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:
Layer vs IO - Locality
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, ..) |