Is Amazon Simple Notification Service (SNS) push-based or pull-based?

Amazon Simple Notification Service (SNS) is classified as a push-based messaging service. This means that SNS sends notifications directly to subscribers or endpoints as soon as a message is published, rather than waiting for the subscribers to request the messages.

In a push-based system like SNS, when a message is published to a topic, it is immediately delivered to all subscribed endpoints – which can include applications, mobile devices, or email addresses. Subscribers do not need to request or poll for new messages; they receive them in real time as they are published. This is particularly useful for use cases that require immediate notification, such as alerting or real-time updates.

The other potential classifications do not accurately reflect how SNS operates. A pull-based system would require subscribers to actively check for new messages (polling), which does not apply to SNS. Hybrid systems would involve characteristics of both push and pull, but SNS does not have this functionality, focusing solely on the push model. Therefore, the classification of SNS as push-based is essential for understanding its design and use cases in managing notification workflows.