Fdc3 - Enable Fdc3 as an optional feature

src/fdc3/Directory.Build.props

@@ -0,0 +1,3 @@
+<Project>
+	<Import Project="../Directory.Build.props" Condition="Exists('../Directory.Build.props')" />
+</Project>

src/fdc3/dotnet/DesktopAgent/src/DesktopAgent/DependencyInjection/Fdc3DesktopAgentBuilder.cs

@@ -0,0 +1,56 @@
+/*
+ * Morgan Stanley makes this available to you under the Apache License,
+ * Version 2.0 (the "License"). You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0.
+ *
+ * See the NOTICE file distributed with this work for additional information
+ * regarding copyright ownership. 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.
+ */
+
+using Microsoft.Extensions.Configuration;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Options;
+
+namespace MorganStanley.ComposeUI.Fdc3.DesktopAgent.DependencyInjection;
+
+public class Fdc3DesktopAgentBuilder
+{
+    public IServiceCollection ServiceCollection { get; }
+
+    public Fdc3DesktopAgentBuilder(IServiceCollection serviceCollection)
+    {
+        ServiceCollection = serviceCollection;
+    }
+
+    /// <summary>
+    /// Method, for configuring `Fdc3Options` from full `IConfiguration` by searching for section `Fdc3Options.Fdc3OptionsName`.
+    /// </summary>
+    /// <typeparam name="TOptions">Must be Fdc3Options reference type.</typeparam>
+    /// <param name="configuration">Full IConfigration passed from the Application.</param>
+    /// <returns></returns>
+    public Fdc3DesktopAgentBuilder Configure<TOptions>(IConfiguration configuration) 
+        where TOptions : class, IOptions<Fdc3Options>
+    {
+        ServiceCollection.Configure<TOptions>(configuration.GetSection(Fdc3Options.Fdc3OptionsName));
+
+        return this;
+    }
+
+    /// <summary>
+    /// Extension method, for configuring the `Fdc3Options` by `Action`.
+    /// </summary>
+    /// <param name="configureOptions"></param>
+    /// <returns></returns>
+    public Fdc3DesktopAgentBuilder Configure(Action<Fdc3Options> configureOptions)
+    {
+        ServiceCollection.AddOptions<Fdc3Options>()
+            .Configure(configureOptions);
+
+        return this;
+    }
+}

src/fdc3/dotnet/DesktopAgent/src/DesktopAgent/DependencyInjection/Fdc3DesktopAgentConfig.cs → src/fdc3/dotnet/DesktopAgent/src/DesktopAgent/DependencyInjection/Fdc3Options.cs

@@ -12,15 +12,23 @@
  * and limitations under the License.
  */
 
+using Microsoft.Extensions.Options;
+
 namespace MorganStanley.ComposeUI.Fdc3.DesktopAgent.DependencyInjection;
 
-public class Fdc3DesktopAgentConfig
+public sealed class Fdc3Options : IOptions<Fdc3Options>
 {
-    internal List<Func<Fdc3DesktopAgent, ValueTask>> BuilderActions { get; } = new();
+    public static readonly string Fdc3OptionsName = "Fdc3Options";
+
+    /// <summary>
+    /// When set to <value>true</value>, it will enable Fdc3 backend service.
+    /// </summary>
+    public bool EnableFdc3 { get; set; }
+
+    /// <summary>
+    /// When set to any value, it will start the DesktopAgent with passing the value to the `WithUserChannel` builder action.
+    /// </summary>
+    public string? ChannelId { get; set; }
 
-    public Fdc3DesktopAgentConfig WithUserChannel(string channelId)
-    {
-        BuilderActions.Add(fdc3 => fdc3.AddUserChannel(channelId));
-        return this;
-    }
+    Fdc3Options IOptions<Fdc3Options>.Value => this;
 }

src/fdc3/dotnet/DesktopAgent/src/DesktopAgent/DependencyInjection/ServiceCollectionExtensions.cs

@@ -12,6 +12,7 @@
  * and limitations under the License.
  */
 
+using Microsoft.Extensions.Configuration;
 using Microsoft.Extensions.Hosting;
 using MorganStanley.ComposeUI.Fdc3.DesktopAgent;
 using MorganStanley.ComposeUI.Fdc3.DesktopAgent.DependencyInjection;
@@ -22,15 +23,41 @@ public static class ServiceCollectionExtensions
 {
     public static IServiceCollection AddFdc3DesktopAgent(
         this IServiceCollection serviceCollection,
-        Action<Fdc3DesktopAgentConfig>? builderAction = null)
+        Action<Fdc3DesktopAgentBuilder>? builderAction = null)
     {
-        var config = new Fdc3DesktopAgentConfig();
+        var builder = new Fdc3DesktopAgentBuilder(serviceCollection);
+
         if (builderAction != null)
         {
-            builderAction(config);
+            builderAction(builder);
         }
-        serviceCollection.AddSingleton(config);
+
         serviceCollection.AddSingleton<IHostedService, Fdc3DesktopAgent>();
         return serviceCollection;
     }
+
+    /// <summary>
+    /// Checks the configuration, if that contains Fdc3Options part, where the user could set the EnableFdc3 tag to true.
+    /// If that tag value is true, it will add the DesktopAgent service to the ServiceCollection, with the given Fdc3Options, that was set in the configuration.
+    /// </summary>
+    /// <param name="serviceCollection"></param>
+    /// <param name="configuration">This should be the IConfigurationSection, which contains the configuration for Fdc3.</param>
+    /// <param name="builderAction"></param>
+    /// <returns></returns>
+    public static IServiceCollection InjectFdc3BackendServiceIfEnabledFromConfig(
+        this IServiceCollection serviceCollection,
+        IConfiguration configuration,
+        Action<Fdc3DesktopAgentBuilder>? builderAction = null)
+    {
+        var fdc3Options = configuration.Get<Fdc3Options>();
+
+        //TODO: This should be feature toggle, once we have feature toggles in the future - instead of having `EnableFdc3` inside Fdc3Options.
+        if (fdc3Options.EnableFdc3)
+        {
+            serviceCollection.Configure<Fdc3Options>(configuration);
+            serviceCollection.AddFdc3DesktopAgent(builderAction);
+        }
+
+        return serviceCollection;
+    }
 }

