Toplink XML: polymorphism/inheritance

Question

Hi all,
I have an XML like this (I have replaced the real business names by A, B, C, X ,etc etc)
[root]
[collectionOfX]
[A/]
[A/]
[B/]
[C/]
[C/]
[C/]
[collectionOfX]
[root]
On the Java side, A, B and C are concrete classes extending an abstract class X. I have one root class with a collection of Xs.
I am not able to map this stuff. Toplink requires to have concrete X elements with an attribute telling that it is in fact a A [X xsi:type="A"] and not [A]
I have seen that substitution groups were a possible way for doing this, how does it work?
If you have any indication about how to do this stuff, it is very welcome. I have not found any example of this.

Answer 1

Ok Blaise, the example you provided me is working and I was able to apply the same principle to my project which is now working also.
I want to share the "tricks" that will make it work for anyone after me who could face the same problem again.
1. A, B and C must be defined as elements and these elements must be used as both schema context and default root element in the descriptor info pane of the corresponding A, B and C classes. In my case, A, B and C were complexTypes in the schema and it was not working.
2. The abstract X class was added to the project but its descriptor was de-activated (maybe not really necessary)
3. I have Mapped the Inherited Attributes for A, B, C concrete classes. It means the X attributes are now appearing in the A, B and C list of attributes in the workbench.
4. The mapping of all inherited attributes is repeated in the workbench for all concrete classes (a pain if there are many attributes).
Blaise, if possible I would like to find a better support for this case in future versions of the product. Ideally, the mapping of inherited attributes should be defined only once.
Thx.
Robin