Day 5Level 1 — Core Mental Models
C4 Modelling: Context, Containers, Components, Code
Learn: 45 minMap: 30 minDesign: 60 min
Core Concepts (5)
- 1.C4 gives you 4 zoom levels: System Context → Containers → Components → Code
- 2.Context diagram: who uses it, what external systems touch it
- 3.Container diagram: deployable units (services, databases, queues, SPAs)
- 4.Component diagram: internal structure of a container (modules, classes)
- 5.Diagrams as code (Mermaid/Structurizr) = versionable, reviewable, diffable
Map to Your Experience
Draw the Context and Container diagrams for your system. What external systems did you miss on first pass?
Design Brief: C4 Context & Container Diagrams
Requirements
- •Context diagram shows all actors and external systems
- •Container diagram shows all deployable units
- •Technology choices labelled on each container
- •Data flows and protocols indicated
- •Rendered as Mermaid (text-based)
Constraints
- •Mermaid syntax only — no drag-and-drop tools
- •Must be valid C4 notation
Must Cover
context-diagramcontainer-diagramtechnology-labelsdata-flows
Trade-off Axis
diagram detail vs maintenance burden
Referenced Patterns
Competencies Advanced
distribution communication → L2requirements constraints → L2
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