Design It!

Layers Pattern

The layers pattern is one of the most used (and abused) architecture patterns. Most software systems have multiple contributors. Partitioning code into distinct and independent layers organized around a specific set of related concerns enables developers to work together better. Layers promote decreased coupling between the layers and higher cohesion within, which promotes maintainability. Use layers any time you need to change code modules independently of one another.

Category	Module
Elements	Layer—group of functionally cohesive modules.
Relations	Allowed to use—indicates which layers may use modules within another layer.
Rules for Use	Every module must be allocated to one and only one layer. Layers above are allowed to use layers ...