University of Waterloo
Final Examination
SAMPLE SOLUTION SET
Term: Fall
Year: 2005
Student Name
UW Student ID Number
Course Abbreviation and Number
Course Title
Sections
Instructor
Date of Exam
Time Period
Duration of Exam
Number of Exam Pages
Exam Type
Additional Materials Allowed
CS445/E&CE451/SE463
Software Requirements Specification and Analysis
001
Nancy Day
Thursday, December 22, 2005
Start time: 9:00 a.m.
End time: 11:30 a.m.
2 hours 30 minutes
14 pages (including this cover page)
Closed book
NO ADDITIONAL MATERIALS ALLOWED
• Write your name and student number at the bottom of every page.
• Write all solutions on the exam.
• Happy holidays!
Question Mark
1
Name
Max Marker
1
Question Mark Max Marker
4.4
4
2
13
5
8
3
8
6
10
4.1
7
7
8
4.2
13
8
7
4.3
13
9
8
Total
100
UW Student ID Number
(page 1 of 14)
2
(13 Marks) Short Answer: Concepts
1. (2 marks) Fill in the blanks:
Two good criteria for concept (class) diagrams are:
• low coupling
• high cohesion
2. (4 marks) For each of the following diagram types, check “yes” if it describes end-toend system behaviour (from a user input to a user output). Check “no” if it does
not.
yes no
√
Message sequence chart
√
System state diagram
√
State diagram for a class
√
Class diagram
√
Communication (collaboration) diagram
3. (2 marks) Fill in the blanks:
Inspections are more effective than testing for finding bugs because
inspections find the causes of errors,
whereas testing finds the symptons of errors.
4. (1 mark) What is the maximum time that a formal inspection meeting should last?
2 hours
Name
UW Student ID Number
(page 2 of 14)
5. (2 marks) What is the difference between active reviews and formal inspections?
Formal inspections have the author present his or her document. In an active reviews,
someone other than the author presents the document and answers questions about it.
6. (2 marks) What is the difference between simulation and formal validation?
Formal validation checks all behaviours of a model. Simulation only checks one behaviour (scenario) of a model.
Name
UW Student ID Number
(page 3 of 14)
3
(8 Marks) Consistency of UML Diagrams
Complete the concept-level UML sequence diagram below given the following concept-level
state diagrams. (The sequence diagram should stop when the system would require more
inputs before it can change state.) Any non-directed events are broadcast to all objects.
State diagram for Class C1:
State diagram for Class C2:
A
a/p:=createC2
r/p.f
r
B
/p.y
y/e
K
e/r
C
e/q:=createC2
G
D
/q.y
L
J
r/q.f
f/r
r/p.f
r/f
E
e/q.f
F
<<actor>>
:User
:C1
1: a
2: create()
P:C2
3: y
4: e
5: create() Q:C2
6: y
7: e
8: f
9: r
10: f
11: r
Name
UW Student ID Number
(page 4 of 14)
4
(37 Marks) SDL and UML Specification
Please read the problem description for Question #4 on the problem description handout.
Your solution must be consistent across all parts of this question. An event in the problem
description may be treated as a signal in SDL models, and vice versa.
4.1
(7 Marks) SDL Block Diagram
Assume that the system consists of one block called BabyMonitoringSystem. Show the block
diagram decomposing BabyMonitoringSystem into two processes: a process for the base
station software and a process for the remote unit software.
Block BabyMonitoringSystem
SIGNAL
BatteryLow, BatteryDead, BatteryReplaced,
TwoWay,OneWay,StartTalk,StopTalk,
PwrOn,PwrOff,
Noise,
Check,BabyAlarm,Ok,
SendSound(integer),
ReceiveSound(integer),
Baby
Beep, Alarm;
[Beep]
[Noise]
Base Station Hardware
Interface
Base
Base Station User
[SendSound,ReceiveSound]
Station
[BatteryLow,BatteryDead,
BatteryReplaced,
TwoWay,OneWay,
StartTalk,StopTalk,
PwrOn,PwrOff]
[Check]
BaseStationToRemote
[BabyAlarm, Ok]
Remote Unit Hardware
Interface
RemoteUnit
[PwrOn, PwrOff,
TwoWay,OneWay,
StartTalk, StopTalk]
[SendSound,ReceiveSound]
RemoteUser
[Alarm]
Name
UW Student ID Number
(page 5 of 14)
4.2
(13 Marks) UML State Diagram: Base Station
Draw a UML state diagram to model the behaviour of the base station process of the baby
monitoring software system. Show declarations of any variables in the SDL style.
