Question

I am trying to create a client signalr app. At present, I am able to get my MVC clients to send messages to and from the Hub, however, I’m facing some difficulties with my .NET client app

Server Hub code:

namespace ServerHub
{
    public class ChatterBox : Hub
    {

        public void Send(string message)
        {
            Clients.All.addMessage(message);
        }
    }
}

Console App code (almost directly lifted from github)

using Microsoft.AspNet.SignalR.Client.Hubs;
using ServerHub;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
          Say("hello from console");
        }
        public static void Say(string message)
        {
            //var connection = new HubConnection("http://localhost/");

            //IHubProxy myHub = connection.CreateHubProxy("ChatterBox");

            var connection = new HubConnection("http://localhost/");
            //Make proxy to hub based on hub name on server
            var myHub = connection.CreateHubProxy("ChatterBox");
            //Start connection
            connection.Start().ContinueWith(task =>
            {
                if (task.IsFaulted)
                {
                    Console.WriteLine("Failed to start: {0}", task.Exception.GetBaseException());
                }
                else
                {
                    Console.WriteLine("Success! Connected with client connection id {0}", connection.ConnectionId);
                    // Do more stuff here
                }
            });

            connection.Send("Hello").ContinueWith(task =>
            {
                if (task.IsFaulted)
                {
                    Console.WriteLine("Send failed {0}", task.Exception.GetBaseException());
                }
                else
                {
                    Console.WriteLine("Success");
                }
            });
        }
    }
}

I get the error message below, during connection.Send()

Start must be called before data can be sent.

Where did I go wrong?

EDIT:

2nd attempt:

    var connection = new HubConnection("http://localhost/");
    //Make proxy to hub based on hub name on server
    var myHub = connection.CreateHubProxy("ChatterBox");
    //Start connection
    connection.Start().ContinueWith(task =>
        {
            if (task.IsFaulted)
            {
                Console.WriteLine("Failed to start: {0}", task.Exception.GetBaseException());
            }
            else
            {
                Console.WriteLine("Success! Connected with client connection id {0}",
                                  connection.ConnectionId);

                // Do more stuff here

                connection.Send("Hello");
            }
        });


    myHub.Invoke("Send", "lol");

Still gives me an error

EDIT: 3rd Attempt

            var connection = new HubConnection("http://localhost:60610/");
            //Make proxy to hub based on hub name on server
            var myHub = connection.CreateHubProxy("ChatterBox");
            //Start connection
            connection.Start().ContinueWith(task =>
            {
                if (task.IsFaulted)
                {
                    Console.WriteLine("Failed to start: {0}", task.Exception.GetBaseException());
                }
                else
                {
                    //Console.WriteLine("Success! Connected with client connection id {0}", connection.ConnectionId);

                    myHub.Invoke("Send", "lol");
                }
            });

Seems to be working

I also needed to set the port number – e.g., if I’m browsing my MVC website like this: http://localhost:60610/, this is the address I need to set in my console app.

Can I say that during deployment, it won’t be an issue because it’ll be port 80 by default?

Answer 1

Read this http://msdn.microsoft.com/en-us/library/dd460717.aspx

TL;DR Start is async and that’s not how you write sequential asynchronous code:

    var connection = new HubConnection("http://localhost/");
    //Make proxy to hub based on hub name on server
    var myHub = connection.CreateHubProxy("ChatterBox");
    //Start connection
    connection.Start().ContinueWith(task =>
    {
        if (task.IsFaulted)
        {
            Console.WriteLine("Failed to start: {0}", task.Exception.GetBaseException());
        }
        else
        {
            Console.WriteLine("Success! Connected with client connection id {0}", connection.ConnectionId);

            // Do more stuff here

            connection.Send("Hello").ContinueWith(task =>
            {
                 .......
            });
        }
    });

If you can use .NET 4.5 it’ll make your life alot easier:

var connection = new HubConnection("http://localhost/");
//Make proxy to hub based on hub name on server
var myHub = connection.CreateHubProxy("ChatterBox");
//Start connection
try 
{
    await connection.Start();
    Console.WriteLine("Success! Connected with client connection id {0}", connection.ConnectionId);
}
catch(Exception ex) 
{
    Console.WriteLine("Failed to start: {0}", ex.GetBaseException());
}

await connection.Send("Hello");

UPDATE: Let’s try this again. The code below will work but you should really read that link to learn how to write async code. Otherwise you’ll just run into these problems over and over.

var connection = new HubConnection("http://localhost/");
//Make proxy to hub based on hub name on server
var myHub = connection.CreateHubProxy("ChatterBox");
//Start connection
connection.Start().ContinueWith(task =>
    {
        if (task.IsFaulted)
        {
            Console.WriteLine("Failed to start: {0}", task.Exception.GetBaseException());
        }
        else
        {
            Console.WriteLine("Success! Connected with client connection id {0}",
                              connection.ConnectionId);

            myHub.Invoke("Send", "lol");
        }
    });