3.2.6.Layered system

• Client-server architecture consist of multiple layers

  • 1.No one layer can see past the next

    • e.g., Gateway不知道database是怎麼被設定的

      

  • 2.Layers may be added, removed or modified based on needs

    • e.g.加入Load balancer, 多個server但不會對client有影響

    

  • 3.Client must never connect directly to the app server

    • Client should not have to distribute requests

    

• Benefits

  • Layering simplifies the architecture - hides the complexity

  • The architecture nay evolve with the changing needs

  • Clients does not need to worry about request distribution