如何：使用命名管道通过网络在进程之间进行通信

姬风 2012-06-20

展开全文

命名管道提供的功能比匿名管道多。其功能包括通过网络进行全双工通信和多个服务器实例；基于消息的通信；以及客户端模拟，这使得连接进程可在远程服务器上使用其自己的权限集。

下面的示例演示如何使用 NamedPipeClientStream 类创建命名管道。在此示例中，服务器进程创建了四个线程。每个线程可以接受一个客户端连接。连接的客户端进程随后向服务器提供一个文件名。如果客户端具有足够的权限，服务器进程就会打开文件并将其内容发送回客户端。

using System;
using System.IO;
using System.IO.Pipes;
using System.Threading;

class PipeServer
{
    static int numThreads = 4;

    static void Main()
    {
        for (int i = 0; i < numThreads; i++)
        {
            Thread newThread = new Thread(new ThreadStart(ServerThread));
            newThread.Start();
        }
        Console.WriteLine("Press enter to exit.");
        Console.ReadLine();
    } // Main()

    private static void ServerThread()
    {
        using (NamedPipeServerStream pipeServer =
            new NamedPipeServerStream("testpipe", PipeDirection.InOut, numThreads))
        {
            Console.WriteLine("NamedPipeServerStream thread created.");

            // Wait for a client to connect
            pipeServer.WaitForConnection();

            Console.WriteLine("Client connected.");
            try
            {
                // Read the request from the client. Once the client has
                // written to the pipe its security token will be available.
                using (StreamReader sr = new StreamReader(pipeServer))
                using (StreamWriter sw = new StreamWriter(pipeServer))
                {
                    sw.AutoFlush = true;

                    // Verify our identity to the connected client using a
                    // string that the client anticipates.
                    sw.WriteLine("I am the true server!");

                    // Obtain the filename from the connected client.
                    string filename = sr.ReadLine();

                    // Read in the contents of the file while impersonating
                    // the client.
                    ReadFileToStream fileReader = new
                        ReadFileToStream(pipeServer, filename);

                    // Display the name of the user we are impersonating.
                    Console.WriteLine("Reading file: {0} as user {1}.",
                        pipeServer.GetImpersonationUserName(), filename);

                    pipeServer.RunAsClient(fileReader.Start);

                    pipeServer.Disconnect();
                }
           }
            // Catch the IOException that is raised if the pipe is broken
            // or disconnected.
            catch (IOException e)
            {
                Console.WriteLine("ERROR: {0}", e.Message);
            }
        }
    } // ServerThread()
} // PipeServer

class ReadFileToStream
{
    private string m_filename;
    private Stream m_stream;

    public ReadFileToStream(Stream stream, string filename)
    {
        m_filename = filename;
        m_stream = stream;
    } // ReadFileToStream(stream, filename)

    public void Start()
    {
        using (StreamWriter sw = new StreamWriter(m_stream))
        {
            string contents = File.ReadAllText(m_filename);
            sw.WriteLine(contents);
            sw.Flush();
        }
    } // Start()
} // ReadFileToStream

下面的示例演示使用 NamedPipeClientStream 类的客户端进程。客户端连接服务器进程并向服务器发送一个文件名。服务器随后将文件内容发送回客户端。文件内容随后显示在控制台上。

using System;
using System.IO;
using System.IO.Pipes;
using System.Security.Principal;

class PipeClient
{
    static int numThreads = 4;

    static void Main()
    {
        using (NamedPipeClientStream pipeClient = 
            new NamedPipeClientStream("localhost", "testpipe",
            PipeDirection.InOut, PipeOptions.None,
            TokenImpersonationLevel.Impersonation))
        using (StreamWriter sw = new StreamWriter(pipeClient))
        using (StreamReader sr = new StreamReader(pipeClient))
        {
            sw.AutoFlush = true;
            pipeClient.Connect();

            // Verify that this is the "true server"
            if (sr.ReadLine() == "I am the true server!")
            {
                // The client security token is sent with the first write.
                sw.WriteLine(@"c:\textfile.txt");

                // Print the file to the screen.
                char[] buffer = new char[32];
                int n;
                while ((n = sr.Read(buffer, 0, buffer.Length)) != 0)
                {
                    Console.Write(buffer, 0, n);
                }
            }
            else
            {
                Console.WriteLine("Server could not be verified.");
            }
        }
    } // Main()
}