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}`)
})

Other examples

Check test cases.

Changelog

We're using the GitHub releases for changelog entries.

TODO

1. More tests
2. Typescript declaration
3. Benchmarks

Enable debug

export DEBUG=mimic-ws*

License

MIT