Classes in an application can be grouped together based
on the types of work that they do in the application,
which is known as layers.
o Foundation layer, problem domain layer, data management
layer, human-computer interaction layer, and physical
architecture layer
• This lecture emphasizes the data management layer
o Data access and manipulation logic
• How data are stored and handled by the programs that run the system
o Actual design of the storage
• How to design object persistence or the storage for objects (a fourstep
process)