2nd/10_Wiki/Topics/Architecture/C4_Modeling_Framework.md

id, title, category, status, canonical_id, aliases, duplicate_of, source_trust_level, confidence_score, verification_status, tags, raw_sources, last_reinforced, github_commit, tech_stack

id	title	category	status	canonical_id	aliases	duplicate_of	source_trust_level	confidence_score	verification_status	tags	raw_sources	last_reinforced	github_commit	tech_stack
wiki-2026-0508-c4-modeling-framework	C4 Modeling Framework	10_Wiki/Topics	verified	self	C4 Model C4 Diagrams Simon Brown C4	none	A	0.9	applied	architecture c4 diagram structurizr documentation		2026-05-10	pending	language framework DSL Structurizr

C4 Modeling Framework

매 한 줄

"매 software architecture = 4 zoom levels (Context → Container → Component → Code).". 매 Simon Brown 이 2006년경 제안한 lightweight visualization framework. 매 2026 현재 Structurizr DSL + Mermaid C4 plugin 으로 diagram-as-code 가 standard, 매 audience-specific abstraction level 이 핵심 가치.

매 핵심

매 4 levels

• L1 — System Context: 매 system + users + external systems. 매 non-technical stakeholder 용.
• L2 — Container: 매 deployable unit (web app, API, DB, queue). 매 technical lead 용.
• L3 — Component: 매 container 내부 logical grouping (controller, service, repo). 매 dev team 용.
• L4 — Code: 매 class diagram (UML). 매 거의 안 그림 — IDE 가 대신.

매 supplementary diagrams

• Deployment diagram: 매 container → infrastructure node mapping.
• Dynamic diagram: 매 runtime sequence/collaboration.
• System landscape: 매 enterprise-wide multi-system view.

매 응용

1. Onboarding doc: 매 새 dev 의 codebase orientation.
2. ADR illustration: 매 architecture decision record 의 visual aid.
3. Stakeholder communication: 매 PM/exec 에게 system scope 설명.
4. Compliance audit: 매 data flow / boundary 시각화.

💻 패턴

Structurizr DSL (canonical)

workspace "Banking System" {
  model {
    customer = person "Customer"
    bankSystem = softwareSystem "Internet Banking" {
      webApp = container "Web Application" "Spring Boot" "Java"
      mobileApp = container "Mobile App" "React Native" "TypeScript"
      api = container "API" "Spring Boot" "Java"
      db = container "Database" "PostgreSQL" "RDBMS"

      webApp -> api "uses" "JSON/HTTPS"
      mobileApp -> api "uses" "JSON/HTTPS"
      api -> db "reads/writes" "JDBC"
    }
    mainframe = softwareSystem "Mainframe" "External"
    customer -> bankSystem "uses"
    bankSystem -> mainframe "fetches account data" "MQ"
  }
  views {
    systemContext bankSystem { include * autolayout }
    container bankSystem { include * autolayout }
    theme default
  }
}

Mermaid C4 (in-repo markdown)

C4Context
  title System Context — Banking
  Person(customer, "Customer")
  System(bank, "Internet Banking", "Allows customers to view accounts")
  System_Ext(mainframe, "Mainframe", "Legacy core banking")
  Rel(customer, bank, "Uses")
  Rel(bank, mainframe, "Fetches data", "MQ")

Component-level decomposition

api = container "API" {
  signInController = component "SignIn Controller" "Spring MVC"
  accountsController = component "Accounts Controller" "Spring MVC"
  authService = component "Auth Service" "Spring Bean"
  accountsRepo = component "Accounts Repository" "Spring Data JPA"

  signInController -> authService "uses"
  accountsController -> accountsRepo "reads"
  authService -> db "verifies credentials"
}

Deployment view

deploymentEnvironment "Production" {
  deploymentNode "AWS us-east-1" {
    deploymentNode "EKS Cluster" {
      containerInstance webApp
      containerInstance api
    }
    deploymentNode "RDS" {
      containerInstance db
    }
  }
}

Generated docs pipeline

# CI step — render diagrams from DSL
docker run --rm -v $PWD:/usr/local/structurizr structurizr/cli \
  export -workspace workspace.dsl -format plantuml/c4plantuml
plantuml -tsvg *.puml
mv *.svg docs/architecture/

ADR + C4 link

# ADR-007: Move auth to dedicated service
**Status**: Accepted
**Context**: See [Container diagram](../diagrams/banking-containers.svg)
**Decision**: Extract `authService` component into its own container.
**Consequences**: New diagram in `diagrams/v2-containers.svg`.

매 결정 기준

상황	Diagram level
Pitch to exec / new joiner intro	L1 Context
Tech selection / deployment plan	L2 Container
Code review / refactor discussion	L3 Component
Inheritance question	IDE (skip L4)
Multi-system enterprise view	System Landscape

기본값: L1 + L2 (둘만 있어도 90% communication 충족).

🔗 Graph

• 부모: Software_Architecture · Architecture_Documentation
• 변형: arc42 · 4+1_View_Model · UML
• 응용: ADR · Diagram_as_Code · Structurizr
• Adjacent: Mermaid · PlantUML · DDD

🤖 LLM 활용

언제: greenfield architecture 문서화, legacy reverse-engineering, ADR illustration. 언제 X: real-time runtime monitoring (observability tool 영역).

❌ 안티패턴

• All 4 levels for every system: 매 L4 거의 무의미 — IDE 대체.
• Mixing levels in one diagram: 매 abstraction 깨짐 → audience 혼란.
• No legend / inconsistent shapes: 매 reader 가 element type 못 구분.
• Diagram drift: 매 DSL 없이 manual draw → 6개월 후 stale.

🧪 검증 / 중복

• Verified (c4model.com — Simon Brown, Structurizr DSL spec 2024).
• 신뢰도 A.

🕓 Changelog

날짜	변경
2026-05-08	Phase 1
2026-05-10	Manual cleanup — C4 levels, Structurizr DSL, Mermaid C4 examples