[Exist-open] Unique resource IDs

[Leonard S. <sit...@uc...>]

Hi,

I've just started using eXist.  It's looking pretty nice.  Thanks for 
the wonderful open software!

I have a question about the unique IDs that are assigned to resources.

I stored a document in eXist.  I can get the resource from the 
collection using the filename that I used when I uploaded it through 
the admin page.

	String filename = collection.getResource("filename").getId()

When I do a query on the collection, for an element in the document, I 
can get an ID of the format of filename_#.  I suppose those numbers are 
the unique numbers that are described in
Wolfgang Meier. eXist: An Open Source Native XML Database.

I was hoping that I could directly access an element of the document 
using the unique ID, as in

	collection.getResource("filename_9")

That doesn't work.

Are the IDs assigned only when an XQuery is done?
Are the IDs unique within a collection?
Is there a way to retrieve the element directly via the ID?

The reason why I'm asking is that I want to store the ID somewhere 
else, and retrieve the element directly later on, or perhaps from a 
different application.  For example, I want to store information about 
the hierarchy of the organization I work in, as an XML document.  A web 
application will do stuff and get the ID from eXist, and store that in 
MySQL.  Later, if someone wants to search for all the stuff in MySQL 
associated with part of this organization, they lookup the ID from 
eXist, and then query MySQL for all the stuff.

Thanks for your help!

==Leonard E. Sitongia
     Web Engineering Group
     National Center for Atmospheric Research
     P.O. Box 3000 Boulder CO 80307  USA
     sit...@uc...    voice: (303)497-2454   fax: (303)497-1804