Student Answers

7/28/2019 Student Answers

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O bject Oriented Software Engineering:P ractical softwa re de velopment using UML and JavaBy Timothy C. Le thbridge and Robert LaganireMcGraw-Hill 2001International ISBN 0-07-709761-0 US ISBN 0-07-283495-1

Public Answers to Selected Exercises Version 1.9 (August, 2002)

2002 Timothy C. Lethbridge and Robert Laganire

T he f ollowing c ontains answers to a subset of t he e xercises in the book, a long with e xplanations of some aspec ts of thea nswers. In some cases the provided answe rs ar e more detailed those that would be expected from students. Also note thatsome questions are subjective, so re aders may have responses diffe rent from those written here.

T he a nswers provided here are publicly available on the website so a s to enable students to prac tise. Generally spea king,the a nswers given her e are parts a of multi-part questions; in exercises with many par ts, a nswer s may a lso be given toparts c and e. The full set of answe rs is only available to instructors as a separate password-protec ted document.

W e update these answe rs fr om time to time, adding improved explanations, alternative a nswer s, and extra e xercises. Youc an c ontact us a t [email protected] .ca with suggestions. I tems w hich we plan to c omplete or a ugment a t a later date aremarked in green.

Please look at our web site (www.lloseng.com) for other information about this book, including: A knowledge base containing many of the basic fac ts fr om the book Videos of Tim Lethbridge presenting lec tures based on the book. The slides that have bee n prepared for profe ssors who teach using the book


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PUBLIC ANSWERS TO EXERCISES PA2

THESE ANSWERS SUPPORT THE BOOK OBJECT ORIENTED SOFTWARE ENGINEERING:

Chapter 1. Softw are and Software Engineering

E1.1 p. 5 Classifying software.a )*Custom; rea l-time.c )*G eneric; re al-time (but softreal-time).

E1.2 p. 10 Stake holder reactions to situations.

a )* The user may be disappointed, since he or she might be looking f orwar d to no longer having to do thisparticular type of work. On the other hand, he or she may be relieved about not being put out of work. The c ustomer may be disappointed at not being a ble to save money; he or she may also be surprised,

since many people believe that software systems are e asy to develop; they underestimate thec omplexity of tasks that are to be automated. The customer might consult some other softwar e engineerto obtain a second opinion.

The developers will probably move on to other work. The de velopment m anagers may be disappointed at not having the opportunity to do f urther work on

the project.

E1.3 p. 12 Prioritizing quality attributesa )*Reliability will be pa ramount for the spac ecraft software . It would be sad if the space craft did not make it

into orbit after a ll that time, a lthough no lives would be lost. Efficiency might be important since

processors from 20 ye ars e arlier are f ar slower than todays devices. U sability will likely not be a n issuesince the software w ill run autonomously and report a ny feedback to experts; f urthermore the softwarec annot be intera ctive since it takes considerable time to send signals to and from Pluto at the speed of light.Maintainability is a lso likely to be a minimal c oncern since this software is likely to only be used once.However, there remains the possibility that the software c ould be used on other systems, or will need to bec hanged as last-minute bugs are fixed.

c )*Maintainability will likely be the most important c oncer n since da ta pr ocessing softwa re te nds to evolve.Reliability will also be of c onsidera ble importance: Bill printing must be a ccurate, since it can be costly tor ectify mistakes. U sability of the bills themselves will be important bec ause ordinary people have tounderstand them. Efficiency should not be a concern.


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PA3 PUBLIC ANSWERS TO EXERCISES

2002 TIMOTHY C. LETHBRIDGE AND ROBERT LAGANIRE

Chapter 2. Review of object ori entation

E2.1 p. 32 Distinguishing among classes and instanc esT he c lass names in the following answers could vary slightly. The points in parentheses a re of lesserimportance, and are for those who have re ad Chapter 5.

a )*I nstance ofAutomobileCompany. (or perhaps justCompany)c )*Class, subclass ofPerson. (In Chapters 5 and 6, we w ill see that it might be better to make this a subcla ssofPersonRole)

e )*I nstance ofPerson.

E2.2 p. 33 Detec ting bad class name s and improving thema )*Bad. I s this a particular vehicle (which might better be c alled something like Locomotive, or

RollingStockConfiguration) or a scheduled r un (RegularlyScheduledRun) that c ould usea ny vehicle, or the run on a particular day (SpecificRun) ? We will discuss this kind of problem in moredetail in Chapter 6 in the context of the Abstraction Oc curre nce pattern.

c )*Bad. The word Data is inappropriate in a class name. Call it simply SleepingCar.e )*Bad. It should not be plural: Routewould be better .

E2.3 p. 33 Naming diffe rent classes derived from words with multiple English meanings.a )*Title: Describes published books independently of the number of c opies CopyOfTitle: or perhaps

LibraryItem: Represents physical books (as well as other things, such a s videos) that the library plac eson its shelves.

c )*RegularlyScheduledFlight: has a flight number, departure time, or igin and destination a nd isf lown every day; SpecificFlight: flies on a par ticular day.

E2.4 pp. 34-35 Identifying attributesI n this question a nd the next, there a re many alter natives, a few possibilities a re shown here. In pa rticularsometimes certain attributes could be represented as associations instead these are shown in parentheses.a )*name, description, (producer, distributer)c )*date, startTime, endTime, description, soundAlarmWhenStarting, (room)e )*callerNumber, calledPartyNumber, isConnected, startTime, currentCell,

signalStrength, totalCost

E2.5 p. 35 Identifying associationsa )*boughtFrom:ProductionCompany,producedBy:Producer, episodes:Episode,

leadActors:Actorc )*meetingRoom:MeetingRoome )*caller:CallParty, called:CallParty

E2.6 p. 35 Differentiating between variables and objectsa )*O bject

E2.7 p. 36 Identifying operations

I n the following, operations that w ould probably be polymorphic a re shown in italics, howe ver, exactly whichoperations are polymorphic would depend on the design.a )*get Ar ea, get Per i met e r Lengt h, get Poi nt s ,move, resize, rotate,

flipHorizontally, flipVertically

E2.8 p. 40 Identifying poor ge neralizationsa )*Bad: You c a nt say A Canadian dollars is a money; a lso CanadianDollars should be an instance of

Currency

c )*Probably OK .e )*Bad:Account12876would be instance ofBankAccount (or some subclass ofBankAccount)

E2.9 No public answer


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E2.10 pp. 41-42 Arranging potential classes into inheritance hierarchies (See also E5.21, p. 189)I n the following, the hier archies ar e shown using indented text to save spac e. Whether it would be appropriateto actually include all the classes in a given system would depend on the applica tions requirements. Ther e aremany possible va riations on these a nswers. Note: See also E5.21 for additional e xercises ba sed on theseproblems.

a )*I n this problem we c reate two separa te hierarchies,Vehicle and PartOfVehicle. These could a lso

have something likeMachine as a common superclass, although the problem suggested creating separa tehierar chies.

Vehicle

LandVehicle (Added)Car

SportsCar

Truck

Bicycle

AirVehicle (Added)Aeroplane

AmphibiousVehicle

PartOfVehicle

Engine

JetEngine

ElectricMotor

Wheel

Transmission

Vehicle could instead be divided into PoweredVehicle and UnpoweredVehicle; multipleinheritance could be then used for superc lasses of the vehicle leaf classes.

c )*Schedule (We will learn later that this may not be nee ded since the whole system stores the schedule)RegularlyScheduledTrip (Added as a superclass re presenting something that runs at a given time)

RegularlyScheduledExpressBus (renamed for clarity)BusRoute

ActualTrip (Runs at a given time on a given da y; could also be called Run)CharteredTrip (Renamed for clarity)ScheduledTrip (Added to properly complement unscheduledTrip)UnscheduledTrip (Runs on a route, but not at the normal time)

BusVehicle (Renamed from bus to distinguish diffe rent types of bus)LuxuryBus

TourBus

e )*Currency (Canadian Dollars and US Dollars are Instance s)ExchangeRate (Attributes or associations could befromCurrency, toCurrency, rate)FinancialInstitution ( Added)

Bank

CreditUnion

CreditCardCompany (Visa and MasterCard are instances)FinancialInstrument

ReusableFinancialInstrument ( Added)CreditCard

DebitCard

SingleTransactionInstrument ( Added)Cheque

BankAccount

Loan

ElectronicDevice ( Added)AutomaticTellerMachine (better than BankMachine)

BankBranch


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E2.11 p. 47 Describing how polymorphic implementations of certain shape operations would work.a )*translate: In SimplePolygon (as inherited by Rectangle and RegularPolygon), and

EllipticalShape (as inherited by Circle) , the method translate would move the center.

c )*getArea: I n Rectangle, the method getArea would return height * width. I n

RegularPolygon, it would compute the are a by dividing the polygon into numPoints individualtriangles (see the a nswer to E2.30 for the detailed a lgorithm). Once this ar ea is c alculated, the total area ofthe RegularPolygon would be c alculated by multiplying the a rea of eac h triangle by numPoints. I nCircle, the methodgetAreawould return pi *radius2.


E2.13 p. 47 Incorporating new classes into an e xisting class hierarchy that contains considerable polymorphism.a )*IsoscelesTriangle: One might think of making this a subclass ofArbitraryPolygon, howe ver

that w ould be inappropriate since you dont w ant it to inherit methods such as addPoint andremovePoint. A be tter solution is to make it a subclass ofSimplePolygon. As a ttributes you wouldhave to store thebaseLength and height, or else you could store one of the two values for angles andthe le ngth of one of the sides, letting the other a ngle value a nd side be computed w hen ne eded. Asmethods, you would need changeScale, setBaseLength, setHeight, getArea,getPerimeterLength, getVertices, getBoundingRect, getBaseAngle, getTopAngle,a nd perhapssetBaseAngle and setTopAngle.




E2.17 p. 49 Determining whe n dynamic binding is nee ded in a set of polymorphic methods.T his e xercise ha s turned out to be particularly useful to ensure students re ally understand the implications ofpolymorphism. Before assigning this exerc ise, it ha s proved to be necessary to e xplain the mater ial on pages48 and 49 particularly car efully, with several e xamples. N ote that the exerc ise has the assumption, that thec ompiler knows that no new c lasses or methods can be added to the hierarchy; it is worth r eminding studentsthat this is not generally true in Java ( you c an a dd a subclass unless the c lass is de clare d final, a nd youc annot declare a non-leaf class to be final) .a )*I nvoking getPerimeterLength on a Rectangle variable: No dynamic binding is needed since

Rectangle is a leaf class and so the var iable could only ever contain an instance of that class. The loca lmethod in Rectangle would alwa ys be called.

c )*I nvoking getBoundingRect on a Polygon variable: Dynamic binding w ould be needed, since e itherthe method in Polygon or the one in Rectangle might have to be executed depending on which classof object is placed in the variable at run time.

E2.18 p. 51 Researching products that claim to be object-oriented to determine if they really are.T he answer to this question will var y over time, depending on what products are available.

E2.19 p. 53 Using documentation to look up library classes and thus better understand a program.T his is a purely prac tical e xer cise. I ts purpose is to e ncourage students to get in the habit of usingdocumentation.







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E2.29 No public answer.




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Chapter 3. Basing software development on reusable technology

E3.1 p. 63 Researching resource s on the Internet that discuss aspects of reuse.T he answer to this question will var y since we b pages ar e continually being added, deleted and changed.

E3.2 p. 63 Analysing information about reuse.For discussion only.

E3.3 pp. 69-70 Determining the services that should be present in a frame work.a )*Reservation framework.

Add an instance of whatever that can be reserved (e.g. a book, a plac e on a flight, a sea t in a theatre) Add a n instance of w hatever the r eservation is made on behalf of (e.g. a library patron, a passenger, a

theatre-goer). Make a reservation Delete a reservation

E3.4 p. 70 Determining differentiating features of framework-based applications, as well as its hooks and slots.a )*Reservation framework.

Differ entiating features:- The classes of objects that can be reserved and their attributes, associations and other operations- The a ttributes of the r eservation itself, a nd perhaps subclasses r epresenting different types of

r eservation- The classes of objects that a reservation can be made on behalf of- The user interfa ce- Rules regar ding the reservation, such as who can make one, whether the item can be reserved, etc.

Hooks:- A function that would be called when a re servation is complete (e.g. to send an email)- An function to call when reservations are full that could be used, for example, to add a waiting list,

or to give some form of notification to the user.- A function called to load a reservation from a database.

- A function called to save a reservation. Slots:- There may be no slots in this syste m.

E3.5 p. 70 Determining the range of applications that might benefit from a framework.a )*Reservation framework.

A library system, where you can reserve items that are already checked out Reservation of sea ts on any kind of transportation system Reservation of entertainment tickets

E3.6 p. 70 Evaluating alternative approaches to designing a framework.a )*I f you started w ith a vertical framework for a f requent flier program, you w ould have a lot of facilities

a lready developed, some of which would be quite specific to the f r equent flier domain. The following

gives some ideas of the se rvice s, slots a nd hooks that might be provided; many va riations on this answera re possible.i. Services:

Maintenance of frequent f lier a ccounts to w hich points (miles) c a n be added a nd redee med ( i.e.a dding new accounts; deleting accounts)

Keeping of basic personal information (name, a ddress, points) about eac h fre quent f lier, w ithmethods to update this information (which would call the f irst hook below to a llow managing ofa dditional information)

Keeping of a log of flights to be used when producing r e ports ( would a lso be capable of rec ordingother transactions, e.g. points awarded for re nting a ca r).

Methods to add, delete and quer y the number of points in the account.


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Generic mec hanism, given two c ities, that w ould calculate how many points w ould be required tof ly between them for free for a given user. This would be called w hen c ustomers are doing queries,a nd a lso when a person actually books a free flight to determine how ma ny points to de duct. Thiswould call the first slot be low to do detailed calculations.

Generic mec hanism, given two cities, that would calculate how many points to credit to a pa rticularf requent f lier who pa ys for a ticket. It would be c alled when the user is ma king queries, and a lsowhen a person ac tually takes a flight, in orde r to credit points. This would call the second slot below

f or detailed calculations. Generic mec hanism that runs every month, c alling the slot (below) f or pr oducing r eports, and thehooks (below) for deleting inac tive accounts, and perhaps promoting users to different classes.

ii. Slots (code that must be provided) A method to evaluate rules regarding how many points are required to fly certain routes for free. A method to e valuate rules r egarding how many points are obtained from flying cer tain routes

( might be specific to certain classes of frequent flier, certain times, etc.) A method to produce a formatted pr intout of a frequent f liers a ccount (ea ch a irline may want to

make these appea r stylistically diff erent from other airlines). Note that instead of creating a slot, thisf unctionality could be lef t out of the fr amework entirely.

Note that the user interfac e would have to be provided, but w ould probably not actually a ppear a sslots in the basic system; the user inter face would be a separate subsystem that would simply ca ll theservices.

iii. Hooks (plac es where optional add-ons can easily be plugged in) Ability to manage additional types of information a bout frequent f liers ( e.g. work address, e mail,),

beyond the basic minimum information. Different airlines might want to keep diffe rent kinds ofinformation for use in marketing etc.

Ability to have differe nt classes of users (e.g. prestige users who have accumulated large numbers ofpoints)

Mechanism to delete a ccounts after a c ertain time period with no activity (this might be a ctivated bythe monthly run that prints reports)

Ability to a dd diffe rent kinds of points to be used for diff erent purposes (e.g. some a irlines, ina ddition to miles, also keep track of a separa te c ount of miles flown in first class; such points mighthave different rules, such as expiring after the end of a yea r).

E3.7 p. 70 Evaluating whether or not one should first develop a framework when designing an application.a )* Arguments in favourof developing a full frequent flier framework: De veloping the fr amework improves your overall design. Sinc e you would have to build flexibility into the

f ramew ork to allow it to be used by others, you would benefit from that flexibility when you have to makec hanges yourself.

As a consequence of the a bove, you would expect maintenance costs to be re duced; you would also expectto be able to respond faster to market-driven requirements changes.

You might be able to sell your framework to others, or to provide frequent-f lier services to other smallera irlines.

Should two airlines using the same f ramework decide to w ork together in a n alliance ( or to merge) theirsystems would be more compatible with eac h other, reducing costs.

E3.8 p.74 Evaluating whether an application should be designed as a client-server system or not.

a )*Word processors are not normally designed using a c lient-server ar chitecture . The f ollowing a re some ofthe re asons why not:

People typically use word processors on laptop computers or other machines that may not be connectedto any network.

Although pe ople do share word-processed data, most people work on their own local c opy and thenshare it when they ar e finished.

I t might be beneficial to allow a word processor to optionally connect to a se rver to do such things as loada nd save da ta, or to enable two people to e dit the same document c oncurrently. H owever it w ould still benecessary to ensure that the user could operate the program while not connec ted.


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E3.9 p.74 Determining the services to be provided by a server.a )*A n airline reservation server would be expected to do some of the following activities:

Maintain the list of flights along with basic details of each flight (a nd allow changes) Maintain the prices (and allow changes, special off ers etc.) Maintain the bookings (allow bookings to be made, changed and deleted) Allow people to query all of the above

E3.10 p. 79 Evaluating the balance of work on the client and server side of a system.a )*For an airline reservation system:

i. Server work: See exercise E3.9.

ii. Client work: Enter queries about available flights and display the results. Enter bookings Display and print itinerar ies

iii. I nformation tra nsmitted fr om server to client: Results of queries (r elatively simple text)

iv: I nformation tra nsmitted fr om client to server:

Simple commands and their arguments.v: How the clients work could be minimized or maximized: The c lient might be interacting with several differ ent r eservation systems, producing overa ll

itiner aries that would combine the r esults from several servers. A server c ould be developed toprovide this function interac ting with other servers and managing itinerar ies.

The client could, on the other hand, be given a lot of intelligence to work out itineraries and gooddeals. It could f ind the best price s, and even run a bidding mechanism that would try to get a irlineservers to give better dea ls.

The client could simply be a we b browser with no intelligence at all about the frequent flier domain.

vi: Network eff ects of changing the clients workload: Putting more intelligence into the server ( such as having the server interac t with other servers)

would have only a moderate e ffe ct on the quantity of information transmitted in the ne twork as a

whole. Adding e xtra intelligenc e to the c lient might result in lar ge numbers of queries being transmitted,a nd large number s of replies re turned. The client w ould need to pe rform these queries in or der tomarshal the information it needs to make decisions.

Having the client be come nothing more than a web browser, would probably increase networktraffic from the server to the client, since now the ser ver would have to transmit images a nd all theother information that will make the UI of the client look nice.

E3.11 p. 80 Writing protocols for a client-server system.T here are clearly many possible protocols for these systems; the level of complexity could become substantial.the following shows some basic sets of messages that could be exchanged.

a )*Airline reservation system. Note that a re al system can be extremely complex; the following repre sents asimplified view of the kinds of messages that such a system would need to exchange.

M essages to server Possible re plies to client

addRegularFlightnumber planeType effectiveDateconfirmFlightAddednumberflightNumberAlreadyExists

addFlightLegflightNumber origin leaveTime destination arriveTimeconfirmLegAdded

flightTimeConflictsWithAnotherLeg

deleteRegularFlightnumber effective DateconfirmDeletion

flightNumberDoesNotExist


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addFareClassfareCodeconfirmFareClass

fareClassAlreadyPresent

setFareorigin destination classCode startDate endDateconfirmFare

addBookingname date flight originCity destinationCity fareClassconfirmBookingc onfirmationNumber seatbookingCannotBeMade

reason

deleteBookingc onfirmationNumberconfirmBookingDeletion

bookingNotCancelledreasonconfirmationNumberInvalid

queryFlightAvailabilitydate origin destination fareClass earliestDepTime latestArrTimeavailableFlight date flightNumber fa reClassnoMatchingAvailableFlight

queryBookingsname dateconfirmBookingc onfirmationNumber seat

queryBookingsByNumberc onfirmationNumberbookingInfoflightNumber date name origin

destination fareClass seat

queryPassengersflightNumber date bookingInfoflightNumber date name origindestination fareClass seat


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Chapter 4. Developing requirements

E4.1 p. 106 Listing information to be consulted when performing a domain analysis.a )*Police information system

Police officers and staff (interviews, brainstorming and observing work)

Police training and proce dures manuals Documentation of existing software and equipment used by the police (including compe ting products) Books about police methods Similar information about related ac tivities such as court procedures, etc.

E4.2 p. 106 Writing a short domain analysis for a syste m.W e will not be providing a ny a nswers to this exercise since the a nswers will depend too much on theinformation consulted, the country in which the re ader resides, and the date the information is gathered.

E4.3 p.110 Defining and narrowing the scope of a system.I n this following answers, a r e asonably c omplete set of possible system f unctions is listed. The f unctions inbold a re the ones that represent the minimal r equirements of a first re lease. Of course, e a ch persons answerw ill be somewhat diff erent; however, the sample answers suggest the scope of good answers to this question.

( See E9.1 for additional exercises based on these systems)a )*Police information system

Managing personnel information about officers and staff (note that a generic personnel managementsystem could also be used to do this, although it would have to be hooked to the police system to enablesome of the other functions mentioned below).

Managing basic information about are as and events to be patrolled Facilitating the manual scheduling of the duties of officers and staff Automatically proposing schedules for some of the duties of officer s and staf f Managing basic information about each case being investigated Managing the documents that have to be wr itten regarding each case, and following each shift Genera ting statistics and trend information about crime rates etc. Managing detailed information about suspe cts, witne sses and other people relevant to cases Providing links to drivers licenses and other databases to help police find information Providing links to court and criminal rec ords

E4.4 p. 110 Giving precise problem statements, considering high-level goals.a )*T he ne w police information system will make opera tions of the police depar tment more e fficient by

r educing the time and effort re quire d to plan and e xecute work, as well the time required to enter a nd findinformation required in routine police work.

E4.5 p. 115 Describing functional re quirements of a system.T hese build on the answers to E4.3 and E4.4 above.a )*Police information systemT o be provided in a later version of this document

E4.6 p. 118 Classifying requirements into functional or non-functional.a )*F. Describes the c omputation to be perf ormed (some security requirements a re non-functional, but thisone seems to be in the functional ca tegory)

c )*N F. Constrains response time.

E4.7 p. 118 Rewriting requireme nts so they are verifiable. I n eac h par t of this questions, w e would expec t an answer similar to one of the bulleted points. Some of the

bulleted points show that there should be two or more separate requirements.a )*Constraint on te chnology to be used:

The C++ programming langua ge must be used A strongly typed, block-structured progra mming language must be used that does not allow unrestricted

a ccess to memory.


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c )*Constraint on availability and throughput - The system will accept connections 24 hours a day, every day, with a ma ximum downtime of 5

minutes a month, w hich can occur only between 12:30 a.m. a nd 1:30 a.m. North American EasternTime.

- W hen available, the system w ill a t a ll times be able to manage 200 simultaneous connections, a ndprocess 2000 transactions per minute.


E4.9 p. 119 Writing non-functional requirements.T hese build on the answers to E4.3 - E4.5 above.a )*Police information system

When the user is c onnected to the over a local a rea network, the system shall respond with completer esponses to all inputs within 0.5s at peak system load.

When the user is c onnected over a wireless connection a t 9600bps, the system shall respond withc omplete re sponses to all inputs within 3s at peak system load.

The system shall be c apable of handling 50 simultaneously c onnected user s, a nd 300 user interactions( events originating from users) per minute.

The system shall not consume more than 200MB of RAM while running at peak ca pacity. The system shall not consume more than 56Kbps of ba ndwidth per connected user (averaged over any

1s time per iod) The system shall a chieve a r eliability level of no more than 1 failure per 10 user hours, w ith none of

those failures rendering the system totally inopera ble. The system shall be available 99.9% of the time with no period of down time exceeding 2 minutes. The system shall be designed so that large numbers of a dditional f unctions c an be a dded with little

r eprogramming. The system shall be designed so that it c ould be adapted to the ne eds of other police departments with

minimal reprogramming. The server shall be a ble to run on a W indows 2000 ( or higher) equipped system, with a 1.4 G Hz or

f aster Intel processor, 300MB or more of RAM, and 15GB or more of disk space . The c lient software shall be a ble to run on E MP-4500 police car terminals, as w ell as on EMP-4500

e mulators running on desktop computers.

E4.10 p. 122 Practising interview techniques.T his is a purely prac tical exer cise.

E4.11 p. 124 Practising brainstorming techniques.T his is a purely prac tical exer cise.




E4.15 pp. 129-130 Describing the type of requirements document needed.

a )*Software controlling a manned spacecraft sent to Mars There would need to be a c onsiderable amount of detailed technical r equirements documentation.Technical terminology c ould be used since all readers would be expected to have a technicalbackground. There would probably initially be a very high-level description of the missions overa llobjectives used to obtain funding for the mission. Then there would be a requirements document for thehigh-level system requirements of the combined hardware- software system. Next, the system w ould bea lloca ted into hardwa re a nd software subsystems, w hich in turn would e a ch be divided into severa lsubsystems. At each level there w ould probably be genera l and detailed requirements documents. Ther ationale f or this level of detail is that a spacec raft is novel, is te chnically complex, w ill involve manydiffer ent people w ith diff erent types of exper tise to develop, is difficult or impossible to change oncelaunched, and is expensive (with high failure cost and hence a high level of required reliability).


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E4.16 pp. 135-136 Finding problems in requireme nts statem ents.a )*Simple inte rest calculation program

The re quire ments are not separa ted into individual points This is a handy utility is too informal I t is not clear whether the fields are updated upon every keystroke, or whether the user has to hit enter

or click on some button to cause an update of the fields. I t is not c lear whether the monthly payments a re a t the start or e nd of e ach month (this e ffects the

c omputation). ( The computations themselves ar e well-known by accountants, so it is legitimate to exclude them) There is no information about the platform on which the program runs, Maximum and minimum dollar amounts and interest rates that ca n be handled should be specified. Precision of calculations should be specified. What happens if the user enters invalid keystrokes? I t would be desirable to describe the user interface in a little more detail.

E4.17 p. 136 Rewriting requireme nts to rem ove defects.a )*Simple inte rest calculation program

Functional Requirements- W hen the system starts, a window appears, whose content and function is describe below.- The w indow has the title Simple Interest Calculation, as we ll as standard close a nd minimize icons

in the title bar.- The window has labels Principal:, Annual interest rate:, Interest paid at the end of e a ch month:.

The right edges of these are vertica lly aligned, and eac h is followed on the right by an input field- The principal and interest fields ar e capable of accepting 10 charac ters of input, the interest ra te field

is capable of containing 8 char acters.- The user may enter numeric values in each field; as each key is typed (including the delete key), the

other fields are updated instantly. An e mpty field is taken as having the value zero.- Editing the interest rate causes a change to the monthly payment.- Editing the monthly payment causes a change to the interest rate- Editing the principal causes a change to the monthly pa yment

- The user may use the mouse to move the insertion point or selec t characters in any field, as instandard Windows applications.- The system can handle dollar a mounts from - 999999.99 to 9999999.99, and interest rates from -

999.99% to 999.99%. The percent symbol is automatically added if the user does not specify it.- All ca lculations a re rounded to the neare st ce nt. Two de cimal plac es a re always shown in a ll three

places.- Any e dit to a f ield that would result in an invalid input, or a computed result that c ould not be

displayed in the other fields, will not be acc epted the system w ill beep and display a n e rrormessage at the bottom of the window describing the error. Err or messages include:

The largest value acc epted for is xxxThe smallest value ac cepted for is xxxInput must be numericInput is only ac cepted to two decimal points

A input value of xxx would result in an invalid value for Non-functional Requirements

- The pr ogram w ill r un on all Micr osoft W indows operating systems starting with W indows 95 andW indows NT 4.0 (on all CPUs of at least 33Mhz) .

- Response time will appear instantaneous to users.





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Chapter 5. Modelling with classes


E5.2 p. 160 Designing associations among classesN ote that the exercise says take car e to specify labels for the associations; however, we have only shownlabels w her e the default has would not suffice. I n many of the f ollowing, difference s in class names are

possible.a )*W e will see later on that aggregation c ould be used he re; however, a t this point in the book the f ollowing

would be a reasonable a nswer. Making the multiplicity on theVehicle end 0..1 might be e ven be tter,a llowing for wheels to exist on their own, without being attached to vehicles.

******Vehicle Wheel

E5.3 p. 160 Explaining the consequences of associations in terms of creation and destruction of instancesT his e xercise ha s several parts that a re strongly a nalogous to eac h other, a nd which turn out to be candidatesf or association classes, which are described on page 161.a )*AVehicle could exist, and then aWheelcould be created and associated with it; conversely, the wheels

c ould exist first. Similar ly, the order in which these associated objec ts ar e destroyed does not matter.

c )*U nder normal circumstances in the r e al world, a country exists over a longer period of time than a ny of itsheads of state. However, if we imagine a n information system storing biographical information, then aperson might be created in the system who later on is r e corded as the head of state of a c ountry. So therea re no nece ssary constraints on the order of creation or destruction of these instance s.

e )*T his is similar to parts b a nd d. T he Registration would be created after theMember and theActivity, a nd would have to be destroyed no later than these associated instances. ( In some

c ircumstances, theMember and theRegistration could be created together).

E5.4 p. 160 Reading associations in both direc tions.T he e xact phrasing of a nswers to this question w ill, of course, va ry c onsiderably. This exercise has provenparticularly valuable a t getting students to c heck their work a nd detec t err ors in their class diagra ms. Creatingthese answe rs e ven he lped us make improvements to our a nswers to E 5.2. Diffe rent answe rs to E5.2 would

r esult in differ ent answer s to this question.a )* AVehicle can have noWheels, or an unspecified number ofWheels. AWheelalways belongs to exactly oneVehicle.

c )* A Country has either zero or one known HeadOfState. A HeadOfState can head any number ofCountrys

e )* AMember can register in any number of activities (can have any number ofRegistrations) Each Registration involves registering exac tly oneMember in exactly oneActivity AnActivity can have an arbitrar y number ofRegistrations

E5.5 p. 162 Adding association classes.T he question doesnt require a list of a ttributes, but we show attributes be low to help explain the purpose ofthe association class.

a )*A r easonable association c lass might be c alled PlayingRecordor something similar. The a ttributesneeded would depend on the type of sport, but might includepositionPlayed, goalsScored,penalties and timeOnField

* ******Player SportGame

PlayingRecord

positionPlayedgoalsScoredpenaltiestimeOnField


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E5.10 No public answerE5.11 No public answer

E5.12 p. 175-176 Writing OCL constraints.a )*Referring to Figure 5.11, p. 164

context RecordingCategory inv:

subcategory->forAll(r |

self r)

E5.13 p. 178 Designing how operations would be performeda )*I n this example it is ambiguous whether getSiblings should include half siblings or just full siblings;

we assume the former.getSiblings (a method ofPerson) would be performed as follows:1 Obtain theparents (a Union), by following the association2. For the femalePartner of theUnion:

2.1 For ea ch of her Unions2.1.1 Put thechildr en of the Union in the result set

( excluding duplicates and the self object)3. Repeat step 2 for themalePartner4. Return the result set

c )*Step siblings a re children of a persons step-parent w hich are not half- siblings. To solve this problem wewill first define a method ofPerson called getStepParents, as follows:1. Obtain the parents (a Unionwe will ca llmainUnion) .2. For the femalePartner of themainUnion:

2.1 For ea ch of her Unions other than themainUnion

2.1.1 Put themalePartner in the result set3. Repeat step 2 invertingfemalePartner andmalePartner4. Return the result set

Now we can define thegetStepSiblings method ofPerson:1. For ea ch stepParent obtained by callinggetStepParents

1.1 Add each of the children of the stepParent to the result set2. Call getSiblings to obtain the set ofsiblings3. Subtra ct thesiblings and self from the re sult set4. Return the result set

E5.14 p. 178 Writing OCL constraints for the genealogical example.a )*context Person inv:

dateOfDeath = or dateOfBirth =

or dateOfBirth


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E5.18 p. 184 Making a preliminary list of classes by listing noun phrases in requirements.I n the f ollowing, we simply list a r easonable initial se t of classes ba sed on a f irst scan of the nouns in theproblem descriptions. Other lists are possible. Not all the nouns shown will end up in the final answers, shownin the answer to E5.20. Classes wher e there is some initial doubt are marked ?? .

a )*Bank account management system (p. 448) Service ?? BankAccount

Branch Client MortgageAccount, ChequingAccount, CreditCardAccount Property ?? CreditCard JointAccount ?? Privilege ?? Division, SubDivision ?? Manager, Employee ??

Nouns not on the list because they will probably not be classes in the system: System (because it is not part of the domain) OOBank (an instance) a ddress, branch number (attributes) a ccount number, balance, credit limit, overdra ft limit (attributes) interest rate, monthly fe e (attributes) husband, wife (information in an example only) c heque, insurance (possibly beyond the scope, may become classes later) Planning, Investments, Consumer, Consumer Division (instances) personal banker (association)


E5.20 p. 189 Adding generalizations or interfaces to a class diagram.a )*Bank account manageme nt system: See 5.21e for a related problem.

*

accountHolder

Customer

name

MortgageAccount

collateralProperty

Ac coun tTy pe

interestRatemonthlyFeechecksAllowedinsuranceAvailable

ChequingAccount

Branch

addressnumber

OrganizationalUnit

Person

Acco unt

numberbalance

creditOrOverdraftLimit

CreditCardAccount

expiryDate

CreditCard

name

subdivision

Employee

*

manager

0..10..1 *

worksFor

personalBanker*

1..*

*

0..1

*

1..2

The distinction betwe enAccountType andAccount is important (so that eac hAccount does notneed to store its own interest rate) . There is a good c hance, howe ver, that students will not make thisdistinction in their initial answers.

The following ar e some variations:


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A customer is not always a person, so the generalization here may need to be changed so the top class isLegalEntity, which has Customer as a subclass (or the generalization can be removed entirely)

There can be separate Department and Division classes, although the solution shown, usingOrganizationUnit is more f lexible). I t is important, howe ver, not to add a se parate class f or eac hdivision, as that would be very inflexible.

Each individual credit car d may have its own number . CollateralProperty andAddressmay be classes instead of simple attributes

You might add a separ ate Privilege class a ssociated toAccountType, instead of the a ttributeschecksAllowedand InsuranceAvalable.

E5.21 p. 189 Additional exe rcises in drawing class diagrams, based on E2.10 (p. 41).Since each of these lacks detail regarding the requirements, we ha ve ha d to suggest the attributes a nda ssociations that should be pre sent. Note that each of these repre sents only part of a f inal system manydetails (e.g. additional classes) have been omitted.

a )*Vehicles: W e a ssume data is being maintained for hobbyists inter ested in data a bout a wide var iety ofvehicles and their pa rts. In this answer, we decided to follow the pattern f ound in Figure 5.12 cre ating a

VehicleCategory class instead of modelling each type of vehicle a s its own c lass. Students whoc reated the c lass hierarchy in E2.10 might simply transcribe it here; however, it is a good learning exerc iseto show that although the hiera rchy of E 2.10 might have been good for preliminary domain modelling, thea nswer below is much more flexible (it allows new vehicle types to be added without extra programming).Note also that question E6.2 is related to this.

VehicleCategory

description

*

powerSource *

subcatgegory

isOfCategoryVehicle

namemanufacturer*

VehiclePart

descriptiontypicalNumber

*hasParts

*

*subparts

*

c )*Bus scheduling: We a ssume a system for a bus company that runs r e gular r outes a s well a s charters. Thishas much in common with the Airline system (see the answer to E5.26). Note the following points: The subclasses ofBusVehicle have been merged, a nd the a ttribute c ategory is used to determine

whether the bus is a luxury one or not. Although it w ould see m that TripOnRoute would have no distinguishing f eatures, a nd thus not nee d

to exist a s a separate class, in fac t it could c ontain the a bstract operation getRoute, w hich would beimplemented diff erently in its two subclasses.

I nf ormation about bus stops not included in this model, but would be ra ther important.


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RegularlyScheduledTrip

depTime

BusRoute

originrouteNumber

*

*BusVehicle

model

*

yearMade

TripOnRoute

Ac tu alTr ip

date

destination

normalRunningTiime

identificationNumber

category

CharteredTrip

startPoint

startTime

expectedReturnTime

charterer

ScheduledTrip UnscheduledTrip

*

e )*Financial institution: See 5.20a for a similar problem ( that a lso includes the notion of customer s whicha re omitted here ). Note the following points about this answe r: We have dec ided to ma ke BankAccount a kind ofFinancialInstrument; this is a bit diffe rent

f rom w hat we did in the a nswer to E2.10e, but has the a dvantage that it allows the denomination

a ssociation to inherit nicely. I t is well known that debit cards have PINs. Some have a rgued that credit cards dont. In f act they do but the PIN s are not used in some jurisdictions.

*

Currency

codeexchangeRate

FinancialInstitution

name

FinancialInstrument

Branch

nameaddress

ReusableFinancialInstrument

number

Cheque

CreditCard

creditLimitname

PIN

DebitCard

amountdatesequenceNumber

BankAccount

accountNumberbalanceoverdraftOrCreditLimit

Loan

monthlyPayment

CreditCardCompany

issuer

BankhasBranches

drawnAgainst

denomination

*

*

* connectedAccounts

1..*

*

*

E5.22 p. 192 Determining responsibilities for each class.I t is important that these be simple phra ses. Suitable classes for the responsibilities are given in pa rentheses. In

some cases the w ord singleton is used to indicate that the responsibility could be a dded to a singleton classnot shown in the a nswer to E5.20. There a re sometimes se veral c hoices for suitable classes; a ll suitablec hoice s are listed, with the suggested one in italics. The plus symbol indicates that there should be severalpolymorphic implementations in subclasses

a )*Bank account management system. Adding a new customer (singleton, static Customer) Changing details of a customer (Cus t o mer ) Opening an account (static A c c o u n t +) Crediting an amount to an account (A c c o u n t ) Debiting an amount fr om an account (A c c o u n t ) Changing the cre dit or overdraf t limit on an account (A c c o u n t )


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I ssuing a new credit card (Cr edi t Car dAcc ount ) Adding a new employee (Or gani z at i onal Uni t ) Changing details of an employee (Empl oy ee) Assigning a personal banker to a customer (Cus t o mer , Employee) Adding a new bra nch (singleton, staticBranch) Changing the addre ss of a branch (Br anch) Changing an employee s reporting relationship (Empl oy ee) Changing the divisional structure in the organization (Or gani z at i o nal Uni t) Adding a new acc ount type (singleton, staticAccountType) Changing details of an account type (Account Type)


E5.24 p. 194 Adding operations to a class diagram.T hese c ould be listed inside class boxes; however, we have just shown them as simple lists f ollowing e achc lass.a )*Bank account management system

Account

Account(overdraftLimit, accountType)credit(amount)

debit(amount)

changeOverdraftLimit(amount)

ChequingAccountChequingAccount(overdraftLimit, accountType)

MortgageAccountMortgageAccount(initialBal, accountType, propertyDescription)

CreditCardAccountCreditCardAccount(accountType)

addCard(name)

AccountTypechangeInterestRate(newRate)

changeMonthlyFee(newFee)changeChequingPrivilege(checksAllowed)

changeInuranceDetails(insuranceDescription)

Person(no operations at this level of analysis)

EmployeechangeName(name)

changeOrganizationalUnit(newOrganizationalUnit)

CustomerassignPersonalBanker(employee)

BranchchangeAddress(newAddress, newPhoneNumber)

OrganizationalUnitaddEmployee(name)changepParentUnit(newParentUnit)





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Chapter 6. Using design patterns

E6.1 p. 206 Applying the Abstraction-Occurrence pattern.a )*

PeriodicalIssuePeriodical *

namepublicationFrequency

issn

volumeNumberissueNumber

publicationDatenumPages




E6.5 p. 221-222 De termining the pattern(s) that would apply in specific design circumstance s.a )*Adapte r (in your inheritance hier archy crea te a n adapter class that whose methods delegate to those in the

c lass you want to reuse)

N ote, parts a also uses delegation, but this is not the dominant patter n her e.






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Chapter 7. Focusing on users and their tasks

E7.1 p. 232 Reflecting on the usability and usefulness of eve ryday software.T his exercise is highly subjective; answe rs will depend on the software chosen, the version of the softwar e andthe re aders personal experience with the software.

E7.2 p. 234 Determining the types of users who will use systems.a )*A n air traf fic c ontrol system would be used by highly trained a ir-traffic c ontrollers and their managers.

They would be using the system intensively throughout their w orking day. Some aspects of the systemmight also be used by pilots, government aviation authorities and airport administrators.

E7.3 p. 237 Writing use casesa )*T he sequence of opera tions could differ from bank to bank.

U se case: Pay bill at ATM.A ctors: Any member of the genera l public with a bank account and bills to pay (minimum likely age is

16)Goals: To efficiently and accurately pay his or her bill

Preconditions: The actor must have a n a ccount at the bank. The bank must a ccept the bill in questionf or pa yment. The a ctor must have their ba nk c ard a nd know their PIN. The actor must havesufficient funds in their account.

