What is functional decomposition (FDD)?

This is an iterative and incremental software development process that focuses on "features".

Key stages:

1. Developing the overall functionality model: Creating a high-level object model of the domain.
2. Building the feature list: Defining "features" (functionalities) to be implemented. Each feature is a small-granularity user functionality valuable to the client. The format of a feature is often "Action on the result, using an object".
3. Planning by functionality: Distributing features among iterations (sprints) and teams.
4. Designing by functionality: Designing each feature. Includes developing detailed diagrams and documentation.
5. Building by functionality: Implementation, testing, and integration of features.

Advantages of FDD:

• Progress visualization: Easily track the percentage of completed features.
• Early and frequent releases: Allows obtaining a working product at early stages.
• Focus on customer value: Development is oriented towards user needs.
• Risk reduction: Early detection of problems through frequent integration.

Disadvantages of FDD:

• Requires experienced architects: Creating the correct object model is critically important.
• Complexity for large projects: Managing a large number of small features can be challenging.
• Risk of requirements uncertainty: If requirements change frequently, it can disrupt the plan.

FDD works well with Agile approaches and is often used in projects with clearly defined business processes.