//------------
// Introduction to Programming Using Java: An Object-Oriented Approach
//	Arnow/Weiss
//------------
// the TCPConnection class
// Chapter 14, NET Supplement, Page 709-711

import java.net.*;
import java.io.*;
class TCPConnection {
    public TCPConnection(String hostname, int portnumber)
                                         throws Exception {
        Socket  s = makeSocket(hostname,portnumber);
        br = new BufferedReader(
                new InputStreamReader(
                   s.getInputStream()));
        ps = new PrintStream(s.getOutputStream());
    }
    public String readLine() throws Exception {
        String  s;
        try {
           s = br.readLine();
        } catch (IOException ioe) {
           System.err.println("TCP input failure: network error");
           throw new Exception("Input Failure: Network I/O Error");
        }
        return s;
    }
    public void println(String s) {
        ps.println(s);
    }
    private Socket makeSocket(String hostname, 
                         int portnumber) throws Exception {
        Socket s=null;
        int    attempts = 0;
        while (s==null && attempts<maxAttempts) {
           try {
               s  = new Socket(hostname, portnumber);
           } catch (UnknownHostException uhe) {
               System.err.println("Cannot make TCP connection. Reason: Unknown Host: "+hostname);
               throw new TCPException("Connection Failure: Unknown Host");
           } catch (IOException ioe) {
               System.err.println("Connection failed "+
                 "due to Network I/O Error: retrying ...");
           }
           attempts++;
        }
        if  (s==null)
           throw new IOException("Connection Failure: Net I/O Errors");
        else
           return  s;
    }
    private final int      maxAttempts=5;
        private BufferedReader  br;
        private PrintStream     ps;
}