hello
As you said, JDO is using the system contracts of JCA to integrate within J2EE App Servers.
I'm not aware of any JDO implementation able to use the CCI part of JCA to access Legacy Data Sources.
This will be available in LiDO from xcalia in Q2 2005.
Even in that case you will still need a JCA connector on top of which LiDO will do the transparent mapping, exactly as ORM mapping tools are built on top of
JDBC (and you still need a JDBC driver).
Hope this helps.
Best Regards, Eric.