Amazon SNS is a AWS service for Push notifications and Fan-out messaging. GDPR-compliant in EU regions.
What is Amazon SNS?
Amazon Simple Notification Service (SNS) is a fully managed pub/sub messaging service from AWS that enables communication between distributed systems, microservices, and serverless applications. SNS follows the publisher-subscriber pattern: messages are published to topics, and all subscribed endpoints receive the message automatically. This fan-out mechanism allows sending a message to multiple recipients simultaneously without the publisher needing to know the details of the subscribers.
The service supports various protocols and endpoint types: HTTP/HTTPS webhooks, email, SMS, mobile push notifications (iOS, Android, Fire OS), AWS Lambda functions, and SQS queues. This flexibility makes SNS a central component for event-driven architectures where events need to be distributed to multiple downstream systems. Typical scenarios include system notifications, monitoring alerts, status updates in mobile apps, or orchestration of complex workflows.
For European enterprises, SNS is available with full data residency in EU regions. The service offers a 99.9% availability SLA, automatic scaling without capacity planning, and a pay-per-use pricing model. SNS encrypts messages by default in transit and optionally at rest. Seamless integration into the AWS environment enables combination with services like Lambda, SQS, EventBridge, and CloudWatch for comprehensive event-driven solutions.
Common Use Cases for Amazon SNS
1. Event-Driven Architectures
SNS forms the backbone of modern event-driven architectures. When a microservice publishes an event (e.g., “order completed”), all interested services receive this message automatically: the shipping service starts logistics, the billing service creates an invoice, the CRM system updates customer status. This loose coupling enables independent development and scaling of individual components.
2. Mobile Push Notifications
SNS sends push notifications to iOS, Android, and Fire OS devices via their respective platform services (APNs, FCM, ADM). Typical scenarios: transaction confirmations in banking apps, delivery updates in e-commerce apps, breaking news in media apps. SNS handles device token management, retry logic, and platform-specific formatting.
3. System Monitoring and Alerts
CloudWatch alarms trigger SNS topics, which then send notifications to various channels: emails to the ops team, SMS to on-call engineers, HTTP webhooks to PagerDuty or Slack, Lambda functions for automatic remediation. A single alarm can thus serve multiple escalation levels simultaneously.
4. SMS Notifications for Critical Events
SNS sends transactional SMS messages to over 200 countries: two-factor authentication, delivery notifications, payment confirmations, appointment reminders. The service supports sender IDs, long codes, and short codes for professional business communication.
5. Email Notifications
For simple system emails without templates, SNS serves as a cost-effective alternative to SES. Typical use cases: internal status reports, developer notifications for CI/CD events, admin notifications for system changes.
6. Cross-Account and Cross-Region Messaging
SNS topics can send messages to SQS queues or Lambda functions in other AWS accounts or regions. This enables secure communication between organizationally separated environments: centralized logging infrastructure, multi-account strategies, disaster recovery scenarios.
7. Fan-out for Parallel Processing
An SNS message triggers multiple SQS queues or Lambda functions in parallel. Example: an uploaded image is simultaneously converted to different resolutions, analyzed for face recognition, tagged with metadata, and stored in various storage tiers. Each task runs independently with its own retry logic.
Amazon SNS Integration with innFactory
As an AWS Partner, innFactory supports you with:
- Architecture Design: We design scalable, cost-optimized solutions with Amazon SNS
- Migration: Secure transfer of existing workloads to AWS
- Operations & Support: 24/7 monitoring and proactive management
- Cost Optimization: Analysis and optimization of your AWS expenses
- Security & Compliance: GDPR-compliant implementation and certifications
Contact us for a non-binding consultation on Amazon SNS and AWS.
Best Practices for Amazon SNS
1. Establish Topic Naming Conventions
Use descriptive, consistent names with environment and purpose prefixes: prod-order-completed, dev-user-signup, staging-payment-failed. This facilitates IAM policies, monitoring, and cost allocation. Use tags for organizational assignment (team, cost center, project).
2. Leverage Message Filtering
Instead of creating separate topics for each variant, use filter policies in subscriptions. Subscribers only receive messages that meet their filter criteria. This reduces the number of topics, simplifies architecture, and saves costs through fewer unnecessary deliveries.
