/// <summary>
        /// Opens the specified file for appending. Please call GetReply() after you have successfully transfered the file to read the "OK" command sent by the server and prevent stale data on the socket.
        /// </summary>
        /// <param name="path">The full or relative path to the file to be opened</param>
        /// <param name="type">ASCII/Binary</param>
        /// <returns>A stream for writing to the file on the server</returns>
        /// <example><code source="..\Examples\OpenAppend.cs" lang="cs" /></example>
        public virtual Stream OpenAppend(string path, FtpDataType type)
        {
            FtpTrace.WriteFunc("OpenAppend", new object[] { path, type });

            FtpClient     client = null;
            FtpDataStream stream = null;
            long          length = 0;

            lock (m_lock) {
                if (m_threadSafeDataChannels)
                {
                    client = CloneConnection();
                    client.Connect();
                    client.SetWorkingDirectory(GetWorkingDirectory());
                }
                else
                {
                    client = this;
                }

                client.SetDataType(type);
                length = client.GetFileSize(path);
                stream = client.OpenDataStream(("APPE " + path.GetFtpPath()), 0);

                if (length > 0 && stream != null)
                {
                    stream.SetLength(length);
                    stream.SetPosition(length);
                }
            }

            return(stream);
        }
        /// <summary>
        /// Opens the specified file for reading
        /// </summary>
        /// <param name="path">The full or relative path of the file</param>
        /// <param name="type">ASCII/Binary</param>
        /// <param name="restart">Resume location</param>
        /// <returns>A stream for reading the file on the server</returns>
        /// <example><code source="..\Examples\OpenRead.cs" lang="cs" /></example>
        public virtual Stream OpenRead(string path, FtpDataType type, long restart)
        {
            // verify args
            if (path.IsBlank())
            {
                throw new ArgumentException("Required parameter is null or blank.", "path");
            }

            FtpTrace.WriteFunc("OpenRead", new object[] { path, type, restart });

            FtpClient     client = null;
            FtpDataStream stream = null;
            long          length = 0;

#if !CORE14
            lock (m_lock) {
#endif
            if (m_threadSafeDataChannels)
            {
                client = CloneConnection();
                client.Connect();
                client.SetWorkingDirectory(GetWorkingDirectory());
            }
            else
            {
                client = this;
            }

            client.SetDataType(type);
            length = client.GetFileSize(path);
            stream = client.OpenDataStream(("RETR " + path.GetFtpPath()), restart);
#if !CORE14
        }
#endif

            if (stream != null)
            {
                if (length > 0)
                {
                    stream.SetLength(length);
                }

                if (restart > 0)
                {
                    stream.SetPosition(restart);
                }
            }

            return(stream);
        }