套接字编程：多个客户端一个服务器

Question

套接字编程：多个客户端一个服务器

c#multithreadingsockets

20

我刚开始学习在C#中进行套接字编程，并且遇到了一个问题。如何在单个服务器上处理多个客户端而无需为每个客户端创建线程？

当有10个客户端时，每个客户端创建一个线程的方法效果很好，但如果客户端数量增加到1000个，为每个客户端创建线程是否明智？如果有其他方法，请告诉我好吗？

- Prerak Pradhan

1

尝试访问http://www.codeproject.com/Articles/83102/C-SocketAsyncEventArgs-High-Performance-Socket-Cod...如果您搜索“async socket c#”，那里有数百万篇文章。 - atlaste

如果你在谷歌上搜索“C#套接字编程入门”，会有数百个例子。如果你更喜欢视频，也有很多关于这个主题的优秀YouTube视频。 - MarcF

使用 ipAddress = 0.0.0.0 可以在所有网络适配器上监听。 - Eduardo Castellanos Huicochea

3个回答

1

线程可以正常工作，但很少能够扩展到那么多客户端。有两种简单的方法和许多更复杂的方法来处理这个问题，以下是通常如何构建这两种更容易的方法的伪代码，以便让您了解。

select()

这是一个调用，用于检查哪些套接字有新的客户端或等待数据，一个典型的程序看起来像这样。

server = socket(), bind(), listen()
while(run)
   status = select(server)
   if has new client
       newclient = server.accept()
       handle add client
   if has new data
       read and handle data

这意味着不需要线程来处理多个客户端，但如果处理数据需要很长时间，它也不能很好地扩展，那么在完成之前，您将无法读取新数据或接受新的客户端。

异步套接字是另一种处理套接字的方式，它有点抽象化，高于select。您只需为常见事件设置回调，并让框架完成不太繁重的工作。

 function handleNewClient() { do stuff and then beginReceive(handleNewData) }
 function handleNewData() { do stuff and then beginReceive(handleNewData) }
 server = create, bind, listen etc
 server.beginAddNewClientHandler(handleNewClient)
 server.start()

我认为如果你的数据处理时间较长，这个程序应该会更好地扩展。那么你将进行哪种类型的数据处理？

- dutt

0

这可能是一个很好的起点。如果你想避免1个线程<->1个客户端的情况，那么你应该使用.NET提供的异步套接字工具。在这里要使用的核心对象是SocketAsyncEventArgs。

- Kaveh Shahbazian

网页内容由stack overflow 提供, 点击上面的

可以查看英文原文，
原文链接

- Dave Miles · Accepted Answer

尝试使用异步服务器。以下示例程序创建一个服务器，接收来自客户端的连接请求。该服务器使用异步套接字构建，因此在等待来自客户端的连接时，不会暂停服务器应用程序的执行。该应用程序从客户端接收字符串，在控制台上显示字符串，然后将字符串回显给客户端。来自客户端的字符串必须包含字符串<EOF>以表示消息的结束。

using System;
using System.Net;
using System.Net.Sockets;
using System.Text;
using System.Threading;

// State object for reading client data asynchronously
public class StateObject {
    // Client  socket.
    public Socket workSocket = null;
    // Size of receive buffer.
    public const int BufferSize = 1024;
    // Receive buffer.
    public byte[] buffer = new byte[BufferSize];
    // Received data string.
    public StringBuilder sb = new StringBuilder();  
}

public class AsynchronousSocketListener {
    // Thread signal.
    public static ManualResetEvent allDone = new ManualResetEvent(false);

    public AsynchronousSocketListener() {
    }

    public static void StartListening() {
        // Data buffer for incoming data.
        byte[] bytes = new Byte[1024];

        // Establish the local endpoint for the socket.
        // The DNS name of the computer
        // running the listener is "host.contoso.com".
        IPHostEntry ipHostInfo = Dns.Resolve(Dns.GetHostName());
        IPAddress ipAddress = ipHostInfo.AddressList[0];
        IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 11000);

        // Create a TCP/IP socket.
        Socket listener = new Socket(AddressFamily.InterNetwork,
            SocketType.Stream, ProtocolType.Tcp );

        // Bind the socket to the local endpoint and listen for incoming connections.
        try {
            listener.Bind(localEndPoint);
            listener.Listen(100);

            while (true) {
                // Set the event to nonsignaled state.
                allDone.Reset();

                // Start an asynchronous socket to listen for connections.
                Console.WriteLine("Waiting for a connection...");
                listener.BeginAccept( 
                    new AsyncCallback(AcceptCallback),
                    listener );

                // Wait until a connection is made before continuing.
                allDone.WaitOne();
            }

        } catch (Exception e) {
            Console.WriteLine(e.ToString());
        }

        Console.WriteLine("\nPress ENTER to continue...");
        Console.Read();

    }

    public static void AcceptCallback(IAsyncResult ar) {
        // Signal the main thread to continue.
        allDone.Set();

        // Get the socket that handles the client request.
        Socket listener = (Socket) ar.AsyncState;
        Socket handler = listener.EndAccept(ar);

        // Create the state object.
        StateObject state = new StateObject();
        state.workSocket = handler;
        handler.BeginReceive( state.buffer, 0, StateObject.BufferSize, 0,
            new AsyncCallback(ReadCallback), state);
    }

    public static void ReadCallback(IAsyncResult ar) {
        String content = String.Empty;

        // Retrieve the state object and the handler socket
        // from the asynchronous state object.
        StateObject state = (StateObject) ar.AsyncState;
        Socket handler = state.workSocket;

        // Read data from the client socket. 
        int bytesRead = handler.EndReceive(ar);

        if (bytesRead > 0) {
            // There  might be more data, so store the data received so far.
            state.sb.Append(Encoding.ASCII.GetString(
                state.buffer,0,bytesRead));

            // Check for end-of-file tag. If it is not there, read 
            // more data.
            content = state.sb.ToString();
            if (content.IndexOf("<EOF>") > -1) {
                // All the data has been read from the 
                // client. Display it on the console.
                Console.WriteLine("Read {0} bytes from socket. \n Data : {1}",
                    content.Length, content );
                // Echo the data back to the client.
                Send(handler, content);
            } else {
                // Not all data received. Get more.
                handler.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                new AsyncCallback(ReadCallback), state);
            }
        }
    }

    private static void Send(Socket handler, String data) {
        // Convert the string data to byte data using ASCII encoding.

        byte[] byteData = Encoding.ASCII.GetBytes(data);

        // Begin sending the data to the remote device.
        handler.BeginSend(byteData, 0, byteData.Length, 0,
            new AsyncCallback(SendCallback), handler);
    }

    private static void SendCallback(IAsyncResult ar) {
        try {
            // Retrieve the socket from the state object.
            Socket handler = (Socket) ar.AsyncState;

            // Complete sending the data to the remote device.
            int bytesSent = handler.EndSend(ar);
            Console.WriteLine("Sent {0} bytes to client.", bytesSent);

            handler.Shutdown(SocketShutdown.Both);
            handler.Close();

        } catch (Exception e) {
            Console.WriteLine(e.ToString());
        }
    }   

    public static int Main(String[] args) {
        StartListening();
        return 0;
    }
}

那将是最好的解决方案。