How can I kill a SignalR connection?

Question

I am using SignalR to transfer data on a website. But SignalR should only be able to send data for a period of time and if the time period has passed the connection should be killed.

The Stop-Function $.connection.hub.stop() is cancelled if a request is still pending and is not completed. But this request should be forced to cancel no matter how much data has been sent.

How can I kill a SignalR-Connection?

Answer 1

As you can see in this Microsoft Documentation about Timeout and keepalive settings you can define the DisconnectTimeout in the options.

Example:

protected void Application_Start(object sender, EventArgs e)
{
    // Make long-polling connections wait a maximum of 110 seconds for a
    // response. When that time expires, trigger a timeout command and
    // make the client reconnect.
    GlobalHost.Configuration.ConnectionTimeout = TimeSpan.FromSeconds(110);

    // Wait a maximum of 30 seconds after a transport connection is lost
    // before raising the Disconnected event to terminate the SignalR connection.
    GlobalHost.Configuration.DisconnectTimeout = TimeSpan.FromSeconds(30);

    // For transports other than long polling, send a keepalive packet every
    // 10 seconds. 
    // This value must be no more than 1/3 of the DisconnectTimeout value.
    GlobalHost.Configuration.KeepAlive = TimeSpan.FromSeconds(10);

    RouteTable.Routes.MapHubs();
}

Edit : Since you want to kill the connection from the client no matter what, you are talking about a CancellationToken behavior but unfortunately this is still not supported in SignalR as you can see here and here , the team wants to do that to SignalR but still there is no news about it.

Answer 2

Please read this microsoft document about Hub lifetime event. You can change the default values for these settings, set them in Application_Start in your Global.asax file. But this way you can't full control client side. So you use javascript setTimeout function and pass the time form server end when a new user connect.it's may be GlobalHost.Configuration.DisconnectTimeout or any time you want. I give a full example with demo project. Actually i use this logic in a very large ticketing system for real-time holding ticket. (please read all inline comment)

Model:

public class MyModel
{
    public int Id { get; set; }

    public string Name { get; set; }


    public static string Send(MyModel my)
    {
        //Do Somthing           
        return $"Data Sending to {my.Name}...";
    }
    public static string Stop(string name)
    {
        //Do Somthing

        return $"ForceStop {name}.";
    }
    public static string Delete()
    {
        //Do Somthing

        return "Deleted";
    }
}

Hub:

[HubName("myHub")]
public class MyHub : Hub
{
    int connectionTimeOut = 10;//sec

    [HubMethodName("connect")]
    public void Connect()
    {  
            //apply logic if any when user connected or reload page
            //set connection Time Out as you need
        connectionTimeOut= 10;// GlobalHost.Configuration.DisconnectTimeout

       Clients.Client(Context.ConnectionId).onNewUserConnected(connectionTimeOut);
    }
    [HubMethodName("startSendingServer")]
    public void StartSending(int id, string name)//pass anything you need
    {
        //apply logic if any when start sending data

        var my = new MyModel
        {
            Id = id,
            Name = name
        };
        var status = MyModel.Send(my);//example

        var result = new
        {
            status,
            name
        };

        Clients.Client(Context.ConnectionId).startSendingClient(result);

    }

    [HubMethodName("forceStopServer")]
    public void ForceStop(string name)//pass anything you need
    {
        //apply logic if any when force stop sending data
        var status = MyModel.Stop(name);
        Clients.Client(Context.ConnectionId).forceStopClint(status);
    }


    public override Task OnDisconnected(bool stopCalled)
    {

        //apply logic if any when connection Disconnected

        var status = MyModel.Delete();//example
        if (stopCalled)
        {
            //  status=String.Format("Client {0} explicitly closed the connection.", Context.ConnectionId)
            //your code here
        }
        else
        {
            // status=String.Format("Client {0} timed out .", Context.ConnectionId);
            //your code here
            //Clients.Client(Context.ConnectionId).onUserDisconnected(status);
        }

        return base.OnDisconnected(stopCalled);
    }


}

TestView:

<div class="row">
    <div class="col-md-12">
        <h1> Status: <span id="hubStatus"></span></h1>
        <br />
        <h4> Countdown : <span id="counter"></span></h4>
        <br />

        <button id="btnHub" class="btn btn-primary btn-lg">Start Sending Data</button>
    </div>
</div>
@section scripts{
    <script src="~/Scripts/app/hub.js"></script>
}

hub.js:

var proxyTimer = null;
var sendTimeLimit = 1;//sec
var sessionTime = sendTimeLimit * 1000;

$(function () {
    var myProxy = $.connection.myHub;
    $.connection.hub.start().done(function () {
        registerServerEvents(myProxy);
    });

    clientMethods(myProxy);
});

function registerServerEvents(proxyHub) {
    proxyHub.server.connect();
    $(document).on("click", "#btnHub", function (e) {

        $("#hubStatus").html("Sending..");
        $("#btnHub").text("Count Down Start...");

        //Logic Before start sending data.
        var id = 1;
        var name = "AzR";        
        proxyHub.server.startSendingServer(id,name);

       // $.connection.hub.disconnected(function () {
      //  setTimeout(function () { $.connection.hub.start(); }, 5000); // Restart connection after 5 seconds.
       //});

        $.connection.hub.disconnected(function () {
            $("#hubStatus").html("Disconnected");// you can restart on here.     
            $("#btnHub").text("Stat Again after reload window");

