IoT Platform:Exemplo de conexão do SDK em Go

import "pack.ag/amqp"

package main
import (
	"os"
    "context"
    "crypto/hmac"
    "crypto/sha1"
    "encoding/base64"
    "fmt"
    "pack.ag/amqp"
    "time"
)
// For parameter descriptions, see the AMQP client connection guide.
const consumerGroupId = "${YourConsumerGroupId}"
const clientId = "${YourClientId}"
// iotInstanceId: The instance ID.
const iotInstanceId = "${YourIotInstanceId}"
// The endpoint. For more information, see the AMQP client connection guide.
const host = "${YourHost}"
func main() {
	// If you leak the project code, your AccessKey may be exposed. This compromises the security of all resources in your account. 
	// The following code provides an example on how to use an environment variable to obtain the AccessKey. This method is for reference only.
	accessKey := os.Getenv("ALIBABA_CLOUD_ACCESS_KEY_ID")
	accessSecret := os.Getenv("ALIBABA_CLOUD_ACCESS_KEY_SECRET")
    address := "amqps://" + host + ":5671"
    timestamp := time.Now().Nanosecond() / 1000000
    // For information about how to construct the user name, see the AMQP client connection guide.
    userName := fmt.Sprintf("%s|authMode=aksign,signMethod=Hmacsha1,consumerGroupId=%s,authId=%s,iotInstanceId=%s,timestamp=%d|", 
        clientId, consumerGroupId, accessKey, iotInstanceId, timestamp)
    stringToSign := fmt.Sprintf("authId=%s&timestamp=%d", accessKey, timestamp)
    hmacKey := hmac.New(sha1.New, []byte(accessSecret))
    hmacKey.Write([]byte(stringToSign))
    // Calculate the signature. For information about how to construct the password, see the AMQP client connection guide.
    password := base64.StdEncoding.EncodeToString(hmacKey.Sum(nil))
    amqpManager := &AmqpManager{
        address:address,
        userName:userName,
        password:password,
    }
    // To accept messages or cancel operations, derive the context from context.Background().
    ctx := context.Background()
    amqpManager.startReceiveMessage(ctx)
}
// Business function. This is a custom implementation. The function is executed asynchronously. Consider the resource consumption of your system.
func (am *AmqpManager) processMessage(message *amqp.Message) {
    fmt.Println("data received:", string(message.GetData()), " properties:", message.ApplicationProperties)
}
type AmqpManager struct {
    address     string
    userName     string
    password     string
    client       *amqp.Client
    session     *amqp.Session
    receiver     *amqp.Receiver
}
func (am *AmqpManager) startReceiveMessage(ctx context.Context)  {
    childCtx, _ := context.WithCancel(ctx)
    err := am.generateReceiverWithRetry(childCtx)
    if nil != err {
        return
    }
    defer func() {
        am.receiver.Close(childCtx)
        am.session.Close(childCtx)
        am.client.Close()
    }()
    for {
        // Blocks to receive messages. If the context is background, the process is not interrupted.
        message, err := am.receiver.Receive(ctx)
        if nil == err {
            go am.processMessage(message)
            message.Accept()
        } else {
            fmt.Println("amqp receive data error:", err)
            // If the operation is actively canceled, exit the program.
            select {
            case <- childCtx.Done(): return
            default:
            }
            // If the operation is not actively canceled, re-establish the connection.
            err := am.generateReceiverWithRetry(childCtx)
            if nil != err {
                return
            }
        }
    }
}
func (am *AmqpManager) generateReceiverWithRetry(ctx context.Context) error {
    // Back off and reconnect. Start with 10 ms and double the interval up to 20s.
    duration := 10 * time.Millisecond
    maxDuration := 20000 * time.Millisecond
    times := 1
    // In case of an exception, back off and reconnect.
    for {
        select {
        case <- ctx.Done(): return amqp.ErrConnClosed
        default:
        }
        err := am.generateReceiver()
        if nil != err {
            time.Sleep(duration)
            if duration < maxDuration {
                duration *= 2
            }
            fmt.Println("amqp connect retry,times:", times, ",duration:", duration)
            times ++
        } else {
            fmt.Println("amqp connect init success")
            return nil
        }
    }
}
// The connection and session states cannot be determined because the package is not visible. Restart the connection to retrieve the states.
func (am *AmqpManager) generateReceiver() error {
    if am.session != nil {
        receiver, err := am.session.NewReceiver(
            amqp.LinkSourceAddress("/queue-name"),
            amqp.LinkCredit(20),
        )
        // If a network disconnection occurs, the connection closes and session creation fails. 
        // If the connection remains open, the session is created successfully.
        if err == nil {
            am.receiver = receiver
            return nil
        }
    }
    // Clean up the previous connection.
    if am.client != nil {
        am.client.Close()
    }
    client, err := amqp.Dial(am.address, amqp.ConnSASLPlain(am.userName, am.password), )
    if err != nil {
        return err
    }
    am.client = client
    session, err := client.NewSession()
    if err != nil {
        return err
    }
    am.session = session
    receiver, err := am.session.NewReceiver(
        amqp.LinkSourceAddress("/queue-name"),
        amqp.LinkCredit(20),
    )
    if err != nil {
        return err
    }
    am.receiver = receiver
    return nil
}