XFA - locate specific nodes

Hi everybody,
I need some help on the following issue.
I have been able to add a xml data structure to xfa.datasets.data.
The xml data structure looks like this:
 

John
Doe

Jane
Doe

 
Now, at runtime, I would like to get a specific node using the id attribute (e.g., the user types the id on a textfield and javascript returns name and surname values of the relative node).
Coming from Acroform, I thought that LC had a method like XMLData.applyXPath() to locate nodes based on certain criteria, but as a matter of fact I wasn't able to find it.
Does that mean that I have to loop trough all the data structure nodes to find the one I am interested in? Or am I approaching the whole problem from a wrong perspective?
Thank you very much for your assistance.
 
Pierpaolo