Plumbing TransferMode on the client side

src/Microsoft.AspNetCore.SignalR.Client/HubConnection.cs

@@ -11,6 +11,8 @@ using System.Threading.Tasks;
 using System.Threading.Tasks.Channels;
 using Microsoft.AspNetCore.SignalR.Internal;
 using Microsoft.AspNetCore.SignalR.Internal.Protocol;
+using Microsoft.AspNetCore.Sockets;
+using Microsoft.AspNetCore.Sockets.Features;
 using Microsoft.AspNetCore.Sockets.Client;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Abstractions;
@@ -77,6 +79,18 @@ namespace Microsoft.AspNetCore.SignalR.Client
 
         public async Task StartAsync()
         {
+            var transferModeFeature = _connection.Features.Get<ITransferModeFeature>();
+            if (transferModeFeature == null)
+            {
+                transferModeFeature = new TransferModeFeature();
+                _connection.Features.Set(transferModeFeature);
+            }
+
+            transferModeFeature.TransferMode =
+                (_protocol.Type == ProtocolType.Binary)
+                    ? TransferMode.Binary
+                    : TransferMode.Text;
+
             await _connection.StartAsync();
 
             using (var memoryStream = new MemoryStream())
@@ -389,5 +403,10 @@ namespace Microsoft.AspNetCore.SignalR.Client
                 ParameterTypes = parameterTypes;
             }
         }
+
+        private class TransferModeFeature : ITransferModeFeature
+        {
+            public TransferMode TransferMode { get; set; }
+        }
     }
 }

src/Microsoft.AspNetCore.SignalR.Common/Internal/Protocol/IHubProtocol.cs

@@ -11,6 +11,8 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Protocol
     {
         string Name { get; }
 
+        ProtocolType Type { get; }
+
         bool TryParseMessages(ReadOnlyBuffer<byte> input, IInvocationBinder binder, out IList<HubMessage> messages);
 
         void WriteMessage(HubMessage message, Stream output);

src/Microsoft.AspNetCore.SignalR.Common/Internal/Protocol/JsonHubProtocol.cs

@@ -46,6 +46,8 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Protocol
 
         public string Name => "json";
 
+        public ProtocolType Type => ProtocolType.Text;
+
         public bool TryParseMessages(ReadOnlyBuffer<byte> input, IInvocationBinder binder, out IList<HubMessage> messages)
         {
             messages = new List<HubMessage>();

src/Microsoft.AspNetCore.SignalR.Common/Internal/Protocol/MessagePackHubProtocol.cs

@@ -18,6 +18,8 @@ namespace Microsoft.AspNetCore.SignalR.Internal.Protocol
 
         public string Name => "messagepack";
 
+        public ProtocolType Type => ProtocolType.Binary;
+
         public bool TryParseMessages(ReadOnlyBuffer<byte> input, IInvocationBinder binder, out IList<HubMessage> messages)
         {
             messages = new List<HubMessage>();

src/Microsoft.AspNetCore.SignalR.Common/Internal/Protocol/ProtocolType.cs

@@ -0,0 +1,11 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.SignalR.Internal.Protocol
+{
+    public enum ProtocolType
+    {
+        Binary,
+        Text
+    }
+}

src/Microsoft.AspNetCore.Sockets.Abstractions/Features/IConnectionTransportFeature.cs

@@ -1,9 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-using System;
-using System.Collections.Generic;
-using System.Text;
 using System.Threading.Tasks.Channels;
 
 namespace Microsoft.AspNetCore.Sockets.Features

src/Microsoft.AspNetCore.Sockets.Abstractions/Features/ITransferModeFeature.cs

@@ -0,0 +1,10 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+namespace Microsoft.AspNetCore.Sockets.Features
+{
+    public interface ITransferModeFeature
+    {
+        TransferMode TransferMode { get; set; }
+    }
+}

src/Microsoft.AspNetCore.Sockets.Abstractions/IConnection.cs

@@ -4,6 +4,7 @@
 using System;
 using System.Threading;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http.Features;
 
 namespace Microsoft.AspNetCore.Sockets.Client
 {
@@ -16,5 +17,7 @@ namespace Microsoft.AspNetCore.Sockets.Client
         event Func<Task> Connected;
         event Func<byte[], Task> Received;
         event Func<Exception, Task> Closed;
+
+        IFeatureCollection Features { get; }
     }
 }

src/Microsoft.AspNetCore.Sockets.Abstractions/TransferMode.cs

@@ -0,0 +1,14 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+
+namespace Microsoft.AspNetCore.Sockets
+{
+    [Flags]
+    public enum TransferMode
+    {
+        Binary = 0x01,
+        Text = 0x02
+    }
+}

src/Microsoft.AspNetCore.Sockets.Client.Http/HttpConnection.cs

@@ -2,11 +2,14 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Diagnostics;
 using System.IO;
 using System.Net.Http;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Threading.Tasks.Channels;
+using Microsoft.AspNetCore.Http.Features;
+using Microsoft.AspNetCore.Sockets.Features;
 using Microsoft.AspNetCore.Sockets.Client.Internal;
 using Microsoft.AspNetCore.Sockets.Internal;
 using Microsoft.Extensions.Logging;
@@ -35,6 +38,8 @@ namespace Microsoft.AspNetCore.Sockets.Client
 
         public Uri Url { get; }
 
+        public IFeatureCollection Features { get; } = new FeatureCollection();
+
         public event Func<Task> Connected;
         public event Func<byte[], Task> Received;
         public event Func<Exception, Task> Closed;
@@ -48,7 +53,7 @@ namespace Microsoft.AspNetCore.Sockets.Client
         { }
 
         public HttpConnection(Uri url, TransportType transportType)
-                    : this(url, transportType, loggerFactory: null)
+            : this(url, transportType, loggerFactory: null)
         {
         }
 
