SignalR 服务器在客户端连接时立即关闭连接

Question

我想在项目中使用 SignalR 向设备发送重启消息，但我不能。因此，我决定启动一个新的解决方案，仅用于测试目的，并获得相同的结果：

SocketException (0x80004005): 现有连接被远程主机强制关闭

我正在使用 Visual Studio Professional 2017 和 .NET 4.7.2，以下是我遵循的步骤：

1. 我使用名为 的 ASP.NET Web App 项目创建了一个新的解决方案SignalRServer，并使用 Indentity 进行身份验证。
2. 我创建名为的新文件夹SignalR并添加新项目 > SignalR Hub Class (v2)。我把它命名为SignalRHub：

public class SignalRHub : Hub
{
    public void Reboot()
    {
        Clients.All.reboot();
    }
    public void Hello()
    {
        Clients.All.hello();
    }
    public override Task OnConnected()
    {
        Debug.WriteLine($"[SERVER] {this.Context.ConnectionId} connected");
        return base.OnConnected();
    }
    public override Task OnReconnected()
    {
        Debug.WriteLine($"[SERVER] {this.Context.ConnectionId} reconnected");
        return base.OnReconnected();
    }
    public override Task OnDisconnected(bool stopCalled)
    {
        Debug.WriteLine($"[SERVER] {this.Context.ConnectionId} disconnected");
        return base.OnDisconnected(stopCalled);
    }
}

3. 在 Startup.cs 文件中：

    public partial class Startup
    {
        public void Configuration(IAppBuilder app)
        {
            app.MapSignalR();
            ConfigureAuth(app);
        }
    }

服务器实现完成。之后，客户：

4. 我添加了一个名为 的新 WPF 项目SignalRClient。
5. 我使用 Nuget 添加Microsoft.AspNet.SignalR.Client包。
6. 我改变MainWindow.xaml：

<Window x:Class="SignalRClient.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:SignalRClient"
        mc:Ignorable="d"
        Title="MainWindow" Height="300" Width="400" Loaded="Window_Loaded">
    <Grid>
        <Button VerticalAlignment="Center" HorizontalAlignment="Center" Padding="5" Content="Send message!" Click="Button_Click"/>
    </Grid>
</Window>

7. 最后我改变了MainWindow.xaml.cs：

public partial class MainWindow : Window
{
    private IHubProxy signalRHubProxy;

    public MainWindow()
    {
        InitializeComponent();
    }

    private async void Window_Loaded(object sender, RoutedEventArgs e)
    {
        try
        {
            using (var hubConnection = new HubConnection("http://localhost:54475/"))
            {
                this.signalRHubProxy = hubConnection.CreateHubProxy("SignalRHub");
                this.signalRHubProxy.On("Hello", this.HelloMessageReceived);
                this.signalRHubProxy.On("Reboot", this.RebootMessageReceived);
                ServicePointManager.DefaultConnectionLimit = 10;
                await hubConnection.Start();
                Debug.WriteLine($"[CLIENT] Connected to hub");
            }
        }
        catch (Exception exception)
        {
            Debug.WriteLine($"[CLIENT] {exception.Message}");
        }
    }

    private void HelloMessageReceived()
    {
        Console.WriteLine("[CLIENT] Hello message received");
    }
    private void RebootMessageReceived()
    {
        Console.WriteLine("[CLIENT] Reboot message received");
    }

    private async void Button_Click(object sender, RoutedEventArgs e)
    {
        await this.signalRHubProxy.Invoke("Hello", new { });
    }
}

客户端也完成了。现在，我首先运行 Web 应用程序，加载主页后运行 WPF 应用程序（“调试”>“启动新实例”）。这是输出：

[SERVER] b3f11c77-6bfc-416a-914b-f2573f0cc42c connected
[CLIENT] Connected to hub
[SERVER] b3f11c77-6bfc-416a-914b-f2573f0cc42c disconnected
SignalRClient.exe Error: 0 : Error while closing the websocket: System.Net.WebSockets.WebSocketException (0x80004005): An internal WebSocket error occurred. Please see the innerException, if present, for more details.  ---> System.Net.Sockets.SocketException (0x80004005): An existing connection was forcibly closed by the remote host
   at System.Net.WebSockets.WebSocketConnectionStream.WebSocketConnection.WriteAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
   at System.Net.DelegatedStream.WriteAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
   at System.Net.WebSockets.WebSocketConnectionStream.<>n__1(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
   at System.Net.WebSockets.WebSocketConnectionStream.<WriteAsync>d__22.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Net.WebSockets.WebSocketBase.<SendFrameAsync>d__48.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.ValidateEnd(Task task)
   at System.Net.WebSockets.WebSocketBase.WebSocketOperation.<Process>d__19.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at System.Net.WebSockets.WebSocketBase.<CloseOutputAsyncCore>d__51.MoveNext()
   at System.Net.WebSockets.WebSocketBase.ThrowIfConvertibleException(String methodName, Exception exception, CancellationToken cancellationToken, Boolean aborted)
   at System.Net.WebSockets.WebSocketBase.<CloseOutputAsyncCore>d__51.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.CompilerServices.TaskAwaiter.ThrowForNonSuccess(Task task)
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNet.SignalR.WebSockets.WebSocketHandler.<>c.<<CloseAsync>b__13_0>d.MoveNext() in /_/src/Microsoft.AspNet.SignalR.Core/Owin/WebSockets/WebSocketHandler.cs:line 114
The thread 0x4b44 has exited with code 0 (0x0).
The thread 0x5560 has exited with code 0 (0x0).

我可以看到客户端连接到服务器，但连接立即关闭。不知道是不是我忘记了一步。我停止了防火墙，结果相同。你知道我该如何解决这个问题吗？

Answer 1

看来using语句是原因，因为它HubConnection在块末尾处置了创建的对象try，这导致 websocket 关闭。

您可以考虑删除using语句并保存hubConnection为字段或属性，以便hubConnection.Stop()稍后调用以断开连接。