How is Inheritance handled by JDO.?(Seeking Clarification)

Question

Question about the following:
From the JDO Spec: 6.5
"For example, if an abstract class Component declares a key field masterId, the objectid class (which should be abstract as well) ComponentKey must also declare a field of the same type and name. Note that an instance of ComponentKey cannot be used to find a persistent instance, since it has no corresponding concrete persistent class.
A non-abstract class Part that extends Component must declare a non-abstract objectid class (for example, PartKey) that extends ComponentKey. There might be no key fields declared in Part or PartKey. Persistence-capable subclasses of Part must not have an objectid class.
Another non-abstract class Assembly that extends Component must declare a non-abstract objectid class (for example, AssemblyKey) that extends ComponentKey. If there is a key field, it must be declared in both Assembly and AssemblyKey. Persistence-capable subclasses of Assembly must not have an objectid class.
There might be other abstract classes or non-persistence-capable classes in the inheritance hierarchy between Component and Part, or between Component and Assembly. These classes are ignored for the purposes of objectid classes and key fields.
So the question is, If i have the following construct:
public abstract class DataModelObject {
  private Comparable id;
  public Comparable getId() { return this.id;}
  public void setId(Comparable id) { this.id = id; }
public abstract class MutableObject extends DataModelObject {
public class Customer extends MutableObject {
  private String name;
  public String getName() { return this.name; }
  public void setName(String name) { this.name = name; }
}Now, my goal is that when I make Customer a persistent object that the is field is an attribute of my persistent object and not a separate object in itself. The reason is that many objects in my data model have an iD and Id like to encapsulate it on the abstract level to facilitate its use. However, from what I read above, this is not the case? Could someone help clarfy this for me?
-- Regards,
-- Derisor

Answer 1

Hmmm ... maybe over everyone's head?