Explanation/Reference:
The application module is the "work unit" container that includes instances of the reusable view objects
required for the use case in question, related through metadata to the underlying entity objects in your
reusable business domain layer whose information the use case is presenting or modifying.
Your application module works with a Transaction object that acquires a database connection and
coordinates saving or rolling back changes made to entity objects.
The related Session object provides runtime information about the current application user.
References: http://docs.oracle.com/cd/E12839_01/web.1111/b31974/bcservices.htm#ADFFD1492