Adaptive Quality-Aware Programming with Declarative QoS Constraints

O. Lampl and L. Böszörmenyi (Austria)


Quality of Service, Multimedia, Quality-aware Program ming, Declarative Constraints


Quality of service (QoS) has become one of the most important aspects of modern multimedia applications. Nevertheless, programming of QoS-aware, adaptive appli cations is cumbersome and error-prone. Several QoS oriented programming methods and tools have been presented, relying on special languages or complex frameworks. Instead, we suggest to slightly extend an existing general-purpose programming language and make thus adaptive programming as easy and as safe as any ”normal”, exception-based programming. We extend a general-purpose system programming language (C#) with the following features: (1) A time dimension, which can be added to any existing data type; (2) A new time-constrained assignment (streaming) statement and a time-constrained parameter passing (streaming) mode; (3) Declarative QoS specifications. We suggest some patterns for adaptive, quality aware programming and present sample implementations emphasizing the advantages of the new programming model. Performance measurements show negligible overhead when applying the new language features in real life multimedia applications.

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