SignalR核心控制台客户端没有收到通知

Question

我看了一些类似的问题，没有弄明白这个问题。 在我的.NET核心Web API项目中，我有一个简单的Hub。 这里是Hub。

 public class NotificationHub : Hub<INotificationClient>
{
  public async Task SendMessage(string user, string msg)
    {
        await Clients.All.ReceiveMessage(user, msg);
    }
    public Task SendMessageToCaller(string msg)
    {
        return Clients.Caller.ReceiveMessage(msg);
    }

    public Task SendMessageToPartner(string user, string msg)
    {
        return Clients.Client(user).ReceiveMessageToPartner(msg);
    }
}

这里是接口

 public interface INotificationClient
{
    Task ReceiveMessage(string user, string msg);
    Task ReceiveMessage(string msg);
    Task ReceiveMessageToPartner( string msg);

}

这里是控制器的代码

[Route("[controller]")]
[ApiController]
public class NotificationsController : ControllerBase
{
    private IHubContext<NotificationHub> _hub;

    public NotificationsController(IHubContext<NotificationHub> hub)
    {
        _hub = hub;

    }
    [HttpGet]
    public async Task<IActionResult> Get()
    {
        var msg = new NotificationData { ClientId = "12345", Notification = "Somone just connected" };
        await _hub.Clients.All.SendAsync("Notification", msg);
        return Ok(new { Message = "Request complete" });
    }
}

最后是控制台客户端代码

 Console.WriteLine("Press a key to start listening");
        Console.ReadKey();

        Console.WriteLine("Client Listening!");
        var connection = new HubConnectionBuilder()
           .WithUrl("http://localhost:61514/notifications")

           .Build();


        connection.On<NotificationData>("Notification", (notificationData) =>
            Console.WriteLine($"Somebody connected: {notificationData.ClientId}"));

        connection.StartAsync().GetAwaiter().GetResult();

        Console.WriteLine("Listening. Press a key to quit");
        Console.ReadKey();

这里是带映射的web应用的启动过程。

 public void ConfigureServices(IServiceCollection services)
    {
        services.AddSignalR();
        services.AddControllers();
    }

    // This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
    public void Configure(IApplicationBuilder app, IWebHostEnvironment env)
    {
        if (env.IsDevelopment())
        {
            app.UseDeveloperExceptionPage();
        }

        app.UseRouting();

        app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
            endpoints.MapHub<NotificationHub>("/Notifications");
        });
    }

我一直收到这个错误： System.IO.IOException: "服务器在握手开始前断开了连接 我一定是在这一过程中遗漏了什么。

更新：打开日志，得到这个错误。

dbug: Microsoft.AspNetCore.HttpException: "服务器在握手开始前断开连接 Microsoft.AspNetCore.Http.Connections.Client.HttpConnection[8] Establishing connection with server at '。http:/localhost:61514通知。'.dbug.AspNetCore.Http.Connections.Client.HttpConnection[9] 与服务器建立连接'BdROAEEQnGUeDYAW5EspRA'。Microsoft.AspNetCore.Http.Connections.Client.HttpConnection[9] 与服务器建立连接'BdROAEEQnGUeDYAW5EspRA'。Microsoft.AspNetCore.Http.Connections.Client.HttpConnection[7] 启动传输'ServerSentEvents'的Url: http:/localhost:61514notifications。...信息。Microsoft.AspNetCore.Http.Connections.Client.Internal.ServerSentEventsTransport[1] 开始传输。传输模式。传输模式：Text.dbug: Microsoft.AspNetCore.Http.Connections.Client.Internal.ServerSentEventsTransport[3] 开始接收循环。Microsoft.AspNetCore.Http.Connections.Client.Internal.ServerSentEventsTransport[9] 收到30个字节，解析SSE帧。解析SSE帧。 dbug.AspNetCore.Http.Connect.Client.Internal.ServerSentEventsTransport[9]接收到30个字节，解析SSE帧。Microsoft.AspNetCore.Http.Connections.Client.Internal.ServerSentEventsTransport[4] 接收循环停止。Microsoft.AspNetCore.Http.Connections.Client.Internal.ServerSentEventsTransport[100] 开始发送循环。Microsoft.AspNetCore.Http.Connections.Client.HttpConnection[18] 传送'ServerSentEvents'开始。Microsoft.AspNetCore.Http.Connections.Client.Internal.ServerSentEventsTransport[102] 发送循环被取消。Microsoft.AspNetCore.Http.Connections.Client.Internal.ServerSentEventsTransport[101] 发送循环停止。 未处理的异常。Info.AspNetCore.Http.Connections.Client.Internal.ServerSentEventsTransport[101] Send loop stopped: Microsoft.AspNetCore.Http.Connections.Client.HttpConnection[3] HttpConnection Started.info: Microsoft.AspNetCore.SignalR.Client.HubConnection[24] Using HubProtocol 'json v1'. System.IO.IOException: 在Microsoft.AspNetCore.SignalR.Client.HubConnection.HandshakeAsync(ConnectionState startingConnectionState, CancellationToken cancellationToken) 在Microsoft.AspNetCore.SignalR.Client.HubConnection.StartAsyncCore(CancellationToken cancellationToken) 在Microsoft.AspNetCore.SignalR.Client.HubConnection. 在Microsoft.AspNetCore.SignalR.Client.HubConnection.StartAsyncCore(CancellationToken cancellationToken) at Microsoft.AspNetCore.SignalR.Client.HubConnection.StartAsyncInner(CancellationToken cancellationToken) at System.Threading.Tasks.ForceAsyncAwaiter.GetResult() at Microsoft.AspNetCore.SignalR.Client.HubConnection.StartAsync(CancellationToken cancellationToken) at NotificationClient.Program.Main(String[] args)

Answer 1

所以，在喋喋不休地讨论了一整天之后，我发现了问题所在，所以我想我应该把解决方案发布在这里，以防有人遇到这个问题。

Hub端点是指向控制器的。 所以当客户机连接时，它击中控制器两次，导致服务器关闭连接。 所以我修改了这一行。

app.UseEndpoints(endpoints =>
        {
            endpoints.MapControllers();
            endpoints.MapHub<NotificationHub>("/Notify");
        });

从 "Notifications "改成 "Notify"，就像上面的代码一样 把客户端从 "Notifications "改成 "Notify

 var connection = new HubConnectionBuilder()
           .WithUrl("http://localhost:61514/Notify")
          .ConfigureLogging(logging =>
          {
              logging.AddConsole();
              logging.SetMinimumLevel(LogLevel.Debug);
          })
           .Build();

和消息开始流入。