@@ -262,7 +267,11 @@ namespace Microsoft.AspNetCore.Sockets.Client
             // Start the transport, giving it one end of the pipeline
             try
             {
-                await _transport.StartAsync(connectUrl, applicationSide, _connectionId);
+                await _transport.StartAsync(connectUrl, applicationSide, requestedTransferMode: GetTransferMode(), connectionId: _connectionId);
+
+                // actual transfer mode can differ from the one that was requested so set it on the feature
+                Debug.Assert(_transport.Mode.HasValue, "transfer mode not set after transport started");
+                SetTransferMode(_transport.Mode.Value);
             }
             catch (Exception ex)
             {
@@ -271,6 +280,29 @@ namespace Microsoft.AspNetCore.Sockets.Client
             }
         }
 
+        private TransferMode GetTransferMode()
+        {
+            var transferModeFeature = Features.Get<ITransferModeFeature>();
+            if (transferModeFeature == null)
+            {
+                return TransferMode.Text;
+            }
+
+            return transferModeFeature.TransferMode;
+        }
+
+        private void SetTransferMode(TransferMode transferMode)
+        {
+            var transferModeFeature = Features.Get<ITransferModeFeature>();
+            if (transferModeFeature == null)
+            {
+                transferModeFeature = new TransferModeFeature();
+                Features.Set(transferModeFeature);
+            }
+
+            transferModeFeature.TransferMode = transferMode;
+        }
+
         private async Task ReceiveAsync()
         {
             try

src/Microsoft.AspNetCore.Sockets.Client.Http/ITransport.cs

@@ -9,7 +9,8 @@ namespace Microsoft.AspNetCore.Sockets.Client
 {
     public interface ITransport
     {
-        Task StartAsync(Uri url, Channel<byte[], SendMessage> application, string connectionId);
+        Task StartAsync(Uri url, Channel<byte[], SendMessage> application, TransferMode requestedTransferMode, string connectionId);
         Task StopAsync();
+        TransferMode? Mode { get; }
     }
 }

src/Microsoft.AspNetCore.Sockets.Client.Http/Internal/SocketClientLoggerExtensions.cs

@@ -10,8 +10,8 @@ namespace Microsoft.AspNetCore.Sockets.Client.Internal
     internal static class SocketClientLoggerExtensions
     {
         // Category: Shared with LongPollingTransport, WebSocketsTransport and ServerSentEventsTransport
-        private static readonly Action<ILogger, DateTime, string, Exception> _startTransport =
+        private static readonly Action<ILogger, DateTime, string, TransferMode, Exception> _startTransport =
-            LoggerMessage.Define<DateTime, string>(LogLevel.Information, 0, "{time}: Connection Id {connectionId}: Starting transport.");
+            LoggerMessage.Define<DateTime, string, TransferMode>(LogLevel.Information, 0, "{time}: Connection Id {connectionId}: Starting transport. Transfer mode: {transferMode}.");
 
         private static readonly Action<ILogger, DateTime, string, Exception> _transportStopped =
             LoggerMessage.Define<DateTime, string>(LogLevel.Debug, 1, "{time}: Connection Id {connectionId}: Transport stopped.");
@@ -147,11 +147,11 @@ namespace Microsoft.AspNetCore.Sockets.Client.Internal
         private static readonly Action<ILogger, DateTime, string, Exception> _stoppingClient =
             LoggerMessage.Define<DateTime, string>(LogLevel.Information, 18, "{time}: Connection Id {connectionId}: Stopping client.");
 
-        public static void StartTransport(this ILogger logger, string connectionId)
+        public static void StartTransport(this ILogger logger, string connectionId, TransferMode transferMode)
         {
             if (logger.IsEnabled(LogLevel.Information))
             {
-                _startTransport(logger, DateTime.Now, connectionId, null);
+                _startTransport(logger, DateTime.Now, connectionId, transferMode, null);
             }
         }
 

src/Microsoft.AspNetCore.Sockets.Client.Http/LongPollingTransport.cs

@@ -26,6 +26,8 @@ namespace Microsoft.AspNetCore.Sockets.Client
 
         public Task Running { get; private set; } = Task.CompletedTask;
 
+        public TransferMode? Mode { get; private set; }
+
         public LongPollingTransport(HttpClient httpClient)
             : this(httpClient, null)
         { }
@@ -36,12 +38,18 @@ namespace Microsoft.AspNetCore.Sockets.Client
             _logger = (loggerFactory ?? NullLoggerFactory.Instance).CreateLogger<LongPollingTransport>();
         }
 
-        public Task StartAsync(Uri url, Channel<byte[], SendMessage> application, string connectionId)
+        public Task StartAsync(Uri url, Channel<byte[], SendMessage> application, TransferMode requestedTransferMode, string connectionId)
         {
-            _connectionId = connectionId;
+            if (requestedTransferMode != TransferMode.Binary && requestedTransferMode != TransferMode.Text)
-            _logger.StartTransport(_connectionId);
+            {
+                throw new ArgumentException("Invalid transfer mode.", nameof(requestedTransferMode));
+            }
 
             _application = application;
+            Mode = requestedTransferMode;
+            _connectionId = connectionId;
+
+            _logger.StartTransport(_connectionId, Mode.Value);
 
             // Start sending and polling (ask for binary if the server supports it)
             _poller = Poll(url, _transportCts.Token);

src/Microsoft.AspNetCore.Sockets.Client.Http/ServerSentEventsTransport.cs

@@ -27,6 +27,8 @@ namespace Microsoft.AspNetCore.Sockets.Client
 
         public Task Running { get; private set; } = Task.CompletedTask;
 
+        public TransferMode? Mode { get; private set; }
+
         public ServerSentEventsTransport(HttpClient httpClient)
             : this(httpClient, null)
         { }
@@ -42,12 +44,19 @@ namespace Microsoft.AspNetCore.Sockets.Client
             _logger = (loggerFactory ?? NullLoggerFactory.Instance).CreateLogger<ServerSentEventsTransport>();
         }
 
-        public Task StartAsync(Uri url, Channel<byte[], SendMessage> application, string connectionId)
+        public Task StartAsync(Uri url, Channel<byte[], SendMessage> application, TransferMode requestedTransferMode, string connectionId)
         {
-            _connectionId = connectionId;
+            if (requestedTransferMode != TransferMode.Binary && requestedTransferMode != TransferMode.Text)
-            _logger.StartTransport(_connectionId);
+            {
+                throw new ArgumentException("Invalid transfer mode.", nameof(requestedTransferMode));
+            }
 
