Why software development difficult/different MIS, lack of visualization: moving targets, between se. communications, specification: ph1 report Design: 2 levels: Architecture/high-level: modules/classes and detail/low-level design: alg+data struct (=program) modules + comm; ds + logic/alg: each module alg, math: difference equation: discrete version of differential eq/ math/modeling Coding/implementation phase: understandable, clean logic, swimming and integration: deliver prod Testing + integration Maintenance: customer SQA: system quality assurance team Toyota () Sys an>plan>design…. pros and cons: quality, documentation, strict discipline; SQA Cons: time/$ consuming; lack of comm; big overall risk; miss target

Software quality: most important: meet spec; other general ones: user friendly, efficiency, robustness, reliability, support Rapid prototyping: quickly build summarizations reflect main func in order to communicate with clients/peers embedded in wf model pros: better comm; better response/feedback cons: invite more moving targets, Wf+rp Evolution: simplecomplex: system having ind. components partition system into many builds: Ccny mis: std + fac + lib + funding 2yrs std(water fall+ proto): 8 months stop reduce risk Pros: reduce overall risk, Cons: fatal blow—hard to integrate, have to redo design/coding Spiral model: military huge system water fall + risk analysis at the end of each phase, Bayesian reasoning example Pros: safety ; cons: very expensive Pros and cons of these models