IoT Platform:Connect a sub-device to IoT Platform

Step 1: Manage the topological relationship

After the gateway connects to IoT Platform, it must synchronize the topological relationship with IoT Platform. This allows the gateway to proxy communication between the sub-device and IoT Platform. You can view and add the topological relationship on the console or by using the sample code.

• On the IoT Platform console, under the corresponding , view and add the topological relationship between the gateway and the sub-device.
  1. In the left-side navigation pane, choose Device Management > Devices, and find the gateway device in the list.
  2. Click Sub-device in the gateway's row to go to the sub-device management page. View the information about the gateway's sub-devices.
  3. Click Add Sub-device to add the sub-device that you created in the Create a gateway and a sub-device step.
• Use the following sample code to query and add the topological relationship.

  • Query the topological relationship:

         /**
         * Get the topological relationship for the gateway to check if one already exists between the gateway and a sub-device.
         */
        private void getGWDeviceTopo() {
            LinkKit.getInstance().getGateway().gatewayGetSubDevices(new IConnectSendListener() {
                @Override
                public void onResponse(ARequest request, AResponse aResponse) {
                    ALog.i(TAG, "Successfully retrieved the topological relationship for the gateway: " + JSONObject.toJSONString(aResponse));
                    // Get the list of sub-devices.
                    try {
                        ResponseModel<List<DeviceInfo>> response = JSONObject.parseObject(aResponse.data.toString(), new TypeReference<ResponseModel<List<DeviceInfo>>>() {
                        }.getType());
                        // TODO: Process the data based on your business scenario.
                    } catch (Exception e) {
                        e.printStackTrace();
                    }
                }
                @Override
                public void onFailure(ARequest request, AError error) {
                    ALog.i(TAG, "Failed to retrieve the topological relationship for the gateway: " + JSONObject.toJSONString(error));
                }
            });
        }

  • Add a topological relationship:

    Note

    • The next step explains how to obtain the device certificate for a sub-device.
    • After IoT Platform confirms the topological relationship between the sub-device and the gateway, the sub-device can go online and reuse the gateway's physical channel to communicate with IoT Platform.

        /**
         * Information about the sub-device for which to add the topological relationship.
         */
        private void gatewayAddSubDevice() {
            BaseInfo baseInfo1 = new BaseInfo();
            baseInfo1.productKey = "a1j7SyR****";
            baseInfo1.deviceName = "safa***";
            String deviceSecret = "7lzCJIWHmGFpZpDKbJdVucDHUz6C****";
            LinkKit.getInstance().getGateway().gatewayAddSubDevice(baseInfo1, new ISubDeviceConnectListener() {
                @Override
                public String getSignMethod() {
                    // The signing method to use.
                    return "hmacsha1";
                }
                @Override
                public String getSignValue() {
                    // Get the signature. The user uses the deviceSecret to generate the signature.
                    Map<String, String> signMap = new HashMap<>();
                    signMap.put("productKey", baseInfo1.productKey);
                    signMap.put("deviceName", baseInfo1.deviceName);
                    //signMap.put("timestamp", String.valueOf(System.currentTimeMillis()));
                    signMap.put("clientId", getClientId());
                    return SignUtils.hmacSign(signMap, deviceSecret);
                }
                @Override
                public String getClientId() {
                    // The clientId can be any string.
                    return "id";
                }
                @Override
                public Map<String, Object> getSignExtraData() {
                    return null;
                }
                @Override
                public void onConnectResult(boolean isSuccess, ISubDeviceChannel iSubDeviceChannel, AError aError) {
                    // Result of the add operation.
                    if (isSuccess) {
                        // The sub-device is added. You can now proceed to log in the sub-device.
                        ALog.i(TAG, "Successfully added the topological relationship: " + JSONObject.toJSONString(iSubDeviceChannel));
                        //Log in the sub-device.
                        gatewaySubDeviceLogin();
                    } else {
                        ALog.i(TAG, "Failed to add the topological relationship: " + JSONObject.toJSONString(aError));
                    }
                }
                @Override
                public void onDataPush(String s, AMessage aMessage) {
                }
            });
        }

Step 2: Obtain sub-device certificate

Step 3: Log in a sub-device

     /**
     * Before you call the API to log in the sub-device, make sure the topological relationship is established. After the gateway discovers a connected sub-device, it must notify IoT Platform that the sub-device is online.
     * After the sub-device is online, you can perform operations such as subscribing to topics and publishing messages.
     */
    public void gatewaySubDeviceLogin(){
        BaseInfo baseInfo1 = new BaseInfo();
        baseInfo1.productKey = "a1j7SyR****";
        baseInfo1.deviceName = "safasdf";
        LinkKit.getInstance().getGateway().gatewaySubDeviceLogin(baseInfo1, new ISubDeviceActionListener() {
            @Override
            public void onSuccess() {
                // The sub-device is logged in by proxy.
                // After the sub-device is online, you can subscribe to topics, publish messages, and delete or disable the sub-device.
                // subDevDisable(null);
                // subDevDelete(null);
            }
            @Override
            public void onFailed(AError aError) {
                ALog.d(TAG, "onFailed() called with: aError = [" + aError + "]");
            }
        });
    }
}

