persistence, derby and Database instance

[frederic barachant]

Hello.
I wish to use derby as my javax.persistence database (toplink, 
hibernate, ...). That should pose no problem, but i would like to be 
able to access the Database instance that is used to store my data, as i 
would need to backup it from time to time, ideally by getting a 
reference to it just the time to do that operation. Database would be local.
How can i get the Database, if i ensure that any info used to open the 
connection is known ( persistence unit XML parsing, ...) ?

Thank you.