The living systems idea
Software architecture is usually explained with boxes and arrows. People nod, then forget. But everyone already understands something far more complex than any software system: people. We know how a person senses the world, thinks, remembers, speaks, defends themselves and gets tired. We know how people work together in a society, and how different lifestyles feel.
This handbook uses that knowledge as a map. Once the map is in your head, microservices, serverless and cloud architecture stop being abstract.
The four big ideas
| In life | In software | Why the comparison works |
|---|---|---|
| One human body | One microservice | A complete, independent unit that can live on its own, with a clear purpose |
| Body parts | Modules inside the service | Each part has one job; together they make the body work |
| A society / ecosystem | A complete application | Many independent people, each with a role, cooperating through communication |
| A lifestyle | A kind of system | The same people behave differently in a rat race, a peaceful life or a lazy Sunday — and so do systems |
The body map in one table
| Body part | Module in a microservice | AWS example |
|---|---|---|
| Senses (eyes, ears, touch) | Inputs: APIs, events, queues, schedules, file uploads | API Gateway, EventBridge rules, SQS, S3 events |
| Skin | The boundary: input validation and the public contract | Request validation, schemas |
| Brain | Business logic — decisions and rules | Lambda function code |
| Memory | The service's own data | DynamoDB, S3 |
| Short-term memory | Cache | ElastiCache, in-memory caches |
| Voice | Responses and published events ("I've done this!") | API responses, EventBridge events |
| Ears for others | Subscriptions to other services' events | EventBridge rules, SNS subscriptions |
| Hands | Actions on the outside world: calling other systems | HTTP clients, AWS SDK calls |
| Immune system | Security — who can touch me, what I accept | IAM, Cognito, WAF, encryption |
| Heart and pulse | Health, metrics and alarms | CloudWatch, X-Ray |
| Diary | Logs | CloudWatch Logs |
| ID card | Identity and permissions of the service itself | IAM role |
| DNA | The code that builds the body, identically every time | AWS CDK |
The society map
| In society | In the application | AWS example |
|---|---|---|
| Each person has one job | Each service owns one business capability | One microservice per bounded context |
| Talking face to face | Synchronous request/response | HTTP APIs |
| Writing letters | Asynchronous messages | SQS queues |
| Town notice board | Publish/subscribe of events | EventBridge |
| Announcements on a loudspeaker | Fan-out notifications | SNS |
| A manager coordinating a project | Orchestrated workflows | Step Functions |
| City gate and reception | The single entry point for outsiders | API Gateway, CloudFront |
| Laws and shared services (police, roads, electricity) | Platform: identity, networking, monitoring | Cognito, VPC, CloudWatch |
| The world itself (air, food, land) | The cloud provider | AWS |
Lifestyles as systems
| Lifestyle | System character | Real examples |
|---|---|---|
| 🏃 Rat race | Always busy, huge spikes, strict deadlines, stress spreads quickly | Flash sales, ticket booking, trading, food delivery at dinner time |
| 🧘 Living in peace | Steady, balanced, predictable, calm under pressure | Business SaaS, banking back offices, HR systems |
| 😎 Just chilling | Mostly idle, wakes up occasionally, minimal cost | Personal apps, internal tools, prototypes, nightly reports |
The same "humans" (services) can live any of these lifestyles — what changes is how they're configured, connected and protected. That's the heart of architecture: designing for the life the system will actually live.
Keep three questions in mind throughout the handbook: Who is this human (what's its one job)? What is it made of (its modules)? What kind of life will it live (its lifestyle)?
How to read this handbook
- The idea — why we split systems into many humans, and what serverless means for them.
- Anatomy of one human — every body part, in depth, with AWS services.
- Growing a human from DNA — build one microservice from scratch with AWS CDK.
- The ecosystem — how many humans live and work together.
- Lifestyles — rat race, peace, chilling and more, as concrete system designs.
- Pilot: Café Sukoon — build a small but complete ecosystem step by step.
- Teaching — how to teach these ideas to others, and where the analogy stops working.
You don't need to know AWS already. Code examples use TypeScript, but every concept is explained in plain language first.
Senior Full-Stack Engineer · AI & AWS. I design and build serverless systems on AWS — and love explaining them simply.