At one point Oracle offered a DRDA connector for AS400. You could set that up and then use DDM as you ask. I don't know if they still sell it.
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of Bruce Barrett
Sent: Wednesday, October 10, 2012 1:19 PM
Can we use DDM to connect to an Oracle database on a different server?