LearningApp: Microservices-Based Quiz Application

Github link: https://github.com/AnnaRandeberg/PG3402

Introduction

The goal of this project is to create a user-friendly learning app designed for middle school students. We've all experienced how reading school textbooks can sometimes feel boring, and it can be difficult to keep track of multiple subjects and curriculum demands. As the curriculum grows more challenging, our aim is to make learning easier and more enjoyable for the next generation.

Our solution is to turn learning into a fun, game-like experience. The app will feature quizzes subjects, with users receiving scores for each quiz. A leaderboard will allow students to compete with classmates, adding a layer of friendly competition that can be a strong motivator. Additionally, users will have access to making flashcards.

This project leverages microservice architecture to provide scalability, maintainability and flexibility for future enhancements. Key components include services for managing quizzes, scores, user authentication and flashcards, with RabbitMQ handling asynchronous communication and Consul ensuring service discovery.

How to Run the Project

1. Build the Project

To build the project, navigate to each service directory (pg3402/loginservice, pg3402/flashcardservice, pg3402/quizservice, pg3402/scoreservice, pg3402/gateway) and run the following command in the terminal:

mvn clean install

2. Start the Project

Once all services are built, navigate to the pg3402/docker folder and run the following commands (ps remember to have Docker Dekstop running in the background):

docker-compose down
docker-compose up --build -d

This will start all services as Docker containers.

3. Monitor Services

• Open Consul to check the status of all services:
  http://localhost:8500/ui/dc1/services
  Wait until all services are displayed as green in Consul:
  • gateway
  • loginservice
  • flashcardservice
  • scoreservice
  • quizservice
  • consul

4. H2 Database Console

Each service has an H2 database accessible through the following links:

Service	URL	JDBC URL	Username	Password
Login Service	http://localhost:8084/h2-console	jdbc:h2:file:~/learningapp	user	(none)
Quiz Service	http://localhost:8081/h2-console	jdbc:h2:file:~/learningapp	user	(none)
Flashcard Service	http://localhost:8087/h2-console	jdbc:h2:file:~/learningapp	user	(none)
Score Service	http://localhost:8082/h2-console	jdbc:h2:file:~/learningapp	user	(none)

5. RabbitMQ

RabbitMQ is used for asynchronous communication between services.
Access the RabbitMQ Dashboard at:
http://localhost:15672/
Username: guest
Password: guest

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Architecture

The system consists of the following microservices:

1. Login Service (Port: 8084)
2. Quiz Service (Port: 8081)
3. Flashcard Service (Port: 8087)
4. Score Service (Port: 8082)
5. Gateway (Port: 8080)

Communication types:

• Synchronous communication: REST calls via Gateway.
• Asynchronous communication: RabbitMQ for message passing.

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User Stories and API Endpoints

Below is a list of user stories that allow an examiner to assess the functionality developed in the project. These user stories represent key scenarios that demonstrate the features implemented in the application. Can be used on postman.

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1. User Story: Login/Register

As a middle school student,
I want to register/login,
So I can take quizzes and access the learning app.

• Register
  Method: POST
  URL: http://localhost:8084/api/users/register
  Body:

  {
      "email": "kally@gmail.com",
      "rawPassword": "secret123",
      "firstName": "Kally",
      "lastName": "Kai"
  }

• Login
  Method: POST
  URL: http://localhost:8084/api/users/login
  Body:

  {
      "email": "kally@gmail.com",
      "rawPassword": "secret123"
  }

Description: Users can register and log in using a secure process. Passwords are hashed to ensure data security and prevent plaintext storage in the database.

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2. Connect with Friends

As a user of the learning app,
I want to link with friends,
So I can see their quiz scores, compare progress, and motivate each other to improve.

• View All Users
  Method: GET
  URL: http://localhost:8084/api/users

• Search for a Specific User
  Method: GET
  URL: http://localhost:8084/api/users/search/Kally/Kai

Description: Users can view all registered users or search for specific friends using their first and last name. Sensitive information remains protected, as only non-critical data is displayed.

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3. Take Quiz

As a middle school student,
I want to take quizzes for various subjects and topics,
So that I can learn different subjects in a more engaging way and track my progress.

• View All Available Quizzes
  Method: GET
  URL: http://localhost:8081/quizapi

• Start a Quiz
  Method: POST
  URL: http://localhost:8081/quizapi/1/start
  Body:

  {
      "email": "kally@gmail.com"
  }

• Submit Answer
  Method: POST
  URL: http://localhost:8081/quizapi/1/answer
  Body:

  {
      "email": "kally@gmail.com",
      "questionId": "1",
      "answer": "4"
  }

Description: Students can view available quizzes, search for quizzes by ID, and submit answers. The system provides immediate feedback.

