Q: Does XML-DBMS have a GUI interface?
Applies to: 1.x, 2.0
No. While people occasionally volunteer to write such an interface, nobody has yet done it. If you absolutely need such an interface, you should probably consider a commercial product such as HiT Allora or DB/XML Transform. For more information about these and other products, see XML Database Products: Middleware.
Note that version 2.0 was designed with a GUI interface in mind. So while writing the interface would not be trivial, it would at least be possible. It seems that the basic requirements would be:
A pane showing an XML schema on one side and a relational schema on the other, with the ability for users to join elements / attributes to tables / columns graphically. Since the code for doing the joins graphically is non-trivial to write, a simpler alternative is to let users select an element or attribute and then list the available tables / columns to which it can be mapped. The code behind this pane maintains the current mapping state as an XMLDBMSMap object.
A pane allowing users to generate a map and (optionally) a database schema from a DTD. The map could then be edited by the mapping pane. This pane would call MapFactory_DTD.
A pane allowing users to generate a map and (optionally) a DTD from a relational schema. The map could then be edited by the mapping pane. This pane would call MapFactory_Database.
A pane allowing users to editor a database schema. This would be most useful for modifying generated database schemas.
A pane allowing users to edit DTDs. This would be most useful for modifying generated DTDs. This could simply be a text pane.
A pane allowing users to transfer data according to a particular map, document, database, etc. This would call the Transfer tool.
It seems that Eclipse would be a good platform on which to build such a GUI.