SignalR .NET client works in console app but not in a windows service

Question

Here's my SignalR console app which works fine. It's able to receive messages from the Hub and print them onto the console.

    static void Main(string[] args)
    {

        MainAsync().Wait();
        Console.ReadLine();
    }

    static async Task MainAsync()
    {
        try
        {

            var hubConnection = new HubConnection("http://localhost:8080/");
            IHubProxy hubProxy = hubConnection.CreateHubProxy("MyHub");
            hubProxy.On<string, string>("addMessage", (name, message) =>
            {
                Console.WriteLine("Incoming data: {0} {1}", name, message);
            });
            ServicePointManager.DefaultConnectionLimit = 10;
            await hubConnection.Start();

        }
        catch (Exception ex)
        {

        }
    }

I created a windows service, and copied almost character for character, except the part where it prints to the console, I printed it to a log file

    protected override void OnStart(string[] args)
    {
            Log.Info("Starting...");
            StartListening().Wait();
    }

    private static async Task StartListening()
    {
        try
        {
            var hubConnection = new HubConnection("http://localhost:8080/");
            IHubProxy hubProxy = hubConnection.CreateHubProxy("MyHub");
            hubProxy.On<string, string>("addMessage", (name, message) =>
            {
                Log.Info(string.Format("Incoming data: {0} {1}", name, message));
            });
            ServicePointManager.DefaultConnectionLimit = 10;
            await hubConnection.Start();
            Log.Info("Connected");
        }
        catch (Exception ex)
        {
            Log.Error(ex);
        }
    }

Here's my server code:

    static void Main(string[] args)
    {
        //string url = "http://localhost:8080";
        string url = "http://*:8080";
        using (WebApp.Start(url))
        {
            MyHub hub = new MyHub();
            Console.WriteLine("Server running on {0}", url);
            var key = Console.ReadLine();
            while (key != "quit")
            {
                hub.Send("Server", key);
            }
        }
    }

public class Startup
{
    public void Configuration(IAppBuilder app)
    {
        app.UseCors(CorsOptions.AllowAll);
        app.MapSignalR();
    }
}

public class MyHub : Hub
{
    public void Send(string name, string message)
    {
        //Clients.All.addMessage(name, message);
        var context = GlobalHost.ConnectionManager.GetHubContext<MyHub>();
        context.Clients.All.addMessage(name, message);
    }
}

However, nothing gets written to the log file except "Starting..." and "Connected"

There were no exceptions thrown either.

Do I need to include anything else or modify the code for SignalR to work on a windows service?

Update

Apparently, it seemed that changing this line

string url = "http://localhost:8080";

to this

string url = "http://*:8080";

in my server code solved my issue. But I don't know why.

Answer 1

I had a similar issue. The problem was using localhost in the URL. Replace localhost with the actual server name.

The issue is explained here.

The URL is used to open an HttpListener. With the URL above (the localhost one) this HttpListener will accept requests from http://localhost only. Other, equivalent URLs do not work:

http://127.0.0.1
http://110.120.130.140
http://myserver