CS270 Winter 2004, Assignment #2
Assigned: Tuesday January 27, 2004
Due: Tuesday February 10, 2004 in class
Explain the difference between BPA, BPI, and BPR? (1 mark for each distinction, total of 3 marks)
What is the purpose of writing use cases? (1 mark)
What is DFD decomposition? What is DFD balancing? How do you determine to what level a DFD should be decomposed? (1 mark for each, total of 3 marks)
Explain the difference between a syntax error and a semantics error. Which is usually the most difficult to find and fix? Why? (1 mark for each definition, 1 mark for the difficulty, total of 3 marks)
Explain the following terms. Use layperson’s language as though you were describing them to a user: a) process; b) data flow; c) data store; d) external entity. (4 marks)
What is the parent process for process 3.2.1? 4.3.2.3? 1.2? (3 marks)
If you had to select an identifier for an employee entity, what three options do you have? (3 marks)
(a) Given the following, create a context-level DFD (using Gane and Sarson) for a university library system.
(1 mark for each entity, 1 mark for each data flow, total of 12 marks)
The system must record the books owned by the library.
The library manager will update this list of books on a regular basis.
The system must record who has borrowed what books, and which books have been returned.
Before someone can borrow a book, they must show a valid ID card that is checked to ensure that it is still valid against the student database maintained by the Registrar’s Office (for student borrowers), the faculty/staff database maintained by the Personnel Office (for faculty/staff borrowers), or against the library’s own guest database (for individuals issued a “guest” card by the library). The system must also check to ensure the borrower does not have any overdue books or unpaid fines before he or she can borrow another book. Every Monday, the library prints and mails postcards to those people with overdue books. If a book is overdue by more than two weeks, a fine will be imposed.
Sometimes books are lost or are returned in damaged condition. The manager must then remove them from the database and will sometimes impose a fine on the borrower.
(b) Create a Level-0 DFD for the same system.
(20 marks)
Create an ERD from the following information: (using IDEF1X)
One desk has zero or more drawers.
One drawer belongs to exactly one desk.
One drawer has exactly one stapler.
One stapler belongs to only one drawer, but doesn’t have to belong to any drawer.
One desk can have zero or more computers on it.
One computer can sit on only one desk, but doesn’t have to sit on a desk at all.
One computer can have one or more users.
One user can have one or more computers, but not all users are assigned to a computer.
One computer can have one or more hard disks.
One hard disk is built into one and only one computer.
A computer has exactly one monitor, and a monitor belongs to exactly one computer.
For each desk, we want to keep track of a Desk ID, Desk Type, and Desk Size.
For each drawer, we want to keep track of a Drawer ID and Drawer Size.
For each stapler, we want to keep track of a Stapler ID and Stapler Model.
For each computer, we want to keep track of a Computer ID, Computer Name, CPU type, CPU Speed, and RAM size.
For each monitor, we want to keep track of a Monitor ID, Monitor Size, and Monitor Model.
For each Hard Disk, we want to keep track of a Hard Disk ID, Hard Disk Size, and Hard Disk Model.
For each User, we want to keep track of a User ID, User Name, and User Phone Number.
(1 mark each of 7 entities, 1 mark each of 6 relationships, total 13 marks)
Total 65 marks