Amazon Simple Notification Service (SNS) is a fully managed messaging service that enables both application-to-application (A2A) and application-to-person (A2P) communication, primarily through a push-based messaging model and fanout architectures (Source: 2, 6, 8). It allows you to decouple and scale microservices, distributed systems, and serverless applications.
Amazon SNS provides scalable, flexible, and cost-effective messaging capabilities.
Amazon SNS is a fully managed messaging service for both application-to-application (A2A) and application-to-person (A2P) communication. It enables fanout architectures. As a push-based messaging service, a producer sends a message to a topic, and messages are then pushed to consumers.
SNS facilitates fanout architectures by distributing messages to multiple consumers. This pattern decouples producers and consumers, scales automatically, and allows multiple consumers to process messages independently at their own pace.
Standard SNS topics do not guarantee message ordering. However, SNS can leverage FIFO topics for strict ordering and deduplication of messages. This is a key differentiator when message order is critical.
SNS is designed for a variety of messaging and notification scenarios.
For applications ingesting messages with drastic and sudden spikes (e.g., up to 100,000/sec), SNS can publish messages to a topic with multiple Amazon SQS subscriptions. Consumer applications then process messages from their respective queues, enabling decoupling and increased scalability for dozens of consuming applications/microservices.
Technical Specs: Up to 100,000 messages/sec ingestion spikes
SNS is used for alerting, especially in scenarios involving Amazon CloudWatch alarms messaging teams or email systems. It can send emails, texts, or any other push-based notifications.
SNS can act as a destination for Amazon S3 Event Notifications, triggering actions in real-time when specific events (e.g., object creation, removal) occur in an S3 bucket. It can also be used with AWS CloudTrail to send notifications when logs are delivered.
SNS supports integration with various AWS services and endpoints for message delivery.
Amazon SQS
SNS topics can fan out messages to Amazon SQS queues, allowing multiple consumers to process messages asynchronously at their own pace.
Use Cases:
- Decoupling microservices
- Buffering messages for asynchronous processing
AWS Lambda
Lambda functions can subscribe to SNS topics to run custom code in response to messages, enabling event-driven processing. However, standard SNS does not guarantee message ordering when triggering Lambda.
Use Cases:
- Real-time data processing
- Automated actions based on events
Email & SMS
SNS can send push-based notifications directly to email addresses and mobile phone numbers (SMS).
Use Cases:
- Alerts
- User notifications
Amazon Kinesis Data Firehose
Kinesis Data Firehose can be a subscriber option for SNS, allowing messages to be reliably delivered to data stores and analytics tools.
Use Cases:
- Loading streaming data to S3, Redshift, OpenSearch
SQS Dead-Letter Queues (DLQ)
For messages that fail to be delivered or processed by SNS subscribers, an SQS Dead-Letter Queue (DLQ) can be configured to capture these failed messages. This helps in troubleshooting and prevents message loss.
Use Cases:
- Saving failed messages for debugging
- Ensuring message durability
Access to SNS topics is managed through policies to ensure secure communication.
Access to SNS topics, including permissions for publishing messages to a topic and subscribing to a topic, is controlled by SNS Topic Access Policies.