SignalR Console app example

Question

Is there a small example of a console or winform app using signalR to send a message to a .net hub?. I have tried the .net examples and have looked at the wiki but it is not making sense to me the relationship between the hub(.net) and client(console app) (could not find an example of this). Does the app just need the address and name of hub to connect?.

If someone could provide a small tidbit of code showing the app connecting to a hub and sending "Hello World" or something that the .net hub receives?.

PS. I have a standard hub chat example which works well , if I try to assign a hub name in Cs to it , it stops working i.e [HubName("test")] , do you know the reason for this?.

Thanks.

Current Console app Code.

static void Main(string[] args)
{
    //Set connection
    var connection = new HubConnection("http://localhost:41627/");
    //Make proxy to hub based on hub name on server
    var myHub = connection.CreateProxy("chat");
    //Start connection
    connection.Start().ContinueWith(task =>
    {
        if (task.IsFaulted)
        {
            Console.WriteLine("There was an error opening the connection:{0}", task.Exception.GetBaseException());
        }
        else
        {
            Console.WriteLine("Connected");
        }
    }).Wait();

    //connection.StateChanged += connection_StateChanged;

    myHub.Invoke("Send", "HELLO World ").ContinueWith(task => {
        if(task.IsFaulted)
        {
            Console.WriteLine("There was an error calling send: {0}",task.Exception.GetBaseException());
        }
        else
        {
            Console.WriteLine("Send Complete.");
        }
    });
 }

Hub Server. (different project workspace)

public class Chat : Hub
{
    public void Send(string message)
    {
        // Call the addMessage method on all clients
        Clients.addMessage(message);
    }
}

Info Wiki for this is http://www.asp.net/signalr/overview/signalr-20/hubs-api/hubs-api-guide-net-client

Rosenberg

O.K actually this actually worked just thought I was getting the same result just added some stop points and Console.ReadLine(); at the end. Whoop!. – Rosenberg

Answer 1

First of all, you should install SignalR.Host.Self on the server application and SignalR.Client on your client application by nuget :

PM> Install-Package SignalR.Hosting.Self -Version 0.5.2

PM> Install-Package Microsoft.AspNet.SignalR.Client

Then add the following code to your projects ;)

(run the projects as administrator)

Server console app:

using System;
using SignalR.Hubs;

namespace SignalR.Hosting.Self.Samples {
    class Program {
        static void Main(string[] args) {
            string url = "http://127.0.0.1:8088/";
            var server = new Server(url);

            // Map the default hub url (/signalr)
            server.MapHubs();

            // Start the server
            server.Start();

            Console.WriteLine("Server running on {0}", url);

            // Keep going until somebody hits 'x'
            while (true) {
                ConsoleKeyInfo ki = Console.ReadKey(true);
                if (ki.Key == ConsoleKey.X) {
                    break;
                }
            }
        }

        [HubName("CustomHub")]
        public class MyHub : Hub {
            public string Send(string message) {
                return message;
            }

            public void DoSomething(string param) {
                Clients.addMessage(param);
            }
        }
    }
}

Client console app:

using System;
using SignalR.Client.Hubs;

namespace SignalRConsoleApp {
    internal class Program {
        private static void Main(string[] args) {
            //Set connection
            var connection = new HubConnection("http://127.0.0.1:8088/");
            //Make proxy to hub based on hub name on server
            var myHub = connection.CreateHubProxy("CustomHub");
            //Start connection

            connection.Start().ContinueWith(task => {
                if (task.IsFaulted) {
                    Console.WriteLine("There was an error opening the connection:{0}",
                                      task.Exception.GetBaseException());
                } else {
                    Console.WriteLine("Connected");
                }

            }).Wait();

            myHub.Invoke<string>("Send", "HELLO World ").ContinueWith(task => {
                if (task.IsFaulted) {
                    Console.WriteLine("There was an error calling send: {0}",
                                      task.Exception.GetBaseException());
                } else {
                    Console.WriteLine(task.Result);
                }
            });

            myHub.On<string>("addMessage", param => {
                Console.WriteLine(param);
            });

            myHub.Invoke<string>("DoSomething", "I'm doing something!!!").Wait();


            Console.Read();
            connection.Stop();
        }
    }
}

Dissertation

You can use the above code in windows application but is it really necessary?! Im not sure what you mean, you can notify in windows in other ways. – Dissertation

client works with server 0.5.2 upto 1.0.0-alpha2 e.g. Install-Package Microsoft.AspNet.SignalR.Client -version 1.0.0-alpha2 nuget.org/packages/Microsoft.AspNet.SignalR.Client/1.0.0-alpha2 (code and SignalR versions should work with .net 4.0 using VS2010 SP1) been trying to work out why I couldn't get it to work, eventually tried the client with SignalR early versions. – Graubert

nice, really helpfull – Lambkin

Note you must add the event listeners (the.On<T>() method calls) before calling the connection.Start() method. – Loiseloiter

It deserves to provide this link: learn.microsoft.com/en-us/aspnet/signalr/overview/… – Marciemarcile

Answer 2

Example for SignalR 2.2.1 (May 2017)

Server

Install-Package Microsoft.AspNet.SignalR.SelfHost -Version 2.2.1

[assembly: OwinStartup(typeof(Program.Startup))]
namespace ConsoleApplication116_SignalRServer
{
    class Program
    {
        static IDisposable SignalR;

        static void Main(string[] args)
        {
            string url = "http://127.0.0.1:8088";
            SignalR = WebApp.Start(url);

