventBusAdapter } from "@daiso-tech/core/event-bus/adapters";

const eventBusAdapter = new MemoryEventBusAdapter();

You can also provide an EventEmitter that will be used for dispatching the events in memory:

import { MemoryEventBusAdapter } from "@daiso-tech/core/event-bus/adapters";
import { EventEmitter } from "node:events";

const eventEmitter = new EventEmitter<any>();
const eventBusAdapter = new MemoryEventBusAdapter(eventEmitter);
info

MemoryEventBusAdapter lets you test your app without external dependencies like Redis, ideal for local development, unit tests, integration tests and fast E2E test for the backend application.

RedisPubSubEventBusAdapter​

To use the RedisPubSubEventBusAdapter, you'll need to:

  1. Install the required dependency: ioredis package
  2. Provide a string serializer (ISerde)
import { RedisPubSubEventBusAdapter } from "@daiso-tech/core/event-bus/adapters";
import { Serde } from "@daiso-tech/core/serde";
import { SuperJsonSerdeAdapter } from "@daiso-tech/core/serde/adapters";
import Redis from "ioredis";

const dispatcherClient = new Redis("YOUR_REDIS_CONNECTION_STRING");
const listenerClient = new Redis("YOUR_REDIS_CONNECTION_STRING");
const serde = new Serde(new SuperJsonSerdeAdapter());
const eventBusAdapter = new RedisPubSubEventBusAdapter({
    dispatcherClient,
    listenerClient,
    serde,
});
danger

Note you need to use two separate Redis clients:

  • One dedicated to listening/subscribing to events
  • Another dedicated to dispatching/publishing events

In Redis Pub/Sub, a connection becomes blocked while subscribed to channels. This means a single client cannot both publish and subscribe simultaneously. For more details, refer to the official Redis Pub/Sub documentation.

NoOpEventBusAdapter​

The NoOpEventBusAdapter is a no-operation implementation, it performs no actions when called.

import { NoOpEventBusAdapter } from "@daiso-tech/core/event-bus/adapters";

const noEventBusAdapter = new NoOpEventBusAdapter();
info

The NoOpEventBusAdapter is useful when you want to mock out or disable your EventBus class.