The myriota Azure IoT Hub Cloud Identity Translation Gateway payload formatters use compiled C# code to convert uplink packet payloads to JSON.
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public class FormatterUplink : PayloadFormatter.IFormatterUplink
{
public JObject Evaluate(IDictionary<string, string> properties, string application, string terminalId, DateTime timestamp, byte[] payloadBytes)
{
JObject telemetryEvent = new JObject();
if (payloadBytes is null)
{
return telemetryEvent;
}
telemetryEvent.Add("SequenceNumber", BitConverter.ToUInt16(payloadBytes));
JObject location = new JObject();
double latitude = BitConverter.ToInt32(payloadBytes, 2) / 10000000.0;
location.Add("lat", latitude);
double longitude = BitConverter.ToInt32(payloadBytes, 6) / 10000000.0;
location.Add("lon", longitude);
location.Add("alt", 0);
telemetryEvent.Add("DeviceLocation", location);
UInt32 packetimestamp = BitConverter.ToUInt32(payloadBytes, 10);
DateTime fixAtUtc = DateTime.UnixEpoch.AddSeconds(packetimestamp);
telemetryEvent.Add("FixAtUtc", fixAtUtc);
properties.Add("iothub-creation-time-utc", fixAtUtc.ToString("s", CultureInfo.InvariantCulture));
return telemetryEvent;
}
}
When writing payload formatters, the Visual Studio 2022 syntax highlighting is really useful for spotting syntax errors and with the “Downlink Payload Formatter Test Harness” application payload formatters can be executed and debugged before deployment with Azure Storage Explorer.
private static void ApplicationCore(CommandLineOptions options)
{
Dictionary<string, string> properties = new Dictionary<string, string>();
Console.WriteLine($"Uplink formatter file:{options.FormatterPath}");
PayloadFormatter.IFormatterUplink evalulatorUplink;
try
{
evalulatorUplink = CSScript.Evaluator.LoadFile<PayloadFormatter.IFormatterUplink>(options.FormatterPath);
}
catch (CSScriptLib.CompilerException cex)
{
Console.Write($"Loading or compiling file:{options.FormatterPath} failed Exception:{cex}");
return;
}
byte[] payloadBytes;
try
{
payloadBytes = Convert.FromHexString(options.PayloadHex);
}
catch (FormatException fex)
{
Console.WriteLine("Convert.FromHexString failed:{0}", fex.Message);
return;
}
DateTime timeStamp;
if (options.TimeStamp.HasValue)
{
timeStamp = options.TimeStamp.Value;
}
else
{
timeStamp = DateTime.UtcNow;
}
JObject telemetryEvent;
try
{
telemetryEvent = evalulatorUplink.Evaluate(properties, options.Application, options.TerminalId, timeStamp, payloadBytes);
}
catch (Exception ex)
{
Console.WriteLine($"evalulatorUplink.Evaluate failed Exception:{ex}");
return;
}
telemetryEvent.TryAdd("Application", options.Application);
telemetryEvent.TryAdd("TerminalId", options.TerminalId);
if ( options.TimeStamp.HasValue)
{
telemetryEvent.TryAdd("TimeStamp", options.TimeStamp.Value.ToString("s", CultureInfo.InvariantCulture));
}
telemetryEvent.TryAdd("DataLength", payloadBytes.Length);
telemetryEvent.TryAdd("Data", Convert.ToHexString( payloadBytes));
Console.WriteLine("Properties:");
foreach (var property in properties)
{
Console.WriteLine($"{property.Key}:{property.Value}");
}
Console.WriteLine("");
Console.WriteLine("JSON Telemetry event payload");
Console.WriteLine(telemetryEvent.ToString(Formatting.Indented));
}
-f C:\Users\…\PayloadFormatters\Uplink\tracker.cs -t 0088812345 -a Tracker -h 3800bd9812e6fed5e066bd8e0c65cccccccccccc
The myriota uplink packet payload are only 20 bytes long (40 Hex characters) which can be copied n paste from the uplink queue messages.
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