By Dr. Berg
BW 7.3 migrations always raises questions about the Java-ABAP stack. Here are some quick notes:
While ‘double stack’ upgrades are still possible, SAP NetWeaver Java 7.3 is now included with BW 7.3.
So the short story is that you should consider splitting the ABAP and Java stack as part of the 7.3 upgrade, if you have not already done so. Splitting the stack gives better scalability (multiple hardware servers). Also, the Java server is not used for IP after BW 7.30. It was re-developed in ABAP HTTP (Java no longer required), so plan for a switch during the upgrade.
Some useful tools/notes for moving forward...
A tool to split the stack is available in EhP2 (in SAPInst) and in SAPInst in ABAP 7.30.
When you finish the upgrade, you can also automatically create connections between Java-ABAP for EP/IP or front-end Java using CTC (see SAP notes: 983156, 1178800 for instructions).