Invio di dati da un dispositivo associato

Inviare dati per conto di un dispositivo associato.

Esempio di codice

Go

Per maggiori informazioni, consulta la documentazione di riferimento per le API Cloud IoT Core Go.

Per eseguire l'autenticazione in Cloud IoT Core, configura le Credenziali predefinite dell'applicazione. Per saperne di più, consulta Configurare l'autenticazione per un ambiente di sviluppo locale.

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import (
	"errors"
	"fmt"
	"io"
	"math/rand"
	"time"

	mqtt "github.com/eclipse/paho.mqtt.golang"
)

// sendDataFromBoundDevice starts a gateway client that sends data on behalf of a bound device.
func sendDataFromBoundDevice(w io.Writer, projectID string, region string, registryID string, gatewayID string, deviceID string, privateKeyPath string, algorithm string, numMessages int, payload string) error {
	const (
		mqttBrokerURL      = "tls://mqtt.googleapis.com:8883"
		protocolVersion    = 4  // corresponds to MQTT 3.1.1
		minimumBackoffTime = 1  // initial backoff time in seconds
		maximumBackoffTime = 32 // maximum backoff time in seconds
	)

	var backoffTime = minimumBackoffTime
	var shouldBackoff = false

	// onConnect defines the on connect handler which resets backoff variables.
	var onConnect mqtt.OnConnectHandler = func(client mqtt.Client) {
		fmt.Fprintf(w, "Client connected: %t\n", client.IsConnected())

		shouldBackoff = false
		backoffTime = minimumBackoffTime
	}

	// onMessage defines the message handler for the mqtt client.
	var onMessage mqtt.MessageHandler = func(client mqtt.Client, msg mqtt.Message) {
		fmt.Fprintf(w, "Topic: %s\n", msg.Topic())
		fmt.Fprintf(w, "Message: %s\n", msg.Payload())
	}

	// onDisconnect defines the connection lost handler for the mqtt client.
	var onDisconnect mqtt.ConnectionLostHandler = func(client mqtt.Client, err error) {
		fmt.Fprintln(w, "Client disconnected")
		shouldBackoff = true
	}

	jwt, _ := createJWT(projectID, privateKeyPath, algorithm, 60)
	clientID := fmt.Sprintf("projects/%s/locations/%s/registries/%s/devices/%s", projectID, region, registryID, gatewayID)

	opts := mqtt.NewClientOptions()
	opts.AddBroker(mqttBrokerURL)
	opts.SetClientID(clientID)
	opts.SetUsername("unused")
	opts.SetPassword(jwt)
	opts.SetProtocolVersion(protocolVersion)
	opts.SetOnConnectHandler(onConnect)
	opts.SetDefaultPublishHandler(onMessage)
	opts.SetConnectionLostHandler(onDisconnect)

	// Create and connect a client using the above options.
	client := mqtt.NewClient(opts)
	if token := client.Connect(); token.Wait() && token.Error() != nil {
		fmt.Fprintln(w, "Failed to connect client")
		return token.Error()
	}

	if err := attachDevice(deviceID, client, ""); err != nil {
		fmt.Fprintf(w, "Failed to attach device %s\n", err)
		return err
	}

	// Sleep for 5 seconds to allow attachDevice message to propagate.
	time.Sleep(5 * time.Second)

	gatewayStateTopic := fmt.Sprintf("/devices/%s/state", gatewayID)
	deviceStateTopic := fmt.Sprintf("/devices/%s/state", deviceID)

	gatewayInitPayload := fmt.Sprintf("Starting gateway at time: %d", time.Now().Unix())
	if token := client.Publish(gatewayStateTopic, 1, false, gatewayInitPayload); token.Wait() && token.Error() != nil {
		fmt.Fprintln(w, "Failed to publish initial gateway payload")
		return token.Error()
	}

	for i := 1; i <= numMessages; i++ {
		if shouldBackoff {
			if backoffTime > maximumBackoffTime {
				fmt.Fprintln(w, "Exceeded max backoff time.")
				return errors.New("exceeded maximum backoff time, exiting")
			}

			waitTime := backoffTime + rand.Intn(1000)/1000.0
			time.Sleep(time.Duration(waitTime) * time.Second)

			backoffTime *= 2
			client = mqtt.NewClient(opts)
		}

		deviceStatePayload := fmt.Sprintf("%s, #%d", payload, i)

		fmt.Fprintf(w, "Publishing message: %s to %s\n", deviceStatePayload, deviceStateTopic)

		if token := client.Publish(deviceStateTopic, 1, false, payload); token.Wait() && token.Error() != nil {
			fmt.Fprintln(w, "Failed to publish payload to device state topic")
			return token.Error()
		}

		// Sleep for a bit between messages to simulate real world device state publishing.
		time.Sleep(5 * time.Second)
	}

	detachDevice(deviceID, client, "")

	client.Disconnect(20)
	return nil
}

Node.js

Per maggiori informazioni, consulta la documentazione di riferimento per le API Cloud IoT Core Node.js.

Per eseguire l'autenticazione in Cloud IoT Core, configura le Credenziali predefinite dell'applicazione. Per saperne di più, consulta Configurare l'autenticazione per un ambiente di sviluppo locale.

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// const deviceId = `myDevice`;
// const gatewayId = `mygateway`;
// const registryId = `myRegistry`;
// const region = `us-central1`;
// const algorithm = `RS256`;
// const privateKeyFile = `./rsa_private.pem`;
// const serverCertFile = `./roots.pem`;
// const mqttBridgeHostname = `mqtt.googleapis.com`;
// const mqttBridgePort = 8883;
// const numMessages = 5;
// const tokenExpMins = 60;

const mqttClientId = `projects/${projectId}/locations/${region}/registries/${registryId}/devices/${gatewayId}`;
console.log(`MQTT client id: ${mqttClientId}`);
const connectionArgs = {
  host: mqttBridgeHostname,
  port: mqttBridgePort,
  clientId: mqttClientId,
  username: 'unused',
  password: createJwt(projectId, privateKeyFile, algorithm),
  protocol: 'mqtts',
  qos: 1,
  secureProtocol: 'TLSv1_2_method',
  ca: [readFileSync(serverCertFile)],
};

// Create a client, and connect to the Google MQTT bridge.
const iatTime = parseInt(Date.now() / 1000);
const client = mqtt.connect(connectionArgs);

client.on('connect', success => {
  if (!success) {
    console.log('Client not connected...');
  } else if (!publishChainInProgress) {
    console.log('Client connected: Attaching device');
    attachDevice(deviceId, client);
    setTimeout(() => {
      console.log('Client connected: Gateway is ready to relay');
      publishAsyncGateway(
        client,
        iatTime,
        tokenExpMins,
        0,
        numMessages,
        registryId,
        deviceId,
        gatewayId,
        connectionArgs,
        projectId,
        privateKeyFile,
        algorithm
      );
    }, 5000);
  }
});

client.on('close', () => {
  console.log('Connection closed');
  shouldBackoff = true;
});

client.on('error', err => {
  console.log('error', err);
});

client.on('message', (topic, message) => {
  console.log(
    'message received: ',
    Buffer.from(message, 'base64').toString('ascii')
  );
});

client.on('packetsend', () => {
  // Note: logging packet send is very verbose
});

Passaggi successivi

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