Add client invocation for RestHublifetimeManager

src/Microsoft.Azure.SignalR.Common/Utilities/Rest/JsonPayloadContentBuilder.cs

@@ -24,4 +24,6 @@ public JsonPayloadContentBuilder(ObjectSerializer jsonObjectSerializer)
     {
         return payload == null ? null : new JsonPayloadMessageContent(payload, _jsonObjectSerializer, typeHint);
     }
+
+    public ObjectSerializer ObjectSerializer => _jsonObjectSerializer;
 }

src/Microsoft.Azure.SignalR.Common/Utilities/RestClient.cs

@@ -30,7 +30,7 @@ public RestClient(IHttpClientFactory httpClientFactory, IPayloadContentBuilder c
         _httpClientFactory = httpClientFactory;
         _payloadContentBuilder = contentBuilder;
     }
-    
+
     // TODO: Test only, will remove later
     internal RestClient(IHttpClientFactory httpClientFactory) : this(httpClientFactory, new JsonPayloadContentBuilder(new JsonObjectSerializer()))
     {
@@ -78,6 +78,17 @@ public Task SendMessageWithRetryAsync(
         return SendAsyncCore(Constants.HttpClientNames.MessageResilient, api, httpMethod, new InvocationMessage(methodName, args), null, AsAsync(handleExpectedResponse), cancellationToken);
     }
 
+    public Task SendMessageWithRetryAsync(
+        RestApiEndpoint api,
+        HttpMethod httpMethod,
+        string methodName,
+        object?[] args,
+        Func<HttpResponseMessage, Task<bool>>? handleExpectedResponseAsync = null,
+        CancellationToken cancellationToken = default)
+    {
+        return SendAsyncCore(Constants.HttpClientNames.MessageResilient, api, httpMethod, new InvocationMessage(methodName, args), null, handleExpectedResponseAsync, cancellationToken);
+    }
+
     public Task SendStreamMessageWithRetryAsync(
         RestApiEndpoint api,
         HttpMethod httpMethod,
@@ -90,6 +101,12 @@ public Task SendStreamMessageWithRetryAsync(
         return SendAsyncCore(Constants.HttpClientNames.MessageResilient, api, httpMethod, new StreamItemMessage(streamId, arg), typeHint, AsAsync(handleExpectedResponse), cancellationToken);
     }
 
+    public ObjectSerializer ObjectSerializer => _payloadContentBuilder switch
+    {
+        JsonPayloadContentBuilder jsonBuilder => jsonBuilder.ObjectSerializer,
+        _ => throw new NotSupportedException("Only JsonPayloadContentBuilder is supported to get the ObjectSerializer.")
+    };
+
     private static Uri GetUri(string url, IDictionary<string, StringValues>? query)
     {
         if (query == null || query.Count == 0)

src/Microsoft.Azure.SignalR.Management/ClientInvocation/InvocationResponse.cs

@@ -0,0 +1,12 @@
+// Copyright (c) Microsoft. All rights reserved.
+// Licensed under the MIT license. See LICENSE file in the project root for full license information.
+
+using System.Text.Json.Serialization;
+
+namespace Microsoft.Azure.SignalR.Management.ClientInvocation;
+#nullable enable
+sealed class InvocationResponse<T>
+{
+    [JsonPropertyName("result")]
+    public T? Result { get; set; }
+}

src/Microsoft.Azure.SignalR.Management/HubInstanceFactories/ServiceHubLifetimeManagerFactory.cs

