Device template format exported from web UI does not work with CLI

Question

I can create a new device template in the Azure IoT Central app UI (at https://apps.azureiotcentral.com). I can also export a device template from this UI.

However, if I use the exported template to create template through the CLI, it doesn't work. In fact, if I run a 'az iot central device-template show' command, I see the device template content wrapped up in some surrounding JSON.

I could not find any documentation of the format for this JSON, and the difference between CLI and UI behavior. I want to find out what is the proper format to work with, and possibly share with others. And why there is this difference

Answer 1

There is a difference in the JSON format between what you can export in the UI and what you can export using 'az iot central device-template show' (or the REST API).

In the UI, you can export a JSON document that's a DTDL v2 document - for more information about DTDL, see https://github.com/Azure/opendigitaltwins-dtdl and https://learn.microsoft.com/azure/iot-develop/overview-iot-plug-and-play. This document is sometimes referred to as a device model. DTDL is used by services other than IoT Central.

Using the CLI (or REST API), you interact with device template. A device template is an IoT Central artifact that is a DTDL model with additional IoT Central specific data. As you pointed out, this document wraps the DTDL model. It also includes additional IoT Central specific information such as:

• Cloud property definitions
• Customizations
• Additional schema elements such as 'displayUnit', 'maxValue', and 'minValue'.