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Using Go, Python or Node.js with Topics and Events

Reviewed on 18 October 2024 • Published on 04 January 2023

AWS provides a number of Software Development Kits (SDKs) which provide language-specific APIs for AWS services, including SNS, which is the protocol that Scaleway Topics and Events is based on.

  • AWS provides a dedicated SDK for Go.
  • The AWS SDK for Python is Boto3.
  • For Node.js, use the AWS SDK for JavaScript, which can be installed from NPM.

This page provides code samples to show you how to get started using these SDKs with Scaleway Topics and Events.

Before you startLink to this anchor

To complete the actions presented below, you must have:

  • A Scaleway account logged into the console
  • Owner status or IAM permissions allowing you to perform actions in the intended Organization
  • Valid credentials for Topics and Events
  • Installed the relevant AWS SDK for Go, Python and/or JavaScript

GoLink to this anchor

Connect to Topics and Events (Go)Link to this anchor

The following code shows you how to connect to Scaleway Topics and Events:

import (
  "github.com/aws/aws-sdk-go/aws"
  "github.com/aws/aws-sdk-go/aws/credentials"
  "github.com/aws/aws-sdk-go/aws/session"
  "github.com/aws/aws-sdk-go/service/sns"
)
func main() {
  awsSession := session.Must(session.NewSession(&aws.Config{
    Region:   aws.String("fr-par"),
    Endpoint: aws.String("http://sns.mnq.fr-par.scaleway.com"),
    Credentials: credentials.NewStaticCredentials(AwsAccessKey, AwsSecretKey, ""),
  }))
  awsSns := sns.New(awsSession)
  [...]
}
Note

The Endpoint for Scaleway Topics and Events is https://sns.mnq.fr-par.scaleway.com. The values for the access and secret keys should be the credentials you generated for Topics and Events.

Once connected, you can use any of the SDK’s available functions. Be aware though that some functions are not supported by Scaleway Topics and Events, so make sure to check the link for more details on these. See the official SDK documentation for more information on getting started with the SDK, or keep reading for some code examples.

Create topic (Go)Link to this anchor

createTopicResponse, _ := awsSNS.CreateTopic(&sns.CreateTopicInput{
  Name: aws.String("my-test-topic"),
})
fmt.Println(*createTopicResponse.TopicArn)

Publish messages to this topic (Go)Link to this anchor

Be careful: messages sent to topics with no subscriptions are automatically deleted

for i := 0; i < 10; i++ {
  _, _ = awsSNS.Publish(&sns.PublishInput{
    Message:  aws.String(fmt.Sprintf("Hello World: %d", i)),
    TopicArn: createTopicResponse.TopicArn,
  })
}

Create subscriptions to this topic (Go)Link to this anchor

Subscribe to a public Scaleway function

This code triggers the function each time a message is published to the topic.

You can find the value for [Function URL] in the Scaleway console in the Endpoints tab of your function’s Overview page.

