time-diff-client

Connects to time-diff-server to calculate time diff with it, useful for time synchronization.

Use case

Let's say you want to run something on multiple clients with very low time difference between them. Start playing audio, for example.

time-diff-client will help you do that by allowing each client to calculate its time difference with the time server.

When all clients know their time difference with the time server you can instruct all clients to do stuff at server time, thus achieving a good level of synchrony.

Install

npm install --save time-diff-client

Usage

time-diff-client comes in two flavors:

• WebSockets
• UDP

UDP should be the preferred option because it normally has lower latency than WebSockets. But you can choose whichever is best suited for your use case.

UDP

const TimeClient = require('time-diff-client/udp')

// These are the default values.
const params = {
  port: 3025,
  maxIterations: 150,
  minPrecision: 5, // ms
  debug: true
}
const timeClient = new TimeClient(params)
timeClient
  .init()
  .onDiff((diff) => {
    console.log('TIME DIFF:', diff)
    process.exit()
  })

WebSockets

const TimeClient = require('time-diff-client/ws')

// These are the default values.
const params = {
  timeDiffServer: 'ws://localhost:8001',
  maxIterations: 150,
  minPrecision: 5, // ms
  debug: true
}
const timeClient = new TimeClient(params)
timeClient
  .init()
  .onDiff((diff) => {
    console.log('TIME DIFF:', diff)
    process.exit()
  })

Run test clients

These are test implementation of time-diff-client that connects to a time-diff-server instance and prints time diff to console.

The following params can be passed from the command line:

• DEBUG: Prints info to console. Default is true.
• PORT: Client port. Default is 3025. Only available on UDP mode.
• MAX_ITERATIONS: How many requests will be made to the time server. Default is 150.
• PRECISION: Min precision we're interested in, expressed in ms. Default is 5.
• TIME_SERVER_URL: URL to time-diff-server instance. Default is 'ws://localhost:8001'. There's no server for UDP, it uses local broadcast in this mode.

WebSockets client test:

node_modules/.bin/tdc-ws-test

Passing params:

PORT=3000 PRECISION=2 node_modules/.bin/tdc-ws-test

UDP client test:

node_modules/.bin/tdc-udp-test

Passing params:

PORT=3000 PRECISION=2 node_modules/.bin/tdc-udp-test

A better approach if you find yourself using this a lot is to add it to your npm scripts:

"scripts": {
  "tdc-ws-test": "tdc-ws-test",
  "tdc-udp-test": "tdc-udp-test"
}

And then run:

npm run tdc-ws-test

Or:

npm run tdc-udp-test

This commands will work directly if you install time-diff-client globally:

tdc-ws-test and tdc-udp-test.

Test

If you clone this repo and want to check code changes run:

npm test

Or:

npm run test-focus

Also run the test clients to ensure connection to time-diff-server still works OK.

Enjoy!