             _application = application;
+            Mode = TransferMode.Text; // Server Sent Events is a text only transport
+            _connectionId = connectionId;
+
+            _logger.StartTransport(_connectionId, Mode.Value);
+
             var sendTask = SendUtils.SendMessages(url, _application, _httpClient, _transportCts, _logger, _connectionId);
             var receiveTask = OpenConnection(_application, url, _transportCts.Token);
 

src/Microsoft.AspNetCore.Sockets.Client.Http/TransferModeFeature.cs

@@ -0,0 +1,12 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using Microsoft.AspNetCore.Sockets.Features;
+
+namespace Microsoft.AspNetCore.Sockets.Client
+{
+    public class TransferModeFeature : ITransferModeFeature
+    {
+        public TransferMode TransferMode { get; set; }
+    }
+}

src/Microsoft.AspNetCore.Sockets.Client.Http/WebSocketsTransport.cs

@@ -22,6 +22,10 @@ namespace Microsoft.AspNetCore.Sockets.Client
         private readonly ILogger _logger;
         private string _connectionId;
 
+        public Task Running { get; private set; } = Task.CompletedTask;
+
+        public TransferMode? Mode { get; private set; }
+
         public WebSocketsTransport()
             : this(null)
         {
@@ -32,9 +36,7 @@ namespace Microsoft.AspNetCore.Sockets.Client
             _logger = (loggerFactory ?? NullLoggerFactory.Instance).CreateLogger<WebSocketsTransport>();
         }
 
-        public Task Running { get; private set; } = Task.CompletedTask;
+        public async Task StartAsync(Uri url, Channel<byte[], SendMessage> application, TransferMode requestedTransferMode, string connectionId)
-
-        public async Task StartAsync(Uri url, Channel<byte[], SendMessage> application, string connectionId)
         {
             if (url == null)
             {
@@ -46,10 +48,17 @@ namespace Microsoft.AspNetCore.Sockets.Client
                 throw new ArgumentNullException(nameof(application));
             }
 
+            if (requestedTransferMode != TransferMode.Binary && requestedTransferMode != TransferMode.Text)
+            {
+                throw new ArgumentException("Invalid transfer mode.", nameof(requestedTransferMode));
+            }
+
             _application = application;
+            Mode = requestedTransferMode;
             _connectionId = connectionId;
 
-            _logger.StartTransport(_connectionId);
+            _logger.StartTransport(_connectionId, Mode.Value);
+
             await Connect(url);
             var sendTask = SendMessages(url);
             var receiveTask = ReceiveMessages(url);
@@ -145,6 +154,11 @@ namespace Microsoft.AspNetCore.Sockets.Client
         {
             _logger.SendStarted(_connectionId);
 
+            var webSocketMessageType =
+                Mode == TransferMode.Binary
+                    ? WebSocketMessageType.Binary
+                    : WebSocketMessageType.Text;
+
             try
             {
                 while (await _application.In.WaitToReadAsync(_transportCts.Token))
@@ -155,7 +169,7 @@ namespace Microsoft.AspNetCore.Sockets.Client
                         {
                             _logger.ReceivedFromApp(_connectionId, message.Payload.Length);
 
-                            await _webSocket.SendAsync(new ArraySegment<byte>(message.Payload), WebSocketMessageType.Text, true, _transportCts.Token);
+                            await _webSocket.SendAsync(new ArraySegment<byte>(message.Payload), webSocketMessageType, true, _transportCts.Token);
 
                             message.SendResult.SetResult(null);
                         }

test/Microsoft.AspNetCore.SignalR.Client.Tests/HttpConnectionTests.cs

@@ -10,16 +10,15 @@ using System.Threading.Tasks;
 using System.Threading.Tasks.Channels;
 using Microsoft.AspNetCore.Client.Tests;
 using Microsoft.AspNetCore.SignalR.Tests.Common;
+using Microsoft.AspNetCore.Sockets.Features;
 using Microsoft.Extensions.Logging;
-using Microsoft.Extensions.Logging.Testing;
 using Moq;
 using Moq.Protected;
 using Xunit;
-using Xunit.Abstractions;
 
 namespace Microsoft.AspNetCore.Sockets.Client.Tests
 {
-    public class ConnectionTests
+    public class HttpConnectionTests
     {
         [Fact]
         public void CannotCreateConnectionWithNullUrl()
@@ -138,7 +137,6 @@ namespace Microsoft.AspNetCore.Sockets.Client.Tests
                         : ResponseUtils.CreateResponse(HttpStatusCode.OK);
                 });
 
-
             var transport = new Mock<ITransport>();
             transport.Setup(t => t.StopAsync()).Returns(async () => { await releaseDisposeTcs.Task; });
             var connection = new HttpConnection(new Uri("http://fakeuri.org/"), new TestTransportFactory(transport.Object), loggerFactory: null, httpMessageHandler: mockHttpHandler.Object);
@@ -154,7 +152,7 @@ namespace Microsoft.AspNetCore.Sockets.Client.Tests
             releaseDisposeTcs.SetResult(null);
             await disposeTask.OrTimeout();
 
-            transport.Verify(t => t.StartAsync(It.IsAny<Uri>(), It.IsAny<Channel<byte[], SendMessage>>(), It.IsAny<string>()), Times.Never);
+            transport.Verify(t => t.StartAsync(It.IsAny<Uri>(), It.IsAny<Channel<byte[], SendMessage>>(), It.IsAny<TransferMode>(), It.IsAny<string>()), Times.Never);
         }
 
         [Fact]
@@ -180,7 +178,6 @@ namespace Microsoft.AspNetCore.Sockets.Client.Tests
                         : ResponseUtils.CreateResponse(HttpStatusCode.OK);
                 });
 
-
             var connection = new HttpConnection(new Uri("http://fakeuri.org/"), TransportType.LongPolling, loggerFactory: null, httpMessageHandler: mockHttpHandler.Object);
 
             await connection.StartAsync();
@@ -205,8 +202,8 @@ namespace Microsoft.AspNetCore.Sockets.Client.Tests
                         : ResponseUtils.CreateResponse(HttpStatusCode.OK);
                 });
 
