Skip to content

AWS Solutions Architect Associate (SAA-C02)

Simple Notification Service (SNS)

  • Used to broadcast messages
  • Pub-Sub model (publisher publishes messages to a topic, subscribers listen to the topic)
  • Instant message delivery (does not queue messages)


  • In-flight encryption by default using HTTPS API
  • At-rest encryption using KMS keys (optional)
  • Client-side encryption

Access Management

  • lAM policies to regulate access to the SNS API
  • SNS Access Policies (resource based policy)
    • Used for cross-account access to SNS topics
    • Used for allowing other AWS services to publish to an SNS topic

Standard Topics

  • Highest throughput
  • At least once message delivery
  • Best effort ordering
  • Subscribers can be:
    • SQS queues
    • HTTP / HTTPS endpoints
    • Lambda functions
    • Emails (using SNS)
    • SMS & Mobile Notifications
    • Kinesis Data Firehose (KDF) to send the data into S3 or Redshift

FIFO Topics

  • Guaranteed ordering of messages in that topic
  • Publishing messages to a FIFO topic requires:
    • Group ID: messages will be ordered and grouped for each group ID
    • Message deduplication ID: for deduplication of messages
  • Can only have SQS FIFO queues as subscribers
  • Limited throughput (same as SQS FIFO) because only SQS FIFO queues can read from FIFO topics
  • The topic name must end with .fifo

SNS + SQS Fanout Pattern

  • Fully decoupled, no data loss
  • SQS allows for: data persistence, delayed processing and retries of work
  • Make sure your SQS queue access policy allows for SNS to write
  • Diagram
    • attachments/Pasted image 20220509205738.jpg

Message Filtering

  • JSON policy used to filter messages sent to SNS topic’s subscriptions
  • Each subscriber will have its own filter policy (if a subscriber doesn’t have a filter policy, it receives every message)
  • Ex: filter messages sent to each queue by the order status

SNS + Lambda + DLQ

  • Lambda retries each failed message 3 times after which it is sent to the DLQ by lambda
    • attachments/Pasted image 20220513220228.jpg

Last updated: 2023-02-21