Appendix: Code demo

The following code demonstrates how a gateway discovers and reports sub-device information, establishes a logical channel between the sub-device and IoT Platform, and allows the sub-device to reuse the gateway's physical channel to connect to IoT Platform:

package com.aliyun.iot.api.common.deviceApi;
import com.alibaba.fastjson.JSONObject;
import com.alibaba.fastjson.TypeReference;
import com.aliyun.alink.dm.api.BaseInfo;
import com.aliyun.alink.dm.api.DeviceInfo;
import com.aliyun.alink.dm.api.InitResult;
import com.aliyun.alink.dm.api.SignUtils;
import com.aliyun.alink.dm.model.ResponseModel;
import com.aliyun.alink.linkkit.api.ILinkKitConnectListener;
import com.aliyun.alink.linkkit.api.IoTMqttClientConfig;
import com.aliyun.alink.linkkit.api.LinkKit;
import com.aliyun.alink.linkkit.api.LinkKitInitParams;
import com.aliyun.alink.linksdk.channel.gateway.api.subdevice.ISubDeviceActionListener;
import com.aliyun.alink.linksdk.channel.gateway.api.subdevice.ISubDeviceChannel;
import com.aliyun.alink.linksdk.channel.gateway.api.subdevice.ISubDeviceConnectListener;
import com.aliyun.alink.linksdk.channel.gateway.api.subdevice.ISubDeviceRemoveListener;
import com.aliyun.alink.linksdk.cmp.core.base.AMessage;
import com.aliyun.alink.linksdk.cmp.core.base.ARequest;
import com.aliyun.alink.linksdk.cmp.core.base.AResponse;
import com.aliyun.alink.linksdk.cmp.core.listener.IConnectSendListener;
import com.aliyun.alink.linksdk.tools.AError;
import com.aliyun.alink.linksdk.tools.ALog;
import java.util.*;
import static com.aliyun.alink.linksdk.tools.ALog.LEVEL_DEBUG;
public class DeviceTopoManager {
    private static String regionId = "cn-shanghai";
    private static final String TAG = "TOPO";
    // Gateway device
    private static String GWproductKey = "a1Bxp*********";
    private static String GWdeviceName = "XMtrv3y*************";
    private static String GWdeviceSecret = "19xJNybifnmgc*************";
    public static void main(String[] args) {
        /**
         * MQTT connection information.
         */
        DeviceTopoManager manager = new DeviceTopoManager();
        /**
         * The server-side Java HTTP client uses TLSv1.2.
         */
        System.setProperty("https.protocols", "TLSv1.2");
        manager.init();
    }
    public void init() {
        LinkKitInitParams params = new LinkKitInitParams();
        /**
         * Set MQTT initialization parameters.
         */
        IoTMqttClientConfig config = new IoTMqttClientConfig();
        config.productKey = GWproductKey;
        config.deviceName = GWdeviceName;
        config.deviceSecret = GWdeviceSecret;
        config.channelHost = GWproductKey + ".iot-as-mqtt." + regionId + ".aliyuncs.com:1883";
        /**
         * Specifies whether to receive offline messages.
         * This corresponds to the cleanSession field in MQTT.
         */
        config.receiveOfflineMsg = false;
        params.mqttClientConfig = config;
        ALog.setLevel(LEVEL_DEBUG);
        ALog.i(TAG, "mqtt connection info=" + params);
        /**
         * Set initialization parameters and pass in the device certificate of the gateway.
         */
        DeviceInfo deviceInfo = new DeviceInfo();
        deviceInfo.productKey = GWproductKey;
        deviceInfo.deviceName = GWdeviceName;
        deviceInfo.deviceSecret = GWdeviceSecret;
        params.deviceInfo = deviceInfo;
        /**Initialize the LinkKit instance and establish a connection.**/
        LinkKit.getInstance().init(params, new ILinkKitConnectListener() {
            public void onError(AError aError) {
                ALog.e(TAG, "Init Error error=" + aError);
            }
            public void onInitDone(InitResult initResult) {
                ALog.i(TAG, "onInitDone result=" + initResult);
                // Get the topological relationship for the gateway to check if one already exists between the gateway and the sub-device.
                // If a relationship exists, log in the sub-device directly.
                getGWDeviceTopo();
                // Use dynamic registration to obtain the DeviceSecret for the sub-device. If the device certificate is known, skip this step and add the topological relationship directly.
                // When you create the device on IoT Platform in advance, you can use its MAC address or serial number (SN) as the DeviceName.
                gatewaySubDevicRegister();
                // Information about the sub-device for which to add the topological relationship.
                gatewayAddSubDevice();
            }
        });
    }
    /**
     * Get the topological relationship for the gateway to check if one already exists between the gateway and a sub-device.
     */
    private void getGWDeviceTopo() {
        LinkKit.getInstance().getGateway().gatewayGetSubDevices(new IConnectSendListener() {
            @Override
            public void onResponse(ARequest request, AResponse aResponse) {
                ALog.i(TAG, "Successfully retrieved the topological relationship for the gateway: " + JSONObject.toJSONString(aResponse));
                // Get the list of sub-devices.
                try {
                    ResponseModel<List<DeviceInfo>> response = JSONObject.parseObject(aResponse.data.toString(), new TypeReference<ResponseModel<List<DeviceInfo>>>() {
                    }.getType());
                    // TODO: Process the data based on your business scenario.
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
            @Override
