An SNS topic provides high-throughput, push-based, many-to-many messaging. It's a managed service that allows you to send messages to a large number of subscribers, including distributed systems, microservices, and serverless applications. You can use SNS for both application-to-application (A2A) and application-to-person (A2P) communication.

Under the hood, Stacktape uses Amazon Simple Notification Service (SNS).

When to use them

Stacktape offers three managed resources for messaging and communication:

1. SNS topics
2. SQS queues
3. Event buses

Use an SNS topic when:

• You need to publish messages to many different subscribers with a single action.
• You require high throughput and reliability.

Use an SQS queue when:

• You need reliable, one-to-one, asynchronous communication to decouple your applications.
• You want to control the rate at which messages are consumed.

Use an event bus when:

• You want to publish messages to many subscribers and use the event data itself to filter which messages are delivered to which subscribers.
• You need to integrate with third-party SaaS providers like Shopify, Datadog, or PagerDuty.

Basic usage

You don't need to specify any properties to create a basic SNS topic.

resources:
  mainTopic:
    type: sns-topic

Integrating with workloads

You can trigger a function or a batch job whenever a message is published to an SNS topic.

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 the AWS SDK to publish messages to a topic.

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

const snsClient = new SNSClient({});

snsClient.send(
  new PublishCommand({
    Message: "Hello from the other side.",
    TopicArn: process.env.STP_MY_TOPIC_ARN,
  })
);

FIFO

You can enable FIFO (First-In, First-Out) to ensure that messages are processed in the exact order that they are sent.

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

Content-based deduplication

You can enable content-based deduplication to prevent duplicate messages from being sent.