| author | ms.author | ms.service | ms.topic | ms.date |
|---|---|---|---|---|
dominicbetts |
dobett |
iot-pnp |
include |
11/24/2020 |
To complete the steps in this article, you need the following:
- An Azure IoT Central application created using the Custom application template. For more information, see the create an application quickstart. The application must have been created on or after 14 July 2020.
- A development machine with Java SE Development Kit 8. In Java long-term support for Azure and Azure Stack, under Long-term support, select Java 8.
- Apache Maven 3.
- A local copy of the Microsoft Azure IoT SDK for Java GitHub repository that contains the sample code. Use this link to download a copy of the repository: Download ZIP. Then unzip the file to a suitable location on your local machine.
In the copy of the Microsoft Azure IoT SDK for Java you downloaded previously, open the azure-iot-sdk-java/device/iot-device-samples/pnp-device-sample/thermostat-device-sample/src/main/java/samples/com/microsoft/azure/sdk/iot/device/Thermostat.java file in a text editor.
When you run the sample to connect to IoT Central, it uses the Device Provisioning Service (DPS) to register the device and generate a connection string. The sample retrieves the DPS connection information it needs from the command-line environment.
The main method:
- Calls
initializeAndProvisionDeviceto set thedtmi:com:example:Thermostat;1model ID, use DPS to provision and register the device, create a DeviceClient instance, and connect to your IoT Central application. IoT Central uses the model ID to identify or generate the device template for this device. To learn more, see Associate a device with a device template. - Creates a command handler for the
getMaxMinReportcommand. - Creates a property update handler for the writable
targetTemperatureproperty. - Starts a thread to send temperature telemetry and update the
maxTempSinceLastRebootproperty every five seconds.
async function main() {
public static void main(String[] args) throws URISyntaxException, IOException, ProvisioningDeviceClientException, InterruptedException {
// ...
switch (deviceSecurityType.toLowerCase())
{
case "dps":
{
if (validateArgsForDpsFlow())
{
initializeAndProvisionDevice();
break;
}
throw new IllegalArgumentException("Required environment variables are not set for DPS flow, please recheck your environment.");
}
case "connectionstring":
{
// ...
}
default:
{
// ...
}
}
deviceClient.startDeviceTwin(new TwinIotHubEventCallback(), null, new TargetTemperatureUpdateCallback(), null);
Map<Property, Pair<TwinPropertyCallBack, Object>> desiredPropertyUpdateCallback =
Collections.singletonMap(
new Property("targetTemperature", null),
new Pair<>(new TargetTemperatureUpdateCallback(), null));
deviceClient.subscribeToTwinDesiredProperties(desiredPropertyUpdateCallback);
String methodName = "getMaxMinReport";
deviceClient.subscribeToDeviceMethod(new GetMaxMinReportMethodCallback(), methodName, new MethodIotHubEventCallback(), methodName);
new Thread(new Runnable() {
@SneakyThrows({InterruptedException.class, IOException.class})
@Override
public void run() {
while (true) {
if (temperatureReset) {
// Generate a random value between 5.0°C and 45.0°C for the current temperature reading.
