TTI V3 Connector Device EUI Representation

While debugging The Things Industries(TTI) V3 connector on my desktop I had noticed the Device EUI‘s were wrong.

TTI V3 Connector application running as a console application showing incorrect DeviceEUIs

The TTI V3 Connector code…

foreach (V3EndDevice device in endDevices.End_devices)
{
   if (DeviceAzureEnabled(device))
   {
      _logger.LogInformation("Config-ApplicationID:{0} DeviceID:{1} Device EUI:{2}", device.Ids.Application_ids.Application_id, device.Ids.Device_id, BitConverter.ToString(device.Ids.Dev_eui));

      tasks.Add(DeviceRegistration(device.Ids.Application_ids.Application_id, device.Ids.Device_id, _programSettings.ResolveDeviceModelId(device.Ids.Application_ids.Application_id, device.Attributes), stoppingToken));
   }
}

…uses some classes generated by nSwag based on the TheThingsNetwork/LoRaWAN-stack api.swagger.json

public partial class V3EndDeviceIdentifiers 
{
        [Newtonsoft.Json.JsonProperty("device_id", Required = Newtonsoft.Json.Required.Default, NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore)]
        public string Device_id { get; set; }
    
        [Newtonsoft.Json.JsonProperty("application_ids", Required = Newtonsoft.Json.Required.Default, NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore)]
        public V3ApplicationIdentifiers Application_ids { get; set; }
    
        /// <summary>The LoRaWAN DevEUI.</summary>
        [Newtonsoft.Json.JsonProperty("dev_eui", Required = Newtonsoft.Json.Required.Default, NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore)]
        public byte[] Dev_eui { get; set; }
    
        /// <summary>The LoRaWAN JoinEUI (AppEUI until LoRaWAN 1.0.3 end devices).</summary>
        [Newtonsoft.Json.JsonProperty("join_eui", Required = Newtonsoft.Json.Required.Default, NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore)]
        public byte[] Join_eui { get; set; }
    
        /// <summary>The LoRaWAN DevAddr.</summary>
        [Newtonsoft.Json.JsonProperty("dev_addr", Required = Newtonsoft.Json.Required.Default, NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore)]
        public byte[] Dev_addr { get; set; }
}

After some research I found references to the underlying problem in TTN and OpenAPI forums. The Dev_addr and Dev_eui fields are Base16(Hexidecimal) encoded binary but are being processed as if they were Base64(mime) encoded.

The TTI connector only displays the Device EUI so I changed the Dev_eui property to a string

public partial class V3EndDeviceIdentifiers 
{
        [Newtonsoft.Json.JsonProperty("device_id", Required = Newtonsoft.Json.Required.Default, NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore)]
        public string Device_id { get; set; }
    
        [Newtonsoft.Json.JsonProperty("application_ids", Required = Newtonsoft.Json.Required.Default, NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore)]
        public V3ApplicationIdentifiers Application_ids { get; set; }
    
        /// <summary>The LoRaWAN DevEUI.</summary>
        [Newtonsoft.Json.JsonProperty("dev_eui", Required = Newtonsoft.Json.Required.Default, NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore)]
        public string Dev_eui { get; set; }

      /// <summary>The LoRaWAN JoinEUI (AppEUI until LoRaWAN 1.0.3 end devices).</summary>
      [Newtonsoft.Json.JsonProperty("join_eui", Required = Newtonsoft.Json.Required.Default, NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore)]
        public byte[] Join_eui { get; set; }
    
        /// <summary>The LoRaWAN DevAddr.</summary>
        [Newtonsoft.Json.JsonProperty("dev_addr", Required = Newtonsoft.Json.Required.Default, NullValueHandling = Newtonsoft.Json.NullValueHandling.Ignore)]
        public byte[] Dev_addr { get; set; }
}

I also had to remove the BitConverter.ToString call

foreach (V3EndDevice device in endDevices.End_devices)
{
   if (DeviceAzureEnabled(device))
   {
      _logger.LogInformation("Config-ApplicationID:{0} DeviceID:{1} Device EUI:{2}", device.Ids.Application_ids.Application_id, device.Ids.Device_id, device.Ids.Dev_eui);

      tasks.Add(DeviceRegistration(device.Ids.Application_ids.Application_id, device.Ids.Device_id, _programSettings.ResolveDeviceModelId(device.Ids.Application_ids.Application_id, device.Attributes), stoppingToken));
   }
}

Now the DeviceEUI values are displayed correctly and searching for EndDevices in Azure Application Insights is easier

TTI V3 Connector application running as a console application showing correct DeviceEUIs

Modifying the nSwag generated classes is a really nasty way of fixing the problem but I think this approach is okay as it’s only one field and any other solution I could find was significantly more complex.