            Console.ReadKey();
        }

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

                /*  CAMEL CASE & JSON DATE FORMATTING
                 use SignalRContractResolver from
                https://mcmap.net/q/196002/-signalr-use-camel-case

                var settings = new JsonSerializerSettings()
                {
                    DateFormatHandling = DateFormatHandling.IsoDateFormat,
                    DateTimeZoneHandling = DateTimeZoneHandling.Utc
                };

                settings.ContractResolver = new SignalRContractResolver();
                var serializer = JsonSerializer.Create(settings);
                  
               GlobalHost.DependencyResolver.Register(typeof(JsonSerializer),  () => serializer);                
            
                 */

                app.MapSignalR();
            }
        }

        [HubName("MyHub")]
        public class MyHub : Hub
        {
            public void Send(string name, string message)
            {
                Clients.All.addMessage(name, message);
            }
        }
    }
}

Client

(almost the same as Mehrdad Bahrainy reply)

Install-Package Microsoft.AspNet.SignalR.Client -Version 2.2.1

namespace ConsoleApplication116_SignalRClient
{
    class Program
    {
        private static void Main(string[] args)
        {
            var connection = new HubConnection("http://127.0.0.1:8088/");
            var myHub = connection.CreateHubProxy("MyHub");

            Console.WriteLine("Enter your name");    
            string name = Console.ReadLine();

            connection.Start().ContinueWith(task => {
                if (task.IsFaulted)
                {
                    Console.WriteLine("There was an error opening the connection:{0}", task.Exception.GetBaseException());
                }
                else
                {
                    Console.WriteLine("Connected");

                    myHub.On<string, string>("addMessage", (s1, s2) => {
                        Console.WriteLine(s1 + ": " + s2);
                    });

                    while (true)
                    {
                        Console.WriteLine("Please Enter Message");
                        string message = Console.ReadLine();

                        if (string.IsNullOrEmpty(message))
                        {
                            break;
                        }

                        myHub.Invoke<string>("Send", name, message).ContinueWith(task1 => {
                            if (task1.IsFaulted)
                            {
                                Console.WriteLine("There was an error calling send: {0}", task1.Exception.GetBaseException());
                            }
                            else
                            {
                                Console.WriteLine(task1.Result);
                            }
                        });
                    }
                }

            }).Wait();

            Console.Read();
            connection.Stop();
        }
    }
}

Piegari

Doesn't work for me... throws a null ref exception at WebApp.Start() – Gasper

Maybe by any chance, you now how to set json serialization settings (eg camelCase) globally in this self hosted signalr server? – Gissing

@XarisFytrakis super easy, Ive updates the anwser, you need contract resolver from here: https://mcmap.net/q/196002/-signalr-use-camel-case as well as DateFormatHandling = DateFormatHandling.IsoDateFormat, if you consume it from js. – Piegari

@ADOConnection Thanks for the quick reply. The problem now is when calling method from a .net client. For example if I in the Hub class, call this: HubContext.Clients.All.UpdateMetric(new { Data = "xxx", Something = "yyy"}, username); I get json response with the correct serialization settings (Camel Cased). But if I call it with passed data from a client (asp.net client) like this: public void UpdateMetric(object metrics, string username) { HubContext.Clients.All.UpdateMetric(metrics, username); the result on client is not Camel Cased. – Gissing

Answer 3

To build on @dyslexicanaboko's answer for dotnet core, here is a client console application:

Create a helper class:

using System;
using Microsoft.AspNetCore.SignalR.Client;

namespace com.stackoverflow.SignalRClientConsoleApp
{
    public class SignalRConnection
    {
        public async Task Start()
        {
            var url = "http://signalr-server-url/hubname";

            var connection = new HubConnectionBuilder()
                .WithUrl(url)
                .WithAutomaticReconnect()
                .Build();

            // receive a message from the hub
            connection.On<string, string>("ReceiveMessage", OnReceiveMessage);

            await connection.StartAsync();

            // send a message to the hub
            await connection.InvokeAsync("SendMessage", "ConsoleApp", "Message from the console app");
        }

        private void OnReceiveMessage(string user, string message)
        {
            Console.WriteLine($"{user}: {message}");
        }

    }
}

Then implement in your console app's entry point:

using System;

namespace com.stackoverflow.SignalRClientConsoleApp
{
    class Program
    {
        static void Main(string[] args)
        {
            var signalRConnection = new SignalRConnection();
            signalRConnection.Start();

            Console.Read();
        }
    }
}

Tamar

Your answer has greatly helped me, but lol using java-like namespaces on a modern platform. – Grosz

@FedericoBerasategui Lol, I always thought the java namespace convention is well structured and thought why Microsoft did not adapt the same. Did some reading, I never realized it was just an old thing. Thanks for the heads up. – Tamar

Answer 4

The Self-Host now uses Owin. Checkout http://www.asp.net/signalr/overview/signalr-20/getting-started-with-signalr-20/tutorial-signalr-20-self-host to setup the server. It's compatible with the client code above.

Ubangi

Answer 5

This is for dot net core 2.1 - after a lot of trial and error I finally got this to work flawlessly:

var url = "Hub URL goes here";

var connection = new HubConnectionBuilder()
    .WithUrl($"{url}")
    .WithAutomaticReconnect() //I don't think this is totally required, but can't hurt either
    .Build();

//Start the connection
var t = connection.StartAsync();

//Wait for the connection to complete
t.Wait();

//Make your call - but in this case don't wait for a response 
//if your goal is to set it and forget it
await connection.InvokeAsync("SendMessage", "User-Server", "Message from the server");

This code is from your typical SignalR poor man's chat client. The problem that I and what seems like a lot of other people have run into is establishing a connection before attempting to send a message to the hub. This is critical, so it is important to wait for the asynchronous task to complete - which means we are making it synchronous by waiting for the task to complete.

Timmytimocracy

you could actually chain the start and wait as connection.StartAsync.Wait() – Gout