Overview and basic concepts

SNS topic provides high-throughput, push-based, many-to-many messaging between distributed systems, microservices, and event-driven serverless applications.

SNS topic can be easily used for both A2A(application to application) and A2P(application to person) notifications by easily integrating with lambda functions, HTTPS endpoints, emails, or sending SMS.

Under the hood

SNS topic is an abstraction for Amazon Simple Notification Service (SNS).

When to use

Stacktape offers 3 types of AWS managed resources intended for messaging/communication(all use "pay per use" model and scale automatically):

1. AWS SNS topic
2. AWS SQS queue
3. AWS EventBridge bus

Depending on you use case you might choose to use:

Use SNS topic when

• You want to publish messages to MANY different subscribers with a single action.
• Require high throughput and reliability for publishing and delivery to consumers.
• Have many subscribers.

Use SQS queue when

• You are looking for reliable 1:1 asynchronous communication to decouple your applications from one another
• You want to rate limit your consumption of messages (in case of SQS consumer fetches the messages so you can control the rate)

Use Event bus when

• You want to publish messages to many subscribers, and use the event data itself to match targets interested certain patterns (with even bus, you can filter which messages should be delivered to the subscriber based on message content)
• You want integration with other SaaS providers such as Shopify, Datadog, Pagerduty, or others.

Basic usage

By default sns-topic does not need to have any properties defined.

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resources:
  mainTopic:
    type: sns-topic

Integrating with workloads

You can invoke function or a batch-job every time message is delivered to sns-topic. This can be done simply by creating event integration.

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resources:
  myLambda:
    type: function
    properties:
      packaging:
        type: stacktape-lambda-buildpack
        properties:
          entryfilePath: path/to/my-lambda.ts
      events:
        - type: sns
          properties:
            snsTopicName: mySnsTopic

  mySnsTopic:
    type: sns-topic

Publishing messages

You can use AWS SDK to publish messages to the topic.

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import { PublishCommand, SNSClient } from "@aws-sdk/client-sns";

const sqsClient = new SNSClient({});

sqsClient
  .send(new PublishCommand({ Message: "Hello from the other side.", TopicArn: process.env.STP_MY_TOPIC_ARN }))
  .catch((err) => {
    console.info(`Sending message failed: ${err}`);
  });

Enabling FIFO

You can enable FIFO(First in First Out) for your SNS topic, ensuring ordering of events.

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resources:
  mainTopic:
    type: sns-topic
    properties:
      fifoEnabled: true

Content based deduplication