Multi-Tier Architecture

• The service is broken down into multiple independent (logically and physically) tiers
• Each tier communicates only with the tier above it

Three-Tier

• One of the most common architecture patterns for web-based systems
• Tiers
• Presentation Tier
• Application Tier

• Data Tier

• One flaw is the monolithic structure of the logic tier, which starts becoming too chaotic for large systems

Presentation Tier

• Presentation Tier

• User Interface

• This tier should not contain any business logic

• The user can change this code!

• Responsibilities

• Display information to the user

• Take the user's input

• Examples

• A webpage
• A mobile app
• A desktop application

Application Tier

• Application Tier
• Business Tier

• Logic Tier

• Responsibilities

• Provide all the functionalities and features
• Process data from the presentation tier

• Apply business logic to it

• Examples

• Services

Data Tier

• Responsibilities

• Store and persistence of user and business-specific data

• Examples:

• Files in the filesystem
• Database

Two-Tier

• Presentation + Application together
• It's common on simple apps. E.g., notes app

Four-Tier

• An additional layer of security between the presentation and the application