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While middleware platforms have been established in best-effort environments nowadays, support for QoS-sensitive services is still found lacking. More specifically, due to the high diversity of QoS requirements , the abstractions provided for QoS-unaware services cannot be maintained and the developer has to face the difficulties of low-level networking in(More)
This paper describes the design and implementation of a real-time, streaming, Internet video and audio player. The player has a number of advanced features including dynamic adaptation to changes in available bandwidth, latency and latency variation; a multi-dimensional media scaling capability driven by user-specified quality of service (QoS) requirements(More)
To simplify the task of building distributed streaming applications, we propose a new abstraction for information flow – Infopipes. Infopipes make information flow primary, not an auxiliary mechanism that is hidden away. Systems are built by connecting predefined component Infopipes such as sources, sinks, buffers, filters, broadcasting pipes, and(More)
Building applications that process information flows on existing middleware platforms is difficult, because of the variety of QoS requirements, the need for application-specific protocols, and the poor match of the commonly used abstraction of remote invocations to streaming. We propose Infopipes as a high-level abstraction for building blocks that handle(More)
Applications that process continuous information flows are challenging to write because the application programmer must deal with flow-specific concurrency and timing requirements, necessitating the explicit management of threads, synchronization, scheduling and timing. We believe that middleware can ease this burden, but middleware that supports(More)
The demand for QoS-support by mid-dleware platforms is continuously increasing, particularly in application domains such telecommunications or multimedia. Current object-oriented middleware, however, is not well suited to fulll this demand. In this paper, we propose a service-centred approach to QoS-supporting middleware, introducing the notion of smart(More)
Real-time systems seek to guarantee predictable run-time behaviour to ensure that tasks will meet their deadlines. Optimal scheduling decisions, however, easily impose unacceptable run-time costs for many but the most basic scheduling problems, specifically in the context of mul-tiprocessors and distributed systems. Deriving suitable heuristics then usually(More)