JPA - tree structure mapping with toplink essential

Question

I'll try to explain it correctly.
I store a tree structure in a database. I have just two tables:
Node which contain a id , and some other info.
Tree which contain a parent and child
parent and child are ids from node.
Since each node can have several childs, and each node can have several parents, I had try a @ManyToMany relationship without sucess.
Here one small example of my tries :
@Entity
@Table(name="node")
public class Node {
@Id private int id;
private List<Node> childs;
private List<Node> parents;
@ManyToMany
@JoinTable(name="Tree")
public List<Node> getParents(){
     return parents;
@ManyToMany(mappedBy="parents")
public List<Node> getChilds(){
     return childs;
}But I always got several error.
Anyone have a working example that look like mine ?
Even after googling for several hours I still find nothing.
If it helps, I use toplink essential for my persistance layer.

Answer 1

Please see http://www.oracle.com/technetwork/middleware/toplink/index-085257.html for information on TopLink JPA support.
So as of TopLink 11, you will need to use EclipseLink's org.eclipse.persistence.jpa.PersistenceProvider as the provider class for JPA support, which is in the eclipselink.jar.
Best Regards,
Chris