38
Automated tests
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Java backend
Cham Orders API
Production-style order management REST API built with Java 21, Spring Boot, PostgreSQL, Flyway, Docker and OpenAPI.
Locally verified Release Candidate
Project overview
Context and approach
Overview
Cham Orders API is a transactional backend case study for managing users, customers, products and multi-item orders through a versioned REST contract.
Problem
Order systems must protect monetary calculations, preserve the historical state of purchased products and enforce authorization and lifecycle rules without leaking infrastructure details to clients.
Solution
A feature-first Spring Boot modular monolith applies JWT authentication, role-based authorization, server-side BigDecimal calculations, historical item snapshots, explicit state transitions and a consistent correlation-aware error contract.
Key figures
2
Flyway migrations
200
OpenAPI responses
59.85
Verified server total
Architecture
- 01
API Consumer
Authenticated REST requests and correlation IDs.
- 02
Spring Web
Versioned controllers, DTO validation and OpenAPI.
- 03
Application modules
Business rules, security and transactional services.
- 04
PostgreSQL
Persistent data, constraints and Flyway migrations.
Main capabilities
- JWT authentication and ADMIN/OPERATOR authorization.
- Customer, product and multi-item order management.
- Server-side monetary calculations with explicit mathematical limits.
- Historical product name, SKU and price snapshots.
- PENDING to CONFIRMED or CANCELLED transitions.
- Pagination, filtering and correlation ID propagation.
- Standardized HTTP errors, OpenAPI and Swagger UI.
Verification evidence
- 38 automated tests passed.
- Maven clean test and clean package passed.
- Docker image built and PostgreSQL 17.10 reported healthy.
- Flyway V1 and V2 applied successfully.
- OpenAPI JSON and YAML returned HTTP 200.
- Docker-backed release-candidate smoke test passed.
- Clean-clone verification passed.
Engineering decisions
- — The server is the only authority for subtotals and totals.
- — Order items store historical product snapshots.
- — Expected HTTP failures share one stable error contract.
- — Flyway exclusively manages the PostgreSQL schema.
- — Correlation IDs are propagated when safe and generated otherwise.
Scope limitations
- — No public or production deployment.
- — No refresh tokens, payments, inventory, shipping or messaging.
- — No Testcontainers suite or remote CI execution yet.
- — Advanced observability and measured query optimization remain outside the MVP.
Review the implementation
Source code, documentation and reproducible local instructions are available on GitHub.