Data Labeling Support System

Data Labeling Support System (DLSS) is a web application for managing image annotation projects. It supports dataset upload, label taxonomy management, task assignment, bounding-box annotation, reviewer approval, audit logging, project dashboards, and COCO export for object-detection training pipelines.

The project is organized as a React frontend and a Spring Boot backend with a PostgreSQL database.

Architecture

flowchart LR
    User[Browser users] --> Frontend[React/Vite frontend]
    Frontend --> API[Spring Boot REST API]
    API --> DB[(PostgreSQL)]
    API --> Storage[Local upload directory or Cloudinary]
    API --> Export[COCO JSON / ZIP package]

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Core Roles

Role	Main responsibility
ADMIN	Manage users, groups, projects, system configuration, dashboards, audit logs, and global data access.
MANAGER	Create projects, attach datasets, define labels, assign or split tasks, monitor progress, and export completed annotations.
ANNOTATOR	View assigned projects/tasks, draw bounding boxes, save work, and submit ready images for review.
REVIEWER	Review submitted annotations, approve valid tasks, reject invalid tasks, and provide defect feedback.

Main Capabilities

• Authentication with JWT and role-based access control.
• User and group management, including manager-scoped annotator/reviewer access.
• Project CRUD with soft delete, manager assignment, reviewer assignment, labels, files, and task statistics.
• Dataset CRUD, image upload, sample metadata, pagination, and soft delete.
• Task generation from datasets, assignment to annotators, workload reporting, and split by equal share or percentage.
• Annotation storage for normalized bounding boxes in JSONB.
• Review queue with approval, rejection, defect categories, review history, and review statistics.
• Dashboards for managers and administrators.
• Performance analytics for users and projects.
• COCO export as JSON and ZIP package with images and an export manifest.
• Activity logging for audited API actions.

Tech Stack

Layer	Technology
Frontend	React 19, Vite 7, React Router, Axios, Tailwind/PostCSS, lucide-react, framer-motion
Backend	Java 21, Spring Boot 4, Spring Security, Spring Data JPA, Spring Validation, Spring MVC
Database	PostgreSQL, JSONB columns, Flyway migration files
API docs	springdoc OpenAPI / Swagger UI
Storage	Local filesystem by default, optional Cloudinary strategy
Tests	JUnit, Spring test modules, H2 for test profile, frontend ESLint/build

Repository Structure

backend/
  src/main/java/com/uth/datalabeling/
    common/          Shared responses, exceptions, storage helpers
    config/          Security, CORS, Swagger, Cloudinary config
    modules/         Feature modules by domain
    security/jwt/    JWT provider, filter, entry point, access denied handler
  src/main/resources/
    db/migration/    Database evolution scripts
frontend/
  src/pages/         Role-based screens
  src/components/    Shared UI and role-specific components
  src/services/      Axios API clients
docs/
  api-reference.md
  system-design.md
  testing-validation.md
database-schema.md

Run Locally

Start PostgreSQL and pgAdmin:

docker compose up -d

Run the backend:

cd backend
./mvnw spring-boot:run

Run the frontend:

cd frontend
npm install
npm run dev

Default local URLs:

Service	URL
Frontend	http://localhost:5173
Backend API	http://localhost:8080/api/v1
Swagger UI	http://localhost:8080/api/v1/swagger-ui/index.html
pgAdmin	http://localhost:5050

Configuration

Backend configuration is driven by environment variables with defaults in backend/src/main/resources/application.properties.

Variable	Default	Purpose
SERVER_PORT	8080	Backend HTTP port
CONTEXT_PATH	/api/v1	API context path
DB_URL	jdbc:postgresql://localhost:5432/datalabeling	PostgreSQL JDBC URL
DB_USERNAME	postgres	Database user
DB_PASSWORD	secret	Database password
JWT_SECRET	development secret	JWT signing key
JWT_EXPIRATION	3600	Token lifetime in seconds
CORS_ALLOWED_ORIGINS	local frontend origins	Allowed browser origins
UPLOAD_DIR	uploads/	Local upload root
STORAGE_STRATEGY	local	local or cloudinary
CLOUDINARY_URL	empty	Cloudinary connection string

Documentation

• System design
• API reference
• Database schema
• Testing and validation

Verification

Backend:

cd backend
./mvnw -q -DskipTests compile
./mvnw test

Frontend:

cd frontend
npm run lint
npm run build