I had to change my datasource in a -ds.xml file. When I did that, the DataSource that my web-app was using became invalid and so I needed to restart my application. It would be cool if there was an option for DataSources returned by JNDI to point to the latest real DataSource at that location so that the DataSource returned to the client isn't invalid. Perhaps you might do this internally like so:
#1 used a wrapped DataSource for binding to JNDI.
#2 When updating a -ds.xml, lookup the existing DataSource in JNDI, get the delegate, shut it down and add the new "real" DataSource. (in an atomic fashion – naturally the DataSource needs to be synchronized).