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Component

3 min readStatus:Seedling

Core Idea

A component is a modular, self-contained unit of software that represents the physical packaging of architectural building blocks.

Definition

A component is a modular, self-contained unit of software that represents the physical packaging of architectural building blocks. It delivers distinct functionality through well-defined interfaces and can be deployed independently within an execution environment. Components correspond to identifiable business functions (e.g., payment processing, user authentication) or infrastructure functions (e.g., logging, caching), serving as the fundamental building blocks that implement an architecture’s structure.

Key Characteristics

  • Physical manifestation: Components are the physical packaging for modules and subsystems, residing as deployable units in runtime environments (e.g., Java JARs, .NET assemblies, microservices)
  • Encapsulation with interfaces: Components expose clear communication interfaces containing methods, events, and properties while hiding internal implementation details
  • Independent deployability: Components can be deployed, replaced, or updated independently without requiring changes to the entire system
  • Architectural scope: Components capture the architectural view of software; they represent coarse-grained elements rather than fine-grained implementation details
  • Functional cohesion: Each component groups related responsibilities that serve a single business or infrastructure purpose, maintaining high internal cohesion
  • Reusability: Components are designed to be reused across different contexts and combined to build systems more efficiently
  • Loose coupling: Components interact through defined interfaces, minimizing dependencies on internal implementations of other components

Examples

  • Business function components: OrderProcessingService, CustomerManagementModule, PaymentGateway, InventoryTracker
  • Infrastructure components: AuthenticationService, LoggingFramework, CacheManager, MessageQueue
  • Layer-specific components: PersistenceComponent (data access), UIComponent (presentation), BusinessLogicComponent (domain rules)
  • Microservice-level: Each microservice in a distributed system acts as an independently deployable component

Why It Matters

Components are the fundamental unit of architectural organization and decision-making. They determine how systems are structured, deployed, tested, and evolved over time. Poor component boundaries lead to tight coupling, difficult maintenance, and limited scalability. Well-designed components enable independent development by different teams, support partial system updates, facilitate testing in isolation, and allow architectural characteristics (like scalability or security) to be applied at the appropriate scope. Component identification and boundaries represent critical architectural decisions with long-term consequences for system maintainability and evolution.

  • Modularity - Components are the physical packaging of modular units
  • Coupling - Component boundaries should minimize inter-component coupling
  • Functional-Cohesion - Components should maintain high internal cohesion
  • Bounded-Context - DDD bounded contexts often map to component boundaries
  • Architecture-Quantum - Components form part of architecture quantum structure

Sources

  • Richards, Mark and Neal Ford (2020). Fundamentals of Software Architecture: An Engineering Approach. O’Reilly Media. ISBN: 978-1-492-04345-4.

  • Ford, Neal, Mark Richards, Pramod Sadalage, and Zhamak Dehghani (2022). Software Architecture: The Hard Parts - Modern Trade-Off Analyses for Distributed Architectures. O’Reilly Media. ISBN: 9781492086895.

  • GeeksforGeeks (2024). “Difference Between Module and Software Component.” GeeksforGeeks System Design.

    • Components as independently deployable units vs modules as logical groupings
    • Available: GeeksforGeeks Article

  • The Essential Project (2024). “Software Components.” Enterprise Architecture University.

    • Components as major software elements representing identifiable business/infrastructure functions
    • Available: Essential Project

  • Mendix (2024). “What is Component-Based Architecture?” Mendix Blog.

    • Component-based development as industry standard with React’s 39.5% usage
    • Available: Mendix Blog

  • Wikipedia Contributors (2024). “Component-based software engineering.” Wikipedia.

    • CBSE definition: constructing systems from loosely coupled, reusable components
    • Available: Wikipedia

Note

This content was drafted with assistance from AI tools for research, organization, and initial content generation. All final content has been reviewed, fact-checked, and edited by the author to ensure accuracy and alignment with the author’s intentions and perspective.

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