# Spring Boot Microservices

> Standards for synchronous (Feign) and asynchronous (Cloud Stream) communication

- Skill: `fierzone/spring-boot-microservices` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add fierzone/spring-boot-microservices`
- Raw SKILL.md: https://api.skillmd.com/api/skills/fierzone/spring-boot-microservices/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: DevOps & Infra
- Author: fierzone (https://skillmd.com/u/fierzone)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/fierzone/spring-boot-microservices

---


# Spring Boot Microservices Standards

## **Priority: P0**

## Implementation Guidelines

### Sync Communication (REST)

- **Clients**: Use **Spring Cloud OpenFeign** or **Http Interfaces** (Spring 6).
- **Resilience**: Wrap calls with **Resilience4j** (Circuit Breaker).
- **Contracts**: Define DTOs in a **Shared Library** (Maven BOM).
- **Versioning**: Enforce **Semantic Versioning** on shared libs.

### Async Communication (Event-Driven)

- **Cloud Stream**: Use `java.util.function.Consumer<T>` composition.
- **Idempotency**: Consumers MUST handle duplicates (DB constraints).
- **Evolution**: Add fields only. Never rename/remove used fields.

## Anti-Patterns

- **Direct DB Access**: `**No Shared DB**: Use APIs/Events.`
- **Coupled Entities**: `**No Shared Entities**: Use DTOs.`
- **Dist. Monolith**: `**No Sync Chains**: Use Async.`

## References

- [Implementation Examples](references/implementation.md)