feat(fdc3):Load AppDirectory from web or FDC3 AppD API

src/fdc3/dotnet/AppDirectory/AppDirectory.sln

@@ -13,6 +13,8 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "lib", "lib", "{62C29BA4-0D3
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "MorganStanley.ComposeUI.Testing", "..\..\..\shared\dotnet\MorganStanley.ComposeUI.Testing\MorganStanley.ComposeUI.Testing.csproj", "{08AEA9CD-1DA8-4A73-BB10-90B0EF0EE8DC}"
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "test", "test", "{976748F5-4871-48F4-8AE0-99ABFB733D29}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -37,7 +39,7 @@ Global
 	EndGlobalSection
 	GlobalSection(NestedProjects) = preSolution
 		{4B8CA047-2023-4E1A-BD73-85F7EB1D56B3} = {9E52D00C-AABB-4579-8724-6CC7049F021E}
-		{EAA7B5A8-FD08-4E2F-809B-6CBD489714C1} = {9E52D00C-AABB-4579-8724-6CC7049F021E}
+		{EAA7B5A8-FD08-4E2F-809B-6CBD489714C1} = {976748F5-4871-48F4-8AE0-99ABFB733D29}
 		{08AEA9CD-1DA8-4A73-BB10-90B0EF0EE8DC} = {62C29BA4-0D3B-4764-A898-38F29FF5C36C}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution

src/fdc3/dotnet/AppDirectory/src/AppDirectory/AppDirectory.cs

@@ -28,10 +28,12 @@ public class AppDirectory : IAppDirectory
 {
     public AppDirectory(
         IOptions<AppDirectoryOptions> options,
+        IHttpClientFactory? httpClientFactory = null,
         IMemoryCache? cache = null,
         IFileSystem? fileSystem = null,
         ILogger<AppDirectory>? logger = null)
     {
+        _httpClientFactory = httpClientFactory;
         _options = options.Value;
         _cache = cache ?? new MemoryCache(new MemoryCacheOptions());
         _fileSystem = fileSystem ?? new FileSystem();
@@ -51,6 +53,8 @@ public async Task<IEnumerable<Fdc3App>> GetApps()
         return app;
     }
 
+    private readonly IHttpClientFactory? _httpClientFactory;
+    private HttpClient? _httpClient;
     private readonly IFileSystem _fileSystem;
     private readonly ILogger<AppDirectory> _logger;
     private readonly AppDirectoryOptions _options;
@@ -65,7 +69,14 @@ private Task<Dictionary<string, Fdc3App>> GetAppsCore()
             async entry =>
             {
                 var result = await LoadApps();
-                entry.ExpirationTokens.Add(result.ChangeToken);
+                if (result.ChangeToken != null)
+                {
+                    entry.ExpirationTokens.Add(result.ChangeToken);
+                }
+                else
+                {
+                    entry.AbsoluteExpirationRelativeToNow = TimeSpan.FromSeconds(_options.CacheExpirationInSeconds);
+                }
 
                 // Assuming that appIds are case-insensitive (not specified by the standard)
                 return result.Apps.ToDictionary(
@@ -74,39 +85,82 @@ private Task<Dictionary<string, Fdc3App>> GetAppsCore()
             });
     }
 
-    private Task<(IEnumerable<Fdc3App> Apps, IChangeToken ChangeToken)> LoadApps()
+    private Task<(IEnumerable<Fdc3App> Apps, IChangeToken? ChangeToken)> LoadApps()
     {
-        if (_fileSystem.File.Exists(_options.Source?.LocalPath))
+        if (_options.Source != null)
         {
-            return LoadAppsFromFile(_options.Source.LocalPath);
+            if (_options.Source.IsFile && _fileSystem.File.Exists(_options.Source.LocalPath))
+            {
+                return LoadAppsFromFile(_options.Source.LocalPath);
+            }
+
+            if (_options.Source.Scheme == Uri.UriSchemeHttp || _options.Source.Scheme == Uri.UriSchemeHttps)
+            {
+                return LoadAppsFromHttp(_options.Source.ToString());
+            }
+        }
+
+        if (!string.IsNullOrEmpty(_options.HttpClientName))
+        {
+            return LoadAppsFromHttp("apps/");
         }
-        // TODO: add provider for online static files and FDC3 AppD API
 
