E-commerce platform
Who uses it: Backend engineer designing service boundaries for an online store
Client → API Gateway
Gateway routes to User, Catalog, Cart, Order, Payment services
Order Service emits OrderCreated event to Kafka
Inventory Service reserves stock asynchronously
Notification Service sends email/SMS after order confirmation
Each core service owns its own database
Why this works: The diagram makes the most important boundary visible: orders, payments, and inventory should not share one database. Service autonomy depends on data ownership, not just separate code repositories.
SaaS collaboration product
Who uses it: Engineering team splitting a monolith into domain services
Workspace Service owns teams, members, and permissions
Document Service owns documents and version history
Comment Service handles threaded discussions
Realtime Gateway manages WebSocket connections
Event bus distributes document updates and notifications
Why this works: Collaboration products often mix synchronous requests with realtime events. Showing both paths helps reviewers decide which updates require immediate consistency and which can be eventually consistent.
Notification platform
Who uses it: Platform team building reusable notification infrastructure
Producer services → Notification API
Notification API validates templates and preferences
Kafka topic fans out to Email, SMS, Push workers
Delivery receipts return to Delivery Store
Admin UI reads delivery status and failure reasons
Why this works: A notification platform is a good microservices example because the producer services should not know how each delivery channel works. The diagram exposes that decoupling clearly.
Monolith to microservices migration
Who uses it: Tech lead planning a gradual architecture migration
Monolith remains behind API Gateway
Extract Auth Service first with clear token boundary
Extract Catalog Service with read-heavy database
Use events to sync data during transition
Retire monolith modules only after traffic is moved
Why this works: A migration diagram should show the temporary hybrid state. Teams get into trouble when they draw only the final architecture and ignore the transition path.