TTN V3 EndDevice API Basic Client

The next step was to enumerate all the EndDevices of a The Things Network(TTN) Application and display their attributes. I have to establish an Azure DeviceClient connection to an Azure IoT Hub for each TTN EndDevice to get downlink messages. To do this I will have to enumerate the TTN Applications in the instance then enumerate the LoRaWAN EndDevices.

using (HttpClient httpClient = new HttpClient())
{
	EndDeviceRegistryClient endDeviceRegistryClient = new EndDeviceRegistryClient(baseUrl, httpClient)
	{
		ApiKey = apiKey
	};

	try
	{
#if FIELDS_MINIMUM
		string[] fieldMaskPathsDevice = { "attributes" }; // think this is the bare minimum required for integration
#else
		string[] fieldMaskPathsDevice = { "name", "description", "attributes" };
#endif
		V3EndDevices endDevices = await endDeviceRegistryClient.ListAsync(applicationID, field_mask_paths:fieldMaskPathsDevice);
		if ((endDevices != null) && (endDevices.End_devices != null)) // If there are no devices returns null rather than empty list
		{
			foreach (V3EndDevice endDevice in endDevices.End_devices)
			{
#if FIELDS_MINIMUM
				Console.WriteLine($"EndDevice ID:{endDevice.Ids.Device_id}");
#else
				Console.WriteLine($"Device ID:{endDevice.Ids.Device_id} Name:{endDevice.Name} Description:{endDevice.Description}");
				Console.WriteLine($"  CreatedAt: {endDevice.Created_at:dd-MM-yy HH:mm:ss} UpdatedAt: {endDevice.Updated_at:dd-MM-yy HH:mm:ss}");
#endif
				if (endDevice.Attributes != null)
				{
					Console.WriteLine("  EndDevice attributes");

					foreach (KeyValuePair<string, string> attribute in endDevice.Attributes)
					{
						Console.WriteLine($"    Key: {attribute.Key} Value: {attribute.Value}");
					}
				}
				Console.WriteLine();
			}
		}
	}
	catch (Exception ex)
	{
		Console.WriteLine(ex.Message);
	}

	Console.WriteLine("Press <enter> to exit");
	Console.ReadLine();
}

Like the applicationRegistryClient.ListAsync call the endDeviceRegistryClient.ListAsync also returns null rather than an empty list.

I also wanted to explore whether I could use EndDevice attributes to populate the ClientOptions ModelId of my CreateFromConnectionString call. The modelId would contain the Digital Twins Definition Language(DTDL) ID of the LoRaWAN device so it could be automatically provisioned.

TTN V3 Application API Basic Paging and Filtering Client

The next step was to enumerate The Things Network(TTN) Applications so I could connect only to the required Azure IoT hub(s). There would also be a single configuration setting for the client (establish a connection for every TTN application, or don’t establish a connection for any) and this could be overridden with a TTN application attribute

long pageSize = long.Parse(args[3]);
Console.WriteLine($"Page size: {pageSize}");

Console.WriteLine();

using (HttpClient httpClient = new HttpClient())
{
	ApplicationRegistryClient applicationRegistryClient = new ApplicationRegistryClient(baseUrl, httpClient)
	{
		ApiKey = apiKey
	};

	try
	{
		int page = 1;

		string[] fieldMaskPathsApplication = { "attributes" }; // think this is the bare minimum required for integration

		V3Applications applications = await applicationRegistryClient.ListAsync(collaborator, field_mask_paths: fieldMaskPathsApplication, limit: pageSize, page: page);
		while ((applications != null) && (applications.Applications != null)) 
		{
			Console.WriteLine($"Applications:{applications.Applications.Count} Page:{page} Page size:{pageSize}");
			foreach (V3Application application in applications.Applications)
			{
				bool applicationIntegration = ApplicationAzureintegrationDefault;

