This document describes how to create a device in the IoT Explorer console and quickly try out how it connects to Tencent Cloud over MQTT and disconnects from MQTT with the aid of the demo.
Before connecting devices to the SDK, you need to create project products and devices in the console and get the product ID, device name, device certificate (for certificate authentication), device private key (for certificate authentication), and device key (for key authentication), which are required for authentication of the devices when you connect them to the cloud. For more information, please see Project Management, Product Definition, and Device Debugging.
Download the sample code of IoT Explorer SDK for Java demo.
Edit the parameter configuration information in the unit_test_config.json file in the demo.
{
"TESTMQTTSAMPLE_PRODUCT_ID": "",
"TESTMQTTSAMPLE_DEVICE_NAME": "",
"TESTMQTTSAMPLE_DEVICE_PSK": "",
}
If key authentication is used during device creation in the console, you need to enter TESTMQTTSAMPLE_PRODUCT_ID (product ID), TESTMQTTSAMPLE_DEVICE_NAME (device name), and TESTMQTTSAMPLE_DEVICE_PSK (device key) in unit_test_config.json. Key authentication is used in the demo.
Place the certificate and private key in the resources folder.
If certificate authentication is used during device creation in the console, in addition to entering the TESTMQTTSAMPLE_PRODUCT_ID (product ID) and TESTMQTTSAMPLE_DEVICE_NAME (device name) in unit_test_config.json.json, you also need to enter mDevCert(DEVICE_CERT_FILE_NAME) (device certificate file name) and mDevPriv(DEVICE_PRIVATE_KEY_FILE_NAME) (device private key file name) in MqttSampleTest.java.
You can set the data template for each product created in the console. The features of the data template are divided into three categories: attribute, event, and action. For more information on how to use a data template in the console, please see Data Template.
For the devices in the demo, you need to import the JSON files downloaded from the console into the demo to standardize the data verification during attribute and event reporting. Please place the JSON file in the resources folder and set the mJsonFileName (JSON file name) in MqttSampleTest.java for the gateway device.
Run the testMqttConnect function in MqttSampleTest.java and call connect() in testMqttConnect. Below is the sample code:
private static void connect() {
// init connection
mDataTemplateSample = new DataTemplateSample(mBrokerURL, mProductID, mDevName, mDevPSK, mDevCert, mDevPriv, new SelfMqttActionCallBack(), mJsonFileName, new SelfDownStreamCallBack());
mDataTemplateSample.connect();
}
Observe the logcat log.
23/02/2021 19:15:30,410 [MQTT Call: LWVUL5SZ2Llight1] INFO MqttSampleTest onConnectCompleted 288 - onConnectCompleted, status[OK], reconnect[false], userContext[MQTTRequest{requestType='connect', requestId=0}], msg[connected to ssl://LWVUL5SZ2L.iotcloud.tencentdevices.com:8883]
The above log represents the process in which the device is connected to the cloud over MQTT successfully. In the console, you can see that the status of the device has been updated to online.
TXMqttActionCallBack is the callback for device action.
