MOBA Java thread migration system. Implemented as a plug-in to Sun's Java Vitual Machine. Background Checkpointing Save, persist and restore a state of a running program. Process and Thread Migration Move a running program with its states to another machine. Via network. Traditionally, it is implemented as a function of a distributed OS. Application Dynamic load balancing. Improvement of fault tolerance. e.g. Move processes away from the machine which are going to be broken or shutted down. Disconnected operation. Recently, mobile agent.