PwrOff
Off
PwrOn
DCL
BS Integer;
BatteryDead
currentTime() > count + 10/
BabyAlarm
Baby Monitoring Mode
entry/SendSound(BS)
entry/count = currentTime()
Noise/count=currentTime()
Check/Ok
Alarm
Sounded
TwoWay
OneWay
Walkie-talkie Mode
StartTalk
receive
entry/ReceiveSound(BS)
talk
entry/SendSound(BS)
StopTalk
BatteryLow
Battery
High
Battery Low
/Beep
BatteryReplaced
Name
UW Student ID Number
(page 6 of 14)
4.3
(13 Marks) SDL Process Diagram: Remote Unit
Draw an SDL process diagram to model the behaviour of the remote unit process in the baby
monitoring software system. You may assume that time in SDL (durations) is measured in
seconds. An extra blank page follows if needed.
TIMER
CheckTimer,
WaitForOkTimer;
DCL RU Integer;
B
Power
Off
*
(Power Off)
OneWay
ReceiveSound(RU)
PwrOn
PwrOff
SET(NOW+10,CheckTimer)
ReceiveSound(RU)
Power
Off
SET(NOW+10,CheckTimer)
Baby
Monitoring
Mode
Baby
Monitoring
Mode
TwoWay
Walkie−
Talkie
Mode
StartTalk
CheckTimer
BabyAlarm
Alarm
B
Check
Wait for
PwrOff
SET(NOW+5,WaitForOkTimer)
SendSound(RU)
Wait
for
Ok
Sending
Sound
StopTalk
B
Ok
SET(NOW+10,CheckTimer)
ReceiveSound(RU)
Walkie−
Talkie
Mode
Name
Baby
Monitoring
Mode
UW Student ID Number
WaitForOkTimer
Alarm
Wait for
PwrOff
(page 7 of 14)
4.4
(4 Marks) Requirements and Specifications
For the baby monitoring software system, state whether each of the following sentences is
domain knowledge, part of the specification, or a requirement (using Jackson and Zave’s
definitions of these terms).
Note: Half of the marks for each question will be deducted for an incorrect
answer.
1. If the baby doesn’t cry for 10 seconds, the remote unit will sound an alarm.
Requirement
2. Two devices will not both try to talk in walkie-talkie mode at the same time.
Domain knowledge
3. When the system goes into the baby monitoring mode, it sends the SendSound signal
to the hardware interface.
Specification
4. The base station hardware is sensitive enough to detect the sound of a baby’s breath.
Domain knowledge
Name
UW Student ID Number
(page 8 of 14)
5
(8 Marks) UML Class Diagram
Santa’s making his list and checking it twice. He needs some software to help him out. Draw
a class diagram (conceptual model) for the system described below. In your class diagram,
show all attributes and operations contained in the description. Show all multiplicities and
non-obvious labels on the associations. You do NOT need to show navigability.
There is a set of elves who make toys. Every elf can make multiple toys. Every child has
a list of up to 3 toys that he or she would like. Every child receives a gift. Depending on
whether a child is naughty or nice, his or her gift contains one or two toys. There are three
kinds of toys: trains, dolls, and Xboxes. Every toy has a cost to produce the toy. The sum
of the costs is Santa’s yearly expenses.
requests
1
Children
+status
1
Elves
receives
1
1
0..3
makes
*
sum costs
Toys 1..2
1
Gifts
+cost
Yearly Expenses
Trains
Name
Dolls
UW Student ID Number
Xboxes
(page 9 of 14)
6
(10 Marks) Algebraic Specification
1. (9 marks) Write an algebraic datatype specification in SDL for a simple calendar
datatype. The calendar stores appointments, which are (event,day) pairs to indicate
that a certain event occurs on a certain day. Only one event can occur on a day in the
calendar. The datatype has the following operations:
• AddApt: given an event and a day, adds the appointment to the calendar if that
day does not already have an event in the calendar; otherwise do not change the
calendar.
• DeleteApt: given a day, removes from the calendar any event associated with that
day. It makes no change to the calendar if no event is scheduled for that day.
• LookupDay: returns the event associated with a particular day. It should not be
used if there is no event on that day in the calendar.
• Busy: returns true if there is an appointment in the calendar on the day passed
as an argument. It returns false otherwise.
• CountApts: returns how many appointments are in the calendar.
You may assume the types Event and Day exist. There is more room on the following
page if you need extra space. (Note: part 2 of this question is on the next page.)
