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About

A layer is the implementation of abstraction.

From a high level, each language generation are a layer.

A layer is built based on recurring pattern. If a lower layer has a recurring pattern, it is taken out of it, and build in the higher layer.

Boundary definition. A layer can be seen:

  • as a module that is located inside a stacked architecture of modules.
  • or as a way the internal components of module will interact with each other.

Layer vs IO - Locality

Three principal layers

Layer Functionality
Presentation Provision of services, interface (HTML, Rich Client), handling of user request (click, …)
Domain (Business Logic) Logic (procedural and calculation)
Data Source Communication with the data sources (database, file, ..)

Documentation / Reference