调用 SignalR Hub 不适用于 Asp.Net Core Web API [英] Invoking SignalR Hub not working for Asp.Net Core Web API

问题描述

我是 SignalR 的新手.我正在尝试设置一个 Asp.Net Core WebAPI，以便其他客户端可以使用 SignalR 连接到它并获取实时数据.我的 Hub 类是:

I'm a newb to SignalR. I'm trying to set up a Asp.Net Core WebAPI so that other clients can connect to it using SignalR and get real-time data. My Hub class is:

public class TimeHub : Hub
{
    public async Task UpdateTime(string message)
    {
        await Clients.All.SendAsync("ReceiveMessage", message);
    }
}

我有一个中继类如下:

public class TimeRelay : ITimeRelay
{
    private readonly IHubContext<TimeHub> _timeHubContext;

    public TimeRelay(IHubContext<TimeHub> context)
    {

        _timeHubContext = context;
        Task.Factory.StartNew(async () =>
        {
            while (true)
            {
                await context.Clients.All.SendAsync("UpdateTime", DateTime.Now.ToShortDateString());
                Thread.Sleep(2000);
            }
        });
    }
}

启动类:

public void ConfigureServices(IServiceCollection services)
{
    services.AddMvc().SetCompatibilityVersion(CompatibilityVersion.Version_2_1);

    services.AddSignalR();
}

public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    app.UseDeveloperExceptionPage();

    app.UseHttpsRedirection();

    app.UseSignalR((x) =>
    {
        x.MapHub<TimeHub>("/timeHub");
    });
    app.UseMvc();
}

客户端是一个控制台应用程序，代码是:

The client is a console application and the code is:

class Program
{    
    static Action<string> OnReceivedAction = OnReceived;

    static void Main(string[] args)
    {
        Connect();
        Console.ReadLine();
    }

    private static async void Connect()
    {
        var hubConnectionBuilder = new HubConnectionBuilder();

        var hubConnection = hubConnectionBuilder.WithUrl("http://localhost:60211/timeHub").Build();

        await hubConnection.StartAsync();

        var on = hubConnection.On("ReceiveMessage", OnReceivedAction);

        Console.ReadLine();    
        on.Dispose();
        await hubConnection.StopAsync();
    }

    static void OnReceived(string message)
    {
        System.Console.WriteLine($"{message}");
    }
}

我尝试调试应用程序.客户端成功连接到 TimeHub.当客户端连接时，Clients.All 中的连接数从 0 变为 1.但是，当 await context.Clients.All.SendAsync("UpdateTime", DateTime.Now.ToShortDateString()); 被执行时，TimeHub 中的 UpdateTime 函数 没有被执行，客户端也没有收到任何消息.

I tried debugging the application. The client got connected to the TimeHub succesfully. The no of connections in Clients.All changed from 0 to 1, when the client got connected. But, when await context.Clients.All.SendAsync("UpdateTime", DateTime.Now.ToShortDateString()); is executed, the UpdateTime function in TimeHub is not getting executed and the client is not getting any message.

我尝试使用 "UpdateTime"、"SendMessage" 和 "ReceiveMessage" 作为 Clients.All.SendAsync 中的方法 在 TimeRelay 类中.没有任何效果.有人能指出我在这方面的错误吗.

I tried using "UpdateTime", "SendMessage", and "ReceiveMessage" as method in Clients.All.SendAsync in TimeRelay class. Nothing worked. Could someone point out my mistake in this.

推荐答案

我开始使用它，我想我会在这里回答它.感谢@TaoZhou 的提示.

I got it to work and thought I will answer it here. Thanks @TaoZhou for the tip.

我的错误是从服务器发送UpdateTime"并在客户端等待ReceiveMessage".

My mistake was sending "UpdateTime" from server and waiting on "ReceiveMessage" at the client.

理想情况下，代码应如下所示:

Ideally the code should look like the following:

SignalR 服务器:
await context.Clients.All.SendAsync("UpdateTime", DateTime.Now.ToShortDateString());

SignalR Server:
await context.Clients.All.SendAsync("UpdateTime", DateTime.Now.ToShortDateString());

SignalR 客户端:
var on = hubConnection.On("UpdateTime", OnReceivedAction);

SignalR Client:
var on = hubConnection.On("UpdateTime", OnReceivedAction);

在这种情况下，从服务器发送的任何消息都会立即在客户端收到.
请参阅问题中提供的代码以获取更多信息.

In this case any message send from the server would be received at the client instantly.
Please refer the code provided in the question for more info.

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