TCPServer.java

import java.io.*;
import java.net.*;

class TCPServer{

public static void main(String argv[]) throws Exception {

String clientSentence;
String capitalizedSentence;

ServerSocket welcomeSocket = new ServerSocket(6789);

System.out.println("Waiting for incoming connection Request...");

while(true) {
Socket connectionSocket = welcomeSocket.accept();

BufferedReader inFromClient =new BufferedReader
(new InputStreamReader(connectionSocket.getInputStream()));

DataOutputStream outToClient =new DataOutputStream(connectionSocket.getOutputStream());

while (true)
{
clientSentence = inFromClient.readLine();

System.out.println("RECEIVED FROM CLIENT: " + clientSentence);

capitalizedSentence = clientSentence.toUpperCase() + "\n"; 

outToClient.writeBytes(capitalizedSentence);
}
}
}
}