            public void onFailure(ARequest request, AError error) {
                ALog.i(TAG, "Failed to retrieve the topological relationship for the gateway: " + JSONObject.toJSONString(error));
            }
        });
    }
    /**
     * Use dynamic registration to obtain the deviceSecret for a sub-device. If the gateway has already obtained the device certificate for the sub-device, skip this step.
     * When you create the device on IoT Platform in advance, you can use its MAC address or serial number (SN) as the DeviceName.
     */
    private void gatewaySubDevicRegister() {
        List<BaseInfo> subDevices = new ArrayList<>();
        BaseInfo baseInfo1 = new BaseInfo();
        baseInfo1.productKey = "a1j7SyR**********";
        baseInfo1.deviceName = "test123*********";
        subDevices.add(baseInfo1);
        LinkKit.getInstance().getGateway().gatewaySubDevicRegister(subDevices, new IConnectSendListener() {
            @Override
            public void onResponse(ARequest request, AResponse response) {
                ALog.i(TAG, "Sub-device registered successfully: " + JSONObject.toJSONString(response));
            }
            @Override
            public void onFailure(ARequest request, AError error) {
                ALog.i(TAG, "Failed to register the sub-device: " + JSONObject.toJSONString(error));
            }
        });
    }
    /**
     * Adds the topological relationship for a sub-device.
     */
    private void gatewayAddSubDevice() {
        BaseInfo baseInfo1 = new BaseInfo();
        baseInfo1.productKey = "a1j7Sy*************";
        baseInfo1.deviceName = "safasd********";
        String deviceSecret = "7lzCJIWHmGF**************";
        LinkKit.getInstance().getGateway().gatewayAddSubDevice(baseInfo1, new ISubDeviceConnectListener() {
            @Override
            public String getSignMethod() {
                // The signing method to use.
                return "hmacsha1";
            }
            @Override
            public String getSignValue() {
                // Get the signature. The user uses the DeviceSecret to generate the signature.
                Map<String, String> signMap = new HashMap<>();
                signMap.put("productKey", baseInfo1.productKey);
                signMap.put("deviceName", baseInfo1.deviceName);
//                signMap.put("timestamp", String.valueOf(System.currentTimeMillis()));
                signMap.put("clientId", getClientId());
                return SignUtils.hmacSign(signMap, deviceSecret);
            }
            @Override
            public String getClientId() {
                // The clientId can be any string.
                return "id";
            }
            @Override
            public Map<String, Object> getSignExtraData() {
                return null;
            }
            @Override
            public void onConnectResult(boolean isSuccess, ISubDeviceChannel iSubDeviceChannel, AError aError) {
                // Result of the add operation.
                if (isSuccess) {
                    // The sub-device is added. You can now proceed to log in the sub-device.
                    ALog.i(TAG, "Successfully added the topological relationship: " + JSONObject.toJSONString(iSubDeviceChannel));
                    //Log in the sub-device.
                    gatewaySubDeviceLogin();
                } else {
                    ALog.i(TAG, "Failed to add the topological relationship: " + JSONObject.toJSONString(aError));
                }
            }
            @Override
            public void onDataPush(String s, AMessage aMessage) {
            }
        });
    }
    public void  gatewayDeleteSubDevice(){
        BaseInfo baseInfo1 = new BaseInfo();
        baseInfo1.productKey = "a1j7S**************";
        baseInfo1.deviceName = "saf*********";
        LinkKit.getInstance().getGateway().gatewayDeleteSubDevice(baseInfo1, new ISubDeviceRemoveListener() {
            @Override
            public void onSuccess() {
                // The listener is called when the sub-device is successfully deleted. You can take the sub-device offline before deleting it.
            }
            @Override
            public void onFailed(AError aError) {
                // Failed to delete the sub-device.
            }
        });
    }
    /**
     * Before you call the API to log in the sub-device, make sure the topological relationship is established. After the gateway discovers a connected sub-device, it must notify IoT Platform that the sub-device is online.
     * After the sub-device is online, you can perform operations such as subscribing to topics and publishing messages.
     */
    public void gatewaySubDeviceLogin(){
        BaseInfo baseInfo1 = new BaseInfo();
        baseInfo1.productKey = "a1j7SyR***********";
        baseInfo1.deviceName = "safa*********";
        LinkKit.getInstance().getGateway().gatewaySubDeviceLogin(baseInfo1, new ISubDeviceActionListener() {
            @Override
            public void onSuccess() {
                // The sub-device is logged in by proxy.
                // After the sub-device is online, you can subscribe to topics, publish messages, and delete or disable the sub-device.
                // subDevDisable(null);
                // subDevDelete(null);
            }
            @Override
            public void onFailed(AError aError) {
                ALog.d(TAG, "onFailed() called with: aError = [" + aError + "]");
            }
        });
    }
}