Client.java

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.Socket;

public class Client {
    public static void main(String[] argv)
    {
        PrintWriter out;
        BufferedReader in;
        try
        {
            Socket sock = new Socket("localhost", 1843);
            sock.setSoTimeout(20000);
            out = new PrintWriter(sock.getOutputStream(), true);
            in =new BufferedReader(new InputStreamReader(sock.getInputStream()));
            out.print("<policy-file-request/>\0");
            out.flush();
            String r;

            while((r = in.readLine()) != null)
            {
                System.out.println(r);
            }

            out.close();
            in.close();
            sock.close();
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
    }
}

Server.java

import org.jboss.netty.bootstrap.ServerBootstrap;
import org.jboss.netty.channel.*;
import org.jboss.netty.channel.socket.SocketChannelConfig;
import org.jboss.netty.channel.socket.nio.NioServerSocketChannelFactory;
import org.jboss.netty.handler.codec.frame.DelimiterBasedFrameDecoder;
import org.jboss.netty.handler.codec.frame.Delimiters;
import org.jboss.netty.handler.codec.string.StringDecoder;
import org.jboss.netty.handler.codec.string.StringEncoder;
import org.jboss.netty.handler.timeout.ReadTimeoutHandler;
import org.jboss.netty.util.CharsetUtil;
import org.jboss.netty.util.HashedWheelTimer;
import org.jboss.netty.util.Timer;

import java.net.InetSocketAddress;
import java.util.concurrent.*;

import static org.jboss.netty.channel.Channels.pipeline;

public class Server {
    static final Timer timer = new HashedWheelTimer(100, TimeUnit.MILLISECONDS, 256);
    public static final String POLICY_REQUEST = "<policy-file-request/>";
    public static final String POLICY_XML =
        "<?xml version=\"1.0\"?>" +
                "<!DOCTYPE cross-domain-policy SYSTEM \"/xml/dtds/cross-domain-policy.dtd\">\n" +
                "<cross-domain-policy>\n" +
                "   <site-control permitted-cross-domain-policies=\"master-only\"/>\n" +
                "   <allow-access-from domain=\"*\" to-ports=\"80,2000-2100,20010\" />\n" +
                "</cross-domain-policy>";

    public static final ExecutorService ex = new ThreadPoolExecutor(100, 2000, 10, TimeUnit.SECONDS,
            new SynchronousQueue<Runnable>(true));

    public static void main(String[] argv) throws Exception
    {
        ServerBootstrap bootstrap = new ServerBootstrap(new NioServerSocketChannelFactory(
                Executors.newCachedThreadPool(),
                Executors.newCachedThreadPool()));

        bootstrap.setPipelineFactory(new ChannelPipelineFactory() {
            public ChannelPipeline getPipeline() throws Exception
            {
                ChannelPipeline pipeline = pipeline();

                pipeline.addLast("timer", new ReadTimeoutHandler(timer, 10));
                pipeline.addLast("frameDecoder", new DelimiterBasedFrameDecoder(1024, Delimiters.nulDelimiter()));
                pipeline.addLast("stringDecoder", new StringDecoder(CharsetUtil.UTF_8));
                pipeline.addLast("main", new SimpleChannelHandler() {
                    @Override
                    public void channelConnected(ChannelHandlerContext ctx, final ChannelStateEvent e) throws Exception
                    {
                        SocketChannelConfig cc = (SocketChannelConfig) e.getChannel().getConfig();
                        cc.setTcpNoDelay(true);
                    }

                    @Override
                    public void messageReceived(ChannelHandlerContext ctx, final MessageEvent e) throws Exception
                    {
                        String msg = (String) e.getMessage();

                        if (msg.equalsIgnoreCase(POLICY_REQUEST))
                        {
                            ex.execute(new Runnable() {
                                public void run()
                                {
                                    e.getChannel().write(POLICY_XML + "\0");
                                }
                            });
                        }
                        else
                        {
                            e.getChannel().close();
                        }
                    }

                    @Override
                    public void exceptionCaught(ChannelHandlerContext ctx, ExceptionEvent e) throws Exception
                    {
                        e.getChannel().close();
                    }

                });
                pipeline.addLast("stringEncoder", new StringEncoder(CharsetUtil.UTF_8));

                return pipeline;
            }
        });
        bootstrap.setOption("reuseAddress", true);
        bootstrap.setOption("child.reuseAddress", true);

        bootstrap.bind(new InetSocketAddress(1843));
    }
}