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iot-hub-devguide-d2c-guidance.md

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title Azure IoT Hub device-to-cloud options
description This article provides guidance on when to use device-to-cloud messages, reported properties, or file upload for cloud-to-device communications.
author cwatson-cat
ms.author cwatson
ms.service azure-iot-hub
ms.topic concept-article
ms.date 05/22/2025
ms.custom
amqp
mqtt
Role: Cloud Development
Role: IoT Device

Device-to-cloud communications guidance

This article helps you choose the appropriate device-to-cloud communication option in Azure IoT Hub based on your scenario requirements. IoT Hub supports three primary options for device-to-cloud communication: device-to-cloud messages, device twin's reported properties, and file uploads.

Ways to communicate from device to cloud

IoT Hub exposes three options for sending information from the device app to the solution back end:

  • Device-to-cloud messages for time series telemetry and alerts.

  • Device twin's reported properties for reporting device state information such as available capabilities, conditions, or the state of long-running workflows. For example, configuration and software updates.

  • File uploads for media files and large telemetry batches uploaded by intermittently connected devices or compressed to save bandwidth.

[!INCLUDE iot-hub-basic]

Comparison of device-to-cloud communication options

The following table compares the various device-to-cloud communication options in IoT Hub based on common factors.

Factor Device-to-cloud messages Device twin's reported properties File uploads
Scenario Telemetry time series and alerts. For example, 256-KB sensor data batches sent every 5 minutes. Available capabilities and conditions. For example, the current device connectivity mode such as cellular or WiFi. Synchronizing long-running workflows, such as configuration and software updates. Video or other large media files. Large (typically compressed) telemetry batches.
Storage and retrieval Temporarily stored by IoT Hub, up to seven days. Only sequential reading. Stored by IoT Hub in the device twin. Retrievable using the IoT Hub query language. Stored in user-provided Azure Storage account.
Size Up to 256-KB messages. Maximum reported properties size is 32 KB. Maximum file size supported by Azure Blob Storage.
Frequency High. For more information, see IoT Hub quotas and throttling. Medium. For more information, see IoT Hub quotas and throttling. Low. For more information, see IoT Hub quotas and throttling.
Protocol Available on all protocols. Available using MQTT or AMQP. Available when using any protocol, but requires HTTPS on the device.

An application might need to send information both as a telemetry time series or alert and make it available in the device twin. In this scenario, you can choose one of the following options:

  • The device app sends a device-to-cloud message and reports a property change.
  • The solution back end can store the information in the device twin's tags when it receives the message.

Since device-to-cloud messages enable higher throughput than device twin updates, it's sometimes desirable to avoid updating the device twin for every device-to-cloud message.