public enum ConnectionState    {        /// <summary>        /// The state of this connection is undefined. This is the starting state of new connections.        /// 未定义   初始状态        /// </summary>        Undefined,        /// <summary>        /// The connection is in the process of being established/initialised.        /// 建立中        /// </summary>        Establishing,        /// <summary>        /// The connection has been successfully established.        /// 创建完成        /// </summary>        Established,        /// <summary>        /// The connection has been shutdown.        /// 关闭        /// </summary>        Shutdown    }