Module
Module 2 of 6Lesson 1 of 2~16 min

Reading an architecture diagram with the C4 model

Reading an architecture diagram lets a PM check whether a proposal actually addresses the problem at hand. The lesson uses the C4 model to spot what a diagram shows, what it leaves out and where trust boundaries sit, then to turn each blind spot into a precise question before the sign-off meeting.

Take this lesson: your first course is freeSee the full syllabus

Lesson objective

By the end of this lesson, you will be able to read an architecture diagram at the context and container levels of the C4 model, spot users, external systems, containers, flows and trust boundaries, and turn its gray areas into questions for the team.

Topics covered

  • C4 model
  • architecture diagram
  • system context diagram
  • container diagram
  • trust boundary

Where it fits

Reading an architecture

How do you read an architecture diagram and state precisely what the system must guarantee?

Lessons in this module

  1. Reading an architecture diagram with the C4 model (this lesson)
  2. From vague expectations to measurable requirements

What you will learn in the course

This lesson is part of the course Read and challenge a technical architecture

  • Read an architecture diagram (context and container levels of the C4 model) and spot its components, flows, boundaries and gray areas.
  • Turn vague expectations ("fast", "reliable", "scalable") into measurable non-functional requirements, written as quality attribute scenarios.
  • Compare monolith, modular monolith and microservices, then synchronous calls and asynchronous processing, based on the team, the load and the consequences for the user.
  • Assess data choices (source of truth, transactions, replicas, consistency), scaling and caching, and spot the bottleneck of a user journey.
  • Assess dependencies on third-party services (composite availability, degraded mode, vendor lock-in) and a build or buy decision.
  • Frame an architecture trade-off, record it in an ADR and treat technical debt as a product decision.
  • Run an architecture review of your product or of a proposal, with ten questions, a risk register and explicit trade-offs.

Related courses