Using the new signalR for DotNet core to send messages from console App to web page

Question

I am using this example from https://blogs.msdn.microsoft.com/webdev/2017/09/14/announcing-signalr-for-asp-net-core-2-0/ to create a console app that can send messages from a simple console app to a web page.

Below is the simple example for console application which reads the user input and prints that input on the screen, I want to send the same user input also to the web page.

static void Main(string[] args)
        {
            while (true)
            {
                Console.WriteLine("Enter input:");
                string line = Console.ReadLine();
                if (line == "exit")
                {
                    break;
                }
                sendSignalToClient(line);
                Console.Write("Message Sent To Client: " + line);
            }
        }

        private static void sendSignalToClient(string line)
        {
            //Send a message from this app to web client using signalR
        }

I have just started learning about this. Any material or suggestions related to this is appreciated. -Thanks

Edit: I am using a sample signalR chat application.

public class Program
    {
        public static void Main(string[] args)
        {
            BuildWebHost(args).Run();
        }

        public static IWebHost BuildWebHost(string[] args) =>
            WebHost.CreateDefaultBuilder(args)
                .UseStartup<Startup>()
                .Build();
    }

public class ChatHub : Hub
    {
        public void Send(string name, string message)
        {
            // Call the broadcastMessage method to update clients.
            Clients.All.InvokeAsync("broadcastMessage", name, message);
        }
    }

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

        public void Configure(IApplicationBuilder app, IHostingEnvironment env)
        {
            if (env.IsDevelopment())
            {
                app.UseDeveloperExceptionPage();
            }
            app.UseFileServer();

            app.UseSignalR(routes =>
            {
                routes.MapHub<ChatHub>("chat");
            });
        }

Below is the code for the console application that is sending messages to web page

class Program : Hub
{
    static void Main(string[] args)
    {
        Task.Run(Run).Wait();
    }

    static async Task Run()
    {
        var connection = new HubConnectionBuilder()
            .WithUrl("http://localhost:59768/chat")
            .WithConsoleLogger()
            .WithMessagePackProtocol()
            .WithTransport(TransportType.WebSockets)
            .Build();

        await connection.StartAsync();

        Console.WriteLine("Starting connection. Press Ctrl-C to close.");
        var cts = new CancellationTokenSource();
        Console.CancelKeyPress += (sender, a) =>
        {
            a.Cancel = true;
            cts.Cancel();
        };

        connection.Closed += e =>
        {
            Console.WriteLine("Connection closed with error: {0}", e);

            cts.Cancel();
            return Task.CompletedTask;
        };

        connection.On("broadcastMessage", async () =>
        {


        });

        while (true)
        {
            Thread.Sleep(2000);

            await connection.SendAsync("send", "alex", "hello");

        }
    }

All the code is working but on the console application i am receiving this exception:

 Microsoft.AspNetCore.Sockets.Client.HttpConnection[19]
      09/17/2017 13:47:17: Connection Id 40da6d4b-9c47-4831-802f-628bbb172e10: An exception was thrown from the 'Received' event handler.
System.FormatException: Target method expects 0 arguments(s) but invocation has 2 argument(s).
   at Microsoft.AspNetCore.SignalR.Internal.Protocol.MessagePackHubProtocol.CreateInvocationMessage(Unpacker unpacker, IInvocationBinder binder)
   at Microsoft.AspNetCore.SignalR.Internal.Protocol.MessagePackHubProtocol.TryParseMessages(ReadOnlyBuffer`1 input, IInvocationBinder binder, IList`1& messages)
   at Microsoft.AspNetCore.SignalR.Internal.HubProtocolReaderWriter.ReadMessages(Byte[] input, IInvocationBinder binder, IList`1& messages)
   at Microsoft.AspNetCore.SignalR.Client.HubConnection.<OnDataReceivedAsync>d__31.MoveNext()
--- End of stack trace from previous location where exception was thrown ---
   at System.Runtime.ExceptionServices.ExceptionDispatchInfo.Throw()
   at System.Runtime.CompilerServices.TaskAwaiter.HandleNonSuccessAndDebuggerNotification(Task task)
   at Microsoft.AspNetCore.Sockets.Client.HttpConnection.<>c__DisplayClass49_0.<<ReceiveAsync>b__0>d.MoveNext()

Answer 1

Your event handler should take a string argument, it should look like this:

connection.On<string>("broadcastMessage", data =>
{

});