AWS SNS & SQS

What is AWS SNS?

AWS Simple Notification Service (SNS) is a fully managed messaging service that allows applications to send notifications to multiple subscribers via email, SMS, push notifications, or AWS services.

Why Use SNS?

  • Allows fan-out architecture (one-to-many message delivery).
  • Supports multiple subscribers (Lambda, SQS, Email, SMS, HTTP endpoints).
  • Provides high availability and durability.
  • Integrates with AWS services like **S3, Lambda, and CloudWatch**.

Creating an SNS Topic

To create an SNS topic and subscribe an email:


aws sns create-topic --name MyTopic
aws sns subscribe --topic-arn arn:aws:sns:us-east-1:123456789012:MyTopic --protocol email --notification-endpoint myemail@example.com
aws sns publish --topic-arn arn:aws:sns:us-east-1:123456789012:MyTopic --message "Hello from SNS!"

What is AWS SQS?

AWS Simple Queue Service (SQS) is a fully managed **message queue** service used to decouple and scale applications.

Why Use SQS?

  • Ensures **asynchronous communication** between services.
  • Supports **standard and FIFO queues**.
  • Handles **millions of messages per second**.
  • Fully integrates with AWS services like **Lambda, EC2, and SNS**.

Types of SQS Queues

  • Standard Queue: Best effort message delivery (unordered).
  • FIFO Queue: First-In-First-Out (guarantees order, limited TPS).

Creating an SQS Queue

To create an SQS queue:


aws sqs create-queue --queue-name MyQueue
aws sqs send-message --queue-url QUEUE_URL --message-body "Hello from SQS!"
aws sqs receive-message --queue-url QUEUE_URL

Integrating SNS with SQS

To send SNS messages to an SQS queue:

  1. Create an SNS topic.
  2. Create an SQS queue.
  3. Subscribe the SQS queue to the SNS topic.
  4. Publish a message to SNS, and SQS will receive it.

aws sns subscribe --topic-arn arn:aws:sns:us-east-1:123456789012:MyTopic \
    --protocol sqs --notification-endpoint arn:aws:sqs:us-east-1:123456789012:MyQueue

Use Cases

  • Order Processing: E-commerce apps use SQS for order queues.
  • Event-Driven Apps: SNS notifies services when an event occurs.
  • IoT & Microservices: SNS and SQS connect different services.

Conclusion

Both SNS and SQS provide reliable communication between AWS services. **SNS is for notifications, while SQS is for message queuing**. Combining them improves scalability and decoupling in modern cloud applications.