-
             var connection = new HttpConnection(new Uri("http://fakeuri.org/"), TransportType.LongPolling, loggerFactory: null, httpMessageHandler: mockHttpHandler.Object);
+
             try
             {
                 var connectedEventRaisedTcs = new TaskCompletionSource<object>();
@@ -241,10 +238,9 @@ namespace Microsoft.AspNetCore.Sockets.Client.Tests
                 });
 
             var mockTransport = new Mock<ITransport>();
-            mockTransport.Setup(t => t.StartAsync(It.IsAny<Uri>(), It.IsAny<Channel<byte[], SendMessage>>(), It.IsAny<string>()))
+            mockTransport.Setup(t => t.StartAsync(It.IsAny<Uri>(), It.IsAny<Channel<byte[], SendMessage>>(), It.IsAny<TransferMode>(), It.IsAny<string>()))
                 .Returns(Task.FromException(new InvalidOperationException("Transport failed to start")));
 
-
             var connection = new HttpConnection(new Uri("http://fakeuri.org/"), new TestTransportFactory(mockTransport.Object), loggerFactory: null, httpMessageHandler: mockHttpHandler.Object);
             var connectedEventRaised = false;
 
@@ -281,7 +277,6 @@ namespace Microsoft.AspNetCore.Sockets.Client.Tests
                         : ResponseUtils.CreateResponse(HttpStatusCode.OK);
                 });
 
-
             var connection = new HttpConnection(new Uri("http://fakeuri.org/"), TransportType.LongPolling, loggerFactory: null, httpMessageHandler: mockHttpHandler.Object);
 
             var closedEventTcs = new TaskCompletionSource<Exception>();
@@ -350,8 +345,8 @@ namespace Microsoft.AspNetCore.Sockets.Client.Tests
 
             var mockTransport = new Mock<ITransport>();
             Channel<byte[], SendMessage> channel = null;
-            mockTransport.Setup(t => t.StartAsync(It.IsAny<Uri>(), It.IsAny<Channel<byte[], SendMessage>>(), It.IsAny<string>()))
+            mockTransport.Setup(t => t.StartAsync(It.IsAny<Uri>(), It.IsAny<Channel<byte[], SendMessage>>(), It.IsAny<TransferMode>(), It.IsAny<string>()))
-                .Returns<Uri, Channel<byte[], SendMessage>, string>((url, c, id) =>
+                .Returns<Uri, Channel<byte[], SendMessage>, TransferMode, string>((url, c, transferMode, connectionId) =>
                 {
                     channel = c;
                     return Task.CompletedTask;
@@ -365,9 +360,10 @@ namespace Microsoft.AspNetCore.Sockets.Client.Tests
                     channel.Out.TryComplete();
                     return Task.CompletedTask;
                 });
-
+            mockTransport.SetupGet(t => t.Mode).Returns(TransferMode.Text);
 
             var connection = new HttpConnection(new Uri("http://fakeuri.org/"), new TestTransportFactory(mockTransport.Object), loggerFactory: null, httpMessageHandler: mockHttpHandler.Object);
+
             var receivedInvoked = false;
             connection.Received += m =>
             {
@@ -396,8 +392,8 @@ namespace Microsoft.AspNetCore.Sockets.Client.Tests
 
             var mockTransport = new Mock<ITransport>();
             Channel<byte[], SendMessage> channel = null;
-            mockTransport.Setup(t => t.StartAsync(It.IsAny<Uri>(), It.IsAny<Channel<byte[], SendMessage>>(), It.IsAny<string>()))
+            mockTransport.Setup(t => t.StartAsync(It.IsAny<Uri>(), It.IsAny<Channel<byte[], SendMessage>>(), It.IsAny<TransferMode>(), It.IsAny<string>()))
-                .Returns<Uri, Channel<byte[], SendMessage>, string>((url, c, id) =>
+                .Returns<Uri, Channel<byte[], SendMessage>, TransferMode, string>((url, c, transferMode, connectionId) =>
                 {
                     channel = c;
                     return Task.CompletedTask;
@@ -408,12 +404,13 @@ namespace Microsoft.AspNetCore.Sockets.Client.Tests
                     channel.Out.TryComplete();
                     return Task.CompletedTask;
                 });
-
+            mockTransport.SetupGet(t => t.Mode).Returns(TransferMode.Text);
 
             var callbackInvokedTcs = new TaskCompletionSource<object>();
             var closedTcs = new TaskCompletionSource<object>();
 
             var connection = new HttpConnection(new Uri("http://fakeuri.org/"), new TestTransportFactory(mockTransport.Object), loggerFactory: null, httpMessageHandler: mockHttpHandler.Object);
+
             connection.Received +=
                 async m =>
                 {
@@ -584,7 +581,6 @@ namespace Microsoft.AspNetCore.Sockets.Client.Tests
                 });
 
             var connection = new HttpConnection(new Uri("http://fakeuri.org/"), TransportType.LongPolling, loggerFactory: null, httpMessageHandler: mockHttpHandler.Object);
-
             await connection.StartAsync();
 
             var exception = await Assert.ThrowsAsync<HttpRequestException>(
@@ -773,5 +769,48 @@ namespace Microsoft.AspNetCore.Sockets.Client.Tests
 
