Large file transfer over AWS IoT Core

Hi. The maximum size of one MQTT payload is 128KB. That cannot be increased. And many IoT devices do not have sufficient RAM to be able to challenge that limit anyway.

The 24MB limit is the maximum size of an MQTT file stream. This is a feature built on top of MQTT, and is mainly used by AWS IoT OTA updates. This feature only works in the cloud-to-device direction.

Since MQTT messages are metered, it's generally not so cost-effective to transfer large files over MQTT, at least not compared to HTTP. So HTTP is often used. This blog details such a pattern, using HTTP, Amazon S3 and presigned URLs: https://aws.amazon.com/blogs/iot/securely-ingesting-large-sized-payloads-from-iot-devices-to-the-aws-cloud/. You can do similar to move large files from cloud-to-device, and AWS IoT Jobs may be of interest too.

What size files will you transfer? Cloud-to-device, device-to-cloud, or both? What sort of device do you have (processing power and memory)? What device software or client will your device run?