Amazon SNS (Simple Notification Service)
Amazon SNS is a fully managed pub/sub messaging service that allows you to send messages to multiple subscribers — such as SQS queues, Lambda functions, email, SMS, or HTTP endpoints.
Amazon SNS – Security
| Security Feature | Description |
|---|---|
| IAM Policies | Control which users/services can publish or subscribe. |
| Topic Policies | Fine-grained access control for specific SNS topics. |
| KMS Encryption | Encrypt messages at rest using AWS KMS. |
| HTTPS Endpoints | Secure message delivery to subscribers over SSL. |
| VPC Endpoints (PrivateLink) | Keep traffic within AWS network. |
SNS + SQS: Fan-Out Architecture
Fan-out means publishing a single message to multiple destinations.
💡 How It Works:
- SNS topic receives a message
- SNS delivers it to multiple subscribed SQS queues
- Each queue can process the message independently
📦 Application: S3 Events → SNS → Multiple SQS Queues
Use case: Notify different microservices when a file is uploaded.
Flow:
- S3 Event → triggers SNS
- SNS → fan-out to multiple SQS queues
- Each SQS queue → different consumer/process
🧾 Amazon SNS – FIFO Topics (First-In-First-Out)
- Guarantees exactly-once message delivery
- Maintains strict order
- Use when order and duplication prevention are critical
🔧 Requirements:
- MessageGroupId
- DeduplicationId (optional, or let SNS auto-generate)
🔁 SNS FIFO + SQS FIFO: Fan-Out
- SNS FIFO publishes to multiple SQS FIFO queues
- Ensures:
- Message ordering preserved
- Exactly-once delivery
- Useful for banking, order processing, inventory systems
📌 All queues must be FIFO and use the same MessageGroupId logic
🎯 SNS – Message Filtering
SNS allows subscribers to filter messages based on message attributes (no need to process irrelevant messages).
💡 Example:
🔧 Benefits:
- Reduces unnecessary traffic
- Simplifies consumer logic
📤 SNS → Amazon S3 via Kinesis Data Firehose
SNS can't directly publish to S3. Instead:
Flow:
- SNS → sends message to Kinesis Data Firehose
- Firehose → buffers, batches, and delivers to S3
- Optionally: Firehose transforms data via Lambda
📌 Use case: audit logs, analytics pipelines, IoT messages
✅ Summary Table
| Feature / Pattern | Purpose |
|---|---|
| SNS Security | Control access, encryption, safe delivery |
| SNS + SQS (Fan-out) | Send messages to multiple consumers |
| S3 Events → SNS → SQS | Event-driven architecture for file uploads |
| SNS FIFO | Strict ordering + exactly-once delivery |
| SNS FIFO + SQS FIFO | Reliable, ordered, multi-destination processing |
| SNS Message Filtering | Deliver only relevant messages to subscribers |
| SNS → S3 via Firehose | Persist messages to S3 for analytics/audit |