             Assert.Equal("No requested transports available on the server.", exception.Message);
         }
+
+        [Fact]
+        public async Task CanStartConnectionWithoutSettingTransferModeFeature()
+        {
+            var mockHttpHandler = new Mock<HttpMessageHandler>();
+            mockHttpHandler.Protected()
+                .Setup<Task<HttpResponseMessage>>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>())
+                .Returns<HttpRequestMessage, CancellationToken>(async (request, cancellationToken) =>
+                {
+                    await Task.Yield();
+                    return request.Method == HttpMethod.Options
+                        ? ResponseUtils.CreateResponse(HttpStatusCode.OK, ResponseUtils.CreateNegotiationResponse())
+                        : ResponseUtils.CreateResponse(HttpStatusCode.OK);
+                });
+
+            var mockTransport = new Mock<ITransport>();
+            Channel<byte[], SendMessage> channel = null;
+            mockTransport.Setup(t => t.StartAsync(It.IsAny<Uri>(), It.IsAny<Channel<byte[], SendMessage>>(), It.IsAny<TransferMode>(), It.IsAny<string>()))
+                .Returns<Uri, Channel<byte[], SendMessage>, TransferMode, string>((url, c, transferMode, connectionId) =>
+                {
+                    channel = c;
+                    return Task.CompletedTask;
+                });
+            mockTransport.Setup(t => t.StopAsync())
+                .Returns(() =>
+                {
+                    channel.Out.TryComplete();
+                    return Task.CompletedTask;
+                });
+            mockTransport.SetupGet(t => t.Mode).Returns(TransferMode.Binary);
+
+            var connection = new HttpConnection(new Uri("http://fakeuri.org/"), new TestTransportFactory(mockTransport.Object),
+                loggerFactory: null, httpMessageHandler: mockHttpHandler.Object);
+
+            await connection.StartAsync().OrTimeout();
+            var transferModeFeature = connection.Features.Get<ITransferModeFeature>();
+            await connection.DisposeAsync().OrTimeout();
+
+            mockTransport.Verify(t => t.StartAsync(
+                It.IsAny<Uri>(), It.IsAny<Channel<byte[], SendMessage>>(), TransferMode.Text, It.IsAny<string>()), Times.Once);
+            Assert.NotNull(transferModeFeature);
+            Assert.Equal(TransferMode.Binary, transferModeFeature.TransferMode);
+        }
     }
 }

test/Microsoft.AspNetCore.SignalR.Client.Tests/HubConnectionTests.cs

@@ -5,6 +5,7 @@ using System;
 using System.Collections.Generic;
 using System.IO;
 using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.SignalR.Internal;
 using Microsoft.AspNetCore.SignalR.Internal.Protocol;
 using Microsoft.AspNetCore.SignalR.Tests.Common;
@@ -21,6 +22,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
         public async Task StartAsyncCallsConnectionStart()
         {
             var connection = new Mock<IConnection>();
+            connection.SetupGet(p => p.Features).Returns(new FeatureCollection());
             connection.Setup(m => m.StartAsync()).Returns(Task.CompletedTask).Verifiable();
             var hubConnection = new HubConnection(connection.Object);
             await hubConnection.StartAsync();
@@ -125,6 +127,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
         {
             var exception = new InvalidOperationException();
             var mockConnection = new Mock<IConnection>();
+            mockConnection.SetupGet(p => p.Features).Returns(new FeatureCollection());
             mockConnection
                 .Setup(m => m.DisposeAsync())
                 .Callback(() => mockConnection.Raise(c => c.Closed += null, exception))
@@ -144,6 +147,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
         public async Task DoesNotThrowWhenClientMethodCalledButNoInvocationHandlerHasBeenSetUp()
         {
             var mockConnection = new Mock<IConnection>();
+            mockConnection.SetupGet(p => p.Features).Returns(new FeatureCollection());
 
             var invocation = new InvocationMessage(Guid.NewGuid().ToString(), nonBlocking: true, target: "NonExistingMethod123", arguments: new object[] { true, "arg2", 123 });
 
@@ -181,7 +185,9 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
                 };
             }
 
-            public string Name { get => "MockHubProtocol"; }
+            public string Name => "MockHubProtocol";
+
+            public ProtocolType Type => ProtocolType.Binary;
 
             public bool TryParseMessages(ReadOnlyBuffer<byte> input, IInvocationBinder binder, out IList<HubMessage> messages)
             {

test/Microsoft.AspNetCore.SignalR.Client.Tests/LongPollingTransportTests.cs

@@ -10,6 +10,7 @@ using System.Threading;
 using System.Threading.Tasks;
 using System.Threading.Tasks.Channels;
 using Microsoft.AspNetCore.SignalR.Tests.Common;
+using Microsoft.AspNetCore.Sockets;
 using Microsoft.AspNetCore.Sockets.Client;
 using Microsoft.AspNetCore.Sockets.Internal;
 using Moq;
@@ -43,7 +44,7 @@ namespace Microsoft.AspNetCore.Client.Tests
                     var connectionToTransport = Channel.CreateUnbounded<SendMessage>();
                     var transportToConnection = Channel.CreateUnbounded<byte[]>();
                     var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
-                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty);
+                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, TransferMode.Binary, connectionId: string.Empty);
 
                     transportActiveTask = longPollingTransport.Running;
 
@@ -79,7 +80,7 @@ namespace Microsoft.AspNetCore.Client.Tests
                     var connectionToTransport = Channel.CreateUnbounded<SendMessage>();
                     var transportToConnection = Channel.CreateUnbounded<byte[]>();
                     var channelConnection = ChannelConnection.Create(connectionToTransport, transportToConnection);
-                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty);
+                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, TransferMode.Binary, connectionId: string.Empty);
 
                     await longPollingTransport.Running.OrTimeout();
                     Assert.True(transportToConnection.In.Completion.IsCompleted);
@@ -132,7 +133,7 @@ namespace Microsoft.AspNetCore.Client.Tests
                     var connectionToTransport = Channel.CreateUnbounded<SendMessage>();
                     var transportToConnection = Channel.CreateUnbounded<byte[]>();
                     var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
-                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty);
+                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, TransferMode.Binary, connectionId: string.Empty);
 
                     var data = await transportToConnection.In.ReadAllAsync().OrTimeout();
                     await longPollingTransport.Running.OrTimeout();
@@ -168,7 +169,7 @@ namespace Microsoft.AspNetCore.Client.Tests
                     var connectionToTransport = Channel.CreateUnbounded<SendMessage>();
                     var transportToConnection = Channel.CreateUnbounded<byte[]>();
                     var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
-                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty);
+                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, TransferMode.Binary, connectionId: string.Empty);
 
                     var exception =
                         await Assert.ThrowsAsync<HttpRequestException>(async () => await transportToConnection.In.Completion.OrTimeout());
@@ -204,7 +205,7 @@ namespace Microsoft.AspNetCore.Client.Tests
                     var connectionToTransport = Channel.CreateUnbounded<SendMessage>();
                     var transportToConnection = Channel.CreateUnbounded<byte[]>();
                     var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
-                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty);
+                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, TransferMode.Binary, connectionId: string.Empty);
 
                     await connectionToTransport.Out.WriteAsync(new SendMessage());
 
