Layered Architecture and Domain‑Driven Design for Java Fresh‑Food E‑Commerce Microservices

The article explains how to combine layered architecture with Domain‑Driven Design (DDD) to build a microservice system for a Java fresh‑food e‑commerce platform, advocating a five‑layer structure: infrastructure, domain service, application service, gateway, and user‑interface.

It recounts the author’s background, the evolution of DDD since the early 2000s, and the need for a unified “ubiquitous language” among product managers, architects, and developers, while noting the difficulty of strict DDD adoption in many Chinese companies.

The layered design section defines each layer’s responsibilities, adds a gateway layer to handle external HTTP traffic and security, and stresses principles such as intra‑layer cohesion, dependency on lower layers only, and loose coupling via middleware.

Domain partitioning guidance covers clear functional boundaries, incremental splitting from monolith to microservices, handling sub‑domains, and keeping domain services independent of callers, illustrated with a fruit‑selling and hardware‑selling case study.

The Q&A part discusses why each layer should use its own model (DBO, DMO, DTO), the drawbacks of reusing persistence models across layers, the necessity of an application layer for data filtering and contract stability, and the role of the gateway in exposing services.

In conclusion, the author emphasizes that a well‑designed microservice architecture is crucial for large Java e‑commerce applications, and hopes the shared experience helps practitioners avoid common pitfalls and build robust systems.