Which AWS service uses a publish/subscribe model for communication?

The Amazon Simple Notification Service (SNS) is designed specifically to use a publish/subscribe model for communication. In this model, messages are sent by publishers to a topic, and multiple subscribers can receive those messages. This allows for a highly scalable and decoupled architecture where different components of an application can interact through messages without needing to know about each other's specifics. When a publisher sends a notification to a topic, all subscribers that have subscribed to that topic receive the message, which fits well into scenarios requiring real-time notifications, alerting systems, and event-driven architectures.

This service is particularly advantageous in situations where system components need to react to events or updates in real time, allowing for efficient data flow and integration across various applications and services within AWS.

In contrast, other options like Amazon Simple Queue Service (SQS) are based on a point-to-point communication model where messages are sent to a queue and processed by single consumers. Amazon EC2 is a compute service without inherent messaging capabilities for publish/subscribe communication. Amazon Lambda, while it can be used with SNS, is also a compute service and serves a different purpose, primarily for running code in response to events.