Applying DDD and Event‑Storming to Design a Welfare Center Microservice

The project aims to develop a welfare‑center platform for employee interaction using microservices, applying Domain‑Driven Design (DDD) principles to replace the conventional three‑tier (presentation‑business‑data) architecture.

Technical Options : Two options are compared – the traditional three‑layer architecture, which relies on anemic data models and results in tight coupling between business logic and technology, and the DDD four‑layer architecture consisting of Adapter, Application, Domain, and Infrastructure layers. The former offers rapid development but suffers from poor encapsulation, business‑technology coupling, and maintenance challenges; the latter provides clear separation of concerns, better scalability, and aligns with microservice boundaries.

Event‑Storming Process : Participants (domain experts, DDD specialists, architects, product managers, developers, testers) gather in a workshop, use sticky notes to map out domain events, commands, and actors, and prepare materials (stickers, pens, tape) and a suitable wall space. The focus is on identifying entities, commands, events, and their relationships.

Domain Modeling : From the event‑storming output, the team extracts entities, value objects, aggregates, aggregate roots, domain services, and bounded contexts. Entities are modeled as rich (charging) objects containing both data and behavior. Value objects describe immutable concepts without unique identifiers. Aggregates group related entities/value objects, with a single aggregate root managing consistency.

Key Domain Elements include rules (commands like "Create Rule", "Execute Task" and events like "Rule Created"), employees (entity, commands such as "Select Employee"), welfare distribution (aggregate root "Welfare", commands for creating and executing distribution), logs, and the "Home Praise" (gift) system with commands for validation, execution, and events for completion. Messaging entities enable communication between bounded contexts via queues or event buses.

Summary : By using event‑storming to discover domain concepts and applying a DDD four‑layer architecture, the welfare‑center system achieves a clean separation between UI, application orchestration, core business logic, and technical infrastructure, facilitating microservice implementation, better maintainability, and scalability.