Quality of Service in Wide Area Distributed Systems

Quality of Service (QoS) has become an increasingly important concept in wide-area distributed systems. The overall QoS characteristics of a wide-area distributed system are influenced by the QoS of the individual hosts involved and the QoS of the communication subsystem connecting these hosts. In this paper, we include a general presentation of wide-area computing and Quality of Service concepts. QoS characteristics are presented at different system layers, such as software application, distributed platform, transport and network layers. We designed and implemented a framework for the creation, provisioning and management of QoS-enabled end-user services over IP networks. The framework takes high-level service requirements as an input and decomposes them into lowerlevel services at the various system layers involved. At the lowest system layers, devices are being configured and managed to provide the services specified at these