				Console.WriteLine($"Application ID:{application.Ids.Application_id}");
				if (application.Attributes != null)
				{
					string ApplicationAzureIntegrationValue = string.Empty;
					if (application.Attributes.TryGetValue(ApplicationAzureIntegrationField, out ApplicationAzureIntegrationValue))
					{
						bool.TryParse(ApplicationAzureIntegrationValue, out applicationIntegration);
					}

					if (applicationIntegration)
					{
						Console.WriteLine("  Application attributes");

						foreach (KeyValuePair<string, string> attribute in application.Attributes)
						{
							Console.WriteLine($"   Key: {attribute.Key} Value: {attribute.Value}");
						}
					}
				}
				Console.WriteLine();
			}
			page += 1;
			applications = await applicationRegistryClient.ListAsync(collaborator, field_mask_paths: fieldMaskPathsApplication, limit: pageSize, page: page);
		};
	}
	catch (Exception ex)
	{
		Console.WriteLine(ex.Message);
	}

	Console.WriteLine("Press <enter> to exit");
	Console.ReadLine();
}

I Used the field_mask_paths parameter (don’t need created_at, updated_at, name etc.) to minimise the data returned to my client.

public async System.Threading.Tasks.Task<V3Applications> ListAsync(string collaborator_organization_ids_organization_id = null, string collaborator_user_ids_user_id = null, string collaborator_user_ids_email = null, System.Collections.Generic.IEnumerable<string> field_mask_paths = null, string order = null, long? limit = null, long? page = null, System.Threading.CancellationToken cancellationToken = default(System.Threading.CancellationToken))
{
   var urlBuilder_ = new System.Text.StringBuilder();
   urlBuilder_.Append(BaseUrl != null ? BaseUrl.TrimEnd('/') : "").Append("/applications?");
   if (collaborator_organization_ids_organization_id != null) 
   {
         urlBuilder_.Append(System.Uri.EscapeDataString("collaborator.organization_ids.organization_id") + "=").Append(System.Uri.EscapeDataString(ConvertToString(collaborator_organization_ids_organization_id, System.Globalization.CultureInfo.InvariantCulture))).Append("&");
   }
   if (collaborator_user_ids_user_id != null) 
   {
         urlBuilder_.Append(System.Uri.EscapeDataString("collaborator.user_ids.user_id") + "=").Append(System.Uri.EscapeDataString(ConvertToString(collaborator_user_ids_user_id, System.Globalization.CultureInfo.InvariantCulture))).Append("&");
   }
   if (collaborator_user_ids_email != null) 
   {
         urlBuilder_.Append(System.Uri.EscapeDataString("collaborator.user_ids.email") + "=").Append(System.Uri.EscapeDataString(ConvertToString(collaborator_user_ids_email, System.Globalization.CultureInfo.InvariantCulture))).Append("&");
   }
   if (field_mask_paths != null) 
   {
         foreach (var item_ in field_mask_paths) { urlBuilder_.Append(System.Uri.EscapeDataString("field_mask.paths") + "=").Append(System.Uri.EscapeDataString(ConvertToString(item_, System.Globalization.CultureInfo.InvariantCulture))).Append("&"); }
   }
   if (order != null) 
   {
         urlBuilder_.Append(System.Uri.EscapeDataString("order") + "=").Append(System.Uri.EscapeDataString(ConvertToString(order, System.Globalization.CultureInfo.InvariantCulture))).Append("&");
   }
   if (limit != null) 
   {
         urlBuilder_.Append(System.Uri.EscapeDataString("limit") + "=").Append(System.Uri.EscapeDataString(ConvertToString(limit, System.Globalization.CultureInfo.InvariantCulture))).Append("&");
   }
   if (page != null) 
   {
         urlBuilder_.Append(System.Uri.EscapeDataString("page") + "=").Append(System.Uri.EscapeDataString(ConvertToString(page, System.Globalization.CultureInfo.InvariantCulture))).Append("&");
   }
}

I was hoping that there would be a away to further “shape” the returned data, but in the NSwag generated code the construction of the URL with field_mask_paths, order, limit, and page parameters meant this appears not to be possible.

TTN V3 Application API Basic Paging Client

The next step was to enumerate The Things Network(TTN) Applications and their attributes. I’m planning on using attributes to manage which applications (and in future EndDevices) are enabled in my Advanced Message Queuing Protocol(AMQP) client.

