As shown in the following figure, a servlet typically invokes a command (such as a request to an entity EJB) and then invokes the JSP program to display the result:

Depending on the results that get returned, the servlet can invoke a different JSP program. For the results bean associated with the JSP program, a call to retrieve an attribute should have the following characteristics:
A Java™ bean wrapper or EJB factory does not meet the requirement for the JSP programming model, because every call is a remote call that can throw a remote exception and has a long execution call path. A copy helper or data class resolves this problem.
An AccessBeanData interface class containing abstract representations
of the getter and setter methods is generated when the access bean
is created. The access bean class implements this interface, which
can be used as a data object in a JSP that is independent of the access
bean implementation. A data class containing getters and setters for
the cache properties can also be generated. It extends the AbstractEntityData
class.