Software Process & Agile Software Development

Transcription

1 CSE516 Science for Society Software Process & Agie Software Deveopment Apri 25, 2014 Ichu Yoon

2 Software A textbook description Instructions (computer programs) that when executed provide desired features, function, and performance; Data structures that enabe the programs to adequatey manipuate information and Documentation that describes the operation and use of the programs. Differences to hardware? Deveoped or Crafted No wear-out Custom-buit, amost aways 2

3 Software Engineering Fritz Bauer (1969) The estabishment and use of sound engineering principes in order to obtain economicay software that is reiabe and works efficienty on rea machines. The IEEE definition (1993) (1) The appication of a systematic, discipined, quantifiabe approach to the deveopment, operation, and maintenance of software; that is, the appication of engineering to software. (2) The study of approaches as in (1). 3

4 Software Engineering Layers toos methods process mode a quaity focus 4

5 Software Process? Communication Depoyment Modeing Panning Construction 5

6 Software Myths Beief ooks reasonabe in software deveopment, but miseading stakehoders Exampes Management Got behind schedue. Let s add more programmers and catch up. Outsource to a third party and reax. Customer Statement of objectives is sufficient to start writing programs. Software is fexibe so can be easiy changed ater. Practitioner Once competed writing a working program, the work is done. Unti program works, we cannot assess its quaity. Appying software engineering wi make the entire process sow. 6

7 Software Process A coection of work activities, actions, and tasks reevant to software deveopment Framework activities + Umbrea activities Process fow Linear Iterative Evoutionary Parae 7

8 Prescriptive Modes Prescriptive process modes advocate an ordery approach to software engineering That eads to a few questions If prescriptive process modes strive for structure and order, are they inappropriate for a software word that thrives on change? Yet, if we reject traditiona process modes (and the order they impy) and repace them with something ess structured, do we make it impossibe to achieve coordination and coherence in software work? 8

9 The Waterfa Mode Cassic Sti in use for miitary domains Probems? Deveopment is not-reay sequentia. Uncear requirements at the beginning Customers shoud wait under code generation. 9

10 Incrementa Process Mode Produce deiverabe increments in each iteration First increments is often core product Get customer feedback Usefu when Staffing probem exists 10

11 Evoutionary Process Mode Prototyping Quick design Mainy for requirements eicitation Probems? Tempted to keep it. Feedback Miestones Spira Mode Risk-driven deveopment Anchor point miestones Teams define spira objectives Adjustabe for maintenance Reaistic for arge-scae project 11 Risk anaysis

12 Concurrent Modes State transition mode for process eements can be defined for activities, actions, or tasks. 12

13 The Unified Process (UP) A use-case driven, architecture-centric, iterative and incrementa software process cosey aigned with the Unified Modeing Language (UML) Sometimes, caed Rationa Unified Process (RUP) after the Rationa Corporation Discussion started from UML Combined best features of object-oriented anaysis and design methods De facto industry standard for OOSD However, acks of process framework to guide teams to pay with UML 13

14 UP Phases Inception Requirement gathering Rough architecture Define initia use cases Eaboration Refine use cases, expand architecture Construction Make use cases operationa for end users Unit & integration test based on use cases Transition Beta-testing and feedback coection, support doc. creation Production Monitoring and maintenance 14

15 UP Phases and Typica Work Amount Phases workfows (tasks) iterations #1 # #n

16 Manifesto for Agie Software Deveopment 16

17 What is Agiity? Agie: readiness for motion, nimbeness, activity, dexterity in motion Agiity The abiity to both create and respond to change in order to profit in a turbuent business environment Chaordic Companies need to determine the amount of agiity they need to be competitive Exhibiting properties of both chaos and order The bend of chaos and order inherent in the externa environment and in peope themseves, argues against the prevaiing wisdom about predictabiity and panning Things get done because peope adapt, not because they savishy foow processes 17

18 Agiity and the Cost of Change 18

19 Agiity Principes Highest priority on customer satisfaction Admit requirements changes, even ate in deveopment Deiver working software frequenty a coupe of weeks or a coupe of months prefer shorter scae Measure of progress Work together with customers throughout the project Trust individuas and sef-organizing teams Constant face to face conversation Attention to technica exceence and good design Simpe architecture Tune 19

20 Human Factors Anyway. Human deveops software. Key traits required for the agie team and members: Competence taent, skis, and knowedge Common focus goa-driven Coaboration for task execution Decision-making abiity autonomy Fuzzy probem-soving abiity wecoming changes Mutua trust and respect Sef-organization 20

21 An Agie Process Customer-driven (scenarios, user stories, feedback, test) Sequence of short iterations Iterative and deiver mutipe software increments Put emphasis on construction activities XP Scrum 21

22 Extreme Programming (XP) The most widey used agie process, originay proposed by Kent Beck Vaues Communication informa face-to-face Simpicity design for today, but in an efficient way Feedback from software, customer, team members Courage at changes Respect between a stakehoders and team members Context Prefer Object-Oriented deveopment paradigm Consist of practices in four framework activities 22

23 Extreme Programming (XP) XP Panning (or panning game) Start with user stories (istening, use of index cards) Story assessment and cost assignment Story grouping for a deiverabe increment Make commitment on deivery date Use project veocity, after the first increment. Consider: Number of stories impemented Cost assigned Usefu for estimating subsequent deivery dates for other increments Usefu for determining over-commitment for stories (may adjust) 23

24 Extreme Programming (XP) XP Design Foows the KIS (Keep It Simpe) principe Encourage the use of CRC cards Cass, Responsibiity, and Coaborator For difficut design probems, create spike soutions Design prototype (risk management) Encourages merciess refactoring an iterative refinement of the interna program design Design optimization Design artifacts are minima and considered transient 24

25 Extreme Programming (XP) CRC card exampes 25

26 Extreme Programming (XP) XP Coding Recommends the construction of a unit test for a story before coding commences Encourages pair programming Continuousy integrate with other work and run smoke testing XP Testing A unit tests are executed daiy Heps regression testing at code modification Combined into universa testing suite Acceptance tests (customer test) Focus on overa (visibe and reviewabe) features and functionaity 26

27 Extreme Programming (XP) user st ories vaues accept ance t est crit eria it erat ion pan simpe design CRC cards spike sout ions prot ot ypes refact oring pair programming Reease software increment project veocity computed unit t est cont inuous int egrat ion accept ance t est ing 27

28 Extreme Programming (XP) 28

29 Scrum Originay proposed by Schwaber and Beede [2001] Scrum - distinguishing features Partition deveopment work into packets On-going testing and documentation during construction Start with user stories (caed backogs) Reease in sprints derived from backogs Very short meetings (even without chairs) and timeboxing 29

30 After 10 years after Agie Manifesto The agie movement is in some ways a bit ike a teenager: very sef-conscious, checking constanty its appearance in a mirror, accepting few criticisms, ony interested in being with its peers, rejecting en boc a wisdom from the past, just because it is from the past, adopting fads and new jargon, at times cocky and arrogant. But I have no doubts that it wi mature further, become more open to the outside word, more refective, and aso therefore more effective. - Phiippe Kruchten 30