[AWS] Amazon SNS

SNS is a fully managed pub/sub message delivery service hat enables you to decouple microservices, distributed systems, and serverless applications.

---

Features

SNS can be used for event notification, notifying admins of system alerts (CloudWatch), mobile push (no polling) notification.

• Messages (<= 256 KB) are sent to a topic and delivered to subscribers.
  • Typically, JSON key-value pairs
• Resource policies define who can access a topic.
  • For some AWS services (EC2 or Lambda), IAM roles are used.

---

SNS Components

• Topic
  • A configuration for SNS. Messages are sent to a topic.
  • FIFO vs. Standard
    • In most cases, you can use the standard topic
    • If you need the strictly-preserved message ordering, you can use the FIFO topic.
    • A subscriber to a FIFO topic must be SQS.
      
• Subscriber
  • Endpoints that receive a message
  • HTTP, Email, SQS, Lambda, or Mobile push notification
  • A subscriber can filter messages from the topic by assigning a filter policy.
• Publisher
  • An entity that sends messages to a topic
  • Custom Application, S3, CloudWatch, or CloudFormation

---

SNS Benefits

• SNS Can be used with the AWS Console, API, CLI, and multiple SDKs.

Use Cases

• Using Amazon SNS topics, publisher systems can fan out messages to a large number of subscriber endpoints for parallel processing, including Amazon SQS queues, AWS Lambda functions, and HTTP/S webhooks.
• Additionally, SNS can be used to fan out notifications to end users using mobile push, SMS, and email.