src/fdc3/dotnet/DesktopAgent/src/DesktopAgent/DesktopAgent.csproj

@@ -1,21 +1,21 @@
-<Project Sdk="Microsoft.NET.Sdk">
-  <PropertyGroup>
-    <TargetFramework>net6.0</TargetFramework>
-    <ImplicitUsings>enable</ImplicitUsings>
-    <Nullable>enable</Nullable>
-    <AssemblyName>MorganStanley.ComposeUI.Fdc3.$(MSBuildProjectName)</AssemblyName>
-    <RootNamespace>MorganStanley.ComposeUI.Fdc3.$(MSBuildProjectName.Replace(" ", "_"))</RootNamespace>
-  </PropertyGroup>
+<Project Sdk="Microsoft.NET.Sdk">
+	<PropertyGroup>
+		<TargetFramework>net6.0</TargetFramework>
+		<ImplicitUsings>enable</ImplicitUsings>
+		<Nullable>enable</Nullable>
+		<AssemblyName>MorganStanley.ComposeUI.Fdc3.$(MSBuildProjectName)</AssemblyName>
+		<RootNamespace>MorganStanley.ComposeUI.Fdc3.$(MSBuildProjectName.Replace(" ", "_"))</RootNamespace>
+	</PropertyGroup>
 
-  <ItemGroup>
-    <PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="6.0.0" />
-    <PackageReference Include="Microsoft.Extensions.Hosting" Version="6.0.1" />
-    <PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="6.0.4" />
-    <PackageReference Include="MorganStanley.Fdc3" Version="2.0.0-alpha.5" />
-  </ItemGroup>
+	<ItemGroup>
+		<PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="6.0.0" />
+		<PackageReference Include="Microsoft.Extensions.Hosting" Version="6.0.1" />
+		<PackageReference Include="Microsoft.Extensions.Logging.Abstractions" Version="6.0.4" />
+		<PackageReference Include="MorganStanley.Fdc3" Version="2.0.0-alpha.5" />
+	</ItemGroup>
 
-  <ItemGroup>
-    <ProjectReference Include="..\..\..\..\..\messaging\dotnet\src\Core\MorganStanley.ComposeUI.Messaging.Core.csproj" />
-  </ItemGroup>
+	<ItemGroup>
+		<ProjectReference Include="..\..\..\..\..\messaging\dotnet\src\Core\MorganStanley.ComposeUI.Messaging.Core.csproj" />
+	</ItemGroup>
 
 </Project>

src/fdc3/dotnet/DesktopAgent/src/DesktopAgent/Fdc3DesktopAgent.cs

@@ -15,6 +15,7 @@
 using Microsoft.Extensions.Hosting;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
+using Microsoft.Extensions.Options;
 using MorganStanley.ComposeUI.Fdc3.DesktopAgent.Contracts;
 using MorganStanley.ComposeUI.Fdc3.DesktopAgent.DependencyInjection;
 using MorganStanley.ComposeUI.Messaging;
@@ -27,14 +28,17 @@ public class Fdc3DesktopAgent : IHostedService
     private readonly List<UserChannel> _userChannels = new();
 
     private readonly ILoggerFactory _loggerFactory;
+    private readonly Fdc3Options _options;
     private readonly IMessageRouter _messageRouter;
-    private Fdc3DesktopAgentConfig? _config;
 
-    public Fdc3DesktopAgent(IMessageRouter messageRouter, ILoggerFactory? loggerFactory, Fdc3DesktopAgentConfig? config)
+    public Fdc3DesktopAgent(
+        IOptions<Fdc3Options> options, 
+        IMessageRouter messageRouter, 
+        ILoggerFactory? loggerFactory = null)
     {
+        _options = options.Value;
         _messageRouter = messageRouter;
         _loggerFactory = loggerFactory ?? NullLoggerFactory.Instance;
-        _config = config;
     }
 
     public async ValueTask AddUserChannel(string id)
@@ -61,19 +65,9 @@ public async Task StartAsync(CancellationToken cancellationToken)
     {
         await _messageRouter.RegisterServiceAsync(Fdc3Topic.FindChannel, FindChannel);
 
-        if (_config == null)
-        {
-            return;
-        }
-
-        // There are no dependencies among possible actions at the moment.
-        // Future features may introduce dependencies, in that case this solution needs to change
-        foreach (var task in _config.BuilderActions.Select(x => x(this)).ToArray())
-        {
-            await (task);
-        }
+        if (_options.ChannelId == null) return;
 
-        _config = null;        
+        await AddUserChannel(_options.ChannelId);
     }
 
     public async Task StopAsync(CancellationToken cancellationToken)