There are a few basic changes between RMI in JDK 1.1 and 1.2 that better support the Jini system, particularly object activation, and distributed garbage collection. The component that sends out a service request, known as the principal, communicates with other components needed to perform a service. The leasing system All services are granted as leases. Each service, when in use, is registered as being leased by another service. Leases can be exclusive or they can allow multiple requesting services to connect to a given service.
Leases are time-dependent and have to be renewed upon expiration.
The transaction system This transaction system is based on the common two-phased commit model. The system keeps records of the transaction environment before and after the transaction is processed so that it can be undone if necessary. The distributed event model is an extension of the system used in JavaBeans. An event is a notification system for the services to indicate that an action is to be taken. The distributed event mechanism requires that Jini services register with others to receive notification.