Keep my TCP connection alive

[eggmanpete]

Hi again,

I'm having trouble keeping my TCP connection between my server and client alive.

Please take a look at my code and tell me what I am doing wrong:


TCP CLIENT

package networkTCP;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInputStream;
import java.io.PrintWriter;
import java.io.Serializable;
import java.net.*;
import java.util.ArrayList;

public class tcpclient implements Serializable
{
	public Socket echoSocket = null;
	public ArrayList board = new ArrayList();

	public void setupConnection() throws Exception
	{
		// keep connection alive here
		echoSocket = new Socket("127.0.0.1", 2323);
	}
	public ArrayList tcpsend(String coords) throws Exception
	{

		//Socket echoSocket = null;
		PrintWriter out = null;
		BufferedReader in = null;
		//start socket, and send console text input
		System.out.println("pressed");
		try
		{
			//temp
			//echoSocket = new Socket("127.0.0.1", 2323);
			out = new PrintWriter(echoSocket.getOutputStream(), true);
			//send coords to server
			out.println(coords);
			System.out.println("sent coords: " + coords);
			//InputStreamReader strmRead = new
			//InputStreamReader(echoSocket.getInputStream());
			//in = new BufferedReader(strmRead);

			// wait for reply from server
			System.out.println("Still alive?");
			//Socket serialsocket = new Socket("127.0.0.1", 2323);
			System.out.println("Still alive?");
			InputStream instr = echoSocket.getInputStream();
			System.out.println("waiting for board object to be returned!");
			ObjectInputStream ois = new ObjectInputStream(instr);
			System.out.println("board object returned");
			board = (ArrayList) ois.readObject();
			ois.close();
			//out.close();
			//in.close();
			//serialsocket.close();
			//echoSocket.close();
			//Thread.sleep(1000);

			/*
			int x = 0;
			while (x != board.size()) {
				System.out.println(board.get(x));
				x++;
			}
			x=0;

			 */

		} catch (UnknownHostException e) {
		    System.err.println("Don't know about host: 127.0.0.1.");
		    System.exit(1);
		} catch (IOException e) {
		    System.err.println("Couldn't get I/O for "
				       + "the connection to: 127.0.0.1.");
		    System.exit(1);
		}
		return board;
	}
	public static void main (String args[]) throws Exception
	{
		tcpclient client = new tcpclient();
		client.setupConnection();

		client.tcpsend("0,1");
		client.tcpsend("1,0");
	}
}

TCP SERVER

package networkTCP;
import java.net.*;
import java.io.*;
import java.io.Serializable;

public class tcpserver implements Serializable
{
	// create gameboard object
	public static gameboard.board board = new gameboard.board();

	public static void serverstart() throws IOException,
		InterruptedException
	{
		//what is setTCPNoDelay(); ??
		System.out.println("Hi, I'm the TCP server!");
		ServerSocket serverSocket = null;
		boolean listening = true;
		try {
		    serverSocket = new ServerSocket(2323);
		} catch (IOException e) {
		    System.err.println("listen error on port: 2323.");
		    System.exit(1);
		}
		while (listening)
		{
			new tcpserverthread(serverSocket.accept()).run();
		}
		//serverSocket.close();
	}

	public static void main(String[] args) throws IOException,
		InterruptedException {
		serverstart();
	}
}

TCP SERVER-THREAD

package networkTCP;

import java.net.*;
import java.io.*;
import java.util.ArrayList;

public class tcpserverthread extends tcpserver
{
	//global socket
	private Socket clientSocket = null;

	public tcpserverthread(Socket socket)
	{
		//super("tcpserverthread");
		this.clientSocket = socket;
	}
	public void run()
	{
		try {

			PrintWriter out = new PrintWriter(clientSocket.getOutputStream
				(), true);
			BufferedReader in = new BufferedReader(
				new InputStreamReader(
				clientSocket.getInputStream()));
			String inputLine = new String();
			System.out.println(clientSocket.getPort());
			OutputStream oStream = clientSocket.
				getOutputStream();
			ObjectOutputStream ooStream = new
			ObjectOutputStream (oStream);

			inputLine = in.readLine();
			while(true)
			{
				System.out.println("in1" + inputLine);
				String[] splitInput = inputLine.split(",");
				String colStr = new String (splitInput[0]);
				String rowStr = new String (splitInput[1]);
				int row = new Integer (Integer.
					parseInt(rowStr));
				int col = new Integer (Integer.
					parseInt(colStr));
				ArrayList finishBoard = new ArrayList();
				finishBoard = board.updateBoard(col, row);
				System.out.println(finishBoard);
				ooStream.writeObject(finishBoard);
				out.println(ooStream);
				System.out.println("done sending");
				//ooStream.close();
				System.out.println("in2" + inputLine);
				//inputLine = null;
				inputLine = in.readLine();
			}
		}

		catch (IOException e)
		{
			e.printStackTrace();
		}
    }
}

These are the errors:
Server:

run:
Hi, I'm the TCP server!
58554
in10,1
(correct arraylist display was here)
done sending
in20,1
java.net.SocketException: Connection reset
        at java.net.SocketInputStream.read(SocketInputStream.java:168)
        at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:264)
        at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:306)
        at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:158)
        at java.io.InputStreamReader.read(InputStreamReader.java:167)
        at java.io.BufferedReader.fill(BufferedReader.java:136)
        at java.io.BufferedReader.readLine(BufferedReader.java:299)
        at java.io.BufferedReader.readLine(BufferedReader.java:362)
        at networkTCP.tcpserverthread.run(tcpserverthread.java:53)
        at networkTCP.tcpserver.serverstart(tcpserver.java:26)
        at networkTCP.tcpserver.main(tcpserver.java:33)
BUILD STOPPED (total time: 12 seconds)

TCP CLIENT:

run:
pressed
sent coords: 0,1
Still alive?
Still alive?
waiting for board object to be returned!
board object returned
pressed
Couldn't get I/O for the connection to: 127.0.0.1.
Java Result: 1
BUILD SUCCESSFUL (total time: 0 seconds)

any help is greatly appreciated.

[fishtoprecords]

Why are you using localhost (127.0.0.1) on both sides? This makes zero sense.

[eggmanpete]

I'm not anymore

public void setupConnection(String IPAddy2) throws Exception
	{
		InetAddress IPAddy = InetAddress.getByName(IPAddy2);
		// keep connection alive here
		echoSocket = new Socket(IPAddy, 2323);
}

I have to call

setupConnection("10.0.0.1");

every time i need to send something

[Steve11235]

Try debugging the code on one side, and then the other. See what looks funny.

I'm guessing the client closes the connection after the first pass, and the server gets an error message.

[toadaly]

This is a definite problem, though not necessarily the only one.

ois.close();

When you close the ObjectInputStream, it closes it's underlying resources as well, which includes your Socket's InputStream.

If you are planning to reuse the same underlying InputStream, you do not need to close any streams wrapped around it (such as ObjectInputStream). Just let them go out of scope.