Today's Models

There are a few more major SDLC methodologies, but I didn't feel they were as applicable to us as the five others being covered today.

Other examples:

• Continuous Integration
• Rapid Application Development
• Shape Up
• Behavior-Driven Development
• Chaos Model
• And more...

Disclaimer

Waterfall/
Cascade/
Traditional

Each phase must be completed before the next phase can begin and there is no overlapping in phases

• Requirements up front saves time later
• More focus on prep and documentation
• Well-defined milestones/goals

Pros

• Requires well-defined goals at the start
• Changing requirements means starting over
• Less flexible to change

Cons

Iterative

More than one iteration may be

in progress at the same time

• Don't need complete requirements to start
• Can get feedback after each iteration
• Can deliver before all features are implemented

Pros

• Architecture problems with adding features
• Can have too much focus on an iteration and not the big picture
• Difficult to estimate new feature timelines

Cons

Prototyping

Creating incomplete software as a proof of concept.

• Sooner user feedback
• Discover difficult parts sooner
• Provides a reference for future development

Pros

• Usually poor requirements and impractical solution
• Possible overuse of prototype code
• Time invested in prototype IS NOT design time

Cons

Spiral

Combination of iterative and waterfall with emphasis on "risk analysis"

About "Risk"

The concept is:

"If [X] happens it will cost $[Y]"

• Changes may be added flexibly in later phases
• Balances risk vs time investment
• Good for medium to long term projects expecting many changes

Pros

• Continual refactoring can slow progress
• Milestone timelines are harder to estimate further along the spiral
• Can be indefinite for poorly defined projects

Cons

Short cycles, iterative and incremental delivery, failing fast, getting feedback, delivering value early.

Most current SDLC practices are Agile in some way.

• Work can begin with minimal requirements
• Separating out planners means more informed decisions
• Early feedback and testing means better product overall

Pros

• Some work is dropped if requirements change
• Many stakeholders leads to scope creep
• Short iterations can lead to worse documentation

Cons