temperature = BigDecimal.valueOf(random.nextDouble() * 40 + 5).setScale(1, RoundingMode.HALF_UP).doubleValue();
temperatureReset = false;
}
sendTemperatureReading();
Thread.sleep(5 * 1000);
}
}
}).start();
}The initializeAndProvisionDevice method shows how the device uses DPS to register and connect to IoT Central. The payload includes the model ID that IoT Central uses to associate the device with a device template.:
private static void initializeAndProvisionDevice() throws ProvisioningDeviceClientException, IOException, URISyntaxException, InterruptedException {
SecurityProviderSymmetricKey securityClientSymmetricKey = new SecurityProviderSymmetricKey(deviceSymmetricKey.getBytes(), registrationId);
ProvisioningDeviceClient provisioningDeviceClient = null;
ProvisioningStatus provisioningStatus = new ProvisioningStatus();
provisioningDeviceClient = ProvisioningDeviceClient.create(globalEndpoint, scopeId, provisioningProtocol, securityClientSymmetricKey);
AdditionalData additionalData = new AdditionalData();
additionalData.setProvisioningPayload(String.format("{\"modelId\": \"%s\"}", MODEL_ID));
provisioningDeviceClient.registerDevice(new ProvisioningDeviceClientRegistrationCallbackImpl(), provisioningStatus, additionalData);
while (provisioningStatus.provisioningDeviceClientRegistrationInfoClient.getProvisioningDeviceClientStatus() != ProvisioningDeviceClientStatus.PROVISIONING_DEVICE_STATUS_ASSIGNED)
{
if (provisioningStatus.provisioningDeviceClientRegistrationInfoClient.getProvisioningDeviceClientStatus() == ProvisioningDeviceClientStatus.PROVISIONING_DEVICE_STATUS_ERROR ||
provisioningStatus.provisioningDeviceClientRegistrationInfoClient.getProvisioningDeviceClientStatus() == ProvisioningDeviceClientStatus.PROVISIONING_DEVICE_STATUS_DISABLED ||
provisioningStatus.provisioningDeviceClientRegistrationInfoClient.getProvisioningDeviceClientStatus() == ProvisioningDeviceClientStatus.PROVISIONING_DEVICE_STATUS_FAILED)
{
provisioningStatus.exception.printStackTrace();
System.out.println("Registration error, bailing out");
break;
}
System.out.println("Waiting for Provisioning Service to register");
Thread.sleep(MAX_TIME_TO_WAIT_FOR_REGISTRATION);
}
ClientOptions options = new ClientOptions();
options.setModelId(MODEL_ID);
if (provisioningStatus.provisioningDeviceClientRegistrationInfoClient.getProvisioningDeviceClientStatus() == ProvisioningDeviceClientStatus.PROVISIONING_DEVICE_STATUS_ASSIGNED) {
// ...
String iotHubUri = provisioningStatus.provisioningDeviceClientRegistrationInfoClient.getIothubUri();
String deviceId = provisioningStatus.provisioningDeviceClientRegistrationInfoClient.getDeviceId();
deviceClient = DeviceClient.createFromSecurityProvider(iotHubUri, deviceId, securityClientSymmetricKey, IotHubClientProtocol.MQTT, options);
deviceClient.open();
}
}The sendTemperatureTelemetry method shows how the device sends the temperature telemetry to IoT Central:
private static void sendTemperatureTelemetry() {
String telemetryName = "temperature";
String telemetryPayload = String.format("{\"%s\": %f}", telemetryName, temperature);
Message message = new Message(telemetryPayload);
message.setContentEncoding(StandardCharsets.UTF_8.name());
message.setContentTypeFinal("application/json");
deviceClient.sendEventAsync(message, new MessageIotHubEventCallback(), message);
temperatureReadings.put(new Date(), temperature);
}The updateMaxTemperatureSinceLastReboot method sends a maxTempSinceLastReboot property update to IoT Central:
private static void updateMaxTemperatureSinceLastReboot() throws IOException {
String propertyName = "maxTempSinceLastReboot";
Property reportedProperty = new Property(propertyName, maxTemperature);
deviceClient.sendReportedProperties(Collections.singleton(reportedProperty));
}The TargetTemperatureUpdateCallback class contains the TwinPropertyCallBack method to handle writable property updates from IoT Central:
String propertyName = "targetTemperature";
public void TwinPropertyCallBack(Property property, Object context) {
if (property.getKey().equalsIgnoreCase(propertyName)) {
double targetTemperature = ((Number)property.getValue()).doubleValue();
EmbeddedPropertyUpdate pendingUpdate = new EmbeddedPropertyUpdate(targetTemperature, StatusCode.IN_PROGRESS.value, property.getVersion(), null);
Property reportedPropertyPending = new Property(propertyName, pendingUpdate);
try {
deviceClient.sendReportedProperties(Collections.singleton(reportedPropertyPending));
} catch (IOException e) {
