Use the Average Waiting Time program to determine a reasonable number of queues to use if there are 1000 customers and:

a) The inner-arrival time is 5 and the service time is 5

b) The inner-arrival time is 1 and the service time is 5

c) The inner-arrival time ranges from 0 to 20, and the service time ranges from 20 to 100

d) The inner-arrival time ranges from 0 to 2, and the service time ranges from 20 to 100

In each case, descripe how you arrived at your result

//---------------------------------------------------------------------

// Simulation.java by Dale/Joyce/Weems Chapter 5

//

// Models a sequence of customers being serviced

// by a number of queues.

//---------------------------------------------------------------------

import support.*; // Customer, CustomerGenerator

import ch05.queues.*;

public class Simulation

{

final int MAXTIME = Integer.MAX_VALUE;

CustomerGenerator custGen; // a customer generator

float avgWaitTime = 0.0f; // average wait time for most recent simulation

public Simulation(int minIAT, int maxIAT, int minST, int maxST)

{

custGen = new CustomerGenerator(minIAT, maxIAT, minST, maxST);

}

public float getAvgWaitTime()

{

return avgWaitTime;

}

public void simulate(int numQueues, int numCustomers)

// Preconditions: numQueues > 0

// numCustomers > 0

// No time generated during simulation is > MAXTIME

//

// Simulates numCustomers customers entering and leaving the

// a queuing system with numQueues queues

{

// the queues

GlassQueue[] queues = new GlassQueue[numQueues];

Customer nextCust; // next customer from generator

Customer cust; // holds customer for temporary use

int totWaitTime = 0; // total wait time

int custInCount = 0; // count of customers started so far

int custOutCount = 0; // count of customers finished so far

int nextArrTime; // next arrival time

int nextDepTime; // next departure time

int nextQueue; // index of queue for next departure

int shortest; // index of shortest queue

int shortestSize; // size of shortest queue

Customer rearCust; // customer at rear of shortest queue

int finishTime; // calculated finish time for customer being enqueued

// instantiate the queues

for (int i = 0; i < numQueues; i++)

queues[i] = new GlassQueue();

// set customer generator and get first customer

custGen.reset();

nextCust = custGen.nextCustomer();

while (custOutCount < numCustomers) // while still more customers to handle

{

// get next arrival time

if (custInCount != numCustomers)

nextArrTime = nextCust.getArrivalTime();

else

nextArrTime = MAXTIME;

// get next departure time and set nextQueue

nextDepTime = MAXTIME;

nextQueue = -1;

for (int i = 0; i < numQueues; i++)

if (queues[i].size() != 0)

{

cust = queues[i].peekFront();

if (cust.getFinishTime() < nextDepTime)

{

nextDepTime = cust.getFinishTime();

nextQueue = i;

}

}

if (nextArrTime < nextDepTime)

// handle customer arriving

{

// determine shortest queue

shortest = 0;

shortestSize = queues[0].size();

for (int i = 1; i < numQueues; i++)

{

if (queues[i].size() < shortestSize)

{

shortest = i;

shortestSize = queues[i].size();

}

}

// determine the finish time

if (shortestSize == 0)

finishTime = nextCust.getArrivalTime() + nextCust.getServiceTime();

else

{

rearCust = queues[shortest].peekRear();

finishTime = rearCust.getFinishTime() + nextCust.getServiceTime();

}

// set finish time and enqueue customer

nextCust.setFinishTime(finishTime);

queues[shortest].enqueue(nextCust);

custInCount = custInCount + 1;

// if needed, get next customer to enqueue

if (custInCount < numCustomers)

nextCust = custGen.nextCustomer();

}

else

// handle customer leaving

{

cust = queues[nextQueue].dequeue();

totWaitTime = totWaitTime + cust.getWaitTime();

custOutCount = custOutCount + 1;

}

} // end while

avgWaitTime = totWaitTime/(float)numCustomers;

}

}

//----------------------------------------------------------------------

// SimGUI.java by Dale/Joyce/Weems Chapter 5

//

// Simulates customers waiting in queues. Customers always enter

// the shortest queue.

//

// Input consists of simulation instance information:

// Minimum and maximum customer inter-arrival time.

