To access DB2/OS390 from Oracle (on Solaris) there appear to be two options - Transparent Gateway and Generic Connectivity.
If you decide to use either of these products do you also need to go through DB2 Connect ?

Going the other way (accessing Oracle from DB2/OS390) what middleware is required ? Do you need for example IBM Data Joiner to achieve this ?

Any advice/experiences on doing this would be appreciated.