3. Configure Dead Letter Queues
Configure DLQs for all subscriptions to capture failed deliveries. This prevents data loss and enables subsequent analysis and reprocessing. Monitoring of DLQ metrics should always be active.
4. Enable Encryption
Use AWS KMS for encryption at rest. This is particularly relevant for topics with sensitive data (customer data, transaction information, PII). Encryption is transparent without performance impact.
5. Combine Fan-out Pattern with SQS
For reliable asynchronous processing, combine SNS with SQS: SNS for fan-out, SQS for buffering and retry logic. This completely decouples publishers and consumers and enables individual consumer scaling.
6. FIFO Topics for Ordered Delivery
When message order is critical (e.g., status changes, transaction sequences), use FIFO topics in combination with FIFO SQS queues. Note the lower throughput limits (300 msg/s) compared to standard topics.
7. Monitor CloudWatch Metrics
Set up alarms for NumberOfNotificationsFailed, NumberOfMessagesPublished, and SubscriptionsPending. Also monitor costs per topic to detect unexpected cost spikes early.
Frequently Asked Questions about Amazon SNS
When should I use SNS instead of SQS?
SNS is designed for pub/sub scenarios with multiple recipients (1:n), while SQS serves point-to-point communication (1:1) or as a work queue. Use SNS when an event should trigger multiple independent actions. Combine both: SNS for fan-out, SQS as a buffer for each consumer.
Does SNS support FIFO guarantees?
Yes, since 2020 SNS offers FIFO topics for ordered delivery and exactly-once processing. FIFO topics can only be combined with FIFO SQS queues, not with other protocols. Throughput is limited to 300 transactions/second (or 3,000 with batching).
How do mobile push notifications work with SNS?
You register your app with SNS using the credentials of the respective platform (APNs for iOS, FCM for Android). SNS then manages device tokens, sends messages to platform services, and handles errors (invalid tokens, inactive devices). You can either send directly to individual devices or use topics for topic-based notifications.
What size limits apply to SNS messages?
Standard SNS messages are limited to 256 KB. For larger payloads, use the SNS Extended Client Library, which automatically offloads large messages to S3 and only sends a reference via SNS. SMS messages are limited to 140 bytes (GSM-7) or 70 characters (Unicode) per segment.
How is SNS billed?
SNS charges per published message and per delivery. Prices vary by region and protocol: HTTP/S, SQS, and Lambda are cheapest (approx. $0.50 per 1 million requests), SMS and mobile push cost more (region-dependent). There’s no base fee, no minimum usage, and no provisioning.
Can I filter SNS messages without using Lambda?
Yes, SNS Message Filtering enables declarative filters directly in the subscription. Filters are based on message attributes (JSON-based conditions). Only messages that meet the filter policy are delivered. This saves costs and reduces complexity compared to Lambda-based filtering.
How do I secure SNS topics against unauthorized access?
Use topic policies (resource-based) and IAM policies (identity-based) in combination. Enable HTTPS for subscriptions to prevent man-in-the-middle attacks. Use KMS encryption for sensitive data. Implement subscription confirmation to prevent unauthorized subscriptions. CloudTrail logs all API calls for audit purposes.
Does SNS support cross-region delivery?
Yes, SNS can send messages to endpoints in other regions (e.g., HTTP endpoints, SQS queues in other regions). For multi-region architectures, you typically create topics in each region and replicate messages via EventBridge or Lambda. Note the cross-region data transfer costs.
How do I handle failed deliveries?
Configure Dead Letter Queues (SQS) for each subscription. SNS sends messages to the DLQ when delivery fails after multiple retries. Define retry policies (number of attempts, backoff strategy). Monitor DLQ metrics in CloudWatch and implement alarms for non-empty queues.
Can I use SNS for internal communication in VPCs?
SNS is a public service without VPC endpoints. For VPC-internal communication, combine SNS with VPC endpoints for SQS or Lambda: SNS (outside VPC) → SQS with VPC endpoint → EC2/ECS consumer in VPC. Alternatively, use EventBridge, which supports VPC endpoints, or implement your own message broker pattern with SQS/Kinesis.