Sending messages to IoT hub from Azure Time Trigger Function as device - azure

Question

At the moment Im simulating device where every 30 seconds I send telemetry data to IoT hub.
Here is simple code:
s_deviceClient = DeviceClient.Create(s_iotHubUri, new DeviceAuthenticationWithRegistrySymmetricKey(s_myDeviceId, s_deviceKey), TransportType.Mqtt);
using var cts = new CancellationTokenSource();
var messages = SendDeviceToCloudMessagesAsync(cts.Token);
await s_deviceClient.CloseAsync(cts.Token);
await messages;
cts.Cancel();
And function to send message:
string combinedString = fileStrings[0] + fileStrings[1];
var telemetryDataString = converter.SerializeObject(combinedString);
using var message = new Message(Encoding.UTF8.GetBytes(telemetryDataString))
{
ContentEncoding = "utf-8",
ContentType = "application/json",
};
await s_deviceClient.SendEventAsync(message);
await Task.Delay(interval);
Everything works fine and I created .exe file that was running without problems. But computer where code is running tends to shut-off from time to time which is problematic. So I tried to move this to Azure Time Trigger Function. While in logs everything looks ok, messages aren't actually posted to IoT hub.
I tried to find solution but have not been able to find anything. Is it possible to send messages as device with azure function?

Answer 1

You seem to be closing your DeviceClient before you start using it to send messages. Try the following:
public async Task Do()
{
// Using statement will dispose your client after you're done with it.
// No need to close it manually.
using(var client = DeviceClient.Create(s_iotHubUri, new DeviceAuthenticationWithRegistrySymmetricKey(s_myDeviceId, s_deviceKey), TransportType.Mqtt))
{
// Send messages, await for completion.
await SendDeviceToCloudMessagesAsync(client);
}
}
private async Task SendDeviceToCloudMessagesAsync(DeviceClient client)
{
string combinedString = fileStrings[0] + fileStrings[1];
var telemetryDataString = converter.SerializeObject(combinedString);
using var message = new Message(Encoding.UTF8.GetBytes(telemetryDataString))
{
ContentEncoding = "utf-8",
ContentType = "application/json",
};
await client.SendEventAsync(message);
await Task.Delay(interval);
}