阅读可观察的 TAP 模式

经过对 StackOverflow 的大量努力和研究——其中大部分已经过时，因为反应式扩展代码最近发生了变化——我终于能够消除这个从套接字读取数据的 Observable 方法的所有编译错误，我比一开始更好地理解了这段代码。 但不完全是。 有人可以用英语读给我听，并回答两三个问题吗？

缓冲数据是否从此方法中提取（或者如果我弄错了，应该如何）？ 是否有不再需要的部分？尽管我真的很喜欢与业务代码的解耦，并将所有套接字代码保存在一两种方法中，但有没有更好的方法可以做到这一点（解耦和可读）？

    public static IObservable<int> WhenDataReceived(this Socket socket, int byteCount, SocketFlags flags = SocketFlags.None)
    {
        Contract.Requires(byteCount > 0);
        return Observable.Create<int>(
            observer =>
            {
                byte[] buffer = new byte[byteCount];
                int remainder = byteCount;
                bool shutdown = false;
                return Observable.Defer<int>(() =>
                        Task.Factory.FromAsync<int>(socket.BeginReceive(buffer, buffer.Length - remainder, remainder, flags,
                        (result) =>
                        {
                            var read = (int)result.AsyncState;
                            remainder -= read;
                            if (read == 0)
                                shutdown = true;
                        },
                        null), socket.EndReceive).ToObservable())
                    .TakeWhile(_ => remainder > 0 && !shutdown)
                    .TakeLast(1)
                    .Subscribe(
                        observer.OnNext,
                        ex =>
                        {
                            var socketError = ex as SocketException;
                            if (socketError != null
                                && (socketError.SocketErrorCode == SocketError.Disconnecting
                                    || socketError.SocketErrorCode == SocketError.Shutdown))
                            {
                                observer.OnCompleted();
                            }
                            else { observer.OnError(ex); }
                        },
                        observer.OnCompleted);
            });
    }
}

调用它的函数仍然有我不明白的编译错误（.做和.位转换器有一些无效的参数）：

        static IObservable<string> StartClient(this IObserver<ScanInformation> observer, IPAddress ip, int port)
    {
        var client = Observable.Using(
            () => new Socket(AddressFamily.InterNetwork, SocketType.Stream, ProtocolType.Tcp),
            socket =>
            from _ in socket.WhenConnected(ip, port)
            from message in
                (from first in socket.WhenDataReceived(4)
                 let length = BitConverter.ToInt32(first, 0)
                 from message in
                     Observable.If(
                         condition: () => length > 0,
                         thenSource: from second in socket.WhenDataReceived(length)
                                     select Encoding.UTF8.GetString(second, 0, length),
                         elseSource: Observable.Return<string>(null))
                 select message)
                .Repeat()
                .TakeWhile(message => message != null)
            select message);
        return
            client.Do(observer).TakeLast(1);
    }