-        _logger.LogWarning("The configured source is empty or not supported");
+        _logger.LogError("The configured source is empty or not supported");
 
-        return Task.FromResult<(IEnumerable<Fdc3App>, IChangeToken)>(
+        return Task.FromResult<(IEnumerable<Fdc3App>, IChangeToken?)>(
             (
                 Enumerable.Empty<Fdc3App>(),
-                NullChangeToken.Singleton));
+                null));
     }
 
-    private Task<(IEnumerable<Fdc3App>, IChangeToken)> LoadAppsFromFile(string fileName)
+    private Task<(IEnumerable<Fdc3App>, IChangeToken?)> LoadAppsFromFile(string fileName)
     {
         using var stream = _fileSystem.File.OpenRead(fileName);
 
-        return Task.FromResult<(IEnumerable<Fdc3App>, IChangeToken)>(
+        return Task.FromResult<(IEnumerable<Fdc3App>, IChangeToken?)>(
             (
                 LoadAppsFromStream(stream),
                 new FileSystemChangeToken(fileName, _fileSystem)));
     }
 
+    private async Task<(IEnumerable<Fdc3App>, IChangeToken?)> LoadAppsFromHttp(string relativeUri)
+    {
+        var httpClient = GetHttpClient();
+        var response = await httpClient.GetAsync(relativeUri);
+        var stream = await response.Content.ReadAsStreamAsync();
+
+        return (LoadAppsFromStream(stream), null);
+    }
+
+    private HttpClient GetHttpClient()
+    {
+        if (_httpClient != null)
+            return _httpClient;
+
+        if (!string.IsNullOrEmpty(_options.HttpClientName))
+        {
+            // Let configuration changes propagate. The factory manages the lifetime of underlying resources.
+            return _httpClientFactory?.CreateClient(_options.HttpClientName)
+                   ?? throw new InvalidOperationException(
+                       $"{nameof(AppDirectoryOptions)} is configured with {nameof(AppDirectoryOptions.HttpClientName)}, but a suitable {nameof(IHttpClientFactory)} was not provided");
+        }
+
+        if (_httpClientFactory != null)
+            return _httpClientFactory.CreateClient();
+
+        return _httpClient = new HttpClient();
+    }
+
     private static IEnumerable<Fdc3App> LoadAppsFromStream(Stream stream)
     {
         var serializer = JsonSerializer.Create(new Fdc3JsonSerializerSettings());
         using var textReader = new StreamReader(stream, leaveOpen: true);
         using var jsonReader = new JsonTextReader(textReader);
+        jsonReader.Read();
 
-        return serializer.Deserialize<IEnumerable<Fdc3App>>(jsonReader) ?? Enumerable.Empty<Fdc3App>();
+        return jsonReader.TokenType == JsonToken.StartArray
+            ? serializer.Deserialize<IEnumerable<Fdc3App>>(jsonReader) ?? Enumerable.Empty<Fdc3App>()
+            : serializer.Deserialize<GetAppsJsonResponse>(jsonReader)?.Applications ?? Enumerable.Empty<Fdc3App>();
     }
 
     private sealed class FileSystemChangeToken : IChangeToken
@@ -158,16 +212,12 @@ public IDisposable RegisterChangeCallback(Action<object> callback, object state)
         private readonly ConcurrentDictionary<object, Action> _callbacks = new();
     }
 
