/// <summary>
        /// Sends keep-alive message to the server.
        /// </summary>
        /// <exception cref="ObjectDisposedException">The method was called after the client was disposed.</exception>
        public void SendKeepAlive()
        {
            CheckDisposed();

            if (Session != null && Session.IsConnected)
            {
                Session.SendKeepAlive();
            }
        }