cs 520hconboy/class/2021spring/cs... · 2021. 3. 2. · cs 520 theory and prac2ce of so4ware...

CS520TheoryandPrac2ceofSo4wareEngineering

Spring2021

So#warerequirements

March2,2021

In-classexercise1:AdvancedusesofGit

•  Due:WednesdayMarch3,2021,9AMEDT

•  Submission:– Couldeitherworkcollabora2velyasagroup(onyourownvideocall)

– Alterna2vely,couldworkindividuallyandwriteupasashareddocument(e.g.,overemail,GoogleDrive)

2

Homework1:ThreeinaRowgameapp

•  Due:ThisSaturdayMarch6,9PMEDT•  Codereview:OOdesignprinciples,bestprogrammingprac2ces

•  Architecture:MVC(Model-View-Controller)paRern

•  Design:ObserverpaRern•  Officehours:ThisThursdaya4erlecture,ThisFriday9:30–10AM

3

Today

•  RequirementsEngineering•  Specifica2on– Naturallanguage– FiniteStateAutomata(FSAs)– Specifica2onpaRerns

•  Finalproject

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RequirementsEngineering:Stakeholders

•  “individualsandorganiza2onswhoareac2velyinvolvedintheproject,orwhoseinterestsmaybeposi2velyornega2velyaffectedasaresultofprojectexecu2onorsuccessfulprojectcomple2on”

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[ProjectManagementIns1tute(PMI®),1996]

Example:ThreeinaRowgameapp(fromHomework1)

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•  Gameappplayers•  Gameappcompany:Developers,uppermanagement,usersupport,beta(user)testers

•  UIexperts:Humanfactors,HCI(Human-ComputerInterac2on)

•  Appstorecompany:Developersupport,Accoun2ngdepartment

•  Federalagencies:ADA(AmericanswithDisabili2esAct)

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RequirementsEngineering:Whatisaso#warerequirementsspecificaPon?

•  Documentstheassump2onsabout,featuresrequested,andbehaviorofagivenso4wareapplica2onexceptedbytheusers

•  Definesasetofrequirementsthatmustbesa2sfiedbytheso4wareapplica2on

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RequirementsEngineering:Twokeytypesofrequirements

•  Non-funcPonalrequirement:Aqualityconstraintontheso4wareapplica2on–  e.g.,extensibility,scalability,usability

•  FuncPonalrequirement:Anintended(orunintended)behavioroftheso4wareapplica2on–  e.g,TheThreeinaRowgamemustusetheMVCarchitecturepaRern.

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NOTE)Thereareothertypesofrequirementstodescribeassump1ons,features,andusagescenarios(e.g.,UMLusecases).

RequirementsEngineering:Twokeytypesofrequirements

•  Non-funcPonalrequirement:Aqualityconstraintontheso4wareapplica2on–  e.g.,extensibility,scalability,usability

•  FuncPonalrequirement:Anintended(orunintended)behavioroftheso4wareapplica2on–  e.g,TheThreeinaRowgamemustusetheMVCarchitecturepaRern.

10

NOTE)Thereareothertypesofrequirementstodescribeassump1ons,features,andusagescenarios(e.g.,UMLusecases).

RequirementsEngineering:Phases

1.  Elicita2on2.  Specifica2on3.  Analysis4.  Management

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Requirement Design Implementa2on


1.  Elicita2on2.  Specifica2on3.  Analysis4.  Management

12



1.  Elicita2on2.   SpecificaPon3.  Analysis4.  Management

13



•  ApplytheMVC(Model-View-Controller)architecturepaRern

•  FollowThreeinaRowgamerules

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SpecificaPon:Naturallanguage

•  Elicita2ono4enproducesrequirementswriReninnaturallanguage

•  Sample:1.  The‘ThreeinaRow’gameappmustusetheMVC

architecturepaRern.a.  Theremustbeasinglegamemodel.b.  Oncethenewgamemodeliscreated,thatmodelcanhaveits

statechanged.c.  Ifthegamemodelhasastatechange,thenitsgameviewmust

beupdated.d.  …

2.  …15

SpecificaPon:Disadvantagesofnaturallanguage

•  Naturallanguageiso4enambiguous•  Suchambiguitycanleadtohumanmisunderstandings

•  Theambiguityalsomeansverifica2on&valida2oncannotbecarriedoutbyapplyingautomatedtools,e.g.,– Tes2ng,modelchecking

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SpecificaPon:Disadvantagesofnaturallanguage

•  Naturallanguageiso4enambiguous•  Suchambiguitycanleadtohumanmisunderstandings

•  Theambiguityalsomeansverifica2on&valida2oncannotbecarriedoutbyapplyingautomatedtools,e.g.,– Tes2ng,modelchecking

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ThereforemathemaPcalnotaPons(e.g.,finitestateautomata)arecommonlyusedbecausetheyarerigorouslydefined

SpecificaPon:Finitestateautomaton(FSA)

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Eventsequenceoveranalphabet(meaningasetofevents)

Finitestateautomaton(FSA)

accept reject

or

FSA:Sample1a

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1 2

viol

gameModelNew

Theremustbeasinglegamemodel.

gameModelNew

gameModelNew

FSA:Sample1a

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1 2

gameModelNew


FSA:Sample1a

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1 2

gameModelNew


Eventsequence:[gameModelNew,gameModelNew]

FSA:Sample1a

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1 2

gameModelNew


Eventsequence:[gameModelNew,gameModelNew]

reject

FSA:Sample1a

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Eventsequence:[gameModelNew]

1 2

gameModelNew


FSA:Sample1a

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Eventsequence:[gameModelNew]

accept

1 2

gameModelNew


FSA:Sample1a

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Eventsequence:[]

1 2

gameModelNew


FSA:Sample1a

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Eventsequence:[]

1 2

gameModelNew


reject

FSA:Sample1b

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1 3

gameModelNew gameModelStateChange

2

gameModelStateChange

FSA:Sample1b

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1 3


Someeventsequencesthatareaccepted(i.e.posi2veexamples)?

