Question

我无法连接到在Windows 7下运行的ASP.NET Core 2.0.3应用程序中的SignalR Hub。我使用NuGet的SignalR 1.0.0-alpha1-final作为服务器，将signalr-client-1.0.0-alpha2-final.min.js作为JavaScript客户端使用。

这是我的中心：

using System;
using System.Threading.Tasks;
using Microsoft.AspNetCore.SignalR;

namespace MyProject
{
    public class MyHub: Hub
    {
        public override async Task OnConnectedAsync()
        {
            await Clients.All.InvokeAsync("Send", $"{Context.ConnectionId} joined");
        }

        public Task Send(string message)
        {
            return Clients.All.InvokeAsync("Send", $"{Context.ConnectionId}: {message}");
        }    
    }
}

在startup.cs中配置：

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
        app.UseBrowserLink();
    }
    else
    {
        app.UseExceptionHandler("/Error");
    }

    app.UseStaticFiles();
    app.UseHangfireDashboard();
    app.UseHangfireServer();

    app.UseSignalR(routes =>
    {
        routes.MapHub<MyHub>("hubs");
    });

    app.UseMvc(routes =>
    {
        routes.MapRoute(
            name: "default",
            template: "{controller}/{action=Index}/{id?}");
    });
}

并在测试页面中：

let transportType = signalR.TransportType[getParameterByName('transport')] || signalR.TransportType.WebSockets;
let http = new signalR.HttpConnection(`http://${document.location.host}/hubs`, { transport: transportType });
var connection = new signalR.HubConnection(http);

但是当执行此代码时，我从服务器收到错误204。

更新

根据@Gabriel Luci的答案，这里是工作代码：

let transportType = signalR.TransportType.LongPolling;
let http = new signalR.HttpConnection(`http://${document.location.host}/hubs`, { transport: transportType });
let connection = new signalR.HubConnection(http);

connection.start();

connection.on('Send', (message) => {
    console.log(message);
});

...
connection.invoke('Echo', "Hello ");

Answer 1

GitHub提出了一个问题：https://github.com/aspnet/SignalR/issues/1028

显然，WebSockets在IIS和IIS Express中不起作用。你需要使用长轮询。该问题中有一小段示例代码：

let connection = new HubConnection("someurl", { transport: signalR.TransportType.LongPolling });
connection.start().then(() => {});

Answer 2

就我而言，我必须删除允许的任何来源并将其替换为WithOrigins和AllowCredentials

 options.AddPolicy("policy",
            builder =>
            {
                builder.WithOrigins("http://localhost:8081");
                builder.AllowAnyMethod();
                builder.AllowAnyHeader();
                builder.AllowCredentials();

            });

尝试连接SignalR时出错204

更新

2 个答案: