軟件工程第9版部分習(xí)題答案

精品文檔習(xí)題參考答案Exercises(Homework):P251.3Whatarethefourimportantattributesthatprofessional謝謝閱讀softwareshouldhave?Suggestfourotherattributesthatmaysometimesbesignificant.精品文檔放心下載Fourimportantattributesaremaintainability,dependability,

performanceandusability.Otherattributesthatmaybesignificantcouldreusability(canitbereusedinotherapplications),distributability(canitbedistributedanetworkofprocessors),portability(canitoperate

onmultipleplatformse.glaptopmobileplatforms)inter-operability

(canwitharangeothersoftwaresystems).精品文檔放心下載Decompositionsofthe4keyattributese.g.dependabilitydecomposesto

security,safety,availability,etc.isavalidanswertothis

question.感謝閱讀2.1Givingreasonsforbasedthetypedeveloped,suggestthemostappropriategenericsoftwaremodelthat

mightbeusedasabasisformanagingthedevelopmentofthefollowing

systems:感謝閱讀?Asystemtocontrolanti-lockbrakinginacar感謝閱讀?Avirtualrealitysystemtosoftwaremaintenance

?Auniversityaccountingsystemthatreplacesexistingsystem

?Aninteractivetravelplanningsystemthathelpsusersplanjourneys

thelowestenvironmentalimpact精品文檔放心下載謝謝閱讀精品文檔放心下載1.Anti-lockbrakingsystemThisisasafety-criticalsystemsorequires

aofup-frontanalysisbeforeimplementation.Itcertainlyneedsa

plan-drivenapproachtodevelopmenttherequirementscarefully

analysed.Awaterfallmodelisthereforethemostappropriateapproach

toperhapsformaltransformationsbetweenthedifferent

developmentstages.謝謝閱讀精品文檔放心下載謝謝閱讀2.VirtualrealitysystemThisisasystemwheretherequirementswill

changetherewillanextensiveuserinterfacecomponents.

Incrementaldevelopmentwith,someUIprototypingisthemost

appropriatemodel.Anagileprocessmaybeused.精品文檔放心下載UniversityaccountingsystemThisisasystemwhoserequirementsare

fairlyell-knownwhichwillbeusedinenvironmentinconjunctionwithlotsof

otherstemssuchasaresearchgrantmanagementsystem.精品文檔放心下載Therefore,areuse-basedproachislikelytobeappropriateforthis.

InteractivetravelplanningsystemSystemacomplex精品文檔放心下載謝謝閱讀1歡迎下載。精品文檔interfacewhichmuststableandreliable.Anincremental

developmentapproachisthemostappropriateasthesystemrequirements

changeasuserexperiencethesystemisgained.精品文檔放心下載感謝閱讀謝謝閱讀2.4Suggestwhyitisimportanttomakeadistinctionbetweendevelopingtheuserrequirementsanddevelopingsystemrequirementsintherequirementsengineeringprocess.感謝閱讀精品文檔放心下載Thereisafundamentaldifferencebetweentheuserandthesystem

requirementsthattheyshouldbeconsideredseparately.

1.Theuserrequirementsareintendedtodescribethesystem’s

functionsfeaturesfromaperspectiveitisessentialthatusers

understandtheserequirements.Theyshouldexpressedinnatural

languageandmaybeexpressedingreattoallowsome

implementationflexibility.Thepeopleinvolvedintheprocessmustbeableto

understandtheuser’senvironmentandapplicationdomain.感謝閱讀精品文檔放心下載感謝閱讀謝謝閱讀2.Thesystemrequirementsaremuchmoredetailedthantheuser

requirementsareintendedtoaprecisespecificationthesystem

thatmaypartasystemcontract.Theymayalsousedinsituationswhere

developmentisoutsourcedandthedevelopmentteamneedacomplete

specificationofshouldbedeveloped.Thesystemrequirementsare

developedafteruserrequirementshavebeenestablished.感謝閱讀Excercises(Homework):P116精品文檔放心下載4.2，4.2Discoverambiguitiesomissionsinthefollowingstatementof

requirementsforpartofaticket-issuingsystem:

Anautomatedticket-issuingsystemsellsrailtickets.Usersselecttheir

destinationandacreditcardandapersonalidentification

number.精品文檔放心下載精品文檔放心下載精品文檔放心下載Therailticketisissuedandtheircreditcardaccountcharged.When

theuserpressesthestartbutton,amenudisplaypotentialdestinationsis

activated,alongamessagetothetoselect精品文檔放心下載adestination.Onceadestinationbeenselected,usersarerequested

totheircreditcard.精品文檔放心下載精品文檔放心下載Itsischeckedandtheisthenrequestedtoinputa

personalidentifier.Whenthecredittransactionbeenvalidated,the

ticketis感謝閱讀精品文檔放心下載Ambiguitiesandomissionsinclude:精品文檔放心下載2歡迎下載。精品文檔?acustomerseveralticketsforthesamedestinationtogether精品文檔放心下載ormusttheybeboughtoneatatime?精品文檔放心下載?customerscancelaifamistakebeenmade?

?shouldthesystemrespondifaninvalidcardisinput?

?Whathappensifcustomerstrytotheircardinbeforeselecting

adestination(astheywouldinATMmachines)?感謝閱讀感謝閱讀?Musttheuserpressthestartbuttonagainiftheywishtobuyanother感謝閱讀tickettoadifferentdestination?感謝閱讀?Shouldthesystemsellticketsbetweenthestationwherethe

machineissituatedanddirectconnectionsorshoulditincludeall

possibledestinations?謝謝閱讀感謝閱讀4.4Writeasetnon-functionalrequirementstheticket-issuing

system,settingitsexpectedreliabilityandresponsetime.感謝閱讀精品文檔放心下載Possiblenon-functionalrequirementsfortheticketsystem

include:謝謝閱讀1.Between0600and2300inanyoneday,thetotalsystemdowntimeshould

exceed5minutes.謝謝閱讀Between06002300inanyday,therecoverytimeafterasystem

failureshouldnotexceed2minutes.精品文檔放心下載謝謝閱讀3.Between2300and0600inanyoneday,thetotalsystemdowntimeshould

exceed20minutes.感謝閱讀Alltheseareavailabilityrequirements–thatthesevary

accordingtothetimeday.Failureswhenmostpeoplearetravelingare

acceptablethanfailureswhentherearefewcustomers.

4.Afterthecustomerpressesabuttononthemachine,thedisplayshould

beupdatedwithinseconds.精品文檔放心下載感謝閱讀感謝閱讀精品文檔放心下載感謝閱讀Theticketissuingtimeaftercreditcardvalidationhasreceivedshouldexceed10seconds.感謝閱讀精品文檔放心下載6.Whenvalidatingcreditcards,thedisplayshouldprovideastatus

messageforcustomersindicatingthatactivityistakingplace.Thistells

thecustomerthatthepotentiallytimeconsumingactivityofvalidation

isstillinprogressthatthesystemnotsimplyfailed.

7.Themaximumacceptablefailurerateforticketissuerequestsis1:精品文檔放心下載精品文檔放心下載感謝閱讀感謝閱讀Excercises(Homework):P143-144精品文檔放心下載5.2，5.5，5.6，5.75.2mightyouuseamodelofasystemthatexists?Explain感謝閱讀3歡迎下載。精品文檔itisnecessaryforsuchasystemmodeltobecompleteand

correct.Wouldthesamebetrueifyouweredevelopingamodelofasystem?謝謝閱讀精品文檔放心下載mightcreateuseamodelofasystemthatalreadyexistsfor

thefollowing謝謝閱讀1.Tounderstandanddocumentthearchitectureandoperationthe

existing感謝閱讀system.2.Toasthefocusofdiscussionpossiblechangestothat

system.精品文檔放心下載3.Toinformthere-implementationthesystem.精品文檔放心下載notneedacompletemodelunlesstheintentionistocompletely