In the code I have left the different paging implementations which I trialled but abandoned.

using (HttpClient httpClient = new HttpClient())
{
	ApplicationRegistryClient applicationRegistryClient = new ApplicationRegistryClient(baseUrl, httpClient)
	{
		ApiKey = apiKey
	};

	try
	{
		int page = 1;
		string[] fieldMaskPathsApplication = { "attributes" };

		V3Applications applications = await applicationRegistryClient.ListAsync(collaborator, field_mask_paths: fieldMaskPathsApplication, limit:pageSize, page: page);
		while ((applications != null) && (applications.Applications != null))
		{ 
			Console.WriteLine($"Applications:{applications.Applications.Count} Page:{page} Page size:{pageSize}");
			foreach (V3Application application in applications.Applications)
			{
				Console.WriteLine($"Application ID:{application.Ids.Application_id}"); 
				if (application.Attributes != null)
				{
					Console.WriteLine("  Application attributes");

					foreach (KeyValuePair<string, string> attribute in application.Attributes)
					{
						Console.WriteLine($"   Key: {attribute.Key} Value: {attribute.Value}");
					}
				}
				Console.WriteLine();
			}
			page += 1;
			applications = await applicationRegistryClient.ListAsync(collaborator, field_mask_paths: fieldMaskPathsApplication, limit: pageSize, page: page);
		}
	}   
}

For each LoraWAN client I have to have an open connection to the Azure IoT hub to get Cloud to Device (C2D) messages so I’m looking at using connection pooling to reduce the overall number of connections.

I think the Azure ClientDevice library supports up to 995 devices per connection and has quiet a lot of additional functionality.

/// <summary>
/// contains Amqp Connection Pool settings for DeviceClient
/// </summary>
public sealed class AmqpConnectionPoolSettings
{
   private static readonly TimeSpan s_defaultConnectionIdleTimeout = TimeSpan.FromMinutes(2);
    private uint _maxPoolSize;
    internal const uint MaxDevicesPerConnection = 995; // IotHub allows upto 999 tokens per connection. Setting the threshold just below that.

    /// <summary>
    /// The default size of the pool
    /// </summary>
    /// <remarks>
    /// Allows up to 100,000 devices
    /// </remarks>
    private const uint DefaultPoolSize = 100;

    /// <summary>
    /// The maximum value that can be used for the MaxPoolSize property
    /// </summary>
     public const uint AbsoluteMaxPoolSize = ushort.MaxValue;

    /// <summary>
    /// Creates an instance of AmqpConnecitonPoolSettings with default properties
    /// </summary>
    public AmqpConnectionPoolSettings()
    {
       _maxPoolSize = DefaultPoolSize;
       Pooling = false;
    }

Whereas I think AMQPNetLite may support more, but will require me to implement more of the Azure IoT client interface

/// <summary>
/// The default maximum frame size used by the library.
/// </summary>
public const uint DefaultMaxFrameSize = 64 * 1024;
internal const ushort DefaultMaxConcurrentChannels = 8 * 1024;
internal const uint DefaultMaxLinkHandles = 256 * 1024;
internal const uint DefaultHeartBeatInterval = 90000;
internal const uint MinimumHeartBeatIntervalMs = 5 * 1000;

I have got todo some more research to see which library is easier/requires more code/complex/scales better.

TTN V3 Application API Basic Client

After reviewing the initial implementation I found I had to have one connection per The Things Network(TTN) device. Todo this I first have to enumerate the LoRaWAN Devices for each Application in my instance. First I had to add the TTN APIKey to the application and device registry requests.

namespace devMobile.TheThingsNetwork.API
{
	public partial class EndDeviceRegistryClient
	{
		public string ApiKey { set; get; }

		partial void PrepareRequest(System.Net.Http.HttpClient client, System.Net.Http.HttpRequestMessage request, string url)
		{
			if (!client.DefaultRequestHeaders.Contains("Authorization"))
			{
				client.DefaultRequestHeaders.Add("Authorization", $"Bearer {ApiKey}");
			}
		}
	}

	public partial class ApplicationRegistryClient
	{
		public string ApiKey { set; get; }

		partial void PrepareRequest(System.Net.Http.HttpClient client, System.Net.Http.HttpRequestMessage request, string url)
		{
			if (!client.DefaultRequestHeaders.Contains("Authorization"))
			{
				client.DefaultRequestHeaders.Add("Authorization", $"Bearer {ApiKey}");
			}
		}
	}
}