_, _ = awsSns.Subscribe(&sns.SubscribeInput{
  Endpoint: aws.String(FunctionUrl),
  Protocol: aws.String("lambda"),
  TopicArn: createTopicResponse.TopicArn,
})
#### Subscribe to an HTTP/S endpoint
```go
_, _ = awsSns.Subscribe(&sns.SubscribeInput{
  Endpoint: aws.String(Url),
  Protocol: aws.String("http"), // or https
  TopicArn: createTopicResponse.TopicArn,
})

The HTTP server should receive an HTTP request with a body in json matching the following format:

{
"Type": "SubscriptionConfirmation",
"Token": "<REDACTED-CONFIRMATION-TOKEN>",
"MessageId": "<REDACTED-MESSAGE-ID>",
"TopicArn": "arn:scw:sns:fr-par:<REDACTED-ID>:MyTopic",
"Message": "You have chosen to subscribe to the topic arn:scw:sns:fr-par:<REDACTED-ID>:MyTopic.\nTo confirm the subscription, visit the SubscribeURL included in this message.",
"Timestamp": "2022-06-29T10:03:34Z",
"SignatureVersion": "1",
"Signature": "<REDACTED-SIGNATURE>",
"SigningCertURL": "https://messaging.s3.fr-par.scw.cloud/fr-par/sns/sns_certificate_[certSerialNumber].crt",
"SubscribeURL": "<THE-CONFIRMATION-LINK>" // Get the confirmation link located here
}

The signing certificate of the message is in the JSON of the SigningCertURL. This certificate is also signed by the trust chain certificate (common name sns.mnq.srr.scw.cloud). For more information about verifying the authenticity of the message, refer to the official AWS documentation.

To confirm the subscription, make a request to the SubscribeURL using your browser or curl.

Delete all subscriptions (Go)Link to this anchor

listSubscriptions, _ := awsSns.ListSubscriptionsByTopic(&sns.ListSubscriptionsByTopicInput{
  TopicArn: createTopicResponse.TopicArn,
})
for _, sub := range listSubscriptions.Subscriptions {
  awsSns.Unsubscribe(&sns.UnsubscribeInput{
    SubscriptionArn: sub.SubscriptionArn,
  })
}

PythonLink to this anchor

Connect to Topics and Events (Python)Link to this anchor

The following code shows you how to connect to Topics and Events using Boto3’s resource(). You could also use client(), but we favor resource() as it is more pythonesque:

sns = boto3.resource('sns',
  endpoint_url=[],
  aws_access_key_id=[],
  aws_secret_access_key=[],
  region_name='fr-par')
Note

The endpoint_url for Scaleway Topics and Events (based on SNS) is https://sns.mnq.fr-par.scaleway.com. The values for the access and secret keys should be the credentials you generated for Topics and Events.

Once connected to, you can use any of the SDK’s available functions. However, some functions are not supported by Scaleway Topics and Events, so do check the link to make sure. See the official SDK documentation for more information, or keep reading for some code examples.

Create topic (Python)Link to this anchor

# Create a topic. This returns an SNS.Topic instance
topic = sns.create_topic(Name='test')  # You can now access identifiers and attributes
print(topic.arn)
print(topic.attributes)

Publish messages to this topic (Python)Link to this anchor

Be careful: messages sent to topics with no subscriptions are automatically deleted

for i in range (0,10):
  topic.publish(Message="Hello World: "+str(i))

Create subscriptions to this topic (Python)Link to this anchor

Subscribe to a public Scaleway function

This code triggers the function each time a message is published to the topic.

You can find the value for [Function URL] in the Scaleway console in the Endpoints tab of your function’s Overview page.

subscription_functions = topic.subscribe(
    Protocol='lambda',
    Endpoint=[Function URL],
    ReturnSubscriptionArn=True
)
subscription_functions = topic.subscribe(
    Protocol='lambda',
    Endpoint=[Function URL],
    ReturnSubscriptionArn=True,
    Attributes={
      'RedrivePolicy': '{"deadLetterTargetArn": "[Queue ARN]"}'
    }
)

Subscribe to an HTTP/S endpoint

subscription = topic.subscribe(
    Protocol='http', //or https
    Endpoint=url,
    ReturnSubscriptionArn=True
)

The HTTP server should receive an HTTP request with a body in json matching the following format:

{
"Type": "SubscriptionConfirmation",
"Token": "<REDACTED-CONFIRMATION-TOKEN>",
"MessageId": "<REDACTED-MESSAGE-ID>",
"TopicArn": "arn:scw:sns:fr-par:<REDACTED-ID>:MyTopic",
"Message": "You have chosen to subscribe to the topic arn:scw:sns:fr-par:<REDACTED-ID>:MyTopic.\nTo confirm the subscription, visit the SubscribeURL included in this message.",
"Timestamp": "2022-06-29T10:03:34Z",
"SignatureVersion": "1",
"Signature": "<REDACTED-SIGNATURE>",
"SigningCertURL": "http://<REDACTED-URL>/SNStest.crt",
"SubscribeURL": "<THE-CONFIRMATION-LINK>" // Get the confirmation link located here
}

To confirm the subscription, make a request to the SubscribeURL using your browser or curl.

Delete all subscriptions (Python)Link to this anchor

for subs in topic.subscriptions.all():
    subs.delete()

Node.jsLink to this anchor

Connect to Topics and Events (NodeJS)Link to this anchor

The following code sample shows how to connect to Topics and Events:

import { 
    CreateTopicCommand,
    DeleteTopicCommand,
    ListSubscriptionsByTopicCommand,
    ListTopicsCommand,
