C# – SignalR .NET Client – Unexpected character encountered while parsing value

cnetsignalrsignalr-hubsignalr.client

I'm trying to set up a .NET client to send messages to my SignalR hub from my service layer. I'm following this guide: http://www.asp.net/signalr/overview/signalr-20/hubs-api/hubs-api-guide-net-client#callserver

This is what I have:

        _hubConnection = new HubConnection(_baseUrl); // "http://localhost:3806"
        _hubProxy = _hubConnection.CreateHubProxy("AppHub");
        _hubConnection.Start().Wait();

The hub lives inside of the same project – it's an MVC application with forms authentication.

I can never get past the .Wait() call, it always errors out with the following:

Message=Unexpected character encountered while parsing value: <. Path '', line 0, position 0.
       Source=Newtonsoft.Json

More trace:

at Newtonsoft.Json.JsonConvert.DeserializeObject[T](String value)
at Microsoft.AspNet.SignalR.Client.Transports.TransportHelper.b__1(String
raw)
at Microsoft.AspNet.SignalR.TaskAsyncHelper.<>c__DisplayClass192.<Then>b__17(Task1
t)
at Microsoft.AspNet.SignalR.TaskAsyncHelper.TaskRunners2.<>c__DisplayClass3a.<RunTask>b__39(Task1
t)

I have AppHub:

public class AppHub : Hub { .. }

What am I doing wrong?

Best Answer

Since you are using Forms Authentication and I cannot see that you are providing any credentials when you construct your HubConnection, that might be your problem. This page talks of how to setup a SignalR connection using Forms Authentication: http://www.asp.net/signalr/overview/signalr-20/security/hub-authorization

class Program
    {
    static void Main(string[] args)
    {
        var connection = new HubConnection("http://www.contoso.com/");
        Cookie returnedCookie;

        Console.Write("Enter user name: ");
        string username = Console.ReadLine();

        Console.Write("Enter password: ");
        string password = Console.ReadLine();

        var authResult = AuthenticateUser(username, password, out returnedCookie);

        if (authResult)
        {
            connection.CookieContainer = new CookieContainer();
            connection.CookieContainer.Add(returnedCookie);
            Console.WriteLine("Welcome " + username);
        }
        else
        {
            Console.WriteLine("Login failed");
        }    
    }

    private static bool AuthenticateUser(string user, string password, out Cookie authCookie)
    {
        var request = WebRequest.Create("https://www.contoso.com/RemoteLogin") as HttpWebRequest;
        request.Method = "POST";
        request.ContentType = "application/x-www-form-urlencoded";
        request.CookieContainer = new CookieContainer();

        var authCredentials = "UserName=" + user + "&Password=" + password;
        byte[] bytes = System.Text.Encoding.UTF8.GetBytes(authCredentials);
        request.ContentLength = bytes.Length;
        using (var requestStream = request.GetRequestStream())
        {
            requestStream.Write(bytes, 0, bytes.Length);
        }

        using (var response = request.GetResponse() as HttpWebResponse)
        {
            authCookie = response.Cookies[FormsAuthentication.FormsCookieName];
        }

        if (authCookie != null)
        {
            return true;
        }
        else
        {
            return false;
        }
    }
}

RemoteLogin page:

using System;
using System.Web.Security;

namespace SignalRWithConsoleChat
{
    public partial class RemoteLogin : System.Web.UI.Page
    {
        protected void Page_Load(object sender, EventArgs e)
        {
            string username = Request["UserName"];
            string password = Request["Password"];
            bool result = Membership.ValidateUser(username, password);
            if (result)
            {
                FormsAuthentication.SetAuthCookie(username, false);
            }
        }
    }
}

Related Solutions

C# – SignalR Console app example

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();
        }
    }
}

Passing connection token is secure or hacky from signalr js client side to hub function

You can use headers in the javascript client like this for example:

$.signalR.ajaxDefaults.headers = { Authorization: "Bearer " + yourToken };

Now not hacky and is a global setting you can do once at startup or successful auth response! Enjoy!

Now only if I can find a way to override this on a per-request basis so I can get a user emulation sandbox working for my users in administrative roles...

Best Answer

Related Solutions

C# – SignalR Console app example

Passing connection token is secure or hacky from signalr js client side to hub function

Related Topic