The first step was to enumerate Applications and their attributes

#if FIELDS_MINIMUM
	string[] fieldMaskPathsApplication = { "attributes" }; // think this is the bare minimum required for integration
#else
	string[] fieldMaskPathsApplication = { "name", "description", "attributes" };
#endif

	V3Applications applications = await applicationRegistryClient.ListAsync(collaborator, field_mask_paths: fieldMaskPathsApplication);
	if ((applications != null) && (applications.Applications != null)) // If there are no applications returns null rather than empty list
	{
		foreach (V3Application application in applications.Applications)
		{
#if FIELDS_MINIMUM
			Console.WriteLine($"Application ID:{application.Ids.Application_id}");
#else
			Console.WriteLine($"Application ID:{application.Ids.Application_id} Name:{application.Name} Description:{application.Description}");
			Console.WriteLine($"  CreatedAt: {application.Created_at:dd-MM-yy HH:mm:ss} UpdatedAt: {application.Updated_at:dd-MM-yy HH:mm:ss}");
#endif
			if (application.Attributes != null)
			{
				Console.WriteLine("  Application attributes");

				foreach (KeyValuePair<string, string> attribute in application.Attributes)
				{
					Console.WriteLine($"    Key: {attribute.Key} Value: {attribute.Value}");
				}
			}
			Console.WriteLine();
		}
	}
}

The applicationRegistryClient.ListAsync call returns null rather than an empty list which tripped me up. I only found this when I deleted all the applications in my instance and started from scratch.

The Things Network Client Part2

MQTT connectivity

In a previous post I couldn’t add a TTN V3EndDevice to an application (I’m going try again soon) using the REST API so I figured would try out the MQTT API. My aim was to get notifications of when a Device was created/updated/deleted in an Application.

After some tinkering with the format of MQTT usernames and passwords I can connect to my V3 instance and successfully subscribe to topics. But, currently(Aug 2020) I’m not receiving any messages when I create, update or delete a Device. I have tried different Quality of Service QoS settings etc. and I wonder if my topic names aren’t quite right.

.Net Core MQTT Client

I wanted notifications so I could “automagically” provision a device in an Azure IoT Hub (maybe with a tag indicating it’s an “orphan” so it is discoverable) or in Azure IoT Central when a Device was created in TTN.

This looked like a good approach as my Azure IoT Hub applications have other devices which are not connected via LoRaWAN, and there are many specialised LoRaWAN settings which would need to be validated, stored etc. by my software. (maybe TTN device templates would make this easier). The TTN software is pretty good at managing devices so why would I “re-invent the wheel”.

I built a “nasty” console application using MQTTNet so that I could figure out how to connect to my V3 setup and subscribe to topics.

namespace devMobile.TheThingsNetwork.MqttClient
{
   using System;
   using System.Diagnostics;
   using System.Threading;
   using System.Threading.Tasks;

   using MQTTnet;
   using MQTTnet.Client;
   using MQTTnet.Client.Disconnecting;
   using MQTTnet.Client.Options;
   using MQTTnet.Client.Receiving;
   using MQTTnet.Client.Subscribing;

   class Program
   {
      private static IMqttClient mqttClient = null;
      private static IMqttClientOptions mqttOptions = null;
      private static string server;
      private static string username;
      private static string password;
      private static string clientId;

      static async Task Main(string[] args)
      {
         MqttFactory factory = new MqttFactory();
         mqttClient = factory.CreateMqttClient();

         if (args.Length != 4)
         {
            Console.WriteLine("[MQTT Server] [UserName] [Password] [ClientID]");
            Console.WriteLine("Press <enter> to exit");
            Console.ReadLine();
            return;
         }

         server = args[0];
         username = args[1];
         password = args[2];
         clientId = args[3];

         mqttOptions = new MqttClientOptionsBuilder()
            .WithTcpServer(server)
            .WithCredentials(username, password)
            .WithClientId(clientId)
            .WithTls()
            .Build();

         mqttClient.UseDisconnectedHandler(new MqttClientDisconnectedHandlerDelegate(e => MqttClient_Disconnected(e)));
         mqttClient.UseApplicationMessageReceivedHandler(new MqttApplicationMessageReceivedHandlerDelegate(e => MqttClient_ApplicationMessageReceived(e)));
         await mqttClient.ConnectAsync(mqttOptions);