documenttheoperationoftheexistingsystem.Theaimofthemodelinsuch

casesisusuallytohelpyouworkpartsthesystemsoonlytheseneedtobe

modelled.Furthermore,ifthemodelisusedasadiscussion

focus,youareunlikelytobeinterestedindetailsandsocanignorepartsofthesystem

inthemodel.感謝閱讀Thisistrue,inforsystemsamodel-based

approachtodevelopmentistakingplaceinwhichcaseacompletemodelis

required.Theothercircumstanceswhereyoumayneedacompletemodel

iswhenthereisacontractualrequirementforsuchamodeltobeproducedasofthesystemdocumentation.感謝閱讀感謝閱讀5.5Developasequencediagramshowingtheinteractionsinvolvedwhena

studentregistersforacourseinauniversity.mayhavelimitedenrolment,

sotheregistrationprocessmustincludechecksthatareavailable.

Assumethatthestudentaccessesanelectroniccoursecatalogtofindaboutavailablecourses.感謝閱讀Arelativelysimplediagramisallthatisneededhere.Itisbestnot

tobetoofussyaboutthingslikeUMLarrowstylesashardlyanyonecan

rememberthedifferencesbetweenthem.精品文檔放心下載4歡迎下載。精品文檔5.6carefullyatmessagesmailboxesarerepresentedintheemailsystem

thatyouuse.Modeltheobjectclassesthatmightbeusedinthe

systemimplementationtorepresentamailboxane-mailmessage.

謝謝閱讀5.7BasedonyourexperiencewithabankATM,anactivitydiagramthat

modelsthedataprocessinginvolvedwhenacustomerwithdrawscashfromthe

machine.謝謝閱讀5歡迎下載。精品文檔NoticethatIhavenotdevelopedtheactivitiesrepresentingother

servicesfailedauthentication.感謝閱讀Excercises(Homework):P173-1746.1,6.3,6.9精品文檔放心下載6.1Whendescribingasystem,explainwhyyoumayhavetodesignthesystem

architecturebeforetherequirementsspecificationiscomplete.精品文檔放心下載Thearchitecturemaytobedesignedbeforespecificationsarewritten

toprovideameansofstructuringthespecificationanddevelopingdifferentsubsystemspecificationsconcurrently,toallowmanufactureofhardware

bysubcontractorstoprovideamodelforsystemcosting.精品文檔放心下載6.3Explaindesignconflictsmightarisewhendesigningarchitecture

forwhichbothavailabilityandsecurityrequirementsarethemostimportant

non-functionalrequirements.感謝閱讀Fundamentally,toavailability,youneedtohave(a)replicated

componentsinthearchitecturesothatintheeventofonecomponent

failing,youcanswitchimmediatelytoabackupcomponent.Youalsoneedto

severalcopiesthedatathatisprocessed.Security

requiresminimizingthenumberofthedataand,whereverpossible,

adoptinganarchitecturewhereeachcomponentonlyknowsasmuch

asitneedsto,todoitsjob.Thisthechanceintruders感謝閱讀感謝閱讀謝謝閱讀6歡迎下載。精品文檔accessingthedata.Therefore,thereisafundamentalarchitecturalconflictbetween謝謝閱讀availability(replication,severalcopies)andsecurity(specialization,謝謝閱讀minimalcopies).Thesystemarchitecttofindthebestcompromisebetweenthesefundamentallyopposingrequirements.謝謝閱讀謝謝閱讀6.9UsingthebasicmodelofaninformationsystempresentedinFigure6.16,suggestthecomponentsthatmightbepartinformationsystem

that謝謝閱讀allowsuserstoviewinformationaboutflightsarrivinganddeparting

fromaparticularairport.感謝閱讀謝謝閱讀Studentsshouldconsiderthelevelsintheinformationsystemandshould

identifycomponentsthatmightbeincludedatlevel.Examplesofthese

components謝謝閱讀mightLevel1(Databaselevel)Flightdatabase;Flightstatusdatabase;Airportinformation;

Level2:(Informationretriev