The requirements for the QoS of distributed applications are traditionally expressed in terms of network oriented or systems oriented parameters. In general, the users of these services are not interested or capable of specifying the QoS of their services in such technical terms. In this paper, we propose modeling and engineering concepts for the mapping of end user QoS onto system and network QoS. We introduce QoS agents in structured object middleware that relate end-user QoS specifications to multimedia stream bindings. In fact, the middleware layer supports QoS classes, i.e., a set of QoS characteristics. The end user QoS requirements, generally a set of nonorthogonal specifications, must be supported using the available middleware QoS classes. We also describe the experimental environment that will be used to refine the QoS mapping mechanisms.
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