análise de sistemas (as) - departamento de informáticangarcia/aulas/asi1213/ubi asi 1213 aula...

JoãoPauloFernandes,[email protected],[email protected]

AnálisedeSistemas(AS)

AnoLecDvo2012/2013*1ºSemestre

CursodeLicenciaturaemTecnologiaseSistemasdeInformação

UNIVERSIDADEDABEIRAINTERIORFaculdadedeEngenhariaDepartamentodeInformáDca JoãoPauloFernandes,[email protected]

Aula3

1


Previously...

Contentadaptedfrom

SystemsAnalysisandDesignwithUML,4thEdiDonInternaDonalStudentVersion

AlanDennis,BarbaraHaleyWixomandDavidTegarden,

Wiley,2012


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SystemsDevelopmentLifeCycle(SDLC)

Planning

Analysis

Design

ImplementaDon



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SystemsDevelopmentLifeCycle(SDLC)

Theprocessconsistsoffourphases

Eachphaseconsistsofaseriesofsteps

Eachphaseisdocumented(deliverables)

PhasesareexecutedsequenDally,incrementally,iteraDvelyorinsomeotherpa`ern



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QuesDonstobeAnsweredPlanningphase

Whyshouldwebuildthissystem?

Whatvaluedoesitprovide?

Howlongwillittaketobuild?

AnalysisphaseWhowilluseit?

Whatshouldthesystemdoforus?

Where&whenwillitbeused?

DesignphaseHowshouldwebuildit?



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SDLC:ThePlanningPhaseProjectIniDaDon

Develop/receiveasystemrequestConductafeasibilityanalysis

• Technicalfeasibility• Economicfeasibility• OrganizaDonalfeasibility

ProjectManagement(aherapproval)Developtheworkplanandproduceaprojectplan

Stafftheproject

Monitor&controltheproject



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SDLC:TheAnalysisPhaseDevelopananalysisstrategy

Modelthecurrentsystem

Formulatethenewsystem

GathertherequirementsDevelopasystemconcept

Createabusinessmodeltorepresent:• Businessdata

• Businessprocesses

Developasystemproposal



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SDLC:TheDesignPhase

Developadesignstrategyandproduceasystemspecifica>on

Designarchitecture(sw,hw,network)andinterfaces(userinterfaces,menus)

DevelopdatabasesandfilespecificaDons

Developtheprogramdesigntospecify:Whatprogramstowrite

Whateachprogramwilldo



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SDLC:TheImplementaDonPhase

ConstructthesystemBuildit(writetheprogrammingcode)

Testit

InstallsystemTraintheusers

Supportthesystem(maintenance)



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SDLC:MethodologiesMethodology:aformalizedapproachto

implemenDngtheSDLCFormalstandardsusedbygovernmentagencies;internally

developedbycompanies;developedandsoldasaproduct,…

Categories(Business)ProcessorientedDatacenteredObject‐orientedStructuredRapidacDondevelopmentAgiledevelopment



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ClassesofMethodologiesStructuredDevelopment(~1980)

WaterfallDevelopment(detailed,butlengthy)ParallelDevelopment(faster,butwithincreasedintegraDonefforts)

RapidApplicaDonDevelopment(~1990)(hardtomanageuserexpectaDons‐>growing#requirements)

PhasedPrototyping

AgileDevelopment(sDllunderdevelopment!Programming‐centric,modelinganddocumentaDonoverheadsareeliminated)

eXtremeProgrammingSCRUM



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TheSystemsAnalyst:SkillsAgentsofchange

IdenDfywaystoimprovetheorganizaDon

MoDvate&trainothers

Skillsneeded:Technical:mustunderstandthetechnology

Business:mustknowthebusinessprocesses

AnalyDcal:mustbeabletosolveproblems

CommunicaDons:technical&non‐technicalaudiences

Interpersonal:leadership&management

Ethics:dealfairlyandprotectconfidenDalinformaDon



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AnExpensiveFalseStartA real‐estate group in the federal government cosponsored a data wharehouse with the ITdepartment.Aformalproposalwaswri`enbyITinwhichcostswereesDmatedat$800,000,theproject duraDon was esDmated to be eight months, and the responsibility for funding wasdefinedasthebusinessunit’s.