         // Different topics I have tried
         string topic;
         topic = $"v3/{username}/devices/{clientId}/events/update";
         //topic = $"v3/{username}/devices/{clientId}/events/create";
         //topic = $"v3/{username}/devices/{clientId}/events/delete";
         //topic = $"v3/{username}/devices/+/events/+";
         //topic = $"v3/{username}/devices/+/events/create";
         //topic = $"v3/{username}/devices/+/events/update";
         //topic = $"v3/{username}/devices/+/events/delete";
         //topic = $"v3/{username}/devices/+/events/+";

         MqttClientSubscribeResult result;

         // Different QoS I have tried
         //result = await mqttClient.SubscribeAsync(topic, MQTTnet.Protocol.MqttQualityOfServiceLevel.AtMostOnce);
         result = await mqttClient.SubscribeAsync(topic, MQTTnet.Protocol.MqttQualityOfServiceLevel.AtLeastOnce);
         //result = await mqttClient.SubscribeAsync(topic, MQTTnet.Protocol.MqttQualityOfServiceLevel.ExactlyOnce);

         Console.WriteLine("SubscribeAsync Result");
         foreach ( var resultItem in result.Items)
         {
            Console.WriteLine($"ResultCode:{resultItem.ResultCode} TopicFilter:{resultItem.TopicFilter}");
         }                     

         Console.WriteLine("Press any key to temrminate wait");
         while (!Console.KeyAvailable)
         {
            Console.Write(".");

            Thread.Sleep(30100);
         }

         Console.WriteLine("Press <enter> to exit");
         Console.ReadLine();
         return;
      }

      private static void MqttClient_ApplicationMessageReceived(MqttApplicationMessageReceivedEventArgs e)
      {
         Console.WriteLine($"ClientId:{e.ClientId} Topic:{e.ApplicationMessage.Topic} Payload:{e.ApplicationMessage.ConvertPayloadToString()}");
      }

      private static async void MqttClient_Disconnected(MqttClientDisconnectedEventArgs e)
      {
         Debug.WriteLine("Disconnected");
         await Task.Delay(TimeSpan.FromSeconds(5));

         try
         {
            await mqttClient.ConnectAsync(mqttOptions);
         }
         catch (Exception ex)
         {
            Debug.WriteLine("Reconnect failed {0}", ex.Message);
         }
      }
   }
}

I’m going to post some questions on the TTN forums and Slack community to see if what I’m trying to do is supported/possible.

I got some helpful responses on the TTN forums and it looks like what I want todo is not supported by the V3 stack (Aug2020) and I will have to use gRPC.

The Things Network Client Part1

Basic connectivity

Over the last few months I have been using the community version of The Things Network(TTN) to test my LoRaWAN RakWireless RAK811 EVB based nanoFramework and TinyCLR clients.

As I was manually configuring TTN clients references to an application programming interface(API) caught my attention. In my day job I use tools from SmartBear and RicoSuter to generate .Net Core clients (for APSP.NET Core Web APIs I have build) from their OpenAPI descriptions.

The first step was to download the API swagger from The Things Network Github repository.

Things Network Github repository

I then used nSwagStudio to generate a C# client from a local copy of the API swagger (in the future I will use download the swagger and use the command line tools).

nSwag User Interface

At this point I had a basic client for the TTN network stack API which lacked support for the TTN security model etc. After looking at the TTN API documentation I figured out I need to add a header which contained an API Key from the TTN application configuration.

namespace TheThingsNetwork.API
{
	public partial class EndDeviceRegistryClient
	{
		public string ApiKey { set; get; }

		partial void PrepareRequest(System.Net.Http.HttpClient client, System.Net.Http.HttpRequestMessage request, string url)
		{
			if (!client.DefaultRequestHeaders.Contains("Authorization"))
			{
				client.DefaultRequestHeaders.Add("Authorization", $"Bearer {ApiKey}");
			}
		}
	}
}

In the TTN console on the overview page for my application I created an Access Key.