// Minimum and maximum customer service time.

// Number of queues and customers.

//

// Assumes a friendly user, i.e., inputs are valid.

//

// Output is the average waiting time for a customer.

// Uses a graphical user interface.

//----------------------------------------------------------------------

import java.awt.*;

import java.awt.event.*;

import javax.swing.*;

import javax.swing.border.*;

import java.io.*;

import support.*;

public class SimGUI

{

// input text fields

private static JTextField minIATText;

private static JTextField maxIATText;

private static JTextField minSTText;

private static JTextField maxSTText;

private static JTextField numQueuesText;

private static JTextField numCustText;

// status Label

private static JLabel resultLabel; // label for status/result info

// Define a button listener.

private static class ActionHandler implements ActionListener

{

public void actionPerformed(ActionEvent event)

// listener for the button events

{

if (event.getActionCommand().equals("Simulate"))

{ // Handles Evaluate event.

float result;

Simulation sim = new Simulation

(Integer.parseInt(minIATText.getText()),

Integer.parseInt(maxIATText.getText()),

Integer.parseInt(minSTText.getText()),

Integer.parseInt(maxSTText.getText()));

sim.simulate(Integer.parseInt(numQueuesText.getText()),

Integer.parseInt(numCustText.getText()));

result = sim.getAvgWaitTime();

resultLabel.setText(" Average Wait Time: " + result);

}

else

if (event.getActionCommand().equals("Clear"))

{ // Handles Clear event.

resultLabel.setText(" RESULT ");

minIATText.setText("");

maxIATText.setText("");

minSTText.setText("");

maxSTText.setText("");

numQueuesText.setText("");

numCustText.setText("");

}

}

}

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

{

// Declare/instantiate/initialize display frame.

JFrame displayFrame = new JFrame();

displayFrame.setTitle("Queue Simulation Program");

displayFrame.setSize(350,300);

displayFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

// text boxes for input

minIATText = new JTextField("", 5);

maxIATText = new JTextField("", 5);

minSTText = new JTextField("", 5);

maxSTText = new JTextField("", 5);

numQueuesText = new JTextField("", 5);

numCustText = new JTextField("", 5);

// input/result labels

JLabel InArgLabel = new JLabel(" Input Arguments:", JLabel.LEFT);

JLabel minIATLabel = new JLabel(" Minimum Inter-Arrival Time", JLabel.CENTER);

JLabel maxIATLabel = new JLabel(" Maximum Inter-Arrival Time", JLabel.CENTER);

JLabel minSTLabel = new JLabel(" Minimum Service Time", JLabel.CENTER);

JLabel maxSTLabel = new JLabel(" Maximum Service Time", JLabel.CENTER);

JLabel numQueuesLabel = new JLabel(" Number of Queues", JLabel.CENTER);

JLabel numCustLabel = new JLabel(" Number of Customers", JLabel.CENTER);

resultLabel = new JLabel(" RESULT ", JLabel.CENTER);

// input/result panels

JPanel minIATPanel = new JPanel();

JPanel maxIATPanel = new JPanel();

JPanel minSTPanel = new JPanel();

JPanel maxSTPanel = new JPanel();

JPanel numQueuesPanel = new JPanel();

JPanel numCustPanel = new JPanel();

JPanel resultPanel = new JPanel();

// set input/result panel layouts

minIATPanel.setLayout(new FlowLayout(FlowLayout.LEFT));

maxIATPanel.setLayout(new FlowLayout(FlowLayout.LEFT));

minSTPanel.setLayout(new FlowLayout(FlowLayout.LEFT));

maxSTPanel.setLayout(new FlowLayout(FlowLayout.LEFT));

numQueuesPanel.setLayout(new FlowLayout(FlowLayout.LEFT));

numCustPanel.setLayout(new FlowLayout(FlowLayout.LEFT));

resultPanel.setLayout(new FlowLayout(FlowLayout.LEFT));

