An approach to quality of service management in distributed multimedia application: Design and an implementation

Most work related to quality of service (QoS) is concerned with individual system components, such as the operating system or the network. However, to support distributed multimedia applications, the entire distributed system must participate in providing the guaranteed performance levels. In recogn ition of this, a number of QoS architectures have been proposed to provide QoS guarantees. The mechanisms and schemes proposed by those architectures are used in a rather static manner since the involved entities, e.g., the n etwork, sender and receiver, are known before the connection (call) set-up phase. In contrast to these architectures, we propose a general QoS managem ent framework which supports the dynamic choice of a configuration of syste m components to support the QoS requirements for the user of a specific app lication. We consider different possible system configurations and select t he most appropriate one depending on the desired QoS and the available reso urces. In this paper we present an overview of this general framework; espe cially, we concentrate on QoS negotiation and adaptation mechanisms. To sho w the feasibility of this approach, we designed and implemented a QoS manag er for distributed multimedia presentational applications, such as news-on- demand. The negotiation and adaptation mechanisms which are supported by th e QoS manager are specializations of the general framework. The proposed fr amework allows to improve the utilization of system resources, and thus to increase the system availability; it also allows to recover automatically, if this is possible, from QoS degradations. Furthermore, it provides the fl exibility to incorporate different resource reservation schemes and schedul ing policies, and to accommodate new system component technologies.