==== 1.) Traditional socket based TCP server/client example ====


1/a) Socket server source

  import java.io.*;
  import java.net.*;
    
  public class Provider{
        ServerSocket providerSocket;
        Socket connection = null;
        ObjectOutputStream out;
        ObjectInputStream in;
        String message; 	
        Provider() {}
        void run() {
		try{
			providerSocket = new ServerSocket(8080, 10);
			connection = providerSocket.accept();
			out = new ObjectOutputStream(connection.getOutputStream());
			in = new ObjectInputStream(connection.getInputStream());
			
                        do {
				try {
					message = (String)in.readObject();
					System.out.println("client>" + message);
					if (message.equals("bye")) sendMessage("bye");
				}
				catch(ClassNotFoundException classnot){
					System.err.println("Data received in unknown format");
				}
			} while(!message.equals("bye"));
		}
		catch(IOException ioException){
			ioException.printStackTrace();
		}
		finally{
			try {
				in.close();
				out.close();
				providerSocket.close();
			}
			catch(IOException ioException){
				ioException.printStackTrace();
			}
		}
	}
        
	void sendMessage(String msg) {
		try {
			out.writeObject(msg);
			out.flush();
			System.out.println("server>" + msg);
		}
		catch(IOException ioException){
			ioException.printStackTrace();
		}
	}
        
	public static void main(String args[]) {
		Provider server = new Provider();
		while(true){
			server.run();
		}
	}
	}

1/b.) Client source


  import java.io.*;
  import java.net.*;
   
  public class Requester{
        Socket requestSocket;
        ObjectOutputStream out;
        ObjectInputStream in;
        String message;
        Requester(){}
	void run() {
		try{
			requestSocket = new Socket("localhost", 8080);
			out = new ObjectOutputStream(requestSocket.getOutputStream());
			in = new ObjectInputStream(requestSocket.getInputStream());
			do {
				try {
					sendMessage("Hello szerver");
					sendMessage("bye");
                                        message = (String)in.readObject();
				}
				catch(Exception e){
					System.err.println("data received in unknown format");
				}    
			} while(!message.equals("bye"));
		}
		catch(UnknownHostException unknownHost){
			System.err.println("You are trying to connect to an unknown host!");
		}
		catch(IOException ioException){
			ioException.printStackTrace();
		}
		finally{
			try{
				in.close();
				out.close();
				requestSocket.close();
			}
			catch(IOException ioException){
				ioException.printStackTrace();
			}
		}
	}
    
	void sendMessage(String msg) {
		try {
			out.writeObject(msg);
			out.flush();
			System.out.println("client>" + msg);
		}
		catch(IOException ioException){
			ioException.printStackTrace();
		}
	}
   
	public static void main(String args[]) {
		Requester client = new Requester();
		client.run();
	}
  }