SNS

ELI5 — The Vibe Check

SNS is a pub/sub messaging service. One thing publishes a message (like 'new order placed!') and SNS broadcasts it to everyone who's subscribed — email, SMS, Lambda functions, SQS queues, all at once. It's like a group chat where one message goes to every subscriber simultaneously.

Real Talk

Amazon SNS is a fully managed pub/sub messaging service for fan-out patterns. Publishers send to topics; SNS delivers to all subscribers (Lambda, SQS, HTTP endpoints, email, SMS, mobile push). Used for event-driven architectures where one event must trigger multiple downstream actions.

Show Me The Code

// Publish to an SNS topic
import { SNSClient, PublishCommand } from '@aws-sdk/client-sns';
const client = new SNSClient({ region: 'us-east-1' });

await client.send(new PublishCommand({
  TopicArn: 'arn:aws:sns:us-east-1:123:OrderEvents',
  Message: JSON.stringify({ type: 'ORDER_PLACED', orderId: '789' }),
  Subject: 'New Order'
}));

When You'll Hear This

"When a payment completes, we publish to SNS and three services get notified." / "SNS fans out to both SQS and a Lambda for different processing."