Teaching with living systems

This handbook was written to make microservices easy to teach. People remember stories and physical experiences far better than diagrams. This chapter gives you ready-to-use lesson plans for students, junior engineers, product managers — even non-technical stakeholders.

Three formats

60-minute talk outline

The role-play game: "The Café Society"

The most memorable exercise: people become microservices.

You need: 6–12 people, sticky notes, a whiteboard (the town square), envelopes (inboxes), name badges (ID cards), a timer.

Roles: Waiter, Chef, Cashier, Messenger (two people each if the group is large), plus customers and one chaos monkey (the facilitator).

Round 1 — The monolith (5 minutes)

One volunteer plays every role. Customers place orders as fast as they like. The single person is overwhelmed quickly. Discuss: what broke first?

Round 2 — Talking only (5 minutes)

Split into roles, but every hand-off must be face to face — the Waiter must walk to the Chef and wait for an answer before taking the next order. Discuss: what happens when the Chef is busy? (Everyone waits — synchronous coupling.)

Round 3 — The town square (5 minutes)

Now the Waiter writes OrderPlaced #n on a sticky note and pins it on the whiteboard; the Chef and Cashier copy notes into their own envelopes (inboxes) and work through them. Discuss: did the Waiter go faster? Who could join without the Waiter changing? (Add a "Loyalty" person mid-round.)

Round 4 — The rat race (5 minutes)

Customers order three times faster. The chaos monkey "makes the Chef sick" for 60 seconds. Discuss: did orders get lost? (No — they waited in the envelope.) What if the same note was read twice? (Idempotency!)

Round 5 — Memory rules (5 minutes)

Give the Cashier a private notebook. Someone tries to change the total in the Cashier's notebook directly. Discuss: why must each human own its memory?

Debrief questions:

1. Which round felt most like your current system at work?
2. Where did communication cause more problems than the work itself?
3. What lifestyle does your product live?

Paper exercises

1. Body check-up: pick a real service you know. Draw its body. Which organs are missing? (No skin? No pain receptors?)
2. Event storming: write the events of a library, a clinic or a ride-hailing app on sticky notes. Group them into humans.
3. Lifestyle diagnosis: for three apps on your phone, sketch their traffic shape and name their lifestyle.
4. Talk or letter? For ten interactions in the café, decide: talk (sync), letter (queue) or announcement (event)?

Quick quiz

1. In the analogy, what is a service's memory, and who may read it directly? (Its own database; only that service.)
2. What's the difference between a command and an event? (A request to do something vs a fact that happened.)
3. Why put a queue (inbox) between the town square and a worker? (Buffering, retries, dead-letter handling.)
4. Name two survival habits for a rat-race system. (Queues, throttling, provisioned concurrency, caching, backoff…)
5. What's the main danger of a chilling system? (Neglect: security and surprise costs.)
6. What is the DNA of a serverless human? (Its infrastructure as code — CDK.)

Written by Bipin Singh

Senior Full-Stack Engineer · AI & AWS. I design and build serverless systems on AWS — and love explaining them simply.

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