improves websocket connections

- enables multiple simultaneous websocket connections
- adds automatic reconnect on dropped websocket connection

app/ble/IndoorBikeDataCharacteristic.js

@@ -87,8 +87,6 @@ export default class IndoorBikeDataCharacteristic extends bleno.Characteristic {
         buffer.writeUInt16LE(0xFF, 13)
       }
       this._updateValueCallback(buffer)
-    } else {
-      log.debug('can not notify indoor bike data, no central subscribed')
     }
     return this.RESULT_SUCCESS
   }

app/ble/RowerDataCharacteristic.js

@@ -85,8 +85,6 @@ export default class RowerDataCharacteristic extends bleno.Characteristic {
         buffer.writeUInt16LE(0xFF, 16)
       }
       this._updateValueCallback(buffer)
-    } else {
-      log.debug('can not notify rower data, no central subscribed')
     }
     return this.RESULT_SUCCESS
   }

app/client/app.js

@@ -7,32 +7,48 @@
 */
 // eslint-disable-next-line no-unused-vars
 export function createApp () {
-  // use the native websocket implementation of browser to communicate with backend
-  // eslint-disable-next-line no-undef
-  const socket = new WebSocket(`ws://${location.host}`)
-
   const fields = ['strokesTotal', 'distanceTotal', 'caloriesTotal', 'power', 'splitFormatted', 'strokesPerMinute', 'durationTotal']
 
-  socket.addEventListener('open', function (event) {
+  initWebsocket()
-  })
-
-  socket.addEventListener('message', function (event) {
-    try {
-      const data = JSON.parse(event.data)
-
-      for (const [key, value] of Object.entries(data)) {
-        if (fields.includes(key)) {
-          document.getElementById(key).innerHTML = value
-        }
-      }
-    } catch (err) {
-      console.log(err)
-    }
-  })
-
   resetFields()
   requestWakeLock()
 
+  function initWebsocket () {
+  // use the native websocket implementation of browser to communicate with backend
+  // eslint-disable-next-line no-undef
+    const socket = new WebSocket(`ws://${location.host}`)
+
+    socket.addEventListener('open', (event) => {
+      console.log('websocket openend')
+    })
+
+    socket.addEventListener('error', (error) => {
+      console.log('websocket error', error)
+      socket.close()
+    })
+
+    socket.addEventListener('close', (event) => {
+      console.log('websocket closed, attempting reconnect')
+      setTimeout(() => {
+        initWebsocket()
+      }, 1000)
+    })
+
+    socket.addEventListener('message', (event) => {
+      try {
+        const data = JSON.parse(event.data)
+
+        for (const [key, value] of Object.entries(data)) {
+          if (fields.includes(key)) {
+            document.getElementById(key).innerHTML = value
+          }
+        }
+      } catch (err) {
+        console.log(err)
+      }
+    })
+  }
+
   async function requestWakeLock () {
     // use the Wake Lock API to prevent the screen from going to standby
     if (!('wakeLock' in navigator)) {

app/server.js

@@ -21,7 +21,6 @@ import { createRowingStatistics } from './engine/RowingStatistics.js'
 
 // sets the global log level
 log.setLevel(log.levels.INFO)
-let websocket
 // recordRowingSession('recordings/wrx700_2magnets.csv')
 const peripheral = createRowingMachinePeripheral({
   simulateIndoorBike: true
@@ -78,18 +77,14 @@ rowingStatistics.on('strokeFinished', (data) => {
     speed: data.speed
   }
 
-  if (websocket) {
+  notifyWebClients(metrics)
-    websocket.send(JSON.stringify(metrics))
-  }
   peripheral.notifyData(metrics)
 })
 
 rowingStatistics.on('durationUpdate', (data) => {
-  if (websocket) {
+  notifyWebClients({
-    websocket.send(JSON.stringify({
+    durationTotal: data.durationTotal
-      durationTotal: data.durationTotal
+  })
-    }))
-  }
 })
 
 const port = process.env.PORT || 80
@@ -104,7 +99,7 @@ server.listen(port)
 const wss = new WebSocket.Server({ server })
 
 wss.on('connection', function connection (ws) {
-  websocket = ws
+  log.debug('websocket client connected')
   ws.on('message', function incoming (data) {
     try {
       const message = JSON.parse(data)
@@ -118,18 +113,20 @@ wss.on('connection', function connection (ws) {
       log.error(err)
     }
   })
-/*
+  ws.on('close', function () {
-  ws.send(JSON.stringify({
+    log.debug('websocket client disconnected')
-    strokesTotal: 15,
+  })
-    distanceTotal: 206,
-    caloriesTotal: 51,
-    power: 174,
-    split: '02:30',
-    strokesPerMinute: 14
-  }))
-  */
 })
 
+function notifyWebClients (message) {
+  const messageString = JSON.stringify(message)
+  wss.clients.forEach(function each (client) {
+    if (client.readyState === WebSocket.OPEN) {
+      client.send(messageString)
+    }
+  })
+}
+
 /*
 const readInterface = readline.createInterface({
   input: fs.createReadStream('recordings/wrx700_2magnets.csv')
@@ -149,14 +146,15 @@ let simCalories = 0.0
 function simulateRowing () {
   const metrics = {
     strokesTotal: simStroke++,
-    distanceTotal: simDistance += 10.1,
+    distanceTotal: Math.round(simDistance += 10.1),
-    caloriesTotal: simCalories += 0.3,
+    caloriesTotal: Math.round(simCalories += 0.3),
-    power: 80 + 20 * (Math.random() - 0.5),
+    power: Math.round(80 + 20 * (Math.random() - 0.5)),
-    splitFormatted: 160 + 20 * (Math.random() - 0.5),
+    splitFormatted: '02:30',
-    split: 80 + 20 * (Math.random() - 0.5),
+    split: Math.round(80 + 20 * (Math.random() - 0.5)),
-    strokesPerMinute: 10 + 20 * (Math.random() - 0.5),
+    strokesPerMinute: Math.round(10 + 20 * (Math.random() - 0.5)),
-    speed: (15 + 20 * (Math.random() - 0.5)).toFixed(2)
+    speed: Math.round((15 + 20 * (Math.random() - 0.5)).toFixed(2))
   }
   peripheral.notifyData(metrics)
+  notifyWebClients(metrics)
 }
 */

doc/backlog.md

@@ -4,7 +4,6 @@ This is the very minimalistic Backlog for further development of this project.
 
 ## Soon
 
-* robust handling of websockets (reconnect, multiple connections)
 * handle training interruptions (set stroke specific metrics to "0" if no impulse detected for x seconds)
 * check todo markers in code and add them to this backlog
 * cleanup of the server.js start file