The IT department proceeded with the project before it even knew if th project had beenaccepted.

Theprojectactuallylastedtwoyearsbecauserequirementsgatheringtookninemonthsinsteadofoneandahalf,theplanneduserbasegrewfrom200to2,500,andtheapprovalprocesstobuytechnology for the project took a year. Threeweeks prior to technical delivery, the IT directorcanceledtheproject.ThisfailedendeavorcosttheorganizaDonandtaxpayers$2.5million.

a) Whydidthissystemfail?b) Whywouldacompanyspendmoneyand>meonaproject

andthencancelit?c) Whatcouldhavebeendonetopreventthis?


IntroducDonto

Object‐OrientedSystemsAnalysisandDesign

withUML

Contentadaptedfrom

SystemsAnalysisandDesignwithUML,4thEdiDonInternaDonalStudentVersion

AlanDennis,BarbaraHaleyWixomandDavidTegarden,

Wiley,2012


14


CharacterisDcsofObject‐OrientedSystems


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Classes&Objects

Object(instance):instanDaDonofaclass

A`ributes:informaDonthatdescribestheclass(Dpicallyprivate)

State:describesitsvaluesandrelaDonshipsatapointinDme

aStudent:Student

‐ Maria‐ 5thAvenue‐ 333333‐ {AS,BD,SO}

Student

‐Name‐Address‐ID‐CourseList

‐name()‐addCourse(Course)

InstanDaDon




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Methods&MessagesMethods:thebehaviorofaclass

Messages:informaDonsenttoanobjecttotriggeramethod(procedurecall)

aStudent:Student


AddSItocourselist




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EncapsulaDon&informaDonhidingEncapsulaDon:combinaDonofprocess&data

InformaDonhiding:funcDonalityishidden

aStudent:Student


AddSItocourselist




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InheritanceGeneralclassesarecreated(superclasses)Subclassescaninheritdataandmethodsfromasuperclass

Person

StudentTeacher

Regular Erasmus




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Polymorphism&dynamicbindingPolymorphism:thesamemessagecanhavedifferentmeanings

Dynamicbinding:typeofobjectisnotdeterminedunDlrun‐Dme

ContrastwithstaDcbinding

AddSItocourselist

Teacher

Student


Object‐OrientedSystemsAnalysis&Design


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A`emptstobalancedataandprocess

UDlizestheUnifiedModelingLanguage(UML)

CharacterisDcsofOOAD:Use‐caseDriven

ArchitectureCentricIteraDveandIncremental




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Usecases:describehowusersinteractwiththesystemtoperformsome

acDvity(placinganorder,makingareservaDon,…)

Use‐casedrivenUse‐casesdefinethebehaviorofasystem

Eachuse‐casefocusesononebusinessprocess(simplicity)




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Architecturecentric

FuncDonal(external)view:focusesontheuser’sperspecDve

StaDc(structural)view:focusesona`ributes,methods,classes&relaDonships

Dynamic(behavioral)view:focusesonmessagesbetweenclassesandresulDngbehaviors




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IteraDve&incremental

UndergoesconDnuoustesDng&refinement

Theanalystunderstandsthesystembe`eroverDme

EachiteraDonbringsthesystemclosertorealuserneeds


BenefitsofObject‐OrientedSystemsAnalysis&Design


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Breakacomplexsystemintosmaller,moremanageablemodules

WorkonmodulesindividuallyandeasilypiecethemodulesbacktogethertofromandIS

SeethesystemmorerealisDcally—astheusersdo

JoãoPauloFernandes,[email protected],[email protected]ãoPauloFernandes,[email protected]

UNIVERSIDADEDABEIRAINTERIORFaculdadedeEngenhariaDepartamentodeInformáDca

Concept Supports Leadsto

Classes,objects,methodsandmessages

‐ AmorerealisDcwayforpeopletothinkabouttheirbusiness‐ Highlycohesiveunitsthatcontainbothdataandprocesses

‐ BeèrcomunicaDonbetweenuserandanalyst‐ Reusableobjects

EncapsulaDonandinformaDonhiding

Looselycoupledunits ‐ Reusableobjects‐ Fewerrippleeffectsfromchangeswithinanobjectorthesystemitself

