[Fusion] Support legacy HotChocolate batching protocol

src/HotChocolate/Fusion/benchmarks/Fusion.Execution.Benchmarks/GraphQLQueryBenchmark.cs

@@ -14,6 +14,8 @@
 using BenchmarkDotNet.Exporters.Csv;
 using BenchmarkDotNet.Exporters;
 using HotChocolate.Buffers;
+using HotChocolate.Fusion;
+using HotChocolate.Fusion.Execution;
 
 namespace Fusion.Execution.Benchmarks;
 
@@ -49,14 +51,28 @@ public async Task GlobalSetup()
         (_server, _app) = await GraphQLServerHelper.CreateTestServer();
         _client = _server.CreateClient();
 
-        var items = new HotChocolate.Transport.OperationRequest("{ items }");
-        var fewItems = new HotChocolate.Transport.OperationRequest("{ fewItems }");
-
+        var fusionItems = new HotChocolate.Fusion.Transport.OperationRequest(
+            "{ items }",
+            id: null,
+            operationName: null,
+            onError: null,
+            variables: VariableValues.Empty,
+            extensions: JsonSegment.Empty);
+        var fusionFewItems = new HotChocolate.Fusion.Transport.OperationRequest(
+            "{ fewItems }",
+            id: null,
+            operationName: null,
+            onError: null,
+            variables: VariableValues.Empty,
+            extensions: JsonSegment.Empty);
 
-        _fusionItemsRequest = new FusionGraphQLHttpRequest(items, _requestUri);
-        _fusionFewItemsRequest = new FusionGraphQLHttpRequest(fewItems, _requestUri);
+        _fusionItemsRequest = new FusionGraphQLHttpRequest(fusionItems, _requestUri);
+        _fusionFewItemsRequest = new FusionGraphQLHttpRequest(fusionFewItems, _requestUri);
         _fusionClient = new FusionClient(_client);
 
+        var items = new HotChocolate.Transport.OperationRequest("{ items }");
+        var fewItems = new HotChocolate.Transport.OperationRequest("{ fewItems }");
+
         _transportItemsRequest = new TransportGraphQLHttpRequest(items, _requestUri);
         _transportFewItemsRequest = new TransportGraphQLHttpRequest(fewItems, _requestUri);
         _transportClient = new TransportClient(_client);

src/HotChocolate/Fusion/src/Fusion.Execution/DependencyInjection/CoreFusionGatewayBuilderExtensions.SourceSchemaClients.cs

@@ -24,8 +24,8 @@ public static partial class CoreFusionGatewayBuilderExtensions
     /// <param name="supportedOperations">
     /// The supported operations.
     /// </param>
-    /// <param name="batchingMode">
-    /// The batching mode.
+    /// <param name="capabilities">
+    /// The client capabilities.
     /// </param>
     /// <param name="defaultAcceptHeaderValues">
     /// The <c>Accept</c> header values sent in case of a single, non-Subscription GraphQL request.
@@ -53,7 +53,7 @@ public static IFusionGatewayBuilder AddHttpClientConfiguration(
         string name,
         Uri baseAddress,
         SupportedOperationType supportedOperations = SupportedOperationType.All,
-        SourceSchemaHttpClientBatchingMode batchingMode = SourceSchemaHttpClientBatchingMode.VariableBatching,
+        SourceSchemaClientCapabilities? capabilities = null,
         ImmutableArray<MediaTypeWithQualityHeaderValue>? defaultAcceptHeaderValues = null,
         ImmutableArray<MediaTypeWithQualityHeaderValue>? batchingAcceptHeaderValues = null,
         ImmutableArray<MediaTypeWithQualityHeaderValue>? subscriptionAcceptHeaderValues = null,
@@ -66,7 +66,7 @@ public static IFusionGatewayBuilder AddHttpClientConfiguration(
             name,
             baseAddress,
             supportedOperations,
-            batchingMode,
+            capabilities,
             defaultAcceptHeaderValues,
             batchingAcceptHeaderValues,
             subscriptionAcceptHeaderValues,
@@ -92,8 +92,8 @@ public static IFusionGatewayBuilder AddHttpClientConfiguration(
     /// <param name="supportedOperations">
     /// The supported operations.
     /// </param>
-    /// <param name="batchingMode">
-    /// The batching mode.
+    /// <param name="capabilities">
+    /// The client capabilities.
     /// </param>
     /// <param name="defaultAcceptHeaderValues">
     /// The <c>Accept</c> header values sent in case of a single, non-Subscription GraphQL request.
@@ -122,7 +122,7 @@ public static IFusionGatewayBuilder AddHttpClientConfiguration(
         string httpClientName,
         Uri baseAddress,
         SupportedOperationType supportedOperations = SupportedOperationType.All,
-        SourceSchemaHttpClientBatchingMode batchingMode = SourceSchemaHttpClientBatchingMode.VariableBatching,
+        SourceSchemaClientCapabilities? capabilities = null,
         ImmutableArray<MediaTypeWithQualityHeaderValue>? defaultAcceptHeaderValues = null,
         ImmutableArray<MediaTypeWithQualityHeaderValue>? batchingAcceptHeaderValues = null,
         ImmutableArray<MediaTypeWithQualityHeaderValue>? subscriptionAcceptHeaderValues = null,
@@ -142,7 +142,7 @@ public static IFusionGatewayBuilder AddHttpClientConfiguration(
                 httpClientName,
                 baseAddress,
                 supportedOperations,
-                batchingMode,
+                capabilities,
                 defaultAcceptHeaderValues,
                 batchingAcceptHeaderValues,
                 subscriptionAcceptHeaderValues,

src/HotChocolate/Fusion/src/Fusion.Execution/Execution/Clients/SourceSchemaClientCapabilities.cs

@@ -8,28 +8,17 @@ namespace HotChocolate.Fusion.Execution.Clients;
 [Flags]
 public enum SourceSchemaClientCapabilities
 {
+    None = 0,
+
     /// <summary>
     /// The client supports variable batching, where a single request carries multiple
     /// sets of variables so the downstream service can resolve them in one round-trip.
     /// </summary>
-    VariableBatching = 1,
+    VariableBatching = 1 << 1,
 
     /// <summary>
     /// The client supports request batching, where multiple independent GraphQL
     /// operations are sent as an array in a single HTTP request.
     /// </summary>
-    RequestBatching = 2,
-
-    /// <summary>
-    /// The client supports the Apollo-style request batching format, which uses a
-    /// JSON array of operation objects as the request body.
-    /// </summary>
-    ApolloRequestBatching = 4,
-
-    /// <summary>
-    /// The client supports file upload via the
-    /// <see href="https://github.com/jaydenseric/graphql-multipart-request-spec">
-    /// GraphQL multipart request specification</see>.
-    /// </summary>
-    FileUpload = 8
+    RequestBatching = 1 << 2
 }