Software Architecture Pattern 1: Layered Architecture

Objectives

Understand the layered architecture pattern
Design and implement a simple application using the n-tiered architecture
Perform analysis on a layered architecture pattern example

Metrics/Desired Outcomes

Understand the pattern description
Know the key concepts of layered architecture pattern
Identify shortcomings of the layered pattern
Analyze the 6 dimensions of the layered architecture pattern

Reading Assignment

Richards, Mark. Software Architecture Patterns. Chapter 1: Layered Architecture.

Pattern Description

Also known as the n-tier architecture pattern.
Found in most Java EE applications.
Organized as horizontal layers; each layer performs roles
Three (four) tiers: Presentation, Logic, Persistance (database)
Requests are passed from one layer to the next

Key Concepts

Separation of concerns
Each layer is self-contained
Cannot skip a layer
Layers are (should be interchangeable)
Closed vs. Open layer

Considerations

General purpose computing -- simple!
Easy to understand and can be implemented relatively easily
Sink hole occurs when data pass through a layer without touching it
80-20 rule to ensure architecture design is solid

Pattern Analysis

Agility
Ease of Deployment
Testability
Performance
Scalability
Ease of Development