Design Patterns vs. Architectural Patterns

This article is a term explanation of the difference between design patterns and architectural patterns – including exam questions and tags.

In a Nutshell

Design patterns solve recurring problems in code at the class/object level. Architectural patterns structure the overall application at a higher level.

Compact Technical Description

• Design Patterns: tactical solutions (e.g., Singleton, Factory, Observer).
• Architectural Patterns: strategic macro structure (e.g., MVC, Layered/n-Tier, Microservices).

Both improve maintainability and reusability, but at different levels.

Exam-Relevant Key Points

• Design patterns = class level
• Architectural patterns = system level
• Design Patterns are often part of architectural patterns
• Architecture decisions affect scalability/costs (IHK-relevant)
• Both must be justified and documented

Core Components

1. GoF Patterns
2. Creational/Structural/Behavioral patterns
3. MVC
4. Layered Architecture
5. Microservices
6. EDA
7. DDD
8. UML Documentation

Practical Example

// Design Pattern: Factory
class UserFactory {
  public static User create(String name) {
    return new User(name);
  }
}

// Architectural Pattern: MVC
// Model = User.java, View = Frontend, Controller = Routing

Advantages and Disadvantages

Advantages

• Better readability/reusability (design patterns)
• Better teamwork/maintenance (architectural patterns)

Disadvantages

• Incorrect use leads to overengineering
• Architectural patterns increase initial effort

Typical Exam Questions (with Short Answer)

1. What is a design pattern? Reusable solution at the class level.
2. What is an architectural pattern? Structural approach for the entire software.
3. How are they related? Design patterns are used within an architecture.

Free Response

In exams, it is important to recognize whether the question asks for a solution at the code level or for the overall structure. Good architecture uses appropriate design patterns without unnecessary complexity.

Learning Strategy

1. Read patterns on Refactoring.Guru.
2. Draw UML for a design pattern and an architectural pattern.
3. Classify examples (design vs architecture).
4. Avoid pattern-itis.

Topic Analysis

• Core: Structure
• Challenges: Complexity
• Security: Layer separation
• Documentation: Diagrams/Justification
• Cost-effectiveness: Long-term maintenance

Further Information

1. https://refactoring.guru/design-patterns
2. https://martinfowler.com/architecture/