■求助■如何用，c#实现聊天室？■■■

目前写了一套聊天室程序，使用tcp协议，server和client都启动了监听，实现双向传输文件和消息。但是朋友说这样不行，client不可以开监听，说这样对机器的负担太重。目前不知道怎么办了，具体的要求就是，双向传输，server处于监听状态，client在连接server后，server可以给client发消息（数据流）。

多谢
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try UDP

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

namespace UdpServer
{
///

1<summary>   
2/// Summary description for Class1.   
3/// </summary>

class Char
{
private static IPAddress remoteIPAddress;
private static int remotePort;
private static int localPort;
///

1<summary>   
2/// The main entry point for the application.   
3/// </summary>

[STAThread]
static void Main(string[] args)
{
try
{
//Get necessary data for connection
Console.WriteLine("Enter Local port");
localPort = Convert.ToInt16(Console.ReadLine());

Console.WriteLine("Enter remote port");
remotePort = Convert.ToInt16(Console.ReadLine());

Console.WriteLine("Enter remote IP Address");
remoteIPAddress = IPAddress.Parse(Console.ReadLine());

//Create thread for listening
Thread tRec = new Thread(new ThreadStart(Receiver));
tRec.Start();

while(true)
{
Send(Console.ReadLine());
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}

private static void Send(string datagram)
{
//Create UdpClient
UdpClient sender = new UdpClient();

//Create IPEndPoint with detail of remote host
IPEndPoint endPoint = new IPEndPoint(remoteIPAddress,remotePort);

try
{
byte[] bytes = Encoding.ASCII.GetBytes(datagram);
sender.Send(bytes,bytes.Length,endPoint);
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
finally
{
sender.Close();
}
}

private static void Receiver()
{
//Create a UdpClient for reading incoming data.
UdpClient receivingUdpClient = new UdpClient(localPort);

//IPEndPoint with remote host information
IPEndPoint RemoteIPEndPoint = null;

try
{
Console.WriteLine("---------------**Ready for char!!!!------------");
while(true)
{
//wait for datagram
byte[] receiveBytes = receivingUdpClient.Receive(ref RemoteIPEndPoint);

//Convert and display data
string returndata = Encoding.ASCII.GetString(receiveBytes);
Console.WriteLine("-"+returndata.ToString());
}
}
catch (Exception ex)
{
Console.WriteLine(ex.ToString());
}
}
}
}

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连接好后，也用客户端向服务器端发消息就是了
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编写一个web项目。采用XML。建立无刷新页面