I then added some attributes to one of my devices so I had some addition device configuration data to display(I figured these could be useful for Azure IoT Hub configuration parameters etc. more about this later..)

Basic Device configuration in TTN Enterprise

I built a nasty console application which displayed some basic device configuration information to confirm I could authenticate and enumerate.

//---------------------------------------------------------------------------------
// Copyright (c) August 2020, devMobile Software
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// SECURITY_ANONYMISE
//---------------------------------------------------------------------------------
namespace TheThingsNetwork.EndDeviceClient
{
	using System;
	using System.Collections.Generic;
	using System.Net.Http;
	using TheThingsNetwork.API;

	class Program
	{
		static void Main(string[] args)
		{
			Console.WriteLine("TheThingsNetwork.EndDeviceClient starting");

			if (args.Length != 3)
			{
				Console.WriteLine("EndDeviceClient <baseURL> <applicationId> <apiKey>");
				Console.WriteLine("Press <enter> to exit");
				Console.ReadLine();
				return;
			}
			string baseUrl = args[0];
#if !SECURITY_ANONYMISE
			Console.WriteLine($"baseURL: {baseUrl}");
#endif
			string applicationId = args[1];
#if !SECURITY_ANONYMISE
			Console.WriteLine($"applicationId: {applicationId}");
#endif
			string apiKey = args[2];
#if !SECURITY_ANONYMISE
			Console.WriteLine($"apiKey: {apiKey}");
			Console.WriteLine();
#endif

			using (HttpClient httpClient = new HttpClient())
			{
				EndDeviceRegistryClient endDeviceRegistryClient = new EndDeviceRegistryClient(baseUrl, httpClient);
				endDeviceRegistryClient.ApiKey = apiKey;

				try
				{
					V3EndDevices endDevices = endDeviceRegistryClient.ListAsync(applicationId).GetAwaiter().GetResult();

					foreach (V3EndDevice v3EndDevice in endDevices.End_devices)
					{
#if SECURITY_ANONYMISE
						v3EndDevice.Ids.Dev_eui[7] = 0x0;
						v3EndDevice.Ids.Dev_eui[8] = 0x0;
						v3EndDevice.Ids.Dev_eui[9] = 0x0;
						v3EndDevice.Ids.Dev_eui[10] = 0x0;
						v3EndDevice.Ids.Dev_eui[11] = 0x0;
#endif
						Console.WriteLine($"Device ID:{v3EndDevice.Ids.Device_id} DevEUI:{Convert.ToBase64String(v3EndDevice.Ids.Dev_eui)}");
						Console.WriteLine($"   CreatedAt: {v3EndDevice.Created_at:dd-MM-yy HH:mm:ss} UpdatedAt: {v3EndDevice.Updated_at:dd-MM-yy HH:mm:ss}");

						string[] fieldMaskPaths = { "name", "description", "attributes" };

						var endDevice = endDeviceRegistryClient.GetAsync(applicationId, v3EndDevice.Ids.Device_id, field_mask_paths: fieldMaskPaths).GetAwaiter().GetResult();

						Console.WriteLine($"   Name: {endDevice.Name}");
						Console.WriteLine($"   Description: {endDevice.Description}");
						if (endDevice.Attributes != null)
						{
							foreach (KeyValuePair<string, string> attribute in endDevice.Attributes)
							{
								Console.WriteLine($"      Key: {attribute.Key} Name: {attribute.Value}");
							}
						}
						Console.WriteLine();
					}
				}
				catch (Exception ex)
				{
					Console.WriteLine(ex.Message);
				}

				Console.WriteLine("Press <enter> to exit");
				Console.ReadLine();
			}
		}
	}
}

I added some code so I could anonymise the displayed configuration so I could take screen grabs without revealing any sensitive information.

TTN API Client V1

Initially I struggled with versioning issues as the TTN community network is running V2 and the github repository was for V3. I approached TTN and they gave me access to a “limited” account on the enterprise network.

I also struggled with the number of blank fields in responses and spent some time learning GO (the programming language TTN is built with) to figure out how to use fieldMaskPaths etc.

string[] fieldMaskPaths = { "name", "description", "attributes" };

V3EndDevice endDevice = endDeviceRegistryClient.GetAsync(applicationId, v3EndDevice.Ids.Device_id, field_mask_paths: fieldMaskPaths).GetAwaiter().GetResult();

Overall things went pretty well but I expect to basic GO programing skills one this project is finished.

