mqtt

MQTT（ Message Queuing Telemetry Transport ，消息队列遥测传输协议），是一种基于发布/订阅（publish/subscribe）模式的"轻量级"通讯协议，该协议构建于TCP/IP协议上。MQTT最大优点在于，可以以极少的代码和有限的带宽，为连接远程设备提供实时可靠的消息服务。低开销、低带宽占用的即时通讯协议。

MQTT传输的消息分为：主题（Topic）和负载（payload）两部分：

1. Topic，可以理解为消息的类型，订阅者订阅（Subscribe）后，就会收到该主题的消息内容（payload）；
2. payload，可以理解为消息的内容，是指订阅者具体要使用的内容。

配合strophe.min.js 地址 (opens new window)

    <script src="./static/js/jquery-3.3.1.min.js"></script>
    <script src="./static/js/strophe.min.js"></script>

MQTT协议中的方法

1. Connect。等待与服务器建立连接。
2. Disconnect。等待MQTT客户端完成所做的工作，并与服务器断开TCP/IP会话。
3. Subscribe。等待完成订阅。
4. UnSubscribe。等待服务器取消客户端的一个或多个topics订阅。
5. Publish。MQTT客户端发送消息请求，发送完成后返回应用程序线程。

<script 
src="https://cdnjs.cloudflare.com/ajax/libs/paho-mqtt/1.0.1/mqttws31.min.js" 
type="text/javascript">
</script>
<script>
var mqtt=null;
var reconnectTimeout = 3000;
var host = 'xx.xxxxx.com'; // hostname or IP address
var port = 80xx;
var topic = '';
var useTLS = false;
var username = null;
var password = null;

//false时保留消息，实现离线消息功能
var cleansession = false;

function MQTTconnect() {
    try {
        username = newThis&&newThis.$store.state.selfmes.landline||'';
        password = "xxxxx";
        clientId = newThis&&newThis.$store.state.selfmes.landline;
        mqtt = new Paho.MQTT.Client(
        host,
        port,
        clientId);
        var options = {
        timeout: 3,
        useSSL: useTLS,
        cleanSession: cleansession,
        onSuccess: onConnect,
        onFailure: function (message) {
        newThis&&newThis.$message.error(
			`连接失败，请稍后再试，报错信息为:${message.errorMessage}`
		)
        // $('#status').val("Connection failed: " + message.errorMessage + "Retrying");
         setTimeout(MQTTconnect, reconnectTimeout);
        }
        };
      
        mqtt.onConnectionLost = onConnectionLost;
        mqtt.onMessageArrived = onMessageArrived;
        
        if (username != null) {
        options.userName = username;
        options.password = password;
        }
       
        mqtt.connect(options);
    } catch (error) {
        console.log('mqtt登录后再连接')
    }

}

function onConnect() {
    topic=`/aaaaa/${newThis.$store.state.selfmes.landline}`
    mqtt.subscribe(topic, {qos: 2});
}

function onConnectionLost(response) {
    console.log(response.errorMessage)
    setTimeout(MQTTconnect, reconnectTimeout);
 
};
//收到回复消息或者是告知发送消息成功了！
function onMessageArrived(message) {
    
    //拿到发送消息接受体
    // var payload =JSON.parse(message.payloadString)
    var temhtml;
   
    try {
        temhtml=JSON.parse(message.payloadString);
    } catch (error) {
        temhtml=message.payloadString;
        return;
    }
    let getmes=temhtml.content;
	......
};
  </script>

 let sendmes={
   	chatType:1,
   	content:this.qqtext,
   	from:that.$store.state.selfmes.landline,
   	contentType:0,
   	groupJid:this.qqroomid,
   	to: that.qqlandline,
   	groupName:that.qqtopic,
   	timeStamp:new Date().getTime(),
   	name:that.$store.state.selfmes.name,
   	photo:that.$store.state.selfmes.photo,

   }
  sendmes= JSON.stringify(sendmes)
  console.log(sendmes)
   let msg = $msg({
   	to: "receiver@wx.cintelcloud.com", 
   	from: that.$store.state.selfmes.jid, 
   	type: 'chat'
   }).c("body", null, sendmes);
   qconnection.send(msg.tree())