Summary

Step By Step

1. Create products and devices

2. Add script

3. The device simulates uplink data through a custom Topic

import com.alibaba.taro.AliyunIoTSignUtil;
import com.google.common.util.concurrent.ThreadFactoryBuilder;
import org.eclipse.paho.client.mqttv3.*;
import org.eclipse.paho.client.mqttv3.persist.MemoryPersistence;
import java.util.HashMap;
import java.util.Map;
import java.util.concurrent.ScheduledExecutorService;
import java.util.concurrent.ScheduledThreadPoolExecutor;
import java.util.concurrent.TimeUnit;

// Transmission equipment test
public class IoTDemoPubSubDemoForPersonalTopic {

    // Device triple information
    public static String productKey = "a1wJG******";
    public static String deviceName = "Device1";
    public static String deviceSecret = "40YEyiGzXmvhDdpvbUVFCHjC********";
    public static String regionId = "cn-shanghai";

    private static String pubTopic = "/"+ productKey + "/" + deviceName  + "/user/update?_sn=default";//Script analysis of custom Topic
    private static MqttClient mqttClient;

    public static void main(String [] args){

        initAliyunIoTClient(); // Initialize Client
        ScheduledExecutorService scheduledThreadPool = new ScheduledThreadPoolExecutor(1,
                new ThreadFactoryBuilder().setNameFormat("thread-runner-%d").build());

        scheduledThreadPool.scheduleAtFixedRate(()->postDeviceProperties(), 10,10, TimeUnit.SECONDS);
    }

    /**
     * Initialize Client object
     */
    private static void initAliyunIoTClient() {

        try {
            // Parameters required to construct a connection
            String clientId = "java" + System.currentTimeMillis();
            Map<String, String> params = new HashMap<>(16);
            params.put("productKey", productKey);
            params.put("deviceName", deviceName);
            params.put("clientId", clientId);
            String timestamp = String.valueOf(System.currentTimeMillis());
            params.put("timestamp", timestamp);
            // cn-shanghai
            String targetServer = "tcp://" + productKey + ".iot-as-mqtt."+regionId+".aliyuncs.com:1883";

            String mqttclientId = clientId + "|securemode=3,signmethod=hmacsha1,timestamp=" + timestamp + "|";
            String mqttUsername = deviceName + "&" + productKey;
            String mqttPassword = AliyunIoTSignUtil.sign(params, deviceSecret, "hmacsha1");

            connectMqtt(targetServer, mqttclientId, mqttUsername, mqttPassword);

        } catch (Exception e) {
            System.out.println("initAliyunIoTClient error " + e.getMessage());
        }
    }

    public static void connectMqtt(String url, String clientId, String mqttUsername, String mqttPassword) throws Exception {

        MemoryPersistence persistence = new MemoryPersistence();
        mqttClient = new MqttClient(url, clientId, persistence);
        MqttConnectOptions connOpts = new MqttConnectOptions();
        // MQTT 3.1.1
        connOpts.setMqttVersion(4);
        connOpts.setAutomaticReconnect(false);
        connOpts.setCleanSession(true);

        connOpts.setUserName(mqttUsername);
        connOpts.setPassword(mqttPassword.toCharArray());
        connOpts.setKeepAliveInterval(60);

        mqttClient.connect(connOpts);
    }

    /**
     * Reporting attributes
     */
    private static void postDeviceProperties() {

        try {
            //Reporting data
            System.out.println("custom Topic Escalation attribute value");
            //0x000000000100320100000000
            String hexString = "000000000100320100000000";
            byte[] payLoad = hexToByteArray(hexString);
            MqttMessage message = new MqttMessage(payLoad);
            message.setQos(0);
            mqttClient.publish(pubTopic, message);
        } catch (Exception e) {
            System.out.println(e.getMessage());
        }
    }

    /**
     * hex String to byte array
     * @param inHex Hex string to be converted
     * @return  Converted byte array result
     */
    public static byte[] hexToByteArray(String inHex){
        int hexlen = inHex.length();
        byte[] result;
        if (hexlen % 2 == 1){
            //Odd number
            hexlen++;
            result = new byte[(hexlen/2)];
            inHex="0"+inHex;
        }else {
            //Even numbers
            result = new byte[(hexlen/2)];
        }
        int j=0;
        for (int i = 0; i < hexlen; i+=2){
            result[j]=hexToByte(inHex.substring(i,i+2));
            j++;
        }
        return result;
    }

    /**
     * Hex String to byte
     * @param inHex Hex string to be converted
     * @return  Converted byte s
     */
    public static byte hexToByte(String inHex) {
        return (byte) Integer.parseInt(inHex, 16);
    }
}

4. Uplink message view

5. Precautions

1. When creating a user-defined Topic on the Internet of things platform, it is defined as a normal Topic without adding the parsing tag;
2. Only analyze the data reported by the device in the cloud, not the downlink data in the cloud;
3. Only the payloads of the reported data are parsed, and the parsed payloads are returned;
4. Before and after analysis, the Topic of data remains unchanged. For example, the data sent by the device to / ${productKey}/${deviceName}/user/update is still in the Topic after parsing.

Reference link

Overview of custom data analysis Topic

LoRaWAN device data analysis and open source MQTT SDK device end simulation