@@ -245,7 +246,7 @@ namespace Microsoft.AspNetCore.Client.Tests
                     var connectionToTransport = Channel.CreateUnbounded<SendMessage>();
                     var transportToConnection = Channel.CreateUnbounded<byte[]>();
                     var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
-                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty);
+                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, TransferMode.Binary, connectionId: string.Empty);
 
                     connectionToTransport.Out.Complete();
 
@@ -296,7 +297,7 @@ namespace Microsoft.AspNetCore.Client.Tests
                     var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
 
                     // Start the transport
-                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty);
+                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, TransferMode.Binary, connectionId: string.Empty);
 
                     // Wait for the transport to finish
                     await longPollingTransport.Running.OrTimeout();
@@ -361,7 +362,7 @@ namespace Microsoft.AspNetCore.Client.Tests
                     await connectionToTransport.Out.WriteAsync(new SendMessage(Encoding.UTF8.GetBytes("World"), tcs2)).OrTimeout();
 
                     // Start the transport
-                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty);
+                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, TransferMode.Binary, connectionId: string.Empty);
 
                     connectionToTransport.Out.Complete();
 
@@ -378,5 +379,63 @@ namespace Microsoft.AspNetCore.Client.Tests
                 }
             }
         }
+
+        [Theory]
+        [InlineData(TransferMode.Binary)]
+        [InlineData(TransferMode.Text)]
+        public async Task LongPollingTransportSetsTransferMode(TransferMode transferMode)
+        {
+            var mockHttpHandler = new Mock<HttpMessageHandler>();
+            mockHttpHandler.Protected()
+                .Setup<Task<HttpResponseMessage>>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>())
+                .Returns<HttpRequestMessage, CancellationToken>(async (request, cancellationToken) =>
+                {
+                    await Task.Yield();
+                    return ResponseUtils.CreateResponse(HttpStatusCode.OK);
+                });
+
+            using (var httpClient = new HttpClient(mockHttpHandler.Object))
+            {
+                var longPollingTransport = new LongPollingTransport(httpClient);
+
+                try
+                {
+                    var connectionToTransport = Channel.CreateUnbounded<SendMessage>();
+                    var transportToConnection = Channel.CreateUnbounded<byte[]>();
+                    var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
+
+                    Assert.Null(longPollingTransport.Mode);
+                    await longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, transferMode, connectionId: string.Empty);
+                    Assert.Equal(transferMode, longPollingTransport.Mode);
+                }
+                finally
+                {
+                    await longPollingTransport.StopAsync();
+                }
+            }
+        }
+
+        [Fact]
+        public async Task LongPollingTransportThrowsForInvalidTransferMode()
+        {
+            var mockHttpHandler = new Mock<HttpMessageHandler>();
+            mockHttpHandler.Protected()
+                .Setup<Task<HttpResponseMessage>>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>())
+                .Returns<HttpRequestMessage, CancellationToken>(async (request, cancellationToken) =>
+                {
+                    await Task.Yield();
+                    return ResponseUtils.CreateResponse(HttpStatusCode.OK);
+                });
+
+            using (var httpClient = new HttpClient(mockHttpHandler.Object))
+            {
+                var longPollingTransport = new LongPollingTransport(httpClient);
+                var exception = await Assert.ThrowsAsync<ArgumentException>(() =>
+                    longPollingTransport.StartAsync(new Uri("http://fakeuri.org"), null, TransferMode.Text | TransferMode.Binary, connectionId: string.Empty));
+
+                Assert.Contains("Invalid transfer mode.", exception.Message);
+                Assert.Equal("requestedTransferMode", exception.ParamName);
+            }
+        }
     }
 }

test/Microsoft.AspNetCore.SignalR.Client.Tests/ServerSentEventsTransportTests.cs

@@ -11,6 +11,7 @@ using System.Threading.Tasks;
 using System.Threading.Tasks.Channels;
 using Microsoft.AspNetCore.Client.Tests;
 using Microsoft.AspNetCore.SignalR.Tests.Common;
+using Microsoft.AspNetCore.Sockets;
 using Microsoft.AspNetCore.Sockets.Client;
 using Microsoft.AspNetCore.Sockets.Internal;
 using Moq;
@@ -52,7 +53,8 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
                     var connectionToTransport = Channel.CreateUnbounded<SendMessage>();
                     var transportToConnection = Channel.CreateUnbounded<byte[]>();
                     var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
-                    await sseTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty).OrTimeout();
+                    await sseTransport.StartAsync(
+                        new Uri("http://fakeuri.org"), channelConnection, TransferMode.Text, connectionId: string.Empty).OrTimeout();
 
                     await eventStreamTcs.Task.OrTimeout();
                     await sseTransport.StopAsync().OrTimeout();
@@ -103,7 +105,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
                     var transportToConnection = Channel.CreateUnbounded<byte[]>();
                     var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
                     await sseTransport.StartAsync(
-                        new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty).OrTimeout();
+                        new Uri("http://fakeuri.org"), channelConnection, TransferMode.Text, connectionId: string.Empty).OrTimeout();
 
                     transportActiveTask = sseTransport.Running;
                     Assert.False(transportActiveTask.IsCompleted);
@@ -150,7 +152,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
                 var transportToConnection = Channel.CreateUnbounded<byte[]>();
                 var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
                 await sseTransport.StartAsync(
-                    new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty).OrTimeout();
+                    new Uri("http://fakeuri.org"), channelConnection, TransferMode.Text, connectionId: string.Empty).OrTimeout();
 
                 var exception = await Assert.ThrowsAsync<FormatException>(() => sseTransport.Running.OrTimeout());
                 Assert.Equal("Incomplete message.", exception.Message);
@@ -195,7 +197,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
                 var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
 
                 await sseTransport.StartAsync(
-                    new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty).OrTimeout();
+                    new Uri("http://fakeuri.org"), channelConnection, TransferMode.Text, connectionId: string.Empty).OrTimeout();
                 await eventStreamTcs.Task;
 
                 var sendTcs = new TaskCompletionSource<object>();
@@ -241,7 +243,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
                 var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
 