Steps:Actor actions System responses

1. Insert card 2. Prompt for PIN

3. Enter PIN 4a. Display list of transactions

4b. Prompt for desired transaction

5. Specify pay bill 6. Prompt for details of bill

7. Enter details of bill 8. Prompt to deposit bill using an envelope

9. Deposit bill 10a. Accept deposit

10b. Debit account

10c. Print receipt10d. Prompt to see if there is another transaction

11. Indicate no other transaction 12. Eject card

13. Take card 14. Display welcome message

Postconditions: The system has stored the bill physically, and has a record of the transac tion. The actorhas a receipt for the transaction.


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E7.4 p. 238 Draw ing use ca se diagramsa )*Library system (based on example 4.9, pa ge 126) W e give two answe rs f or this: The first does not use

genera lization, which had not yet be en discussed in the text in the context of use case diagrams. Thisdiagra m is excessively complex so would not be worth dra wing in a real software engineering project.

Search fo ritems by

title

Borrower

Search fo ritems by

author

Search fo ritems bysubject

Check outan item

Checkpersonal

information

Checkout Clerk

Librarian

Add anew item

Deletean item

Changean item's

information

Check in

an item

Renewan item

Recordfine

payment

Ad d aborrower

Update aborrower'sinformation

Place abook on

hold

Ac coun ting Sys tem

Obtain

overdue fineamount

The se cond version of the answe r uses generalization, showing how the diagra m can be simplified (fewe rlines)

Search f oritems by

title

Borrower

Search fo ritems by

author

Search fo ritems bysubjectCheck out

an item

Checkpersonal

information

Checkout Clerk

Librarian

Add anew item

Delete

an item

Changean item's

information

Check inan item

Renewan item

Recordfine

paymentAdd a

borrower

Update aborrower'sinformation

Place abook on

hold

Accou nt ing System

Obtainoverdue fine

amount


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E7.5 p. 240-241 Writing use cases for the car park system.a )*

U se case: Exit car park by paying using a debit card.Goals: To leave the parking lot after having paid the amount due using a de bit ca rdPreconditions: In a ddition to exit car park pre conditions: The driver must ha ve a vailable his or her

debit card and know the PIN. The driver must have sufficient funds in his or her bank account.R elate d use cases:

Specialization of: Exit ca r par kSteps:Actor actions System responses

1. Drive to exit barrier, triggering a se nsor. 2a. De tect presence of a car.

2b. Prompt driver to insert his or her card.

3. Insert ticket. 4. Display amount due.

5.1 Insert debit card. 6.1 Prompt for account (chequing/savings).

5.2. Specify acc ount. 6.2. Prompt for PIN.

5.3. Specify PIN. 6.3a. Debit account.

6.3b. Eject debit card.

6.3c. Prompt driver to take debit card.5.4. Remove debit card. 6.4. Raise barrier.

7. Drive through barrier, triggering a sensor. 8. Lower barrier.

Postconditions: In a ddition to Exit car park postconditions: The drivers bank a ccount has beendebited.


E7.7 p. 242 Listing use cases and prioritizing them.a )*A telephone answering machine.

Record outgoing message Record incoming message

Listen to incoming messages Skip back to pre vious message Erase a message Skip to next message Record a conversation

E7.8 p. 257 Creating error messages for a user interface.a )*T here are unlikely to be any er ror messages on this scre en!

E7.9 p. 257 Determining whether response time is adequate at a web site.T he a nswer to this exercise depends on the design of the web site chosen (and that web sites re sponse timemay change from time to time).

E7.10 p. 257 Preparing a paper prototype.T his a prac tical exercise with no spec ific right answer.


E7.12 p. 258 Performing heuristic evaluations of user interfaces.T he answers to this e xercise depend on the programs chosen, the versions of those progra ms, a nd the parts ofthe programs evaluated.

E7.13 p. 258 Performing a heuristic e valuations of a web site.T he answers will depend on the web site chosen.


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E7.14 p. 258 Having multiple people conduct separate heuristic evaluations.T his is another subjective exer cise.

E7.15 p. 259 Performing heuristic evaluation of a GANA prototype and updating the UI.T his is another subjective exer cise.

E7.16p. 260 Performing an ev aluation of a UI by observing use rs.T his is another subjective exer cise.


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Chapter 8. Modelling interactions and behaviour

E8.1 p. 273 Drawing sequence diagrams.a )*Library example: This assumes that there is a Library singleton class acting as a Faade.

borrow

foundBook:CopyOfBook

:Library

foundBook :=search(title) :Loan

[available] create


E8.3 p. 275 Drawing more collaboration diagramsT hese corre spond to the answers to E8.1

a )*L ibrar y example

GUI

2:borrow

foundBook:CopyOfBook

:Library

1:foundBook :=

search(title)

:Loan

3:[available] create


E8.5 p. 279 Determining the state the system would be in after a sequence of events.a )*I t would be in state Cancelled.

Rationale:

I nitial = Planned;openRegistration -> OpenNotEnoughStudents (classSize=0);requestToRegister -> OpenNotEnoughStudents (classSize=1);requestToRegister -> OpenNotEnoughStudents (classSize=2);cancel->Cancelled










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E8.14 p. 283-284 Drawing and extending state diagrams.a )*Jukebox.

do:play chosenselection

MusicPlaying

ProposeSelection AcceptingMoney

enterCoin/displayTotal

[enoughMoney]pressSelection

/returnChangeIfNecessary

enterCoin/displayTotal

[not enoughMoney]pressSelection/displayNotEnoughMoney

pressReturnMoney/returnMoney


P8.2 p. 291 Drawing state diagrams of OCSF and SimpleChata )*ConnectionToClient in the OCSF Framework: N ote that e vents such as setHost have not been

modelled here.

InitializingAcceptingMessages

ReadyToTransmitTerminating

IOException

exception/clientException

Running message/receiveMessageFromClient

sendToClient/send

close/clientDisconnected

/clientConnected


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Chapter 9. Architecting and designing software

E9.1 p. 299 Dividing a system into subsystems (see also E4.3, p. 110).T here will be severa l ways of dividing these into separ ate systems. T he following systems suitable f or ther equirements for are expressed as a simple hierarchical list.

a )*Police information systemUser interf ace layer/clientMain functional layer /server

Scheduling subsystemCase management subsystemPersonnel management subsystemStatistics subsystem (may not be implemented in ea rly releases)

Document repositoryDatabase subsystemSubsystem providing interf aces to other systems





E9.6 p. 312 Categorising aspects of designs according to the coupling the y exhibit.a )*Common coupling (all methods that ac cess the variables are coupled)

E9.7 p. 313 Determining ways to reduce coupling.a )*I t would be better to have methods getMinClassSize and getMaxClassSize available in

CouseSection this is probably a r easonable place to use static methods, even though we r ecommendin general that they be avoided. Acc ess to the static variables should not be public.


