What is meant by “N Tier”?

Some Number of Tiers or Layers

      1.      Logical and sometimes Physical separation

2.      May be deployed separately

3.      May be developed separately

Tiers and Layers

1.     Terms often used interchangeably
2.      Layer can be applied specifically to the logical structure of the application
3.     Tier can be applied specifically to the physical structure of the system infrastructure

Logical vs. Physical Separation

                        Logical separation refers to: Code organization

                        Namespaces, classes, folders, and assemblies

                        A software design pattern

                         

                        Physical separation refers to: Infrastructure organization

                        Separate physical processes, machines, devices

                        A software architecture

N Tier Diagram

Evolution of N-Tier Applications

Evolution of N-Tier Applications

Evolution of N-Tier Applications

Evolution of N-Tier Applications

Evolution of N-Tier Applications

Evolution of N-Tier Applications

Evolution of N-Tier Applications

Benefits of N-Tier Design

• Improved Productivity via Reuse
• Improved Productivity via Team Segmentation
• Improved Maintainability
• Looser Coupling
•   More Physical Deployment Options

Drawbacks and Risks of N-Tier Design

•   Reduced Performance, especially when physically separated
•     More Complex Design
•     More Complex Deployment