// add items to input/result panels

minIATPanel.add(minIATLabel);

minIATPanel.add(minIATText);

maxIATPanel.add(maxIATLabel);

maxIATPanel.add(maxIATText);

minSTPanel.add(minSTLabel);

minSTPanel.add(minSTText);

maxSTPanel.add(maxSTLabel);

maxSTPanel.add(maxSTText);

numQueuesPanel.add(numQueuesLabel);

numQueuesPanel.add(numQueuesText);

numCustPanel.add(numCustLabel);

numCustPanel.add(numCustText);

resultPanel.add(resultLabel);

// Simulate and Clear buttons

JButton simulate = new JButton("Simulate");

JButton clear = new JButton("Clear");

// Button event listener

ActionHandler action = new ActionHandler();

// Register button listeners.

simulate.addActionListener(action);

clear.addActionListener(action);

// Instantiate content pane and information panels.

Container contentPane = displayFrame.getContentPane();

JPanel mainPanel = new JPanel();

JPanel buttonPanel = new JPanel();

// Initialize main panel.

mainPanel.setLayout(new GridLayout(7,1));

mainPanel.add(InArgLabel);

mainPanel.add(minIATPanel);

mainPanel.add(maxIATPanel);

mainPanel.add(minSTPanel);

mainPanel.add(maxSTPanel);

mainPanel.add(numQueuesPanel);

mainPanel.add(numCustPanel);

// Initialize button panel.

buttonPanel.setLayout(new GridLayout(1,2));

buttonPanel.add(simulate);

buttonPanel.add(clear);

// Set up and show the frame.

contentPane.add(mainPanel, "North");

contentPane.add(buttonPanel, "Center");

contentPane.add(resultPanel, "South");

displayFrame.pack();

displayFrame.setVisible(true);

}

}

//---------------------------------------------------------------------

// SimulationApp.java by Dale/Joyce/Weems Chapter 5

//

// Simulates customers waiting in queues. Customers always enter

// the shortest queue.

//

// Input consists of customer information:

// Minimum and maximum customer inter-arrival time.

// Minimum and maximum customer service time.

// Followed by a sequence of simulation instance information:

// Number of queues and customers.

//

// Output includes, for each simulation instance:

// The average waiting time for a customer.

//----------------------------------------------------------------------

import java.util.Scanner;

public class SimulationApp

{

public static void main(String[] args)

{

Scanner conIn = new Scanner(System.in);

int minIAT; // minimum inter-arrival time

int maxIAT; // maximum inter-arrival time

int minST; // minimum service time

int maxST; // maximum service time

int numQueues; // number of queues

int numCust; // number of customers

String skip; // skip end of line after reading an integer

String more = null; // used to stop or continue processing

// Get customer information

System.out.print("Enter minimum inter-arrival time: ");

minIAT = conIn.nextInt();

System.out.print("Enter maximum inter-arrival time: ");

maxIAT = conIn.nextInt();

System.out.print("Enter minimum service time: ");

minST = conIn.nextInt();

System.out.print("Enter maximum service time: ");

maxST = conIn.nextInt();

// create object to perform simulation

Simulation sim = new Simulation(minIAT, maxIAT, minST, maxST);

do

{

// Get next simulation instance to be processed.

System.out.print("Enter number of queues: ");

numQueues = conIn.nextInt();

System.out.print("Enter number of customers: ");

numCust = conIn.nextInt();

skip = conIn.nextLine(); // skip end of line

// run simulation and output average waiting time

sim.simulate(numQueues, numCust);

System.out.println("Average waiting time is " + sim.getAvgWaitTime());

// Determine if there is another simulation instance to process

System.out.println();

System.out.print("Evaluate another simulation instance? (Y=Yes): ");

more = conIn.nextLine();

System.out.println();

}

while (more.equalsIgnoreCase("y"));

System.out.println("Program completed.");

}

}

AWT model

public class GlassQueue extends ArrayUnbndQueue

public class ArrayUnbndQueue implements UnboundedQueueInterface

public interface UnboundedQueueInterface extends QueueInterface

{

void enqueue(T element);

//Adds element to the rear of this quee.

}

public interface QueueInterface

{

T dequeue() throws QueueUnderflowException;

//Throws QueueUnderflowException if this queue is empty;

//otherwise, removes front element from this queue and returns it

boolean isEmpty();

//Returns true if this queue is empty; otherwise, return false

}