Library System with Design Patterns

This is a simple Java project demonstrating a library system that utilizes various design patterns including builder, singleton, decorator, and iterator.

Index

1. Prerequisites
2. Overview
3. Design Patterns Used
4. Resilience Patterns Used
5. Usage
6. Note
7. Contributors

Prerequisites

Before you begin, ensure you have met the following requirements:

• Maven >= 3
• Java >= 11

Overview

The project consists of the following components:

• Book: Represents a book in the library.
• Magazine: Represents a magazine in the library.
• LibraryItem: An interface representing items in the library, implemented by both Book and Magazine classes.
• Library: Implements the singleton pattern and represents the library. It manages the collection of items (books and magazines) and supports adding items with a capacity constraint. It also implements the iterator pattern to provide a way to iterate over its items.
• LibraryDecorator: An abstract class for extending functionality of the Library.
• IncreaseBooksCapacityDecorator: A concrete decorator to increase the books capacity of the Library.
• DecreaseBooksCapacityDecorator: A concrete decorator to decrease the books capacity of the Library.
• App: Contains the main method to demonstrate the library system.

Design Patterns Used

• Builder Pattern: Used in the Library, Book and Magazine classes to construct the library, book and magazine respectively.
• Singleton Pattern: Implemented in the Library class to ensure only one instance of the library exists throughout the application.
• Decorator Pattern: Implemented with LibraryDecorator and its concrete decorators (IncreaseBooksCapacityDecorator and DecreaseBooksCapacityDecorator) to extend the functionality of the Library dynamically.
• Iterator Pattern: Implemented by custom iterators in the Library class to iterate over the collection of items.

Resilience Patterns Used

• Retry Pattern: The Retry pattern allows the system to automatically retry failed operations with the expectation that they might succeed on subsequent attempts.

• Timeout Pattern: The Timeout pattern sets a maximum time for an operation to complete before it's considered unsuccessful, helping prevent long-running operations from causing delays or blocking resources indefinitely.

• Rate Limiting Pattern: The Rate Limiting pattern restricts the number of requests a system can handle within a specified time frame to prevent overload and ensure fair resource allocation.

• Circuit Breaker Pattern: The Circuit Breaker pattern helps handle failures gracefully by temporarily blocking requests to a service when it's deemed unavailable or experiencing a high failure rate, thereby preventing cascading failures and conserving resources.

You can modify the parameters related to these resilience patterns from the App.java file.

Usage

To run the project, first clone or download the repository to your local machine. Now, you have two options: using an IDE or using the CLI (terminal).

IDE

1. Open the project in your preferred Java IDE.
2. Run the App class.

CLI

mvn compile exec:java

The App class demonstrates the following functionalities:

• Creation of books and magazines.
• Adding items to the library.
• Displaying items in the library.
• Modifying the books capacity using decorators.
• Iterating over the library items using the Iterator pattern.

Note

In the ./assets/ directory, you can find a UML diagram of the project and the document adp_hw3.pdf, which contains a brief description of the application idea and discussions about design decisions and patterns used.

Contributors

• Lucas Catolino
• Santiago Lo Coco
• Joel Kudiyirickal