Resolution: IBM's java porting guide says: "If your Java application is written 100% in the Java language, porting from 32-bit to 64-bit systems is very simple. Your 100% Java application will run unchanged - it will not even require to be recompiled." The only portion of the SmartSockets API that is not pure-Java is the PGM transoprt (the RTgms link driver). Those SmartSockets Java clients interfacing with RTgms would have to remain 32-bit, but all other SmartSockets Java clients can be ported to 64-bit.