//********* Non-blocking server ***************************************

import java.nio.ByteBuffer;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.net.InetSocketAddress;

public class NBS {  // NonBlockingServer
    public static void main(String[ ] args) throws Exception {
        // Store the message in a ByteBuffer for sending.
        String msg = "Hello, world!";
        ByteBuffer buff = ByteBuffer.wrap(msg.getBytes());
    
        // Open a non-blocking ServerSocketChannel.
        ServerSocketChannel ssc = ServerSocketChannel.open();
        ssc.socket().bind(new InetSocketAddress(port));
        ssc.configureBlocking(false);

        // Await clients.
        while (true) {
            SocketChannel sc = ssc.accept(); // doesn't block
            if (sc == null) 
                Thread.sleep(winks); // there's a better way
            else {
                buff.rewind();    // set position to 1st byte
                while (buff.hasRemaining())
                  sc.write(buff); // write the bytes
                sc.close();       // close the connection
            }
        }
    }
    private static final int port = 2233;
    private static final int winks = 2000; // 2 seconds
}