AWS Simple Notification Service (SNS)

1. SNS is highly scalable push based messaging system (unlike SQS which is pull based).
2. Works on the principle of pub/sub (publish subscribe) protocol
3. Publishers send messages to SNS topic
4. One or more subscribers (programs/lambdas/EC2’s) can subscribe to the topic.
   1. Once subscribed to a topic, all subscriber programs get all the messages PUSHED to it.
   2. No need to poll for the messages unlike the SQS
5. Push notifications can be sent in many ways:
   1. Push messages to Android/ios/fire os devices
   2. SMS text messages
   3. Emails
   4. SQS queues
   5. HTTP REST endpoints
6. SNS achieves redundancy by storing these messages across many Availability Zones in a single region.
7. Protocols used: HTTP, HTTPS, EMAIL, EMAIL-JSON, SQS or Application – messages can be customized for each protocol.
8. SNS messages are stored redundantly to multiple AZs
9. Data format used by SNS is JSON (Subject, Message, TopicArn, MessageId, unsubscribeURL)
10. Cost is based on recipient types.
    • $0.50 per 1 million SNS requests
    • to HTTP: $0.06 / 100,000 notification deliveries
    • to EMAIL: $2 / 100,000 notification deliveries
    • to SMS: $0.75 / 100 notification deliveries