Amazon SNS Basics

1. Introduction

Amazon Simple Notification Service (SNS) is a fully managed messaging service for both application-to-application (A2A) and application-to-person (A2P) communication. It provides a way to send notifications, alerts, and messages to various recipients.

2. Key Concepts

Topics: A channel for sending messages that multiple subscribers can listen to.
Subscriptions: The endpoints that receive messages from the topic, such as email, SMS, or HTTP/HTTPS endpoints.
Publish: The action of sending a message to a topic.
Endpoints: The recipients of messages, which can be various formats like email, SMS, or AWS Lambda functions.

3. Step-by-Step Setup

Creating an SNS Topic

aws sns create-topic --name MyTopic

This command creates a new SNS topic named "MyTopic".

Subscribing an Email to the Topic

aws sns subscribe --topic-arn arn:aws:sns:us-east-1:123456789012:MyTopic --protocol email --notification-endpoint example@example.com

This command subscribes an email endpoint to the SNS topic.

Publishing a Message

aws sns publish --topic-arn arn:aws:sns:us-east-1:123456789012:MyTopic --message "Hello, World!"

This command sends a message to all subscribers of the topic.

4. Best Practices

Use different topics for different purposes to manage subscriptions effectively.
Implement proper access controls using AWS IAM policies to secure topics.
Monitor SNS usage with AWS CloudWatch to track message delivery and performance.
Consider using dead-letter queues for failed message deliveries.

5. FAQ

What is the maximum message size for SNS?

The maximum size for a message published to SNS is 256 KB.

Can I subscribe multiple endpoints to the same topic?

Yes, you can subscribe multiple endpoints to the same topic, and a single endpoint can subscribe to multiple topics.

Is SNS asynchronous?

Yes, SNS operates asynchronously. When you publish a message, it is immediately returned, and the message is delivered to subscribers in the background.