c4-architecture-documentation

C4 Architecture Documentation Skill

Purpose

Document CIA platform architecture using C4 model for different abstraction levels.

When to Use

• ✅ Documenting system architecture
• ✅ Onboarding new developers
• ✅ Architecture decision records
• ✅ Security architecture reviews

C4 Model Levels

Level 1: System Context

[External Users] --uses--> [CIA Platform] --uses--> [Riksdagen API]
[CIA Platform] --uses--> [World Bank API]
[CIA Platform] --uses--> [PostgreSQL Database]

Level 2: Container Diagram

[Web Browser] --HTTPS--> [Spring MVC App] --JDBC--> [PostgreSQL]
[Spring MVC App] --HTTPS--> [External APIs]
[Spring MVC App] --uses--> [Redis Cache]

Level 3: Component Diagram

// Service Layer Components
@Component PoliticianService --uses--> @Repository PoliticianRepository
@Component VotingAnalysisService --uses--> @Repository VotingRecordRepository
@Component RiksdagenClient --calls--> [External Riksdagen API]

Level 4: Code

// Detailed class design
public class PoliticianService {
    private final PoliticianRepository repository;
    private final RiksdagenClient riksdagenClient;
    // Implementation details...
}

PlantUML Diagrams

@startuml
!include https://raw.githubusercontent.com/plantuml-stdlib/C4-PlantUML/master/C4_Container.puml

Person(user, "Citizen", "Wants political transparency")
System_Boundary(cia, "CIA Platform") {
    Container(web, "Web Application", "Spring MVC, Vaadin 8", "Provides UI")
    ContainerDb(db, "Database", "PostgreSQL", "Stores data")
}
System_Ext(riksdagen, "Riksdagen API", "Government data")

Rel(user, web, "Uses", "HTTPS")
Rel(web, db, "Reads/Writes", "JDBC")
Rel(web, riksdagen, "Fetches data", "HTTPS/REST")
@enduml

References

• C4 Model: https://c4model.com/
• ARCHITECTURE.md
• FUTURE_ARCHITECTURE.md