Microsoft.AspNet.SignalR.SqlServer.ObservableDbOperation.StartSqlDependencyListener C# (CSharp) Method

        protected virtual bool StartSqlDependencyListener()
        {
            lock (_stopLocker)
            {
                if (_disposing)
                {
                    return false;
                }
            }

            if (_notificationState == NotificationState.Disabled)
            {
                return false;
            }

            Trace.TraceVerbose("{0}Starting SQL notification listener", TracePrefix);
            try
            {
                if (SqlDependency.Start(ConnectionString))
                {
                    Trace.TraceVerbose("{0}SQL notification listener started", TracePrefix);
                }
                else
                {
                    Trace.TraceVerbose("{0}SQL notification listener was already running", TracePrefix);
                }
                return true;
            }
            catch (InvalidOperationException)
            {
                Trace.TraceInformation("{0}SQL Service Broker is disabled, disabling query notifications", TracePrefix);

                _notificationState = NotificationState.Disabled;
                return false;
            }
            catch (Exception ex)
            {
                Trace.TraceError("{0}Error starting SQL notification listener: {1}", TracePrefix, ex);

                return false;
            }
        }