http://www.cs.ru.nl/~fvaan/PV/what_is_a_good_model.html
https://en.wikipedia.org/wiki/View_model
https://en.wikipedia.org/wiki/4%2B1_architectural_view_model
https://www.uml-diagrams.org/
https://www.uml-diagrams.org/uml-core.html
https://www.uml-diagrams.org/use-case-diagrams.html
https://www.uml-diagrams.org/activity-diagrams.html