why redis pub sub is used code example

Example 1: redis custom pub sub

// SUBSCRIBER

import IORedis, { Redis } from 'ioredis'
import chalk from 'chalk'
import { Publisher } from '../utils/util.publisher'
import { ISubscriber } from '../interface/interface.subscriber'

export class Subscriber {
	private keyTo: string
	private keyFrom: string
	private uniqueId: string

	constructor(config: Readonly<ISubscriber>) {
		this.keyTo = config.key
		this.keyFrom = Publisher.get().key
		this.uniqueId = Publisher.get().unique
	}

	private redisConnect(): Redis {
		const ioRedis = new IORedis({
			host: '127.0.0.1',
			port: 6379,
			maxRetriesPerRequest: 50,
			connectTimeout: 5000,
			enableReadyCheck: true,
			enableAutoPipelining: true
		}) as Redis

		return ioRedis
	}

	public async getString(keyName: string): Promise<any> {
		if (this.keyTo == this.keyFrom) {
			const ioRedis = this.redisConnect() as Redis
			const response: string = await ioRedis.get(keyName)
			if (response) {
				return Promise.resolve(response)
			}
			return {}
		} else {
			return Promise.reject(chalk.red(new Error(`invalid key Subscriber: ${this.keyTo} and Publisher: ${this.keyFrom}`)))
		}
	}

	public async getMap(keyName: string): Promise<any> {
		if (this.keyTo == this.keyFrom) {
			const ioRedis = this.redisConnect() as Redis
			const response: Record<string, any> = await ioRedis.hgetall(keyName)
			if (response) {
				return Promise.resolve(JSON.parse(response.payload))
			}
			return {}
		} else {
			return Promise.reject(chalk.red(new Error(`invalid key Subscriber: ${this.keyTo} and Publisher: ${this.keyFrom}`)))
		}
	}

	public async getResponse(): Promise<any> {
		const ioRedis = this.redisConnect() as Redis
		const getEvent = await ioRedis.get(`response:speaker:${this.uniqueId}`)
		const response: Record<string, any> = await ioRedis.hgetall(`${getEvent}`)
		if (response) {
			return Promise.resolve(JSON.parse(response.response))
		}
		return {}
	}
}

Example 2: redis custom pub sub

// PUBLISHER

import IORedis, { Redis } from 'ioredis'
import { v4 as uuid } from 'uuid'
import { IPublisher } from '../interface/interface.publisher'

export class Publisher {
	private static key: string
	private static unique: string

	constructor(configs: Readonly<IPublisher>) {
		Publisher.key = configs.key
		Publisher.unique = uuid()
		Publisher.set({ key: configs.key, unique: Publisher.unique })
	}

	public static get(): Record<string, any> {
		const options: Record<string, any> = {
			key: Publisher.key,
			unique: Publisher.unique
		}
		return options
	}

	private static set(config: Record<string, any>): void {
		Publisher.key = config.key
		Publisher.unique = config.unique
	}

	private redisConnect(): Redis {
		const ioRedis = new IORedis({
			host: '127.0.0.1',
			port: 6379,
			maxRetriesPerRequest: 50,
			connectTimeout: 5000,
			enableReadyCheck: true,
			enableAutoPipelining: true
		}) as IORedis.Redis

		return ioRedis
	}

	public async setString(keyName: string, data: string): Promise<void> {
		const ioRedis = this.redisConnect() as Redis
		await ioRedis.set(keyName, data)
		await ioRedis.expire(keyName, 3)
	}

	public async setMap(keyName: string, data: Record<string, any>): Promise<void> {
		const ioRedis = this.redisConnect() as Redis
		await ioRedis.hset(keyName, { payload: JSON.stringify(data) })
		await ioRedis.expire(keyName, 3)
	}

	public async setResponse(keyName: string, data: Record<string, any>): Promise<void> {
		const ioRedis = this.redisConnect() as Redis
		await ioRedis.setex(`response:speaker:${Publisher.get().unique}`, 1, `response:speaker:${keyName}`)
		await ioRedis.hset(`response:speaker:${keyName}`, { response: JSON.stringify(data) })
		await ioRedis.expire(`response:speaker:${keyName}`, 3)
	}
}