On a recent project we had a business and technology reason to connect Oracle EBS running 11g to a DB2 database.  After a few weeks of researching for the best practice and approach we decided on the following implementation steps.

1. Download a DB2 driver, such as from DataTek, and download to your application server in any storage directory.
2. Create a directory called “YM” under your custom application top.  example: $CUSTOM_TOP/java/YM.  (Assumes you have already created a $CUSTOM_TOP and it has a directory called “java”.
3. Copy all files from the storage directory to $CUSTOM_TOP/java/YM
4. Add 3 entries to s_adovar_classpath and s_adovar_afclasspath to point to the files in $CUSTOM_TOP/java/YM.
5. Make sure you run auto-config on your updated environment.
6. Bounce the application and database tier.
7. Perform any select, insert, update and or delete from the Oracle EBS application via java program to the DB2 database.  The java program will reference the DB2 connection from a jdbc connect string such as: “jdbc:oracle:db2://servername.com:port;databasename=xxxxxx; User=xxxx; Password=xxxx”