-    private sealed class NullChangeToken : IChangeToken
+    /// <summary>
+    /// Wrapper type for the /v2/apps response
+    /// </summary>
+    private sealed class GetAppsJsonResponse
     {
-        public bool HasChanged => false;
-        public bool ActiveChangeCallbacks => true;
-
-        public IDisposable RegisterChangeCallback(Action<object> callback, object state)
-        {
-            return Disposable.Empty;
-        }
-
-        public static readonly NullChangeToken Singleton = new();
+        [JsonProperty("applications")]
+        public IEnumerable<Fdc3App>? Applications { get; set; }
     }
 }

src/fdc3/dotnet/AppDirectory/src/AppDirectory/AppDirectory.csproj

@@ -11,6 +11,7 @@
 	<ItemGroup>
 		<PackageReference Include="Microsoft.Extensions.Caching.Memory" Version="6.0.1" />
 		<PackageReference Include="Microsoft.Extensions.DependencyInjection.Abstractions" Version="6.0.0" />
+		<PackageReference Include="Microsoft.Extensions.Http" Version="6.0.0" />
 		<PackageReference Include="Microsoft.Extensions.Options" Version="6.0.0" />
 		<PackageReference Include="MorganStanley.Fdc3.AppDirectory" Version="2.0.0-alpha.6" />
 		<PackageReference Include="MorganStanley.Fdc3.NewtonsoftJson" Version="2.0.0-alpha.6" />

src/fdc3/dotnet/AppDirectory/src/AppDirectory/AppDirectoryOptions.cs

@@ -26,24 +26,33 @@ public sealed class AppDirectoryOptions : IOptions<AppDirectoryOptions>
     /// <remarks>
     ///     Supported schemes are <c>file</c>, <c>http</c> and <c>https</c>.
     ///     The static file must contain a single array of <see cref="Fdc3App" /> objects,
-    ///     using the schema defined by the FDC3 AppDirectory API specification
-    ///     (https://fdc3.finos.org/schemas/2.0/app-directory.html#tag/Application/paths/~1v2~1apps~1%7BappId%7D/get)
+    ///     or the response object defined in the FDC3 AppDirectory REST API specification
+    ///     for getting all apps(https://fdc3.finos.org/schemas/2.0/app-directory.html#tag/Application/paths/~1v2~1apps/get).
     ///     UTF8 encoding is assumed unless a byte order mark or encoding header is present.
     /// </remarks>
     public Uri? Source { get; set; }
 
-    // TODO: Implement fetching from AppD REST API
-    ///// <summary>
-    ///// Gets or sets the name of the <see cref="HttpClient"/> that is used to fetch
-    ///// the application definitions from a REST API defined by the FDC3 AppDirectory API specification (https://fdc3.finos.org/schemas/2.0/app-directory.html)
-    ///// </summary>
-    ///// <remarks>
-    ///// This property is only used when <see cref="Source"/> is set to <c>null</c>.
-    ///// When this property is set, an <see cref="IHttpClientFactory"/> instance must be provided as a constructor parameter
-    ///// for <see cref="AppDirectory"/>, with a matching HTTP client configured.
-    ///// </remarks>
-    //public string? HttpClientName { get; set; }
+    /// <summary>
+    ///     Gets or sets the name of the <see cref="HttpClient" /> that is used to fetch
+    ///     the application definitions from a web URL or a REST API defined by the FDC3 AppDirectory API specification
+    ///     (https://fdc3.finos.org/schemas/2.0/app-directory.html)
+    /// </summary>
+    /// <remarks>
+    ///     When this property is set, an <see cref="IHttpClientFactory" /> instance must be provided as a constructor
+    ///     parameter for <see cref="AppDirectory" />, with a matching HTTP client configured.
+    /// </remarks>
+    public string? HttpClientName { get; set; }
+
+    /// <summary>
+    /// Gets or sets the cache expiration time in seconds. This value is ignored when loading the apps from a local file.
+    /// </summary>
+    public int CacheExpirationInSeconds { get; set; } = (int)DefaultCacheExpiration.TotalSeconds;
 
     /// <inheritdoc />
     public AppDirectoryOptions Value => this;
+
+    /// <summary>
+    /// Gets the default cache expiration time
+    /// </summary>
+    public static readonly TimeSpan DefaultCacheExpiration = TimeSpan.FromHours(1);
 }