Amazon SNS vs. Amazon SQS

Amazon SNS vs. Amazon SQS: Comprehensive Comparison

When developing applications within AWS, understanding the differences between Amazon Simple Notification Service (SNS) and Amazon Simple Queue Service (SQS) is crucial for effectively managing communication between different components. Below is a detailed comparison in a tabular format to provide clarity on when and why to use each service.

Feature	Amazon SNS	Amazon SQS
Service Type	Pub-sub messaging service	Message queuing service
Communication Model	Publish/subscribe model where messages are sent to multiple subscribers simultaneously.	Queue model where messages are held until a consumer processes them.
Best For	Broadcasting messages to a wide range of subscribers across different platforms.	Decoupling components of a system to process messages individually at their own pace.
Delivery Style	Push notifications, ensuring real-time delivery to all subscribers.	Poll-based, consumers retrieve messages when they’re ready to process them.
Scalability	Automatically scales with the number of messages and subscribers.	Automatically scales to handle large numbers of messages and high throughput.
Message Handling	Each message is sent to every subscriber of the topic.	Each message is processed once, ensuring no duplication in processing.
Subscribers/Consumers	Supports a wide range of subscribers including AWS Lambda, HTTP/S endpoints, emails, SMS.	Consumers typically include EC2 instances, AWS Lambda, or other AWS services.
Use Case Examples	- Real-time alerts and notifications<br>- Triggering synchronous processes across systems	- Job scheduling<br>- Task offloading for asynchronous processing
Message Durability	Messages are not stored, but are immediately delivered to subscribers.	Messages are stored redundantly across multiple servers to ensure they are not lost.
Cost Efficiency	More cost-effective for broadcasting to many subscribers at once.	More cost-effective for high-volume or frequent message transfers with polling.
Integration and Flexibility	High flexibility with various endpoint types.	Primarily integrates within AWS services, though it can be used with external systems.
Typical Application Scenarios	- Notifications systems<br>- Multi-service updates	- Order processing systems<br>- Log processing pipelines

The choice between Amazon SNS and Amazon SQS largely depends on the specific requirements of your application’s architecture. If your application needs real-time, one-to-many messaging, SNS is the suitable choice. Conversely, if your application requires a robust system to handle messages at a controlled throughput, ensuring no message is lost or duplicated, SQS is more appropriate. Both services are designed to be highly available, durable, and scalable, catering to the diverse needs of modern cloud-based applications.