Digital twin telemetry API not working

Question

I am trying to hit the telemetry Post API https://XXXX.api.weu.digitaltwins.azure.net/digitaltwins/SimpleTwin/telemetry?api-version=2020-10-31

Whenever I am trying to hit the above API either with power automate or through postman the request is not getting completed and getting below error on postman.

Error: socket hang up

▶Request Headers

Content-Type: application/json

Message-Id: e5ca50dd-ca31-4fae-8d84-3af5a72b10c5

Answer 1

Hello @Sukun Jain ,

welcome to this moderated Azure community forum.

It seems you want to execute this command to send telemetry.

I'm not sure what exception you get.

Have you tried this Postman tutorial?

Notice you need to create a bearer token first to get this working. See also the prerequisites.

It is recommended to use the Azure Digital Twins SDK (here is an example found on GitHub).

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Answer 2

Hi @Sukun Jain Greetings! Welcome to Microsoft Q&A forum. Thank you for posting this question here.

I have tested the API Send Telemetry using the Postman and here is how I could send the telemetry.

1. I was prompted to include the Content_Length attribute in the header section. Please find the below image
2. The Content Length attribute has to be set based on your body length. For example, the below body request has content length of 20.

{
    "temp": 59
}

    For a different twin id with a different property name, I have found the Content-Length 33 to work. Here is my         JSON body for this.

{
    "Level_of_Material": 71
}

As Sander pointed, you would also need to add Bearer token under the authorization OAuth 2.0 type. Please refer the Call Azure Digital Twins API with Postman for more details on this.

Kindly note that the content length should match the number of bytes in the request body. If it set to a higher value, I have observed that request keeps running and eventually the connection gets closed.

If your request is successful, you would see a 204 response as below

Please also note that the telemetry data cannot be viewed directly on the Azure Digital Twin explorer. Only property values get stored on the Digital Twin state information.

To monitor the telemetry messages, you would have to an event handler to capture Digital Twin Telemetry Message event triggered by the Digital Twin. Kindly refer to the Model Attributes of DTDL for more information on this.

Hope this helps! Please let us know if you have any additional questions or need further clarification.

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