C#异步服务器/客户端体系结构 [英] C# Async Server/Client Architecture

问题描述

堆栈上的第一个帖子溢出！

first post ever on stack overflow!

无论如何...我想在业余时间自学网络编程，但遇到了麻烦，我实在无法解决问题.在玩了几天的同步网络方法之后，我决定制作一个客户端/服务器程序，该程序可以:

Anyway...I'm trying to teach myself networking programming in my spare time and I've reached a snag I just cant wrap my head around. After playing with synchronous networking methodology over a few days I decided to make a client/server program that could:

• 处理多个并发连接
• 处理多个通信流
• 实现真正的双向沟通​​

更一般地说，我想制作一个聊天程序.到服务器的多个客户端连接可以分别发送和接收数据而不会出现问题...但是还可以使服务器将数据从每个客户端发送到另一个客户端.

On a more general level I want to make a chat program. Multiple client connections to a server that can send and receive data individually with no problems...but also have the server send data from each client to the others.

现在我还没有达到我想要的程度，所以我在这里提供一些指导.我似乎无法使我的循环正常工作，并且我确定它与代码的异步性质有关……出于任何原因，我似乎都无法找出问题所在.这是代码块:

Now I haven't gotten as far as I'd like to yet so I'm here for a little guidance. I can't seem to get my loops working properly and I'm sure it has to do with the asynchronous nature of the code...for whatever reason I just can't seem to figure out whats wrong. Here's the the blocks of code:

Server.cs

Server.cs

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];
    IPAddress ipAddress = System.Net.IPAddress.Loopback;
    IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 3000);

    // 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;
}
}

Client.cs

Client.cs

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

public class StateObject
{
    // Client socket.
    public Socket workSocket = null;
    // Size of receive buffer.
    public const int BufferSize = 256;
    // Receive buffer.
    public byte[] buffer = new byte[BufferSize];
    // Received data string.
    public StringBuilder sb = new StringBuilder();
}

public class Program
{
    public static ManualResetEvent connectDone = new ManualResetEvent(false);
    public static ManualResetEvent sendDone = new ManualResetEvent(false);
    public static ManualResetEvent receiveDone = new ManualResetEvent(false);

    public static void Connect(EndPoint remoteEP, Socket client)
    {
        client.BeginConnect(remoteEP,
            new AsyncCallback(ConnectCallback), client);

        connectDone.WaitOne();
    }
    private static void ConnectCallback(IAsyncResult ar)
    {
        try
        {
            // Retrieve the socket from the state object.
            Socket client = (Socket)ar.AsyncState;

            // Complete the connection.
            client.EndConnect(ar);

            Console.WriteLine("Socket connected to {0}",
                client.RemoteEndPoint.ToString());

            // Signal that the connection has been made.
            connectDone.Set();
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
    }
    private static void Send(Socket client, 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.
        client.BeginSend(byteData, 0, byteData.Length, SocketFlags.None,
            new AsyncCallback(SendCallback), client);
    }
    private static void SendCallback(IAsyncResult ar)
    {
        try
        {
            // Retrieve the socket from the state object.
            Socket client = (Socket)ar.AsyncState;

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

            // Signal that all bytes have been sent.
            sendDone.Set();
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
    }
    private static void Receive(Socket client)
    {
        try
        {
            // Create the state object.
            StateObject state = new StateObject();
            state.workSocket = client;

            // Begin receiving the data from the remote device.
            client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                new AsyncCallback(ReceiveCallback), state);
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
    }
    private static void ReceiveCallback(IAsyncResult ar)
    {
        try
        {
            // Retrieve the state object and the client socket 
            // from the asynchronous state object.
            StateObject state = (StateObject)ar.AsyncState;
            Socket client = state.workSocket;
            // Read data from the remote device.
            int bytesRead = client.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));
                //  Get the rest of the data.
                client.BeginReceive(state.buffer, 0, StateObject.BufferSize, 0,
                    new AsyncCallback(ReceiveCallback), state);
            }
            else
            {
                // All the data has arrived; put it in response.
                if (state.sb.Length > 1)
                {
                    string response = state.sb.ToString();
                    Console.WriteLine(response);
                }
                // Signal that all bytes have been received.
                receiveDone.Set();
            }
        }
        catch (Exception e)
        {
            Console.WriteLine(e.ToString());
        }
    }
    static void Main(string[] args)
    {
        IPAddress ipAddress = System.Net.IPAddress.Loopback;
        IPEndPoint localEndPoint = new IPEndPoint(ipAddress, 3000);
        Socket sock = new Socket(AddressFamily.InterNetwork,SocketType.Stream,ProtocolType.Tcp);
        Connect(localEndPoint, sock);
        string packet;
        while (true)
        {
            packet = Console.ReadLine();
            packet += "<EOF>";
            Send(sock, packet);
            Receive(sock);
            connectDone.WaitOne();
        }
    }
}

推荐答案

异步时，您不需要任何循环或等待句柄.只需在AcceptCallback内部触发另一个beginAccept，服务器将在接受客户端后再次开始侦听.

You don't need any loops or waithandles when you go asynchronous. Just fire away another beginAccept inside AcceptCallback and you server will start listening again after accepting a client.

如果您的问题是服务器仅响应一次然后关闭，那么，这就是您所说的在SendCallback中要做的事情-它先发送内容，然后关闭.调用handler.beginReceive而不是handler.shutdown(您必须将StateObject一直携带到此回调中，而不仅仅是处理程序).

If your problem is that the server responses only once and then shuts down, then, well, that is what you say it to do in a SendCallback - it sends stuff and then shuts down. Call handler.beginReceive instead of handler.shutdown (you'll have to carry your StateObject all the way down to this callback, not just handler).

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