SignalR 不适用于 .net 内核 WPF 应用程序

Question

I'm working on a .net core application that will use SignalR for communication between server and clients. It seems that .net core WPF client is not able to start a connection with the server. After reaching StartAsync method it hangs without any information. Here is a sample code for that. I have prepared also a console client which is using the same way for connecting to the server and it is working properly. Could anyone have encountered similar problems?

Answer 1

It's dead-locked. Do not use .Wait() in a UI synchronization context.

Incase of link-rot, here is the code you posted:

namespace Communication
{
    public class LiveService
    {
        private readonly HubConnection _hubConnection;
        public LiveService()
        {
            var hubConnectionBuilder = new HubConnectionBuilder();
            _hubConnection = hubConnectionBuilder
                .WithUrl("https://localhost:5001/signalrTestHub/")
                .Build();

            _hubConnection.StartAsync(default).Wait();
         }

        public async Task Send(CancellationToken cancellationToken = default)
        {
            await _hubConnection.SendAsync("SendTestMsg", "Test value", cancellationToken);
        }
    }
}

This is an example on how to fix it:

namespace Communication
{
    public class LiveService
    {
        private readonly HubConnection _hubConnection;
        private readonly Task _initialized;

        public LiveService()
        {
            var hubConnectionBuilder = new HubConnectionBuilder();

            _hubConnection = hubConnectionBuilder
                .WithUrl("https://localhost:5001/signalrTestHub/")
                .Build();

            _initialized = _hubConnection.StartAsync(default);
        }

        public async Task Send(CancellationToken cancellationToken = default)
        {
            await _initialized;
            await _hubConnection.SendAsync("SendTestMsg", "Test value", cancellationToken);
        }
    }
}