ALTER DATABASE MyDatabase SET ENABLE_BROKER WITH ROLLBACK IMMEDIATE

        public frmMain()
        {
                ...
                test();
        }

        private void test()
        {
            AddSQL2Monitor("select [pk_id] from [dbo].[tbDispLeg]");
        }

        public void AddSQL2Monitor(String sqlRequest)
        {
            if (!CanRequestNotifications())
                throw new Exception("App has no SqlClientPermission -> Can't use SQL Dependency");
            AddDataMonitor(sqlRequest);
        }

        private bool CanRequestNotifications()
        {
            // In order to use the callback feature of the
            // SqlDependency, the application must have
            // the SqlClientPermission permission.
            try
            {
                SqlClientPermission perm =
                    new SqlClientPermission(
                    System.Security.Permissions.PermissionState.Unrestricted);

                perm.Demand();

                return true;
            }
            catch
            {
                return false;
            }
        }

        private void AddDataMonitor(String sqlRequest)
        {
            if (connection == null)
            {
                connection = new SqlConnection(GetConnectionString());
            }
            if (connection.State != ConnectionState.Open) connection.Open();
            command = new SqlCommand(sqlRequest, connection);

            SqlDependency.Start(command.Connection.ConnectionString);
            command.Notification = null;
            new SqlDependency(command).OnChange += new OnChangeEventHandler(dependency_OnChange);
            DataTable table = new DataTable();
            using (SqlDataAdapter sqlDA = new SqlDataAdapter(command))
                sqlDA.Fill(table);
        }
    

        private void dependency_OnChange(object sender, SqlNotificationEventArgs e)
        {
            command.Notification = null;
            new SqlDependency(command).OnChange += new OnChangeEventHandler(dependency_OnChange);
            DataTable table = new DataTable();
            using (SqlDataAdapter sqlDA = new SqlDataAdapter(command))
                sqlDA.Fill(table);
        }