Device connection state events delayed

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Device connection state events delayed

LeneKaethe 46

I am using Event Grid to forward events from my Azure IoT Hub to a custom webhook. Although I have no issues with "Telemetry" events, "Device Connected" and "Device Disconnected" events are delayed by several seconds. For example, if I connect a device to the Iot Hub and start sending immediately afterwards, the telemetry event is always first and the "Device connected" message takes several seconds to arrive at the webhook. Is there anything I can do to improve the performance of the connection status messages?

Roman Kiss 2,246 Reputation points

2021-06-14T08:59:20.123+00:00

Have a look at the Limitations for device connected and device disconnected events

Thanks
Roman
LeneKaethe 46 Reputation points

2021-06-14T13:07:18.44+00:00

Hi Roman,

thanks a lot for your response!

I read the docs but I can't apply it to my case. I connect to the hub using azure-iot-devcie SDK via MQTT over Ws. Once connected, I send device-to-cloud telemetry messages by calling the client's sendEvent function. Nonetheless, I can send multiple messages before the Device.Connected event arrives. Even if I don't send any telemetry messages, it takes several seconds for the device connection state events to arrive at the webhook. I can't tell any difference in the time duration of the Connected event when I send telemetry messages or not.

I look forward to hearing from you,
Marlene

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Roman Kiss 2,246 Reputation points

2021-06-14T08:59:20.123+00:00

Have a look at the Limitations for device connected and device disconnected events

Thanks
Roman
LeneKaethe 46 Reputation points

2021-06-14T13:07:18.44+00:00

Hi Roman,

thanks a lot for your response!

I read the docs but I can't apply it to my case. I connect to the hub using azure-iot-devcie SDK via MQTT over Ws. Once connected, I send device-to-cloud telemetry messages by calling the client's sendEvent function. Nonetheless, I can send multiple messages before the Device.Connected event arrives. Even if I don't send any telemetry messages, it takes several seconds for the device connection state events to arrive at the webhook. I can't tell any difference in the time duration of the Connected event when I send telemetry messages or not.

I look forward to hearing from you,
Marlene

Answer 1

Roman Kiss 2,246

Hi Marlene,

Based on the mentioned link:
"The Azure IoT Hub doesn't send every single connection state, but publishes the current connection state taken at a periodic snapshot of 60sec until the flickering stops."

In other words, if the device is connected and after 5 seconds is disconnected and then again the device is connected, the IoT Hub will emit only one event message to the AEG such as an eventType = Microsoft.Devices.DeviceConnected.

Note, that the time 60 seconds for snapshotting a device connection state is not configurable.

Thanks
Roman

LeneKaethe 46 Reputation points

2021-06-15T09:16:28.7+00:00

Thanks for patiently explaining, now I get it.
It helps a lot!

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Device connection state events delayed

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