        });

    });
}



function clientMethods(proxyHub) {

    //proxyHub.on('onConnected', function (sendTimeLimit) {
    //    sendTimeLimit = sendTimeLimit;
    //});

    proxyHub.on('onNewUserConnected', function (serverItem) {
        sendTimeLimit = serverItem;
        sessionTime = sendTimeLimit * 1000;
    });


    proxyHub.on('startSendingClient', function (serverItem) {

        //Logic after start sending data.
        var name = serverItem.name;
        var status = serverItem.status;
        $("#hubStatus").html(status);
        $("#counter").html(sendTimeLimit);
        timeCounter();
        startTimer(proxyHub, name );
    });

    proxyHub.on('forceStopClint', function (serverItem) {


        clearClintPendingTask(serverItem);//Logic before proxy stop.
        $("#btnHub").text("Force Stop...");
        $.connection.hub.stop();
    });

    proxyHub.on('onUserDisconnected', function (serverItem) {
        //Logic after proxy Disconnected (time out).
        $("#hubStatus").html(serverItem);
        $("#btnHub").text("Stat Again after reload window");
   });
}

//Logic before proxy stop.
function clearClintPendingTask(status) {
    //do all you need
    $("#hubStatus").html(status); 
    stopTimer();
}

function startTimer(proxyHub,data) {
    stopTimer();
    proxyTimer = setTimeout(function () {
        proxyHub.server.forceStopServer(data);
    }, sessionTime);
}

function stopTimer() {
    if (proxyTimer) {
        clearTimeout(proxyTimer);
        proxyTimer = null;
    }
}

function timeCounter() {
    var counter = sendTimeLimit;
    var interval = setInterval(function () {
        counter--;
        $("#counter").html(counter);
        if (counter == 0) {
            //Do something
            $("#counter").html("Countdown ended!");
            // Stop the counter
            clearInterval(interval);
        }
    }, 1000);
}

(Tested)

Answer 3

You need to define a timeout. On the server you can set DisconnectTimeout, like this:

GlobalHost.Configuration.DisconnectTimeout = TimeSpan.FromMinutes(30);

https://zzz.buzz/2016/05/11/setting-timeout-for-signalr-for-easier-debugging/

Answer 4

Updated Edit, please see Option 3 below. All the others are relying on timeout, I posted a forced disconnect.

If you are trying a Force Disconnect -- you can get the list of the Connected Users and call the ForceLogOut Function on the server side, I saw this somewhere on code project, I hope it helps. If you only want to forceLogout/kill some of the users, just loop through and kill that connection only.

Server Side

---

public class User
{
    public string Name { get; set; }
    public HashSet<string> ConnectionIds { get; set; }
}

---

public class ExtendedHub : Hub
{        
   private static readonly ConcurrentDictionary<string, User> ActiveUsers  = 
      new ConcurrentDictionary<string, User>(StringComparer.InvariantCultureIgnoreCase);
    public IEnumerable<string> GetConnectedUsers()
    {
        return ActiveUsers.Where(x => {

            lock (x.Value.ConnectionIds)
            {
                return !x.Value.ConnectionIds.Contains
                        (Context.ConnectionId, StringComparer.InvariantCultureIgnoreCase);
            }

        }).Select(x => x.Key);
    }           

    public void forceLogOut(string to)
    {
        User receiver;
        if (ActiveUsers.TryGetValue(to, out receiver))
        {
            IEnumerable<string> allReceivers;
            lock (receiver.ConnectionIds)
            {
                allReceivers = receiver.ConnectionIds.Concat(receiver.ConnectionIds);      
            }

            foreach (var cid in allReceivers)
            {
             // ***************** log out/KILL connection for whom ever your want here
                Clients.Client(cid).Signout();
            }
        }
    }
}

---

Client Side

 // 1- Save your connection variable when you start it, and later on you can use it to stop.
var myHubProxy = $.connection.myHub 
// 2- Use it when you need to stop it, IF NOT YOU WILL GET AN ERROR
myHubProxy.client.stopClient = function() {
    $.connection.hub.stop();
};

// With a button for testing
$('#SomeButtonKillSignalr').click(function () {
            $.connection.hub.stop();                
        });

---

Updated with Option 3 : based on request... the other solutions rely on time out, but you can also force it directly by disposing the connection yourself

I opened the SignalR code up, and inside you can see DisposeAndRemoveAsync the actual termination of a client connection.

1- You can modify or call DisposeAndRemoveAsync with your connection.

2- Then call RemoveConnection(connection.ConnectionId);

public async Task DisposeAndRemoveAsync(HttpConnectionContext connection)
        {
            try
            {
                // this will force it
                await connection.DisposeAsync();
            }
            catch (IOException ex)
            {
                _logger.ConnectionReset(connection.ConnectionId, ex);
            }
            catch (WebSocketException ex) when (ex.InnerException is IOException)
            {
                _logger.ConnectionReset(connection.ConnectionId, ex);
            }
            catch (Exception ex)
            {
                _logger.FailedDispose(connection.ConnectionId, ex);
            }
            finally
            {
                // Remove it from the list after disposal so that's it's easy to see
                // connections that might be in a hung state via the connections list
                RemoveConnection(connection.ConnectionId);
            }
        }

Caution, do any clean up yourself when this is done.