Assignment 4, Final Project CSCI 204: Introduction to Computer Science II
Assignment 4: Discrete Event-Driven Simulations
April 9th, 2007
1 Objectives
•Use a Queue ADT
•Use software tools: JavaDoc
•Write documentation: technical specification
•Revise your work
•Practice basic team work
2 Important Dates
•Phase 1 due Monday 4/16 at 5pm
•Phase 2 due Monday 4/23 at 5pm
•Phase 3 due Tuesday 5/1 at 5pm
Since you are asked to implement different portions of the project in different phases, all three phases are required.
3 Overview
In a team of three or two, write a program to simulate the behavior of a web server with a waiting queue. The simulation
here is a Discrete Event Driven Simulation. The simulation is based on events happening in the system over time.
The web server tosimulate is called All-In-One-Server, orAIOS, which provides webservice, ftp service, and email
service over the Internet.
The AIOS waits for requests for service over the Internet. When a service request arrives, it can be one of three
types, WEB, FTP, or EMAIL. A WEB service takes a random amount of time between 3 to 5 minutes to complete;
an FTP service takes a random amount of time between 5 to 10 minutes to complete; while an EMAIL service takes
a random amount of time between 4 to 7 minutes to complete. The inter-arrival times between the WEB, FTP and
EMAIL traffic are random values of 10 to 28 minutes, 15 to 30 minutes, and 20 to 30 minutes, respectively. The FTP
and EMAIL do not generate other consecutive requests when they finish service. The WEB service, however, will
generate a new WEB service request with a probability of 30%, a new FTP service request with a probability of 20%,
and a new EMAIL service request with a probability of 15%. Note that a second-round WEB service will not generate
any further requests. You will need to make these two types of WEB events as different ones. One may generate further
service request, let’s call it WEB. One doesn’t, let’s call it WEBS for stop. The AIOS server can only service one
request at a time. If the server is servicing a request while another request arrives, the newly arrived request has to be
put into a waiting queue. When finishing serving a request, if any requests are waiting in the queue to be serviced, the
web server takes the first one off the queue and continues to serve the requests. If the waiting queue is empty, the web
server will be set idle.
The statistics your program need to collect include average waiting time, maximum waiting time, and counts for
each type of the service requests. The simulation will stop when the server has serviced 5,000 or more requests (all
types combined).
4 Some Technical Details
We will discuss some details here in this section.
Assigned April 9th, 2007
