Agile Development

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Agile Development
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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

Kent Beck et al
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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

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An Agile Process

• Is driven by customer descriptions of what is
  required (scenarios)
• Recognizes that plans are short-lived
• Develops software iteratively with a heavy
  emphasis on construction activities
• Delivers multiple software increments
• Adapts as changes occur

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Agile Process Models

• Extreme Programming (XP)
• Adaptive Software Development (ASD)
• Dynamic Systems Development Method (DSDM)
• Scrum
• Crystal
• Feature Driven Development (FDD)
• Agile Modeling (AM)

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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

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Extreme Programming (XP)

• Key activities
• Planning (user stories created and ordered by
  customer value)
• Design (simple designs preferred,
  Class-Responsibility Collaboration (CRC) cards
  and design prototypes are only work products,
  encourages use of refactoring)

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Extreme Programming (XP)

• Key activities
• Coding (focuses on unit tests to exercise
  stories, emphasizes use of pairs programming to
  create story code, continuous integration and
  smoke testing is utilized)
• Testing (unit tests created before coding are
  implemented, integration and validation testing
  done on daily basis, acceptance tests focus on
  system features and functions viewable by the
  customer)

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Extreme Programming (XP)
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Adaptive Software Development

• Self-organization arises when independent agents
  cooperate to create a solution to a problem that
  is beyond the capability of any individual agent
• Emphasizes self-organizing teams, interpersonal
  collaboration, and both individual and team
  learning
• Adaptive cycle characteristics

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Adaptive Software Development

• 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

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Adaptive Software Development
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Dynamic Systems Development Method

• DSDM guiding principles
• Active user involvement is imperative.
• DSDM teams must be empowered to make decisions.
• The focus is on frequent delivery of products.
• Fitness for business purpose is the essential
  criterion for acceptance of deliverables.

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Dynamic Systems Development Method

• DSDM guiding principles
• Iterative and incremental development is
  necessary to converge on an accurate business
  solution.
• All changes during development are reversible.
• Requirements are baselined at a high level
• Testing is integrated throughout the life-cycle.

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Dynamic Systems Development Method

• Provides a framework for building and maintaining
  systems which meet tight time constraints using
  incremental prototyping in a controlled
  environment
• Each increment only delivers enough functionality
  to move to the next increment
• Uses time boxes to fix time and resources to
  determine how much functionality will be
  delivered in each increment

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Dynamic Systems Development Method

• DSDM Life cycle activities
• Feasibility study (establishes requirements and
  constraints)
• Business study (establishes functional and
  information requirements needed to provide
  business value)
• Functional model iteration (produces set of
  incremental prototypes to demonstrate
  functionality to customer)
• Design and build iteration (revisits prototypes
  to ensure they provide business value for end
  users, may occur concurrently with functional
  model iteration)
• Implementation (latest iteration placed in
  operational environment)

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Scrum

• Scrum principles
• Small working team used to maximize
  communication, minimize overhead, and maximize
  sharing of informal knowledge
• Process must be adaptable to both technical and
  business challenges
• Process yields frequent increments that can be
  inspected, adjusted, tested, documented and built
  on
• Development work and people performing it are
  partitioned into clean, low coupling partitions
• Testing and documentation is performed as the
  product is built

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Scrum

• Process patterns defining development activities
• Backlog prioritized list of requirements or
  features, items can be added at any time
• Sprints work units required to achieve one of
  the backlog items, must fit into a predefined
  time-box
• Scrum meetings (15 minute daily meetings)
  addressing these questions What was done since
  last meeting? What obstacles were encountered?
  What will be done by the next meeting?
• Demos deliver software increment to customer for
  evaluation

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Crystal

• Development approach that puts a premium on
  maneuverability during a resource-limited game
• Incremental development strategy used with 1 to 3
  month time lines
• Reflection workshops conducted before project
  begins, during increment development activity,
  and after increment is delivered

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Crystal

• Crystal principles
• Its always cheaper and faster to communicate
  face-to-face
• As methodologies become more formal teams become
  weighed down and have trouble adapting to project
  work vagaries
• As projects grow in size, teams become larger and
  methodologies become heavier
• As projects grow in criticality some degree of
  formality will need to be introduced in parts of
  the methodology

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Crystal

• Crystal principles
• As feedback and communication become more
  efficient the need for intermediate work products
  is reduced
• Discipline, skills, and understanding counter
  process, formality, and documentation
• Team members not on the critical project path can
  spend their excess time improving the product or
  helping people who are on the critical path

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Feature Driven Development

• Practical process model for object-oriented
  software engineering
• Feature is a client-valued function, can be
  implemented in two weeks or less

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Feature Driven Development

• FDD Philosophy
• Emphasizes collaboration among team members
• Manages problem and project complexity using
  feature-based decomposition followed integration
  of software increments
• Technical communication using verbal, graphical,
  and textual means
• Software quality encouraged by using incremental
  development, design and code inspections, SQA
  audits, metric collection, and use of patterns

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Feature Driven Development

• Framework activities
• Develop overall model contains set of classes
  depicting business model of application to be
  built
• Build features list features extracted from
  domain model and are categorized and prioritized,
  work is broken up into two week chunks
• Plan by feature features assessed based on
  priority, effort, technical issues, schedule
  dependencies

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Feature Driven Development

• Framework activities
• Design by feature classes relevant to feature
  are chosen, class and method prologs are written,
  preliminary design detail developed, owner
  assigned to each class, owner responsible for
  maintaining design document for his or her own
  work packages
• Build by feature class owner translates design
  into source code and performs unit testing,
  integration performed by chief programmer

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Feature Driven Development

• Emphasis is on defining features
• A features list is created and plan by feature
  is conducted
• Design and construction merge in FDD
• Six milestones during the design and
  implementation of a feature design walkthrough,
  design, design inspection, code, code generation,
  promote to build
• Uses a feature template
• ltactiongt the ltresultgt ltby for of togt a(n)
  ltobjectgt

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Agile Modeling

• Practice-based methodology for effective
  modeling and documentation of software systems in
  a light-weight manner
• Requirements gathering and analysis modeling
• Work collaboratively to find out what customer
  wants to do
• Once requirements model is built collaborative
  analysis modeling continues with the customer

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Agile Modeling

• Modeling principles
• Model with a purpose
• Use multiple models
• Travel light (only keep models with long-term
  value)
• Content is more important than representation
• Know the models and tools you use to create them
• Adapt locally

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Agile Modeling

• Architectural modeling
• Derives preliminary architecture from analysis
  model
• Architectural model must be realistic for the
  environment and must be understandable by
  developers