2


FSA:Sample1b

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1 3


Someeventsequencesthatareaccepted(i.e.posi2veexamples)?[gameModelNew][gameModelNew,gameModelStateChange]

2


FSA:Sample1b

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1 3


Othereventsequencesthatarerejected(i.e.nega2veexamples)?

2


FSA:Sample1b

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1 3


Othereventsequencesthatarerejected(i.e.nega2veexamples)?[][gameModelStateChange][gameModelNew,gameModelNew]

2


FSA:Sample1b

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1 3


Oncethenewgamemodeliscreated,thatmodelcanhaveitsstatechanged.

2


FSA:FormaldefiniPonRepresentedasa5tuple:•  E:Thealphabetasasetofevents•  S:Thesetofstates•  T:Thesetoftransi2onswhereeachtransi2onisadirectededgefromasourcestatesoneventetotargetstatet

•  s0:Thestartstate•  A:Thesetofaccep2ngstates

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NOTE)Canbeautoma2callyconvertedtoaregularexpression

FSA:Disadvantages

•  NaturallanguageisgenerallymoreaccessiblethanFSAs

•  Handwri2ngFSAscanbeerrorproneand2meconsuming

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FSA:Disadvantages

•  NaturallanguageisgenerallymoreaccessiblethanFSAs

•  Handwri2ngFSAscanbeerrorproneand2meconsuming

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SpecificaPonpa[ernshavebeenidenPfiedofcommonlyoccurringintended(orunintended)behaviorsofso#wareapplicaPons

PropertyspecificaPonpa[ern:FormaldefiniPon

•  Consistsofa:– Scopecapturespartsofthetracewherethebehaviormustbesa2sfied(e.g.,Global)

– Behaviorcapturesoccurrenceororderofevents/proposi2ons(e.g.,BoundedexistenceofgameModelNew)

•  Providesmappingtovariouspropertyspecifica2onlanguages(e.g.,RegularExpressions,inthiscasegameModelNew)

36[hRps://maRhewbdwyer.github.io/psp/]

PropertyspecificaPonpa[ern:Scopes

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PropertyspecificaPonpa[ern:Behaviors

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Behavior

Occurrenceofevent/proposi2onA

Orderofevents/proposi2onsAandB (Chained)Response

(Chained)Precedence

Absence

Universality

(Bounded)Existence

PropertyspecificaPonpa[ern:Behaviors

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Behavior

Occurrenceofevent/proposi2onA

Orderofevents/proposi2onsAandB (Chained)Response

(Chained)Precedence

Absence

Universality

(Bounded)Existence

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PropertyspecificaPonpa[ern:PrecedencedescripPon

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PropertyspecificaPonpa[ern:Precedenceregularexpressions

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PropertyspecificaPonpa[ern:Precedenceregularexpressions

Propertypa[ernspecificaPon:Sample1b

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1 3


Oncethenewgamemodeliscreated,thatmodelcanhaveitsstatechanged.

2

gameModelStateChangeBehavior:gameModelNewmustprecedegameModelStateChangeScope:Globally

PropertyspecificaPonpa[erns:Disadvantages

•  Use80/20rule– MayneedtohandwriteFSAs

•  Don’tprovidesupportforreal-2meorprobabilis2cconstraints– Hasbeenextended[SeehRp://ps-paRerns.wikidot.com]

•  Designedforexperts– CanbedifficultfornovicestoselectamongpaRernsandcustomizethem

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PropertyspecificaPonpa[erns:Disadvantages

•  Use80/20rule– MayneedtohandwriteFSAs

•  Don’tprovidesupportforreal-2meorprobabilis2cconstraints– Hasbeenextended[SeehRp://ps-paRerns.wikidot.com]

•  Designedforexperts– Canbedifficultfornovicestoselectamongpa[ernsandcustomizetheselectedpa[ern

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PROPELtool:What?

•  Buildsonthepropertyspecifica2onpaRernsspecifiedasfinitestateautomata

•  ProvidesguidancetoselectamongthepaRernsandcustomizethatpaRern

46[hRp://laser.cs.umass.edu/tools/propel.shtml]

PROPELtool:Userinterface

47[AvailablefromhRp://laser.cs.umass.edu/release/]

Scope

Behavior

PROPELtool:DemonstraPon

Specifythefollowing:“Ifthegamemodelhasastatechangethenitsgameviewmustbeupdated”

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PROPELtool:SampleFSA1c

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Behavior:gameModelStateChangemusthaveresponsegameViewUpdateScope:Globally

PROPELtool:SampleDNL1c

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Finalproject:GroupandtopicselecPon

•  Formteamof4or5students•  Selectoneofthefollowing4topics:

1.  MSRminingchallenge:2020or20212.  Replica2onstudy3.  MLdevelopmenttoolkit4.  EleNa:Eleva2on-basednaviga2on5.  Proposedyourowngroupproject

•  Due:ThursdayMarch4,20219:00PMEDThRps://people.cs.umass.edu/~hconboy/class/2021Spring/CS520/finalProject.pdf