On 25 Oct 2005 22:29:07 -0700, "corejavagroups"
<sankar_battula@yahoo.co.in> wrote, quoted or indirectly quoted
someone who said :

Assuming you give an app direct access to all four database, over the
LAN,  it will have to open all four JDBC connections, each one with a
different JDBC driver manager.
http://mindprod.com/jgloss/jdbc.html

Another approach is to use a layer that sits atop JDBC and tries to
hide the details of which tables live in which databases. I don't know
if Hibernate for example can do that.  Obviously you can do joins
across tables not in the same database, at least not efficiently.
see http://mindprod.com/jgloss/hibernate.html

You might use a POD to intervene.
http://mindprod.com/jgloss/pod.html

EJBs might even have some table-driven  isolating abilities. I have
not explored them.  At least with EJB, clients of a given bean are
quite isolated from any of the SQL/JDBC.

http://mindprod.com/jgloss/ejb.html