需求分析和系统设计摘要ppt培训课件

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1、TopicsThenatureofsoftwaredevelopmentSystemplanningSystemsforthreemanagementlevelsSoftwaredevelopmentlifecycleTheessenceofsoftwaredevelopmentOnlyoneoutofthreesoftwareprojectscompleteon-timeandon-budget(TheStandishGroupreport,2003)Theessenceofsoftwaredevelopment:d

2、efinedbytheissuesinherentinthesoftwareitself-softwareisaproductofacreativeact(notaresultofarepetitiveactofmanufacturing)difficultiesnotamenabletobreakthroughsor‘silverbullets’-definesoftwaredevelopmentinvariantsconsequenceoftheinherentsoftwarecomplexity,complexi

3、ty,conformity,conformity,changeability,andchangeability,andinvisibilityTheaccidentsofsoftwaredevelopment‘Accidentaldifficulties’duetosoftwareproductionpractices-amenabletohumaninterventionattributedmostlytothefactthataninformationsystemisasocialsystemmustnotbead

4、dingtothecomplexityandtothepotentiallackofsupportabilityofthesoftwareproductsupportability=understandability+maintainability+scalability(extensibility)Relatedto:StakeholdersProcessModelinglanguageandtoolsWillbediscussedsoonSoftwaredevelopmentinvariantsSoftwarein

5、inherentlycomplex•functionofinterdependenciesbetweencomponentsofwhichthesoftwareproductiscomposedÆcomplexityinthewires•Dataintensiveapplications(enterpriseinformationsystems)areparticularlycomplexSoftwaremustconformto:•hardware/softwareplatformonwhichitisbuilt•p

6、re-existinginformationsystemsSoftwaremustbebuilttoaccommodatechangeSoftwareisburieddeeplyin“invisible”programmingstatements,binarylibrarycode,andsurroundingsystemsoftwareStakeholdersPeoplewhohaveastakeinasoftwareproject:Customers(usersandsystemowners)Developers(

7、analysts,designers,programmers,etc.)Informationsystemsaresocialsystems-developedbypeople(developers)forpeople(customers)Themaincausesofsoftwarefailurecanbetracedtothestakeholderfactoronthecustomerend,andonthedeveloperendSoftwareprocessDefinesactivitiesandorganiz

8、ationalproceduresusedinsoftwareproductionandmaintenanceAprocessmodel:statesanorderforcarryingoutactivities;specifieswhatdevelopmentartifactsaretobedeliveredandwhen;as