C#的命名管道(named pipe)

命名管道是一種從一個進程到另一個進程用內核對象來進行信息傳輸。和一般的管道不同，命名管道可以被不同進程以不同的方式方法調用（可以跨權限、跨語言、跨平台）。只要程序知道命名管道的名字，發送到命名管道里的信息可以被一切擁有指定授權的程序讀取，但對不具有制定授權的。命名管道是一種FIFO（先進先出，First-In First-Out）對象。

我們可以使用命名管道在2個不同的進程中進行通信而不需要通過一般的IO讀寫文件來獲取信息。

在C#中可以簡單的這么用用來接收消息

using System.IO.Pipes;

private volatile NamedPipeServerStream _OutputNamedPipe;
_OutputNamedPipe = new NamedPipeServerStream(pipeName, PipeDirection.InOut, 254);
private void BeginReceiveOutput()
{               
    try
    {   
        _OutputNamedPipe.WaitForConnection();
        using (var reader = new StreamReader(_OutputNamedPipe))
        {
            _OutputMessage = reader.ReadLine();
         }                     
     }
     catch
     {              
     }            
}    

在vbscript里可以這樣來發消息

Dim fs, pipe
Set fs = CreateObject("Scripting.FileSystemObject")
Set pipe = fs.OpenTextFile("\\.\pipe\PipeName", 8, False, 0)
pipe.WriteLine("This is a message from vbs")
pipe.Close

更為嚴謹的寫法

    class Server
    {
        static void Main(string[] args)
        {
            var running = true;

            while (running) // loop only for 1 client
            {
                using (var server = new NamedPipeServerStream("PIPE_NAME", PipeDirection.InOut))
                {
                    server.WaitForConnection();

                    Console.WriteLine("Client connected");

                    using (var pipe = new PipeStream(server))
                    {
                        pipe.Send("handshake");

                        Console.WriteLine(pipe.Receive());

                        server.WaitForPipeDrain();
                        server.Flush();
                    }
                }
            }

            Console.WriteLine("server closed");
            Console.Read();
        }
    }

    class Client
    {
        static void Main(string[] args)
        {
            using (var client = new NamedPipeClientStream(".", "PIPE_NAME", PipeDirection.InOut))
            {
                client.Connect(2000);

                using (var pipe = new PipeStream(client))
                {
                    Console.WriteLine("Message: " + pipe.Receive());

                    pipe.Send("Hello!!!");
                }
            }

            Console.Read();
        }
    }

    public class PipeStream : IDisposable
    {
        private readonly Stream _stream;
        private readonly Reader _reader;
        private readonly Writer _writer;

        public PipeStream(Stream stream)
        {
            _stream = stream;

            _reader = new Reader(_stream);
            _writer = new Writer(_stream);
        }

        public string Receive()
        {
            return _reader.ReadLine();
        }

        public void Send(string message)
        {
            _writer.WriteLine(message);
            _writer.Flush();
        }

        public void Dispose()
        {
            _reader.Dispose();
            _writer.Dispose();

            _stream.Dispose();
        }

        private class Reader : StreamReader
        {
            public Reader(Stream stream)
                : base(stream)
            {

            }

            protected override void Dispose(bool disposing)
            {
                base.Dispose(false);
            }
        }

        private class Writer : StreamWriter
        {
            public Writer(Stream stream)
                : base(stream)
            {

            }

            protected override void Dispose(bool disposing)
            {
                base.Dispose(false);
            }
        }
    }