Chapter 3.pdf Agile Development + framework
- 1. 1 Chapter 3 Agile Development
- 2. 2 The Manifesto for Agile Software Development “We are uncovering better ways of developing software by doing it and helping others do it. Through this work we have come to value: •Individuals and interactions over processes and tools •Working software over comprehensive documentation •Customer collaboration over contract negotiation •Responding to change over following a plan That is, while there is value in the items on the right, we value the items on the left more.” Kent Beck et al
- 3. 3 What is “Agility”? Effective (rapid and adaptive) response to change Effective communication among all stakeholders Drawing the customer onto the team Organizing a team so that it is in control of the work performed Yielding … Rapid, incremental delivery of software
- 4. 4 Agility and the Cost of Change
- 5. 5 Extreme Programming (XP) The most widely used agile process, originally proposed by Kent Beck XP Planning Begins with the creation of “user stories” Agile team assesses each story and assigns a cost Stories are grouped to for a deliverable increment A commitment is made on delivery date After the first increment “project velocity” is used to help define subsequent delivery dates for other increments
- 6. 6 Extreme Programming (XP) XP Design Follows the KIS principle Encourage the use of CRC cards (see Chapter 8) For difficult design problems, suggests the creation of “spike solutions”—a design prototype Encourages “refactoring”—an iterative refinement of the internal program design XP Coding Recommends the construction of a unit test for a store before coding commences Encourages “pair programming” XP Testing All unit tests are executed daily “Acceptance tests” are defined by the customer and excuted to assess customer visible functionality
- 7. 7 Extreme Programming (XP) unit t est cont inuous int egrat ion accept ance t est ing pair programming Release user st ories values accept ance t est crit eria it erat ion plan simple design CRC cards spike solut ions prot ot ypes refact oring software increment project velocity computed
- 8. 8 Adaptive Software Development Originally proposed by Jim Highsmith ASD — distinguishing features Mission-driven planning Component-based focus Uses “time-boxing” (See Chapter 24) Explicit consideration of risks Emphasizes collaboration for requirements gathering Emphasizes “learning” throughout the process
- 9. 9 Adaptive Software Development adapt ive cycle planning uses mission st at ement project const raint s basic requirement s t ime-boxed release plan Requirement s gat hering JAD mini-specs component s implement ed/ t est ed focus groups for feedback formal t echnical reviews post mort ems software increment adjustments for subsequent cycles Release
- 10. 10 Scrum Originally proposed by Schwaber and Beedle Scrum—distinguishing features Development work is partitioned into “packets” Testing and documentation are on-going as the product is constructed Work occurs in “sprints” and is derived from a “backlog” of existing requirements Meetings are very short and sometimes conducted without chairs “demos” are delivered to the customer with the time- box allocated
- 11. 11 Scrum Scrum Process Flow (used with permission)
- 12. 12 Crystal Proposed by Cockburn and Highsmith Crystal—distinguishing features Actually a family of process models that allow “maneuverability” based on problem characteristics Face-to-face communication is emphasized Suggests the use of “reflection workshops” to review the work habits of the team