E9.9 pp. 321-322 Choosing an architecture, basing the decision on quality requirements.I n parts a and b, the objectives are not met by any of the a r chitectures; this raises some de bate since we haveto choose which requirements to relax; we really need further study and discussion with the stakeholders.

a )*Choose a rchitecture A , although a rchitecture C might also be a rea sonable c hoice further study isprobably needed. Rationale: Runs on windows: Clea rly eliminates D (A, B, C left) Works on a 30 Kbps c onnection or faster: Eliminates B a nd per haps eliminates A , however we will

leave A under consideration for now since it is close to this thre shold (A, C left) Works on a 500 MHz machine or faster: Clearly e liminates C. Leaving only ar chitecture A even

though it does not quite meet the highest priority objec tive: bandwidth efficiency.

E9.10 No public answerE9.11 No public answer



E9.14 p. 339 Designing the architecture of systems.a )*A corporate payroll system.T o be provided.


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Chapter 10. Testing and inspecting to ensure high qualit y


E10.2 p. 353 Determining equivalence classes for testing purposes.a )*Telephone number . Note that it is good prac tice in softwar e engineer ing to not require telephone number s

to be in any par ticular format; this is because telephone numbe r formats can change over time, and because

f ormats differ f rom c ountry to country. A lso, people nee d to enter strings such a s ext to spec ify a ne xtension; there fore in the following we are being very liberal a bout w hat c ould be e ntered. You mayc hoose to be more restrictive.

Equivalence classes of valid data1 Any string of printable ASCII charac ters (including letters, numbers and special symbols)

Equivalence classes of invalid data2 The empty string (assuming the input is required)

c )*A time zone (numeric or alphabetical)

Equivalence classes of valid data:1 Any se quence of three upper-case letters (time z ones can be specified in many different ways

depending on the country; we ar e thus being liberal about allowed input)2 A string of the format shh[:]mm, wheres can be + or -,hh can be 00 to 14 (time zones nea r the date line can sometimes be greater than 12 hours from UTC)mm can be 00 or 30

Equivalence classes of invalid data:3 An empty string (assuming input is required)4 A string of length 1 or 25 A numeric time zone without the + or -6 A numeric time zone where the hour is greater than 147 A numeric time zone where the minutes range fr om 01 to 298 A numeric time zone where the minutes are other than 00 or 30

9 A sequence of alphabetic charac ters of length greater than 310 A character string mixing digits and letters12 A character string with characters other than digits, letters or :, + and - in the appropriate spots.

E10.3 p. 355 Determining equivalence classes when there are multiple inputs.T he following also incorpora tes the answe r to E10.4 (mar ked - Boundary cases)

a )*Personal information formDate of Birth: W e will consider this a s three separ ate inputs with a re quire d format of yyyy/mm/dd; you

may have picked a different format.Year1 Valid: integers from 1880 to 9999 (Assume this is a system for people alive at the time the system is

used

- Boundary cases: 2000, 2001, 1880, 99992 I nvalid: Integers from 0 to 99 (we treat this a s a separa te c ase since there may be some code thatincorr ectly handles 2-char acter dates, which we have dec ided not to allow)- Boundary cases: 0, 1, 99

3 I nvalid: Integer s from 100 to 1879- Boundary cases: 100, 1879

5 I nvalid: Empty string6 I nvalid: String with non-numeric characters

Month1 Valid: 01 to 12


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- Boundary cases 01, 122 I nvalid: 1 to 9 (assume we explicitly require two digits)

- Boundary cases 1, 93 I nvalid: 00 and 04 I nvalid: 13 to 99

- Boundary cases 13, 995 I nvalid: Empty string6 I nvalid: String with non-numeric characters

Day1 Valid: 01 to 28

- Boundary cases 01 and 282 Valid: 29 in February of a leap year , or in any othe r month a ny year.3 I nvalid: 29 in Fre bruary of a yea r other than a leap year.4 I nvalid 30 (in February)5 Valid: 30 (in some month other than February)6 I nvalid: 31 (in a 30-day month or in February)7 Valid: 31 (in a 31-day month)

8 I nvalid: 32-99- Boundary cases 32, 999 I nvalid: 00 and 010 I nvalid: 1 to 9 (2 characters required)

- Boundary cases 1, 911 I nvalid: Empty string12 I nvalid: String with non-numeric characters

Street Address:Valid: Character strings of length 2-40 (assumed limits) c ontaining upper a nd lower c a se c haracters,

numbers, comma, period, hyphen, single spaces, acce nts and diacriticalsBoundary ca se: Strings of length 2 and 40

I nvalid: Character strings containing non-printable character s

I nvalid: Character strings with more than one embedded spaceI nvalid: Strings of length 0-1

City, Country and Postal codeSame as street address, except that country and postal code can have 0 characters

Home Telephone NumberValid: Empty stringValid: String of character s including digits, +, ( ), -, x and spaceI nvalid: Other strings of character s

E10.4 p. 355 Determining boundary value s.See the lines ma rked boundary cases in the answer to E10.3


E10.6 p. 358-359 Tables of conditions for testing purposes.a )*Message forwarding

To be provided.


E10.8 pp. 365-366 Classifying and te sting for numerical defects.a )*A ssuming a floating point value will be exactly equal to 3.0, when it might be slightly different fr om this.


30/31





E10.11 p. 372 Designing stress and unusual-situation tests.a )*A new web browser

Loading a truly massive we b page full of complexity. Loading a web page containing a large amount of JavaScript. Loading a web page containing severa l large Java applets. Loading a web page full of html errors Loading a web page with obsolete html constructs Loading a web page with the latest complex html and cascading style sheet constructs Loading a web page that contains an extre mely large number of levels of nested html tags. Loading a web page containing tables with an extremely large number of columns and rows. Loading a web page demanding a lot of width of the resulting output Loading a very large web page that contains a large number of embedded objects. Testing the browser on an extre mely slow connection. Loading a very large number of web pages at once in multiple windows. Running on a var iety of differe nt versions of the target operating system.

Running on a machine with too little memory Running on a mac hine with too little disk spac e for caching purposes. Loading random pages over and over again for a long time (using a driver) Running on a ver y small screen Dealing with repeated failures of connec tions

E10.12 p. 376 Writing test cases.a )*Message forwarding

To be provided.



E10.15 p. 387 Conducting code inspections.T his is a purely prac tical exer cise


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Chapter 11. Managing the software process.

E11.1 p. 401 Reviewing group work in orde r to improve process.T his is pra ctica l work only



E11.4 p. 419 Creating a team structure for different software projects.a )*Replac ement of the income tax system of a c ountry ( unless the country is a tiny island nation) w ould be a

very big undertaking, requiring hundreds of pe ople. Some kind ofhierarchy would certainly be r equired.There would probably be a group of system a rchitects and over all projec t planners w ho would divide thesystem into its parts, and plan the inter faces a mong the parts. Then there w ould be a variety of sub-projec ts. Some of the sub-projects might be managed using the c hief- programmer or e goless style.





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