Example Socket for Emotiv EPOC+ Wireless EEG (emotiv.com/epoc)

socket.js

// Written by Jacob Schwartz, jaschwa@umich.edu, September 2018, edited & published May 2019

// In September 2018, I worked with the EPOC+ as part of a project for the MedHacks Hackathon. 
// It was extremely counterintuitive to work with, and if anyone else comes across issues with 
// it I figure this code might be helpful. It was awhile ago but I'd be willing to try to to help 
// if anyone experiences issues with the device - just open an issue on my project's repo 
// (github.com/jhschwartz/medhacks-zzg) and I'll see if I can help.

// EMOTIV docs: https://emotiv.github.io/cortex-docs/
// see https://github.com/jhschwartz/medhacks-zzg for my failed project that used the EPOC+

var token = 'YOUR-TOKEN-HERE'
var headset_id = 'YOUR-HEADSET-ID'

// Get references to elements on the page.
// Might not be useful to anyone else.
var form = document.getElementById('message-form')
var messageField = document.getElementById('message')
var messagesList = document.getElementById('messages')
var socketStatus = document.getElementById('status')
var closeBtn = document.getElementById('close')

// These IDs are how you jump into the websocket 
const ID_GET_USER_LOGIN = 1
const ID_AUTHORIZE = 2
const ID_LICENSE_ACCEPT = 3
const ID_QUERY_HEADSETS = 4
const ID_CREATE_SESSION = 5
const ID_UPDATE_SESSION = 6
const ID_QUERY_SESSIONS = 7
const ID_SUBSCRIBE = 8
const ID_OTHER = 999

// socket opens on load of the page 
var run_socket = (socket, streams) => {
  // Thanks SO user user3215378: https://stackoverflow.com/a/21394730/4176019
  function waitForSocketConnection(socket, callback) {
    setTimeout(
      function () {
          if (socket.readyState === 1) {
              console.log("Connection is made")
              if(callback != null){
                  callback()
              }
              return

          } else {
              console.log("wait for connection...")
              waitForSocketConnection(socket, callback)
          }

      }, 5) // wait 5 milisecond for the connection...
  }

  // connect socket
  var socket = new WebSocket('wss://emotivcortex.com:54321')
  
   // send user login on load
  waitForSocketConnection(socket, function() {
    socket.send(JSON.stringify({
      'jsonrpc': '2.0',
      'method': 'getUserLogin',
      'id': ID_GET_USER_LOGIN
    }))
  })

  // every time the socket receives data from the headset it includes an id
  // that corresponds to certain events defined in the consts (lines 24-32)
  socket.onmessage = function(event) {
    var data = JSON.parse(event.data)
    // the switch statement lets you go from a generic reception of a headset "message"
    // to specific methods defined in this file.
    switch (data['id']) {
      case ID_GET_USER_LOGIN:
        console.log('received user login')
        console.log(data)
        authorize()
        break
      case ID_AUTHORIZE:
        console.log('received authorize')
        console.log(data)
        token = data['result']['_auth']
        license(token)
        break
      case ID_LICENSE_ACCEPT:
        console.log('received license')
        console.log(data)
        query_headsets()
        break
      case ID_QUERY_HEADSETS:
        console.log('received query headsets')
        console.log(data)
        headset_id = data['result'][0]['id']
        console.log(headset_id)
        create_session(headset_id)
        break
      case ID_CREATE_SESSION:
        console.log('received create session')
        console.log(data)
        update_session()
        break
      case ID_UPDATE_SESSION:
        console.log('received update session')
        console.log(data)
        query_sessions()
        // break
      case ID_QUERY_SESSIONS:
        console.log('received query session')
        console.log(data)
        subscribe()
        break
      case ID_SUBSCRIBE:
        console.log('received subscribe')
        console.log(data)
        handle_message(data)
        break
      case ID_OTHER:
        console.log('received other')
        handle_message(data)
        break
      default:
        // default no id so we are collecting data -- this is specific to your project/where 
        // you get to do what you actually get to do something with the headset
        process_data(data)
    }
  }

  // specific parts of authorization, license, etc. are outlined by the EPOC+ docs.
  function authorize() {
    socket.send(JSON.stringify({
      'jsonrpc': '2.0',
      'method': 'authorize',
      'id': ID_AUTHORIZE,
      'params': {
        'username': username,
        'password': password,
        'client_id': client_id,
        'client_secret': client_secret
      }
    }))
  }

  function license(token) {
    console.log(token)
    socket.send(JSON.stringify({
      'jsonrpc': '2.0',
      'method': 'acceptLicense',
      'id': ID_LICENSE_ACCEPT,
      'params': {
        '_auth': token
      }
    }))
  }

  function query_headsets() {
    socket.send(JSON.stringify({
      'jsonrpc': '2.0',
      'method': 'queryHeadsets',
      'id': ID_QUERY_HEADSETS,
      'params': {
        'wilcard': 'EPOCPLUS-*'
      }
    }))
  }

  function create_session(headset_id) {
    socket.send(JSON.stringify({
      'jsonrpc': '2.0',
      'method': 'createSession',
      'id': ID_CREATE_SESSION,
      'params': {
        '_auth': token,
        'headset': headset_id,
        'status': 'open'
      }
    }))
  }

  function update_session() {
    socket.send(JSON.stringify({
      "jsonrpc": "2.0",
      "method": "updateSession",
      "params": {
        "_auth": token,
        "status": 'active'
      },
      "id": ID_UPDATE_SESSION
    }))
  }

  function query_sessions() {
    socket.send(JSON.stringify({
      'jsonrpc': '2.0',
      'method': 'querySessions',
      'id': ID_QUERY_SESSIONS,
      'params': {
        '_auth': token
      }
    }))
  }

  function subscribe() {
    socket.send(JSON.stringify({
      'jsonrpc': '2.0',
      'method': 'subscribe',
      'id': ID_SUBSCRIBE,
      'params': {
        '_auth': token,
        'streams': streams
      }
    }))
  }

  var handle_message = data => {
    console.log(data)
  }
 
// --- BELOW THIS LINE IS WHERE YOU ACTUALLY GET TO DO STUFF WITH THE HEADSET BEYOND JUST CONNECTING --- //
  
  // the stuff in data, like 'pow', 'time', 'eeg' are provided by the headset and were used by my project.
  

  var process_data = data => {
    // pow: band data
    // using this to interpret sleep
    // needs to be stored in sets for analysis
    if (data['pow'] != undefined) {
      var date = new Date()
      data['time'] = date.getTime()
      pow_data.push(data) // method was specific to my project
      update_pow(data) // method was specific to my project
    }

    // met: health metrics (stress, excitement, etc)
    // using this to associate with sleep
    // needs to be stored in sets for analysis
    if (data['met'] != undefined && data != undefined) {
      met_data.push(data) // method was specific to my project
      update_met(data) // method was specific to my project
    }

    // eeg: health metrics (stress, excitement, etc)
    // using this to associate with sleep
    // needs to be stored in sets for analysis
    if (data['eeg'] != undefined && data != undefined) {
      eeg_data.push(data) //  method was specific to my project
      update_eeg(data) // method was specific to my project
    }

    // mot: motion data
    // using this to look pretty/stand in for our lack of real-time eeg
    // needs to trigger an update event all the time
    if (data['pow'] != undefined) {
      update_mot(data) // method was specific to my project
    }
  }

  socket.onclose = function(event) {
    console.log('socket closed!')
  }
}