/**
* Callback for MQTT connection completion
*
* @param status Status.OK: connection succeeded; Status.ERROR: connection failed
* @param reconnect true: reconnection false: first connection
* @param userContext User context
* @param msg Connection information
*/
@Override
public void onConnectCompleted(Status status, boolean reconnect, Object userContext, String msg){}
/**
* Callback for MQTT disconnection
*
* @param cause Disconnection cause
*/
@Override
public void onConnectionLost(Throwable cause) {}
/**
* Callback for MQTT disconnection completion
*
* @param status Status.OK: disconnection succeeded; Status.ERROR: disconnection failed
* @param userContext User context
* @param msg Details
*/
@Override
public void onDisconnectCompleted(Status status, Object userContext, String msg) {}
/**
* Callback for message publishing completion
*
* @param status Status.OK: message publishing succeeded; Status.ERROR: message publishing failed
* @param token Message token, containing the message content structure
* @param userContext User context
* @param msg Details
*/
@Override
public void onPublishCompleted(Status status, IMqttToken token, Object userContext, String errMsg) {}
/**
* Callback for topic subscription completion
*
* @param status Status.OK: subscription succeeded; Status.ERROR: subscription failed
* @param token Message token, containing the message content structure
* @param userContext User context
* @param msg Details
*/
@Override
public void onSubscribeCompleted(Status status, IMqttToken asyncActionToken, Object userContext, String errMsg) {}
/**
* Callback for topic unsubscription completion
*
* @param status Status.OK: unsubscription succeeded; Status.ERROR: unsubscription failed
* @param token Message token, containing the message content structure
* @param userContext User context
* @param msg Details
*/
@Override
public void onUnSubscribeCompleted(Status status, IMqttToken asyncActionToken, Object userContext, String errMsg) {}
/**
* Push for the message received from the subscribed topic
*
* @param topic Topic name
* @param message Message content
*/
@Override
public void onMessageReceived(final String topic, final MqttMessage message) {}
TXDataTemplateDownStreamCallBack is the callback for downstream message processing. The prerequisite for receiving the following callbacks is for the device to subscribe to the relevant data template topics after it is connected. For more information, please see Subscribing to and Unsubscribing from Topic.
/**
* Reply callbacks for attribute reporting, device information reporting, control clearing, event reporting, and multi-event reporting
*
* @param replyMsg Reply information for attribute reporting, device information reporting, control clearing, event reporting, and multi-event reporting
*/
@Override
public void onReplyCallBack(String replyMsg) {}
/**
* Callback for reply to device-reported latest information acquisition
*
* @param data Reply information for device-reported latest information acquisition
*/
@Override
public void onGetStatusReplyCallBack(JSONObject data) {}
/**
* Callback for the control information received for attribute delivery from the cloud
*
* @param msg Control information received for attribute delivery from the cloud
* @return `JSONObject` containing `code` (reply code) and `status` (reply information), which is used to reply to the attribute delivery control message
*/
@Override
public JSONObject onControlCallBack(JSONObject msg) {}
/**
* Callback for the received action information delivered by the cloud to the device
*
* @param msg Received action information delivered by the cloud to the device
* @return `JSONObject` containing `code` (reply code) and `status` (reply information), which is used to reply to the delivered action message
*/
@Override
public JSONObject onActionCallBack(String actionId, JSONObject params){}
/**
* The notification message sent to the device by the cloud when the user deletes the device on the Tencent IoT Link mini program or application, which is used to reset the device or used by a gateway device to clear the subdevice data
*
* @param msg The notification message sent to the device by the cloud when the user deletes the device on the Tencent IoT Link mini program or application
*/
@Override
public void onUnbindDeviceCallBack(String msg) {}
/**
* The notification message sent to the device by the cloud when the user binds the device on the Tencent IoT Link mini program or application, which can be processed based on the business needs after being received by the device
*
* @param msg The notification message sent to the device by the cloud when the user binds the device on the Tencent IoT Link mini program or application
*/
@Override
public void onBindDeviceCallBack(String msg) {}
getConnectStatus()API can be used to get the device connection status.
enum ConnectStatus {
kConnectIdle, // Initial status
kConnecting, // Connecting
kConnected, // Connected
kConnectFailed,// Connection failed
kDisconnected // Disconnected
}
Run the testMqttConnect function in MqttSampleTest.java and call disconnect() after connect() calls back onConnectCompleted. Below is the sample code:
private static void disconnect() {
mDataTemplateSample.disconnect();
}
Observe the logcat log.
23/02/2021 19:31:24,315 [MQTT Disc: LWVUL5SZ2Llight1] INFO MqttSampleTest onDisconnectCompleted 305 - onDisconnectCompleted, status[OK], userContext[MQTTRequest{requestType='disconnect', requestId=1}], msg[disconnected to ssl://LWVUL5SZ2L.iotcloud.tencentdevices.com:8883]
The above log represents the process in which the device disconnects from MQTT successfully. In the console, you can see that the status of the device has been updated to offline.