System Support for distributed multimedia applications with guaranteed quality of service

We consider the problem of executing distributed multimedia applications with Quality of Service (QoS) requirements. Such applications involve several resources (CPU, network, file system, memory). In order to fulfill the QoS requirements of the applications, every resource manager must provide temporal guarantees, but this is not enough. An overall QoS management scheme must be set up for admission control and execution monitoring. Based on an analysis of application memory access time, we identify the key points where temporal guarantees must be provided. We present the tasks that must be achieved for overall QoS management and propose an implementation based on a QoS manager repli­ cated on each site and modified resource managers. Applications interact with one QoS manager only through a well-defined interface. As an illustration, we present the design of a File Server modified for providing guaranteed access time and its interactions with the QoS manager in the context of a distributed microkernel-based operating system.