5.2Software Development Management

The best approach for building a system varies with how likely requirements are to change and how frequently releases are demanded. The goal here is to master how to choose a development model, DevOps and CI/CD for automating and accelerating development and release, and techniques for estimating scale numerically, so you can make situational judgments.

5.2.1Development model characteristics and selection criteria

• The waterfall model is the traditional model that proceeds through requirements definition, design, implementation, and testing in sequence, on the assumption that there is no going back. Each stage produces a clear deliverable, making it well suited to progress management on large projects, but it is poorly suited to projects where requirements are hard to fix mid-development (the later a requirement change happens, the larger the rework).
• Agile development is the umbrella term for development approaches that prioritize rapid response to changing requirements, incrementally building working software through repeated short periods (iterations/sprints). Scrum is one of the representative agile frameworks, in which work items are selected each sprint (a short, fixed period) from a priority-ordered product backlog. XP (Extreme Programming) is an agile method that emphasizes practices such as pair programming, test-driven development (TDD), and refactoring.
• Selection criteria: waterfall suits projects where requirements are clear, change is minimal, and large-scale, rigorous progress management is needed, while agile suits projects where requirements are likely to change and early user feedback needs to be incorporated. The key understanding is that the two are not a matter of superiority but of different applicable conditions.