1. 29 September 2014

2. Interactions  There is no “right answer”  Typically people and product are fixed  … can adapt process  (which is where we will start)

4. Fundamental Steps  Requirements  Design  Implementation  Test  Deployment  Maintenance

5. Processes  Differ by how often you do the steps Focus and emphasis  Points on the spectrum  Differences in overhead  Three fundamental processes Waterfall Spiral Iterative

7. Waterfall Do it once Traditional model Used for large next version releases, especially when well understood product tightly coupled changes

8. Waterfall 1970s Built on 1950’s stage-wise process Recognized the need for feedback Limited Heavy process

9. Waterfall  Pros Simple documentation management Clean design phase  Cons Least flexibility No early feedback

11. Iterative (a.k.a. Agile) Many iterations Each iteration is on a fixed cycle Typically biweekly Used for projects with lots of small independent, but well understood, changes small development team strong client involvement

12. Iterative Reaction to waterfall Derived from “evolutionary” process Requirements and specs evolve over time Two well-known models Extreme programming SCRUM

13. Iterative (a.k.a. Agile)  Pros Fast feedback on problems Very adaptable to any changes Lots of versions to work with Heavy user involvement  Cons Document maintenance Code maintenance Requires good automation

15. Spiral Few iterations Each iteration adds new requirements Used often for projects with less well defined requirements

16. Spiral Risk based Barry Boehm 1988 “A Spiral Model of Software Development and Enhancement”

17. Spiral  Pros Adaptation to changes based on risks Good customer interaction Early version Limited iterations provide phase structure  Cons Document maintenance

19. Unified Process (hybrid)  Spiral within waterfall  Recognizes iterations differ  Also known as Rational Unified Process (Rational products) Rational Unified Process Phases Core Processes

20. Phases and Milestones Phase  Inception  Elaboration  Construction  Transition Milestone  Objectives  Architecture  Initial Operational Capability  Product Release

21. Iterations in Phases  Phase broken down into iterations  Iteration: Complete development loop Resulting in a release

22. Best on Best Practices 1. Develop software iteratively 2. Manage requirements 3. Use component-based architectures 4. Visually model software 5. Verify software quality 6. Control changes to software

24. Cleanroom Development  Different from clean room design  Harlan Mills, late 80s  Principles Software development based on formal methods: formal proofs and validations instead of unit tests Incremental implementation under statistical quality control Statistically sound testing: most likely inputs

25. Process From Ian Sommerville (2008)

26. Strategies  Formal specification  Incremental development  Structured programming  Static verification  Statistical testing of the system

28. Historically  Waterfall: 1970, built on 1950’s stage-wise processes Recognized need for feedback  Iterative (agile): late 70s,modeled on evolutionary model Didn’t work well for large products  Spiral: 1988, risk-based

29. Reality  Most development is toward the agile side  But, how fast, how formal differs considerably by … Industry Organization Project