🧠 Microservices Quiz Application

A fully backend Quiz Application built with Java Spring Boot following a Microservices Architecture. The application is decomposed into independently deployable services that communicate via REST, are discovered through a Eureka Service Registry, and are accessed through an API Gateway.

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📐 Architecture Overview

Client
  │
  ▼
┌──────────────────────┐
│      API Gateway      │  ← Port 8765
│  (Spring Cloud GW)   │
└──────────┬───────────┘
           │  Routes requests
    ┌──────┴──────┐
    ▼             ▼
┌─────────────┐  ┌─────────────┐
│  Quiz       │  │  Question   │
│  Service    │  │  Service    │
│  (Port 8090)│  │  (Port 8080)│
└──────┬──────┘  └──────┬──────┘
       │  Feign Client  │
       └────────────────┘
           ▲       ▲
           │       │
    ┌──────┴───────┴──────┐
    │    Service Registry  │  ← Port 8761 (Eureka)
    └─────────────────────┘

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🗂️ Project Structure

Microservices-QuizApplication/
├── GateWay/             # API Gateway (Spring Cloud Gateway)
├── QuestionService/     # Manages quiz questions (CRUD)
├── QuizService/         # Manages quizzes, generation, and scoring
└── Service-registry/    # Eureka Service Discovery Server

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🛠️ Tech Stack

Technology	Purpose
Java 17+	Core language
Spring Boot	Microservices framework
Spring Cloud Gateway	API Gateway and request routing
Spring Cloud Netflix Eureka	Service Discovery & Registration
Spring Data JPA	Data persistence / ORM
OpenFeign	Inter-service HTTP communication
PostgreSQL / MySQL	Relational database
Maven	Build tool
Postman	API testing

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📦 Services

1. 🔍 Service Registry (/Service-registry) — Port 8761

The Eureka Server acts as the service registry. All other services register themselves here, enabling dynamic service discovery without hardcoded URLs.

• Built with spring-cloud-starter-netflix-eureka-server
• Dashboard available at: http://localhost:8761

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2. ❓ Question Service (/QuestionService) — Port 8080

Responsible for all CRUD operations on quiz questions. Each question has a category, difficulty level, and multiple-choice options.

Key Endpoints:

Method	Endpoint	Description
GET	/question/allQuestions	Fetch all questions
GET	/question/category/{category}	Fetch questions by category
POST	/question/add	Add a new question
DELETE	/question/delete/{id}	Delete a question by ID
GET	/question/generate	Generate questions for a quiz
POST	/question/getScore	Calculate score from responses

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3. 📝 Quiz Service (/QuizService) — Port 8090

Orchestrates quiz creation and scoring by calling the Question Service via Feign Client.

Key Endpoints:

Method	Endpoint	Description
POST	/quiz/create	Create a quiz (category + limit)
GET	/quiz/get/{id}	Get quiz questions by quiz ID
POST	/quiz/submit/{id}	Submit answers and get score

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4. 🌐 API Gateway (/GateWay) — Port 8765

The single entry point for all client requests. Routes incoming requests to the appropriate microservice based on path predicates.

Route Configuration:

/question-service/**  →  Question Service
/quiz-service/**      →  Quiz Service

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🚀 Getting Started

Prerequisites

• Java 17+
• Maven 3.6+
• PostgreSQL or MySQL running locally
• Git

Setup & Run

Important: Services must be started in this exact order.

Step 1 — Clone the Repository

git clone https://github.com/Sathish292004/Microservices-QuizApplication.git
cd Microservices-QuizApplication

Step 2 — Configure the Database

In both QuestionService and QuizService, update src/main/resources/application.properties:

spring.datasource.url=jdbc:postgresql://localhost:5432/quizdb
spring.datasource.username=your_username
spring.datasource.password=your_password
spring.jpa.hibernate.ddl-auto=update

Step 3 — Start Service Registry (Eureka)

cd Service-registry
mvn spring-boot:run

Visit: http://localhost:8761 to confirm Eureka is running.

Step 4 — Start Question Service

cd ../QuestionService
mvn spring-boot:run

Step 5 — Start Quiz Service

cd ../QuizService
mvn spring-boot:run

Step 6 — Start API Gateway

cd ../GateWay
mvn spring-boot:run

All services should now be registered and visible in the Eureka dashboard.

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📬 Sample API Requests

All requests go through the API Gateway at http://localhost:8765.

Add a Question

POST http://localhost:8765/question-service/question/add
Content-Type: application/json

{
  "questionTitle": "What is JVM?",
  "option1": "Java Virtual Machine",
  "option2": "Java Verified Module",
  "option3": "Java Visual Manager",
  "option4": "None of the above",
  "rightAnswer": "Java Virtual Machine",
  "difficultyLevel": "Easy",
  "category": "Java"
}

Create a Quiz

POST http://localhost:8765/quiz-service/quiz/create
Content-Type: application/json

{
  "category": "Java",
  "numQuestions": 5,
  "title": "Java Basics Quiz"
}

Get Quiz Questions

GET http://localhost:8765/quiz-service/quiz/get/{quizId}

Submit Quiz & Get Score

POST http://localhost:8765/quiz-service/quiz/submit/{quizId}
Content-Type: application/json

[
  { "id": 1, "response": "Java Virtual Machine" },
  { "id": 2, "response": "Compile time" }
]

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🔄 Inter-Service Communication

The Quiz Service communicates with the Question Service using OpenFeign, a declarative REST client. Service discovery is handled automatically by Eureka — no hardcoded URLs are needed.

@FeignClient("QUESTION-SERVICE")
public interface QuizInterface {
    @GetMapping("/question/generate")
    ResponseEntity<List<Integer>> getQuestionsForQuiz(
        @RequestParam String categoryName,
        @RequestParam Integer numQuestions
    );
}

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📌 Key Concepts Demonstrated

• ✅ Microservices Architecture with Spring Boot
• ✅ Service Discovery with Eureka Server
• ✅ API Gateway with Spring Cloud Gateway
• ✅ Declarative REST Client with OpenFeign
• ✅ Inter-service Communication
• ✅ RESTful API Design with ResponseEntity
• ✅ JPA-based data persistence
• ✅ Separation of concerns across services

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🧪 Testing

Use Postman or cURL to test the APIs. Import the endpoints listed above and ensure all four services are running before making requests.

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🙌 Author

Sathish Kumar B — @Sathish292004

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📄 License

This project is licensed under an Educational Use Only License. See the LICENSE file for details.

© 2026 Sathish Kumar B. All rights reserved.