Amazon SNS: Simple Notification Service

Amazon Simple Notification Service (SNS) is a fully managed publish-subscribe (pub/sub) messaging service. While SQS provides point-to-point messaging (one producer, one consumer), SNS enables one-to-many communication — a single message published to a topic is delivered to multiple subscribers simultaneously.

---

SQS vs SNS: The Fundamental Difference

Feature	SQS (Queue)	SNS (Topic)
Pattern	Point-to-point	Publish-subscribe
Consumers	One consumer per message	Multiple subscribers per message
Delivery	Consumer polls the queue	SNS pushes to subscribers
Persistence	Messages stored until deleted	No persistence — push and forget
Use case	Work queues, task processing	Notifications, fan-out, broadcasting

---

How SNS Works

The Pub/Sub Model

1. Create a topic — a logical channel for messages
2. Add subscribers — endpoints that want to receive messages
3. Publish a message — the publisher sends a message to the topic
4. SNS delivers — the message is pushed to all subscribers simultaneously