Spring Boot Process API Basics

Java 21 · Spring Boot · REST API · Spring Data JPA · H2 · Validation · Maven

Small Java 21 / Spring Boot learning project that exposes process-check data through a simple REST API.

Project page: https://datatidehh.github.io/spring-boot-process-api-basics/

This repository is part of my broader DataTideHH portfolio. It supports my learning path toward Data/BI and process-oriented IT roles by connecting Java/Spring backend basics with structured operational process data.

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Purpose

The project focuses on a deliberately small backend use case: storing and exposing process-check records.

It demonstrates:

• REST endpoints for a small process-related resource
• layered backend structure with controller, service and repository
• request validation
• basic persistence with Spring Data JPA
• an H2 in-memory database for local development
• a local Maven build and test workflow
• synthetic sample data for process-oriented API testing

The goal is not to present a large enterprise backend. The goal is to document a clean first step from Java basics toward a small Spring Boot REST API that handles structured process data.

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Portfolio Context

For Data/BI and process analysis work, APIs are an important interface between operational systems and downstream data workflows.

This project is useful as a supporting IT foundation because it shows how process-related records can be represented, validated, persisted and exposed through a small HTTP API.

It complements my main Data/BI portfolio projects around SQL, Python, Power BI, data quality and process-oriented analysis.

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Tech Stack

Layer	Tool / Concept	Purpose
Language	Java 21	Main implementation language
Framework	Spring Boot	REST API application framework
API layer	Spring Web	HTTP endpoints and JSON responses
Persistence	Spring Data JPA	Repository abstraction and entity persistence
Database	H2	In-memory local development database
Validation	Jakarta Validation	Request validation for incoming data
Build tool	Maven Wrapper	Reproducible local build workflow

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Architecture

HTTP client
    -> ProcessCheckController
        -> ProcessCheckService
            -> ProcessCheckRepository
                -> H2 in-memory database

Current package focus:

src/main/java/de/datatidehh/processapi/processcheck/

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API Endpoints

Method	Endpoint	Purpose
GET	/api/process-checks	Return all process-check records
GET	/api/process-checks/{id}	Return one process-check record by ID
POST	/api/process-checks	Create a new process-check record
PUT	/api/process-checks/{id}	Update an existing process-check record
DELETE	/api/process-checks/{id}	Delete a process-check record

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Example Process-Check Record

{
  "id": 1,
  "processName": "Daily sales import",
  "owner": "Data Operations",
  "status": "OK",
  "lastCheckedAt": "2026-07-10T00:25:00",
  "slaMinutes": 60
}

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Run Locally

From the repository root:

./mvnw spring-boot:run

Then open:

http://localhost:8080/api/process-checks

At first startup, the API returns an empty JSON array because the H2 database is empty:

[]

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Build and Test

Run:

./mvnw clean package

The project has been built and smoke-tested locally with Java 21 and the Maven Wrapper.

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Manual API Test Flow

The API was manually tested with curl for the full CRUD flow:

POST   /api/process-checks       create a process-check record
GET    /api/process-checks       list all process-check records
GET    /api/process-checks/1     read one process-check record
PUT    /api/process-checks/1     update one process-check record
DELETE /api/process-checks/1     delete one process-check record

Example test data:

processName: Daily sales import
owner: Data Operations
status: OK / WARNING
lastCheckedAt: 2026-07-10T00:25:00
slaMinutes: 60

After deletion, the list endpoint returns an empty JSON array again.

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H2 Database Note

This project uses an H2 in-memory database for local development and API testing.

That means:

• no external database server is required
• the database is recreated when the application starts
• inserted records are lost when the application stops
• this is suitable for a small learning project, not for production persistence

The H2 console is available locally while the application is running:

http://localhost:8080/h2-console

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GitHub Pages Project Site

This repository includes a small project landing page under:

docs/index.md

Published project page:

https://datatidehh.github.io/spring-boot-process-api-basics/

GitHub Pages settings:

Source: Deploy from a branch
Branch: main
Folder: /docs

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What This Demonstrates

This repository demonstrates a small but realistic backend foundation:

• Java 21 project workflow
• Spring Boot application structure
• REST endpoint design
• JSON request and response handling
• CRUD operations
• layered backend organization
• request validation
• basic persistence abstraction with Spring Data JPA
• local development with H2
• Maven build and test workflow
• public portfolio documentation for a focused learning project

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Limitations

This is a learning project.

It does not include production database configuration, Docker deployment, a frontend UI, cloud deployment, monitoring infrastructure or enterprise-scale error handling.

These omissions are intentional. The current scope is limited to a clean, understandable Spring Boot REST API baseline.

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License

This project is licensed under the MIT License. See the LICENSE file for details.