Ans: All of these features can be summarized by saying that using ADF Business Components for your J2EE business service layer makes your life a lot easier. The key ADF Business Components components that cooperate to provide the business service
implementation are:
■Entity Object
An entity object represents a row in a database table and simplifies modifying its data by handling all DML operations for you. It can encapsulate business logic for the row to ensure your business rules are consistently enforced. You associate an entity object with others to reflect relationships in the underlying database schema to create a layer of business domain objects to reuse in multiple applications.
■Application Module
An application module is the transactional component that UI clients use to work with application data. It defines an up datable data model and top-level procedures and functions (called service methods) related to a logical unit of work related to an end-user task.
■View Object
A view object represents a SQL query and simplifies working with its results. You use the full power of the familiar SQL language to join, project, filter, sort, and aggregate data into exactly the “shape” required by the end-user task at hand. This includes the ability to link a view object with others to create master/detail
hierarchies of any complexity. When end users modify data in the user interface,your view objects collaborate with entity objects to consistently validate and save the changes