throw new RuntimeException("IOException when sending reported property update: ", e);
}
// Update temperature in 2 steps
double step = (targetTemperature - temperature) / 2;
for (int i = 1; i <=2; i++) {
temperature = BigDecimal.valueOf(temperature + step).setScale(1, RoundingMode.HALF_UP).doubleValue();
Thread.sleep(5 * 1000);
}
EmbeddedPropertyUpdate completedUpdate = new EmbeddedPropertyUpdate(temperature, StatusCode.COMPLETED.value, property.getVersion(), "Successfully updated target temperature");
Property reportedPropertyCompleted = new Property(propertyName, completedUpdate);
deviceClient.sendReportedProperties(Collections.singleton(reportedPropertyCompleted));
} else {
log.debug("Property: Received an unrecognized property update from service.");
}
}The GetMaxMinReportMethodCallback class contains the call method to handle commands called from IoT Central:
String commandName = "getMaxMinReport";
public DeviceMethodData call(String methodName, Object methodData, Object context) {
if (methodName.equalsIgnoreCase(commandName)) {
String jsonRequest = new String((byte[]) methodData, StandardCharsets.UTF_8);
Date since = getCommandRequestValue(jsonRequest, Date.class);
double runningTotal = 0;
Map<Date, Double> filteredReadings = new HashMap<>();
for (Map.Entry<Date, Double> entry : temperatureReadings.entrySet()) {
if (entry.getKey().after(since)) {
filteredReadings.put(entry.getKey(), entry.getValue());
runningTotal += entry.getValue();
}
}
if (filteredReadings.size() > 1) {
SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd'T'HH:mm:ss'Z'");
double maxTemp = Collections.max(filteredReadings.values());
double minTemp = Collections.min(filteredReadings.values());
double avgTemp = runningTotal / filteredReadings.size();
String startTime = sdf.format(Collections.min(filteredReadings.keySet()));
String endTime = sdf.format(Collections.max(filteredReadings.keySet()));
String responsePayload = String.format(
"{\"maxTemp\": %.1f, \"minTemp\": %.1f, \"avgTemp\": %.1f, \"startTime\": \"%s\", \"endTime\": \"%s\"}",
maxTemp,
minTemp,
avgTemp,
startTime,
endTime);
return new DeviceMethodData(StatusCode.COMPLETED.value, responsePayload);
}
return new DeviceMethodData(StatusCode.NOT_FOUND.value, null);
}
log.error("Command: Unknown command {} invoked from service.", methodName);
return new DeviceMethodData(StatusCode.NOT_FOUND.value, null);
}[!INCLUDE iot-central-connection-configuration]
On Windows, navigate to the root folder of the Java SDK repository you downloaded.
Run the following command to build the sample application:
mvn install -T 2C -DskipTests
To run the sample application, open a command-line environment and navigate to the folder azure-iot-sdk-java/device/iot-device-samples/pnp-device-sample/thermostat-device-sample folder that contains the Thermostat.java sample file.
[!INCLUDE iot-central-connection-environment]
Run the sample:
mvn exec:java -Dexec.mainClass="samples.com.microsoft.azure.sdk.iot.device.Thermostat"
The following output shows the device registering and connecting to IoT Central. The sample starts sending telemetry:
Waiting for Provisioning Service to register
Waiting for Provisioning Service to register
IotHUb Uri : iotc-...azure-devices.net
Device ID : sample-device-01
2020-11-05 14:38:27.218 DEBUG Thermostat:208 - Opening the device client.
2020-11-05 14:38:27.253 DEBUG MqttIotHubConnection:122 - Opening MQTT connection...
2020-11-05 14:38:27.405 DEBUG Mqtt:117 - Sending MQTT CONNECT packet...
2020-11-05 14:38:28.782 DEBUG Mqtt:121 - Sent MQTT CONNECT packet was acknowledged
2020-11-05 14:38:28.786 DEBUG Mqtt:291 - Sending MQTT SUBSCRIBE packet for topic devices/sample-device-01/messages/devicebound/#
2020-11-05 14:38:28.965 DEBUG Mqtt:297 - Sent MQTT SUBSCRIBE packet for topic devices/sample-device-01/messages/devicebound/# was acknowledged
2020-11-05 14:38:28.967 DEBUG MqttIotHubConnection:205 - MQTT connection opened successfully
2020-11-05 14:38:28.968 INFO IotHubTransport:270 - The connection to the IoT Hub has been established
2020-11-05 14:38:28.970 INFO IotHubTransport:1133 - Updating transport status to new status CONNECTED with reason CONNECTION_OK
2020-11-05 14:38:28.972 DEBUG IotHubTransport:1143 - Invoking connection status callbacks with new status details
2020-11-05 14:38:28.976 INFO IotHubTransport:327 - Client connection opened successfully
2020-11-05 14:38:28.978 INFO DeviceClient:398 - Device client opened successfully
2020-11-05 14:38:28.979 DEBUG Thermostat:142 - Start twin and set handler to receive "targetTemperature" updates.