As hinted at earlier in this post the end goal of this project is to build an Azure IoT hub integration.

AdaFruit IO Swagger based desktop HTTP client

Manually building clients for complex RESTful APIs (like AdaFruit.IO) can be a bit tedious so I figured I would try generating a C# http client from the Swagger OpenAPI specification(OAS) metadata.

My initial attempts using the Swagger Editor and NSwag on the AdaFruit.IO public API description didn’t go so well. (for more info see this AdaFruit.IO support forum thread) You may need to manually modify the type of the id field in Data & DataResponse, plus possibly other responses.

After figuring out how to set the API key, my code which uploads simulates three individual feeds and one feed group appears to work reliably.

/*

Copyright ® 2018 Jan devMobile Software, All Rights Reserved

THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
PURPOSE.

http://www.devmobile.co.nz

 */
using System;
using System.Diagnostics;
using System.Threading.Tasks;
using AdaFruit.IO;

namespace AdaFruit.IO
{
   public partial class Client
   {
      string adaFruitIOApiKey = "yourAPIKey";

      partial void PrepareRequest(System.Net.Http.HttpClient client, System.Net.Http.HttpRequestMessage request, string url)
      {
         client.DefaultRequestHeaders.Add("X-AIO-Key", adaFruitIOApiKey);
      }
   }
}

namespace devMobile.IoT.Adafruit.IO.Desktop
{
   class Program
   {
      static void Main(string[] args)
      {
         string userName = "YourUserName"; // This is mixed case & case sensitive
         // The feed group and feed key are forced to lower case by UI
         const string feedGroup = "devduinov2-dot-2";
         const string temperatureKey = "t";
         const double temperatureBase = 20.0;
         const double temperatureRange = 10.0;
         const string humidityKey = "h";
         const double humidityBase = 70.0;
         const double humidityRange = 20.0;
         const string batteryVoltageKey = "v";
         const double batteryVoltageBase = 3.00;
         const double batteryVoltageRange = -1.00;
         TimeSpan feedUpdateDelay = new TimeSpan(0, 0, 15);
         TimeSpan groupUpdateDelay = new TimeSpan(0, 0, 30);
         Random random = new Random();

         while (true)
         {
            Client client = new Client();
            double temperature = temperatureBase + random.NextDouble() * temperatureRange;
            double humidity = humidityBase + random.NextDouble() * humidityRange;
            double batteryVoltage = batteryVoltageBase + random.NextDouble() * batteryVoltageRange;

            Debug.WriteLine("Temperature {0}°C  Humidity {1}%  Battery Voltage {2}V", temperature.ToString("F1"), humidity.ToString("F0"), batteryVoltage.ToString("F2"));

            // First Update the 3 feeds individually
            // Temperature
            Datum temperatureDatum = new Datum()
            {
               Value = temperature.ToString("F1"),
            };
            client.CreateDataAsync(userName, temperatureKey, temperatureDatum).Wait();
            Task.Delay(feedUpdateDelay).Wait();

            // Humidity
            Datum humidityDatum = new Datum()
            {
               Value = humidity.ToString("F0"),
            };
            client.CreateDataAsync(userName, humidityKey, humidityDatum).Wait();
            Task.Delay(feedUpdateDelay).Wait();

            // Battery
            Datum batteryDatum = new Datum()
            {
               Value = batteryVoltage.ToString("F2"),
            };
            client.CreateDataAsync(userName, batteryVoltageKey, batteryDatum).Wait();
            Task.Delay(feedUpdateDelay).Wait();

            // Then update a feed in a group
            Group_feed_data devDuinoData = new Group_feed_data();

            devDuinoData.Feeds.Add(new Anonymous2() { Key = temperatureKey, Value = temperature.ToString("F1")});
            devDuinoData.Feeds.Add(new Anonymous2() { Key = humidityKey, Value = humidity.ToString("F0")});
            devDuinoData.Feeds.Add(new Anonymous2() { Key = batteryVoltageKey, Value = batteryVoltage.ToString("F2")});

            client.CreateGroupDataAsync(userName, feedGroup, devDuinoData).Wait();
            Task.Delay(groupUpdateDelay).Wait();
         }
      }
   }
}