Component Stereotype and Their Design Layers
(4) Data/Operating System Layer Stereotypes
Entity Bean: An entity bean represents a business object in a persistent
storage mechanism. Some examples of business objects are customers, orders,
and products. In the J2EE SDK, the persistent storage mechanism is a relational
database. Typically, each entity bean has an underlying table in a
relational database, and each instance of the bean corresponds to a row in that
table.
The function of Data/Operating System Layer is to access the database of file
system. So the entity bean provides a method to access this data row
by row.