2020-11-05 14:38:28.993 INFO IotHubTransport:421 - Message was queued to be sent later ( Message details: Correlation Id [85f8f25b-924e-47a1-b7f0-e7bd227cbb9f] Message Id [df65a02b-6d75-40fe-8636-a571ad3ae970] Device Operation Type [DEVICE_OPERATION_TWIN_SUBSCRIBE_DESIRED_PROPERTIES_REQUEST] )
2020-11-05 14:38:28.994 INFO IotHubTransport:1040 - Sending message ( Message details: Correlation Id [85f8f25b-924e-47a1-b7f0-e7bd227cbb9f] Message Id [df65a02b-6d75-40fe-8636-a571ad3ae970] Device Operation Type [DEVICE_OPERATION_TWIN_SUBSCRIBE_DESIRED_PROPERTIES_REQUEST] )
2020-11-05 14:38:29.000 INFO IotHubTransport:421 - Message was queued to be sent later ( Message details: Correlation Id [d3692283-63d6-446a-aeab-5a4e4aa9e948] Message Id [d53139e3-acb4-458b-8c03-119d8fc04d5a] Request Id [0] Device Operation Type [DEVICE_OPERATION_TWIN_GET_REQUEST] )
2020-11-05 14:38:29.018 DEBUG Mqtt:291 - Sending MQTT SUBSCRIBE packet for topic $iothub/twin/res/#
2020-11-05 14:38:29.080 INFO IotHubTransport:421 - Message was queued to be sent later ( Message details: Correlation Id [f8c2180d-7289-4bf8-afa5-0ad6565a27eb] Message Id [c553e8bd-3c7e-4830-a3e7-12964cf3d936] Device Operation Type [DEVICE_OPERATION_TWIN_SUBSCRIBE_DESIRED_PROPERTIES_REQUEST] )
2020-11-05 14:38:29.103 DEBUG Thermostat:150 - Set handler to receive "getMaxMinReport" command.
2020-11-05 14:38:29.127 INFO IotHubTransport:421 - Message was queued to be sent later ( Message details: Correlation Id [c6f3c2e6-68da-4d52-b429-9e62418a2fd7] Message Id [7f17f191-7ab0-46e7-897e-a635c0519287] Device Operation Type [DEVICE_OPERATION_METHOD_SUBSCRIBE_REQUEST] )
2020-11-05 14:38:29.167 INFO IotHubTransport:421 - Message was queued to be sent later ( Message details: Correlation Id [e1dc7b20-1783-462a-87db-a63042a583c4] Message Id [752f3b01-6c28-4f76-a314-97c75f37bc64] )
2020-11-05 14:38:29.169 DEBUG Thermostat:419 - Telemetry: Sent - {"temperature": 39.6 C} with message Id 752f3b01-6c28-4f76-a314-97c75f37bc64.
[!INCLUDE iot-central-monitor-thermostat]
You can see how the device responds to commands and property updates:
2020-11-05 14:43:03.179 DEBUG Thermostat:318 - Command: Received - Generating min, max, avg temperature report since Thu Nov 05 06:30:00 GMT 2020.
2020-11-05 14:43:03.180 DEBUG Thermostat:345 - Command: MaxMinReport since Thu Nov 05 06:30:00 GMT 2020: "maxTemp": 33.1 C, "minTemp": 33.1 C, "avgTemp": 33.1 C, "startTime": 2020-11-05T14:42:28Z, "endTime": 2020-11-05T14:42:58Z
...
2020-11-05 14:49:08.182 DEBUG Thermostat:261 - Property: Received - {"targetTemperature": 56.0 C}.
2020-11-05 14:49:08.185 DEBUG Thermostat:270 - Property: Update - {"targetTemperature": 56.0 C} is IN_PROGRESS
2020-11-05 14:49:18.206 DEBUG Thermostat:282 - Property: Update - {"targetTemperature": 55.9 C} is COMPLETED