What's the difference between AWS SQS and SNS?

If you're building a serverless application on AWS, you may have come across Amazon Simple Queue Service (SQS) and Amazon Simple Notification Service (SNS). These two services, along with AWS Lambda, form the core of the serverless offering from Amazon Web Services (AWS).

But what's the difference between SQS and SNS?

At a high level, SQS is a message queue service that enables asynchronous communication between decoupled components of a distributed application, while SNS is a messaging service that allows you to send notifications or messages to multiple subscribers. This means that SQS provides a reliable, highly scalable, and durable queue for storing messages, while SNS provides a way to quickly send messages to multiple subscribers.

One key difference between SQS and SNS is the way in which messages are delivered.

SQS is a pull-based delivery system, which means that the consumer of the messages is responsible for pulling messages from the queue and processing them. In contrast, SNS is a push-based delivery system, which means that the service automatically pushes messages to the subscribed endpoints.

Another difference is the type of workloads that SQS and SNS are designed for. SQS is ideal for processing large numbers of messages in a reliable and scalable manner, making it a good choice for background tasks, batch jobs, and other types of workloads that can be parallelized. SNS, on the other hand, is better suited for time-critical, high-throughput workloads that require immediate processing of messages, such as mobile push notifications or real-time alerts.

One common use case for SQS and SNS is to build a serverless event-driven architecture, where events trigger the execution of code in AWS Lambda.

For example, you can use SQS to buffer incoming events, and then use SNS to push those events to one or more Lambda functions for processing. This allows you to scale your application horizontally by adding more Lambda functions, without having to worry about managing the underlying infrastructure.

In summary, SQS and SNS are two powerful services that can help you build scalable, resilient, and cost-effective serverless applications on AWS. While SQS provides a reliable queue for storing and processing messages, SNS allows you to easily send notifications or messages to multiple subscribers.

Together, these services form the foundation of many serverless architectures on AWS.