华东交大软件学院外教课程Lecture-9-Requirements-Specification

SoftwareEngineering

UsmanFarooq

sf_usman@

Goal(s)ofthislecture

Tounderstandsoftwarerequirementsspecification(SRS)Tounderstanddifferentnotationsfordocumentingrequirements.NaturalLanguageUseCasesTounderstandsomeexampleofLibraryManagementsystemSRS.2

RequirementsSpecificationThesoftwarerequirementsdocumentisalsocalledsoftwarerequirementsspecificationorSRS.Thisdocumentistheofficialstatementofwhatisrequiredofthesystemdevelopers.Itincludesbothadefinitionandaspecificationofrequirements.Note:“ItisNOTadesigndocument.Asfaraspossible,it shouldsetofWHATthesystemshoulddorather thanHOWitshoulddoit.”4

NotationsforWritingRequirementsDocumentTherearedifferentnotationsforwritingrequirementsspecificationdocumentlike:-NaturalLanguageUse-caseetc.5

NaturalLanguageExample#1Whatshouldbedocumented?R1:Thesystemshallplaythesound‘alarm’whenthedoorisopened.Id,Description,Title,Rationale,Source,Restrictions,Risks,FitCriterion/TestCase,Priority,Dependencies6

NaturalLanguageExample2R2:Onlyauthorizedpersonsareallowedtoenterthebuilding.R3:Thedoorbellbuttonshallbeblue,round,andwithadiameterof20mm.R2isagoal,R3isadetailedspecificationR3isinfactthreedifferentrequirements.7

NaturalLanguageExample3R4:Thesystemshallplaythesound‘alarm’whenthedoorisopened.R4:Thesystemshallplaythesound‘C:\alarm.wav’once,atthehighestvolumesettinginthemainspeakerforthebuildingwhenthedooropens.WrongRequirement8

NaturalLanguageExample4R5:Thesystemshallrespondquicklytouserinteraction.R5:Thesystemshallrespondtouserinteractionwithinmaximum2seconds,minimum0.2seconds,average1second(withaCPUloadof0.5).WrongRequirement9

NaturalLanguageExample5(AccessRights)R6:Therearefourclassesofusersinthesystem:Maintainer,Administrator,NormalUser,Guest.R7:AGuestUserisabletoenterareasX1,X2,andX3.R8:ANormalUserisabletoenterallareasinthebuilding.R9:AnAdministratorisaNormalUserwhoalsohavetherighttoadd/modify/deleteusersinthesystem.R10:AMaintainerisaGuestwhoisalsoabletoenterareaX99andperformbackups,viewsystemlogs,andadd/modify/deleteusers10

NaturalLanguageExample5(AccessRights)R6:UsersandtheiraccessrightsarelistedinTable11

NaturalLanguageExample6R11:Whenauserentersacorrectcode,thedoorshallopen.R11:Whenauserentersthecodeassociatedwithhim/heronkeypadK2thedoorD2shallunlockandremainunlockedfor30seconds.WrongRequirement12

NaturalLanguageExample7R12:Whenauserhasenteredthebuilding,thisshallberegisteredintheentrylogandtheuser’scomputershallbebooted.R12:Thesystemshallregisterintheentrylogwhenauserhasenteredthebuilding.R13:Whenauserhasenteredthebuilding,theuser’scomputershallbebooted.WrongRequirement13

NaturalLanguageExample8R13:NAEeventsshallyieldaBoTLtotheCiC.IntheDataDictionary:NAE:Non-AuthorisedEntryBoTL:BanditonTheLooseCiC:CommanderinChiefWrongRequirement14

NaturalLanguageExample9R14:Eachuserisissuedauniquemagneticcard.R15:Codesformagneticcardsaregeneratedusingthefourlastdigitsoftheuser’spersonalnumberExample10R16:Itisimportantcomputershouldplay‘alarm’,whendoorisopened.SeeR115

NaturalLanguageRequirementsCompleteCorrectFeasibleNecessaryPrioritizedUnambiguousVerifiableIn-linewithBusinessGoalsWehavediscussedtheexamplesinpreviousslides16

UseCasesStandardUMLUse-CasesEnterBuildingID:UC1Description:AuserentersthebuildingPreconditions:ThepersonisauserinthesystemPostconditions:Personhasenteredthebuilding17

ProjectCaseLibraryManagementSystemSRS

(SoftwareRequirementsSpecification)18ProjectCase(LibraryManagementSystem)1)GeneralUserFunctionalRequirements19ProjectCase(LibraryManagementSystem)1)GeneralUserFunctionalRequirements(Continuous)20ProjectCase(LibraryManagementSystem)1)GeneralUserFunctionalRequirements(Continuous)21ProjectCase(LibraryManagementSystem)2)LibrariansFunctionalRequirements22ProjectCase(LibraryManagementSystem)2)LibrariansFunctionalRequirements(Continuous)23ProjectCase(LibraryManagementSystem)3)System’sFunctionalRequirements24ProjectCase(LibraryManagementSystem)3)System’sFunctionalRequirements(Continuous)25ProjectCase(LibraryManagementSystem)3)System’sFunctionalRequirements(Continuous)26ProjectCase(Libra