Currently our setup is 9iR2 app server and 9iR2 database and we are utilizing OO4O on the app server.
My question is if we upgrade our app server to 10gR2 and database to 11g, what version of OO4O should I use? Do I use 10g version or 11g which I believe is packaged up as ODAC.
Thanks so much
OO4O follows the client certification, and client/database version interoperability can be found in the following note on My Oracle Support: Note 207303.1 Client / Server / Interoperability Support Between Different Oracle Versions
The "short answer" is that you can use a 10g client against an 11g database.
Hope it helps,