Talker.java

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.InetSocketAddress;
import java.net.Socket;

/**
 * Talker thread that processes request accepted by listener and writes
 * response to socket.
 * @author Chuan Xia
 *
 */

public class Talker implements Runnable{

	Socket talkSocket;
	private Node local;

	public Talker(Socket _talkSocket, Node _local)
	{
		talkSocket = _talkSocket;
		local = _local;
	}

	public void run()
	{
		InputStream input = null;
		OutputStream output = null;
		try {
			input = talkSocket.getInputStream();
			String request = Helper.inputStreamToString(input);
			String response = processRequest(request);
			if (response != null) {
				output = talkSocket.getOutputStream();
				output.write(response.getBytes());
			}
			input.close();
		} catch (IOException e) {
			throw new RuntimeException(
					"Cannot talk.\nServer port: "+local.getAddress().getPort()+"; Talker port: "+talkSocket.getPort(), e);
		}
	}

	private String processRequest(String request)
	{
		InetSocketAddress result = null;
		String ret = null;
		if (request  == null) {
			return null;
		}
		if (request.startsWith("CLOSEST")) {
			long id = Long.parseLong(request.split("_")[1]);
			result = local.closest_preceding_finger(id);
			String ip = result.getAddress().toString();
			int port = result.getPort();
			ret = "MYCLOSEST_"+ip+":"+port;
		}
		else if (request.startsWith("YOURSUCC")) {
			result =local.getSuccessor();
			if (result != null) {
				String ip = result.getAddress().toString();
				int port = result.getPort();
				ret = "MYSUCC_"+ip+":"+port;
			}
			else {
				ret = "NOTHING";
			}
		}
		else if (request.startsWith("YOURPRE")) {
			result =local.getPredecessor();
			if (result != null) {
				String ip = result.getAddress().toString();
				int port = result.getPort();
				ret = "MYPRE_"+ip+":"+port;
			}
			else {
				ret = "NOTHING";
			}
		}
		else if (request.startsWith("FINDSUCC")) {
			long id = Long.parseLong(request.split("_")[1]);
			result = local.find_successor(id);
			String ip = result.getAddress().toString();
			int port = result.getPort();
			ret = "FOUNDSUCC_"+ip+":"+port;
		}
		else if (request.startsWith("IAMPRE")) {
			InetSocketAddress new_pre = Helper.createSocketAddress(request.split("_")[1]);
			local.notified(new_pre);
			ret = "NOTIFIED";
		}
		else if (request.startsWith("KEEP")) {
			ret = "ALIVE";
		}
		return ret;
	}
}