Implement TelemetryPublisherFactory

NucuCar.Domain/Telemetry/TelemetryPublisherAzure.cs

@@ -27,50 +27,6 @@ namespace NucuCar.Domain.Telemetry
             Logger?.LogDebug("Initialized the AzureTelemetryPublisher!");
         }
 
-        /// <summary>
-        /// Creates an instance of <see cref="TelemetryPublisher"/> that is used to publish data to Microsoft Azure.
-        /// </summary>
-        /// <param name="connectionString">The device connection string for Microsoft Azure IoT hub device.</param>
-        /// <returns>A <see cref="TelemetryPublisher"/> instance.</returns>
-        public static TelemetryPublisher CreateFromConnectionString(string connectionString)
-        {
-            Guard.ArgumentNotNullOrWhiteSpace(nameof(connectionString), connectionString);
-            return new TelemetryPublisherAzure(new TelemetryPublisherBuilderOptions()
-                {ConnectionString = connectionString, TelemetrySource = "TelemetryPublisherAzure"});
-        }
-
-        /// <summary>
-        /// Creates an instance of <see cref="TelemetryPublisher"/> that is used to publish data to Microsoft Azure.
-        /// </summary>
-        /// <param name="connectionString">Device connection string for Microsoft Azure IoT hub device.</param>
-        /// <param name="telemetrySource">String that is used to identify the source of the telemetry data.</param>
-        /// <returns>A <see cref="TelemetryPublisher"/> instance.</returns>
-        public static TelemetryPublisher CreateFromConnectionString(string connectionString,
-            string telemetrySource)
-        {
-            Guard.ArgumentNotNullOrWhiteSpace(nameof(connectionString), connectionString);
-            Guard.ArgumentNotNullOrWhiteSpace(nameof(telemetrySource), telemetrySource);
-            return new TelemetryPublisherAzure(new TelemetryPublisherBuilderOptions()
-                {ConnectionString = connectionString, TelemetrySource = telemetrySource});
-        }
-
-        /// <summary>
-        /// Creates an instance of <see cref="TelemetryPublisher"/> that is used to publish data to Microsoft Azure.
-        /// </summary>
-        /// <param name="connectionString">Device connection string for Microsoft Azure IoT hub device.</param>
-        /// <param name="telemetrySource">String that is used to identify the source of the telemetry data.</param>
-        /// <param name="logger">An <see cref="ILogger"/> logger instance. </param>
-        /// <returns>A <see cref="TelemetryPublisher"/> instance.</returns>
-        public static TelemetryPublisher CreateFromConnectionString(string connectionString,
-            string telemetrySource, ILogger logger)
-        {
-            Guard.ArgumentNotNullOrWhiteSpace(nameof(connectionString), connectionString);
-            Guard.ArgumentNotNullOrWhiteSpace(nameof(telemetrySource), telemetrySource);
-            Guard.ArgumentNotNull(nameof(logger), logger);
-            return new TelemetryPublisherAzure(new TelemetryPublisherBuilderOptions()
-                {ConnectionString = connectionString, TelemetrySource = telemetrySource, Logger = logger});
-        }
-
         public override async Task PublishAsync(CancellationToken cancellationToken)
         {
             var data = GetTelemetry();

NucuCar.Domain/Telemetry/TelemetryPublisherFactory.cs

@@ -0,0 +1,54 @@
+using System;
+using Microsoft.Extensions.Logging;
+
+namespace NucuCar.Domain.Telemetry
+{
+    /// <summary>
+    /// The TelemetryPublisherFactory is used instantiate TelemetryPublishers.
+    /// </summary>
+    public static class TelemetryPublisherFactory
+    {
+        /// <summary>
+        /// Creates an instance of <see cref="TelemetryPublisher"/>. See <see cref="TelemetryPublisherType"/>
+        /// </summary>
+        /// <param name="type">The type of the publisher. <see cref="TelemetryPublisherType"/> </param>
+        /// <param name="connectionString">Device connection string for Microsoft Azure IoT hub device.</param>
+        /// <param name="telemetrySource">String that is used to identify the source of the telemetry data.</param>
+        /// <param name="logger">An <see cref="ILogger"/> logger instance. </param>
+        /// <returns>A <see cref="TelemetryPublisher"/> instance.</returns>
+        public static TelemetryPublisher Create(string type, string connectionString,
+            string telemetrySource, ILogger logger)
+        {
+            Guard.ArgumentNotNullOrWhiteSpace(nameof(connectionString), connectionString);
+            Guard.ArgumentNotNullOrWhiteSpace(nameof(telemetrySource), telemetrySource);
+            Guard.ArgumentNotNull(nameof(logger), logger);
+            var opts = new TelemetryPublisherBuilderOptions()
+                {ConnectionString = connectionString, TelemetrySource = telemetrySource, Logger = logger};
+            return SpawnPublisher(type, opts);
+        }
+
+        /// <summary>
+        /// Creates an instance of <see cref="TelemetryPublisher"/>.
+        /// </summary>
+        /// <param name="type">The type of the publisher. See <see cref="TelemetryPublisherType"/> </param>
+        /// <param name="connectionString">The device connection string for the selected publisher.</param>
+        /// <returns>A <see cref="TelemetryPublisher"/> instance.</returns>
+        public static TelemetryPublisher CreateFromConnectionString(string type, string connectionString)
+        {
+            Guard.ArgumentNotNullOrWhiteSpace(nameof(connectionString), connectionString);
+            var opts = new TelemetryPublisherBuilderOptions()
+                {ConnectionString = connectionString, TelemetrySource = "TelemetryPublisherAzure"};
+            return SpawnPublisher(type, opts);
+        }
+
+        private static TelemetryPublisher SpawnPublisher(string type, TelemetryPublisherBuilderOptions opts)
+        {
+            return type switch
+            {
+                TelemetryPublisherType.Azure => (TelemetryPublisher) new TelemetryPublisherAzure(opts),
+                TelemetryPublisherType.Disk => new TelemetryPublisherDisk(opts),
+                _ => throw new ArgumentException($"Invalid TelemetryPublisher type: {type}.")
+            };
+        }
+    }
+}

