Requirements

Let's enhance our Learning Management System (LMS). Imagine you are building a system to manage courses, modules, lessons, and user progress. This system needs to be flexible enough to accommodate different types of lessons (e.g., video, quizzes, assignments) and user roles (e.g., student, instructor, admin). The current system has limitations in extensibility and maintainability. Adding new lesson types or user roles requires significant code modifications and increases the risk of introducing bugs. Concurrency is also a concern, as multiple users might access and update course content simultaneously. This problem focuses on designing a robust and scalable LMS using Object-Oriented Design principles. We want to create a system that is easy to extend, maintain, and test. The system should also handle concurrent access to data safely. # Requirements ## Functional Requirements 1. **User Management:** * Support different user roles: Student, Instructor, and Admin. * Each user should have attributes like ID, name, email, and role. * Allow admins to create, update, and delete users. * Allow instructors to create, update, and delete courses they own. * Students can enroll in courses. 2. **Course Management:** * Courses have attributes like ID, name, description, and instructor. * Courses are composed of modules. * Allow instructors to create, update, and delete courses they own. * Allow students to enroll in courses. 3. **Module Management:** * Modules have attributes like ID, name, and description. * Modules are composed of lessons. * Allow instructors to add, update, and delete modules in their courses. 4. **Lesson Management:** * Support different lesson types: Video, Quiz, Assignment. * Each lesson type has specific attributes (e.g., video URL, quiz questions, assignment description). * Allow instructors to add, update, and delete lessons in their modules. * Support tracking lesson completion status for each student. 5. **Enrollment and Progress Tracking:** * Students can enroll in courses. * The system should track the progress of each student in each course (e.g., lessons completed, quiz scores, assignment submissions). * Provide reports on student progress. 6. **Concurrency:** * Multiple users should be able to access and update course content simultaneously without data corruption. * Ensure thread-safe operations for enrollment, progress tracking, and content updates. ## Non-Functional Requirements 1. **Extensibility:** The system should be easily extensible to support new lesson types, user roles, and features without requiring significant code changes. Consider using design patterns that allow for adding new functionality without modifying existing code. 2. **Maintainability:** The code should be well-structured, modular, and easy to understand. Use clear naming conventions, comments, and consistent coding style. Focus on reducing code duplication and increasing code reusability. 3. **Testability:** The system should be designed to be easily testable. Use interfaces and dependency injection to facilitate unit testing. Consider how to mock external dependencies. 4. **Thread Safety:** Ensure that all shared data structures are accessed in a thread-safe manner. Use appropriate synchronization mechanisms to prevent race conditions and data corruption. Pay attention to potential bottlenecks and optimize for concurrency. 5. **Modularity:** Decompose the system into loosely coupled modules with well-defined interfaces. This will improve maintainability, testability, and reusability. Aim for high cohesion within modules and low coupling between modules. 6. **SOLID Principles:** Adhere to the SOLID principles of object-oriented design to create a robust and maintainable system. Consider how each principle (Single Responsibility, Open/Closed, Liskov Substitution, Interface Segregation, Dependency Inversion) applies to different aspects of the design. ## Core Entities 1. **User:** Represents a user of the LMS. Attributes: ID, name, email, role. Methods: `enroll(Course)`, `getEnrolledCourses()`, `getRole()`. 2. **Role:** An enum representing the role of a user (Student, Instructor, Admin). Each role has associated permissions. 3. **Course:** Represents a course in the LMS. Attributes: ID, name, description, instructor (User). Methods: `addModule(Module)`, `getModules()`, `enrollStudent(User)`. 4. **Module:** Represents a module within a course. Attributes: ID, name, description. Methods: `addLesson(Lesson)`, `getLessons()`. 5. **Lesson:** Abstract class or interface representing a lesson. Attributes: ID, name. Subclasses: VideoLesson, QuizLesson, AssignmentLesson. Consider using a factory pattern for creating different lesson types. 6. **VideoLesson:** Concrete Lesson type. Attributes: videoUrl. 7. **QuizLesson:** Concrete Lesson type. Attributes: questions (List of Question objects). 8. **AssignmentLesson:** Concrete Lesson type. Attributes: description, dueDate. 9. **Enrollment:** Represents a student's enrollment in a course. Attributes: student (User), course (Course), enrollmentDate. 10. **Progress:** Tracks a student's progress in a course. Attributes: student (User), course (Course), lessonCompletionStatus (Map ), quizScores (Map ), assignmentSubmissions (Map ). Consider thread-safe data structures for `lessonCompletionStatus`, `quizScores`, and `assignmentSubmissions`. 11. **LMS:** The main class that orchestrates the LMS functionality. Manages users, courses, and enrollments.

Design Learning Management System

Requirements

Interview Simulation

Functional Requirements

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Non-Functional Requirements

Core Entity Identification

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