An object-level gateway supporting integrated-property quality of service

As networks and the use of communications within applications continue to grow and find more uses, so too does the demand for more control and manageability of various "system properties" through middleware. An important component supporting an integrated property architecture is the concept of an object gateway, which is a quality-of-service (QoS)-aware element transparently inserted at the transport layer between clients and objects to provide managed communication behavior for the particular property being supported. In this paper, we introduce the concept of a QoS-oriented gateway to integrate a variety of QoS enforcement and implementation mechanisms controlling the underlying distributed interactions. We discuss the functions performed by such a component in achieving the desired overall end-to-end QoS, and the design considerations underlying our current implementation. We conclude with experiences to date with two variations of the gateway: one controlling managed latency and throughput using bandwidth allocation, and one controlling dependability through the coordination of object replicas.