PorterDuff is described as a way of combining images as if they were "irregular shaped pieces of cardboard" overlayed on each other, as well as a scheme for blending the overlapping parts
A swarm is a number of Docker Engines (or nodes) that deploy services collectively. Swarm is used to distribute processing across many physical, virtual or cloud machines.
In the basic case, a model is Python class that maps to a single database table. The attributes of the class map to columns in the table and an instance of the class represents a row in database table. The models inherit from
django.db.models.Model which provides a rich API for adding and filtering results from the database.