The Java Remote Method Invocation (JRMI) specification simplifies the development of distributed Java applications, but provides little support to guarantee reliable, highly-available operation. The Aroma System is middleware that transparently enhances the JRMI model with the mechanisms required for consistent replication of client and server objects. By exploiting novel interception mechanisms, the Aroma System is activated at runtime, with minimal modification to the application and to the JRMI infrastructure. The Aroma System adapts the JRMI model for group communication, and exploits an underlying reliable, totally-ordered multicast protocol to provide strong replica consistency. We describe the architecture of the Aroma System, and discuss the mechanisms required to achieve transparent replication of Java RMI objects and to enforce strong replica consistency.