Like most business components, individual entity objects are partially defined by XML files. These files specify: 1. Simple metadata about the datasource, such as the table name and attribute definitions and 2. Simple business logic, such as the business logic that represents most column constraints and simple validation and security logic. In addition to XML files, entity object definitions comprise up to three Java classes: a) The entity object class - an instance of this class (an entity object instance) represents a single row from the datasource ( oracle.jbo.server.EntityImpl ) b) The entity collection class - an instance of this class represents the collection of rows currently in memory for a single user( oracle.jbo.server.EntityCache ) c) The entity definition class - the singleton instance of this class represents the entire datasource object( oracle.jbo.server.EntityDefImpl ) To access an entity row, you use a related object called the entity definition. At run...