NEWTYPE Calendar
LITERALS EmptyCalendar;
OPERATORS
AddApt: Event, Day, Calendar -> Calendar;
DeleteApt: Day, Calendar -> Calendar;
LookupDay: Day, Calendar -> Event;
Busy: Day, Calendar -> Boolean;
Count: Calendar -> Integer;
AXIOMS
FOR ALL d,d1,d2 in Day (
FOR ALL e in Event (
FOR ALL c in Calendar (
DeleteApt(d,EmptyCalendar) == EmptyCalendar;
DeleteApt(d1,AddApt(e,d2,c)) ==
if (d1=d2)
then AddApt(e,d2,c)
else DeleteApt(d1,c);
Name
UW Student ID Number
(page 10 of 14)
LookupDay(e,EmptyCalendar) == Error!;
LookupDay(d1,AddApt(e,d2,c)) ==
if (d1=d2)
then e
else LookupDay(d1,c);
Busy(d,EmptyCalendar) == false;
Busy(d1,AddApt(e,d2,c)) ==
(d1=d2) OR Busy(d1,c);
CountApts(EmptyCalendar) == 0;
CountApts(AddApt(e,d,c)) = 1 + Count(c);
Busy(d,c) ==> AddApt(e,d,c) == c;
)));
ENDNEWTYPE Calendar;
2. (1 mark) What is the canonical term in your datatype equivalent to completing the
following operations in this order:
(a) add the appointment (Soccer,Thurs)
(b) add the appointment (Baseball,Fri)
(c) add the appointment (Movie,Thurs)
(d) delete the appointment on Thurs
AddApt(Baseball,Fri,EmptyCalendar)
Name
UW Student ID Number
(page 11 of 14)
7
(8 Marks) Temporal Logic and Explicit Time Formalization
7.1
(5 Marks) Temporal Logic Formalization
Using the following predicates:
• awake(x) means baby x is awake
• smile(x) means baby x is smiling
formalize the following sentences in temporal logic. Show the types of any quantified variables.
1. Every baby smiles until he or she is awake.
∀x : Baby • smile(x) U awake(x)
2. For all babies, it’s always the case that eventually he or she will smile when he or she
wakes up.
∀x : Baby • ¤(♦(¬awake(x) ∧ °(awake(x) ∧ smiles(x))))
7.2
(3 Marks) Explicit Time Formalization
Using the same predicates as for part 1 of this question, formalize the following sentence
using explicit time. Show the types of any quantified variables. (You may change the types
of the predicates if necessary.)
1. Within every 10 second time period, some baby smiles.
∀t • ∃t1 • t − 5 ≤ t1 ≤ t + 5 ∧ ∃x : Baby • smiles(x, t1 )
Name
UW Student ID Number
(page 12 of 14)
8
(7 Marks) Validation
Circle “true” or “false” to say whether the following temporal formulae are true in the system
described by this UML state diagram. Being in a state is described by a proposition letter
of the name of the state (e.g., proposition A means the system is in state A). If the formula
is not true, provide a counterexample in the form of a sequence of states and events. If
multiple propositions are true in a single step in your counterexample, place them within set
brackets (e.g., the form of a counterexample is {A, J, e}, {A, G, e, f }, etc., which indicates
that propositions A and J and e are all true in the first step). If there is a repeated sequence
of steps in the counterexample, repeat it once and then use “. . . ”.
Note: Half of the marks for each question will be deducted for an incorrect
answer.
s
x
A
B
u
m
n
C
p
r
H
G
D
E
y
J
q
1. ¤(G ∨ E ∨ J)
true
2. ¤((G ∧ y) ⇒ °(A ∧ E))
false
Counterexample: {A, E, r}, {A, J, x}, {G, y}, {A, J}
3. ¤(E ∧ x ∧ (♦y) ⇒ (♦E))
true
4. (A ∨ B) U (m ∨ x ∨ n)
false
Counterexample: {E, A}, {E, A}, . . .
5. ¤(J W q)
false
Counterexample: {E, A}, {E, A} . . .
Name
UW Student ID Number
(page 13 of 14)
9
(8 Marks) Software Cost Estimation
Describe the steps of the software cost estimation process that uses COCOMO to estimate
effort and development time based on the requirements. Include any needed formulae. Include the units of measurement used. You do not need to include values for coefficients used
in the formulae.
Input: Requirements
1. Calculate {Pi } where Pi is the number of instances of the ith function type in the
requirements.
2. Determine the function points for the project from the inputs.
F P = a 1 P1 + a2 P2 + . . . a n Pn
where Pi are the number of instances of the ith function type, and ai is the weighting
associated with the ithe function type.
3. Determine KLOC in the implementation language based on the function points and
the KLOC/FP for each implementation language.
4. Calculate the effort and development time using the following formulae:
E = a × KLOC b × X (unit is person-months)
D = c × E d (unit is months)
Choose the coefficients a, b, c, and d based on whether the project is organic, semidetached or embedded. X is multipliers for project attributes.
Name
UW Student ID Number
(page 14 of 14)