NucuCar.Domain/Telemetry/TelemetryPublisherType.cs

@@ -0,0 +1,12 @@
+namespace NucuCar.Domain.Telemetry
+{
+    /// <summary>
+    /// TelemetryPublisherType holds constants for instantiating <see cref="TelemetryPublisher"/>,
+    /// see <see cref="TelemetryPublisherFactory"/>.
+    /// </summary>
+    public static class TelemetryPublisherType
+    {
+        public const string Azure = "Azure";
+        public const string Disk = "Disk";
+    }
+}

NucuCar.Sensors/Telemetry/SensorTelemetry.cs

@@ -1,6 +1,7 @@
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Options;
 using NucuCar.Domain.Telemetry;
+
 // ReSharper disable ClassWithVirtualMembersNeverInherited.Global
 
 namespace NucuCar.Sensors.Telemetry
@@ -11,14 +12,13 @@ namespace NucuCar.Sensors.Telemetry
 
         public SensorTelemetry()
         {
-            
         }
 
         public SensorTelemetry(ILogger<SensorTelemetry> logger, IOptions<TelemetryConfig> options)
         {
             if (options.Value.ServiceEnabled)
             {
-                Publisher = TelemetryPublisherAzure.CreateFromConnectionString(options.Value.ConnectionString,
+                Publisher = TelemetryPublisherFactory.Create(options.Value.Publisher, options.Value.ConnectionString,
                     "NucuCar.Sensors", logger);
             }
             else

NucuCar.Sensors/Telemetry/TelemetryConfig.cs

@@ -1,9 +1,17 @@
 // ReSharper disable UnusedAutoPropertyAccessor.Global
 
+using NucuCar.Domain.Telemetry;
+
 namespace NucuCar.Sensors.Telemetry
 {
     public class TelemetryConfig
     {
+        /// <summary>
+        ///  The Publisher is used by <see cref="TelemetryPublisherFactory"/> to instantiate
+        /// the correct <see cref="TelemetryPublisher"/>. For available types see <see cref="TelemetryPublisherType"/>
+        /// </summary>
+        public string Publisher { get; set; }
+
         public bool ServiceEnabled { get; set; }
         public int PublishInterval { get; set; }
         public string ConnectionString { get; set; }

NucuCar.Sensors/appsettings.json

@@ -1,5 +1,6 @@
 {
   "Telemetry": {
+    "Publisher": "Azure",
     "ServiceEnabled": true,
     "PublishInterval": 3000,
     "ConnectionString": "YOUR_CONNECTION_STRING"

NucuCar.TestClient/Telemetry/AzureTelemetryPublishCmd.cs

@@ -48,9 +48,8 @@ namespace NucuCar.TestClient.Telemetry
             var logger = LoggerFactory.Create(builder => { builder.AddConsole(); })
                 .CreateLogger<AzureTelemetryPublishCmd>();
 
-            var telemetryPublisher =
+            var telemetryPublisher = TelemetryPublisherFactory.Create(TelemetryPublisherType.Azure,
-                TelemetryPublisherAzure.CreateFromConnectionString(opts.PublisherConnectionString,
+                opts.PublisherConnectionString, "NucuCar.TestClient", logger);
-                    "NucuCar.TestClient", logger);
             
             var anonymousTelemeter =
                 new DummyTelemeter(

NucuCar.UnitTests/NucuCar.Domain.Tests/Telemetry/TelemetryPublisherFactoryTest.cs

@@ -0,0 +1,38 @@
+using System;
+using NucuCar.Domain.Telemetry;
+using Xunit;
+
+namespace NucuCar.UnitTests.NucuCar.Domain.Tests.Telemetry
+{
+    public class TelemetryPublisherFactoryTest
+    {
+        [Fact]
+        private void Test_Build_TelemetryPublisherAzure()
+        {
+            const string connectionString =
+                "HostName=something.azure-devices.net;DeviceId=something;SharedAccessKey=test";
+            var telemetryPublisher =
+                TelemetryPublisherFactory.CreateFromConnectionString(TelemetryPublisherType.Azure, connectionString);
+            Assert.IsType<TelemetryPublisherAzure>(telemetryPublisher);
+        }
+        
+        [Fact]
+        private void Test_Build_TelemetryPublisherDisk()
+        {
+            const string connectionString =
+                "Filename=test;BufferSize=4096";
+            var telemetryPublisher =
+                TelemetryPublisherFactory.CreateFromConnectionString(TelemetryPublisherType.Disk, connectionString);
+            Assert.IsType<TelemetryPublisherDisk>(telemetryPublisher);
+        }
+
+        [Fact]
+        private void Test_Build_ThrowsOnInvalidType()
+        {
+            Assert.Throws<ArgumentException>(() =>
+            {
+                TelemetryPublisherFactory.CreateFromConnectionString("_1", "a=b");
+            });
+        }
+    }
+}