An Agile Methodology
Prescriptive software methodologies typically employ
sequential, step-wise wise models consisting of requirements analysis, design,
implementation, and integration testing.
Figure 1
Historically, this approach does not react well to changing
requirements, is difficult to estimate for time and cost, and is
architecturally fragile.
Agile methodologies provide a collection of foundational
values, guiding principles and development practices that to address the
challenges of prescriptive, weighty methodologies to produce software in a lighter, faster, more
people-centric manner. Agile
methodologies work best with motivated, reliable people who desire to work
together to fulfill their stakeholder's business goals. Slackers, complainers, and lazy developers
need not apply!
Figure 2
Agile developers have as their foundation the following values:
- Individuals and interactions over processes and tools
- Working software over comprehensive documentation
- Customer collaboration over contract negotiation
- Responding to change over following a plan
Guiding principles
emerge from the foundational values:
- Software is the primary goal.
The developer's highest priority is
to satisfy the customer through early and continuous delivery of quality
software.
- Embrace change
Changing requirements are expected
and embraced throughout the software lifecycle.
- Frequent delivery
Software is delivered at frequent
intervals with a preference for shorter timescales.
- Encourage collaboration and promote communication
Developers and Stakeholders should
collaborate throughout the software lifecycle.
The most efficient and effective method of communication is face-to-face
conversation. Immediate feedback is desirable and preferred.
- Trust is essential
The best architectures,
requirements, and designs emerge from self-organizing teams. Equip the developers with the tools and
environment to be successful and trust them to get the job done. Allow the team to self-organize based on its
strengths and weaknesses to accomplish the work.
- Be proactive
As the project grows in size and
complexity, proactively seek principles and practices that increase efficiency
so the team can continue at the same development pace while maintaining quality
and sanity.
- Strive for quality work
Continuous attention to technical
excellence and good design enhances quality.
- Keep it simple
Suspect complicated solutions
without justification. Maximizing the amount of work not done is essential.
- Introspection is vital
At regular intervals, the team
determines the strategies and practices that worked and those that did not.
Reflect on way to become more effective and tune and adjust the team’s strategy
and practices.
The Guiding
Principles drive development practices:
- Active stakeholder participation
Collaborate with the stakeholder
who has the authority and ability to provide information relevant to the system
under construction and to make pertinent and timely decisions regarding it.
- Agile Modeling
Communicates and
establishes the “good enough” solution model.
- Simple design
Resist the desire to complicate and
code for the future – keep design and development simple.
- Standards
Consistent design and coding
standards resolve ambiguity and increase communication.
- Small releases
Partitioning a large effort into
small, incremental releases delivers working software to stakeholders faster
and reacts quicker to changing requirements.
- Pair programming
Two heads are often better than
one!
- Iterative, incremental development
Partition the
solution into units that can be completed and tested within a series of
development cycles.
- Test Driven development
Defines the
requirements of the code and fosters refactoring.
- Refactoring
Improves the
structure and clarity of the code without changing the functionality.
- Continuous integration
Identifies integration errors
faster.
- Position for next project
Use the artifacts and successful practices from
one project to inform and position the next project for success.
Agile methodologies vary by team and mature over time so
starting with a broad vision is helpful to transition from a prescriptive
methodology. The following is an agile
methodology that retains familiar procedural steps, but incorporates agile
principles and practices using four phases.
Figure 3
Phase 1: Domain Understanding (Conception)
a. Understand the
application from the perspective of the stakeholder
Time to accomplish:
normally accomplished in days; sometimes 1 week
Inputs: customer
collaboration, requirements documents, legacy code
Possible artifacts
that demonstrate understanding:
- High level problem statement
- Generalized use cases that captures the intentions of a user
- High level activity diagram
- High level work flow
Agile practices
employed:
- Active stakeholder participation
b. Estimate the solution to the problem
Time to accomplish:
Hours
Inputs: High level
use cases, project requirements
Artifacts: project estimate
Agile practices
employed:
- Active stakeholder participation
- Small releases
Phase 2 - Model the solution to the problem (Elaboration)
Time to accomplish:
Several days to 1 week for large problem domains
Inputs: High level
use cases, project requirements from Phase 1
Artifacts:
- Agile class diagrams depicting data layer objects
- Agile class diagrams depicting business layer objects
- Agile sequence diagrams for complex logic
- User interface mock-ups and flows
- Others as “painfully” required
Agile practices
employed:
- Active stakeholder participation
- Agile Modeling
- Style and modeling standards
- Simple design
- Model refactoring
Phase 3 - Implement the solution to the problem
(Construction)
Time to accomplish:
Weeks to months
Inputs: Design
Model from Phase 2
Artifacts: Working
code
Agile practices
employed:
- Active stakeholder participation
- Test Driven development
- Pair programming
- Accomplished in iterations
- Develop Incrementally
- Code refactoring
- Coding standards
Phase 4 - Verify the solution (Transition)
Time to accomplish: Hours to Days
Inputs: Implementation from Phase 3
Artifacts: Proven and tested code
Agile practices
employed:
- Active stakeholder participation
- Continuous Integration Testing; run the test suite at least daily, email the results to team
Additional References
The following references elaborate on the topic of Agile
Methodology and modeling.
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