Amazon Web Services

IoT Core’s persistent device shadow stores the last reported and desired state of each device in a JSON document, so applications always have a consistent view of device state regardless of network connectivity. Rules Engine evaluates SQL-like expressions on every inbound message and triggers actions — Lambda functions, DynamoDB writes, SNS notifications, SageMaker inference — without provisioning servers. Greengrass extension runs IoT Core message broker and Lambda functions locally on gateway hardware, enabling local device-to-device messaging and edge ML inference during cloud disconnections. MQTT 5.0 support adds user properties, response topic, and message expiry for richer protocol semantics needed by multi-tenant industrial applications. Free tier covers 500,000 messages/month, making it accessible for prototypes and small deployments before scaling costs apply.