Sample Websockets client

README.md

Introduction

This is a sample Websocket client to send random JSON payload to a Websockets server.

Installation

After cloning this gist, run the following commands.

npm init -y
npm i ws moment

Usage

Launch with the following command where wsUrl is a Websockets end-point (ws: or wss:) and frequency is rate of publication in milli-secods.

node index.js wsUrl frequency

index.js

const WebSocket = require('ws')
const mom = require('moment')

function getRandomValue(min, max) {
  return Math.floor(Math.random() * (max - min + 1) + min)
}

function getPayload() {
  let payload = {}

  let ts = mom().format('DD-MM-YYYYTHH:mm:ss.SSS')
  let data = []
  let alarms1 = []
  let alarms2 = []
  let alarms3 = []
  let pData = ""

  pData = getRandomValue(0, 200)
  data.push({
    paramName: "param1",
    paramData: pData
  })
  pData = getRandomValue(0, 20)
  data.push({
    paramName: "param2",
    paramData: pData
  })
  pData = getRandomValue(0, 5000)
  data.push({
    paramName: "param3",
    paramData: pData
  })

  alarms1.push(
    {paramName : "param4", paramState : "HIGH"}
  )
  alarms1.push(
    {paramName : "param5", paramState : "LOW"}
  )
  alarms1.push(
    {paramName : "param6", paramState : "MED"}
  )

  pData = getRandomValue(0, 5000),
  alarms2.push(
    {
      paramName: "param7",
      paramData: pData,
      paramState: "HIGH"}
  )
  pData = getRandomValue(0, 20),
  alarms2.push(
    {
      paramName: "param8",
      paramData: pData,
      paramState: "HIGH"}
  )
  pData = getRandomValue(0, 1000),
  alarms2.push(
    {
      paramName: "param9",
      paramData: pData,
      paramState: "HIGH"}
  )

  pData = getRandomValue(0, 5000)
  alarms3.push(
    {paramName : "param10", paramData : pData}
  )
  pData = getRandomValue(0, 20)
  alarms3.push(
    {paramName : "param11", paramData : pData}
  )
  pData = getRandomValue(0, 1000)
  alarms3.push(
    {paramName : "param12", paramData : pData}
  )

  payload = {
    ts: ts,
    data: data,
    alarms1: alarms1,
    alarms2: alarms2,
    alarms3: alarms3
  }
  return payload
}

function startClient(wsServer, frequency) {
  const ws = new WebSocket(wsServer)
  ws.on('open', function open() {
    setInterval(function() {
      ws.send(JSON.toString(getPayload()))
    }, frequency)
  })
}

if (process.argv.length < 4) {
  console.log(`USAGE: node index.js wsServer frequency`)
  process.exit(1)
}

startClient(process.argv[2], process.argv[3])