Question

我是javascript和mqtt的新手。我使用完成的api获取主题，然后将其传递以读取来自该主题的消息。问题是，尽管我确定该主题中只有一条消息，但我每次都会收到越来越多相同的消息，而不是一条消息

我创建了一个仅用于获取ID（主题）的脚本，而创建了第二个没有异步/等待从主题中读取的脚本，我们手动输入该脚本，然后一切正常

const axios = require('axios');
var mqtt = require('mqtt');
const BASE_URL = 'http://localhost:4000';
var client = mqtt.connect("mqtt://test.mosquitto.org")

const params = {
  "message": "subscribe"
}

let globalTopic;

// Use some API, for creating topic for mqtt, id is our topic
const configuration = async(params) => {
  const response = await axios.post(`${BASE_URL}/mqtt`, params);
  console.log(response.data)
  const { id } = response.data;
  console.log("id", id)
  return id;
} //configuration


// connect to mqtt-broker
const subscription = async(topic) => {

  console.log("topic", topic)

  client.on('connect', function() {
    console.log("connected")
    client.subscribe(topic, function(err) {
      if (err) {
        console.log("Can't connect" + err);
        process.exit(1);
      }
    })
  })
} // subscription

// try to get messages from topic
const readMessage = async(topic) => {
  client.on('message', function(topic, message) {
    console.log("message is " + message);
  });
}

// call all function
const main = async(params) => {
  globalTopic = await configuration(params)
  await subscription(globalTopic);
  await readMessage(globalTopic);
}

main(params);

configuration(params)和subscription(globalTopic)可以正常工作。 readMessage的 client.on 中执行了多次

如何排除来自mqtt的多条消息

0 个答案: