【Websocket X IoT】Node.js上でWebsocketネットワークを構築し、ラズパイ&Arduinoをシリアル通信でデータを受信してみる

            $ npm install websocket serialport
        

            const webSocketsServerPort = 41337;
const webSocketServer = require('websocket').server;
const http = require('http');
const server = http.createServer((request, response) => {
    // Not important for us.
    // We're writing WebSocket server, not HTTP server
});
const clients = [];

server.listen(webSocketsServerPort, () => {
    console.log((new Date()) + " Server is listening on port " + webSocketsServerPort);
});

const wsServer = new webSocketServer({httpServer: server});

// Event if the server recieved a request from a listed client
wsServer.on('request', (request) => {
    console.log((new Date()) + ' Connection from origin ' + request.origin + '.');
    const connection = request.accept(null, request.origin);
    console.log((new Date()) + ' Connection accepted.');

    const index = clients.push(connection) - 1;

    // Event when the server recieved message from clients
    connection.on('message', (message) => {
        if (message.type === 'utf8') {
            console.log('Received Message: ' + message.utf8Data);
        } else if (message.type === 'binary') {
            console.log('Received Binary Message of ' + message.binaryData.length + ' bytes');
        }
    });

    // Event when an user disconnected
    connection.on('close', (connection) => {
        console.log((new Date()) + " Peer " + connection.remoteAddress + " disconnected.");
        // Remove an user from the list of connected clients
        clients.splice(index, 1);
    });
});
        

            $ node server.js
Wed Jun 09 2021 02:54:08 GMT+0000 (Coordinated Universal Time) Server is listening on port 41337
        

            $ curl -o - --http1.1 --include \
    --no-buffer \
    --header "Connection: Upgrade" \
    --header "Upgrade: websocket" \
    --header "Host: 192.168.0.123:41337" \
    --header "Origin: http://192.168.0.123:41337" \
    --header "Sec-WebSocket-Key: SGVsbG8sIHdvcmxkIQ==" \
    --header "Sec-WebSocket-Version: 13" \
    http://192.168.0.123:41337/
#👇レスポンス
HTTP/1.1 101 Switching Protocols
Upgrade: websocket
Connection: Upgrade
Sec-WebSocket-Accept: qGEgH3En71di5rrssAZTmtRTyFk=
Origin: http://192.168.0.123:41337
�
        

            $ node server.js
Wed Jun 09 2021 02:54:08 GMT+0000 (Coordinated Universal Time) Server is listening on port 41337
Wed Jun 09 2021 02:54:21 GMT+0000 (Coordinated Universal Time) Connection from origin http://192.168.0.123:41337.
Wed Jun 09 2021 02:54:21 GMT+0000 (Coordinated Universal Time) Connection accepted.
Wed Jun 09 2021 02:54:41 GMT+0000 (Coordinated Universal Time) Peer undefined disconnected.
        

            const webSocketsServerPort = 41337;
const webSocketServer = require('websocket').server;
const http = require('http');
const server = http.createServer((request, response) => {});
const clients = [];

server.listen(webSocketsServerPort, () => {
    console.log((new Date()) + " Server is listening on port " + webSocketsServerPort);
});

const wsServer = new webSocketServer({httpServer: server});

//👇シリアル通信用のライブラリ読み込み
const SerialPort = require('serialport');
const Readline = require('@serialport/parser-readline');

//👇ゲスト上(Arduino側)のSerialデバイスに名前を合せる
const portName = '/dev/ttyUSB0';
//👇接続先(Arduino)のシリアルモデムを考慮
const sp = new SerialPort(portName, {
    baudRate: 9600,
    dataBits: 8,
    parity: 'none',
    stopBits: 1,
    flowControl: false,
});
//👇パーサクラスを指定
const parser = sp.pipe(new Readline());

// Event if the server recieved a request from a listed client
wsServer.on('request', (request) => {
    console.log((new Date()) + ' Connection from origin ' + request.origin + '.');
    const connection = request.accept(null, request.origin);
    console.log((new Date()) + ' Connection accepted.');

    const index = clients.push(connection) - 1;

    // Event when the server recieved message from clients
    connection.on('message', (message) => {
        if (message.type === 'utf8') {
            console.log('Received Message: ' + message.utf8Data);
            //👇クライアントから受け取った文字列をデバイスへリダイレクト
            sp.write(message.utf8Data, (err) => {
                if (err) {
                    return console.log('Error: ', err.message);
                }
                console.log('Utf8 data written over uart.');
            })
        } else if (message.type === 'binary') {
            console.log('Received Binary Message of ' + message.binaryData.length + ' bytes');
            //👇クライアントから受け取ったバイナリをデバイスへリダイレクト
            sp.write(message.binaryData, (err) => {
                if (err) {
                    return console.log('Error: ', err.message);
                }
                console.log('Byte data written over uart.');
            })
        }
    });

    // Event when an user disconnected
    connection.on('close', (connection) => {
        console.log((new Date()) + " Peer " + connection.remoteAddress + " disconnected.");
        // Remove an user from the list of connected clients
        clients.splice(index, 1);
    });
});

//👇ポート開放時の初期化処理
sp.on('open', ()=> {
    console.log('Open Serialport');
});

//👇データ(Arduino > ラズパイ)の受信
parser.on('data', (inp_) => {
    try {
        console.log(`Uart Msg: ${inp_}`);
        for (let i=0; i < clients.length; i++) {
            //👇接続中のすべてのwsクライアントへメッセージ送信
            clients[i].sendUTF(`Uart Msg: ${inp_}`);
        };
    } catch(e) {
        return;
    }
});
        

            $ node server.js
Sun Jun 13 2021 05:26:13 GMT+0000 (Coordinated Universal Time) Server is listening on port 41337
Open Serialport
Uart Msg: LED ON
Uart Msg: LED OFF
Uart Msg: LED ON
Uart Msg: LED OFF
Uart Msg: LED ON
#...以下略
        

            <!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        #display {
            width: 500px;
            height: 100px;
            font-size: 2em;
        }
    </style>
</head>
<body>
    <textarea id="display"></textarea>
    <script>
        const ws = new WebSocket('ws://192.168.0.248:41337');
        const display = document.getElementById('display');
        let currentData = {};
        ws.onmessage = (event) => {display.value = `${event.data}`;}
    </script>
</body>
</html>
        

            const WebSocketClient = require('websocket').client;
const client = new WebSocketClient();

//👇接続エラー時のイベント
client.on('connectFailed', (err) => {
    console.log('Connect Error: ' + err.toString());
});

//👇接続中のイベント
client.on('connect', (connection) => {
    console.log('WebSocket Client Connected...');

    //👇接続時のエラー
    connection.on('error', (err) => {
        console.log("Connection Error: " + err.toString());
    });

    //👇サーバーからのメッセージ受信時
    connection.on('message', (message) => {
        if (message.type === 'utf8') {
            console.log(`Received UTF8: ${message.utf8Data}`);
        } else if (message.type === 'binary') {
            console.log(`Received Binary: ${message.binaryData.length} Bytes`);
        }
    });

    //👇切断時のイベント
    connection.on('close', () => {
        console.log('Client Connection Closed');
    });
});

client.connect('ws://192.168.0.123:41337/');