Unable to understand InputStream.available() method, need some help

Question

dear friends,
The following is my doubt. please kindly help me in this. this will help me a lot in understanding some consepts.
Environment: i am using jdk1.4.1_01 on windowsxp.
i am using IE6.0 to make requets.
My requirement:
what i am actually trying to do is i want to see the raw material
send by the browser when we made a request to the server
by the browser.basically i want to see the request line
and headers as it is that is send by the browser to the server.
so i thought to code a server that can print the request send
by the browser as it is on the command window.
i had taken two examples and i am running Server2.java (look at the bottom for this code)and i made a 25 requests to the server2 program
which is running on port 8080 by the browser. here only once or twice in 25
times i was able to see the requests send by the browser.i tried hard and
found that InputStream.available() method is returning 0 even though the
request is sucessfully send to the port 8080 that is to the server2 program
which is listening to port 8080.
so in this process of experimenting i took Server3.java(i am sending this file
also as an attachment) which is using multithreading. in this also i did modification
as i did in Server2.java. the thing is here i am able to succed. here
InputStream.available method is returning the correct number of bytes
that are arrived on the port and are available to the InputStream.here
when ever i made a request from the browser to Server3.java i am able to
see the raw data send by the browser without failure.
i could not understand why InputStream.available() is returning 0
often(not all the time) and why it is giving the desired result when i
used it in Server3.java ?
i looked into the documentation and it says " InputStream.available() Returns the number of bytes that can be read (or skipped over) from this input stream without blocking
by the next caller of a method for this input stream."
so the thing i could not understand is what is blocking the InputStream
in the first case.if i could undrstand the internals of how this
method is working it will help me a lot.if i could understand this i
will know what is the right situations to use this method.
Thanking You.
/*Shows how to develop a simple network server
Author : Team -J
Version : 1.0 */
import java.net.*;
import java.io.*;
class Server2{
static public void main(String[] args)throws Exception{
     // create a new Server Socket
     try{
          ServerSocket ss = new ServerSocket(8080,1);     
     while(true){// set queue length to 1
          // wait for the connections
          Socket s = ss.accept();
          // get the output stream associated with socket
          // to write something to the socket
          PrintStream ps =new PrintStream( s.getOutputStream());
          InputStream is = s.getInputStream();
          ps.println("I am ready to provide xxx Service");
int len=is.available();
          if(len !=0)
          byte b [] = new byte[len];
          int k =is.read(b,0,(len-1));
          for(int i =0;i<k;i++)
               char c = (char)b;
               System.out.print(c);
          // close the connection
          is.close();
          s.close();
     }catch(Exception e){}
/*Shows how to develop a simple network server
Author : Team -J
Version : 1.0 */
import java.net.*;
import java.io.*;
class Server3{
static public void main(String[] args)throws Exception{
     // create a new Server Socket
     try{
          ServerSocket ss = new ServerSocket(8080,1);
          while(true){
               // wait for the connections
               Socket s = ss.accept();
               ServerThread st = new ServerThread(s);
               st.start();
     }catch(Exception e){}
class ServerThread extends Thread{
Socket s;
     public ServerThread(Socket s){
     this.s = s;
     public void run(){
          try{
          PrintStream ps =new PrintStream( s.getOutputStream());
          InputStream is = s.getInputStream();
          int len=is.available();
          ps.println("I am ready to provide xxx Service");
          if(len!=0)
          byte b [] = new byte[len];
          int k =is.read(b,0,(len-1));
          for(int i =0;i<k;i++)
               char c = (char)b[i];
               System.out.print(c);
          is.close();
          s.close();
          }catch(Exception e){}

Answer 1

so the thing i could not understand is what is
t is blocking the InputStream
in the first case.Blocking means the thread goes to sleep waiting for more data to arrive. InputStream.available() shows how many bytes have already arrived, not how many remain to be sent.