Flexible distributed systems for multimedia applications

This paper discusses how to make a distributed object system flexible so as to satisfy applications' requirements when changing the system environment. The system change is modeled to be the change of not only types of service but also quality of service (QoS) supported by the objects. There are two types of methods changing the objects, one for manipulating the states of the objects and another for changing QoS of the objects. We discuss new relations among methods with respect to QoS. By using the QoS-based relations, we newly discuss a QoS-based compensating way to recover the object from the less qualified state.