Mimic-ws NPM | npm.io

mimic-ws

Mimic-ws is drop-in replacement for ws, powered by uWebSockets.js

Note: This module does not work in the browser.

Installing

npm install mimic-ws

Been a drop-in replacement, `mimic-ws` has some limits and difference:

For SSL initialization you don't need separate HTTP server, just define certificate and key parameters, check examples.
clientTracking is always true, and wss.clients is a Map, key is unique id, each ws has the same unique attribute id. No need to code own logic.
Added backpressure event, so you can check that websocket is slow.
Added drain event, so you can check that websocket buffer is free.
Added publish/subscribe functions with MQTT topics support, check examples
WebSocket handlers like onclose/onerror are removed. Use events.
Use idleTimeout for dropping connections.
Use maxBackpressure for dropping slow consumers.
verifyClient parameters are bit different.

Usage examples

Simple server

const WebSocket = require('mimic-ws')

const wss = new WebSocket.Server({
    port: 8080
})

wss.on('connection', (ws) => {
    ws.on('message', (message) => {
        console.log('received: %s', message)
    })

    ws.send('something')
})

SSL server

const WebSocket = require('mimic-ws')

const wss = new WebSocket.Server({
    port: 8080,
    sslCert: './test/fixtures/cert.pem',
    sslKey: './test/fixtures/key.pem',
})

wss.on('connection', (ws) => {
    ws.on('message', (message) => {
        console.log('received: %s', message)
    })

    ws.send('something')
})

Server broadcast old school

A client WebSocket broadcasting to all connected WebSocket clients, including itself.

const WebSocket = require('mimic-ws')

const wss = new WebSocket.Server({
    port: 8080
})

wss.on('connection', (ws) => {
    ws.on('message', (data) => {
        wss.clients.forEach((client) => {
            client.send(data)
        })
    })
})

A client WebSocket broadcasting to every other connected WebSocket clients, excluding itself.

const WebSocket = require('mimic-ws')

const wss = new WebSocket.Server({
    port: 8080
})

wss.on('connection', (ws) => {
    ws.on('message', (data) => {
        wss.clients.forEach((client, id) => {
            if (ws !== client) { // or if (id.localeCompare(ws.id))
                client.send(data)
            }
        })
    })
})

Server broadcast pub/sub using MQTT topics

const WebSocket = require('mimic-ws')

const wss = new WebSocket.Server({
    port: 8080
})

wss.on('connection', (ws) => {
    ws.subscribe('/house/#')

    ws.publish('/house/room1')
    ws.publish('/house/room2')
})

Simple app using pub/sub JSON protocol

const WebSocket = require('mimic-ws')

const wss = new WebSocket.Server({
    port: 8080
})

const handle = (ws, msg) => {
    if (msg && msg.action) {
        switch (msg.action) {
            case 'publish':
                ws.publish(msg.topic, JSON.stringify(msg.data))
                break

            case 'subscribe':
                console.log(msg)
                ws.subscribe(msg.topic)
                break

            case 'unsubscribe':
                ws.unsubscribe(msg.topic)
                break

            default:
                console.error(`Unknown action: ${msg.action}`)
        }
    }
}

wss.on('connection', (ws) => {
    ws.on('message', (message) => {
        const msg = JSON.parse(message)
        handle(ws, msg)
    })
})

const publisher = new WebSocket(`ws://localhost:${wss.address().port}`)
publisher.on('open', () => {
    setInterval(() => {
        const msg = {
            action: 'publish',
            topic: '/house/room1',
            data: {
                title: 'temperature in room1',
                value: Math.floor(Math.random() * 30),
                timestamp: Date.now()
            }
        }
        publisher.send(JSON.stringify(msg))

        const msg2 = {
            action: 'publish',
            topic: '/house/room2',
            data: {
                title: 'temperature in room2',
                value: Math.floor(Math.random() * 30),
                timestamp: Date.now()
            }
        }
        publisher.send(JSON.stringify(msg2))
    }, 1000)
})

const subscriber = new WebSocket(`ws://localhost:${wss.address().port}`)
subscriber.on('open', () => {
    const msg = {
        action: 'subscribe',
        topic: '/house/#'
    }
    subscriber.send(JSON.stringify(msg))
})

subscriber.on('message', (message) => {
    console.log(`got message: ${message}`)
})