How to implement a persistent HTTP connection on client side...

Question

Sorry for the inconvenience everyone, but I could really use some help here since I am a total newbie to Java programming
I am trying to implement a persistent HTTP connection on the client side with request pipelining. The way I understand it is that client requests will be sent to the server, which will reply to them back to back, and then the client will read them accordingly. But when I read the server responses, I get only the reply for the first request, and nothing further, when I actually expect it to give me as many responses as the number of requests I ussued. Here is a sample code illustrating what I am trying to do.
====================
import java.io.*;
import java.net.*;
import java.util.*;
public class HttpClient {
public static String host = "www.somehost.com";
public static int port = 80;
public static String pathname = "/download.asp";
public static String protocol = "http";
public static ArrayList list;
public static void main(String[] args) {
Parser parser = new Parser();
list = parser.getIDs();
try {
Socket socket = new Socket(host, port);
InputStream from_server = socket.getInputStream();
PrintWriter to_server = new PrintWriter(socket.getOutputStream());
OutputStream to_file;
to_file = new FileOutputStream("HTTP_response.txt", true);
for(int i = 0; i < 3; i++)
String s = (String)parser.getIDs().get(i);
String filename = "/download.asp?id=" + s;
to_server.print("GET " + filename + "\n\n");
to_server.flush(); // Send it right now!
//This response gives only  only the response to the first
//request,....
byte[] buffer = new byte[4096];
int bytes_read;
while((bytes_read = from_server.read(buffer)) != -1)
to_file.write(buffer, 0, bytes_read);
to_file.close();
socket.close();
catch (Exception e) {
System.err.println(e);
System.err.println("Usage: java HttpClient <URL> [<filename>]");
}

Answer 1

There are many things wrong with your code. Learn the HTTP protocol and you'll know what I mean.
Here's a hint - you'r missing headers in your code.
Some servers do not support keep-alive connections, nor do you request a keep-alive connection.
Connection: keep-alive
Use that header field and see what happends. Also, in your while-loop, you actually close the output file and the socket. Don't you think it may be hard for the server to respond to a client that closed the connection on it?
1. You don't know HTTP
2. You don't seem to know Java
3. You don't seem to understand basic programming logic