Agile Software Development

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Agile Software Development
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Traditional Software Development

• Initiation (RFP)
• Feasibility study
• Technical can we build it?
• Economic should we build it?
• Operational if we build it, will it be used?
• Schedule will it be ready in time?
• Requirements definition
• Specifications
• Project plan

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Traditional Software Development

• 6. Logical design (external view)
• 7. Physical design (internal view)
• 8. Coding (or code acquisition)
• Testing
• Maintenance
• SDLC Investigate, Analyze, Design, Implement
  and Maintain

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Plan Driven Approach

• Roots may be traced to engineering concepts
• Standards and well-defined processes process
  discipline
• Adherence to processes
• Completeness of documentation
• Traceability across requirements, design, and
  code is mandatory

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Plan driven Approach

• Processes are defined, standardized, and
  incrementally improved
• Standardization allows for comparisons and
  repeatability
• Training, getting information, and estimating are
  supposedly easier
• Less need for retraining
• People can be replaced! Loss of key personnel
  does not doom a project!

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Advantages

• Easy to understand, easy to use
• Provides structure to inexperienced staff
• Milestones are well understood
• Sets requirements stability
• Good for management control (plan, staff, track)
• Aim for predictability and stability
• Plan extensively at the outset to anticipate
  changes/variations
• They try to tame change
• Emphasis on quality of software and
  predictability
• Exemplified by the Capability Maturity Model

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Capability Maturity Model

• A bench-mark for measuring the maturity of an
  organizations software process
• CMM defines 5 levels of process maturity based on
  certain Key Process Areas (KPA)
• SEI rates organization on their maturity levels.

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Capability Maturity Model
Level Focus Key Process Area
5 Optimizing (1) Continual process improvement Defect Prevention, Technology Change Management, Process Change Management
4 Managed (5) Product and process quality Quantitative process and software quality management
3 Defined (10) Engineering processes and organizational support Organizational process focus, organizational process definition, training program, integrated software management, software product engineering, inter-group coordination, peer reviews
2 Repeatable (15) Project management processes Requirements management, software project planning, sw project tracking oversight, sw subcontract management,
1 Initial (a little less than 70) Competent people heroics - ad hoc Competent people heroics - ad hoc
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Disadvantages

• However
• All requirements must be known upfront
• Deliverables created for each phase are
  considered frozen inhibits flexibility
• Can give a false impression of progress
• Does not reflect problem-solving nature of
  software development iterations of phases
• Integration is one big bang at the end
• Little opportunity for customer to preview the
  system (until it may be too late)

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Challenges

• Standish Group gt 50 of software projects fail
  to meet their productivity, cost or functionality
  goals
• Changing requirements (25?)
• User involvement (13?)
• Executive Support (7.5?)
• Lack of skills/technical incompetence (7)
• Lack of resources (6.4)
• Unrealistic expectations (6?)
• Unclear objectives (5.3)
• Unrealistic deadlines/time-frames (4.3)

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Discipline vs Agility

• Discipline creates well-organized memories,
  history, and experience
• Agility makes use of memory and history to adapt,
  react, and to be opportunistic
• What do you think is more important? Why?

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Agile Manifesto

• Value
• Individuals and their interactions over processes
  and tools
• Working software over comprehensive documentation
• Customer collaboration over contract negotiation
• Responding to change over following a plan

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Agile Methods

• Agile software development is a conceptual
  framework for undertaking software engineering
  projects.
• Most agile methods attempt to minimize risk by
  developing software in short timeboxes, called
  iterations, which may typically last one to four
  weeks.
• Each iteration is like a miniature software
  project of its own, and includes all of the tasks
  necessary to release the mini-increment of new
  functionality.
• Agile methods emphasize realtime communication,
  preferably face-to-face, over written documents.
• Agile methods rely on the close collaboration of
  activity engaged individuals with ordinary
  talents and has the ability to flexibly schedule
  the implementation of functionality, responding
  to changing business needs.

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Examples

• Extreme Programming ( X P)
• Adaptive Software Development
• Crystal
• Scrum
• Feature-Driven Development

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Extreme programming Practices

1. Planning game determine scope of the next
   release by combining business priorities and
   technical estimates
2. Small releases put a simple system into
   production, then release new versions in very
   short cycle
3. Metaphor all development is guided by a simple
   shared story of how the whole system works
4. Simple design system is designed as simply as
   possible (extra complexity removed as soon as
   found)
5. Testing programmers continuously write unit
   tests customers write tests for features
6. Refactoring programmers continuously
   restructure the system without changing its
   behavior to remove duplication and simplify

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Extreme programming Practices

• Pair-programming -- all production code is
  written with two programmers at one machine
• Collective ownership anyone can change any code
  anywhere in the system at any time.
• Continuous integration integrate and build the
  system many times a day every time a task is
  completed.
• 40-hour week work no more than 40 hours a week
  as a rule
• On-site customer a user is on the team and
  available full-time to answer questions
• Coding standards programmers write all code in
  accordance with rules emphasizing communication
  through the code