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@boringnode/bus is a service bus implementation for Node.js. It is designed to be simple and easy to use.

Currently, it supports the following transports:

👉 Memory: A simple in-memory transport for testing purposes.
👉 Redis: A Redis transport for production usage.
👉 Mqtt: A Mqtt transport for production usage.

Table of Contents

• Installation
• Usage
• Retry Queue

Installation

npm install @boringnode/bus

Usage

The module exposes a manager that can be used to register buses.

import{BusManager}from'@boringnode/bus'import{redis}from'@boringnode/bus/transports/redis'import{mqtt}from'@boringnode/bus/transports/mqtt'import{memory}from'@boringnode/bus/transports/memory'constmanager=newBusManager({default: 'main',transports: {main: {transport: memory(),},redis: {transport: redis({host: 'localhost',port: 6379,}),},mqtt: {transport: mqtt({host: 'localhost',port: 1883,}),},}})

Once the manager is created, you can subscribe to channels and publish messages.

manager.subscribe('channel',(message)=>{console.log('Received message',message)})manager.publish('channel','Hello world')

By default, the bus will use the default transport. You can specify different transport by using the use method.

manager.use('redis').publish('channel','Hello world')manager.use('mqtt').publish('channel','Hello world')

Without the manager

If you don't need multiple buses, you can create a single bus directly by importing the transports and the Bus class.

import{Bus}from'@boringnode/bus'import{RedisTransport}from'@boringnode/bus/transports/redis'consttransport=newRedisTransport({host: 'localhost',port: 6379,})constbus=newBus(transport,{retryQueue: {retryInterval: '100ms'}})

Retry Queue

The bus also supports a retry queue. When a message fails to be published, it will be moved to the retry queue.

For example, your Redis server is down.

constmanager=newBusManager({default: 'main',transports: {main: {transport: redis({host: 'localhost',port: 6379,}),retryQueue: {retryInterval: '100ms'}},}})manager.use('redis').publish('channel','Hello World')

The message will be moved to the retry queue and will be retried every 100ms.

You have multiple options to configure the retry queue.

exportinterfaceRetryQueueOptions{// Enable the retry queue (default: true)enabled?: boolean// Defines if we allow duplicates messages in the retry queue (default: true)removeDuplicates?: boolean// The maximum size of the retry queue (default: null)maxSize?: number|null// The interval between each retry (default: false)retryInterval?: Duration|false}

Test helpers

The module also provides some test helpers to make it easier to test the code that relies on the bus. First, you can use the MemoryTransport to create a bus that uses an in-memory transport.

You can also use the ChaosTransport to simulate a transport that fails randomly, in order to test the resilience of your code.

import{Bus}from'@boringnode/bus'import{ChaosTransport}from'@boringnode/bus/test_helpers'constbuggyTransport=newChaosTransport(newMemoryTransport())constbus=newBus(buggyTransport)/** * Now, every time you will try to publish a message, the transport  * will throw an error. */buggyTransport.alwaysThrow()