iot-hub-devguide-messaging.md

title	titleSuffix	description	author	ms.author	ms.service	ms.topic	ms.date	ms.custom
Understand Azure IoT Hub messaging	Azure IoT Hub	This article describes device-to-cloud and cloud-to-device messaging with IoT Hub, with information about message formats and supported communications protocols.	kgremban	kgremban	iot-hub	concept-article	02/23/2024	Role: Cloud Development

Send and receive messages with IoT Hub

IoT Hub enables bi-directional communication with your devices. Use IoT Hub messaging to communicate with your devices by sending messages from your devices to your IoT solution back end, and by sending messages from your IoT solution back end to your devices.

Send device-to-cloud messages to IoT Hub

IoT Hub has a built-in service endpoint that can be used by back-end services to read telemetry messages from your devices. This endpoint is compatible with Azure Event Hubs and you can use standard IoT Hub SDKs to read from this built-in endpoint.

IoT Hub also supports custom endpoints that can be defined by users to send device telemetry data and events to Azure services using message routing.

Learn more about these topics:

• Create and read IoT Hub messages.

• Read device-to-cloud messages from the built-in endpoint

• Understand IoT Hub endpoints

• Use IoT Hub message routing to send device-to-cloud messages to different endpoints

Send cloud-to-device messages from IoT Hub

You can send cloud-to-device messages from the IoT solution back end to your devices.

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Core properties of IoT Hub messaging functionality are the reliability and durability of messages. These properties enable resilience to intermittent connectivity on the device side, and to load spikes in event processing on the cloud side. IoT Hub implements at least once delivery guarantees for both device-to-cloud and cloud-to-device messaging.

Learn more about these topics:

• Send cloud-to-device messages from an IoT hub

Choose the right type of IoT Hub messaging

Use device-to-cloud messages for sending time series telemetry and alerts from your device app, and cloud-to-device messages for one-way notifications to your device app.

Learn more about these topics:

• Understand the use cases for device-to-cloud messages, reported properties, and file upload: Device-to-cloud communications guidance.

• Understand the use cases for cloud-to-device messages, desired properties, and direct methods: Cloud-to-device communications guidance.