Inheritance Allowsustouseclassesandstandardtemplatesfromwhichotherclassescanbuild

‐ Lessredundancy‐ FastercreaDonofnewclasses‐ Standardsandconsistencywithinandacrossdevelopmentefforts

PolymorphismandDynamicBinding

Minimalmessagingthatisinterpretedbyobjectsthemselves

‐Simplerprogrammingofevents‐Easeinreplacingorchangingobjectsinasystem‐Fewerrippleeffectsfromchangeswithinanobjectorthesystemitself

Use‐casedrivenandusecases

AllowsusersandanalyststofocusonhowauserwillinteractwiththesystemtoperformasingleacDvity

‐Beèrunderstandingandgatheringofuserneeds‐BeèrcomunicaDonbetweenuserandanalyst

ArchitecturecentricandfuncDonal,staDc,anddynamicviews

ViewingtheevolvingsystemfrommulDplepointsofview

‐Beèrunderstandingandmodelingofuserneeds‐MorecompletedepicDonofinformaDonsystem

IteraDveand ConDnuoustesDngandrefinementof ‐MeeDngrealneedsofusers

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Object‐OrientedSystemsAnalysis&DesignwithUML


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UMLprovidesacommonvocabularyofobject‐orientedtermsanddiagrammingtechniquesrich

enoughtomodelanysystemsdevelopmentprojectfromanalysisthroughimplementaDon

Version2.0has14diagramsin2majorgroups:– Structurediagrams– Behaviordiagrams




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UMLstructurediagrams

RepresentthedataandstaDcrelaDonshipsinaninformaDonsystem

ClassObjectPackageDeploymentComponentCompositestructure




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UMLBehaviorDiagrams

DepictthedynamicrelaDonshipsamongtheinstancesorobjectsthatrepresentthebusinessinformaDonsystem

AcDvity

Sequence

CommunicaDon

InteracDonoverview

Timing

Behaviorstatemachine

Protocolstatemachine

Use‐casediagrams


Diagramname Usedto PrimaryPhase

StructureDiagrams

Class IllustratetherelaDonshipsbetweenthemodeledclasses Analysis,Design

Object IllustratetherelaDonshipsbetweenthemodeledobjects.Usedwhenactualinstancesofclasseswillbe`ercommunicatethemodel.

Analysis,Design

Package GroupotherUMLelementstoformhigherlevelconstructs Analysis,Design,ImplementaDon

Deployment Showthephysicalarchitectureofthesystem PhysicalDesign,ImplementaDon

Component IllustratethephysicalrelaDonshipsamongtheswcomponents PhysicalDesign,ImplementaDon

CompositeStructure Illustratetheinternalstructureofaclass Analysis,Design

BehavioralDiagrams

AcDvity Illustratebusinessworkflowsindependentofclasses,theflowofacDviDesinausecase,ordetaileddesignofamethod

Analysis,Design

Sequence Modelthebehaviorofobjectswithinausecase.Time‐based Analysis,Design

CommunicaDon Modelthebehaviorofobjectswithinausecase.FocusesonthecommunicaDonamongasetofcollaboraDngobjectsofanacDvity

Analysis,Design

InteracDonoverview Illustrateanoverviewoftheflowofcontrolofaprocess Analysis,Design

Timing IllustratetheinteracDonthattakesplaceamongasetofobjectsandthestatechangesinwhichtheygoalongaDmeaxis

Analysis,Design

BehavioralSM Examinethebehaviorofoneclass Analysis,Design

ProtocolSM Illustratethedependenciesamingthedifferentinterfacesofaclass Analysis,Design

Use‐Case CapturebusinessrequirementsforasystemandtoillustratetheinteracDonbetweenthesystemanditsenvironment

Analysis


Summary


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Object‐orientedsystemsdifferfromtradiDonalsystems

Object‐OrientedSystemsAnalysisandDesignusesause‐case‐driven, architecture‐centric, iteraDve, andincrementalinformaDonsystemsdevelopmentapproach

TheUnifiedModeling Language, orUML, is a standardset of diagramming techniques that can be used tosupportOOSAD

análise de sistemas (as) - departamento de informáticangarcia/aulas/asi1213/ubi asi 1213 aula...

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