node.js - 如何检查 Azure IOT 中心发送器是否已停止使用 node.js 和 socket.io

Question

我有两个程序，一个发送者和一个接收者。发送者向 IOT Hub 上的设备发送一些消息，只要发送者发送这些消息，接收者就会收到这些消息。我正在使用 socket.io 将这些消息广播到连接的客户端。然而，当发送者停止时，接收者也会停止，但发送者发送的最后一条消息将无限广播，直到我关闭接收者或发送者再次启动并发送新消息。最后一条消息将被无限复制和广播。如何检查发送程序是否已停止？

这是发件人程序:

var clientFromConnectionString = require('azure-iot-device-mqtt').clientFromConnectionString;
var Message = require('azure-iot-device').Message;
var connectionString = 'conn_string'
var client = clientFromConnectionString(connectionString);

var avgTemperature = 20;

var printResult = function (err, res) {
    if (err) {
        console.log('send error: ' + err.toString());
        return;
    }
    console.log('send status: ' + res.constructor.name);
};

setInterval(function () {
    var currentTemperature = avgTemperature + (Math.random() * 10) - 2;
    var data = JSON.stringify({
        deviceId: 'test',
        temperature: currentTemperature,
        latitude: 50.286264,
        longitude: 19.104079,
        time: Date.now()
    });
    var message = new Message(data);
    console.log("Sending message: " + message.getData());
    client.sendEvent(message, printResult);
}, 5000);

这是接收者和向客户端广播的socket.io:

var app = require('express')();
var http = require('http').Server(app);
var io = require('socket.io')(http);
var EventHubClient = require('azure-event-hubs').Client;
var connectionString = 'conn_string'

var printError = function (err) {
    console.log(err.message);
};

var result;

var printMessage = function (message) {
    console.log('Message received: ');
    result = JSON.stringify(message.body);
    console.log('message: ' + result);
    /* io.on('connection', function(socket){


     socket.on('chat message', function(msg){

     io.emit('chat message', result);
  }); 
}); */

        console.log('');
};

count =0;

app.get('/', function(req, res){
  res.sendFile(__dirname + '/index.html');
});

io.on('connection', function(socket){
  console.log('user connected');
  socket.on('chat message', function(msg){

     io.emit('chat message', result);

  }); 
  socket.on('disconnect', function(){
    console.log('user disconnected');
      socket.removeAllListeners('disconnect');
      io.removeAllListeners('connection');
  });
});

var client = EventHubClient.fromConnectionString(connectionString);
client.open()
    .then(client.getPartitionIds.bind(client))
    .then(function (partitionIds) {
        return partitionIds.map(function (partitionId) {
            return client.createReceiver('$Default', partitionId, { 'startAfterTime' : Date.now()}).then(function(receiver) {
                console.log('Created partition receiver: ' + partitionId)
                receiver.on('errorReceived', printError);
                receiver.on('message', printMessage);
            });
        });
    })
    .catch(printError);


http.listen(3000, function(){
  console.log('listening on *:3000');
});

Answer 1

根据你的代码。每当发送方停止发送时，接收方将不会收到消息，而是等待发送方发送新消息。但是，如果您仍想检查，可以使用发件人消息的序列号或将 ID 与其关联以检查重复项。