Modularity

Kind: principle

Layer: Structural Core

Record: architecture:modularity

Severity: mandatory

Scope: package, component, service, system

Canonical: Ontology

A design rule that a system is divided into cohesive modules with explicit boundaries and few dependencies between them.

Listed in Architecture principles, after Abstraction and before Composability.

Requires

• High Cohesion
• Low Coupling
• Explicit Boundaries

Reinforces

• Separation of Concerns
• Composability

Enables

• Replaceability
• Plugin Architecture

Conflicts with

• Big Ball of Mud

In tension with

• Cross-Cutting Concerns

Tensions

• Modularity / Cross-Cutting Concerns

Violated by

• Circular Dependency
• Shared Mutable State
• Boundary Leakage

Refactored by

• Split Module
• Define Module Boundaries
• Invert Dependency

Severity

• mandatory

Category

• Core Modular Design

Reinforced by

• Bounded Context
• Single Responsibility Principle
• Component-Based Architecture
• Package by Feature

Linked from

• A system is a graph
• Principles are typed
• Anti-patterns
• Domain Architecture
• Core Modular Design
• Plugin / Extensibility / IoC
• Codebase / System Architecture Styles
• Core Modular Design
• Core Vocabulary
• SOLID / Object-Oriented Design
• Severity levels
• The resolutions