                 await sseTransport.StartAsync(
-                    new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty).OrTimeout();
+                    new Uri("http://fakeuri.org"), channelConnection, TransferMode.Text, connectionId: string.Empty).OrTimeout();
                 await eventStreamTcs.Task.OrTimeout();
 
                 connectionToTransport.Out.TryComplete(null);
@@ -270,7 +272,7 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
                 var transportToConnection = Channel.CreateUnbounded<byte[]>();
                 var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
                 await sseTransport.StartAsync(
-                    new Uri("http://fakeuri.org"), channelConnection, connectionId: string.Empty).OrTimeout();
+                    new Uri("http://fakeuri.org"), channelConnection, TransferMode.Text, connectionId: string.Empty).OrTimeout();
 
                 var message = await transportToConnection.In.ReadAsync().AsTask().OrTimeout();
                 Assert.Equal("3:abc", Encoding.ASCII.GetString(message));
@@ -278,5 +280,58 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
                 await sseTransport.Running.OrTimeout();
             }
         }
+
+        [Theory]
+        [InlineData(TransferMode.Text)]
+        [InlineData(TransferMode.Binary)]
+        public async Task SSETransportSetsTransferMode(TransferMode transferMode)
+        {
+            var mockHttpHandler = new Mock<HttpMessageHandler>();
+            mockHttpHandler.Protected()
+                .Setup<Task<HttpResponseMessage>>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>())
+                .Returns<HttpRequestMessage, CancellationToken>(async (request, cancellationToken) =>
+                {
+                    await Task.Yield();
+                    return new HttpResponseMessage { Content = new StringContent(string.Empty) };
+                });
+
+            using (var httpClient = new HttpClient(mockHttpHandler.Object))
+            {
+                var sseTransport = new ServerSentEventsTransport(httpClient);
+                var connectionToTransport = Channel.CreateUnbounded<SendMessage>();
+                var transportToConnection = Channel.CreateUnbounded<byte[]>();
+                var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
+                Assert.Null(sseTransport.Mode);
+                await sseTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, transferMode, connectionId: string.Empty).OrTimeout();
+                Assert.Equal(TransferMode.Text, sseTransport.Mode);
+                await sseTransport.StopAsync().OrTimeout();
+            }
+        }
+
+        [Fact]
+        public async Task SSETransportThrowsForInvalidTransferMode()
+        {
+            var mockHttpHandler = new Mock<HttpMessageHandler>();
+            mockHttpHandler.Protected()
+                .Setup<Task<HttpResponseMessage>>("SendAsync", ItExpr.IsAny<HttpRequestMessage>(), ItExpr.IsAny<CancellationToken>())
+                .Returns<HttpRequestMessage, CancellationToken>(async (request, cancellationToken) =>
+                {
+                    await Task.Yield();
+                    return new HttpResponseMessage { Content = new StringContent(string.Empty) };
+                });
+
+            using (var httpClient = new HttpClient(mockHttpHandler.Object))
+            {
+                var sseTransport = new ServerSentEventsTransport(httpClient);
+                var connectionToTransport = Channel.CreateUnbounded<SendMessage>();
+                var transportToConnection = Channel.CreateUnbounded<byte[]>();
+                var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
+                var exception = await Assert.ThrowsAsync<ArgumentException>(() =>
+                    sseTransport.StartAsync(new Uri("http://fakeuri.org"), null, TransferMode.Text | TransferMode.Binary, connectionId: string.Empty));
+
+                Assert.Contains("Invalid transfer mode.", exception.Message);
+                Assert.Equal("requestedTransferMode", exception.ParamName);
+            }
+        }
     }
 }

test/Microsoft.AspNetCore.SignalR.Client.Tests/TestConnection.cs

@@ -7,6 +7,7 @@ using System.Text;
 using System.Threading;
 using System.Threading.Tasks;
 using System.Threading.Tasks.Channels;
+using Microsoft.AspNetCore.Http.Features;
 using Microsoft.AspNetCore.Sockets.Client;
 using Microsoft.AspNetCore.Sockets.Internal.Formatters;
 using Newtonsoft.Json;
@@ -34,6 +35,8 @@ namespace Microsoft.AspNetCore.SignalR.Client.Tests
         public ReadableChannel<byte[]> SentMessages => _sentMessages.In;
         public WritableChannel<byte[]> ReceivedMessages => _receivedMessages.Out;
 
+        public IFeatureCollection Features { get; } = new FeatureCollection();
+
         public TestConnection()
         {
             _receiveLoop = ReceiveLoopAsync(_receiveShutdownToken.Token);

test/Microsoft.AspNetCore.SignalR.Tests/EndToEndTests.cs

@@ -11,6 +11,7 @@ using System.Threading.Tasks;
 using Microsoft.AspNetCore.SignalR.Client;
 using Microsoft.AspNetCore.SignalR.Tests.Common;
 using Microsoft.AspNetCore.Sockets;
+using Microsoft.AspNetCore.Sockets.Features;
 using Microsoft.AspNetCore.Sockets.Client;
 using Microsoft.AspNetCore.Testing.xunit;
 using Microsoft.Extensions.Logging;
@@ -78,6 +79,7 @@ namespace Microsoft.AspNetCore.SignalR.Tests
         [ConditionalTheory]
         [OSSkipCondition(OperatingSystems.Windows, WindowsVersions.Win7, WindowsVersions.Win2008R2, SkipReason = "No WebSockets Client for this platform")]
         [MemberData(nameof(TransportTypes))]
+        // TODO: transfer types
         public async Task ConnectionCanSendAndReceiveMessages(TransportType transportType)
         {
             using (StartLog(out var loggerFactory, testName: $"ConnectionCanSendAndReceiveMessages_{transportType.ToString()}"))
@@ -88,6 +90,9 @@ namespace Microsoft.AspNetCore.SignalR.Tests
 
                 var url = _serverFixture.BaseUrl + "/echo";
                 var connection = new HttpConnection(new Uri(url), transportType, loggerFactory);
+
+                connection.Features.Set<ITransferModeFeature>(
+                    new TransferModeFeature { TransferMode = TransferMode.Text });
                 try
                 {
                     var receiveTcs = new TaskCompletionSource<string>();
@@ -163,6 +168,9 @@ namespace Microsoft.AspNetCore.SignalR.Tests
 