    PublishCommand,
    SNSClient,
    SubscribeCommand,
    UnsubscribeCommand,
 } from "@aws-sdk/client-sns";
var snsClient = new SNSClient({
    credentials : {
        accessKeyId : "",
        secretAccessKey: ""
    },
    region: "par",
    endpoint: "https://sns.mnq.fr-par.scaleway.com",
    
})
Note

The endpoint_url for Scaleway Topics and Events is https://sns.mnq.fr-par.scaleway.com. For the access and secret key values, use the credentials you generated for Topics and Events.

Once connected, you can use any of the SDK’s available functions. However, some functions are not supported by Scaleway Topics and Events, so do check the link to make sure. See the official SDK documentation for more information, or keep reading for some code examples.

Create topic (NodeJS)Link to this anchor

You can find all available parameters for createTopic in the AWS documentation.

var paramsTopic = {
    Name: 'MyTopic'
  };
const commandCreateTopic = new CreateTopicCommand(paramsTopic);
const restCreateTopic = await snsClient.send(commandCreateTopic);
const topicARN= restCreateTopic.TopicArn;
console.log(topicARN);

Publish messages to this topic (NodeJS)Link to this anchor

Be careful: messages sent to topics with no subscriptions are automatically deleted.

This code sample demonstrates how to send a message with MessageAttributes. For more information on MessageAttributes, refer to the official documentation.

var paramsSend = {
    Message: 'MyMessage', 
    Subject: 'MySubject',
    TopicArn: topicARN,
  };
const commandPublishCommand = new PublishCommand(paramsSend);
const restPublishCommand = await snsClient.send(commandPublishCommand);
console.log(restPublishCommand.MessageId);

Subscribe to a topic (NodeJS)Link to this anchor

You can find all available parameters for the subscribe operation in the [AWS documentation] (https://docs.aws.amazon.com/AWSJavaScriptSDK/v3/latest/clients/client-sns/classes/subscribecommand.html)

Subscribe to a public Scaleway function

This code triggers the function each time a message is published to the topic.

You can find the value for [Function URL] in the Scaleway console in the Endpoints tab of your function’s Overview page.

var params = {
    Protocol: 'lambda', 
    TopicArn: topicARN, 
    Endpoint: 'YOUR FUNCTION ENDPOINT',
    ReturnSubscriptionArn: true 
  };
const command = new SubscribeCommand(params);
const rest = await snsClient.send(command);
console.log(rest.SubscriptionArn);

Subscribe to an HTTP/S endpoint

var paramsHttpsSubscription = {
    Protocol: 'https', 
    TopicArn: topicARN, 
    Endpoint: 'YOUR SERVER ENDPOINT',
    ReturnSubscriptionArn: true 
  };
const commandHttpsSubscription = new SubscribeCommand(paramsHttpsSubscription);
const restHttpsSubscription = await snsClient.send(commandHttpsSubscription);
console.log(restHttpsSubscription.SubscriptionArn);

The HTTP server receives an HTTP request with a json body matching the following format:

{
"Type": "SubscriptionConfirmation",
"Token": "<REDACTED-CONFIRMATION-TOKEN>",
"MessageId": "<REDACTED-MESSAGE-ID>",
"TopicArn": "arn:scw:sns:fr-par:<REDACTED-ID>:MyTopic",
"Message": "You have chosen to subscribe to the topic arn:scw:sns:fr-par:<REDACTED-ID>:MyTopic.\nTo confirm the subscription, visit the SubscribeURL included in this message.",
"Timestamp": "2022-06-29T10:03:34Z",
"SignatureVersion": "1",
"Signature": "<REDACTED-SIGNATURE>",
"SigningCertURL": "http://<REDACTED-URL>/SNStest.crt",
"SubscribeURL": "<THE-CONFIRMATION-LINK>" // Get the confirmation link located here
}

To confirm the subscription, make a request to the SubscribeURL using your browser or curl.

Delete all subscriptions (NodeJS)Link to this anchor

The following code sample deletes all subscriptions to a topic.

var paramsListSubs = {
    TopicArn: topicARN, 
  };
const commandListSubs = new ListSubscriptionsByTopicCommand(paramsListSubs);
const restListSubs = await snsClient.send(commandListSubs);
const subscriptionsList = restListSubs.Subscriptions;
subscriptionsList.forEach(async function (element) {
try {
    var params = {
        SubscriptionArn: element.SubscriptionArn 
      };
      const command = new UnsubscribeCommand(params)
      const rest = await snsClient.send(command)
      console.log("Unsubscribing : ",rest.$metadata.httpStatusCode)
} catch (e) {
  throw new Error(e.message)
}
});

Delete all topics (NodeJS)Link to this anchor

The following code sample deletes all your topics.

// First List Topics
const commandList = new ListTopicsCommand({});
const restTopicList = await snsClient.send(commandList);
const TopicList = restTopicList.Topics
// For Each Topic in the list, apply the Delete Topic Command
TopicList.forEach(async function (element) {
    try {
        var params = {
            TopicArn: element.TopicArn 
          };
          const command = new DeleteTopicCommand(params)
          const rest = await snsClient.send(command)
          console.log("Deleting : ",rest.$metadata.httpStatusCode)
    
    } catch (e) {
      throw new Error(e.message)
    }
    });
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