Subversion Repositories programming

/*******************************************************************************

 * File: P1Client.java

 * Author: Ira W. Snyder (devel@irasnyder.com)

 * Class: CS380 - Computer Networking

 *

 * Assignment: Project #1

 * Date Last Modified: 2006-01-18

 *

 * Purpose: Opens a connection to a server running on port 1337 on the

 *          local machine. Sends 10 1024 Byte payloads to the server,

 *          measuring the time it takes to recieve them back.

 *          It uses this data to calculate the RTT between the applications.

 *

 ******************************************************************************/

import java.io.*;

import java.net.*;

import java.util.Date;

public class P1Client

{

    /* Instance Variables */

    private static final String exitSeq = "QUIT";

    private static final String hostName = "localhost";

    private static final int portNumber = 1337;

    private static final int numPackets = 10;

    private static final int packetSize = 1024;

    private static Date startTime;

    private static Date stopTime;

    /**

     * Method: generatePacket

     * Purpose: This method will generate a String that is size bytes in

     * length. This is assumed to be size bytes when transferred across

     * the network.

     */

    private static byte[] generatePacket (int size)

    {

        byte packet[] = new byte[size];

        int i = 0;

        for (i=0; i<size; i++)

            packet[i] = 10;

        return packet;

    }

    /**

     * Method: printTimingInfo

     * Purpose: This method will take the start and stop time and print

     * out all of the required statistics: totalTime, RTT, throughput.

     */

    private static void printTimingInfo (Date startTime, Date stopTime)

    {

        long totalTime = (stopTime.getTime() - startTime.getTime());

        double rtt = (double)totalTime / (double)numPackets;

        System.out.printf ("Time for %d x %d B packets: %d ms\n",

                numPackets, packetSize, totalTime);

        System.out.printf ("RTT per packet: %.3f ms\n", rtt);

        double _100Mbps = 100000000.0; /* bps */

        double _1MB = 8388608.0; /* bit */

        double transferTime = (rtt / 1000.0) + 1.0 / _100Mbps * _1MB;

        double throughput = _1MB / transferTime;

        System.out.printf ("Throughput: %d bits / sec\n", (int)throughput);

    }

    /**

     * Method: main

     * Purpose: This method sets up a network socket, connects to the

     * P1Server instance, and sends and times the transfer times.

     */

    public static void main (String[] args) throws IOException

    {

        Socket sendSocket = null;

        PrintWriter out = null;

        BufferedReader in = null;

        /* Set up the sockets */

        try

        {

            sendSocket = new Socket (hostName, portNumber);

            out = new PrintWriter (sendSocket.getOutputStream(), true);

            in = new BufferedReader (new InputStreamReader(

                                         sendSocket.getInputStream()));

        }

        catch (UnknownHostException e)

        {

            System.err.printf ("Can't resolve hostname: %s\n", hostName);

            System.exit(1);

        }

        catch (IOException e)

        {

            System.err.printf ("Couldn't get I/O for the connection to: %s\n", hostName);

            System.exit(1);

        }

        byte packet[] = generatePacket (packetSize);

        String response;

        int i = 0;

        /* Start the timer */

        startTime = new Date();

        /* Send all of the packets, recieve all of the responses */

        for (i=0; i<numPackets; i++)

        {

            out.println (packet);

            response = in.readLine();

        }

        /* Stop the timer */

        stopTime = new Date();

        /* Send the exit sequence */

        out.println (exitSeq);

        /* Calculate and print all timing info */

        printTimingInfo(startTime, stopTime);

        /* Cleanup */

        out.close();

        in.close();

        sendSocket.close();

    }

}