Some doubts on - Mikalai Zaikin study material

[Narasimha Rao B.]

Hi,
I am having some doubts on the study guide provided by, Mikalai Zaikin.
Please clarify the same.

Notation, i will type every thing from the material in quotes and my doubts without quotes.

1. Section - "Identify correct and incorrect statements or examples about EJB programming restrictions. "Material says, "The enterprise bean must not attempt to define a class in a package."
Doubt --> What it means exactly? Is it means bean shouldn't be defined in the package?

2. Chapter 3 -- Section - "Identify the use and the behavior of the ejbPassivate method in a session bean, including the responsibilities of both the container and the bean provider. "
subsection - "Container's responsibility"
Material says - "The container may destroy a session bean instance if the instance does not meet the requirements for serialization after ejbPassivate."
Doubt --> Is it means, if the bean does not meet the requirements for passivation at the end of ejbPassivate() method, bean is destroyed? Is it true? I have read, if any of the member variables does not meet the requirements for passivation, container simply ignore those variables and the variables will be destroyed and the bean can't use the same varibales once the bean is activated by ejbActivate() method.

3. Chapter 3 : Section - "Match the correct description about purpose and function to which session bean type they apply: stateless, stateful, or both."
Material Says:- "The conversational state of a STATEFUL session object is defined as the session bean instance�s field values, plus the transitive closure of the objects from the instance�s fields reached by following Java object references."
Doubt --> What is the meaning of, -- ' transitive closure of the objects from the instance�s fields reached by following Java object references. '

Thanks in Advance..

[Valentin Crettaz]

1. Section - "Identify correct and incorrect statements or examples about EJB programming restrictions. "Material says, "The enterprise bean must not attempt to define a class in a package."
Doubt --> What it means exactly? Is it means bean shouldn't be defined in the package?

https://coderanch.com/t/159007/java-EJB-SCBCD/certification/package-class

2. Chapter 3 -- Section - "Identify the use and the behavior of the ejbPassivate method in a session bean, including the responsibilities of both the container and the bean provider. "
subsection - "Container's responsibility"
Material says - "The container may destroy a session bean instance if the instance does not meet the requirements for serialization after ejbPassivate."
Doubt --> Is it means, if the bean does not meet the requirements for passivation at the end of ejbPassivate() method, bean is destroyed? Is it true? I have read, if any of the member variables does not meet the requirements for passivation, container simply ignore those variables and the variables will be destroyed and the bean can't use the same varibales once the bean is activated by ejbActivate() method.

EJB spec 2.0, section 7.4.1:

The container may destroy a session bean instance if the instance does not meet the requirements for serialization after ejbPassivate.

3. Chapter 3 : Section - "Match the correct description about purpose and function to which session bean type they apply: stateless, stateful, or both."
Material Says:- "The conversational state of a STATEFUL session object is defined as the session bean instance�s field values, plus the transitive closure of the objects from the instance�s fields reached by following Java object references."
Doubt --> What is the meaning of, -- ' transitive closure of the objects from the instance�s fields reached by following Java object references. '
This means that all instance fields of all objects referenced from the session bean's instance fields (and recursively) are also part of the beans state. For instance, in the code below name and code are also part of the state of the stateful session bean along with anotherField.

public class SomeStatefulSessionBean implement SessionBean {
   private SomeClass someReference = new SomeClass();
   private String anotherField;
}
 
public class SomeClass {
   private String name;
   private AnotherClass ref = new AnotherClass();
}
 
public class AnotherClass {
   private String code;
}