                 var url = _serverFixture.BaseUrl + "/echo";
                 var connection = new HttpConnection(new Uri(url), loggerFactory);
+                connection.Features.Set<ITransferModeFeature>(
+                    new TransferModeFeature { TransferMode = TransferMode.Binary });
+
                 try
                 {
                     var receiveTcs = new TaskCompletionSource<byte[]>();

test/Microsoft.AspNetCore.SignalR.Tests/WebSocketsTransportTests.cs

@@ -5,6 +5,7 @@ using System;
 using System.Threading.Tasks;
 using System.Threading.Tasks.Channels;
 using Microsoft.AspNetCore.SignalR.Tests.Common;
+using Microsoft.AspNetCore.Sockets;
 using Microsoft.AspNetCore.Sockets.Client;
 using Microsoft.AspNetCore.Sockets.Internal;
 using Microsoft.AspNetCore.Testing.xunit;
@@ -40,7 +41,8 @@ namespace Microsoft.AspNetCore.SignalR.Tests
                 var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
 
                 var webSocketsTransport = new WebSocketsTransport(loggerFactory);
-                await webSocketsTransport.StartAsync(new Uri(_serverFixture.WebSocketsUrl + "/echo"), channelConnection, connectionId: string.Empty).OrTimeout();
+                await webSocketsTransport.StartAsync(new Uri(_serverFixture.WebSocketsUrl + "/echo"), channelConnection,
+                    TransferMode.Binary, connectionId: string.Empty).OrTimeout();
                 await webSocketsTransport.StopAsync().OrTimeout();
                 await webSocketsTransport.Running.OrTimeout();
             }
@@ -57,15 +59,18 @@ namespace Microsoft.AspNetCore.SignalR.Tests
                 var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
 
                 var webSocketsTransport = new WebSocketsTransport(loggerFactory);
-                await webSocketsTransport.StartAsync(new Uri(_serverFixture.WebSocketsUrl + "/echo"), channelConnection, connectionId: string.Empty);
+                await webSocketsTransport.StartAsync(new Uri(_serverFixture.WebSocketsUrl + "/echo"), channelConnection,
+                    TransferMode.Binary, connectionId: string.Empty);
                 connectionToTransport.Out.TryComplete();
                 await webSocketsTransport.Running.OrTimeout();
             }
         }
 
-        [ConditionalFact]
+        [ConditionalTheory]
         [OSSkipCondition(OperatingSystems.Windows, WindowsVersions.Win7, WindowsVersions.Win2008R2, SkipReason = "No WebSockets Client for this platform")]
-        public async Task WebSocketsTransportStopsWhenConnectionClosedByTheServer()
+        [InlineData(TransferMode.Text)]
+        [InlineData(TransferMode.Binary)]
+        public async Task WebSocketsTransportStopsWhenConnectionClosedByTheServer(TransferMode transferMode)
         {
             using (StartLog(out var loggerFactory))
             {
@@ -74,7 +79,7 @@ namespace Microsoft.AspNetCore.SignalR.Tests
                 var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
 
                 var webSocketsTransport = new WebSocketsTransport(loggerFactory);
-                await webSocketsTransport.StartAsync(new Uri(_serverFixture.WebSocketsUrl + "/echo"), channelConnection, connectionId: string.Empty);
+                await webSocketsTransport.StartAsync(new Uri(_serverFixture.WebSocketsUrl + "/echo"), channelConnection, transferMode, connectionId: string.Empty);
 
                 var sendTcs = new TaskCompletionSource<object>();
                 connectionToTransport.Out.TryWrite(new SendMessage(new byte[] { 0x42 }, sendTcs));
@@ -86,5 +91,48 @@ namespace Microsoft.AspNetCore.SignalR.Tests
                 Assert.Equal(new byte[] { 0x42 }, buffer);
             }
         }
+
+        [ConditionalTheory]
+        [OSSkipCondition(OperatingSystems.Windows, WindowsVersions.Win7, WindowsVersions.Win2008R2, SkipReason = "No WebSockets Client for this platform")]
+        [InlineData(TransferMode.Text)]
+        [InlineData(TransferMode.Binary)]
+        public async Task WebSocketsTransportSetsTransferMode(TransferMode transferMode)
+        {
+            using (StartLog(out var loggerFactory))
+            {
+                var connectionToTransport = Channel.CreateUnbounded<SendMessage>();
+                var transportToConnection = Channel.CreateUnbounded<byte[]>();
+                var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
+
+                var webSocketsTransport = new WebSocketsTransport(loggerFactory);
+
+                Assert.Null(webSocketsTransport.Mode);
+                await webSocketsTransport.StartAsync(new Uri(_serverFixture.WebSocketsUrl + "/echo"), channelConnection,
+                    transferMode, connectionId: string.Empty).OrTimeout();
+                Assert.Equal(transferMode, webSocketsTransport.Mode);
+
+                await webSocketsTransport.StopAsync().OrTimeout();
+                await webSocketsTransport.Running.OrTimeout();
+            }
+        }
+
+        [ConditionalFact]
+        [OSSkipCondition(OperatingSystems.Windows, WindowsVersions.Win7, WindowsVersions.Win2008R2, SkipReason = "No WebSockets Client for this platform")]
+        public async Task WebSocketsTransportThrowsForInvalidTransferMode()
+        {
+            using (StartLog(out var loggerFactory))
+            {
+                var connectionToTransport = Channel.CreateUnbounded<SendMessage>();
+                var transportToConnection = Channel.CreateUnbounded<byte[]>();
+                var channelConnection = new ChannelConnection<SendMessage, byte[]>(connectionToTransport, transportToConnection);
+
+                var webSocketsTransport = new WebSocketsTransport(loggerFactory);
+                var exception = await Assert.ThrowsAsync<ArgumentException>(() =>
+                    webSocketsTransport.StartAsync(new Uri("http://fakeuri.org"), channelConnection, TransferMode.Text | TransferMode.Binary, connectionId: string.Empty));
+
+                Assert.Contains("Invalid transfer mode.", exception.Message);
+                Assert.Equal("requestedTransferMode", exception.ParamName);
+            }
+        }
     }
 }