[JavaScript知识库]mqtt demo

1.Installing via EMQX Docker Image

docker run -d --name emqx -p 1883:1883 -p 8081:8081 -p 8083:8083 -p 8084:8084 -p 8883:8883 -p 18083:18083 emqx/emqx:4.4.1

2.接下来可以访问 仪表盘（dashboard）：

??????http://localhost:18083/

?可以在

etc/plugins/emqx_dashboard.conf

找到用户名密码：admin/public

##--------------------------------------------------------------------
## EMQ X Dashboard
##--------------------------------------------------------------------

## Default user's login name.
##
## Value: String
dashboard.default_user.login = admin

## Default user's password.
##
## Value: String
dashboard.default_user.password = public

Dashboard | EMQX Documentation

3. 安装mqtt库

访问mqtt 可以才有nodejs ，或者其他客户端，这里才有nodejs访问

npm install mqtt

4. 创建send_receiver.js

var mqtt = require("mqtt");



const clientId = 'mqttjs_' + Math.random().toString(16).substr(2, 8)

//const host = 'ws://broker.emqx.io:8083/mqtt'
const host = 'ws://localhost:8083/mqtt'
// const host = 'wss://localhost:8084/mqtt'



const topic = 'WillMsg'
const options = {
  keepalive: 60,
  clientId: clientId,
  protocolId: 'MQTT',
  protocolVersion: 4,
  clean: true,
  reconnectPeriod: 1000,
  connectTimeout: 30 * 1000,
  will: {
    topic: topic,
    payload: 'Connection Closed abnormally..!',
    qos: 0,
    retain: false
  },
}



console.log('Connecting mqtt client')
const client = mqtt.connect(host, options)
console.log('Connecting mqtt client end')

client.on('connect',()=>{
    console.log('Client connected:' + clientId)
    // Subscribe
    client.subscribe(topic, { qos: 0 })
})
client.on('error', (err) => {
  console.log('Connection error: ', err)
  client.end()
})

client.on('reconnect', () => {
  console.log('Reconnecting...')
})


// Received
client.on('message', (topic, message, packet) => {
  console.log('Received Message: ' + message.toString() + '\nOn topic: ' + topic)
})

5.创建receiver.js

var mqtt = require("mqtt");



const clientId = 'mqttjs_' + Math.random().toString(16).substr(2, 8)

//const host = 'ws://broker.emqx.io:8083/mqtt'
const host = 'ws://localhost:8083/mqtt'
// const host = 'wss://localhost:8084/mqtt'



const topic = 'WillMsg'
const options = {
  keepalive: 60,
  clientId: clientId,
  protocolId: 'MQTT',
  protocolVersion: 4,
  clean: true,
  reconnectPeriod: 1000,
  connectTimeout: 30 * 1000,
  will: {
    topic: topic,
    payload: 'Connection Closed abnormally..!',
    qos: 0,
    retain: false
  },
}



console.log('Connecting mqtt client')
const client = mqtt.connect(host, options)
console.log('Connecting mqtt client end')

client.on('connect',()=>{
    console.log('Client connected:' + clientId)
    // Subscribe
    client.subscribe(topic, { qos: 0 })
})
client.on('error', (err) => {
  console.log('Connection error: ', err)
  client.end()
})

client.on('reconnect', () => {
  console.log('Reconnecting...')
})


// Received
client.on('message', (topic, message, packet) => {
  console.log('Received Message: ' + message.toString() + '\nOn topic: ' + topic)
})

6.运行测试：

% node receiver.js 
Debugger listening on ws://127.0.0.1:60111/099b6f06-dcae-4510-84eb-504d6babf056
For help, see: https://nodejs.org/en/docs/inspector
Debugger attached.
Connecting mqtt client
Connecting mqtt client end
Client connected:mqttjs_077f092a

运行send_receiver.js

% node send_receiver.js
Connecting mqtt client
Connecting mqtt client end
Client connected:mqttjs_077f092a
Received Message: After Client connected:mqttjs_ae0c3a83
On topic: WillMsg
client2 Received Message: After Client connected:mqttjs_ae0c3a83
On topic: WillMsg

% node recever.js 
Debugger listening on ws://127.0.0.1:60111/099b6f06-dcae-4510-84eb-504d6babf056
For help, see: https://nodejs.org/en/docs/inspector
Debugger attached.
Connecting mqtt client
Connecting mqtt client end
Client connected:mqttjs_077f092a
Received Message: { "msg": "Hello, World41111!" }
On topic: WillMsg
Received Message: After Client connected:mqttjs_ae0c3a83
On topic: WillMsg

参考：

https://github.com/emqx/emqx

Dashboard | EMQX Documentation

Connect to MQTT broker with Websocket | EMQ