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4. Admin - Create Quiz

As an admin,
I want to create quizzes,
So that students can take them and test their knowledge.

• Create Quiz
  Method: POST
  URL: http://localhost:8081/quizapi
  Body:

  {
    "email": "admin@gmail.com",
    "title": "Science Grade 9",
    "chapter": "Fungi and Leaves",
    "subject": "Science",
    "questions": [
      {
        "questionId": 1,
        "questionText": "What is a fungus?",
        "correctAnswer": "A type of fungal structure"
      }
    ]
  }

• Find Quiz by ID
  Method: GET
  URL: http://localhost:8081/quizapi/quiz/1

Description: Only users with the admin email (admin@gmail.com) can create new quizzes. Unauthorized users are denied access.

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5. View Scores

As a student,
I want to see my quiz scores,
So I can understand my performance and track my progress.

• View Scores for All Users
  Method: GET
  URL: http://localhost:8082/scores

• View Score for a Specific User
  Method: POST
  URL: http://localhost:8082/scores/email
  Body:

  {
    "email": "kally@gmail.com"
  }

  Description: Users can view their quiz scores and compare progress with others.

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6. User Story: Flashcards

As a user,
I want to practice for my quizzes using flashcards,
So that I can improve my scores.

• See Flashcards for a Specific Quiz
  Method: GET
  URL: http://localhost:8087/flashcards/quiz/1

  Description: By integrating with the QuizService, users can fetch flashcards directly tied to quizzes. This promotes seamless interaction between services and demonstrates RESTful communication.

• Create a Flashcard
  Method: POST
  URL: http://localhost:8087/flashcards
  Body:

  {
    "questionText": "Hva er 5 + 3?",
    "answer": "8"
  }

  Description: This functionality allows users to create their own flashcards, similar to how they would in real life when studying. It supports personalized learning and adds interactivity to the application.

• Retrieve All Flashcards
  Method: GET
  URL: http://localhost:8087/flashcards

  Description: Retrieves all existing flashcards created by users.

Why Microservices?

Our project is well-suited for a microservices architecture because it addresses many challenges while making the system scalable and flexible. A monolithic architecture would not be ideal, as our system is divided into multiple services with a clear separation of responsibilities.

• Scalability: If the QuizService experiences heavy traffic, it can be scaled independently without affecting other services.
• Maintainability: Each service handles a specific functionality, making the code organized and easier to maintain.
• Resilience: Errors in one service do not affect the entire application, improving system robustness.
• Collaboration: With two developers working on this project, microservices allowed us to work on different services simultaneously without interfering with each other or the overall system.

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Technology Choices

For the database, we initially used Flyway for database migrations, as we had learned it in our backend programming course. However, we encountered numerous issues due to migration file conflicts. To avoid these conflicts and simplify database management, we switched to Spring Boot's built-in database initialization using data.sql. This approach provided better control and reduced complexity in our project.

Communication in the System

1. Synchronous Communication (REST Calls):

   • FlashcardService → QuizService: FlashcardService retrieves quiz data from QuizService using RestTemplate to make direct HTTP calls.
   • API Gateway → All Services: The API Gateway forwards incoming REST requests to the appropriate microservices using Spring Cloud Gateway.

2. Asynchronous Communication (RabbitMQ):

   • LoginService → RabbitMQ: When a new user is created, a UserCreatedEvent is published to the user.queue.
   • QuizService → RabbitMQ: After a quiz is completed, a QuizCompleteEvent is published to the quiz.complete queue.
   • ScoreService ← RabbitMQ: ScoreService listens to the quiz.complete queue to update user scores accordingly.

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Division of Work

• Candidate 81: Responsible for FlashcardService and QuizService.

• Candidate 70: Responsible for ScoreService and LoginService.

• Docker and Gateway: Shared responsibilities.

  Additionally, we used a lot of pair programming to solve problems, ensuring both of us contributed to all services equally. Each of us took responsibility for 50% of the workload, with a strong emphasis on collaboration to ensure that we were both actively involved in all parts of the project.

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References

• Data Initialization: Spring Boot - data.sql
• Microservice Diagram Creation: Kroki.io
• Project Inspiration: Bogdan Marculescu's Microservices Project