@@ -5,7 +5,6 @@
 using System.ComponentModel;
 using System.Linq;
 using System.Net.Http;
-
 using Microsoft.AspNetCore.SignalR;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;

src/Microsoft.Azure.SignalR.Management/RestApiProvider.cs

@@ -108,4 +108,9 @@ private RestApiEndpoint GenerateRestApiEndpoint(string appName, string hubName,
             : $"{pathAfterHub}?application={Uri.EscapeDataString(appName.ToLowerInvariant())}&api-version={Version}";
         return new RestApiEndpoint($"{requestPrefixWithHub}{pathAfterHub}") { Query = queries };
     }
+
+     public RestApiEndpoint SendClientInvocation(string appName, string hubName, string connectionId)
+    {
+        return GenerateRestApiEndpoint(appName, hubName, $"/connections/{Uri.EscapeDataString(connectionId)}/:invoke");
+    }
 }

src/Microsoft.Azure.SignalR.Management/RestHubLifetimeManager.cs

@@ -7,12 +7,18 @@
 using System.Linq;
 using System.Net;
 using System.Net.Http;
+#if NET7_0_OR_GREATER
+using System.IO;
+#endif
 using System.Threading;
 using System.Threading.Tasks;
 
 using Azure;
-
 using Microsoft.AspNetCore.SignalR;
+#if NET7_0_OR_GREATER
+using Microsoft.AspNetCore.SignalR.Protocol;
+using Microsoft.Azure.SignalR.Management.ClientInvocation;
+#endif
 using Microsoft.Azure.SignalR.Protocol;
 using Microsoft.Extensions.Primitives;
 
@@ -351,6 +357,73 @@ public async Task SendStreamCompletionAsync(string connectionId, string streamId
         await _restClient.SendWithRetryAsync(api, HttpMethod.Post, cancellationToken: cancellationToken);
     }
 
+#if NET7_0_OR_GREATER
+#nullable enable
+    public override async Task<T> InvokeConnectionAsync<T>(string connectionId, string methodName, object?[] args, CancellationToken cancellationToken = default)
+    {
+        // Validate input parameters
+        if (string.IsNullOrEmpty(methodName))
+        {
+            throw new ArgumentException(NullOrEmptyStringErrorMessage, nameof(methodName));
+        }
+        if (string.IsNullOrEmpty(connectionId))
+        {
+            throw new ArgumentException(NullOrEmptyStringErrorMessage, nameof(connectionId));
+        }
+
+        // Get API endpoint and prepare for the request
+        var api = _restApiProvider.SendClientInvocation(_appName, _hubName, connectionId);
+        InvocationResponse<T>? wrapper = null;
+        string? errorContent = null;
+        bool isSuccess = false;
+        // Send request and capture the response
+        await _restClient.SendMessageWithRetryAsync(
+            api,
+            HttpMethod.Post,
+            methodName,
+            args,
+            async response =>
+            {
+                isSuccess = response.IsSuccessStatusCode;
+
+                if (isSuccess)
+                {
+                    await using var contentStream = await response.Content.ReadAsStreamAsync(cancellationToken);
+
+                    var deserialized = await _restClient.ObjectSerializer.DeserializeAsync(
+                        contentStream,
+                        typeof(InvocationResponse<T>),
+                        cancellationToken);
+
+                    wrapper = deserialized as InvocationResponse<T>
+                        ?? throw new HubException("Failed to deserialize response");
+                }
+                else
+                {
+                    errorContent = await response.Content.ReadAsStringAsync(cancellationToken);
+                }
+
+                return isSuccess || response.StatusCode == HttpStatusCode.BadRequest;
+            },
+            cancellationToken);
+
+        // Ensure we have a response
+        if (!isSuccess)
+        {
+            throw new HubException(errorContent ?? "Unknown error in response");
+        }
+
+        return wrapper != null && wrapper.Result != null ? wrapper.Result : throw new HubException("Result not found in response");
+    }
+
+    public override Task SetConnectionResultAsync(string connectionId, CompletionMessage result)
+    {
+        // This method won't get trigger because in transient we will wait for the returned completion message.
+        // this is to honor the interface
+        throw new NotImplementedException();
+    }
+#endif
+
     private static bool FilterExpectedResponse(HttpResponseMessage response, string expectedErrorCode) =>
         response.IsSuccessStatusCode
         || (response.StatusCode == HttpStatusCode.NotFound && response.Headers.TryGetValues(Headers.MicrosoftErrorCode, out var errorCodes) && errorCodes.First().Equals(expectedErrorCode, StringComparison.OrdinalIgnoreCase));