         clientId: clientId
        },
        timeout: timeout,
        keepAliveInterval: keepAlive,
        cleanSession: cleanSession,
        useSSL: ssl,
        userName: userName,
        password: password,
        onSuccess: onConnect,
        onFailure: function (e) {
            console.log(e);
        }
    };

    function onConnect() {
        console.log("onConnected");
        client.subscribe("/topic_back");//订阅主题

        //发送消息
        message = new Paho.MQTT.Message("hel