Unlocking Code Reuse: Design Patterns, Frameworks, Architecture & Platforms Explained

1. Design Patterns

Design patterns are the most basic concept among the four, providing reusable solutions for specific problems by defining how classes, objects, and interfaces should be organized. For example, the Singleton pattern creates a globally unique configuration class.

2. Frameworks

Frameworks solve particular problems and often require further development. In web development, the most common frameworks are ORM frameworks such as NHibernate or ActiveRecord, as well as template and caching frameworks.

3. Architecture

Architecture addresses system‑level reuse, focusing on technology integration, scalability, and maintainability. A B2C website may combine multiple frameworks to meet business needs, and even framework development (e.g., building NHibernate) must consider architectural design.

4. Platforms

Platforms are higher‑level "frameworks" that combine architectural considerations to form enterprise‑grade applications, targeting business users and solving enterprise‑wide problems.

Design Patterns Classification

Creational (5): Factory Method, Abstract Factory, Singleton, Builder, Prototype.

Structural (7): Adapter, Decorator, Proxy, Facade, Bridge, Composite, Flyweight.

Behavioral (11): Strategy, Template Method, Observer, Iterator, Chain of Responsibility, Command, Memento, State, Visitor, Mediator, Interpreter.

Six Design Principles

Open/Closed Principle : software should be open for extension but closed for modification.

Liskov Substitution Principle : objects of a superclass should be replaceable with objects of a subclass without affecting correctness.

Dependency Inversion Principle : depend on abstractions, not concrete implementations.

Interface Segregation Principle : prefer many specific interfaces over a single general one to reduce coupling.

Demeter Principle (Least Knowledge) : each unit should know as little as possible about others.

Composite Reuse Principle : favor composition/aggregation over inheritance.

Framework Basics

A framework is a semi‑finished software product that provides core functionality, allowing developers to focus on the remaining features. For example, a typical Java web stack uses Struts for the presentation layer, Hibernate for persistence, and Spring for business logic.

Frameworks accelerate development by offering reusable components, enforcing a structured architecture, and reducing the amount of code developers must write from scratch.

Framework vs. Architecture vs. Design Patterns

Frameworks define the overall structure and responsibilities of an application, while architecture determines the high‑level organization and constraints. Design patterns offer language‑agnostic solutions to recurring design problems and can be applied within both frameworks and architectures.

Platform Overview

Java platforms include Java SE for desktop applications, Java EE for enterprise systems, and Java ME for mobile/embedded devices. Each platform provides a set of APIs and runtime environments tailored to its target devices.