Node.java

   1 /*
   2  * @(#)Node.java
   3  * Time-stamp: "2007-10-16 13:20:44 spoof"
   4  */
   5
   6 import java.io.IOException;
   7 import java.util.Random;
   8 import java.net.InetAddress;
   9 import java.net.DatagramPacket;
  10
  11 /**
  12  * Node &ndash; a node in a packet ring
  13  *
  14  * @author "Anton Johansson" <anton.johansson@gmail.com>
  15  * @author "Victor Zamanian" <victor.zamanian@gmail.com>
  16  */
  17 public class Node implements NodeInterface {
  18
  19     // general Node information
  20     protected final int localPort;
  21     protected const InetAddress nextHost;
  22     protected final int nextPort;
  23     protected final int ID;
  24     protected final long startTime;
  25
  26     // keeps track of whether this Node
  27     // is a master node (sends the first message)
  28     // and/or a logger (logs lap times to a file)
  29     protected final boolean isMasterNode;
  30     protected final boolean isLogger;
  31
  32     // different message types
  33     protected final int FINDMASTER = 1;
  34     protected final int INITRING   = 2;
  35     protected final int TERMINATE  = 3;
  36     // message datagram size
  37     protected final int DATAGRAMSIZE = 100;
  38     // ID range (from 0 to...)
  39     private final int IDRANGE = 8192;
  40
  41     // number of packets to send in the ring
  42     protected final int PACKETSTOSEND = 500;
  43     // needed to calculate lap times
  44     protected int sentPackets = 0;
  45
  46     /**
  47      * Constructs a new object instance of the Node class.
  48      */
  49     public Node(int localPort,
  50                 InetAddress nextHost,
  51                 int nextPort,
  52                 boolean logger) {
  53
  54         // set some fields
  55         this.ID = 1024 + (new Random().nextInt(IDRANGE));
  56         this.localPort = localPort;
  57         this.nextHost = nextHost;
  58         this.nextPort = nextPort;
  59         this.isLogger = logger;
  60
  61         // print some information about this node
  62         System.out.println("Node listens on port no.: " + localPort +
  63                            "\nNext host in ring is: " + nextHost +
  64                            "\nNext host listens on port no.: " + nextPort);
  65         // if this node is assigned the task of
  66         // logging lap times to a log file
  67         if (isLogger) {
  68             System.out.println("This node (with ID: " + ID +
  69                                ") will log this session.");
  70         }
  71     }
  72
  73     /**
  74      * Returns the amount of packets that this Node has sent.
  75      *
  76      * @return int The number of packets send by this Node.
  77      */
  78     public int getSentPackets() {
  79         return this.sentPackets;
  80     }
  81
  82     /**
  83      * Returns the time when this Node started sending packets.
  84      *
  85      * @return long The number of milli-/nanoseconds that
  86      * have passed since this Node entered Phase Two.
  87      */
  88     public long getStartTime() {
  89         return this.startTime;
  90     }
  91
  92     /**
  93      * Sends a DatagramPacket through this Node's socket.
  94      * NOTE: Since the Node class is really just a container
  95      * for methods and fields for the subclasses of the Node class,
  96      * this methods does nothing but return 'false' because the
  97      * method of sending packets differ between UDPNode and TCPNode.
  98      *
  99      * @return boolean Whether or not the sending was successful.
 100      */
 101     public boolean sendPacket(DatagramPacket sendPacket){
 102         return false;
 103     }
 104
 105     /**
 106      * Receives a DatagramPacket from this Node's socket.
 107      * NOTE: This method does nothing but return 'false',
 108      * because: see note at sendPacket(DatagramPacket sendPacket).
 109      *
 110      * @return boolean Whether or not the receiving was successful.
 111      */
 112     public boolean receivePacket(DatagramPacket receivePacket) {
 113         return false;
 114     }
 115
 116     /**
 117      *
 118      *
 119      * @return DatagramPacket The packet constructed by this method.
 120      */
 121     public DatagramPacket constructPacket(int messageType, String message) {
 122
 123         if (message == null) {
 124             message = "";
 125         }
 126
 127         byte[] sendBytes = new byte[100];
 128         sendBytes[0] = (byte) messageType;
 129         sendBytes[1] = message.length() < 98 ? (byte) message.length() : (byte) 98;
 130
 131         for (int i=0; i<sendBytes[1]; i++) {
 132             sendBytes[2 + i] = (byte) message.charAt(i);
 133         }
 134         return new DatagramPacket(sendBytes,
 135                                   sendBytes.length,
 136                                   nextHost,
 137                                   nextPort);
 138     }
 139 }