/// <summary>
        /// Called when a connection has disconnected gracefully from this hub instance,
        /// i.e. stop was called on the client.
        /// </summary>
        /// <returns>
        /// A <see cref="T:System.Threading.Tasks.Task" />
        /// </returns>

        public override Task OnDisconnected(bool stopCalled)
        {
            var name  = ((ServiceUser)Context.User).Id.Split(':')[1];
            var table = GetConnectionTable();

            try {
                if (!string.IsNullOrEmpty(name))
                {
                    var deleteOperation = TableOperation.Delete(
                        new SignalRUserStore(name, Context.ConnectionId)
                    {
                        ETag = "*"
                    });
                    TableOperation   retrieveOperation = TableOperation.Retrieve <SignalRUserStore>(name, Context.ConnectionId);
                    TableResult      retrievedResult   = table.Execute(retrieveOperation);
                    SignalRUserStore checkEntity       = retrievedResult.Result as SignalRUserStore;

                    if (checkEntity != null)
                    {
                        table.Execute(deleteOperation);
                    }
                }
            }

            catch (Exception ex) {
                //throw;
            }

            return(base.OnDisconnected(stopCalled));
        }
        /// <summary>
        /// Called when the connection connects to this hub instance.
        /// Code taken from:
        /// http://www.asp.net/signalr/overview/signalr-20/hubs-api/mapping-users-to-connections
        /// </summary>
        /// <returns>
        /// A <see cref="T:System.Threading.Tasks.Task" />
        /// </returns>

        public override Task OnConnected()
        {
            try {
                var currentUser = ((ServiceUser)Context.User).Id;
                var id          = Context.ConnectionId;

                var table = GetConnectionTable();
                table.CreateIfNotExists();

                var entity = new SignalRUserStore(
                    currentUser.Split(':')[1],
                    Context.ConnectionId);
                var insertOperation = TableOperation.InsertOrReplace(entity);
                table.Execute(insertOperation);
            }

            catch (Exception ex) {
                Debug.WriteLine(ex.ToString());
            }


            return(base.OnConnected());
        }